CN101175797B - Heat-shrinkable film, moldings and heat-shrinkable labels made by using the film, and containers made by using the moldings or fitted with the labels - Google Patents

Abstract

The object of the present invention is to obtain a heat-shrinkable film which is excellent in heat-shrinkable properties, mechanical properties such as impact resistance and transparency, and shrink processability, and which is suitable for applications such as shrink packaging, shrink-bundling packaging, and shrink labels. The film is made of a mixed resin containing polylactic acid resin (A) and (meth)acrylic resin (B), or polylactic acid resin (A) and polysiloxane acrylic composite rubber (D) as main components , or have at least one layer of the mixed resin layer, and the thermal shrinkage rate in the main shrinking direction of the film is 20% or more when immersed in warm water at 80°C for 10 seconds.

Description

Heat-shrinkable film, molded article using the heat-shrinkable film, heat-shrinkable label, and container using the molded article or affixing the label

technical field

The present invention relates to a heat-shrinkable film, a molded product using the heat-shrinkable film, a heat-shrinkable label, and a container on which the molded product or the label is attached. Heat-shrinkable films that are excellent in properties, transparency, etc., and are suitable for shrink packaging, shrink-bundling, or shrink labels, molded articles using the heat-shrinkable film, heat-shrinkable labels, and molded articles using the molded article or affixed with the heat-shrinkable film label container.

Background technique

Currently, soft drinks such as fruit juices and alcoholic beverages such as beer are sold in the state filled in containers such as bottles and PET bottles. At this time, in order to highlight the difference from other products or improve the visibility of the product, a printed heat-shrinkable label is often attached to the outside of the container. As a raw material for the heat-shrinkable label, polyvinyl chloride, polyester, polystyrene, and the like are generally used.

英等有害气体的原因，因此，从近年来环境保护的观点来看，正在开发使用代替PVC类材料的热收缩性薄膜。Polyvinyl chloride-based (hereinafter referred to as "PVC-based") heat-shrinkable films have good shrink processability and natural shrinkability (that is, small natural shrinkage), and have been widely used as heat-shrinkable labels in the past. However, when incinerated after use, hydrogen chloride, di

Therefore, from the viewpoint of environmental protection in recent years, heat-shrinkable films that replace PVC-based materials are being developed and used.

In addition, as a polystyrene-based heat-shrinkable film mainly made of styrene-butadiene block copolymer (SBS), it has better shrinkage processability than PVC-based and polyester-based heat-shrinkable films. Such advantages, but they also have problems such as low stiffness and poor natural shrinkage.

For the above use, a polyester-based heat-shrinkable film that is rigid at room temperature, has low-temperature shrinkability, and has good natural shrinkability is mainly used. However, compared with PVC-based heat-shrinkable films, polyester-based heat-shrinkable films have the problem that uneven shrinkage and wrinkles are likely to occur during heat-shrinkage.

And, if the above-mentioned plastic film is discarded in the natural environment, it will not be decomposed due to its chemical stability, and it will be accumulated as garbage, causing a problem of environmental pollution. In addition, since the above-mentioned plastic film is produced from fossil resources such as petroleum, there is also a problem of depletion of future fossil resources.

From the viewpoint of reducing the above problems, plant-derived biodegradable plastics such as polylactic acid resins are known as materials that contribute to saving fossil resources.

Since the polylactic acid-based resin is a plant-derived plastic made of lactic acid obtained from starch such as corn or potato, and has excellent transparency, it is particularly attracting attention for applications such as films.

However, due to the brittleness of the raw material of the polylactic acid resin itself, when it is directly molded into a sheet or film, sufficient strength cannot be obtained, and it is difficult to put it into practical use. In particular, uniaxially stretched uniaxially shrinkable films have not been stretched to improve the brittleness in the unstretched direction, and thus sufficient mechanical properties such as impact resistance cannot be obtained. In addition, there is a problem that crystallization proceeds during heating, and sufficient heat shrinkage properties cannot be obtained.

As various methods for improving mechanical properties such as impact resistance of the polylactic acid-based resin, a method of including a resin composition in the polylactic acid-based resin has been proposed. For example, a method of containing polymethacrylic acid in a polylactic acid-based resin having a specific weight-average molecular weight has been disclosed (see Patent Document 1), and a method of containing an aliphatic polyester other than polylactic acid in a polylactic acid-based resin has been disclosed. method (see Patent Document 2), method of containing polycaprolactone in polylactic acid resin (refer to Patent Document 3), method of containing polyolefin such as ethylene-vinyl acetate copolymer in polylactic acid resin (refer to Patent Document 4), method of containing aliphatic aromatic polyester in polylactic acid-based resin with adjusted copolymerization ratio of L-lactic acid and D-lactic acid (see Patent Document 5), containing ethylene-vinyl acetate in polylactic acid-based resin Polyolefins such as ester copolymers (see Patent Document 6), and methods of adjusting the crystallinity of polylactic acid resins and improving shrinkage processing characteristics by further blending aliphatic polyester resins (see Patent Document 7).

However, the main purpose of the polylactic acid-based resin described in Patent Document 1 is to improve its heat resistance and transparency, and there is a problem that it is difficult to apply it to improve shrinkability as a heat-shrinkable film. In addition, the polylactic acid-based resins described in Patent Documents 2 to 4 are intended to improve their brittleness while maintaining their transparency, and it is difficult to apply them to improving shrinkability as a heat-shrinkable film.

In addition, the polylactic acid-based resins described in the above-mentioned Patent Documents 5 and 7 can suppress crystallization when heated as a heat-shrinkable film, but there is a problem of uneven shrinkage, wrinkles, and dents due to rapid shrinkage. Furthermore, the polylactic acid-based resin described in the above-mentioned Patent Document 6 still has a problem that sufficient shrinkage processability cannot be obtained as compared with a polyvinyl chloride-based heat-shrinkable film as a heat-shrinkable film.

In addition, as a method of improving the brittleness of polylactic acid resins, a method of using a composition composed of polylactic acid and a modified olefin compound has been disclosed (refer to Patent Document 8), using a polymer mainly composed of lactic acid, a fat The method of plasticized polylactic acid composition formed by aliphatic polyester plasticizer mainly composed of aliphatic carboxylic acid and chain molecular diol (refer to Patent Document 9), using polylactic acid and epoxidized diene embedded A method using a biodegradable resin composition formed of a segment copolymer (see Patent Document 10), a method using a lactic acid-based polymer composition composed of polylactic acid, aliphatic polyester, and polycaprolactone (Patent Document 11), A method using a polylactic acid-based resin composition comprising crystalline polylactic acid and at least one rubber component selected from natural rubber and polyisoprene (Patent Document 12).

However, when the above-mentioned polycaprolactone, modified olefin compound, epoxidized diene-based block copolymer, natural rubber, polyisoprene, etc. are mixed with lactic acid-based resin, although the impact resistance is exhibited It improves the effect, but as a result, the transparency is significantly impaired, so it is difficult to call it a perfect technology when it is used in applications such as packaging materials that require confirmation of the contents.

In addition, it is also known to mix polyacetal resin and diene rubber, natural rubber, silicone rubber, polyurethane rubber with polylactic acid resin, or to contain methyl (meth)acrylate in the shell layer, and to contain methyl (meth)acrylate in the core layer. A method of improving impact resistance by an impact modifier such as a multilayer structure selected from at least one of styrene units and butadiene units (see Patent Document 13), but it is not sufficient as a heat-shrinkable film .

In addition, a method of blending a graft copolymer obtained by graft-polymerizing a rubbery polymer and a vinyl monomer into a polylactic acid-based resin has also been proposed (see Patent Document 14), but this is not sufficient as a heat-shrinkable film. .

Patent Document 1: JP-A-2005-036054

Patent Document 2: Japanese Unexamined Patent Publication No. 9-169896

Patent Document 3: Japanese Unexamined Patent Publication No. 8-300481

Patent Document 4: Japanese Unexamined Patent Publication No. 9-151310

Patent Document 5: JP-A-2003-119367

Patent Document 6: JP-A-2001-011214

Patent Document 7: JP-A-2000-280342

Patent Document 8: Japanese Unexamined Patent Application Publication No. 09-316310

Patent Document 9: JP-A-2000-191895

Patent Document 10: JP-A-2000-219803

Patent Document 11: JP-A-2001-031853

Patent Document 12: JP-A-2003-183488

Patent Document 13: JP-A-2003-286400

Patent Document 14: JP-A-2004-285258

Contents of the invention

The problem to be solved by the invention

The present invention was made in view of the above-mentioned problems, and the object of the present invention is to obtain mechanical properties such as heat-shrinkable properties, impact resistance, and transparency, as well as excellent shrink processability, and to be suitable for applications such as shrink packaging, shrink-bundling packaging, and shrink labels. Heat shrinkable film.

Another object of the present invention is to obtain molded articles, heat-shrinkable labels, and containers with the above-mentioned heat-shrinkable film suitable for shrink packaging, shrink-bundling, or shrink-labeling.

Solution to the problem

The heat-shrinkable film according to the present invention is characterized in that the film is made of a mixed resin containing polylactic acid resin (A), or has at least one layer of the mixed resin, and when immersed in warm water at 80°C for 10 seconds The thermal shrinkage rate in the main shrinking direction of the film is more than 20%.

In addition, the mixed resin may contain (meth)acrylic resin (B) and a rubber-like component (C) in addition to the polylactic acid resin (A), and the polylactic acid resin (A) may be added to the mixed resin. ) to the (meth)acrylic resin (B), and the mass ratio to the rubbery component (C) are within the prescribed ranges.

In addition, as a mixed resin, in addition to polylactic acid resin (A), polysiloxane acrylic composite rubber (D) may be contained as a main component, and the polylactic acid resin (A) and polysiloxane acrylic composite rubber may be compounded. The mass ratio of rubber (D) is within a predetermined range.

Furthermore, the heat-shrinkable film according to the present invention can also be made into a sheet having at least two layers of (I) layer composed of mixed resin and (II) layer mainly composed of polylactic acid resin (A), Among them, the mixed resin contains a rubber-like component (C) in addition to the polylactic acid-based resin (A).

Invention effect

According to the present invention, it is possible to provide a heat-shrinkable film that is excellent in heat-shrinkable properties and suitable for applications such as shrink packaging, shrink-bundling packaging, and shrink labels.

According to the present invention, it is also possible to provide a molded article using the above-mentioned heat-shrinkable film suitable for applications such as shrink wrapping, shrink-bundling, or shrink-wrapping, a heat-shrinkable label, and a container using the above-mentioned molded article or affixed with a heat-shrinkable label. .

In addition, when the (meth)acrylic resin (B) or the rubber-like component (C) is used, it is possible to obtain a heat-shrinkable material having excellent mechanical properties such as heat-shrinkability, transparency, and impact resistance, and also excellent shrinkage processability. film.

In addition, when a mixed resin containing silicone acrylic composite rubber (D) is used at a predetermined ratio, it is excellent in thermal shrinkage characteristics, mechanical properties such as impact resistance and transparency, and shrinkage processability.

Furthermore, when a film having a predetermined heat shrinkage rate is used as the (I) layer, heat shrinkage characteristics, mechanical properties such as impact resistance and transparency, and shrinkage processability are excellent, and the film having a predetermined heat shrinkage rate is used. A hybrid resin containing three components: polylactic acid resin (A), (meth)acrylic resin (B), and rubber-like component (C).

Detailed ways

The present invention relates to a heat-shrinkable film, which is characterized in that the film is made of a mixed resin containing polylactic acid resin (A), or has at least one layer of the mixed resin, and is immersed in 80°C warm water for 10 seconds The thermal shrinkage rate in the main shrinkage direction of the film is more than 20%.

Among the heat-shrinkable films, the first and second heat-shrinkable films contain polylactic acid resin (A) and (meth)acrylic resin (B) (also contains rubber-like component (C)) as a mixed resin , and the mass ratio of polylactic acid resin (A) and (meth)acrylic resin (B) (and rubber-like component (C)) in the mixed resin is within a prescribed range.

In addition, the third heat-shrinkable film among the heat-shrinkable films contains a polylactic acid-based resin (A) and a polysiloxane-acrylic composite rubber (D) as a mixed resin, and the polylactic acid-based resin (A) and The mass ratio of the polysiloxane-acrylic composite rubber (D) is within the specified range.

Furthermore, the fourth heat-shrinkable film in the heat-shrinkable film is made by making the heat-shrinkable film according to the present invention have (I) layer composed of mixed resin and polylactic acid resin (A) as the main component. The at least two-layer sheet of the (II) layer contains, as a mixed resin, a (meth)acrylic resin (B) and a rubbery component (C) in addition to the polylactic acid resin (A).

Hereinafter, the 1st heat-shrinkable film - the 4th heat-shrinkable film are demonstrated respectively. First, various resins constituting these heat-shrinkable films will be described.

In addition, in this specification, the term "containing as a main component" means that the function of the resin constituting each layer of various heat-shrinkable films (one layer of a single layer body or each layer of a laminated body) is not damaged, Other ingredients are allowed within the scope of the effect. In addition, this term is not limited to a specific content rate, but is a component accounting for 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more of all constituent components of each layer.

[Various resins constituting the first heat-shrinkable film to the fourth heat-shrinkable film]

<Polylactic acid resin (A)>

In the present invention, the so-called polylactic acid resin refers to a homopolymer of D-lactic acid or L-lactic acid or a copolymer thereof, specifically, poly(D-lactic acid) whose structural unit is D-lactic acid, structural unit Poly(L-lactic acid), which is L-lactic acid, and (DL-lactic acid), which is a copolymer of L-lactic acid and D-lactic acid, also includes mixtures thereof.

In addition, when the polylactic acid-based resin (A) used in the present invention is a mixture of D-lactic acid and L-lactic acid, the mixing ratio of D-lactic acid and L-lactic acid (hereinafter referred to as "D/L ratio") is D - the value of lactic acid/L-lactic acid, which may be 99.8/0.2 or less or 0.2/99.8 or more, preferably 99.5/0.5 or less or 0.5/99.5 or more, more preferably 99/1 or less or 1/99 or more, and still more preferably 97/3 or less or 3/97 or more, more preferably 95/5 or less or 5/95 or more, most preferably 92/8 or less or 8/92 or more.

In addition, the D/L ratio may be 75/25 or more or 25/75 or less, preferably 85/15 or more or 15/85 or less, more preferably 80/20 or more or 20/80 or less, still more preferably 90/10 or more or below 10/90.

When the D/L ratio is higher than the above upper limit, for example, when D/L=100/0 (that is, D-lactic acid) or 0/100 (that is, L-lactic acid), it shows very high crystallinity and a high melting point , there is a tendency to be excellent in heat resistance and mechanical properties. However, when used as a heat-shrinkable film, since printing and a bag-making process using a solvent are involved, it is generally necessary to appropriately reduce the crystallinity of the constituent materials themselves in order to improve printing suitability and solvent-tightness. Also, when the crystallinity is too high, orientation crystallization proceeds during stretching, and film shrinkage properties tend to decrease during heating. In addition, even in a film whose crystallization is suppressed by adjusting the stretching conditions, crystallization occurs before shrinkage due to heating during thermal shrinkage, and as a result, uneven shrinkage or insufficient shrinkage tends to occur. Therefore, the D/L of the polylactic acid-based resin used in the present invention is preferably within the above range.

On the other hand, when the D/L ratio is lower than the above-mentioned lower limit value, since there is almost no crystallinity, it is easy to cause troubles such as melting and sticking due to heat when the labels touch each other after heat shrinkage, and a large decrease in fracture resistance. .

That is, if the D/L ratio is not more than the above upper limit, it is easier to obtain a heat shrinkable film with good shrinkage properties such as heat shrinkability and shrinkage processability. In addition, if the D/L ratio is not less than the above lower limit , it is easier to suppress shrinkage unevenness, and a heat-shrinkable film with excellent shrinkage characteristics can be obtained.

In the present invention, in order to adjust the D/L ratio of the polylactic acid resin (A) more easily, polylactic acid resins having different copolymerization ratios of D-lactic acid and L-lactic acid may be blended. In this case, it is sufficient that the average value of the copolymerization ratios of D-lactic acid and L-lactic acid of the plurality of lactic acid-based polymers is within the above-mentioned range. Depending on the purpose of use, a balance between heat resistance and heat shrinkage properties can be obtained by blending two or more polylactic acid-based resins having different copolymerization ratios of D-lactic acid and L-lactic acid and adjusting the crystallinity.

In addition, the polylactic acid-based resin (A) used in the present invention may be a copolymer of the above-mentioned L-lactic acid or D-lactic acid, α-hydroxycarboxylic acid other than lactic acid, diol, and dicarboxylic acid, or a copolymer of L- Copolymers of lactic acid or D-lactic acid, α-hydroxycarboxylic acids other than lactic acid or diols, and dicarboxylic acids as main components.

Here, examples of the "α-hydroxycarboxylic acid" to be copolymerized include optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), glycolic acid, 3-hydroxy Butyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methylbutyric acid, 2- Bifunctional aliphatic hydroxycarboxylic acids such as hydroxycaprolactic acid (2-hidroxicaprolactone acid) and 2-hydroxycaproic acid, or lactones such as caprolactone, butyrolactone, and valerolactone.

In addition, examples of the "diol" to be copolymerized include aliphatic diols such as ethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. Moreover, examples of the "dicarboxylic acid" to be copolymerized include aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid.

The copolymerization ratio of lactic acid and the copolymerization target monomer selected from α-hydroxycarboxylic acid, aliphatic diol and aliphatic dicarboxylic acid in the copolymer is not particularly limited, but due to the higher proportion of lactic acid, the consumption of petroleum resources Less is therefore preferred.

Specifically, the copolymerization ratio of the above-mentioned lactic acid as a lactic acid-based copolymer and the above-mentioned copolymerization target monomer is lactic acid: copolymerization target monomer = 95:5 to 10:90, preferably 90:10 to 10:90, more preferably 80:20 to 20:80, more preferably 30:70 to 70:30. When the copolymerization ratio is within the above range, a film having a good balance of physical properties such as rigidity, transparency, and impact resistance can be obtained.

In addition, the above-mentioned lactic acid homopolymer and the above-mentioned lactic acid-based copolymer may be used alone or in combination.

The polylactic acid-based resin (A) used in the present invention can be produced by known polymerization methods such as polycondensation and ring-opening polymerization. For example, in the polycondensation method, the polylactic acid-based resin (A) having an arbitrary composition can be obtained by directly dehydrating and polycondensing D-lactic acid, L-lactic acid, or a mixture thereof.

In addition, in the ring-opening polymerization method (lactide method), it is possible to obtain a compound having an arbitrary composition by ring-opening polymerization of lactide, which is a cyclic dimer of lactic acid, in the presence of a predetermined catalyst using a polymerization regulator or the like as necessary. Polylactic acid-based resin (A). Among the above-mentioned lactides, there is DL-lactide which is a dimer of L-lactic acid, and these can be mixed and polymerized as necessary to obtain a polylactic acid-based resin (A) having an arbitrary composition and crystallinity.

Examples of the lactide include L-lactide which is a dimer of L-lactic acid, D-lactide which is a dimer of D-lactic acid, and DL-lactide which is a dimer of D-lactic acid and L-lactic acid. These can be mixed and polymerized as necessary to obtain a lactic acid homopolymer having an arbitrary composition or crystallinity.

The polylactic acid resin (A) used in the present invention has a weight (mass) average molecular weight of 20,000 or more, preferably 40,000 or more, more preferably 50,000 or more, still more preferably 60,000 or more, particularly preferably 100,000 or more, and the upper limit is 400,000 or less, preferably 350,000 or less, more preferably 300,000 or less, still more preferably 250,000 or less. When the weight (mass) average molecular weight is more than the above-mentioned lower limit, moderate resin cohesion can be obtained, insufficient tensile strength or embrittlement of the film can be suppressed, and disadvantages such as a decrease in mechanical strength can be prevented. On the other hand, when a weight (mass) average molecular weight is below the said upper limit, melt viscosity can be reduced, and it is preferable from a viewpoint of manufacture and productivity improvement.

In addition, the above-mentioned polylactic acid-based resin (A) may contain a small amount of other copolymerization components for the purpose of improving heat resistance and the like. As this other copolymerization component, aromatic diols, such as aromatic carboxylic acid, such as terephthalic acid, and the ethylene oxide adduct of bisphenol A, etc. are mentioned, for example. In addition, in order to increase the molecular weight, it may also contain a small amount of chain extenders, such as diisocyanate compounds, epoxy compounds, acid anhydrides, acid chlorides, and the like.

If the polylactic acid-based resin (A) has a predetermined Vicat softening point, the heat-shrinkable film obtained will have good shrinkage characteristics, which is preferable. The lower limit temperature of the Vicat softening point is preferably 50°C or higher, more preferably 55°C or higher, and the upper limit temperature is preferably 95°C or lower, more preferably 85°C or lower.

If the lower limit temperature of the Vicat softening point is 50° C. or higher, spontaneous shrinkage can be suppressed even if the obtained heat-shrinkable void-containing film is left at a temperature slightly higher than normal temperature, for example, in summer. On the other hand, if the upper limit temperature is 95° C. or lower, the film can be stretched at a low temperature, and good shrinkage properties can be imparted to the stretched film.

Examples of commercially available polylactic acid-based resins include "Nature Works" (manufactured by Cargilldow), "LACEA" (manufactured by Mitsui Chemicals Co., Ltd.), and the like.

<(Meth)acrylic resin (B)>

Next, the (meth)acrylic resin (B) will be described. Since the (meth)acrylic resin (B) is compatible with the polylactic acid resin (A), it is possible to adjust the glass transition temperature that affects shrinkage characteristics by blending with the polylactic acid resin (A), Therefore, it is a resin effective in improving shrinkage processability. In addition, in this specification, "(meth)acryl" means "acryl or methacryl".

The (meth)acrylic resin (B) used in the present invention is a homopolymer of methyl methacrylate or a copolymer of methyl (meth)acrylate and other vinyl monomers. Examples of the vinyl monomer include ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, (Meth)acrylates such as 2-ethylhexyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate; unsaturated acids such as (meth)acrylic acid; styrene, α-methylbenzene Ethylene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, etc.

In addition, the copolymer may contain elastomer components such as polybutadiene or butadiene/butyl (meth)acrylate copolymers, polybutylene (meth)acrylate copolymers, glutaric anhydride units, Glutarimide unit. Among them, polymethyl methacrylate (PMMA), which is a homopolymer of methyl methacrylate, and polymethyl methacrylate (PMMA), which is selected from the group consisting of methyl (meth)acrylate and (meth)acrylic acid, are preferably used from the viewpoint of rigidity and moldability. A copolymer formed of two or more monomers in ethyl ester, butyl (meth)acrylate, and (meth)acrylic acid. In particular, if polymethyl methacrylate (PMMA) is blended, the glass transition temperature of the (meth)acrylic resin (B) can be increased, and as a result, the rapid initial shrinkage during shrinkage can be eased, and a good Shrinkage processability is therefore particularly preferred.

The weight (mass) average molecular weight of the (meth)acrylic resin (B) used in the present invention is desirably 20,000 or more, preferably 40,000 or more, more preferably 60,000 or more, and 400,000 or less, preferably 350,000 or less, more preferably Below 300,000.

If the weight (mass) average molecular weight of the (meth)acrylic resin (B) is 20000 or more, it can suppress that film tensile strength is insufficient or embrittlement. On the other hand, if the weight (mass) average molecular weight of the (meth)acrylic resin (B) is 400,000 or less, the melt viscosity can be lowered, which is preferable from the viewpoint of production and productivity improvement.

Examples of commercially available (meth)acrylic resins (B) include "Sumipex" (manufactured by Sumitomo Chemical Co., Ltd.), "Acrypet" (manufactured by Mitsubishi Rayon Co., Ltd. ), "Parapet (パラペット)" (manufactured by Kuraray), "Alteuglass" (manufactured by Atofina Japan), "Delpet (delpet)" (manufactured by Asahi Kasei Chemical Co., Ltd.), and the like.

<Rubber-like component (C)>

The rubber-like component (C) used in the present invention refers to depolymerization for improving the impact resistance of a film obtained from a mixed resin of the above-mentioned polylactic acid resin (A) and (meth)acrylic resin (B). The rubber component other than the lactic acid resin (A) preferably contains the rubber-like component within a range that does not impair the heat shrinkability and rigidity of the film.

As the aforementioned rubber-like component (C), specifically, lactic acid-based copolymers other than the aforementioned polylactic acid-based resin (A), aliphatic polyesters, aromatic aliphatic polyesters, aromatic polyesters, diols, and dicarboxylic acids Copolymers of acid and the above-mentioned lactic acid homopolymer, core-shell rubber, ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer (EAA, etc.), ethylene-ethyl acrylate copolymer ( EEA), and ethylene-(meth)methyl acrylate copolymer (EMA), etc. Among them, it is preferable to use a core-shell structure type rubber.

Examples of the aforementioned aliphatic polyesters include polyhydroxycarboxylic acids, aliphatic polyesters obtained by condensation of aliphatic diols and aliphatic dicarboxylic acids, aliphatic polyesters obtained by ring-opening polymerization of cyclic lactones, and synthetic polyesters. Aliphatic polyester, etc.

Examples of the aforementioned polyhydroxycarboxylic acid include 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyn-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methyl Homopolymers or copolymers of hydroxycarboxylic acids such as butyric acid, 2-methyllactic acid, and 2-hydroxycaprolactic acid.

As the aliphatic polyester obtained by condensation of the above-mentioned aliphatic diol and aliphatic dicarboxylic acid, one or more kinds of aliphatic diol and aliphatic dicarboxylic acid described below are respectively selected and condensed, or according to It is necessary to add an isocyanate compound or the like to increase the molecular weight to obtain a desired high molecular weight polymer.

The aliphatic polyester obtained by condensation of the above-mentioned aliphatic diol and aliphatic dicarboxylic acid can be obtained by using a mixture of ethylene glycol, propylene glycol, 1,4-butanediol, hexanediol, One or more aliphatic diols such as diol, cyclopentanediol, cyclohexanediol, and 1,4-cyclohexanedimethanol, or their anhydrates or derivatives, and selected from succinic acid, One or more aliphatic dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, and dodecanedioic acid, or their anhydrides or derivatives are polycondensed. At this time, if necessary, an isocyanate compound or the like may be added to perform chain extension to obtain a desired polymer. As the above-mentioned aliphatic polyester, for example, "Bionolle (ビオノ一レ)" (manufactured by Showa Polymer Co., Ltd.), trade name "Plamate (プラメメト)" (Dainippon Ink Chemicals Co., Ltd. )) or trade name "GS-PLA" (manufactured by Mitsubishi Chemical Corporation), etc.

Examples of the aliphatic polyester obtained by ring-opening polymerization of cyclic lactones include one or more selected from ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone, and the like. Cyclic monomers, and polymerized substances. In addition, examples of the aforementioned synthetic aliphatic polyester include copolymers of cyclic acid anhydrides such as succinic anhydride and epoxides such as ethylene oxide or propylene oxide, and the like. Specifically, it is commercially available under the trade name "Celgreen" (manufactured by Daicel Chemical Industry Co., Ltd.), or "Ton Polymer" (manufactured by Union Carbide Japan Co., Ltd.).

Next, as the aromatic aliphatic polyester, one in which an aromatic ring is introduced between aliphatic chains to lower crystallinity can be used. Examples of aromatic aliphatic polyesters include, for example, condensation of aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and aliphatic diols; aliphatic diols or derivatives thereof; or aromatic diols or their derivatives; Substances obtained by condensation of derivatives and aliphatic dicarboxylic acids or derivatives thereof, etc.

Examples of the aromatic dicarboxylic acid include isophthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, and terephthalic acid, among which terephthalic acid is most preferably used.

In addition, examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like, and adipic acid is most preferably used.

In addition, examples of the aliphatic diol include the above-mentioned diols. Moreover, the ethylene oxide adduct of bisphenol A etc. are mentioned as an aromatic diol.

In addition, two or more kinds of aromatic dicarboxylic acids, aliphatic dicarboxylic acids, or aliphatic diols may be used, respectively.

Representative examples of the aforementioned aromatic aliphatic polyesters include copolymers of 1,4-butylene adipate and terephthalate, polybutylene adipate and terephthalic acid ester copolymers, etc. As 1,4-butylene adipate and terephthalate copolymer, EasterBio (manufactured by Eastman Chemicals) is commercially available as polybutylene adipate and terephthalate As an ester copolymer, Ecoflex (manufactured by BASF Corporation) is commercially available.

Examples of the structure of the above-mentioned diol, dicarboxylic acid, and polylactic acid-based resin copolymer include random copolymers, block copolymers, and graft copolymers, and any structure may be used. However, from the viewpoint of impact resistance and transparency of the film, block copolymers and graft copolymers are preferable. Specific examples of random copolymers include "GS-Pla" (manufactured by Mitsubishi Chemical Corporation, trade name), and specific examples of block copolymers or graft copolymers include "Plamate" (Dainippon Co., Ltd. Ink Chemical Industry Co., Ltd., trade name).

The method for producing the copolymer of polylactic acid resin, diol and dicarboxylic acid is not particularly limited, for example, ring-opening of polyester or polyether polyol having a dehydration condensation structure of diol and dicarboxylic acid, and lactide can be mentioned. Polymerization, or a method obtained by transesterification. In addition, methods obtained by subjecting polyester or polyether polyol having a structure formed by dehydration condensation of diol and dicarboxylic acid to polylactic acid-based resin by dehydration/dediol condensation or transesterification are also mentioned.

The weight-average molecular weights of lactic acid-based copolymers, aliphatic polyesters, aromatic aliphatic polyesters, and aromatic polyesters other than the polylactic acid-based resin (A) used as the above-mentioned rubber-like component (C) are desirably below The limit is 50,000 or more, preferably 100,000 or more, and the upper limit is preferably 400,000 or less, preferably 300,000, more preferably 250,000 or less. When the lower limit thereof is 50,000 or more, troubles such as deterioration of mechanical strength are less likely to occur. On the other hand, if the upper limit is 400,000 or less, the melt viscosity can be lowered, which is preferable from the viewpoint of production and productivity improvement.

In addition, the aforementioned core-shell structure type rubber refers to a rubber-like component having a multilayer structure of two or more layers of a core portion and a shell portion. This core-shell structure rubber has a high impact resistance improvement effect, and is finely dispersed in (A) component by compounding with (A) component, so it hardly impairs the transparency of lactic acid resin, and can greatly improve the impact resistance. Shocking.

Examples of the aforementioned core-shell structure rubber include diene-based core-shell structure polymers such as methacrylic acid-butadiene copolymers and acrylonitrile-butadiene-styrene copolymers; methacrylic acid-styrene-propylene Acrylic core-shell polymers such as nitrile copolymers. Among them, a polysiloxane-methacrylic acid-methyl methacrylate copolymer having good compatibility with polylactic acid-based resins and forming a film with a balanced impact resistance and transparency is more preferably used. Specifically, "Metablen C, E, W" (manufactured by Mitsubishi Rayon Co., Ltd.), "カネエ一ス" (manufactured by Kaneka Corporation) and the like are commercially available.

As the above-mentioned ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer (EAA), ethylene-(meth)acrylate copolymer (EMA), ethylene-(meth)acrylate copolymer The copolymer (EMMA) preferably uses comonomers other than ethylene and has a content of 10% by mass or more, preferably 20% by mass or more, more preferably 40% by mass or more, and is 90% by mass or less, preferably 80% by mass or less , more preferably 70% by mass or less, particularly preferably 60% by mass or less. When the comonomer content other than ethylene is 10% by mass or more, the effect of improving the crack resistance of the film can be sufficiently obtained, and transparency can be maintained. When it is 90 mass % or less, the rigidity of the whole film can be maintained, and heat resistance is favorable. Among these, ethylene-vinyl acetate copolymer (EVA) is more preferably used.

As the above-mentioned ethylene-vinyl acetate copolymer (EVA), "EVAFLEX" (manufactured by Mitsui DuPont Polymer Chemicals Co., Ltd., trade name), "Novatec (ノバテック) EVA" ( Mitsubishi Chemical Co., Ltd., trade name), "Ebaslen" (Dainippon Ink Chemicals Co., Ltd., trade name), "Evatate (エバテテト)" (Sumitomo Chemical Co., Ltd., trade name), " "Soablen" (manufactured by Nippon Synthetic Chemicals Co., Ltd., brand name) and the like.

As the above-mentioned ethylene-acrylic acid copolymer (EAA), "Novatec EAA" (manufactured by Mitsubishi Chemical Corporation, trade name) and the like are commercially available. In addition, as the ethylene-(meth)acrylic acid copolymer (EMA), "Noafloi AC" (manufactured by Mitsui DuPont Polymer Chemicals Co., Ltd., trade name) and the like are commercially available. In addition, "Acryft" (manufactured by Sumitomo Chemical Co., Ltd., trade name) and the like are commercially available as the ethylene-methyl (meth)acrylate copolymer (EMMA).

<Silicone acrylic compound rubber (D)>

Next, the above-mentioned silicone acrylic composite rubber (D) will be described.

The polysiloxane-acrylic composite rubber (D) is added to improve the impact resistance of the polylactic acid resin (A). This polysiloxane-acrylic composite rubber (D) not only has excellent low-temperature properties, but also has a high effect of improving impact resistance, and is finely dispersed in the polylactic acid-based resin (A) by compositing with acrylic acid, so it can hardly damage lactic acid. Resin-like transparency greatly improves impact resistance.

The polysiloxane acrylic composite rubber (D) has a core-shell structure. Specific examples thereof include those in which the core portion is formed from a copolymer of a silicone compound and a (meth)acrylic monomer, and the shell portion is formed from a homopolymer or copolymer of a (meth)acrylic monomer.

Dimethicone etc. are mentioned as said siloxane compound. Moreover, as a (meth)acrylic-type monomer used for a core part, butyl (meth)acrylate, 2-ethylhexyl acrylate, etc. are mentioned. Moreover, methyl (meth)acrylate etc. are mentioned as a (meth)acrylic-type monomer used for a shell part.

When using the polysiloxane acrylic composite rubber having the above-mentioned core-shell structure, since the polymer formed from the (meth)acrylic monomer is contained in the shell portion, the difference between the (meth)acrylic monomer and the (meth)acrylic monomer in the core portion is High affinity, and high affinity with the polylactic acid resin placed outside the polysiloxane acrylic composite rubber. Therefore, in the above-mentioned polysiloxane-acrylic composite rubber, the core-shell structure can stably exist, and the dispersion state can be stably maintained in the above-mentioned mixed resin.

As a specific example of the silicone-acrylic composite rubber, Metablen S-2001 manufactured by Mitsubishi Rayon Co., Ltd. can be mentioned.

<Glass transition temperature (Tg)>

The mixed resin containing the polylactic acid-based resin (A) used in the present invention can shift the glass transition temperature (Tg) to a high-temperature region compared to the case where the polylactic acid-based resin is used alone. Specifically, the mixed resin containing the polylactic acid resin (A) used in the present invention has a Tg of 40°C or higher, preferably 45°C or higher, more preferably 50°C or higher, and 100°C or lower, preferably 90°C below, more preferably below 85°C. If Tg is 40° C. or higher, natural shrinkage can be suppressed, and if Tg is 100° C. or lower, stretching at low temperature is possible and sufficient shrinkage characteristics are obtained. As a method of adjusting Tg within the above range, there is, for example, a method of mixing a predetermined amount of (meth)acrylic resin (B) in addition to the method of using the polylactic acid resin (A) specified in the present invention. The Tg of the mixed resin can be measured using, for example, a differential scanning calorimeter (DSC).

<Other added ingredients>

In the present invention, within the scope of not significantly impairing the effect of the present invention, it may also contain polyethylene resin, polypropylene resin, polystyrene resin (general polystyrene (GPPS), rubber modified impact resistance Polystyrene (HIPS), polystyrene-polybutadiene-polystyrene block copolymer (SBS), polystyrene-polyisoprene-polystyrene block copolymer (SIS), polystyrene Ethylene-poly(ethylene/butylene) block-polystyrene copolymer (SEBS), polystyrene-poly(ethylene/propylene) block-polystyrene copolymer (SEPS), polystyrene-poly(ethylene - Ethylene/propylene) block-polystyrene copolymer (SEEPS), styrene-carboxylic acid copolymer, etc.), polyamide resin, polyoxymethylene resin and other thermoplastic resins (hereinafter referred to as "other thermoplastic resins") At least one of the above.

In addition, in the present invention, in order to improve various properties of the impact resistance, transparency, moldability, and heat-shrinkable film, a plasticizer may be added as necessary within the range that does not impair the effects of the present invention. Examples of the plasticizer include fatty acid ester plasticizers, phthalate-based plasticizers, and trimellitate-based plasticizers.

As specific examples of the above-mentioned fatty acid ester plasticizers, dibutyl adipate, diisobutyl adipate, diisononyl adipate, diisodecyl adipate, di( 2-ethylhexyl), di-n-octyl adipate, di-n-decyl adipate, dibutyldiethylene glycol adipate, dibutyl sebacate, bis(2- ethylhexyl), di-n-hexyl azelate, bis(2-ethylhexyl azelate), bis(2-ethylhexyl dodecanedioate), etc.

Specific examples of the phthalate-based plasticizer include diisononyl phthalate, diisodecyl phthalate, bis(2-ethylhexyl) phthalate, and the like. In addition, examples of the trimellitate-based plasticizer include tris(2-ethylhexyl) trimellitate.

In addition to the aforementioned thermoplastic resins and plasticizers, additives (hereinafter referred to as as "other various additives"). For example, recycled resin or inorganic particles such as silica, talc, kaolin, and calcium carbonate, pigments such as titanium oxide and carbon black, flame retardants, weather-resistant stabilizers, heat-resistant Stabilizer, antistatic agent, melt viscosity modifier, crosslinking agent, lubricant, nucleating agent, antiaging agent, etc.

[Various Heat Shrinkable Films]

Next, the first to fourth heat-shrinkable films will be described respectively.

In addition, the so-called "film main shrinkage direction" in the present invention means the direction in which the thermal shrinkage rate is large in the longitudinal direction (longitudinal direction) and the transverse direction (width direction). , the so-called "film vertical direction" means the direction perpendicular to the main shrinkage direction.

<Heat shrinkage rate>

The heat shrinkage ratios of the first to fourth heat-shrinkable films are indicators for judging the suitability of the shrinking process in a relatively short period of time (several seconds to tens of seconds) for applications such as shrink labels for PET bottles. At present, in the application of labeling PET bottles, as the most widely used shrinking processing machine in the industry, water vapor is used as the heating medium for shrinking processing, and the shrinking processing machine is generally called a steam shrinking machine. In addition, the heat-shrinkable film needs to be sufficiently heat-shrinkable at as low a temperature as possible from the viewpoint of the influence of heat on the object to be wrapped. However, in the case of a film with high temperature dependence and extreme shrinkage ratios depending on temperature, there are likely to be parts whose shrinkage behavior is different due to temperature unevenness in the steam shrinking machine, so there may be shrinkage unevenness, Wrinkles, dents, etc., and a tendency to deteriorate the appearance of shrinkage processing.

From these viewpoints including industrial productivity, if the thermal shrinkage rate in the main shrinkage direction of the film is 20% or more when immersed in warm water at 80°C for 10 seconds, the coating object can be fully bonded within the shrinkage processing time. Adhesion, and no spots, wrinkles, or depressions, can get a good shrinkage appearance, so it is preferred.

In addition, when the film of the present invention is used as a heat-shrinkable label, when immersed in warm water at 80°C for 10 seconds, the heat shrinkage rate in the direction perpendicular to the main shrinking direction of the film is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. If immersed in warm water at 80°C for 10 seconds, the heat shrinkage rate in the direction perpendicular to the main shrinkage direction of the film is 10% or less, then the dimension perpendicular to the main shrinkage direction of the film itself will not become shorter after heat shrinkage, and the shrinkage printing Designs and characters are less likely to be deformed, and in the case of a rectangular bottle, problems such as longitudinal tension are less likely to occur, which is preferable.

<The first heat-shrinkable film>

The first heat-shrinkable film of the present invention (hereinafter also referred to as "first film") is made of a mixed resin layer of polylactic acid resin (A) and (meth)acrylic resin (B), or has At least one film of the mixed resin layer is stretched in a uniaxial direction.

(mixing ratio of polylactic acid resin (A) and (meth)acrylic resin (B))

For the mixed resin that becomes the main component of the mixed resin layer constituting the first film, it is important to make the mass ratio of the above-mentioned polylactic acid resin (A) and (meth)acrylic resin (B) such that (A)/(B ) = within the range of 95/5 to 50/50. When the content of the (meth)acrylic resin (B) is 5% by mass or more based on the total mass (100% by mass) of the mixed resin, the film shrinkage characteristics, shrinkage processability, and transparency can be sufficiently improved. On the other hand, if the content of the (meth)acrylic resin (B) is 50% by mass or less, the impact resistance of the film will not be significantly reduced, and the stretchability at low temperatures can be maintained. (70° C. to 90° C. or so) is preferable because a sufficient heat shrinkage rate is obtained. The mixed resin used in the first film is more preferably such that the mass ratio of the polylactic acid resin (A) to the (meth)acrylic resin (B) is (A)/(B)=90/10 to 60/ 40 range.

(Amount of rubber component (C) added)

In addition, the first film may incorporate the rubber component (C) described above. The rubber component (C) is desirably added in an amount of 3% by mass or more, preferably 9% by mass or more, more preferably It is 13 mass % or more, more preferably 16 mass % or more, and is 45 mass % or less, Preferably it is 43 mass % or less, More preferably, it is 41 mass % or less. If the added amount of the rubber component (C) is in the range of 13% by mass to 45% by mass, the rigidity and transparency of the film will not be impaired, and it can be suitably used as a heat-shrinkable label.

(other ingredients)

In addition, the above-mentioned other additive components may be added to the first film as needed.

(layer structure)

The structure of the first film may be a single layer, or may be a laminated structure in order to impart surface functional properties such as lubricity, heat resistance, solvent resistance, and easy adhesion to the film surface. For example, when layer (I) mainly composed of polylactic acid resin (A) and (meth)acrylic resin (B) is laminated with layers (II) and (III) having different resin compositions or additives , can enumerate (I)/(II), (II)/(I)/(II), (II)/(I)/(III), (II)/(I)/(III)/(II) Equal layer structure example. In addition, the lamination ratio of each layer can be adjusted as appropriate according to the use and purpose.

(thickness)

The total thickness of the first film is not particularly limited, but it is preferably thin from the viewpoints of transparency, shrinkability, raw material cost, and the like. Specifically, the total thickness of the film after stretching is 80 μm or less, preferably 70 μm or less, more preferably 50 μm or less, still more preferably 40 μm or less. In addition, the lower limit of the total thickness of the film is not particularly limited, but it is preferably 20 μm or more in consideration of the handleability of the film.

(ΔHm and ΔHc)

In the first film, when the temperature is raised from -40°C to 250°C at a heating rate of 10°C/min using a differential scanning calorimeter (DSC), the amount of heat ΔHm and temperature rise necessary to melt all the crystals contained in the film It is very important to measure the heat difference ΔHc generated by crystallization (ΔHm-ΔHc) to be 25 J/g or less, and it is desirable to adjust it to preferably 20 J/g or less, more preferably 15 J/g or less, and most preferably It is in the range of 10 J/g or less.

Here, ΔHm is the amount of heat that melts all the crystals contained in the film when the temperature is raised from -40°C to 250°C at a heating rate of 10°C/min using a differential scanning calorimeter (DSC), and represents the degree of crystallization of the film scale, but this also includes the influence of crystallization that occurs during temperature rise measurements. Therefore, the original degree of crystallization of the thin film can be obtained by subtracting the heat of crystallization ΔHc derived from the crystallization during temperature rise measurement. If the above-mentioned (ΔHm-ΔHc) is 25 J/g or less, in addition to sufficiently suppressing crystallization due to heat shrinkage, and easily adjusting to the above-mentioned heat shrinkage range, it is difficult to cause a decrease in the mechanical strength of the film over time, Therefore, it is practically preferable. In addition, when the first thin film has a laminated structure, it is sufficient as long as (ΔHm-ΔHc) of the entire film layer is within the above-mentioned range, and from the viewpoint of heat resistance and solvent resistance of the surface layer, it is preferable to adjust and improve the crystallinity to a certain extent. sex.

(heat shrinkage)

As mentioned above, it is important that the thermal shrinkage rate of the first film in the main shrinking direction of the film is 20% or more when immersed in 80°C warm water for 10 seconds, more preferably 25% or more, still more preferably 30% or more. And, the upper limit thereof is preferably 65%.

In addition, when the first film is immersed in warm water at 60° C. for 10 seconds, the heat shrinkage rate in the main shrinkage direction of the film is preferably 25% or less. In addition, the difference between the thermal shrinkage rate in the main shrinkage direction of the film when immersed in warm water at 60°C for 10 seconds and the thermal shrinkage rate in the main shrinkage direction of the film when immersed in warm water at 80°C for 10 seconds is desired to be 20% to 70%. , preferably 20% to 60%, more preferably 20% to 50%.

In the first film, it is important to adjust the mixing ratio of the mixed resin constituting the film and/or (ΔHm-ΔHc) within the range specified in the first film so that the heat shrinkage rate of the film falls within the above range , In addition, it can be adjusted by controlling the stretch ratio to be 2 times to 10 times, the stretching temperature to be 60°C to 110°C, and the heat treatment temperature to be in the range of 60°C to 100°C.

(tensile modulus of elasticity)

In the stiffness (rigidity at normal temperature) of the first film, the tensile elastic modulus in the direction perpendicular to the main shrinkage direction of the film is preferably 1200 MPa or more, more preferably 1400 MPa or more, even more preferably 1600 MPa or more. In addition, the upper limit value of the tensile modulus of the heat-shrinkable film generally used is about 3000 MPa, Preferably it is about 2900 MPa, More preferably, it is about 2800 MPa. If the tensile elastic modulus in the direction perpendicular to the main shrinkage direction of the film is 1200 MPa or more, the stiffness of the film as a whole (rigidity at room temperature) can be increased. When the bag-made film is covered on a container such as a PET bottle, it is less likely to cause problems such as easy lid tilting or a decrease in yield due to film folding, etc., so it is preferable. In addition, the main shrinkage direction of the film referred to in this specification means the direction in which the stretching direction is larger in the longitudinal direction and the transverse direction, for example, when it is attached to a bottle, it is the direction corresponding to the outer peripheral direction.

(transparency)

Regarding the transparency of the first film, the haze value of the film is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less when measuring a film having a thickness of, for example, 50 μm according to JIS K7105. When the haze value is 10% or less, the transparency of the film can be obtained and the display effect can be exerted.

(impact resistance)

The impact resistance of the first film is evaluated by the tensile elongation at break. In a tensile test at 0°C, especially in label applications, the elongation in the film drawing (flow) direction (MD) It is 100% or more, preferably 150% or more, more preferably 200% or more. If the tensile elongation at break in the 0°C environment is 100% or more, it is less likely to cause defects such as film breakage in processes such as printing and bag making, which is preferable. In addition, when the tension applied to the film is increased as the speed of the process such as printing and bag making increases, it is preferable that the tensile elongation at break is 100% or more because it is difficult to break.

(Manufacturing method)

The first thin film can be produced by a known method. The form of the film may be either flat or tubular, but it is preferably flat from the standpoint of productivity (chitin can be taken as a product in the width direction of the roll film) or printing on the inner surface. shape. As a method for producing a planar film, for example, resins are melted using multiple extruders, co-extruded from a T-die, cooled and solidified with cold rolls, rolled and stretched in the longitudinal direction, and stretched in the transverse direction. A method of stretching with a tenter, annealing, cooling, (corona discharge treatment is applied to the surface when printing), and winding with a coiler to obtain a film. In addition, a method of cutting a film produced by a tubular method into a planar shape can also be used.

In applications that shrink in two directions such as lamination, the stretch ratio is 2 to 10 times in the longitudinal direction, 2 to 10 times in the transverse direction, preferably 3 to 6 times in the longitudinal direction, and 3 to 10 times in the transverse direction. About 6 times. On the other hand, in applications such as heat-shrinkable labels that mainly shrink in one direction, it is desirable to select a magnification ratio that is substantially in the uniaxial stretching range as follows, that is, the direction corresponding to the main shrinking direction 2 to 10 times, preferably 4 to 8 times, and 1 to 2 times in the direction perpendicular to the main shrinkage direction (1 time means the case of no stretching), preferably 1.1 to 1.5 times. A biaxially stretched film stretched at a stretch ratio within the above range does not cause excessive heat shrinkage in the direction perpendicular to the main shrinkage direction. When , even in the height direction of the container, heat shrinkage of the film, which is the so-called longitudinal tension phenomenon, can be suppressed, so it is preferable.

The stretching temperature needs to be changed according to the glass transition temperature of the resin used or the properties required for the heat-shrinkable film, but it is generally controlled at 60°C or higher, preferably 70°C or higher, and the upper limit is 100°C or lower, preferably The range below 90°C. In addition, depending on the characteristics of the resin used, the stretching method, the stretching temperature, the shape of the target product, etc., it is 1.5 to 10 times in the main shrinkage direction, preferably 3 to 7 times, and more preferably 3 to 5 times. Within the range of magnification, the stretching magnification is appropriately determined in the uniaxial or biaxial direction. In addition, when uniaxially stretching in the transverse direction, it is effective to provide a weak stretch of about 1.05 times to 1.8 times in the longitudinal direction in order to improve the mechanical properties of the film and the like. Next, if necessary, in order to reduce the natural shrinkage rate or improve heat shrinkage characteristics, etc., after heat treatment or relaxation treatment at a temperature of about 50°C to 100°C, the stretched film is cooled rapidly before the molecular orientation is relaxed. , forming a heat-shrinkable film.

In addition, surface treatment or surface processing such as corona treatment, printing, coating, and vapor deposition may be performed on the first film as necessary, and bag-making processing or perforation processing may be performed using various solvents or heat sealing.

The first film is processed from a planar shape into a cylindrical shape according to the object to be packaged, and is provided for packaging. When printing is required on cylindrical containers such as PET bottles, the required image can be printed on one side of a wide flat film rolled on a roll, and then cut to the required width and folded at the same time And make the printing surface on the inside, and then seal the center (the shape of the sealed part is a so-called envelope) to form a cylindrical shape. As the center sealing method, an adhesive method using an organic solvent, a method using heat sealing, a method using an adhesive, and a method using an impulse sealer are considered. Among these, an adhesion method using an organic solvent is suitably used from the viewpoint of productivity and appearance.

<Second Heat Shrinkable Film>

The second heat-shrinkable film of the present invention (hereinafter also referred to as "second film") is made of a mixed resin layer of polylactic acid resin (A) and (meth)acrylic resin (B), or has at least A film formed by stretching a film of the mixed resin layer in a uniaxial direction.

(mixing ratio of polylactic acid resin (A) and (meth)acrylic resin (B))

For the mixed resin in the second film, the quality of the above-mentioned polylactic acid resin (A) and (meth)acrylic resin (B) is preferably (A)/(B)=91/9 or less, and preferably 83/17 or less, more preferably 77/23 or less, more preferably 33/67 or more, preferably 64/36 or less, more preferably 62/38. When the content of the (meth)acrylic resin (B) is more than the above range, the effect of improving the shrinkage characteristics, shrinkage processability, and transparency of the film can be obtained. On the other hand, if the content is less than the above range, the impact resistance of the film will not be significantly reduced, and the stretchability and shrinkage characteristics at low temperatures can be maintained, and the practical temperature range (70°C to 90°C or so can be sufficiently obtained. ) thermal shrinkage rate.

(Amount of rubber component (C) added)

The above-mentioned rubber component (C) may be added to the second film. The rubber component (C) is desirably added in an amount of 3% by mass or more, preferably 9% by mass or more, more preferably It is 13% by mass or more, more preferably 16% by mass or more, desirably 45% by mass or less, preferably 43% by mass or less, more preferably 41% by mass or less. If the added amount of the rubber component (C) is in the range of 13% by mass to 45% by mass, the rigidity and transparency of the film will not be impaired, and it can be suitably used as a heat-shrinkable label.

(other added ingredients)

In addition, in the second film, the above-mentioned other additive components may be added as needed.

(layer structure)

The structure of the second thin film may be a single layer, or may be a laminated structure in order to impart new functions such as lubricity, heat resistance, solvent resistance, and easy adhesion to the surface. For example, in polylactic acid resin (A) and (meth)acrylic resin (B), or polylactic acid resin (A) and (meth)acrylic resin (B) and rubber component (C) When layer (II) and layer (III) with different resin compositions or additives are laminated on the layer (I), two-layer structures of (I)/(II), (II)/(I)/ (II), a three-layer structure of (II)/(I)/(III), or a four-layer structure of (II)/(I)/(III)/(II), etc. are taken as examples. In addition, the ratio of the lamination thickness of each layer can be set arbitrarily according to the use and purpose.

(thickness)

The total thickness of the second film is not particularly limited, but it is preferably thin from the viewpoints of transparency, shrinkage processability, raw material cost, and the like. Specifically, the upper limit of the total film thickness after stretching is 80 μm or less, preferably 70 μm or less, more preferably 50 μm or less. In addition, the lower limit of the total thickness of the heat-shrinkable film is not particularly limited, but it is preferably 20 μm or more in consideration of the handleability of the film.

(Manufacturing method)

The second thin film can be produced by a known method. The shape of the heat-shrinkable film may be any of planar shape and tubular shape. A planar film can be made of chitin in its width direction, and printing can also be performed on the inner surface, so it is preferable. For example, the production method of a planar film is to melt the resin using multiple extruders, co-extrude it from a T-die, and cool and solidify it using a chill roll. Then, roll stretching in the longitudinal direction, tenter stretching in the transverse direction, cooling after annealing treatment, (when printing is carried out, the printed surface is subjected to corona discharge treatment), and coiled with a coiler. . In addition, a method of cutting a film produced by a tubular method into a planar shape can also be used.

In applications that shrink in two directions such as lamination, the stretch ratio is 2 to 10 times in the longitudinal direction, 2 to 10 times in the transverse direction, preferably 3 to 6 times in the longitudinal direction, and 3 to 10 times in the transverse direction. About 6 times. A biaxially stretched film stretched at a stretch ratio within these ranges does not cause excessive heat shrinkage in the direction perpendicular to the main shrinkage direction. , even in the height direction of the container, the thermal shrinkage of the film, which is the so-called longitudinal tension phenomenon, can be suppressed. On the other hand, in applications such as heat-shrinkable labels that mainly shrink in one direction, it is desirable to select a magnification ratio that is substantially in the uniaxial stretching range as follows, that is, the direction corresponding to the main shrinking direction 2 to 10 times, preferably 4 to 8 times, and 1 to 2 times in the direction perpendicular to the main shrinkage direction (1 time refers to the case of no stretching), preferably 1.01 to 1.5 times.

In addition, the stretching temperature needs to be adjusted according to the glass transition temperature of the resin contained or the properties required for the heat-shrinkable film, but it can be controlled at a lower limit of 60°C or higher, preferably 70°C or higher, and an upper limit of 100°C. °C or lower, preferably in the range of 90 °C or lower. On the other hand, it is 1.5 to 10 times in the main shrinkage direction, preferably 3 to 7 times, more preferably 3 The stretching ratio is appropriately determined in the uniaxial or biaxial direction in the range of 5 times to 5 times. In addition, when uniaxially stretching in the transverse direction, it is effective to stretch in the longitudinal direction to about 1.05 to 1.8 times in order to improve the mechanical properties of the film and the like.

In addition, if necessary, in order to reduce the natural shrinkage rate or improve heat shrinkage characteristics, etc., after heat treatment or relaxation treatment at a temperature of about 50°C to 100°C, the stretched film is rapidly cooled before the molecular orientation is relaxed. , thereby forming a heat-shrinkable film. In addition, surface treatment or surface processing such as corona treatment, printing, coating, and vapor deposition can be performed as needed, and bag-making processing or perforation processing can be performed using various solvents or heat sealing.

The second film is processed from a planar shape into a cylindrical shape according to the object to be packaged, and is supplied for packaging. For example, when printing is required on a cylindrical container such as a PET bottle, the required image is first printed on one side of a wide flat film wound on a roll, and then cut into a predetermined width and folded for use. A method in which the printing surface is on the inside, and the center is sealed (the shape of the sealed part is called an envelope) to form a cylindrical shape. As the center sealing method, an adhesion method using an organic solvent, heat sealing, an adhesive, or a pulse sealer is considered. Among them, an adhesion method using an organic solvent can be used from the viewpoint of productivity and appearance.

(heat shrinkage)

As mentioned above, when the second film is immersed in warm water at 80°C for 10 seconds, the lower limit value of the thermal shrinkage rate in the main shrinkage direction of the film may be 20% or more, preferably 30% or more, and the upper limit value is 70% or less. , preferably 65% or less. In general, heat-shrinkable films need to be sufficiently heat-shrinkable at as low a temperature as possible from the viewpoint of the influence of heat on the object to be wrapped. Therefore, if it is a film with a thermal shrinkage rate of 20% to 70% under the above conditions, it can be fully adhered to the object to be coated within the shrinkage processing time, and spots, wrinkles, dents, etc. will not occur, and A good shrink processed appearance can be obtained.

In the second film, in order to adjust the thermal shrinkage rate in the main shrinkage direction when immersed in 80° C. warm water for 10 seconds to the above range, it is preferable to adjust the resin composition as described in the present invention, and at the same time adjust the stretching temperature to The range described below. For example, when it is necessary to further increase the thermal shrinkage rate, increase the optical isomer ratio of the polylactic acid resin (A), increase the content of the (meth)acrylic resin (B), increase the stretch ratio, and reduce the stretch ratio. temperature etc.

In addition, when the second film is used as a heat-shrinkable label, when immersed in warm water at 80°C for 10 seconds, the heat shrinkage rate in the direction perpendicular to the main shrinkage direction is preferably 10% or less, more preferably 5% or less, even more preferably 3% or less. If it is a heat-shrinkable film with a thermal shrinkage rate of 10% or less in the direction perpendicular to the main shrinking direction, the dimension itself in the direction perpendicular to the main shrinking direction of the film after shrinking can be suppressed from becoming shorter, and printed patterns or characters after shrinking can be suppressed. In addition, even in the case of a rectangular bottle, it is possible to suppress failures such as longitudinal tension.

(storage modulus)

In the present invention, the storage modulus (E'), that is, when measured using a viscoelastic spectrometer at a vibration frequency of 10 Hz and a deformation of 0.1%, is measured at 70° C. in a direction perpendicular to the main shrinkage direction. It is very important to adjust the lower storage modulus (E') to 100MPa ~ 1.5GPa. If the storage modulus (E') at 70°C is 100 MPa or more, since the strength in the shrinkage temperature range can be maintained, even under a wide range of shrinkage conditions, the shrinkage processability is good and a good appearance can be obtained , and is also preferable from the viewpoint of including industrial productivity. In addition, the upper limit of the storage elastic modulus (E') is not particularly specified, but if it is 1.5 GPa or less, the low-temperature shrinkability is not impaired, so it is preferable, more preferably 1.2 GPa or less, and even more preferably 1.0 GPa or less. .

In the second film, in order to increase the storage modulus (E') at 70°C, it is preferable to adjust the resin composition or the production method as described in the present invention. Specific adjustment methods include reducing the optical isomer ratio of the polylactic acid resin (A), increasing the content of the (meth)acrylic resin (B), reducing the amount of plasticizer added, increasing the stretching temperature, Increase the heat treatment temperature and other methods. In addition, in order to reduce the storage modulus (E') at 70°C, examples include increasing the optical isomer ratio of the polylactic acid resin (A), reducing the content of the (meth)acrylic resin (B), increasing The amount of plasticizer added, reducing the stretching temperature, reducing the heat treatment temperature and other methods.

(tensile modulus of elasticity)

The lower limit of the tensile modulus of the second film in the direction perpendicular to the main shrinkage direction of the film is preferably 1.2 GPa or more, more preferably 1.4 GPa or more, and still more preferably 1.6 GPa or more. The upper limit of the tensile elastic modulus of a heat-shrinkable film generally used is about 3.0 GPa, preferably about 2.9 GPa, and more preferably about 2.8 GPa. When the said tensile modulus of elasticity is 1.2 GPa or more, the stiffness (rigidity at normal temperature) of the whole film can be improved. Therefore, especially when the thickness of the film is thinned, when the bagged film is covered on a container such as a PET bottle with a labeling machine, it is possible to suppress the occurrence of easily tilted lids or the reduction in yield due to film folding. and other bad situations. The above-mentioned tensile modulus of elasticity can be measured under the condition of 23° C. in accordance with JIS K7127.

In the second film, it is preferable to adjust the resin composition or the production method as described in the present invention so that the tensile modulus of elasticity falls within the above-mentioned range. In order to increase the tensile elastic modulus, specific adjustment methods include, for example, methods such as increasing the content of the (meth)acrylic resin (B) and decreasing the content of the rubbery component (C).

(transparency)

Regarding the transparency of the second film, when measured according to JIS K7105, for example, a film with a thickness of 50 μm, the haze value is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less. This is because if the haze value is 10% or less, the transparency of the film can be obtained and a display effect can be exhibited.

In the second film, it is preferable to adjust the resin composition or the production method as described in the present invention so that the haze value falls within the above-mentioned range. As a specific adjustment method, it can be mentioned that reducing the content of (meth)acrylic resin (B) and rubbery component (C) relative to polylactic acid resin (A); The compatibility of various raw materials, or increasing the mixing efficiency to reduce the dispersed particle size; reducing the stretching ratio; slightly increasing the stretching temperature and other methods.

(tensile elongation at break)

The impact resistance of the second film is evaluated by the tensile elongation at break. In the tensile test at 23°C, especially in the application of heat-shrinkable labels, in the film drawing (flow) direction (MD, that is, The elongation in the direction perpendicular to the main shrinkage direction) is 100% or more, preferably 150% or more, more preferably 200% or more. If the tensile elongation at break in an environment of 23° C. is 100% or more, defects such as film breakage are less likely to occur in processes such as printing and bag making. In addition, when the tension applied to the film increases as the speed of the process such as printing and bag making increases, it is preferable that the tensile elongation at break is 150% or more because it is difficult to break. In addition, the upper limit of the preferred tensile elongation at break is not particularly limited, but it is preferably about 500% in order to produce a film at a sufficient speed.

In order for the second film to have an elongation in a tensile test at 23° C. within the above range, it is preferable to configure the resin composition or the production method as described in the present invention. As its specific adjustment method, for example, reducing the content of the (meth)acrylic resin (B) constituting the film, increasing the content of the rubber-like component (C), and performing a step of 1.01 times or more in the direction of pulling (flow) methods such as stretching. The tensile elongation at break of the second film can be measured at a tensile speed of 200 mm/min based on JIS K7127.

<The third heat-shrinkable film>

The third heat-shrinkable film of the present invention (hereinafter also referred to as "the third film") is made of a mixed resin layer containing polylactic acid resin (A) and polysiloxane acrylic composite rubber (D) as main components film.

(Compounding amount of polysiloxane acrylic compound rubber (D))

In the third film, the compounding amount of the polysiloxane-acrylic composite rubber (D) is the mass ratio of the polylactic acid-based resin (A) to the polysiloxane-acrylic composite rubber (D) (polylactic acid-based resin (A) /polysiloxane acrylic composite rubber (D)), it is preferably 95/5 to 50/50, more preferably 90/10 to 60/40, even more preferably 85/15 to 70/30. By blending the polysiloxane-acrylic compound rubber in this range, the transparency of the polylactic acid resin can be hardly impaired, and the impact resistance can be improved.

(Amount of (meth)acrylic resin (B) added)

In addition, the above-mentioned (meth)acrylic resin (B) may be added to the third film. The content of the (meth)acrylic resin (B) is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more and 30% by mass or less, preferably It is 25 mass % or less, More preferably, it is 20 mass % or less. If the content of the (meth)acrylic resin is 5% by mass or more, the glass transition temperature can be shifted to the high temperature side, and the shrinkage initiation temperature can be brought close to the shrinkage temperature region, so a gentle shrinkage curve can be obtained, and as a result Shrinkage processability can be improved. On the other hand, when the said content is 30 mass % or less, since the remarkable fall of a film impact resistance can be suppressed, it is preferable.

((C) component)

Moreover, in the said mixed resin of a 3rd film, (C)component can also be contained in the range which does not significantly impair the effect of this invention.

(addition of flexible resin)

In addition, in the mixed resin of the third film, in order to improve the impact resistance, transparency, moldability and various properties of the heat-shrinkable film, within the range that does not significantly impair the effect of the present invention, polysiloxane may be added. Flexible resin other than oxyalkane-acrylic composite rubber.

Examples of the aforementioned flexible resin include aliphatic polyester resins other than polylactic acid resins, aromatic aliphatic polyester resins, copolymers of diols, dicarboxylic acids and lactic acid resins, core-shell rubbers, And ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-(meth)acrylic acid copolymer (EMA), ethylene-(methyl) ) methyl acrylate copolymer (EMMA), etc.

Among the above flexible resins, aliphatic polyester resins other than polylactic acid resins are particularly preferable. The aliphatic polyester resin other than polylactic acid resin is an aliphatic polyester mainly composed of aliphatic dicarboxylic acid or its derivatives and aliphatic polyhydric alcohol. Examples of the aliphatic dicarboxylic acid residue constituting the aliphatic polyester resin include residues derived from succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, and the like. Furthermore, examples of the aliphatic polyhydric alcohol residue include aliphatic diol residues derived from ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and the like.

The aliphatic dicarboxylic acid residues preferably used in the third film are succinic acid residues or adipic acid residues, and the aliphatic polyhydric alcohol residues are 1,4-butanediol residues.

In addition, the aliphatic dicarboxylic acid preferably used for the third film preferably has a melting point of 100°C to 170°C. By adjusting the melting point to this range, the aliphatic polyester can maintain a crystalline state even in the range of 60°C to 100°C where shrinkage usually takes place, and therefore, it functions as a pillar during shrinkage, whereby a more stable polyester can be obtained. Good shrinkage processability.

The content of the aliphatic polyester-based resin other than the above polylactic acid-based resin is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and 30% by mass or less, preferably 25% by mass or less , more preferably 20% by mass or less. If the content of the above-mentioned aliphatic polyester-based resin other than the above-mentioned polylactic acid-based resin is 5% by mass or more, the effect of suppressing shrinkage in the stretching direction and the perpendicular direction can be exhibited, and shrinkage processability can be improved. In addition, if When it is 30 mass % or less, the fall of transparency can be suppressed.

(Manufacturing method)

The third film can be produced by a known method using the above mixed resin. The form of the film may be either flat or tubular, but it is preferably flat from the standpoint of productivity (chitin can be taken as a product in the width direction of the roll film) or printing on the inner surface. shape.

As a method for producing a planar film, for example, resins are melted using multiple extruders, co-extruded from a T-die, cooled and solidified with a cold roll, rolled and stretched in the longitudinal direction, and stretched in the transverse direction. Stretching with a tenter, annealing, cooling, and printing, corona discharge treatment is performed on the surface, and then coiled with a coiler to obtain a film. In addition, a method of cutting a film produced by a tubular method into a planar shape is also mentioned.

In the application of shrinkage in two directions such as lamination, the stretching ratio in the above-mentioned stretching is 2 times to 10 times in the longitudinal direction, 2 times to 10 times in the transverse direction, preferably 3 times to 6 times in the longitudinal direction, Horizontal is about 3 times to 6 times. On the other hand, in applications such as heat-shrinkable labels that mainly shrink in one direction, it is desirable to select a magnification ratio that is substantially in the uniaxial stretching range as follows, that is, the direction corresponding to the main shrinking direction 2 times to 10 times, preferably 3 times to 7 times, more preferably 3 times to 5 times, and the direction perpendicular to the main shrinkage direction is 1 time to 2 times (so-called 1 time refers to the situation without stretching ), preferably 1.01 to 1.5 times. A biaxially stretched film stretched at a stretch ratio within the above range does not cause excessive heat shrinkage in the direction perpendicular to the main shrinkage direction. When , even in the height direction of the container, heat shrinkage of the film, which is the so-called longitudinal tension phenomenon, can be suppressed, so it is preferable.

The stretching temperature needs to be changed according to the glass transition temperature of the resin used or the properties required for the heat-shrinkable film, but it is generally controlled at 60°C or higher, preferably 70°C or higher, and the upper limit is 100°C or lower, preferably 90°C. The range below ℃.

Next, if necessary, in order to reduce the natural shrinkage rate or improve heat shrinkage characteristics, etc., after heat treatment or relaxation treatment at a temperature of about 50°C to 100°C, the stretched film is cooled rapidly before the molecular orientation is relaxed. , forming a heat-shrinkable film.

In addition, surface treatment or surface processing such as corona treatment, printing, coating, and vapor deposition may be performed on the third film as required, and bag-making processing or perforation processing may be performed using various solvents or heat sealing.

(layer structure)

The layer structure of the third film may be a single layer, or may be a laminated structure in order to impart surface functional properties such as lubricity, heat resistance, solvent resistance, and easy adhesion to the film surface. That is, it may be a laminate having at least one mixed resin layer. For example, when a layer (II) or (III) having a different resin composition or additives is laminated on the layer (I) made of the mixed resin of the present invention, (I)/(II), (II)/ (I)/(II), (II)/(I)/(III), (II)/(I)/(III)/(II) and other layer structure examples. In addition, the lamination ratio of each layer can be adjusted as appropriate according to the use and purpose.

In the third film, a preferable layer structure is a layer in which the layer (II) contains polylactic acid resin as a main component. In particular, the D/L ratio of the polylactic acid resin constituting the layer (II) is preferably different from the D/L ratio constituting the layer (I). In the layer (I) and the layer (II), by changing the D/L ratio and adjusting the crystallinity to be different, better shrinkage processability can be obtained.

Examples of the method for forming the laminate include a coextrusion method, a method of laminating and thermally fusing each layer after forming a film, and a method of bonding using an adhesive or the like.

The total thickness of the third film is not particularly limited whether it is a single layer or a laminated layer, but it is preferably thin from the viewpoints of transparency, shrinkage processability, raw material cost, and the like. Specifically, the total thickness of the film after stretching is 80 μm or less, preferably 70 μm or less, more preferably 50 μm or less. In addition, the lower limit of the total thickness of the film is not particularly limited, but it is preferably 20 μm or more in consideration of the handleability of the film.

(Shrinkage)

As described above, it is important that the thermal shrinkage rate of the third film in the main shrinking direction is 20% or more when immersed in 80° C. warm water for 10 seconds. A more preferable heat shrinkage rate is 30% or more.

This is an index for judging the suitability of the shrinking process in a relatively short period of time (several seconds to about ten seconds) for PET bottle shrink label applications. Currently, in the application of labeling PET bottles, as the most widely used shrinking processing machine in the industry, water vapor is used as the heating medium for shrinking processing, and the shrinking processing machine is generally called a vapor shrinking machine. In addition, the heat-shrinkable film needs to be sufficiently heat-shrinkable at as low a temperature as possible from the viewpoint of the influence of heat on the object to be wrapped. However, in the case of films with high temperature dependence and extreme shrinkage ratios due to differences in temperature, parts with different shrinkage behaviors are likely to occur due to temperature variations in the steam shrinker, resulting in shrinkage spots, wrinkles, There is a tendency for shrinkage processing to deteriorate the appearance. From the point of view of including these industrial productivity, if the thermal shrinkage rate in the main shrinkage direction of the film is 20% or more when immersed in warm water at 80°C for 10 seconds, it can fully adhere to the coating object within the shrinkage processing time. It can be combined without spots, wrinkles, and depressions, and a good shrinkage appearance can be obtained, so it is preferred. Therefore, the thermal shrinkage rate at 80° C. of the third film is more preferably 20% to 70%.

In addition, when the film of the third film is used as a heat-shrinkable label, when immersed in warm water at 80°C for 10 seconds, the heat shrinkage rate in the direction perpendicular to the main shrinking direction of the film is preferably 10% or less, more preferably 5% or less , and more preferably 3% or less. If it is a film with a heat shrinkage rate of 10% or less in the direction perpendicular to the main shrinking direction of the film, the dimension in the direction perpendicular to the main shrinking direction of the film itself will not be easily shortened after heat shrinkage, and the printed pattern or characters after shrinking will not be easily deformed. etc., and in the case of a square bottle, it is not easy to cause failures such as longitudinal tension, so it is preferred.

In addition, although the upper limit of the above-mentioned heat shrinkage is not described, since the length of the film before stretching is not shortened by heat shrinkage, the upper limit of heat shrinkage is the shrinkage rate when it becomes the length of the film before stretching.

(transparency)

Regarding the transparency of the third film, the haze value is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less when measuring a film with a thickness of, for example, 50 μm according to JIS K7105. If the haze value is 10% or less, the transparency of the film can be obtained and a display effect can be exhibited.

(tensile elongation at break)

The impact resistance of the third film can be evaluated by tensile elongation at break. Regarding the tensile elongation at break, in a tensile test at an atmosphere temperature of 0°C and a tensile speed of 100mm/min, especially in label applications, it is measured in the film drawing (flow) direction (MD), that is, with The elongation in the direction perpendicular to the main shrinkage direction is 100% or more, preferably 150% or more, more preferably 200% or more. If the tensile elongation at break is 100% or more at an ambient temperature of 0° C. and a tensile speed of 100 mm/min, it is less likely to cause defects such as film breakage in processes such as printing and bag making, so it is preferable. In addition, when the tension applied to the film increases as the speed of processes such as printing and bag making increases, it is preferable that the tensile elongation at break is 150% or more because it is difficult to break. The upper limit is not particularly limited, but considering the current process speed, about 500% is considered sufficient, and if excessive elongation is imparted, the rigidity of the film tends to decrease on the contrary.

<4th heat-shrinkable film>

The fourth heat-shrinkable film of the present invention (hereinafter, also referred to as "the fourth film") has a polylactic acid resin (A), a (meth)acrylic resin (B) and a rubber-like component (C). (I) layer made of mixed resin, and at least two layers (II) layer mainly composed of polylactic acid resin (A), stretched in at least one direction, and has a predetermined shrinkage film.

(Amount of (meth)acrylic resin (B) added)

The amount of (meth)acrylic resin (B) added to the fourth film is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more. In addition, the added amount is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less. When the content of the (meth)acrylic resin is 5% by mass or more, the effect of improving the shrinkage characteristics, shrinkage processability, and transparency of the film can be sufficiently obtained. On the other hand, if the above-mentioned content is 30% by mass or less, the impact resistance of the film will not be significantly reduced, and the stretchability and shrinkage properties at low temperatures can be maintained, and the practical temperature range (about 70 to 90°C) can be sufficiently obtained. The thermal shrinkage rate is therefore preferred.

(Amount of rubber-like component (C) added)

The amount of the rubber-like component (C) added to the fourth film is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, with respect to the total amount of mixed resin constituting the layer (I), and It is 50 mass % or less, Preferably it is 40 mass % or less, More preferably, it is 30 mass % or less. If the added amount is 5% by mass or more, the effect of improving the impact resistance can be exhibited, and if it is 50% by mass or less, the rigidity and transparency of the film will not be impaired, and it can be used suitably as a heat-shrinkable label.

(other added ingredients)

In addition, the above-mentioned other additive components can also be added as needed. Specifically, the above-mentioned other thermoplastic resin may be mixed with the above-mentioned mixed resin constituting the (I) layer. In addition, in the above-mentioned resin constituting the layer (II), resins other than the above-mentioned other thermoplastic resins and the like may be mixed within the range that does not impair the effect of the invention.

In addition, in the above-mentioned (I) layer and (II) layer, in order to improve the impact resistance, transparency, moldability, and various properties of the heat-shrinkable film, it may also be within the range that does not significantly impair the effect of the fourth film. The various plasticizers mentioned above are added.

When adding the above-mentioned plasticizer, it is particularly preferable to add only in (I) layer. It is also possible to add a plasticizer to the (II) layer, but in this case, it is difficult to add an amount sufficient to exhibit an effect because there is a fear of precipitation of the plasticizer over time. The above-mentioned worrying characteristics such as precipitation of the plasticizer over time, specifically, blocking of the film, changes in lubricity, and poor appearance, etc., become prominent.

In the fourth film, in addition to the above-mentioned components, various additives other than the above-mentioned ones may be appropriately added within the range that does not significantly impair the effect of the fourth film.

(laminated structure)

If the structure of the fourth film includes (I) layer composed of mixed resin containing polylactic acid resin (A), (meth)acrylic resin (B) and rubber-like component (C) as described above, and the above-mentioned There are at least two layers of the (II) layer mainly composed of the (A) layer, and the layer structure is not particularly limited. The properties of the heat-shrinkable film, especially the shrinkage properties, can be easily adjusted by laminating the (II) layer mainly composed of polylactic acid resin in addition to the (I) layer.

For the fourth film, in order to improve shrinkage characteristics, the shrinkage characteristics and fracture resistance can be further improved by laminating layers (I) and (II) having different D body contents.

As a specific D/L ratio, under the above relationship, the D/L ratio of the lactic acid resin constituting the (I) layer is preferably 5/95 to 15/85 or 85/15 to 95/5, and more preferably 7/15. 93~13/87 or 87/13~93/7. In addition, the D/L ratio of the lactic acid resin constituting the (II) layer is preferably 5/95 to 10/90 or 90/10 to 95/5, more preferably 6/94 to 9/91 or 91/9 to 94 /6. As mentioned above, by adjusting the D/L ratio of the (I) layer and (II) layer, the degree of crystallinity can be controlled within an appropriate range, and defects such as shrinkage unevenness caused by crystallization can be suppressed, and at the same time, Get better shrink processability.

In addition, the so-called "having at least two layers (I) and (II) layers" is not only a form in which the (II) layer is laminated on one or both sides adjacent to the (I) layer, but also in order to provide the (I) layer and ( II) Improvement of adhesion between layers, barrier properties, concealment properties, heat insulation properties, etc., including the case of having a third layer. Preferably, a layer structure ((II) layer/(I) layer/(II) layer) of two types of layers ((II) layer/(I) layer/(II) layer) having the (I) layer as the middle layer and the (II) layer as the surface layer, or in the middle A layer structure such as a layer structure of three types of five layers ((II) layer/adhesive layer/(I) layer/adhesive layer/(II) layer) with an adhesive layer between the layer and the surface layer.

In the fourth film, the most suitable laminated structure is a two-type three-layer structure of "(II) layer/(I) layer/(II) layer". This is because the surface adjustment can be performed more easily by using the (II) layer mainly composed of the polylactic acid resin (A) as the surface layer.

(thickness)

In the fourth film, the lamination ratio of each layer is not particularly limited, but the ratio of the (I) layer is preferably 50% to 95%, more preferably 60% to 90% with respect to the overall thickness. When the layer (I) is within the above range, fracture resistance and shrinkage processability are good.

The total thickness of the fourth film is not particularly limited, but it is preferably thin from the viewpoints of transparency, shrinkage processability, raw material cost, and the like. Specifically, the total thickness of the film after stretching is 80 μm or less, preferably 70 μm or less, more preferably 50 μm or less. In addition, the lower limit of the total thickness of the film is not particularly limited, but it is preferably 20 μm or more in consideration of the handleability of the film.

(Manufacturing method)

The fourth thin film can be produced by a known method. The form of the film may be either flat or tubular, but it is preferably flat from the standpoint of productivity (chitin can be taken as a product in the width direction of the roll film) or printing on the inner surface. shape. As a method for producing a planar film, for example, melting the resin using multiple extruders, co-extruding from a T-die, cooling and solidifying with a cold roll, rolling and stretching in the longitudinal direction, and stretching in the transverse direction Stretching with a tenter, annealing, cooling, (corona discharge treatment is applied to the surface when printing), and winding with a coiler to obtain a film. In addition, a method of cutting a film produced by a tubular method to form a planar shape may also be used.

In applications that shrink in two directions such as lamination, the stretch ratio is 2 to 10 times in the longitudinal direction and 2 to 10 times in the transverse direction, preferably 3 to 6 times in the longitudinal direction and 3 times in the transverse direction ~ About 6 times. On the other hand, in applications such as heat-shrinkable labels that mainly shrink in one direction, it is desirable to select a magnification ratio that is substantially in the uniaxial stretching range as follows, that is, the direction corresponding to the main shrinking direction 2 to 10 times, preferably 4 to 8 times, and 1 to 2 times in the direction perpendicular to the main shrinkage direction, preferably 1.01 to 1.5 times. In addition, 1 time means the case where it is not stretched.

A biaxially stretched film stretched at a stretch ratio within the above range does not cause excessive heat shrinkage in the direction perpendicular to the main shrinkage direction. When , even in the height direction of the container, heat shrinkage of the film, which is the so-called longitudinal tension phenomenon, can be suppressed, so it is preferable.

The stretching temperature needs to be changed according to the glass transition temperature of the resin used or the properties required for the heat-shrinkable film, but it is generally controlled at 60°C or higher, preferably 70°C or higher, and the upper limit is 100°C or lower, preferably 90°C. The range below ℃. In addition, depending on the characteristics of the resin used, the stretching method, the stretching temperature, the shape of the target product, etc., it is 1.5 to 10 times in the main shrinkage direction, preferably 3 to 7 times, and more preferably 3 to 5 times. The stretching ratio is appropriately determined in the uniaxial or biaxial direction in the range of less than 10 times. In addition, when uniaxially stretching in the transverse direction, it is also effective to provide a weak stretch of about 1.05 times to 1.8 times in the longitudinal direction in order to improve the mechanical properties of the film. Next, if necessary, in order to reduce the natural shrinkage rate or improve heat shrinkage characteristics, etc., after heat treatment or relaxation treatment at a temperature of about 50°C to 100°C, the stretched film is cooled rapidly before the molecular orientation is relaxed. , forming a heat-shrinkable film.

(processing)

In addition, if necessary, surface treatment or surface processing such as corona treatment, printing, coating, and vapor deposition may be performed on the fourth film, and bag-making processing or perforation processing may be performed using various solvents or heat sealing.

The fourth film is processed from a planar shape into a cylindrical shape according to the object to be packaged, and is provided for packaging. When printing on cylindrical containers such as PET bottles, you can first print the required image on one side of the wide flat film rolled on the roll, then cut it to the required width, and fold it at the same time. Make the printing surface on the inside, and then seal the center to form a cylindrical shape. At this time, the shape of the sealing portion is a so-called envelope.

As the above-mentioned center sealing method, an adhesion method using an organic solvent, a method using heat sealing, a method using an adhesive, and a method using an impulse sealer are considered. Among them, from the viewpoint of productivity and appearance, it is preferable to use an adhesion method using an organic solvent.

(Shrinkage)

As described above, when the fourth film is immersed in warm water at 80° C. for 10 seconds, the heat shrinkage rate in the main shrinkage direction is 20% or more. A more preferable heat shrinkage rate is 30% or more. This is an index for judging the suitability of the shrinking process in a relatively short period of time (several seconds to about ten seconds) for PET bottle shrink label applications.

At present, in the application of labeling PET bottles, as the shrinking processing machine that is most used industrially, it is a shrinking processing machine that uses water vapor as a heating medium for shrinking processing, and is generally called a steam shrinking machine. In addition, the heat-shrinkable film needs to be sufficiently heat-shrinkable at as low a temperature as possible from the viewpoint of the influence of heat on the object to be wrapped. However, in the case of a film whose temperature dependence is high and extreme shrinkage varies depending on the temperature, parts with different shrinkage behaviors tend to occur due to temperature unevenness in the steam shrinking machine, resulting in uneven shrinkage, wrinkles, Dents, etc., tend to deteriorate the appearance of shrinkage processing. From the point of view of also including these industrial productivity, if the thermal shrinkage rate in the main shrinkage direction of the film is 20% or more when immersed in warm water at 80°C for 10 seconds, it can fully bond with the object to be coated within the shrinkage processing time. Bonding, and no spots, wrinkles, or depressions, can obtain a good shrinkage processing appearance, so it is preferred. Therefore, the shrinkage ratio of the fourth film in the film main shrinkage direction at 80° C. is more preferably 20% to 70%.

In addition, although the upper limit of the above-mentioned heat shrinkage is not described, since the length of the film before stretching is not shortened by heat shrinkage, the upper limit of heat shrinkage is the shrinkage ratio when the film length before stretching is reached.

On the other hand, by keeping the shrinkage rate in the direction perpendicular to the main shrinkage direction of the film low, more excellent shrinkage processability can be obtained. When the fourth film is used as a heat-shrinkable label, when immersed in warm water at 80°C for 10 seconds, the heat shrinkage rate in the direction perpendicular to the main shrinkage direction of the film is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less. If it is a film with a thermal shrinkage rate of 5% or less in the direction perpendicular to the main shrinking direction of the film, the dimension in the direction perpendicular to the main shrinking direction of the film itself will not be easily shortened after shrinkage, and the printed pattern or characters after shrinking will not be easily deformed, etc. In addition, in the case of a square bottle, it is less likely to cause troubles such as longitudinal tension, so it is preferable. In addition, the lower limit of the heat shrinkage rate at this time is 0%.

(transparency)

Regarding the transparency of the fourth film, the haze value is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less when measured according to JIS K7105, for example, a film with a thickness of 50 μm. If the haze value is 10% or less, the transparency of the film can be obtained and a display effect can be exhibited.

(tensile elongation at break)

The impact resistance of the fourth film is evaluated by tensile elongation at break. In a tensile test at 0°C, especially for label applications, the elongation in the film drawing (flow) direction (MD) It is 100% or more, preferably 150% or more, more preferably 200% or more. If the tensile elongation at break in a 0° C. environment is 100% or more, it is less likely to cause defects such as film breakage in processes such as printing and bag making, which is preferable. In addition, when the tension applied to the film increases as the speed of printing, bag making and other processes increases, it is preferable that the tensile elongation at break is 150% or more because it is difficult to break.

The upper limit is not particularly limited, but considering the current process speed, if it is about 500%, it is considered sufficient, and if excessive elongation is applied, there is a tendency for the film rigidity (tensile elastic modulus) to decrease on the contrary. .

[use]

<Molded products, heat-shrinkable labels, and containers>

The above-mentioned first to fourth heat-shrinkable films can be processed from a planar shape into a cylindrical shape or the like according to the object to be packaged, and can be used for packaging. When printing on cylindrical containers such as PET bottles, you can first print the required image on one side of the wide flat film rolled on the roll, then cut it to the required width, and fold it at the same time. With the printing surface on the inside, seal the center (the shape of the sealed part is a so-called envelope) to form a cylinder. As the center sealing method, an adhesive method using an organic solvent, a method using heat sealing, a method using an adhesive, and a method using an impulse sealer are considered. Among them, from the viewpoint of productivity and appearance, it is preferable to use an adhesion method using an organic solvent.

Since the above-mentioned first to fourth heat-shrinkable films are excellent in film heat shrinkability, shrinkage processability, transparency, etc., their applications are not particularly limited. If necessary, other functional layers such as a printed layer and a vapor deposition layer can be laminated. And it is used as various molded products such as bottles (blow molded bottles), plates, lunch boxes, vegetable containers, and dairy product containers. Especially when the above-mentioned first to fourth heat-shrinkable films are used as heat-shrinkable labels for food containers (for example, PET bottles and glass bottles for soft drinks or food, preferably PET bottles), even if it is complicated Shapes (for example, cylinders tapering at the center, square prisms with edges, pentagonal prisms, hexagonal prisms, etc.) in which bonding is also possible, and beautifully labeled containers without wrinkles or dents can be obtained. The container to which this molded article or label is attached can be produced using a usual molding method. In addition, it is also possible to use as a container by combining the above-mentioned molded article with a molded article formed of other materials.

Since the above-mentioned first to fourth heat-shrinkable films have excellent low-temperature shrinkability and shrinkage processability, they can be preferably used in addition to heat-shrinkable label materials for plastic moldings that deform when heated at high temperatures. Materials that are extremely different from the above-mentioned first to fourth heat-shrinkable films in terms of thermal expansion coefficient or water absorption, for example, selected from polyolefin resins such as metal, porcelain, glass, paper, polyethylene, polypropylene, polybutene, and polyacrylonitrile. At least one of polyester resins such as acrylate resins, polycarbonate resins, polyethylene terephthalate, and polybutylene terephthalate, and polyamide resins as constituent materials It is used for the heat-shrinkable label material of the package (container).

Examples of materials constituting plastic packages that can utilize the above-mentioned first to fourth heat-shrinkable films include polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-acrylic Butyl ester copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), (meth)acrylic acid-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, phenolic resin, urea-formaldehyde resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin, etc. These plastic packages may be a mixture of two or more resins, or may be a laminate.

Example

Hereinafter, the present invention will be described using examples.

In addition, the measured values and evaluations shown in the Examples were performed as follows. In the examples, the pulling (flowing) direction of the laminated film is referred to as the "longitudinal" direction (or MD), and the vertical direction thereof is referred to as the "transverse" direction (or TD).

[evaluate]

(1) Heat shrinkage rate

The film was cut into a size of 100 mm in length and 100 mm in width, immersed in a warm water bath at 60° C. or 80° C. for 10 seconds, and the amount of shrinkage was measured. The thermal shrinkage rate is expressed in % as the ratio of the amount of shrinkage relative to the original dimension before shrinkage in the direction which is larger in the longitudinal direction or the transverse direction.

(2) ΔHm-ΔHc

Using a differential scanning calorimeter DSC-7 manufactured by Parkin-Elmer, according to JIS K7121, a 10 mg sample was heated from -40°C to 250°C at a heating rate of 10°C/min. From the obtained temperature curve, the amount of heat ΔHm required to melt all the crystals and the amount of heat ΔHc generated with crystallization during temperature rise measurement were determined.

◎: ΔHm-ΔHc below 15J/g

○: ΔHm-ΔHc exceeds 15J/g and is less than 25J/g

×: ΔHm-ΔHc exceeds 25J/g

(3) Dynamic viscoelasticity measurement

The film to be measured was cut into a size of 60 mm in length and 4 mm in width, and was measured at a vibration frequency of 10 Hz, a deformation of 0.1%, and a heating rate of 1° C./min., the pitch of chucks is 2.5 cm, and the measurement temperature is measured in the longitudinal direction within the range of 0 to 150° C., and the storage elastic modulus at 70° C. is measured.

(4) Haze value

The haze value of a film having a film thickness of 50 μm was measured according to JIS K7105.

(5) Tensile elongation at break

According to JIS K7127, it is measured in the direction perpendicular to the main shrinkage direction of the film (longitudinal direction) under the conditions of a temperature of 23°C and the following test speed.

·1st film, 3rd film, 4th film...Test speed: 100mm/min

·The second film...Test speed: 200mm/min

In addition, in the 3rd film and the 4th film, the obtained film is cut into the direction (longitudinal direction) perpendicular to the main shrinkage direction of the film to be 110 mm, and the size of 15 mm in the main shrinkage direction is used. The measurement was performed at 0° C., and the average value of ten measurements was obtained.

(6) Tensile modulus of elasticity

According to JIS K7127, it is measured in the direction perpendicular to the main shrinkage direction of the film (longitudinal direction) at a temperature of 23°C.

(7) shrinkage processability

"For the 1st Film"

The film printed at a grid interval of 10 mm was cut into a size of 100 mm in length and 298 mm in width, and both lateral ends were overlapped by 10 mm, and bonded using tetrahydrofuran (THF) solvent to prepare a cylindrical film. Attach this cylindrical film to a cylindrical PET bottle with a capacity of 1.5 L, and pass it in about 4 seconds without rotating the 3.2m long (3 zones) shrinking channel of the steam heating method . The amount of steam was adjusted using a steam valve so that the temperature of the atmosphere in the tunnel in each zone was in the range of 70 to 85°C. Evaluation was performed according to the following criteria after film coating.

◎: The shrinkage is sufficient, and there are no wrinkles, dents, or mesh distortions at all

○: Sufficient shrinkage, slightly wrinkled, sunken, and grid skewed

×: Insufficient shrinkage, or significant wrinkles, dents, and mesh distortion

"For the 2nd Film"

The film printed with a grid interval of 10 mm was cut into a size of 170 mm in length (MD) × 114 mm in width (TD), and the two ends of TD were overlapped by 10 mm, and bonded using tetrahydrofuran (THF) solvent to prepare a cylindrical film. Attach this cylindrical film to a cylindrical PET bottle with a capacity of 500mL, and pass it through the 3.2m-long (3-zone) shrinking channel of the steam heating method in about 4 seconds without rotation, And thus coated on the container. The amount of steam was adjusted using a steam valve so that the temperature of the atmosphere in the tunnel in each zone was in the range of 60 to 90°C. The atmospheric temperature at this time is shown below.

Coating condition 1...65℃/80℃/80℃

Coating condition 2...90℃/90℃/60℃

Coating condition 3...75℃/85℃/85℃

Evaluation was performed according to the following criteria after film coating.

◎: Shrinkage is sufficient, and there are no wrinkles, dents, whitening, and grid skewing at all

○: Sufficient shrinkage, slightly wrinkled, sunken, whitened, and grid skewed, but practically no problem

△: Sufficient shrinkage, slightly wrinkled, sunken, whitened, mesh skewed, causing problems in some applications

×: Insufficient shrinkage, or significant wrinkles, dents, and mesh distortion

"For the 3rd Film"

Cut the film printed into a grid with an interval of 10mm into a size of MD170mm×TD114mm, overlap the two ends of TD by 10mm, and bond using tetrahydrofuran (THF) solvent to prepare a cylindrical film. Attach this cylindrical film to a cylindrical PET bottle with a capacity of 500mL, and pass it through the 3.2m-long (3-zone) shrinking channel of the steam heating method in about 4 seconds without rotation, And thus coated on the container. The amount of steam was adjusted using a steam valve so that the temperature of the atmosphere in the tunnel in each zone was in the range of 70 to 90°C.

Evaluation was performed according to the following criteria after film coating.

◎: Shrinkage is sufficient, and there are no wrinkles, dents, whitening, and grid skewing at all

○: Sufficient shrinkage, slightly wrinkled, sunken, whitened, and grid skewed, but practically no problem

△: Sufficient shrinkage, slightly wrinkled, sunken, whitened, mesh skewed, causing problems in some applications

×: Insufficient shrinkage, or significant wrinkles, dents, and mesh distortion <For the 4th film>

Cut the film printed into a grid with an interval of 10mm into a size of MD170mm×TD114mm, overlap the two ends of TD by 10mm, and bond using tetrahydrofuran (THF) solvent to prepare a cylindrical film. Attach this cylindrical film to a cylindrical PET bottle with a capacity of 500mL, and pass it through the 3.2m-long (3-zone) shrinking channel of the steam heating method in about 4 seconds without rotation, And thus coated on the container. The amount of steam was adjusted using a steam valve so that the temperature of the atmosphere in the tunnel in each zone was in the range of 70 to 85°C.

Evaluation was performed according to the following criteria after film coating.

◎: Shrinkage is sufficient, and there are no wrinkles, dents, whitening, and grid skewing at all

○: Sufficient shrinkage, slightly wrinkled, sunken, whitened, and grid skewed, but practically no problem

△: Sufficient shrinkage, slightly wrinkled, sunken, whitened, mesh skewed, causing problems in some applications

×: Insufficient shrinkage, or significant wrinkles, dents, and skewed grids

[raw material]

In addition, the raw materials used in each Example and a comparative example are as follows.

(Polylactic acid resin (A))

Polylactic acid resin...manufactured by Nature Works LLC, trade name "NatureWorkNW4050", L body/D volume = 95/5, hereinafter referred to as "PLA1";

Polylactic acid resin...manufactured by Nature Works LLC, trade name "NatureWorkNW4032", L body/D volume = 99.5/0.5, hereinafter referred to as "PLA2";

· Polylactic acid-based resin...manufactured by Nature Works LLC, trade name "NatureWorkNW4060", L body/D volume = 88/12, hereinafter abbreviated as "PLA3".

((meth)acrylic resin (B))

・Polymethyl methacrylate resin...manufactured by Sumitomo Chemical Co., Ltd., trade name "Sumipex LG21", hereinafter referred to as "PMMA1";

・Polymethyl methacrylate resin...Manufactured by Mitsubishi Rayon Co., Ltd., trade name "Acrypet VH01", hereinafter referred to as "PMMA2";

・Acrylic resin...manufactured by Mitsubishi Rayon Co., Ltd., trade name: Acrypet VH01, methyl methacrylate resin, hereinafter abbreviated as "VH01".

(Rubber-like component (C))

・Core-shell structure type acrylic-polysiloxane copolymer...Manufactured by Mitsubishi Rayon Co., Ltd., trade name "Metablen S2001", hereinafter referred to as "Rubber 1";

・Polylactic acid-aliphatic polyester resin...manufactured by Dainippon Ink Chemical Co., Ltd., trade name "Plamate PD150", hereinafter referred to as "Rubber 2";

・Ethylene-polyvinyl alcohol resin...manufactured by Mitsui DuPont Polymer Chemicals Co., Ltd., trade name "Ebaflex (エバフレッックス) EV45LX", hereinafter referred to as "Rubber 3";

・Aliphatic polyester resin...manufactured by Daicel Chemical Industry Co., Ltd., trade name "Celgreen PH7", hereinafter referred to as "Rubber 4";

・Aliphatic polyester resin...Manufactured by Showa Polymer Co., Ltd., trade name "Bionolle 1010", hereinafter referred to as "Rubber 5";

・Aliphatic polyester resin...Manufactured by Showa Polymer Co., Ltd., trade name "Bionolle 3003", hereinafter referred to as "Rubber 6";

· Aliphatic polyester resin ... manufactured by Mitsubishi Chemical Corporation, trade name "GS-Pla AZ91T (polybutylene succinate)", hereinafter abbreviated as "rubber 7".

(Silicone acrylic compound rubber (D))

- Silicone acrylic composite rubber ... manufactured by Mitsubishi Rayon Co., Ltd., trade name: Metablen S2001, core-shell structure acrylic-polysiloxane copolymer, hereinafter abbreviated as "S2001".

(additive)

·Polyester plasticizer...manufactured by Dainippon Ink Chemical Co., Ltd., trade name "DOZ", hereinafter referred to as "plasticizer";

· Hydrophobic silica particles... manufactured by Fuji Silysia Chemical Co., Ltd., trade name "Sylophobic (Sylophobic) 100", hereinafter abbreviated as "silica particles".

[Example for the first film]

(Example 1)

As shown in Table 1, PLA1: 50% by mass, PMMA2: 25% by mass and rubber 1: 25% by mass were put into a twin-screw extruder manufactured by Mitsubishi Heavy Industries, and the set temperature was 200 It was melt-mixed at °C, extruded using a T-die, drawn by a casting roll at 50 °C, cooled and solidified to obtain an unstretched sheet with a width of 300 mm and a thickness of 250 μm. Next, using a film tenter manufactured by Mitsubishi Heavy Industries, Ltd., at a preheating temperature of 90°C and a stretching temperature of 85°C, it was stretched 5.0 times in the transverse uniaxial direction to obtain a heat-shrinkable film with a thickness of 50 μm. film.

A film whose evaluation items are all ⊚ is evaluated as (⊚) comprehensively, a film containing ◯ is comprehensively evaluated as (◯), and a film with only one X is comprehensively evaluated as (×). The results of the evaluation are shown in Table 1.

(Example 2)

As shown in Table 1, in Example 1, except that rubber 1 was changed to rubber 2, and the composition ratio was changed to PLA1: 60% by mass, PMMA1: 15% by mass, rubber 2: 25% by mass, and Example 1 A heat-shrinkable film was obtained in the same manner. Table 1 shows the evaluation results of the obtained film.

(Example 3)

As shown in Table 1, a heat-shrinkable film was obtained in the same manner as in Example 2 except that the rubber 1 was not included in Example 1, and the composition ratio was changed to PLA1:60% by mass and PMMA1:40% by mass. Table 1 shows the evaluation results of the obtained film.

(Example 4)

As shown in Table 1, in Example 1, in addition to containing PLA2, and changing the composition ratio to PLA1: 30% by mass, PLA2: 20% by mass, PMMA1: 25% by mass, rubber 1: 25% by mass, and In Example 1, a heat-shrinkable film was obtained in the same manner. Table 1 shows the evaluation results of the obtained film.

(Example 5)

As shown in Table 1, in Example 4, in addition to using two types of 3-layer feed blocks (Fierd Block), on both sides of the mixed resin layer (indicated as "middle layer" in Table 1) with the same composition ratio, A mixed resin layer (expressed as "outer layer" in Table 1) in which 0.3 parts by mass of silica particles were added to 100 parts by mass of PLA1:90 mass% and PMMA1:10 mass% of the mixed resin was coextruded, A heat-shrinkable film was obtained in the same manner as in Example 3, except that the thickness ratio was adjusted to outer layer: middle layer: outer layer = 30 μm: 190 μm: 30 μm. Table 1 shows the evaluation results of the obtained film.

(Example 6)

As shown in Table 1, in Example 1, in addition to changing rubber 1 to rubber 3, changing the composition ratio to PLA1: 45% by mass, PMMA1: 25% by mass, rubber 3: 30% by mass, and Example 1 A heat-shrinkable film was obtained in the same manner. Table 3 shows the evaluation results of the obtained film.

(comparative example 1)

As shown in Table 1, in Example 1, except that the composition ratio was changed to PLA1:75% by mass, rubber1:25% by mass, and PMMA1 was not included, a heat-shrinkable film was obtained in the same manner as Example 1. Table 1 shows the evaluation results of the obtained film.

(comparative example 2)

As shown in Table 1, in Example 4, except that the composition ratio was changed to PLA1: 55% by mass, PLA2: 20% by mass, rubber 1: 25% by mass, and PMMA1 was not contained, the same method was obtained as in Example 4. Heat shrinkable film. Table 1 shows the evaluation results of the obtained film.

(comparative example 3)

As shown in Table 1, in Example 1, except that the composition ratio was changed to PLA1: 35% by mass, PMMA1: 40% by mass, and rubber 1: 25% by mass, a heat-shrinkable film was obtained in the same manner as in Example 1. , but broke during the stretching of the sheet.

(comparative example 4)

As shown in Table 1, in Example 1, except having changed the composition ratio into PLA1:73 mass%, PMMA1:2 mass%, rubber 1:25 mass%, it carried out similarly to Example 1, and obtained the heat-shrinkable film. Table 1 shows the evaluation results of the obtained film.

[Table 1]

Example Comparative example 1 2 3 4 5 6 1 2 3 4 raw material Middle (A) Ingredients PLA1 (parts by mass) 50 60 60 30 30 45 75 55 35 73 PLA2 (parts by mass) 20 20 20 (B) Ingredients PMMA1 (parts by mass) 25 15 40 25 25 25 40 2 (C) Ingredients Rubber 1 (parts by mass) 25 25 25 25 25 25 25 Rubber 2 (parts by mass) 25 Rubber 3 (parts by mass) 30 outer layer (A) Ingredients PLA1 (parts by mass) 90 (B) Ingredients PMMA1 (parts by mass) 10 Silica particles (parts by mass) 0.3 Physical properties and evaluation Heat shrinkage 60℃(%) 7 1 8 1 0 6 3 4 unable to stretch due to break 2 80℃(%) 68 50 78 63 68 65 16 17 twenty one ΔHm-ΔHc(J/g) 5◎ 11◎ 6◎ 12◎ 13◎ 6◎ 29× 34× 26× shrinkage processability ◎ ◎ ○ ○ ◎ ◎ × × × Low temperature tensile elongation at break (%) 188 202 4 222 154 223 432 343 386 Overview ◎ ◎ ○ ○ ◎ ◎ × × ×

(result)

As can be seen from Table 1, the films of Examples 1 to 6 having the mass ratio of the polylactic acid resin (A) to the (meth)acrylic resin (B) specified in the first film have better shrinkage processability than those of Comparative Examples. . Conversely, when the (meth)acrylic resin (B) was not contained (comparative examples 1 and 2), the shrinkage processability was poor, and the polylactic acid resin (A) and (a In the case of the acrylic resin (B) (Comparative Examples 3 and 4), stretchability and shrinkage processability deteriorated. In addition, when rubber components are contained (Examples 1, 2, 4 to 6) and rubber components are not included (Example 3), it can be seen that the elongation at break at low temperature (that is, impact resistance) when rubber components are contained Better than without the rubber component.

From this, it can be seen that the first film is a heat-shrinkable film that is excellent in heat-shrinkable properties and suitable for applications such as shrink packaging, shrink-bundling packaging, and heat-shrinkable labels.

[Example for the second film]

(Examples 7-10, Comparative Examples 5-7)

As shown in Table 2, the mixed resin of (A) component, (B) component and (C) component as the resin for (I) layer was charged into a twin-screw extruder (manufactured by Mitsubishi Heavy Industries, Ltd.), and the The temperature was set at 200° C., melted and mixed, extruded using a T-die, drawn by a casting roll at 50° C., cooled and solidified to obtain an unstretched sheet with a width of 300 mm and a thickness of 250 μm. Next, using a film tenter (manufactured by Mitsubishi Heavy Industries, Ltd.), stretch 5.0 times in the transverse uniaxial direction at a preheating temperature of 90°C and a stretching temperature of 75°C to obtain a heat-shrinkable film with a thickness of 50 μm. sex film. Table 2 shows the physical properties and evaluation results of the obtained film.

In addition, the resin for layer (II) shown in Table 2 contains polylactic acid-based resin and silica particles, and by the co-extrusion method using two kinds of 3-layer feed tables, the mixed resin layer Resin layers for the (II) layer were formed on both surfaces of each to produce unstretched laminated sheets having respective predetermined thickness ratios. This unstretched laminated sheet was formed into a heat-shrinkable film having a thickness of 50 μm by the same method as described above.

[Table 2]

Example Comparative example 7 8 9 10 5 6 7 raw material (I) layer (A) Ingredients PLA1 (parts by mass) 100 100 100 100 100 100 PLA2 (parts by mass) 100 D/L ratio 5/95 5/95 5/95 5/95 5/95 5/95 0.5/99.5 (B) Ingredients PMMA2 (parts by mass) 65 35 100 115 15 250 (C) Ingredients Rubber 1 (parts by mass) 55 35 50 Rubber 4 (parts by mass) 15 Rubber 5 (parts by mass) 20 Rubber 6 (parts by mass) 30 other Plasticizer (parts by mass) 12 8 8 4 (II) layer PLA1 (parts by mass) 100 40 D/L ratio 5/95 PLA3 (parts by mass) 60 D/L ratio 12/88 Silica particles (parts by mass) 0.3 layer structure (I) (II)/(I)/(II) (I) Thickness ratio (II) layer 30 30 (I) layer 250 250 190 190 250 250 250 (II) layer 30 30 Physical properties and evaluation 80°C Shrinkage (%) 50 45 43 45 40 unable to stretch due to break 4   70°C storage modulus (E’) (MPa) 550 120 800 820 40 1100   Tensile elongation at break (%) 262 322 230 300 420 243 shrinkage processability (Cladding condition 1) ○ ○ ○ ○ △ × (Cladding condition 2) ○ ○ ◎ ◎ ○ × (Cladding condition 3) ○ ○ ○ ◎ △ × Haze value (%) 3 3 3 3 3 27   Tensile modulus of elasticity (GPa) 2.3 2.3 2.4 2.6 2.3 2.9

(result)

As can be seen from Table 2, a film having the composition, thermal shrinkage rate, and storage modulus (E') specified in the second film is excellent in transparency, tensile elongation at break, transparency, and shrinkage processability. On the contrary, when the (meth)acrylic resin is small (Comparative Example 5), the storage elastic modulus (E') and shrinkage processability are poor, and when the (meth)acrylic resin is large (Comparative Example 6), the film breaks and cannot The mechanical properties and shrinkage processability were determined. In addition, when the (meth)acrylic resin was not contained (Comparative Example 7), the shrinkage rate was low, and shrinkage processability was considerably poor.

From this, it can be seen that the film of the second film is excellent in mechanical properties such as heat shrinkability, transparency, and impact resistance, and also excellent in shrinkage processability.

[Example for the 3rd film]

(Examples 11-17, Comparative Examples 8-10)

The mixed resin obtained by mixing polylactic acid resin (A), polysiloxane acrylic compound rubber (D) and other resin additives shown in Table 3 was put into a twin-screw extruder (manufactured by Mitsubishi Heavy Industries, Ltd. ), melted and mixed at a set temperature of 200°C, extruded from a die set at 200°C, pulled by a casting roll at 50°C, cooled and solidified to obtain an unstretched sheet.

Next, use a roll longitudinal stretching machine to stretch in the longitudinal direction under the conditions of Table 3, and then use a film tenter (manufactured by Kyoto Machinery Co., Ltd.) to stretch in the transverse direction under the conditions of Table 3 to obtain heat Shrink film. Table 3 shows the evaluation results of the obtained film.

[table 3]

Example Comparative example 11 12 13 14 15 16 17 8 9 10 raw material level one Polylactic acid resin (A) PLA1 (parts by mass) 75 20 10 20 20 20 30 70 PLA3 (parts by mass) 55 50 30 50 50 30 PLA2 (parts by mass) 75 100 D/L ratio 5/95 10/90 11/89 9/91 10/90 10/90 8.5/91.5 1.5/98.5 1.5/98.5 5/95 Polysiloxane acrylic compound rubber (D) S2001 (parts by mass) 25 25 40 30 20 20 30 25 (Meth)acrylic resin (B) VH01 (parts by mass) 20 10 10 Rubber-like component (C) Rubber 7 (parts by mass) 10 10 30 Second floor polylactic acid resin PLA1 (parts by mass) 25 PLA3 (parts by mass) 75 D/L ratio 10/90 Stretch condition longitudinal stretch Stretching temperature (℃) 60 60 60 66 60 63 63 60 60 60 Magnification (times) 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 lateral stretch Preheating temperature (℃) 68 68 68 78 68 72 72 68 68 68 Stretching temperature (℃) 63 63 63 73 63 69 69 63 63 63 Magnification (times) 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Film thickness (μm) 50 50 50 50 50 50 50 50 50 50 evaluate Heat shrinkage rate (%) vertical 4 1 2 -2.5 0.5 -2 0 5 4 4 horizontal 34 37 37 41 43 40 40 30 34 36 Haze value%) 4.6 4.5 4.9 4.5 5.1 5.2 4.4 4.6 4.6 40～50   Tensile elongation at break (%) (0°C) 352 318 376 247 334 225 287 352 45 89   Shrinkage processability ○ ○ ○ ◎ ○ ◎ ◎ × △ ○

(result)

As can be seen from Table 3, the film including the composition specified in the third film has mechanical properties such as thermal shrinkage properties, tensile elongation at break, transparency, and shrink processability. On the contrary, when the D/L ratio is out of the range of the present invention (Comparative Example 8), shrinkage workability is poor. Furthermore, when the silicone acrylic compound rubber was not contained (Comparative Examples 9 and 10), the impact resistance was poor.

From this, it can be seen that the third film is a heat-shrinkable film excellent in mechanical properties such as heat shrinkability, impact resistance, and transparency, and shrinkage processability.

[Example for the 4th film]

(Examples 18-21, Comparative Examples 11-12, Reference Examples)

A mixed resin obtained by mixing a polylactic acid resin (A), a (meth)acrylic resin (B), and a rubber-like component (C) (for a comparative example, a polylactic acid-based resin (A) or a rubber-like Two kinds of mixed resins selected from the component (C)) are used as the resin for the (I) layer shown in Table 4. In addition, the resin mainly composed of polylactic acid resin (A) is used as the (I) layer shown in Table 4. II) Resins for the layer, which were put into different twin-screw extruders (manufactured by Mitsubishi Heavy Industries, Ltd.), melted and mixed at a set temperature of 200°C, and two kinds of resins with a set temperature of 200°C were used. After the three-layer die was extruded into a "(II)/(I)/(II)" structure, it was pulled by a casting roll at 50°C, cooled and solidified to obtain an unstretched sheet with a width of 300 mm and a thickness of 200 μm.

Then, using a roll longitudinal stretching machine, stretching in the longitudinal direction under the conditions of Table 4, and then using a film tenter (manufactured by Mitsubishi Heavy Industries, Ltd.), stretching in the transverse direction under the conditions of Table 4 to obtain a heat Shrink film. Table 4 shows the evaluation results of the obtained film.

[Table 4]

Example Comparative example Reference example 18 19 20 twenty one 11 12 raw material (I) layer (A) Ingredients PLA1 (parts by mass) 10 10 55 10 15 15 40 PLA3 (parts by mass) 45 45 45 60 65 15 D/L ratio 10.7 10.7 5.0 10.7 12.0 12.0 6.9 (B) Ingredients PMMA2 (parts by mass) 20 20 20 20 20 20 (C) Ingredients Rubber 1 (parts by mass) 25 25 25 25 Rubber 6 (parts by mass) 25 25 (II) layer (A) Ingredients PLA1 (parts by mass) 50 50 50 40 50 50 40 PLA3 (parts by mass) 50 50 50 40 50 50 15 D/L ratio 8.5 8.5 8.5 8.5 8.5 8.5 6.9 (B) Ingredients PMMA2 (parts by mass) 20 20 (C) Ingredients Rubber 6 (parts by mass) 25 Stretch condition longitudinal stretch Stretching temperature (℃) 66 66 66 66 60 66 65 Magnification (times) 1.05 1.05 1.05 1.05 1.05 1.05 1.05 lateral stretch Preheating temperature (℃) 78 78 78 78 68 78 75 Stretching temperature (℃) 73 73 73 73 63 73 71 Magnification (times) 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Film thickness (μm) 50 50 50 50 50 50 50 evaluate Heat shrinkage vertical(%) -2 -3 0 -3 7 -1 -2 horizontal(%) 40 40 4 1 39 44 40 42 Haze value (%) 3.6 3.9 3.5 3.8 4.2 4.7 11.9   Tensile elongation at break (%) (0°C) 288 257 267 210 295 6 220   Shrinkage processability ○ ○ ○ ○ × ○ ○

(result)

As can be seen from Table 4, the film containing the composition and the like specified in the fourth film has good impact resistance, transparency, and shrinkage processability. On the contrary, when the film of (meth)acrylic resin (B) was not included (Comparative Example 11), the shrinkage processability was inferior, and when the rubber-like component (C) was not included (Comparative Example 12), the impact resistance was inferior. In addition, as is clear from Examples 18 to 21 and Reference Examples, good transparency can be obtained by adjusting the D/L ratio of the polylactic acid-based resin (A) contained in the (I) layer and (II) layer.

From this, it can be seen that the fourth film is a heat-shrinkable film that is excellent in heat-shrinkable properties, mechanical properties such as impact resistance and transparency, and shrinkable processability, and is suitable for shrink packaging, shrink-bundling packaging, and shrinkable labels. film.

Industrial Applicability

Since the film of the present invention is excellent in heat-shrinkable properties, it can be used in various applications such as various shrink packages, shrink-bundled packages, and shrink labels.

In addition, Japanese Patent Application No. 2005-138437 filed on May 11, 2005, Japanese Patent Application No. 2005-358106 filed on December 12, 2005, Japanese Patent Application No. 2005-378969 filed on December 28, 2005, and The specification, claims, drawings, and abstract of Japanese Patent Application No. 2005-379196 are used in their entirety as the disclosure content of the specification of the present invention.

Claims (14)

1. heat-schrinkable film; This film is by containing polylactic acid resin (A) and (methyl) acrylics (B) is processed as the hybrid resin of principal constituent; Perhaps has this hybrid resin layer of one deck at least; Wherein, the mass ratio of polylactic acid resin (A) and (methyl) acrylics (B) is (A)/(B)=95/5～33/67 in the hybrid resin; Said heat-schrinkable film also contains rubber-like composition (C), and dipping is during 10 seconds in 80 ℃ of warm water, and the percent thermal shrinkage of film master shrinkage direction is more than 20%,

Said rubber-like composition (C) is at least a in multipolymer, core shell structure type rubber, ethylene-vinyl acetate copolymer, ethene-(methyl) PEMULEN TR2, ethylene-ethyl acrylate copolymer and ethene-(methyl) methyl acrylate copolymer that is selected from lactic acid analog copolymer, aliphatic polyester, aromatic series aliphatic polyester, aromatic polyester, two pure and mild dicarboxylicacid and lactic acid homopolymer except that polylactic acid resin (A)

And said rubber-like composition (C) is 3～45 quality % with respect to the content of whole hybrid resins.

2. the described heat-schrinkable film of claim 1; Wherein, Use differential scanning calorimeter (DSC) and with 10 ℃/minute rate of heating when-40 ℃ are warming up to 250 ℃, for poor (the Δ Hm-Δ Hc) that fuse the necessary heat Δ of the whole crystallizations Hm that contains in the film and the heat Δ Hc that produces by crystallization in measuring of heating up for below the 25J/g.

3. the described heat-schrinkable film of claim 1 wherein, uses the visco-elasticity spectrometer, when under the condition of vibrational frequency 10Hz, distortion 0.1%, measuring, with storage modulus under on the main shrinkage direction vertical direction 70 ℃ (E ') be 100MPa～1.5GPa.

4. the described heat-schrinkable film of claim 1, wherein, polylactic acid resin (A) is the multipolymer of D-lactic acid and L-lactic acid, or the mixture of this multipolymer.

5. the described heat-schrinkable film of claim 2, wherein, polylactic acid resin (A) is the multipolymer of D-lactic acid and L-lactic acid, or the mixture of this multipolymer.

6. the described heat-schrinkable film of claim 3, wherein, polylactic acid resin (A) is the multipolymer of D-lactic acid and L-lactic acid, or the mixture of this multipolymer.

7. the described heat-schrinkable film of claim 3, wherein, based on JIS K7127, the draw speed that divides at 23 ℃, 200mm/ is down during mensuration, with tension fracture elongation rate on the main shrinkage direction vertical direction be more than 100%.

8. the described heat-schrinkable film of claim 4, wherein, based on JIS K7127, the draw speed that divides at 23 ℃, 200mm/ is down during mensuration, with tension fracture elongation rate on the main shrinkage direction vertical direction be more than 100%.

9. the described heat-schrinkable film of claim 5, wherein, based on JIS K7127, the draw speed that divides at 23 ℃, 200mm/ is down during mensuration, with tension fracture elongation rate on the main shrinkage direction vertical direction be more than 100%.

10. the described heat-schrinkable film of claim 6, wherein, based on JIS K7127, the draw speed that divides at 23 ℃, 200mm/ is down during mensuration, with tension fracture elongation rate on the main shrinkage direction vertical direction be more than 100%.

11. each described heat-schrinkable film in the claim 1～10; Wherein, (methyl) acrylics (B) is imperplex or is selected from the two or more monomeric multipolymer in (methyl) methyl acrylate, (methyl) ethyl propenoate, (methyl) Bing Xisuandingzhi, (methyl) vinylformic acid.

12. use the moulding article of each described heat-schrinkable film in the claim 1～11.

13. use the heat-shrinkable label of each described heat-schrinkable film in the claim 1～11.

14. post the container of described moulding article of claim 12 or the described heat-shrinkable label of claim 13.