JP2672353B2 - Labeled container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyolefin-based plastic container in which a label having excellent sticking properties and chemical resistance is bonded to a container by sticking an in-mold label.

(Prior Art) Affixing a label indicating the contents to a hollow container increases the commercial value of the packaged product and invites consumers to purchase, and therefore has an important meaning in packaging technology.

It has been known for a long time to label a hollow container by an in-mold label operation, and the label to be attached to the inner surface of the cavity of the molding die is held by means such as vacuum suction,
A means for hollow-molding a plastic parison in this mold is generally employed (for example, Japanese Patent Laid-Open No. 61-202818).

Further, it is already known to use a laminate of a solid polymer layer, a foam layer and a polymer solution layer as a plastic label (JP-A-60-123333, 60-183343 and 60-242490).

As the label for operating the in-mold label, one based on a plastic film, which can be printed on the back side, has a clear image, and is preferably one having advantages such as excellent stain resistance, Further, from the viewpoint that the heat is applied to the wall of the plastic container that is being molded, it is advantageous to use a heat-sensitive adhesive, particularly a hot-melt adhesive.

(Problems to be Solved by the Invention) However, known hot-melt adhesives have not yet been satisfactory with respect to chemical resistance. In the case of a container used for cosmetics, toiletries, chemicals, etc., there is a drawback that the label is peeled off or the adhesive strength is lowered due to the action of the contents attached to the outside of the container at the time of filling or using. Further, in the case of a transparent label, there is a problem that the die line at the time of molding becomes a space between the bolt and the label and remains in the molded container, impairing the appearance.

Therefore, an object of the present invention is that a label is attached to a polyolefin plastic container by an in-mold label operation with excellent adhesive strength, and the adhesive portion of the formed label exhibits excellent chemical resistance. To provide a labeled polyolefin plastic container.

(Means for Solving the Problems) According to the present invention, it comprises a polyolefin-based plastic container and a label attached to the outer surface of the container, the label being a label substrate and chlorine provided on the surface thereof. In a labeled container, which comprises an adhesive layer of a blend of a modified polypropylene and a copolymer of ethylene and a carbonyl-containing ethylene-based monomer, and the label is bonded to the outer surface of the container by in-mold label sticking. , The adhesive layer is chlorinated polypropylene and ethylene and carbonyl-containing ethylene-based monomer
A blend containing 0.1 to 60% by weight of a copolymer in a weight ratio of 95: 5 to 20:80, and the chlorinated polypropylene has a chlorine content within the range of 10 to 50% by weight. There is provided a labeled container characterized by comprising a combination of two different types.

(Operation) The present invention can be formed in a mold by using an adhesive of a blend of chlorinated polypropylene and a copolymer of ethylene and a carbonyl-containing ethylene monomer as an adhesive for an in-mold label sticking label. It is based on the finding that excellent adhesion is achieved with a polyolefin-based plastic container, and the adhesion is improved, and that it exhibits excellent chemical resistance even when cosmetics, toiletries, and various chemicals adhere.

The chlorinated polypropylene used in the present invention has polypropylene as a basic skeleton, but has a part of hydrogen atoms replaced with chlorine atoms, and has polarity by the replacement of chlorine atoms. Therefore, chlorinated polypropylene is different from ordinary polypropylene in that it is soluble in a solvent such as an aromatic hydrocarbon and the film formation from this solution is easy. Moreover, the formed chlorinated polypropylene film has a feature that it is easily heat-bonded to polyolefin plastics such as various polyethylenes, polypropylenes, and propylene-ethylene copolymers.

Furthermore, the copolymer of ethylene and a carbonyl-containing ethylene-based monomer used in the present invention (hereinafter sometimes simply referred to as an ethylene-carbonyl-containing ethylene-based copolymer) is outstanding on the coated surface and the printed surface. It has the feature of exhibiting excellent adhesion.

This chlorinated polypropylene and a blend of ethylene and a carbonyl-containing ethylene-based monomer blend show excellent thermal adhesion to a polyolefin-based plastic container in a mold, while exhibiting excellent chemical resistance. The reason for this is considered to be as follows.

The heat-adhesive label for sticking the label to the container by the in-mold label operation requires the heat of the wall of the plastic container being molded to be heat-bonded in a short time. Since the ethylene-carbonyl-containing ethylene-based copolymer used in the invention has a relatively low melting point, the label and the container are initially bonded by the heat of the container wall, and then the chlorinated polypropylene chlorinated polypropylene is chlorinated. With the decrease in crystallinity accompanying the above and the maintenance of the relatively high crystal melting temperature peculiar to polypropylene, a secondary bond between the label and the container becomes possible, and the label on the container can be reliably bonded by the heat of the container wall. . Further, since the ethylene-carbonyl-containing ethylene-based copolymer is melted for a relatively long time, the adhesive has improved wettability with respect to the bottle surface,
There is no die line left.

Further, this chlorinated polypropylene has the above-mentioned crystal structure, and by being blended with the ethylene-carbonyl-containing ethylene-based copolymer, strong adhesion can be obtained as compared with those conventionally used alone. This makes it possible to prevent label peeling and decrease in adhesive strength due to dripping of shampoo, cosmetics, etc., and to obtain excellent chemical resistance.

Also, as chlorinated polypropylene, the chlorine content is 10
The adhesive force between the label and the bottle can be increased by using a combination of two kinds having different chlorine contents within the range of 50 to 50% by weight (see Table 1 described later).

(Preferred Embodiment of the Invention) Structure of Label The label used in the present invention comprises a label base material and an adhesive layer of chlorinated polypropylene provided on one surface thereof. The label substrate generally comprises a plastic film or a composite of a plastic film layer and a metal layer. As a matter of course, a printing ink layer is provided on either surface of the label substrate.

In FIG. 1 showing an example of the label of the present invention, the label 1 includes a plastic film substrate 2, a printing ink layer or a medium layer (a layer only of the resin portion of the printing ink) 3 and a printing ink provided on the back side thereof. It is composed of a blond adhesive layer (hereinafter sometimes simply referred to as a blend adhesive layer) 4 with chlorinated polypropylene and an ethylene-carbonyl-containing ethylene-based copolymer applied to the surface of the layer.

In FIG. 2 showing another example of the label used in the present invention, the label 1a is a plastic film substrate 2, a printing ink layer 3 provided on the back side thereof, and a metal vapor deposition layer provided on the printing ink layer. An adhesive primer is applied between the metal foil layer 5 and the blend adhesive layer 4 applied on the metal layer 5.

Further, the label used in the present invention may have a layer structure as shown in FIG. In Fig. 3, this label 1b
Is a laminate of an outer layer 2 of a plastic film, a printing ink layer 3 provided on the back side thereof, an intermediate layer 6 of a plastic film having a metal vapor deposition layer 5a on the surface, and an inner layer 4 of a blend adhesive. This label 1b is obtained by applying a plastic film printed product and a plastic film metal-deposited product with an adhesive or an adhesive primer in a positional relationship where the printing ink layer and the metal deposition layer face each other. It is formed by applying a blend adhesive on the surface of the laminated metal vapor deposition film side.

Also, a layered structure is possible as shown in FIG. In FIG. 4, this label 1c is a laminate of a plastic film outer layer 2, a printing ink layer 3 provided on the back side thereof, a plastic film intermediate layer 6 having a metal vapor deposition layer 5a on the inner surface, a blend adhesive, and an inner layer 5. Made of. In this label 1c, a plastic film printed product and a plastic film metal-deposited product are laminated via an adhesive in a positional relationship where the printing ink layer and the plastic film surface face each other. It is formed by applying an adhesive primer to the surface and then applying the blend adhesive on it.

The plastic film substrate 2 is generally uniaxially or biaxially stretched and transparent, so that the printed layer 3 can be seen through this film layer. The printing layer 3 is a so-called back surface printed with printing ink, and may be a multiple printing layer such as an image portion and a background, and the background may be a vapor-deposited or foil-shaped metal layer. .

Each material The chlorinated polypropylene used in the present invention preferably has a chlorine content in the range of 10 to 50% by weight, particularly 20 to 40% by weight, and further measured by a differential scanning calorimeter (DSC). , A crystal melting peak temperature (T ₁ ) of 130 to 50 ° C., especially 115
The heat of fusion of crystal (C) is preferably 0.1 to 10 cal / g, particularly 0.5 to 5 cal / g at -60 ° C.

When the chlorine content is less than the above range, the solubility is decreased and the film-forming operation becomes difficult, and the heat of crystal fusion becomes larger than the above range, and the adhesive strength due to the in-mold label sticking tends to decrease. There is. On the other hand, when the chlorine content is more than the above range, the polarity of the adhesive is too strong, and the adhesiveness to the polyolefin-based plastic is deteriorated. Further, if the peak temperature (T) is higher than the above range, the adhesiveness to the polyolefin-based plastic (during label operation in the mold) is lowered, and if it is lower than the above range, the heat resistance is lowered. If the amount of heat (C) is larger than the above range, the thermal adhesiveness during label operation in the mold is unsatisfactory, and if it is smaller than the above range, the heat resistance tends to be unsatisfactory.

FIG. 5 shows the DSC curve of the chlorinated polypropylene (Example 2) used in the present invention. This chlorinated polypropylene is composed of a combination of two kinds having different chlorine contents and has two peaks, a high melting point peak (T ₁ ) and a low melting point peak (T ₂ ).

In the present invention, the ethylene-carbonyl-containing ethylene-based copolymer is a carbonyl based on carboxylic acid, carboxylic acid anhydride, carboxylic acid ester, carboxylic acid amide or imide, aldehyde, ketone or the like. A copolymer of ethylene with an ethylenically unsaturated monomer containing is used.

Suitable examples of carbonyl-containing ethylenically unsaturated monomers include:
Without being limited to this, it is as follows.

A. Ethylenically unsaturated carboxylic acid Acrylic acid, methacrylic acid, maleic acid, fumaric acid,
Crotonic acid, itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid.

B. Ethylenically unsaturated carboxylic anhydride Maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride.

C. Ethylenic unsaturated ester acrylic ester, methyl methacrylate, 2-ethylhexyl acrylate, mono- or di-ethyl maleate, vinyl acetate, vinyl propionate, γ-hydroxypropyl methacrylate, β-hydroxyethyl acrylate, Glycidyl acrylate, glycidyl methacrylate.

D. Ethylenically unsaturated amide or imide Acrylamide, methacrylamide, maleimide.

E. Ethylenically unsaturated aldehydes or ketones Acrolein, methacrolein, vinyl methyl ketone, vinyl butyl ketone.

These carbonyl-containing ethylenically unsaturated monomers may be contained in the copolymer in an amount of 0.1 to 60% by weight, particularly 3 to 50% by weight. That is, when the amount of the carbonyl-containing ethylenically unsaturated monomer is lower than the above range, sufficient adhesiveness and processability may not be obtained when the coating amount is used, while when the amount is more than the above range. In some cases, the mechanical strength of this resin layer may decrease.

These carbonyl-containing ethylenically unsaturated monomers can be incorporated in the main chain or side chain of the polymer in the form of a so-called random copolymer, block copolymer or graft copolymer, The production of these copolymers is carried out by any means known per se.

Copolymers that are readily available and particularly suitable for the purposes of the present invention are, in order of importance, ethylene-vinyl acetate copolymer and ethylene-acrylic acid copolymer.

The molecular weight of the ethylene-carbonyl-containing ethylene-based copolymer used may be within a range sufficient to form a film, and in view of mechanical properties and processability, the melt index (MI) is 0.1 to 300 g / 10 minutes. Those in the range of are used.

In the present invention, a blend of this chlorinated polypropylene and an ethylene-carbonyl-containing ethylene-based copolymer is used as an adhesive. The proportion of this blend is preferably 95: 5 to 20:80, particularly 90:10 to 20:80 by weight of the chlorinated polypropylene: ethylene-carbonyl-containing ethylene-based copolymer. When the amount of chlorinated polypropylene is more than the above range, the initial adhesion due to the ethylene-carbonyl-containing ethylene-based copolymer becomes weak at the time of heat adhesion, and it is possible to obtain sufficient and reliable adhesiveness only by the heat of the container wall being molded. It also becomes difficult and the wettability of the adhesive decreases, leaving a die line. Further, if the amount of chlorinated polypropylene is less than the above range, the secondary adhesion due to chlorinated polypropylene also deteriorates, and sufficient adhesiveness cannot be obtained.

This blend comprises aromatic hydrocarbons such as toluene, ethylbenzene, xylene; halogenated hydrocarbons,
For example, trichlorethylene, tetrachloroethylene,
Methyl chloroform: soluble in alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane and the like, and applied in the form of this solution and dried to form a film on the adhesive layer.

This blend is at a concentration of 15g / 100ml in toluene at 20 ° C.
0.1 to 200 poise, especially 0.1 to 50, measured at a temperature of
It preferably has a poise viscosity. The thickness of the adhesive layer is preferably in the range of 0.1 to 50 μm, particularly 1 to 10 μm.

Various compounding agents such as tackifiers, heat stabilizers, lubricants, plasticizers and fillers can be compounded in the adhesive layer used in the present invention. As the tackifier, a rosin resin, a terpene resin, a petroleum resin, a styrene resin, a cumarone-indene resin, or the like can be used. As the heat stabilizer, a metal soap-based stabilizer or an organic tin-based stabilizer is used. As a lubricant, an epoxy-based lubricant or a wax-based lubricant is used, as a plasticizer, dioctyl phthalate, fatty acid mono- or diglyceride is used, and as a filler, inorganic or polymer microbeads are used.

In the present invention, examples of the plastic constituting the base film of the label include crystalline polypropylene, crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly-4-methylpentene-1, low-, medium-
Alternatively, polyolefins such as high-density polyethylene; aromatic vinyl polymers such as polystyrene and styrene-butadiene copolymers; halogenated vinyl polymers such as polyvinyl chloride and vinylidene chloride resins; acrylonitrile-styrene copolymers, acrylonitrile-styrene. -Nitrile polymers such as butadiene copolymers; nylon 6, nylon 6,
6. Polyamides such as para or meta-xylylene adipamide; polyesters such as polyethylene terephthalate and polytetramethylene terephthalate; various polycarbonates; thermoplastic resins such as polyacetals such as polyoxymethylene.

This stretched film is generally 20 to 300 μm, especially 50
It is preferable to have a thickness of ˜150 μm.

As the metal layer, a foil or vapor deposition layer of a metal having a metallic luster such as aluminum, tin, and copper is used. As the foil, one having a thickness of 1 to 15 μm, particularly 5 to 9 μm is generally used, while in the case of a vapor deposition layer, a foil having a thickness not more than the thickness of the foil is used.

The lamination of the printed stretched film substrate and the metal foil, or the lamination of the printed stretched film substrate and the metal vapor deposition film,
A urethane-based adhesive, an epoxy-based adhesive, or an acid-modified olefin resin-based adhesive may be used depending on the film substrate.

In the present invention, the plastic film substrate is not necessarily limited to a transparent one, and for example, a foamed stretched plastic film can be used. In this case, the printing ink layer is provided on one surface (front surface side) of the foamed film, and the adhesive is provided on the other surface (back surface side).

When a blended adhesive layer is provided on the printing ink layer, use a printing ink containing a chlorinated polypropylene-based or polyester urethane-based resin, polyvinyl urethane-based resin, or polyvinyl chloride urethane resin as a binder. Which gives good adhesion between the two layers.

In-mold label operation In FIG. 6 for explaining the in-mold label operation, in step A, prior to blow molding of the plastic parison, the blow split molds 7a and 7b are in an open state, and at least one of these cavities is opened. The label 1 is applied to the surface 8 in advance. That is, the cavity surface 8 has a portion for supporting the label 1, and the reduced pressure suction mechanism 9 is provided in this portion.
Is held. In this case, the label has a positional relationship in which the plastic film substrate 2 is on the outside and the hot melt adhesive resin layer 5 is on the inside. The application and fixing of the label 1 to the cavity surface 8 can be performed not only by suction but also by static electricity, for example.

Next, in step B, the molten plastic parison 11 is extruded from the die 10, the blow molds 7a and 7b are closed, and pressurized gas is blown into the closed parison 11.

In step C, the parison that expands in the mold is held on the mold surface and pressed against the label 1 to bring them into close contact, and the expanded parison comes into contact with the mold surface and is cooled, whereby the labeled container 12 Becomes

For blow molding, in addition to the direct blow method using a horizontal rotary blow molding machine, a vertical rotary blow molding machine, etc., injection blow, two-stage blow,
It can be performed by any blow molding method such as sheet forming and stretch blow.

Of course, the in-mold label operation used in the present invention is not limited to blow molding or hollow molding, but can be widely applied to thermoforming such as injection molding, vacuum molding, and plug assist molding.

As the polyolefin plastic constituting the container, those exemplified for the film are widely used.
This container can have a single-layer or multi-layer structure.For example, a container composed of a single layer of polyolefin, or a multi-layer having a polyolefin as an inner and outer layer and a gas barrier thermoplastic resin provided as an intermediate layer therebetween. Containers.

Examples of the gas barrier resin include ethylene-vinyl alcohol copolymers having an ethylene content of 50 to 20 mol%; xylylene group-containing polyamides; gas barrier polyesters; high nitrile group-containing polymers; vinylidene chloride resins and the like. A gas barrier resin known per se can be used. When there is no adhesiveness between the inner and outer layers and the intermediate layer, an adhesive resin such as an acid-modified olefin resin, various copolyamides, and various copolyesters may be contained between them.

(Effect of the Invention) According to the present invention, by using a blend of chlorinated polypropylene and a copolymer of ethylene and a carbonyl-containing ethylene-based monomer as an adhesive for an in-mold label sticking label, Excellent adhesion is achieved to the polyolefin plastic container molded with, and the formed adhesive part has the advantage of exhibiting excellent chemical resistance even when cosmetics, toiletries, and various chemicals adhere. Was obtained.

(Example) The present invention will be described with the following example.

Example 1. On one surface of a stretched polypropylene film having a thickness of 100μ, printing is performed with an ink using polyester urethane as a binder, and a medium of polyester urethane is further applied thereon, and a chlorine content of 26 is applied on the medium. % By weight, crystal melting peak temperature is 100 ° C., crystal melting heat is 2.2
Cal / g chlorinated polypropylene A, chlorine content is 35% by weight, crystal melting peak temperature is 50 ° C, heat of crystal melting is
Chlorinated polypropylene B of 0.8 cal / g and an ethylene-vinyl acetate copolymer having MI of 80 and vinyl acetate content of 43% are 30: 3.
The blended mixture at a ratio of 5:35 was applied to a film thickness of 1.5 μm to form an adhesive layer.

Next, a 90 mm long, 60 mm wide rectangular label was punched out from the obtained label base material, and the melting point was 15 by the process shown in FIG.
It was attached to the surface of a bottle made of an ethylene-propylene copolymer at 8 ° C. In this case, the molten resin temperature of the ethylene-propylene copolymer parison was 210 ° C and the blow mold temperature was 7 ° C.

The appearance of the in-mold label bottle thus obtained was very good.

Also, when the adhesive strength between the label and the bottle was measured, when sampling in the bottle height direction (HD), 540 g / 1
5mm width 780g / 15m when sampled in the bottle lateral direction (WD)
It was m wide. (A 90 ° peel test was performed at a peeling speed of 300 mm / min.) Next, in order to test the adhesiveness of the label due to the adhesion of the contents, the in-mold label bottle was immersed in a rinse and shampoo at 40 ° C. for 24 hours. . As a result, the appearance of the label was not abnormal for any of the contents. Adhesive strength was almost the same with the rinse HD ・ ・ 500g / 15mm width and the shampoo HD ・ ・ 530g / 15mm width. Further, the in-mold label bottle was filled with water and left at 5 ° C. for one day. Then, as a drop test, the bottle was dropped from the height of 1.2 m 5 times each vertically and horizontally on the concrete surface, but the label was not peeled off.

Example 2 and Comparative Examples 1 to 4 Labels were prepared in the same manner as in Example 1 using various adhesives having different blend ratios of chlorinated polypropylene and ethylene vinyl acetate copolymer, and in-mold label bolts were prepared. After molding, the appearance and the adhesive strength were evaluated. An immersion test was also conducted, and the results are shown in Table 1. The same chlorinated polypropylene and EVA were used as in Example 1.

Examples 3 to 4 and Comparative Examples 5 to 8 A label was prepared in the same manner as in Example 1 except that the molding bottle material was HDPE with a melting point of 131 ° C., an in-mold label bottle was molded, and the appearance and adhesive strength were evaluated. The results of the immersion test are shown in Table 1.

[Brief description of the drawings]

FIGS. 1, 2, 3, and 4 are views showing examples of the cross-sectional structure of the label of the present invention, FIG. 5 is a DSC curve of chlorinated polypropylene, and FIG. FIG. Reference numeral 1 is a label, 2 is a plastic film, 3 is a printing ink layer, 4 is a chlorinated polypropylene adhesive layer, 5
Is a metal layer, 5a is a metal vapor deposition layer, 6 is a plastic film, 7 is a blow mold, 8 is a cavity surface, 9 is a vacuum suction mechanism, 10 is a die, 11 is a parison, and 12 is a labeled container.

Claims (1)

(57) [Claims] 1. A polyolefin-based plastic container and a label affixed to the outer surface of the container, the label comprising a label base material, chlorinated polypropylene provided on the surface of the label base material, ethylene and a carbonyl-containing ethylene-based unit amount. In a labeled container in which the label is bonded to the outer surface of the container by in-mold label sticking, the adhesive layer comprises a chlorinated polypropylene and ethylene. And a carbonyl-containing ethylene-based monomer 0.1 to 60% by weight of a blend containing 95: 5 to 20:80 by weight, and chlorinated polypropylene has a chlorine content of 10 to 50% by weight. A labeled container comprising a combination of two kinds having different chlorine contents within the range of%.