JP2016138233A - Translucent stretched film - Google Patents

Abstract

A stretched film which is a plastic film but also has translucency, preferably has excellent printability and heat sealability, and optionally has transcribing properties such as pencil writing and hand cutting. To provide a stretched film. A translucent stretched film having a total light transmittance of 35 to 85% obtained by using a combination of at least two crystalline thermoplastic resins having a melting point and a glass transition temperature in a specific range. . [Selection figure] None

Description

  Although the present invention is a plastic film having higher moisture resistance, water resistance, oil resistance and mechanical strength than paper, it also has translucency, and preferably has excellent printability and heat sealability. The present invention relates to a stretched film having pencil writing property and hand cutting property as desired.

  Conventionally, translucent paper such as translucent paper, glassine paper, paraffin paper, and sulfuric acid paper has excellent visibility of characters and patterns printed on the surface, and the contents can be confirmed. It is used for medicine wrapping paper, food wrapping paper, cooking sheets, book covers and the like. However, it is difficult to increase the thickness of these translucent papers in order to obtain translucency, and the mechanical strength becomes insufficient because the thickness is reduced. Also, paper dust is generated during printing, cutting, packaging, and the like, which may cause problems such as deterioration in printability and cutting workability, and contamination of the package. Further, compared to plastic films, the moisture resistance, water resistance and oil resistance are low, and it may not be used for packaging of foods containing moisture and oil. Furthermore, paper generally does not have heat sealability and cannot be used in packaging forms that require heat sealability.

  On the other hand, plastic films are clearly superior in moisture resistance, water resistance, and oil resistance compared to paper, and are excellent in mechanical strength even in thin materials, and are therefore used for packaging paper for foods and medicines. However, because of its high transparency, it cannot be said that the visibility of characters and designs printed on the film surface is good, and because it is highly transparent, it is difficult to obtain a high-class feeling and design, and it is used for packaging confectionery etc. There is a problem that it is difficult to use for replacement of paper such as Japanese paper.

In addition, translucent paper generally can be torn by hand without having a cut edge or the like, and has a hand cutting property that it can be opened by hand when used in a packaging bag or the like. Yes. In addition, for transcribing paper and the like, pencil writing is required for its use.
However, a general plastic film does not have a hand cutting property unless it has a special shape such as a cut edge, and writing with a pencil or the like is impossible because the film surface is too smooth. Therefore, it may not be used as a substitute for paper.

  Patent Document 1 proposes a polypropylene biaxially stretched film having a pearly luster formed from a polypropylene resin composition containing polypropylene and specific calcium carbonate powder. Patent Document 2 is characterized in that a resin composition film comprising a crystalline olefin and a cyclic olefin-based resin is stretched at least three times in at least one direction and has a light transmittance of 50% or less. Opaque polyolefin films have been proposed.

  However, since calcium carbonate used in the polypropylene biaxially stretched film described in Patent Document 1 is opaque, a film having a translucent appearance cannot be obtained. In addition, the package may be contaminated due to dropping off of the particles, and the printing plate may be soiled for printing, and the cutting workability is not good. Furthermore, it has no hand cutting property. In addition, the opaque polyolefin-based film described in Patent Document 2 uses an amorphous cyclic olefin-based resin, is difficult to obtain a translucent appearance, and does not have a writing property or a hand cutting property with a pencil or the like. It is.

  Under such circumstances, it is a plastic film having higher moisture resistance, water resistance, oil resistance, and mechanical strength than paper, but also has translucency, and preferably has excellent printability and heat sealability. A film having pencil writing ability and hand cutting ability is desired.

JP-A-11-005852 JP-A-8-73618

  An object of the present invention is to provide a translucent stretched film, preferably a translucent stretched film having excellent printability and heat sealability, and optionally having pencil writing properties and hand cutting properties.

  As a result of paying attention to the melting point and glass transition temperature of two types of crystalline thermoplastic resins constituting the film, the present inventors have found that two types of crystalline thermoplastic resins having a melting point and a glass transition temperature satisfying a specific relational expression. It has been found that the above-mentioned problems can be solved by a translucent stretched film having a total light transmittance of 35 to 85% obtained by using a combination of the above, and the present invention has been completed.

That is, the present invention includes the following.
[1] Crystalline thermoplastic resin A and crystalline thermoplastic resin B are contained at least as resin components, melting point Tm (A) and glass transition temperature Tg (A) of crystalline thermoplastic resin A, crystalline heat A translucent stretched film having a total light transmittance of 35 to 85%, wherein the melting point Tm (B) and the glass transition temperature Tg (B) of the plastic resin B satisfy the following formulas at the same time.
Tm (B) ≧ Tm (A) + 50 ° C.
Tm (A) ≧ Tg (B) + 40 ° C.
Tg (B)> Tg (A)
[2] The translucent stretched film according to [1], containing the crystalline thermoplastic resin B in an amount of 15 to 45% by mass based on the total mass of the resin components.
[3] The translucent stretched film according to [1] or [2], wherein the ash content is 1% by mass or less based on the total mass of the film.
[4] The translucent stretched film according to any one of [1] to [3], wherein the 60 ° specular gloss is 5 to 35%.
[5] The translucent stretched film according to any one of [1] to [4], wherein Tm (A) is 135 ° C to 175 ° C.
[6] The translucent stretched film according to any one of [1] to [5], wherein Tm (B) is 200 ° C. or higher.
[7] The translucent stretched film according to any one of [1] to [6], wherein Tg (B) is 60 to 130 ° C.
[8] The translucent stretched film according to any one of [1] to [7], wherein the crystalline thermoplastic resin A is a crystalline polyolefin resin.
[9] The translucent stretched film according to any one of [1] to [8], which has a heat seal layer on at least one side.
[10] The translucent stretched film according to any one of [1] to [9], wherein the wetting tension on at least one side is 36 to 45 mN / m.
[11] A food packaging bag comprising the translucent stretched film according to any one of [1] to [10].

  The translucent stretched film of the present invention is white and translucent, and has excellent mechanical strength, moisture resistance, water resistance and oil resistance, so that it can be used for labels, tape substrates, printing substrates, poster papers, It can be suitably used for a thermal paper base, a recording paper base, and the like. In a preferred aspect of the present invention, the translucent stretched film of the present invention has excellent printability and heat sealability, and therefore can be preferably used for food packaging applications. In a preferred aspect of the present invention, the translucent stretched film of the present invention can have hand cutting properties, and therefore can be used for wrapping papers such as foods and medicines that require hand cutting properties. Further, such a translucent stretched film of the present invention seems to have an effect of containing a fine dispersion of a crystalline thermoplastic resin, but it can be written with a pencil like paper even though it does not contain inorganic particles. is there. In addition, since it does not contain inorganic particles, there is no contamination of the package due to falling off of inorganic particles, and there is no stain on the printing plate for printing applications, causing problems such as rough cutting surfaces and fast cutting blade consumption during cutting. Absent.

  The translucent stretched film of the present invention has a total light transmittance of 35% to 85%. When the total light transmittance is less than 35%, it becomes opaque and it becomes difficult to confirm the contents when used for packaging. On the other hand, if it exceeds 85%, the transparency becomes too high, and the visibility of characters and designs printed on the film surface deteriorates. The translucent stretched film of the present invention preferably has a total light transmittance of 40% to 80%, more preferably 50% to 75%, and still more preferably 52 to 70%. If the total light transmittance is within the above range, the stretched film is preferably translucent. In the present invention, the total light transmittance is a value measured in accordance with JIS-K7361, and can be measured using, for example, Nippon Denshoku Industries Co., Ltd. Haze Meter NDH-5000.

  The translucent stretched film of the present invention comprises, as resin components, a crystalline thermoplastic resin A (hereinafter referred to as crystalline resin A) which is a main resin, and a crystalline thermoplastic resin B (which is dispersed in the main resin). Hereinafter referred to as crystalline resin B). Here, the crystalline thermoplastic resin is heated at a rate of 10 ° C./min from −40 ° C. to 300 ° C. under a nitrogen flow using DSC, held at 300 ° C. for 5 minutes, and at −10 ° C./min. A thermoplastic resin in which a clear melting peak appears in the DSC curve when cooled to 40 ° C., held at −40 ° C. for 5 minutes, and then heated again to 300 ° C. at 10 ° C./min.

In the present invention, the melting point Tm (A) and the glass transition temperature Tg (A) of the crystalline resin A, and the melting point Tm (B) and the glass transition temperature Tg (B) of the crystalline resin B are expressed by the following (formula 1). (Equation 2) and (Equation 3) are simultaneously satisfied.
Tm (B) ≧ Tm (A) + 50 ° C. (Formula 1)
Tm (A) ≧ Tg (B) + 40 ° C. (Formula 2)
Tg (B)> Tg (A) (Formula 3)
When the melting points and glass transition temperatures of the crystalline resins A and B satisfy the above relational expressions, a fine dispersion of the crystalline resin B is formed in the crystalline resin A during extrusion, and the film is stretched. In addition, a moderate void is formed between the interface between the crystalline resin A as the main resin and the crystalline resin B dispersed therein, and a translucent stretched film having a desired total light transmittance is obtained. .

The melting point Tm (A) and glass transition temperature Tg (A) of the crystalline resin A and the melting point Tm (B) and glass transition temperature Tg (B) of the crystalline resin B are the total light transmittance of the resulting film. From the viewpoint of the above, it is preferable to satisfy the following relational expression.
Tm (A) + 120 ° C. ≧ Tm (B) ≧ Tm (A) + 70 ° C.
Tg (B) + 90 ° C. ≧ Tm (A) ≧ Tg (B) + 50 ° C.
Tg (A) + 120 ° C. ≧ Tg (B) ≧ Tg (A) + 60 ° C.

  In the present invention, in order to satisfy the above (Formula 1), (Formula 2) and (Formula 3), a crystalline resin B having a melting point of 200 ° C. or higher is preferably used. When the melting point Tm (B) of the crystalline resin B is 200 ° C. or more, it becomes easy to control the size of the fine dispersion of the crystalline resin B in the crystalline resin A during melt extrusion. . Moreover, since it becomes easy to make film temperature at the time of film extending | stretching less than Tm (B) and a deformation | transformation of crystalline resin B is moderately suppressed, the total light transmittance of the stretched film obtained falls, desired A stretched film having translucency is easily obtained. Therefore, the present invention also provides a translucent stretched film containing at least crystalline resin A and crystalline resin B having a melting point of 200 ° C. or more and having a total light transmittance of 35 to 85%. The melting point Tm (B) of the crystalline resin B is more preferably 230 ° C. to 280 ° C., and further preferably 240 ° C. to 260 ° C.

  The melting point Tm (A) of the crystalline resin A is preferably 135 ° C. to 175 ° C., more preferably 138 ° C. to 170 ° C., further preferably 140 ° C. to 166 ° C., and particularly preferably 145 ° C. to 164 ° C. Most preferably, it is 150 to 163 degreeC. When the melting point Tm (A) of the crystalline resin A is within the above range, the stretched film productivity and the heat resistance of the obtained stretched film are improved, and the fine dispersion of the crystalline resin B in the crystalline resin A Since it becomes easy to control the magnitude | size of this, it is preferable.

  The glass transition temperature Tg (A) of the crystalline resin A is preferably 50 ° C. or lower, and more preferably −30 to 30 ° C. Moreover, 60-130 degreeC is preferable, as for the glass transition temperature Tg (B) of crystalline resin B, 70-120 degreeC is more preferable, and 80-110 degreeC is further more preferable. When the glass transition temperature Tg (A) of the crystalline resin A and the glass transition temperature Tg (B) of the crystalline resin B are within the above ranges, the crystalline resin A and the crystalline resin B It is preferable because an appropriate gap can be formed between the interfaces. Moreover, since the productivity of a stretched film, the heat resistance of the stretched film obtained, a softness | flexibility, low temperature brittleness, etc. become favorable, it is preferable.

Examples of the crystalline resin A include crystalline polyolefin resins, crystalline polyester resins, crystalline polyamide resins, crystalline polystyrene resins, crystalline acetal resins, and the like.
Among these, a crystalline polyolefin resin is preferable, a crystalline polyolefin resin showing a melting point and a glass transition temperature of the above-described crystalline resin A is excellent in stretchability, and a film stretching temperature of the crystalline resin B described later is used. This is preferable because it becomes moderate in relation to the glass transition temperature and the melting point, and a translucent film showing a desired total light transmittance is easily obtained. As the crystalline polyolefin resin, a homopolymer obtained by polymerizing ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like Or a copolymer etc. are mentioned, These can be used individually or as a 2 or more types of mixture.

Among these, crystalline polypropylene resins, particularly propylene homopolymers and copolymers of propylene and ethylene are preferred. If a homopolymer of propylene is used for the crystalline resin A, the mechanical strength and heat resistance of the film tend to be improved, and if a copolymer of propylene and ethylene is used, the cracking property at low temperature is improved. There is a tendency to reduce the surface glossiness.
Therefore, the crystalline resin A can be used only with a homopolymer of propylene, used in a mixture with a copolymer of propylene and ethylene and / or other polymers, or a copolymer of propylene and ethylene. In addition, it is preferable to use only other polymers, or in the case of a multilayer structure, the required quality can be obtained by using different layers.

  The propylene homopolymer is preferably a crystalline isotactic polypropylene resin. In the present invention, the crystalline isotactic polypropylene resin preferably has a mesopentad fraction ([mmmm]), which is a stereoregularity obtained by high temperature nuclear magnetic resonance (NMR) measurement, of 92% to 98%. More preferably, it is 93% to 97%. When the mesopentad fraction [mmmm] is 92% or more, the crystallinity of the resin is improved by the high stereoregularity component, and high thermal stability and mechanical strength are obtained. On the other hand, when the mesopentad fraction [mmmm] is 98% or less, the stretchability is improved.

The high temperature NMR apparatus for measuring the mesopentad fraction ([mmmm]) is not particularly limited, and is generally a commercially available high temperature nuclear magnetic resonance (NMR) apparatus capable of measuring the degree of stereoregularity of polyolefins. For example, a high temperature Fourier transform nuclear magnetic resonance apparatus (high temperature FT-NMR) JNM-ECP500 manufactured by JEOL Ltd. can be used. The observation nucleus is ¹³ C (125 MHz), the measurement temperature is 135 ° C., and the solvent is ortho-dichlorobenzene (ODCB: ODCB and deuterated ODCB mixed solvent (volume mixing ratio = 4/1)). Used. The method by high temperature NMR can be performed by a known method, for example, the method described in “Japan Analytical Chemistry / Polymer Analysis Research Roundtable, New Edition Polymer Analysis Handbook, Kinokuniya, 1995, p. 610”. . The measurement mode is single pulse proton broadband decoupling, the pulse width is 9.1 μsec (45 ° pulse), the pulse interval is 5.5 sec, the number of integration is 4500 times, and the shift reference is CH ₃ (mmmm) = 21.7 ppm. The

  The pentad fraction representing the degree of stereoregularity is a combination of a pentad of a consensus “meso (m)” arranged in the same direction and a consensus “rasemo (r)” arranged in the same direction (mmmm or mrrm). Etc.) is calculated as a percentage from the integrated intensity value of each signal derived from. Regarding the attribution of each signal derived from mmmm, mrrm, etc., reference is made to the description of the spectrum such as “T. Hayashi et al., Polymer, 29, 138 (1988)”. The mesopentad fraction ([mmmm]) can be controlled by appropriately adjusting the polymerization conditions of the polypropylene resin, the type of catalyst, the amount of catalyst, and the like.

  As a homopolymer of propylene, a known method, for example, a method of polymerizing propylene in a hydrocarbon solvent using a Ziegler catalyst system composed of titanium and an aluminum compound, a method of polymerizing in liquid propylene (bulk polymerization), and a gas phase What was manufactured by the method of superposing | polymerizing etc. may be used and what is marketed may be used. For example, a homopolymer of Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., a homopolymer of Novatec (registered trademark) series manufactured by Japan Polypro Corporation, such as PC412A manufactured by Sun Allomer Co., Ltd. Among these, the Daploy series manufactured by Borealis, the 5014L series manufactured by Korea Oil Chemical Co., Ltd., and the Sumitomo Nobrene (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd. are homopolymers.

  As the copolymer of propylene and ethylene, both a random copolymer of propylene and ethylene and a block copolymer of propylene and ethylene are preferably used, and the copolymer contains 50% by weight or less of ethylene. Those are more preferred. Representative commercial products include, for example, copolymers of Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., copolymers of Novatec (trademark) series manufactured by Nippon Polypro Co., Ltd., and WinTech. Among the (Registered Trademark) series, Sumitomo Chemical Co., Ltd. Sumitomo Noblen (Registered Trademark) series, and the like can be mentioned.

  The crystalline resin A has a melt flow rate measured at 230 ° C. and 21.18 N in accordance with JIS-K7210, preferably 0.5 g / 10 min to 8 g / 10 min, more preferably 1 g / 10 min to 6 g / 10 minutes. By setting the melt flow rate within the above range, the fluidity of the resin becomes an appropriate range, and the thickness of the stretched film can be produced with high accuracy. Moreover, it becomes easy to control the size of the fine dispersion of the crystalline resin B in the crystalline resin A, and a desired total light transmittance is easily obtained.

Examples of the crystalline resin B include a crystalline polycarbonate resin, a crystalline polyester resin, a crystalline polyamide resin, a crystalline polystyrene resin, a polyphenylene sulfide resin, and a polymethylpentene resin. Among these, the dispersibility in the crystalline resin A is moderate, it is easy to control the desired total light transmittance, and it is excellent in resistance to water, acid, alkali, salt, etc., so it is also used for food packaging applications. Since it is easy, crystalline polyester resin, polymethylpentene resin, and crystalline polystyrene resin are preferable.
In particular, it is preferable to use a crystalline polystyrene-based resin because a suitable total light transmittance can be obtained, and pencil writing property and hand cutting property described later can be imparted. The reason is not necessarily clear, but the crystalline polystyrene resin is generally a resin having a preferable melting point and glass transition temperature as described above. It is presumed that the volume occupied in the resin A becomes moderately large, and preferable total light transmittance, pencil writing property and hand cutting property are easily obtained.

  As the crystalline resin B, these resins may be used alone, or two or more kinds of crystalline resins B may be used in combination. By using two or more kinds of crystalline resins B in combination, the size of the fine dispersion of the crystalline resin B in the crystalline resin A and the voids generated between the interfaces of the crystalline resin A and the crystalline resin B Variations in the size of the paper are likely to occur, and a non-uniform appearance such as paper texture is easily obtained, which is preferable.

Examples of the crystalline polycarbonate resin, conforming to JIS-K7210, 300 ° C., the melt volume flow rate measured at 11.77N is a 20 to 50 cm ^3/10 min, mixing and dispersion of the crystalline resin A It is excellent in that it is easy to obtain translucency within the range of desired total light transmittance.

  As the crystalline polyamide-based resin, when so-called nylon 66 synthesized by polycondensation reaction of hexamethylenediamine and adipic acid is used, the melting point becomes appropriate, and the translucency within the desired total light transmittance range is obtained. Since it is obtained, it is preferable.

  The polyphenylene sulfide resin has a specific gravity measured in accordance with ASTM-D792 of 1.4 or less and a tensile modulus measured in accordance with ASTM-D638 of 3.5 GPa or less. The translucency within the transmittance range is preferable because it is easy to obtain.

The polymethylpentene resin has a tensile elastic modulus measured at 23 ° C. according to ASTM-D638 of 1.8 GPa or higher, and a Vicat softening temperature measured according to ASTM-D1525 of 165 ° C. or higher, preferably 170. It is preferable to use a material having a temperature equal to or higher than ° C. because it is easy to obtain translucency within the range of the desired total light transmittance.
Examples of typical commercial products of polymethylpentene resin include TPX (registered trademark) DX845, DX231, DX820, RT18, RT31 and the like manufactured by Mitsui Chemicals.

  As the crystalline polyester-based resin, among the copolymer components, an acid component having terephthalic acid as a main component and a diol component having ethylene glycol as a main component are preferable. The main components terephthalic acid and ethylene glycol are respectively contained in the acid component and the diol component in a proportion of 51 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more. In addition, the crystalline polyester resin may contain 49 mol% or less, preferably 30 mol% or less, and more preferably 20 mol% or less of other copolymer components in the acid component and / or diol component.

  Examples of other copolymerizable acid components include isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4-stilbene dicarboxylic acid, and 4,4-biphenyl. Dicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4 -Aromatic dicarboxylic acid components derived from diphenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, ethylene-bis-p-benzoic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,3 -Induced from cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. It includes aliphatic dicarboxylic acid component is. Of these, aromatic dicarboxylic acid components such as isophthalic acid and 2,6-naphthalenedicarboxylic acid are preferred.

  Examples of the other copolymerizable diol components include diethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, trans-tetramethyl- 1,3-cyclobutanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, decamethylene glycol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, spiroglycol, p-xylenediol, bisphenol A, tetrabromobisphenol A, Tetrabromobisphenol A-bi Diol component derived from (2-hydroxyethyl ether) and the like. Of these, diethylene glycol and 1,3-propanediol are preferred.

  These crystalline polyester resins may be used alone or in combination of two or more. Examples of commercially available crystalline polyester resins include Novapex (registered trademark) series manufactured by Mitsubishi Chemical Corporation and TR-8550FF manufactured by Teijin Limited.

  As the crystalline polystyrene resin, it is preferable to use a styrene resin mainly having a syndiotactic structure. In the present invention, the syndiotactic structure is a syndiotactic structure, that is, phenyl groups and substituted phenyl groups that are side chains with respect to the main chain formed from carbon-carbon bonds are alternately reversed. It has a three-dimensional structure.

The tacticity of the crystalline polystyrene resin can be quantified by a nuclear magnetic resonance method ( ¹³ C-NMR method) using isotope carbon. ^The tacticity measured by the ¹³ C-NMR method can be represented by the abundance ratio of a plurality of consecutive structural units, for example, a dyad for two, a triad for three, a pentad for five. . The polystyrene resin B used in the present invention is usually 75% or more, preferably 85% or more, or racemic triad, preferably 75% or more, preferably 75% or more, or 30% or more, preferably 50%, racemic pentad. It is a styrenic polymer having a syndiotacticity of at least%.

  The types of crystalline polystyrene resins include polystyrene, poly (alkyl styrene), poly (halogenated styrene), poly (halogenated alkyl styrene), poly (alkoxy styrene), poly (vinyl benzoate), and hydrogen of these. And polymer containing these as a main component.

  Poly (alkyl styrene) includes poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene), poly (phenyl styrene), poly (vinyl naphthalene), poly (vinyl styrene) ) And the like. Examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene), and the like. Examples of poly (halogenated alkylstyrene) include poly (chloromethylstyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

  As the comonomer component of the copolymer containing these structural units, in addition to the styrene polymer monomer, olefin monomers such as ethylene, propylene, butene, hexene, and octene, diene monomers such as butadiene and isoprene, and cyclic olefin monomers And polar vinyl monomers such as cyclic diene monomer, methyl methacrylate, maleic anhydride, and acrylonitrile. Preferred styrenic polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tertiarybutylstyrene), poly (p-chlorostyrene), poly (m-chlorostyrene). ), Poly (p-fluorostyrene), hydrogenated polystyrene, and copolymers containing these structural units.

  The crystalline polystyrene resin is preferably a resin obtained by copolymerizing at least styrene and p-methylstyrene as a styrene monomer, and the content of p-methylstyrene in the styrene monomer is 1 to 30 mol%. It is preferable that it is 3 to 15 mol%. By setting it as the said range, it becomes easy to control the magnitude | size of the fine dispersion of a polystyrene-type resin in the crystalline resin A. FIG. Therefore, the total light transmittance can be lowered to a desired range, and the hand cutting ability described later can be obtained. Furthermore, the flexibility of the film is also favorable, and the stretchability is improved, so that breakage and the like are less likely to occur.

  The molecular weight of the crystalline polystyrene resin used in the present invention is not particularly limited, but the weight average molecular weight is preferably 10,000 or more, more preferably 50,000 or more. By setting the weight average molecular weight to 10,000 or more, the thermal properties and mechanical strength of the obtained stretched film can be improved. Moreover, the upper limit of the molecular weight of the polystyrene resin used in the present invention is preferably 3 million or less, more preferably 1.5 million or less, from the viewpoint of mixing and dispersibility with the crystalline resin A.

  The crystalline polystyrene resin has a melt flow rate measured at 300 ° C. and 11.77 N in accordance with JIS-K7210, preferably 1 to 40 g / 10 minutes, and more preferably 10 to 35 g / 10 minutes. By controlling the melt flow rate within the above range, the size of the fine dispersion of the crystalline resin B in the crystalline resin A can be easily controlled. Therefore, it becomes easy to obtain a desired total light transmittance.

  In the present invention, the crystalline polystyrene resin may be one produced by a known method, for example, a method using styrene as a monomer and polymerizing using a metallocene catalyst, or a commercially available one. . Representative commercial products include, for example, XAREC (registered trademark) 142ZE, XAREC (registered trademark) 300ZC, XAREC (registered trademark) 130ZC, and XAREC (registered trademark) 90ZC manufactured by Idemitsu Kosan Co., Ltd., and the like. These crystalline polystyrene resins may be used alone or in combination of two or more.

  The crystalline resin A can be preferably used in an amount of 55 to 85% by mass, more preferably 58 to 79% by mass, and still more preferably 62 to 75% by mass based on the total mass of the resin component. By using the crystalline resin A in the above range, a film excellent in stretchability and mechanical strength can be easily obtained. The crystalline resin B can be preferably used in an amount of 15 to 45% by mass, more preferably 21 to 42% by mass, and further preferably 25 to 38% by mass based on the total mass of the resin components. By setting the crystalline resin B to 15% by mass or more based on the total mass of the resin component, the total light transmittance is lowered to be within a desired range, and the later-described hand cutting property and pencil writing property are improved. be able to. Further, by setting the crystalline resin B to 45% by mass or less based on the total mass of the resin component, the total light transmittance is within a desired range without making it too low, and the stretchability is improved and the fracture is improved. Generation | occurrence | production etc. can be suppressed.

  The translucent stretched film of the present invention includes a crystalline resin having a melting point and a glass transition temperature different from the crystalline resin A and the crystalline resin B as a resin component in addition to the crystalline resin A and the crystalline resin B. Or adjust amorphous resin (hereinafter also referred to as "other resin") by adjusting stretchability, adjusting low temperature impact resistance, adjusting surface roughness, adjusting various physical properties such as stiffness, strength, and elongation. You may make it contain in the range which does not impair the effect of this invention for the objective.

  Other resins are not particularly limited, and conventionally known resins that are suitable for stretched film applications can be used as appropriate in the present invention. Examples of other resins include polyolefin resins such as polyethylene, polypropylene, poly (1-butene), polyisobutene, poly (1-pentene), poly (4-methyl-1-pentene), and copolymers thereof. Examples of the resin include copolymers of α-olefins such as ethylene-propylene copolymer, propylene-butene copolymer, and ethylene-butene copolymer. Further, styrene resins, vinyl resins, polyester resins, polyurethane resins, nylon resins and copolymers thereof, for example, vinyl monomers-diene monomer copolymers such as styrene-butadiene copolymers. And vinyl monomer-diene monomer-vinyl monomer copolymer such as styrene-butadiene-styrene copolymer.

  The content of such other resins is preferably 15% by mass or less, more preferably 10% by mass or less, based on the total mass of the resin components.

  If necessary, the translucent stretched film of the present invention may contain additives such as heat stabilizers, antioxidants, organic and inorganic lubricants, chlorine capture agents, antistatic agents and the like as optional components. Good.

  Examples of heat stabilizers and antioxidants include phenol-based, hindered amine-based, phosphite-based, lactone-based, and tocopherol-based heat stabilizers and antioxidants. More specifically, dibutylhydroxytoluene, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (“Irganox (registered trademark) 1010” manufactured by BASF Japan Ltd.), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4hydroxy) benzene (“Irganox (registered trademark) 1330” manufactured by BASF Japan Ltd.), tris (2, 4-di-t-butylphenyl) phosphite ("Irgafos (registered trademark) 168" manufactured by BASF Japan Ltd.) and the like. Among these, at least one selected from phenolic antioxidants or a combination thereof, a combination of phenolic and phosphite, and phenolic and lactone, phenolic, phosphite and lactone A combination is preferable from the viewpoint of imparting chemical stability of the film.

  Examples of lubricants include organic lubricants such as stearamide, erucamide, and other aliphatic amides, lauric acid diethanolamide, alkyldiethanolamine, aliphatic monoglycerides, aliphatic diglycerides, silicone cross-linked polymers, and inorganic lubricants such as silica. , Alumina and the like are mentioned, but organic lubricants with less stain on the printing plate for printing applications are preferred.

  Examples of the chlorine scavenger include calcium stearate, metal soaps, hydrotalcite and the like.

Examples of the antistatic agent include alkylmethyl dibetaine, alkylamine diethanol and / or alkylamine ethanol ester and / or alkylamine diethanol diester. Of these, two or more kinds of antistatic agents may be used in combination, and an aliphatic alcohol may be used in combination.
Among these, it is preferable to use stearyl diethanolamine monostearate and stearyl diethanolamine in combination because of excellent antistatic performance and improved printability.
As a typical example of a commercially available antistatic agent, there is an electro stripper series manufactured by Kao Corporation.

  The translucent stretched film of the present invention can be produced using a conventionally known method. For example, first, the crystalline resin A and the crystalline resin B can be produced by blending with other resins and / or additives as necessary, and then extruding and biaxially stretching.

  As a method of blending the crystalline resin A and the crystalline resin B, for example, pellets or powders of the crystalline resin A and the crystalline resin B, and other resin pellets, powders, and / or additions as necessary. There is a dry blending method using a batch mixing device such as a tumbler or a mixer, or a continuous metering mixing device together with the agent. In addition, pellets and powders of crystalline resin A and crystalline resin B are supplied to a kneader together with pellets, powders and / or additives of other resins as necessary, and melt blended by melt blending resin. Examples thereof include a method for obtaining a composition.

  In the present invention, by melt kneading, the mixing / dispersibility of the crystalline resin A and the crystalline resin B is excellent, and the size of the fine dispersion of the crystalline resin B in the crystalline resin A can be easily controlled. Thus, the total light transmittance can be lowered to a desired range, which is preferable. A known kneading machine can be used as a kneading machine for melt kneading, and a single screw type, a twin screw type, or a multi-screw type higher than that may be used. Any of the kneading types rotating in the same direction or rotating in the opposite direction may be used, but a twin screw type kneading machine rotating in the same direction is preferable because the size of the fine dispersion can be easily controlled.

  The kneading temperature for melt kneading is preferably in the range of Tm (B) to Tm (B) + 50 ° C., more preferably Tm (B) + 5 ° C. to Tm (B) + 30 ° C. The above temperature range is preferable because the size of the fine dispersion of the crystalline resin B in the crystalline resin A can be controlled and a desired total light transmittance can be obtained. An inert gas such as nitrogen may be purged in order to prevent deterioration of the resin during melt kneading.

  The melt-kneaded resin can be pelletized to an appropriate size using a generally known granulator to obtain melt blend resin composition pellets.

  As a stretching method for obtaining the translucent stretched film of the present invention, known methods such as a method of stretching between rolls having a difference in peripheral speed, a tenter method, a tubular method, and the like can be used. As the stretching direction, uniaxial stretching, biaxial stretching, biaxial stretching in an oblique direction, and the like can be performed. For biaxial or more stretching, both sequential stretching and simultaneous stretching are applicable. Among these, since a film having a uniform total light transmittance can be easily obtained, a simultaneous biaxial stretching method by a tenter method, a sequential biaxial stretching method by a tenter method, and a longitudinal (flow, MD) A sequential biaxial stretching method in which a transverse (width, TD) stretching is performed by a tenter method after stretching is preferable.

Stretching is usually performed so that the film temperature (Ts) is a temperature between Tm (A) and Tg (A) of the crystalline resin A which is the main resin. Here, when Ts is a temperature close to or lower than Tg (B), the crystalline resin B cannot be sufficiently deformed during stretching, and a large void is formed between the interfaces of the crystalline resin A and the crystalline resin B. Thus, it may become opaque and a translucent stretched film satisfying the desired total light transmittance may not be obtained. Further, when Ts is a temperature close to or higher than Tm (B), the crystalline resin B easily follows the deformation of the crystalline resin A during stretching to become a transparent film, and the total light transmittance tends to increase. In some cases, a translucent stretched film that satisfies the desired total light transmittance may not be obtained. Therefore, in the present invention, when Ts is lower than Tm (A) and higher than Tg (B), the following relational expression:
Tm (B)> Tm (A)>Ts> Tg (B)> Tg (A)
Is satisfied, and a translucent stretched film is obtained, which is preferable. Here, the film temperature Ts is the temperature of the film at the time when the film starts to be stretched, but when the film temperature at each stage is different in multistage stretching such as sequential biaxial stretching, the lowest film temperature among them is set. Let Ts.

  Ts is more preferable when it is 10 ° C higher than Tg (B), and more preferably when it is higher by 20 ° C to 70 ° C than Tg (B). In this case, the crystalline resin B at the time of stretching tends to be appropriately deformed and the total light transmittance tends to be high, and a translucent film exhibiting a desired total light transmittance is easily obtained. Further, when Ts is 80 ° C. to 130 ° C. lower than Tm (B), the deformation of the crystalline resin B is moderately suppressed at the time of stretching, so that the total light transmittance tends to be low, and desired total light transmission is achieved. This is preferable because a translucent film exhibiting the rate is easily obtained.

  Hereinafter, although the method to obtain the translucent stretched film of this invention by a sequential biaxial stretching method is demonstrated, it is not limited to this.

  After the dry blend product and / or melt blend resin composition pellets of crystalline resin A and crystalline resin B obtained as described above are supplied to an extruder, heated and melted, and fine foreign matters and the like are removed by a filter or the like , And melt extruded into a sheet from a T-die.

  There is no restriction on the screw type of the extruder, and a single screw type, a twin screw type, or a multi-screw type higher than that may be used. However, when the resin mixing method is dry blending, a twin screw type When the multi-screw type is used, it is excellent in mixing and dispersibility.

  The extrusion temperature is preferably in the range of Tm (B) to Tm (B) + 50 ° C, more preferably Tm (B) + 5 ° C to Tm (B) + 30 ° C. An inert gas such as nitrogen may be purged to prevent thermal degradation of the resin during extrusion.

  The melt-extruded resin sheet is formed into a sheet shape by a known method such as an air knife, another roll, or static adhesion on at least one metal drum set to a temperature of 25 to 120 ° C. And becomes a raw sheet. When the temperature of the metal drum is within the above range, crystal growth of the crystalline resin B can be controlled, deformation during stretching is suppressed, and a desired total light transmittance is easily obtained. A more preferable temperature of the metal drum is 30 to 70 ° C.

  The translucent stretched film of the present invention may be a stretched film obtained by extruding a dry blend and / or melt blend resin composition from a single-layer die, and is intended to obtain a desired film thickness. In addition, a film obtained by laminating a plurality of layers and / or films using a conventionally known laminating method such as a co-extrusion method, a laminating method, a heat sealing method or the like may be used.

  Co-extrusion methods include die pre-lamination method in which molten resin is brought into contact with the feed block in front of the die, die-in-die lamination method in which the molten resin is brought into contact with the path inside the die, and die outer lamination in which discharge is made from multiple concentric lips. Law. For example, in the case of the in-die lamination method, a layer b / layer a / layer b composed of a surface layer (skin layer: layer b) and a core layer (layer a) is used by using a multilayer die such as a three-layer multi-manifold die. It can be a three-layer structure.

  Examples of the laminating method include an extrusion laminating method using a melt extrusion molding equipment used in the T-die method, and directly molding a laminated resin film by extruding a molten resin film onto another film.

  The heat sealing method includes an external heating method in which a heated metal body is pressed from the outside of the film onto a plurality of bonded films, and the conducted heat melts and bonds the film, and heat is applied to the film by high-frequency radio waves and ultrasonic waves. An internal heat generation method for generating and joining the substrate is used.

  In the present invention, the above laminating methods can be used alone or in combination.

  In the case of laminating, the kind and the addition amount of the crystalline thermoplastic resin B in each layer may be the same or different. If different, it is easy to achieve a desired total light transmittance in a layer with a large amount of crystalline thermoplastic resin B and improve stretchability with a layer with a small amount of addition, etc. . When two or more layers are laminated, at least one layer contains the crystalline thermoplastic resin B in an amount of 15 to 45% by mass based on the total mass of the resin components, and at least one layer contains the crystalline thermoplastic resin B as a resin. It is preferable to contain 0-25 mass% or less based on the total mass of the components.

When the film is used for packaging purposes, a heat seal layer can be laminated on one side and / or both sides of the film as necessary.
Preferably, the translucent stretched film of the present invention has a heat seal layer on at least one side.

The resin used for the heat seal layer is a thermoplastic resin having a melting point of 150 ° C. or less, and is selected from α-olefin monomers having 2 to 10 carbon atoms such as ethylene, propylene, butene, pentene, hexene, octene, and decene. A random copolymer or block copolymer obtained by polymerizing two or more of these is preferred. These copolymers can be used alone or in combination.
Particularly preferred is a crystalline propylene-α-olefin random copolymer, and examples of the α-olefin include ethylene or an α-olefin having 4 to 20 carbon atoms, such as ethylene, butene-1, hexene-1, octene- 1 or the like is preferably used, and a copolymer or terpolymer using ethylene or butylene is particularly preferably used. For example, a propylene-ethylene-butene random copolymer (FL6741G manufactured by Sumitomo Chemical Co., Ltd.) is preferable. You may use together antiblocking agents, such as acrylic resin type microparticles | fine-particles and a silica, in the range which does not impair the effect of this invention in a heat seal layer.

As the sequential biaxial stretching method, it is necessary to adjust the stretching temperature and the stretching ratio depending on the melting point and glass transition temperature of the resin used. First, the raw sheet is preferably 100 to 180 ° C, more preferably 120 to 170 ° C. The temperature is maintained at a temperature of 2 to 10 times, preferably between 2 and 10 times, more preferably 2.5 to 8 times, and even more preferably 3 to 6 times in the longitudinal direction. Stretch to. Subsequently, the stretched film is subjected to a tenter method, preferably at a temperature of 100 to 180 ° C., more preferably 120 to 175 ° C., preferably 2 to 12 times, more preferably 2.5 to 11.5 times in the transverse direction. More preferably, the film is stretched 3 to 11 times, then subjected to relaxation and heat setting and then wound.
The wound film is preferably subjected to an aging treatment in an atmosphere of about 20 to 45 ° C. and then cut to a desired product width. Thus, a stretched film having excellent mechanical strength and rigidity can be obtained. In addition, if the temperature at the time of extending | stretching is raised, the total light transmittance will rise easily and the hand cutting property mentioned later will be easy to improve, and if the temperature is lowered, the total light transmittance tends to be lowered. Moreover, when the draw ratio is high, the hand cutting property in that direction tends to be improved.

The film can be subjected to corona treatment, plasma treatment, flame treatment, etc., as necessary, online or offline. In particular, when this film is used in printing applications, treatments such as corona treatment, plasma treatment, and flame treatment are performed on one and / or both sides of the film for the purpose of improving the wetting and spreading of printing ink and adhesion. It is preferable to carry out. In the present invention, the wetting tension of K6768: 1999 on the film surface is preferably 36 mN / m or more, more preferably 38 to 45 mN / m.
Alternatively, a printability imparting layer having the same wetting tension and further having smoothness may be provided.

  In the translucent stretched film of the present invention, the 60 ° specular glossiness of at least one surface is preferably 5% to 35%, more preferably 8% to 30%, and further preferably 10 to 25%. A 60-degree specular gloss of 5% to 35% is preferable because the texture is paper-like and the visibility of printed characters and patterns is good. In the present invention, the 60-degree specular gloss is a value measured according to JIS-Z8741 (Method 3).

  The translucent stretched film of the present invention prevents problems such as contamination of the package due to the removal of inorganic materials, stains on the printing plate for printing applications, rough cutting surfaces during cutting, and fast cutting blade consumption. Therefore, the ash content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less based on the total mass of the film. The lower limit of ash content is not particularly limited, but it is preferably as small as possible, for example, 0.01% by mass, 0% by mass, and the like. In the present invention, the ash content can be measured according to the JIS-K7250-1 (2006) A method.

  The thickness of the translucent stretched film of the present invention is preferably 10 μm to 150 μm, more preferably 15 to 100 μm, still more preferably 20 to 60 μm, although it depends on the intended use. When the thickness of the film is 10 μm or more, sufficient strength is easily obtained. Moreover, it is excellent in stretchability and productivity as the thickness of a film is 150 micrometers or less.

  The translucent stretched film of the present invention preferably has hand cutting properties. In general, plastic film does not have hand cutting unless it has a special shape such as a cut, whereas translucent paper used for packaging paper for foods and drugs does not have a cut. Both can be torn by hand, and can be opened by hand when used in a packaging bag or the like. Therefore, when the translucent stretched film of the present invention has hand cutting properties, it can also be used for packaging papers such as foods and medicines that require hand cutting properties.

  The translucent stretched film of the present invention preferably has pencil writing properties. In general, a plastic film cannot be written with a pencil or the like because the film surface is too smooth, but in applications such as transcribing paper, pencil writing is required. When the translucent stretched film of the present invention has a pencil writing property, it can be pencil-written like paper even though it does not contain inorganic particles, and can be used for applications such as transcribing paper. Pencil writing property is considered to be an effect of containing a fine dispersion of a crystalline thermoplastic resin.

  The translucent stretched film of the present invention preferably has heat sealability and / or printability. When the translucent stretched film of the present invention has heat sealability and / or printability, it can be preferably used for food packaging applications.

  The translucent stretched film of the present invention is for packaging, food packaging, chemical packaging, decoration, labeling, tape substrate, printing substrate, poster paper, thermal paper substrate, recording paper substrate, etc. Can be suitably used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

[Melt flow rate of resin (MFR)]
According to JIS K-7210 (1999), it measured using the melt indexer by Toyo Seiki Seisakusho. As for the measurement conditions, the crystalline resin A was measured at a measurement temperature of 230 ° C. and a load of 21.18 N, and the crystalline resin B was measured at a measurement temperature of 300 ° C. and a load of 11.77 N.

[Melting point of resin, glass transition temperature]
Calculation was performed by the following procedure using an input compensation DSC and Diamond DSC manufactured by Perkin Elmer. 5 mg of each resin was weighed out, packed in an aluminum sample holder, and set in a DSC apparatus. The temperature was raised from −40 ° C. to 300 ° C. at a rate of 10 ° C./min under a nitrogen flow, held at 300 ° C. for 5 minutes, cooled to −40 ° C. at 10 ° C./min, and held at −40 ° C. for 5 minutes. Thereafter, the melting point and the glass transition temperature were determined from the DSC curve when the temperature was raised again to 300 ° C. at 10 ° C./min. The melting point defined in 9.1- (1) of JIS-K7121 (the maximum melting peak when multiple melting peaks are shown) is the melting point, and the midpoint glass transition temperature defined in 9.3- (1) of JIS-K7121 The glass transition temperature was taken.

[Film thickness]
It measured based on JIS-C2330 using Citizen Seimitsu Co., Ltd. paper thickness measuring device MEI-11.

[Total light transmittance of film]
It measured based on JIS-K7361 using Nippon Denshoku Industries Co., Ltd. haze meter NDH-5000.

[60 degree specular gloss of film]
Using a variable angle gloss meter GM-3D manufactured by Murakami Color Research Laboratory Co., Ltd., the 60-degree specular gloss was measured according to JIS-Z8741 (Method 3). In addition, a measurement is the value which measured about the vertical direction and the horizontal direction of the film, and averaged both.

[Film ash]
According to JIS-K7250-1 (2006) A method, it measured by the measurement sample amount 200g.

[Pencil writing]
Each film was written with an HB pencil, and the writing state was evaluated according to the following criteria.
A: The writing is deep and clear, and the writing property is excellent.
○: Writing is possible at a readable density, and there is no practical problem.
Δ: Written, but thin and practically problematic.
×: Cannot be written.

[Hand cutting]
The tearing condition when the film was torn with the fingertip was evaluated according to the following criteria. In addition, evaluation was evaluated for each of the vertical direction and the horizontal direction of the film.
◎: Easy tearing ○: Some force is required, but tearing is possible and there is no practical problem.
Δ: If the nail is raised and force is not applied, it is not torn and is not practical.
X: The film is tenacious and does not tear.

[Heat sealability evaluation method]
In an environment of 23 ° C. and 50% RH, a heat inclined heat sealer HG-100-2 (Toyo Incorporated) with the heat seal surfaces of two samples cut in the MD direction 250 mm and the TD direction 50 mm overlapped with each other. (Seiki Seisakusho Co., Ltd.) was used, and the heat seal treatment was performed under conditions of a seal temperature of 110 ° C., a seal pressure of 200 KPa, a seal time of 2 seconds, and a heat seal portion width (corresponding to the MD direction of the film) of 1 cm. Next, after the TD direction of the sample adjusted to 23 ° C. was cut to 25 mm, each end of the two films was moved up and down using a tensile tester Technograph TGI-1kN (manufactured by Minebea Co., Ltd.). The sample was sandwiched between chucks and peeled 180 ° at a pulling speed of 300 mm / min, and the maximum value of stress at that time was measured. The average value of the three measurements was taken as the adhesive strength (N / 25 mm) of the heat seal part.
The adhesive strength was evaluated as follows.
(Double-circle): 4N or more and less than 6N: Heat seal intensity | strength is moderate.
○: 6N or more to less than 8N: Heat seal strength is slightly strong, but practical.
○: 3N or more and less than 4N: Heat seal strength is slightly weak, but practical.
(Triangle | delta): 8N or more: Heat seal intensity | strength is strong and there exists difficulty in opening.
X: Less than 3N: Heat seal strength is weak and impractical.

[Printability evaluation method]
Four-color gravure printing was carried out on a gravure rotary printing press (OSG-550HDX manufactured by Orient Sogyo Co., Ltd.) using Ink Ultima NT805 manufactured by DIC Graphics Corporation. For each of the four colors of CMYK, 100%, 90%, 80%, 70%, 60% of 5 gradations are printed, and the printed part (4 colors x 5 gradations of 20 gradations) is visually observed and evaluated as follows. did. ◎: No dot missing on any wrinkles, which is good.
○: There are wrinkles in which dot missing is observed from 1 to 6 mm, but there is no practical problem.
Δ: The wrinkles in which missing dots are observed are 7 mm or less and 12 mm or less, which is not preferable for practical use.
X: There are 13 or more wrinkles with missing dots, which is not practical.

[Example 1]
As crystalline resin A, Prime Polypro (registered trademark) F-300SP (manufactured by Prime Polymer Co., Ltd., crystalline polypropylene homopolymer, MFR = 3 g / 10 min, melting point 160 ° C., glass transition temperature −17 ° C.) and crystalline resin As B, pellets of Zarek (registered trademark) 142ZE (manufactured by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition point 95 ° C.) are each dry blended in a mixer at the ratio shown in Table 1 and mixed. Raw material pellets were prepared.

  The resulting mixed raw material pellets are charged from a hopper to a device in which a twin screw extruder (L / D = 25) equipped with a strand die is connected to a laboratory plast mill (model 4C150) manufactured by Toyo Seiki Seisakusho Co., Ltd. Melt-kneaded at 260 ° C. The mixed resin was extruded into strands, cooled with water, and cut into pellets with a strand cutter to obtain melt blend resin composition pellets.

  Melt blend resin composition pellets are fed from a hopper into a uniaxial screw type extruder a for forming a core layer and a uniaxial screw type extruder b for forming a skin layer, and are melted. It laminated | stacked on the inside of die | dye at the 3 layer structure of bb, and was extruded as a 3 layer laminated resin layer. The ratio of the amount of extruded resin between the single screw type extruder a and the single screw type extruder b was 2: 1. The extruded resin layer was cooled and solidified while being pressed with air pressure on a cooling drum controlled at 45 ° C. using an air knife to obtain a raw sheet.

  The obtained raw sheet was stretched using a batch type biaxial stretching machine KARO manufactured by Bruckner. The stretching method was a sequential biaxial stretching method in which the film was stretched in the longitudinal direction and then stretched in the transverse direction. The film temperature (Ts) was preheated to 135 ° C. in an oven at a set temperature of 150 ° C., and first stretched up to 5 times in the machine direction at a stretching speed of 6 times / second. Next, the film temperature was preheated to 145 ° C. in an oven at a set temperature of 165 ° C., and the film was stretched 10 times in the transverse direction at a stretching speed of 1 / second. Next, in the same oven, the transverse direction was relaxed to 9.5 times at a relaxation rate of 0.5 times / second, then heat-set for 10 seconds, then discharged from the oven, cooled to room temperature, and 30 μm thick A stretched film was obtained.

[Examples 2 to 4]
A stretched film was obtained in the same manner as in Example 1 except that the mixing ratio of the raw material pellets was changed to the number of parts shown in Table 1.

Example 5
The same raw sheet as in Example 1 was stretched by a simultaneous biaxial stretching method in which longitudinal stretching and lateral stretching were simultaneously performed. The film temperature (Ts) was preheated to 145 ° C. in an oven at a set temperature of 165 ° C., and stretched to 7.4 times at a stretching speed of 1 / second in both the machine direction and the transverse direction. Next, in the same oven, both the longitudinal direction and the transverse direction were relaxed to 7 times, and then heat-set for 10 seconds, then discharged from the oven and cooled to room temperature to obtain a stretched film.

Example 6
Wintech (registered trademark) WFW5T (manufactured by Nippon Polypro Co., Ltd., crystalline propylene-ethylene copolymer, MFR = 2.5 g / 10 min, melting point 142 ° C., glass transition temperature −19 ° C.) 65 mass as crystalline resin A Parts, and 35 parts by mass of pellets of Zalek (registered trademark) 142ZE (made by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition point 95 ° C.) as the crystalline resin B, and the stretching temperature, A stretched film in the same manner as in Example 1 except that the film temperature was preheated to 130 ° C in an oven at a set temperature of 145 ° C in the machine direction and the film temperature was preheated to 135 ° C in an oven at a set temperature of 150 ° C in the transverse direction. Got.

Example 7
Example 1 except that Novapex (registered trademark) BK2180 (manufactured by Mitsubishi Chemical Corporation, crystalline polyester resin, melting point 250 ° C., glass transition temperature 77 ° C.) was used as the crystalline resin B in the number of parts shown in Table 1. Thus, a stretched film was obtained.

Example 8
Example 1 except that Novapex (registered trademark) GS900 (manufactured by Mitsubishi Chemical Corporation, crystalline polyester resin, melting point 255 ° C., glass transition temperature 82 ° C.) was used as the crystalline resin B in the number of parts shown in Table 1. Thus, a stretched film was obtained.

Example 9
As crystalline resin A, Prime Polypro (registered trademark) F-300SP (manufactured by Prime Polymer Co., Ltd., crystalline polypropylene homopolymer, MFR = 3 g / 10 min, melting point 160 ° C., glass transition temperature −17 ° C.) 65 parts by mass, As a crystalline resin B, 35 parts by mass of Zarek (registered trademark) 142ZE (made by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition point 95 ° C.) is dry-blended with a mixer to prepare a mixed raw material (1 ) Was prepared.
As the crystalline resin A, Prime Polypro (registered trademark) F-300SP (manufactured by Prime Polymer Co., Ltd., crystalline polypropylene homopolymer, MFR = 3 g / 10 min, melting point 160 ° C., glass transition temperature −17 ° C.) 79.7 mass Parts, 15 parts by mass of Zarek (registered trademark) 142ZE (made by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition point 95 ° C.) as crystalline resin B, and TPX (registered trademark) as crystalline resin B DX-845 (manufactured by Mitsui Chemicals, polymethylpentene resin, melting point 232 ° C., glass transition point 23 ° C., tensile modulus 1.9 GPa, Vicat softening temperature 168 ° C.) 5 parts by mass, and antistatic agent electrostripper TS -15B (stearyl diethanolamine monostearate, stearyl diethanolamine Fine aliphatic mixtures of alcohols were prepared mixture was dry-blended raw material (2) at Kao Corporation) 0.3 parts by mass of the mixer.
The mixed raw material (1) obtained was introduced from a hopper into a device in which a twin-screw extruder (L / D = 25) equipped with a strand die was connected to a laboratory plastic mill (model 4C150) manufactured by Toyo Seiki Seisakusho Co., Ltd. Melt kneading was performed at a set temperature of 260 ° C. The mixed resin was extruded into strands, cooled with water, and cut into pellets with a strand cutter to obtain melt blend resin composition pellets (1). Subsequently, melt blend resin composition pellets (2) were obtained in the same manner using the mixed raw material (2).
Melt blend resin composition pellets (1) into a single screw type extruder b for forming a layer b, melt blend resin composition pellets (2) into a single screw type extruder a for forming a layer, Each was injected from a hopper and melted, and these were laminated in a three-layer configuration of bb inside a three-layer multi-manifold die and extruded as a three-layer laminated resin layer. The ratio of the amount of extruded resin between the single screw type extruder a and the single screw type extruder b was 2: 1. The extruded resin layer was cooled and solidified while being pressed with air pressure on a cooling drum controlled at 45 ° C. using an air knife to obtain a raw sheet.
The stretched film was obtained like Example 1 with respect to the obtained raw fabric sheet. Corona treatment was performed on both sides of the obtained stretched film. The strength of the corona treatment was adjusted so that the wetting tension of the treated surface one day after the treatment was 40 mN / m.

Example 10
As resin for heat seal layer, 90 parts by mass of propylene-ethylene-butene random copolymer (FL6741G manufactured by Sumitomo Chemical Co., Ltd.) and 10 parts by mass of propylene-butene copolymer (Tafmer MX7070 manufactured by Mitsui Chemicals, Inc.), blocking prevention 0.2 parts by mass of amorphous silica (Silicia 730 manufactured by Fuji Silysia Chemical Co., Ltd.) was dry blended with a mixer as an agent to prepare a mixed raw material (3).
Melt blend resin composition pellets (1) similar to those in Example 9 are applied to a single screw type extruder b for forming layer b, and melt blend resin composition pellets (2) similar to those in Example 9 are layered to a layers. The mixed raw material (3) is fed into the single screw type extruder HS for forming the HS layer into the single screw type extruder a for forming from the hopper and melted. Were laminated in a three-layer configuration of ba-HS and extruded as a three-layer laminated resin layer. The ratio of the extrusion resin amount of the single screw type extruder b, the single screw type extruder a, and the single screw type extruder HS was 1: 4: 1. The HS layer side of the extruded resin layer was cooled and solidified while being pressed with air pressure on a cooling drum controlled at 45 ° C. using an air knife to obtain an original fabric sheet.
The stretched film was obtained like Example 1 with respect to the obtained raw fabric sheet. Corona treatment was performed on the b layer side of the obtained stretched film. The strength of the corona treatment was adjusted so that the wetting tension of the treated surface one day after the treatment was 40 mN / m.

[Comparative Example 1]
A stretched film was obtained in the same manner as in Example 1 except that Prime Polypro (registered trademark) F-300SP was used alone without performing dry blending and melt mixing.

[Comparative Example 2]
Zalec® 142ZE was used alone without dry blending and melt mixing. The pellets are put into a uniaxial screw type extruder a for forming a core layer and a uniaxial screw type extruder b for forming a skin layer from a hopper and melted, and these are melted in a three-layer multi-manifold die. Were laminated in a three-layer configuration of b-a-b and extruded as a three-layer laminated resin layer. The ratio of the amount of extruded resin between the single screw type extruder a and the single screw type extruder b was 2: 1.
The extruded resin layer was cooled and solidified while being pressed on a cooling drum controlled at 80 ° C. with air pressure using an air knife, to obtain an original fabric sheet.
The obtained raw sheet was stretched using a batch type biaxial stretching machine KARO manufactured by Bruckner. The stretching method was carried out by a simultaneous biaxial stretching method in which longitudinal stretching and lateral stretching were simultaneously performed. The film temperature (Ts) was preheated to 110 ° C. in an oven at a set temperature of 130 ° C., and stretched up to 3 times at a stretching speed of 1 / second in both the machine direction and the transverse direction. Next, after heat setting in an oven at a set temperature of 200 ° C. for 20 seconds, the film was discharged from the oven and cooled to room temperature to obtain a stretched film.

[Comparative Example 3]
The mixing ratio of the raw material pellets was changed to the number of parts shown in Table 1, and the film temperature (Ts) was preheated to 90 ° C. in an oven at a set temperature of 100 ° C. in the machine direction in the machine direction, and the draw ratio was made in the transverse direction. A stretched film was obtained in the same manner as in Example 1 except that the ratio was changed to 8 times.

[Comparative Example 4]
Cyclic olefin resin (Apel (registered trademark) APL6015, Mitsui Chemicals, Inc., glass transition temperature 145) that does not use crystalline resin B and is amorphous instead and does not show a clear melting peak (melting point) in the DSC curve. A stretched film was obtained in the same manner as in Example 1 except that [° C.] was used.

[Comparative Example 5]
Instead of using crystalline resin B, dry-blend light calcium carbonate powder (Caltex 5, manufactured by Maruo Calcium Co., Ltd., average particle size 0.9 μm), which is inorganic particles, in the number of parts shown in Table 1 to prepare a mixed raw material did.
The molten raw material is introduced into a single screw extruder a for forming the core layer and a single screw extruder b for forming the skin layer from the hopper and melted. A sheet was obtained.
A stretched film was prepared in the same manner as in Example 1 except that the film temperature (Ts) was preheated to 110 ° C. in an oven having a set temperature of 125 ° C. in the machine direction with respect to the obtained raw sheet. Obtained.

  The measurement and evaluation result of the obtained stretched film in each Example are shown with the composition of the resin used for each stretched film.

As shown in Table 1, the stretched films obtained in Examples 1 to 8 were translucent stretched films having a total light transmittance of 35 to 85% and low gloss. Further, these films have pencil writing properties even without an inorganic pigment, and have good hand cutting properties in at least one of the stretching directions. Therefore, the translucent film of the present invention is a film having excellent moisture resistance, water resistance, oil resistance and mechanical strength compared to paper, but has a paper-like appearance due to moderate translucency and low gloss. Furthermore, it is understood that it can be used as a substitute for paper because it has pencil writing ability and hand cutting ability.
Moreover, since the stretched film obtained in Examples 9-10 is a translucent stretched film with a total light transmittance of between 35-85% and low glossiness, it shows a paper-like appearance. In addition, it is excellent in printability and can be suitably used for packaging bags having a high-class feeling such as Japanese paper.
In addition, the stretched film obtained in Example 10 has heat sealability and can be suitably used for packaging forms that require heat sealability of foods such as bread.

  On the other hand, in Comparative Examples 1 and 2 using a crystalline resin alone, only a highly transparent film having neither pencil handwriting nor hand cutting ability was obtained. In Comparative Example 3 in which the amount of the crystalline resin B was too small and the film temperature during stretching was low, the transparency was low, and neither the pencil writing property nor the hand cutting property was present. Furthermore, the film obtained in Comparative Example 4 using an amorphous cyclic olefin resin not according to the present invention as the crystalline resin B is not sufficiently transparent, and in Comparative Example 5 using light calcium carbonate powder. Transparency could not be obtained even with a small amount of light calcium carbonate powder.

Claims (10)

It contains at least crystalline thermoplastic resin A and crystalline thermoplastic resin B as resin components, and has melting point Tm (A) and glass transition temperature Tg (A) of crystalline thermoplastic resin A, crystalline thermoplastic resin B A translucent stretched film having a total light transmittance of 35 to 85%, wherein the melting point Tm (B) and the glass transition temperature Tg (B) satisfy the following formula simultaneously.
Tm (B) ≧ Tm (A) + 50 ° C.
Tm (A) ≧ Tg (B) + 40 ° C.
Tg (B)> Tg (A)   The translucent stretched film according to claim 1, comprising 15 to 45% by mass of the crystalline thermoplastic resin B based on the total mass of the resin components.   The translucent stretched film according to claim 1 or 2, wherein the ash content is 1% by mass or less based on the total mass of the film.   The translucent stretched film according to any one of claims 1 to 3, wherein the 60-degree specular gloss is 5 to 35%.   The translucent stretched film according to any one of claims 1 to 4, wherein Tm (A) is 135 ° C to 175 ° C.   The translucent stretched film according to any one of claims 1 to 5, wherein Tm (B) is 200 ° C or higher.   The translucent stretched film according to any one of claims 1 to 6, wherein Tg (B) is 60 to 130 ° C.   The translucent stretched film according to any one of claims 1 to 7, wherein the crystalline thermoplastic resin A is a crystalline polyolefin resin.   The translucent stretched film according to any one of claims 1 to 8, which has a heat seal layer on at least one side.   The translucent stretched film according to any one of claims 1 to 9, wherein the wetting tension of at least one surface is 36 to 45 mN / m.