JP2519531B2 - In-mold label sticker label and labeled container - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an in-mold label sticking label, and more particularly, it is used for sticking an in-mold label to a polyolefin container and has excellent chemical resistance. The present invention relates to a label having the label and a labeled container using the label.

(Prior Art) Affixing a label for displaying contents on a hollow container has an important meaning in packaging technology because it enhances the commercial value of packaging products and motivates consumers to purchase.

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 sufficiently satisfactory in 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. Furthermore, in the case of a transparent label, there is a problem that the die line at the time of molding becomes a gap between the bottle and the label and remains in the molded container, impairing the appearance.

Therefore, an object of the present invention is to perform in-mold label operation, which can be applied to a polyolefin-based plastic container with excellent adhesive strength, and in which the adhesive portion of the formed label has excellent chemical resistance. To provide a label sticking label.

Another object of the present invention is to provide a polyolefin-based plastic container to which the above label is attached.

(Means for Solving Problems) According to the present invention, there is provided a label to be bonded to the outer surface of a polyolefin container by attaching a label in a mold, which comprises (a) a transparent label substrate and (b) a label substrate. From the printing ink layer applied to the inner surface side of (3) and (c) the chlorinated polypropylene or the blend of the chlorinated polypropylene and the ethylene-carbonyl-containing ethylene-based monomer copolymer provided on the printing ink layer. And (d) an adhesive for an ethylene copolymer mainly composed of ethylene and containing an ethylenically unsaturated carboxylic acid or its anhydride, salt or ester as a copolymerization component, which is provided on the primer layer. Provided is an in-mold label sticking label having excellent chemical resistance, which is characterized by comprising a laminate with layers.

(Operation) In the present invention, from the viewpoint of image sharpness and stain resistance,
A printing ink layer is provided on the inner surface side of the transparent label substrate, and a primer layer made of chlorinated polypropylene or a blend of chlorinated polypropylene and an ethylene-carbonyl-ethylene-based monomer copolymer is provided on the printing ink layer. It is characterized in that an ethylene-based copolymer containing ethylene as a main component and an ethylene-based unsaturated carboxylic acid or its anhydride, a salt or an ester as a copolymerization component provided on the primer layer is provided as an adhesive layer, As a result, excellent adhesion is achieved with the polyolefin-based plastic container molded in the mold, and the adhesion is improved, and excellent chemical resistance is obtained even when cosmetics, toiletry products, and various chemicals adhere. It is a thing.

First, since the ethylene-based copolymer used in the present invention contains ethylene as a main monomer constituent component, it not only exhibits excellent adhesiveness to an olefin-based plastic container, but also has a polar main chain or side chain. Since it contains a certain ethylenically unsaturated carboxylic acid or its anhydride, salt or ester, it also exhibits excellent adhesiveness to the printing ink layer. In addition, because this copolymer is predominantly composed of ethylene polymer chains, it has a relatively low temperature (typically 60
The heat of the polyolefin container, which is melted at a temperature of 120 to 120 ° C.) and is being molded in the mold, provides strong thermal adhesion in a short time.

In the present invention, an ethylenically unsaturated carboxylic acid or an anhydride thereof, an ethylene copolymer containing a salt or ester as a copolymerization component, when used as an adhesive for an in-mold label sticking label, has excellent chemical resistance. The fact of showing has been found as a phenomenon as a result of extensive experimentation, and the reason is not yet clear enough. However, according to the study of the present inventors, the decrease in adhesive force that occurs when a label-attached container comes into contact with a chemical such as a surfactant is considered to be due to a kind of stress cracking (environmental crack). It is presumed that the ethylene-based copolymer used in (1) has excellent chemical resistance as an adhesive layer because it has excellent stress cracking resistance. This estimation is also in good agreement with the fact that ethylene-ethyl acrylate copolymer (EEA) exhibits remarkably excellent resistance to stress cracking against ordinary polyethylene.

One feature of the label of the present invention is to interpose the ethylene-based copolymer on a printing ink layer with a primer layer.

When a chlorinated polypropylene or a combination of chlorinated polypropylene and a copolymer of ethylene and a carbonyl-containing ethylene-based monomer is used as such a primer layer, the adhesion with the printing ink layer and its durability are further improved. I found out that Moreover, this primer also offers the advantage of being easy to apply on the printing ink layer.

(Preferred Embodiment of the Invention) The label of the present invention is provided on a transparent label base material, a printing ink layer applied on the inner surface side of the label base material, a primer layer provided on the printing ink layer, and a primer layer provided on the printing ink layer. It consists of a four-layer laminate of the adhesive layer of the specific ethylene copolymer.

In FIG. 1 showing an example of the label of the present invention, the label 1 comprises a plastic film substrate 2, a printing ink layer 3 provided on the back side (the side which becomes the inner surface), and a primer layer provided thereon ( 6) and ethylene as a main component, and a four-layer laminate with an adhesive layer 4 of an ethylenic copolymer containing an ethylenically unsaturated carboxylic acid or its anhydride, salt or ester as a copolymerization component.

The plastic film substrate 2 is generally uniaxially or biaxially stretched and transparent, and the printed layer 3 is 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 as already mentioned, the background is a metal layer such as a vapor deposition or foil shape. May consist of

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: polystyrene, aromatic vinyl polymers such as styrene-butadiene copolymer: vinyl halides such as polyvinyl chloride and vinylidene chloride resin: acrylonitrile-styrene copolymer, acrylonitrile-styrene -Nitrile polymers such as butadiene copolymers: nylon 6, nylon 6,
6, polyamides such as para or metaxylylene 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 printing ink, all the inks widely used for printing on this kind of plastic film can be used, but preferably a two-component reaction type ink, for example, an epoxy resin and a resin containing a hydroxyl group, an amino group or a carboxyl group is used. A vehicle in which a combination or a combination of a urethane resin and a polyester, an acrylic resin or a vinyl resin is used and an organic or inorganic pigment is dispersed is used. Also, if a transparent portion is required, only the vehicle is used. On the other hand, as the metal layer, a foil or a 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 equal to or less than that of the foil is used.

The specific ethylene copolymer used in the present invention is a means such as random copolymerization, block copolymerization or graft copolymerization of an ethylenically unsaturated carboxylic acid or its anhydride, its alkyl ester, its metal salt or organic base salt. so,
It is incorporated in the ethylene polymer chain or in the side chain of the ethylene polymer chain.

 A suitable example is shown below.

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 Carboxylic Acid Esters Ethyl Acrylate, Butyl Acrylate, Methyl Methacrylate, Ethyl Methacrylate, 2-Ethylhexyl Acrylate, Mono- or Di-Ethyl Maleic Acid γ-Hydroxy Methacrylate, β-Hydroxy Acrylic Acid Ethyl, glycidyl acrylate, glycidyl methacrylate.

D. Sodium acrylate, sodium methacrylate, zinc acrylate, zinc methacrylate.

The ethylene-based copolymer used in the present invention has an ethylenically unsaturated carboxylic acid or its derivative as a C = 0 (carbonyl) group, 1 to 300 meq / 100 g, particularly 1 to 20.
It is preferable that the content is 0 meq / 100 g in terms of adhesion and chemical resistance. Further, this ethylene-based copolymer, measured by JIS K 6730, 0.1 to 400 dg / min, especially
It is desirable to have a melt flow rate (MFR) of 0.5 to 300 dg / min.

Examples of suitable ethylene-based copolymers include maleic anhydride-grafted polyethylene, ethylene-ethyl acrylate copolymers, ionomers (ionically cross-linked ethylene copolymers) and the like.

The ethylene-based copolymer is generally 0.01 to 100μ
The thickness of the adhesive layer is preferably 0.1 to 50 μm, and the adhesive layer can be formed by an extrusion coating method, heat fusion of a film or powder, or application of a dispersion or solution.

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, rosin-based resin, terpene-based resin, petroleum resin, styrene-based resin, coumarone-indene resin and the like can be used. As the heat stabilizer, a metal soap-based stabilizer or an organic tin-based stabilizer is used. Epoxy lubricants and wax lubricants are used as lubricants, dioctyl phthalate, fatty acid mono- or diglycerides are used as plasticizers, and inorganic or polymer microbeads are used as fillers.

The chlorinated polypropylene used as the primer layer is
A chlorine content in the range of 10 to 50% by weight, particularly 20 to 40% by weight is preferable, and a differential scanning calorimeter (DS
C) with a peak melting temperature (T ₁ ) of 130 to 50
℃, especially 115 ~ 50 ℃, heat of fusion of crystal (C) 0.1 ~
It is preferably in the range of 10 cal / g, especially 0.5 to 5 cal / g.

Although it is possible to use chlorinated polypropylene alone in the primer layer, it is preferable to use it in the form of a blend with an ethylene-carbonyl-containing ethylene-based monomer copolymer.
Better adhesion is obtained. As the carbonyl-containing ethylene-based copolymer, a copolymer of ethylene-ethylenically unsaturated carboxylic acid or its derivative described in the adhesive layer is used, and a copolymer of ethylene and vinyl ester such as vinyl acetate is used. Coalescence is advantageously used. The content of the carbonyl-containing monomer in the copolymer is in the range of 0.1 to 60% by weight, particularly 1 to 50% by weight.

Copolymers that are easily available and particularly suitable for the purpose of the present invention are an ethylene-vinyl acetate copolymer and an ethylene-acrylic acid copolymer, in the order of importance. The molecular weight of the ethylene-containing carbonyl-ethylene-based copolymer used may be within a range sufficient to form a film, and from the viewpoint of mechanical properties and processability, the melt index (MI) is 0.1 to 300.
The g / 10 min range is used.

The ratio of this blend is 95: 5 to 2 for the chlorinated polypropylene: ethylene-carbonyl-containing ethylene-based copolymer.
A weight ratio of 0:80, especially 90:10 to 20:80, is preferred.

This blend contains aromatic hydrocarbons such as toluene, ethylbenzene, xylene: halogenated hydrocarbons,
For example, trichlorethylene, tetrachloroethylene,
Methyl chloroform: It is soluble in alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, and ethylcyclohexane, and is applied in the form of this solution and dried to form a film on the primer layer. This blend had a concentration of 15 g / 100 ml in toluene, measured at a temperature of 25 ° C. of 0.1
It preferably has a viscosity of from about to 200 poises, especially from 0.1 to 50 poises. The thickness of the primer layer is 0.1 to 5
It is preferably in the range of 0 μm, particularly 1 to 10 μm.

In FIG. 2 for explaining the in-mold label operation, in step A, prior to the blow molding of the plastic parison, the plow split molds 7a, 7b are in an open state, and the cavity surface 8 of at least one of them is Label 1 is applied 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 plastic film substrate 2 on the outside and an adhesive resin layer 4 of an ethylene copolymer.
Is the inner side. 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 ballison 11 is extruded from the die 10, the blow split molds 7a and 7b are closed, and pressurized gas is blown into the closed ballison 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, and can be widely applied to thermoforming such as injection molding, vacuum molding, plug assist molding and the like.

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 multilayer in which polyolefin is used as inner and outer layers and a gas barrier thermoplastic resin is provided as an intermediate layer therebetween. Examples include 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.

(Effects of the Invention) According to the present invention, ethylene is the main component and an ethylenically unsaturated carboxylic acid or its anhydride is provided on the printing ink layer provided on the back side of the transparent film substrate via the chlorinated polypropylene-containing primer layer. By providing an ethylene copolymer containing a salt or ester as an adhesive layer, excellent adhesion is performed to the polyolefin plastic container molded in the mold, and the formed adhesive part is It has the advantage of exhibiting excellent chemical resistance even when cosmetics, toiletries, and various chemicals adhere.

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

Example 1 On one side of a stretched polypropylene film having a thickness of 100μ, printing was performed with an ink using polyester urethane as a binder, and further, a chlorine content rate was 26% by weight.
The crystal melting peak temperature is 90 ° C, and the heat of crystal melting is
Chlorinated polypropyne A of 2.2 cal / g and chlorine content of 35% by weight, crystal melting peak temperature of 62 ° C, crystal melting heat quantity
Chlorinated polypropylene B of 0.8 cal / g and 50: 2 of ethylene-vinyl acetate copolymer having MI of 80 and vinyl acetate content of 43%.
Blend the mixture at a ratio of 5:25 to a film thickness of 1.5μ, and further add ethyl acrylate content 25
The adhesive layer was formed so that the ethylene-ethyl acrylate copolymer (EEA), which had a crystal melting peak temperature of 75 ° C and a melt flow rate of 5 dg / min, was 4% in weight.

Then, a rectangular label measuring 100 mm in length and 80 mm in width was punched out from the obtained label substrate, and the melting point was 110% by the process shown in FIG.
A low-density polyethylene having a temperature of ℃ was applied to the outer surface layer, and a high-density polyethylene having a melting point of 130 ° C. was applied to the surface of the multilayer bottle.

In this case, the molten resin temperature was 200 ° 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, it was 750g / 15mm when sampled in the bottle height direction (HD).
Width, 790 g / 1 when sampled in the bottle lateral direction (WD)
It was 5 mm wide (a 90 ° C peel test was performed at a peeling speed of 300 mm / min).

The in-mold label bottle was then dipped in shampoo at 40 ° C. for 24 hours to test the label's adhesiveness due to content sticking. As a result, the appearance of the label was not abnormal for any of the contents. The adhesive strength was also good, with HD 560g / 15mm width and WD 700g / 15mm width.

Further, after filling an in-mold label bottle with water and leaving it at 5 ° C. for 1 day, the bottle was dropped from the height of 1.2 m to the concrete surface 5 times each vertically and horizontally, but there was no peeling of the label.

Examples 2 to 8 Comparative Examples 1 to 4 In-mold label bottles were formed by changing the ethyl acrylate content of the adhesive EEA in Example 1 and using various polymers as adhesives instead of EEA. Then, the appearance and adhesive strength were evaluated, and the results of the immersion test in shampoo and the drop test are shown in Table 1.

Comparative Example 5 On one surface of a stretched polypropylene film having a thickness of 100 μm, printing was performed with an ink using polyvinyl urethane as a binder, and then a medium of polyvinyl urethane ink was applied thereon, and an ethyl acrylate content rate was applied thereon. Of 25% by weight and a crystal melting peak temperature of 70 ° C. and a melt flow rate of 275 dg / min, an adhesive layer was formed into a film having a thickness of 5 μm.

Then, a rectangular label measuring 100 mm in length and 80 mm in width was punched out from the obtained label, and the low-density polyethylene having a melting point of 110 ° C was used as the outer layer and the high-density polyethylene having a melting point of 130 ° C was used as the inner layer by the process shown in Fig. 2. Attached to the surface of the multi-layer bottle.

In this case, the molten resin temperature was 200 ° 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, it was 500 g / 15 mm when sampled in the bottle height direction (HD).
400g / 1 when sampled in width and bottle width direction (WD)
The width was 5 mm and the adhesive strength was poor. (300mm /
A 90 ° C peel test was performed at a peel rate of minutes).

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 shampoo at 40 ° C. for 24 hours, but there was no abnormality in the label in appearance.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a cross-sectional structure of a label of the present invention, and FIG. 2 is a diagram showing an in-mold label operation. Reference numeral 1 is a label, 2 is a plastic film, 3 is a printing ink layer, 4 is an adhesive layer, 6 is a primer, 7 is a blow split mold, 8 is a cavity surface, 9 is a vacuum suction mechanism, 10
Is a die, 11 is a parison, 12 is a labeled container.

Claims (2)

(57) [Claims] 1. A label to be bonded to the outer surface of a polyolefin container by applying an in-mold label, wherein (a) a transparent label base material and (b) a printing ink applied to the inner surface side of the label base material. Layer and (c) provided on the printing ink layer,
A primer layer composed of chlorinated polypropylene or a blend of chlorinated polypropylene and an ethylene-carbonyl-containing ethylene-based monomer copolymer, and (d) ethylene as a main component and a copolymerization component provided on the primer layer. An in-mold label with excellent chemical resistance, comprising a laminate with an adhesive layer of an ethylene copolymer containing an ethylenically unsaturated carboxylic acid or its anhydride, salt or ester. 2. A polyolefin container and a label attached to the outer surface of the container, the label comprising the laminate according to claim 1, the label being attached to the outer surface of the container by applying an in-mold label. Labeled container with excellent chemical resistance, which is characterized by