JPH02135271A - Label for label pasting in mold and container with label - Google Patents

Abstract

PURPOSE:To obtain the title label having excellent chemical resistance by equipping an adhesive layer at the tacky face side of label base material with a blend of chlorinated polypropylene and a copolymer of ethylene and a carbonyl- containing ethylene-based monomer. CONSTITUTION:A blend of chlorinated polypropylene and a copolymer of ethylene and a carbonylated ethylene-based monomer is set as an adhesive layer at the tacky face side of label base material to give the aimed label. The label is bonded to the outer surface of a polyolefin-based plastic container by label pasting in mold.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a label for in-mold labeling, and more specifically, a label that is used for in-mold labeling to polyolefin containers and has excellent chemical resistance. and a labeled container using this label.

(Prior Art) Attaching a label indicating the contents to a hollow container has an important meaning in terms of packaging technology because it increases the commercial value of the packaged product and stimulates consumers' desire to purchase the product.

It has been known for a long time to apply labels to hollow containers by in-mold label operation.The label to be affixed to the inner surface of the cavity of a molding mold is held by means such as vacuum suction, and the plastic is A method of blow-molding the balisong is generally adopted (for example, Japanese Patent Application Laid-Open No. 61-2028
18 Publication) 6 In addition, as a plastic label, a solid polymer layer,
It is also already known to use a laminate of a foam layer and a polymer solution layer (JP-A-60-123333.60-1).
83343 and 60-242490).

As a label for operation of an in-mold label, it is desirable to use one based on plastic film, which has advantages such as being able to print on the back side, having a clear image, and having excellent stain resistance. It is also advantageous to use heat-sensitive adhesives, especially hot-melt adhesives, in that the heat of the plastic container wall being molded is used to effect the bonding.

(Problems to be Solved by the Invention) However, known hot melt adhesives have not yet been fully satisfactory in terms of chemical resistance. cosmetics,
In the case of containers used for toiletries, medicines, etc.
The label may peel off or the adhesive strength may decrease due to the contents adhering to the outside of the container during filling or use.

Furthermore, in the case of transparent labels, there is a problem in that the guinea pigs lines formed during molding become floating between the bottle and the label and remain on the molded container, impairing its appearance.

Therefore, an object of the present invention is to provide an in-mold label that can be attached to a polyolefin plastic container with excellent adhesive strength by an in-mold label operation, and in which the adhesive portion of the formed label has excellent chemical resistance. We provide labels for labeling.

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

(Means for Solving the Problems) According to the present invention, there is provided a label that is bonded to the outer surface of a polyolefin plastic container by in-mold label attachment, in which chlorinated polypropylene is attached to the attachment surface side of the label base material. The present invention also provides a label comprising a blend of a copolymer of ethylene and a carbonylethylene-containing monomer as an adhesive layer.

According to the present invention, the present invention also provides a polyolefin-based plastic container comprising a polyolefin-based plastic container and a label affixed to the outer surface of the container; and an adhesive layer of a blend of a copolymer with a monomer, the label being bonded to the outer surface of the container by in-mold labeling.

(Function) The present invention provides that when an adhesive made of a blend of chlorinated polypropylene and a copolymer of ethylene and a carbonyl ethylene-containing monomer is used as an adhesive for in-mold labels, molding can be performed in a mold. This is based on the knowledge that it provides excellent adhesion and improved adhesion to polyolefin-based plastic containers, and exhibits excellent chemical resistance even when cosmetics, toiletries, and various chemicals adhere to it.

The chlorinated polypropylene used in the present invention has a basic skeleton of polypropylene, but some of the hydrogen atoms are replaced with chlorine atoms, and it has polarity due to the substitution of the chlorine atoms. Therefore, chlorinated polypropylene is different from ordinary polypropylene in that it is soluble in solvents such as aromatic hydrocarbons, and it is easy to form films from this solution. Moreover, the formed film of chlorinated propylene has the characteristic that it can be easily thermally bonded to various polyethylene, polypropylene, propylene-ethylene copolymers, and other botanical olefin plastics.

Furthermore, the copolymer of ethylene and a carbonylethylene-containing monomer used in the present invention (hereinafter sometimes simply referred to as an ethylene-carbonylethylene-containing monomer) has a noticeable effect on painted surfaces and printed surfaces. It is characterized by excellent adhesion.

This blend of chlorinated polypropylene and a copolymer of ethylene and a carbonyl ethylene-containing monomer exhibits excellent thermal adhesion to polyolefin plastic containers in the mold, while also exhibiting excellent chemical resistance. This is thought to be due to the following reasons.

Heat-adhesive labels, which are used to attach labels to containers using in-mold label operations, require thermal adhesion using the heat of the plastic container wall that is being molded for a short period of time. Since the ethylene-containing carbonyl ethylene copolymer used in the invention has a relatively low melting point, the label and container are initially bonded together by the heat of the container wall, and then the chlorinated polypropylene is chlorinated. The reduction in crystallinity associated with polypropylene and the maintenance of a relatively high crystalline melting temperature characteristic of polypropylene enable secondary adhesion between the label and the container, resulting in a label that reliably adheres to the container using the heat from the container wall. . In addition, since the ethylene-containing carbonyl edisin copolymer is melted for a relatively long time, the adhesive has improved wettability to the bottle surface and no Glyline remains.

In addition, because this chlorinated polypropylene has the above-mentioned crystal structure and is blended with an ethylene-containing carbonyl ethylene copolymer, it has stronger adhesion than conventionally used individually. This prevents peeling of the label and decrease in adhesive strength due to dripping of shampoo, cosmetics, etc., and provides excellent chemical resistance.

(Preferred Embodiment of the Invention) The label of the present invention comprises a label base material and an adhesive layer of chlorinated polypropylene applied to one surface thereof. Label substrates generally consist of a plastic film or a composite of a plastic film layer and a metal layer. Naturally, a printing ink layer is provided on either side of the label base material.

In FIG. 1 showing an example of the label of the present invention, this label l consists of a plastic film base material 2, a printing ink layer or medium layer (a layer consisting only of the resin portion of the printing ink) 3 applied to the back side of the plastic film base material 2, and a printing ink layer or medium layer (a layer containing only the resin portion of the printing ink) 3. It consists of an adhesive layer (hereinafter sometimes simply referred to as a blend adhesive layer) 4 of a blend of chlorinated polypropylene and an ethylene-containing carbonyl ethylene copolymer applied to the surface of the layer.

In FIG. 2 showing another example of the label of the present invention, this label 1a consists of a plastic film base material 2, a printing ink layer 3 applied to the back side of the plastic film base material 2, and a metal vapor deposition layer provided on the printing ink layer. An adhesive brider is applied between the metal foil layer 5 and the blend adhesive layer 4 applied over the metal layer 5.

Further, the label of the present invention can also have a layered structure as shown in FIG. In FIG. 3, this label 1b is made of a laminate of an outer plastic film layer 2, a printing ink layer 3 applied to the back side, a plastic film intermediate layer 6 having a metallized layer 5a on the surface, and an inner blend adhesive layer 4. It has become. This label lb is made by pasting together a plastic film printed on and a plastic film coated with metal vapor deposited using an adhesive or an adhesive brusher, with the printing ink layer and metal vapor deposited layer facing each other. It is formed by applying a blend adhesive to the side of the laminated metallized film.

Furthermore, a layered structure as shown in FIG. 4 is also possible. Fourth
In the figure, this label IC consists of a laminate of a plastic film outer layer 2, a printing ink layer 3 applied on the back side, a plastic film intermediate layer 6 having a metal vapor deposited layer 5a on the inner surface, a blend adhesive, and an inner layer 4. ing.

This label 1c is made by pasting together a printed plastic film and a plastic film coated with metal vapor deposition using an adhesive so that the printing ink layer and the plastic film surface face each other with an adhesive. It is formed by applying an adhesive brider to the surface and applying a blend adhesive over it.

The plastic film substrate 2 is generally uniaxially or biaxially stretched and transparent, so that the printed layer 3 is visible through the film layer.

The printing layer 3 is a so-called back-printed layer of printing ink, and may be a multiple printing layer such as an image area and a background, or the background may be made of a metal layer in the form of vapor deposition or foil. .

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 is further tested by differential scanning calorimetry (DSC).
When the crystal melting peak temperature (T, ) is measured at 130 to 60°C, especially 1) 5 to 60°C, the heat of crystal fusion f4 (
C) is 0.1 to 1 Ocaf2/g, especially 0.5 to 5
It is preferably within the range of caf2/g.

If the chlorine content is less than the above range, the solubility will decrease, making the film forming operation difficult, and the heat of crystal fusion will be greater than the above range, which will tend to reduce the adhesive strength when attaching the label in the mold. There is.

On the other hand, if the chlorine content is higher than the above range, the polarity of the adhesive will be too strong and the adhesiveness to polyolefin plastics will decrease. Furthermore, if the peak temperature (T) is higher than the above range, the adhesion to polyolefin plastics (during in-mold labeling operation) will decrease, and if it is lower than the above range, the heat resistance will decrease. If the amount of heat (C) is greater than the above range, the heat adhesion during in-mold label operation will be unsatisfactory, and if it is less than the above range, the heat resistance will likely be unsatisfactory.

Figure 5 shows the DS of chlorinated polypropylene used in the present invention.
A C curve is shown.

In the present invention, the ethylene-containing carbonylethylene copolymer includes a carbonyl (-C-) group based on carboxylic acid, carboxylic acid anhydride, carboxylic acid ester, carboxylic acid amide or imide, aldehyde, ketone, etc. A copolymer of an ethylenically unsaturated monomer and ethylene is used.

Suitable examples of the carboxyl-containing ethylenically unsaturated monomer include, but are not limited to, the following.

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, ethylenically unsaturated ethyl acrylate, 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 imidoacrylamide, methacrylamide, maleimide.

E. Ethylenically unsaturated aldehyde or ketone acrolein, methacrolein, vinyl methyl ketone, vinyl butyl ketone.

These carbonyl-containing ethylenically unsaturated monomers are contained in the copolymer in an amount of 0.1 to 60% by weight, particularly 3 to 50% by weight.
can be contained in an amount of That is, if the amount of the carbonyl ethylenically unsaturated monomer is lower than the above range, sufficient adhesion and processability may not be obtained when used as a coating layer, whereas if it is greater than the above range for,
The mechanical strength of this resin layer may decrease.

These carbonyl ethylenically unsaturated monomers can be incorporated into the main chain or side chain of the polymer in the form of a so-called random copolymer, block copolymer, graft copolymer, etc. These copolymers can be produced 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 copolymers and ethylene-acrylic acid copolymers.

The molecular weight of the ethylene-containing carbonyl ethylene copolymer used may be within a range sufficient to form a film, and from the viewpoint of mechanical properties and processability, the melt index (M I ) is 0.1 to 300 g. /10 minutes range is used.

In the present invention, a blend of this chlorinated polypropylene and an ethylene-containing carbonyl ethylene copolymer is used as an adhesive. The ratio of this blend is preferably from 95:5 to 20:80, particularly from 90:10 to 20:80, by weight of the chlorinated polypropylene:ethylene-containing carbonyl ethylene copolymer, preferably from 90:10 to 20:80. If there is a large amount of chlorinated polypropylene, the initial adhesion due to the ethylene-carbonylethylene copolymer will be weakened during thermal bonding, making it difficult to obtain sufficient and reliable adhesion using only the heat of the container wall that is being formed. In addition, the wettability of the adhesive decreases, leaving behind sticky lines. Furthermore, if the amount of chlorinated polypropylene is less than the above range, secondary adhesion due to chlorinated polypropylene will decrease, making it impossible to obtain sufficient adhesion.

This blend contains aromatic hydrocarbons such as toluene,
Ethylbenzene, xylene: halogenated hydrocarbons, such as trichlorethylene, tetrachloroethylene, methylchloroform: soluble in alicyclic hydrocarbons, such as cyclohexane, methylcyclohexane, ethylcyclohexane, etc., and applied in the form of this solution, By drying, a film is formed on the adhesive layer.

This Punshindo product is 15g/100rall in toluene.
It is preferred that the adhesive layer has a viscosity of 0.1 to 200 poise, especially 1 to 50 poise, as measured at a temperature of 25°C at a concentration of
In particular, it is preferably in the range of 1 to 10 μm.

The adhesive layer used in the present invention can contain various additives such as tackifiers, heat stabilizers, lubricants, plasticizers, and fillers. As the tackifier, rosin resin, terpene resin, petroleum resin, styrene resin, coumaron-indene resin, etc. can be used.

As the heat stabilizer, a metal soap stabilizer or an organic tin stabilizer is used. Epoxy-based lubricants, wax-based lubricants, etc. are used as the lubricant, dioctyl phthalate, fatty acid mono- or diglyceride, etc. are used as the plasticizer, and inorganic or polymeric microbeads are used as the filler.

In the present invention, the plastics constituting the base film of the label include, for example, crystalline voriprohycine, crystalline propylene-ethylene copolymer, crystalline polybutene-
1. Polyolefins such as crystalline poly-4-methylpentene-1, low-1 medium- or high-density polyethylene; aromatic vinyl polymers such as polystyrene, styrene-butadiene copolymer; polyvinyl chloride, vinylidene chloride resin, etc. halogenated vinyl polymers: nitrile polymers such as acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer; nylon 6, nylon 6.
6. Polyamides such as para- or metaxylylene adipamide: Polyesters such as polyethylene terephthalate and polytetramethylene terephthalate: FFFI polycarbonates: Thermoplastic resins such as polyacetals such as polyoxymethylene.

This stretched film has -1) 19 to 20 to 300 μm
In particular, it is preferable to have a thickness of 50 to 150 um.

As the metal layer, a foil or vapor deposited layer of a metal with metallic luster, such as aluminum, tin, or copper, is used. As a foil,
-M of 1 to 15 .mu.m, especially 5 to 9 .mu.m, is used, while in the case of a vapor deposited layer, a thickness of less than the thickness of the box is used.

For laminating printed stretched film substrates and metal foils, or laminated printed stretched film substrates and metallized films, urethane adhesives, epoxy adhesives, or acid-modified olefin resin adhesives may be used depending on the film substrate. It can be done using

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

When a blend adhesive layer is provided on the printing ink layer, the printing ink contains a chlorinated polypropylene resin, a polyester urethane resin, a polyvinyl urethane resin, or a polyvinyl chloride urethane resin as a binder. This provides good adhesion between both layers.

In FIG. 6 for explaining the operation of the label inside the manufacturing process, in step A, prior to the blow molding of the plastic parison, the blow split molds 7a and 7b are in an open state, and at least A label 1 is previously applied to one cavity surface 8. That is, the cavity surface 8 has a portion that supports the label 1, and this portion is provided with a vacuum suction mechanism 9, and the label 1 is held on the cavity surface 8 by suction. In this case, the label is positioned such that the plastic film base 2 is on the outside and the hot melt adhesive resin layer 5 is on the inside. The application and fixing of the label l to the cavity surface 8 is not limited to suction, but can be
For example, static electricity can also be used.

Next, in step B, the molten plastic parison 1) is extruded from the die IO, the blow molds 7a and 7b are closed, and pressurized gas is blown into the closed parison 1).

In step C, the parison expanding 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, forming the labeled container 12. In addition to the direct blow molding method using a horizontal rotary blow molding machine or vertical rotary blow molding machine, 6-plow molding can also be performed using any blow molding method such as injection blow, two-stage blow molding, sheet forming, stretch blow molding, etc. This can be done using a molding method.

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

As polyolefin plastics constituting the container, those exemplified for films are widely used.

This container can have a single layer or multilayer structure. For example, a container made of a single layer of polyolefin, or a multilayer container made of polyolefin as an inner and outer layer and a thermoplastic resin with a gas barrier provided as an intermediate layer between them. Examples include containers.

As a gas barrier resin, an ethylene-vinyl alcohol copolymer having an ethylene content of 50 to 20 mol%:
Xylylene group-containing polyamides; gas barrier polyesters; high nitrile group-containing polymers; gas barrier resins known per se such as vinylidene chloride resins can be used.

If there is no adhesion between the inner and outer layers and the intermediate layer, acid-modified olefin resins, various copolyamides,
Adhesive resins such as various copolyesters may be included.

(Effect of the invention) According to the present invention, by using a blend of chlorinated polypropylene and a copolymer of ethylene and a carbonyl ethylene-containing monomer as an adhesive for in-mold label attachment, Excellent adhesion is achieved for polyolefin plastic containers molded with, and the bond formed is excellent.

It has the advantage of exhibiting excellent chemical resistance even when it comes in contact with cosmetics, toiletries, and various chemicals.

(Example) The invention is illustrated by the following example.

Example 1 One side of a stretched polypropylene film with a thickness of 100 μm was printed with ink using polyester urethane as a binder, and then a polyester urethane medium was applied on top of that, and a chlorine content of 26 weight%
Chlorinated polypropylene A has a crystal melting peak temperature of 90°C, a crystal melting heat of 2.2 caρ/g, a chlorine content of 35% by weight, and a crystal melting peak temperature of 62°C.
1 Chlorinated polypropylene B with a heat of fusion of 0.8 caβ/g and an ethylene-vinyl acetate copolymer with an MI of 80 and a vinyl acetate content of 43% were mixed in a ratio of 50:25:25.
An adhesive layer was formed by applying a blend at a ratio of 1.5 μm to a film thickness of 1.5 μm.

Next, a square label measuring 90 mm in length and 60 mm in width was punched out from the obtained label base material, and was attached to the surface of a bottle made of ethylene-propylene copolymer having a melting point of 158 DEG C. by the process shown in FIG. In this case, the molten resin temperature of the ethylene-propylene copolymer parison is 210'C.
, the blow mold temperature was 7°C.

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

Also, the adhesive strength between the label and the bottle was measured. (A 90' bill test was performed at a peeling speed of 300 mm/min.) Next, to test the adhesion of the label due to the adhesion of the contents, the in-mold label bottle was soaked in rinse and shampoo at 40°C for 24 hours. did.

As a result, there was no abnormality in the appearance of the labels for any of the contents. Adhesive strength is also HD=500 in the case of rinsing.
g/15mm width, for shampoo HD...530
g/15mm width, which hardly decreased. In addition, an in-mold label bottle was filled with water, left at 5°C for one day, and then the bottle was dropped from a height of 1.2 m 5 times vertically and horizontally for concrete chlorinated polypropylene and ethylene vinyl acetate copolymer. Labels were made in the same manner as shown in Example 1 using various adhesives with different blend ratios,
In-mold label bottles were molded and the appearance and adhesive strength were evaluated. An immersion test was also conducted, and the results are shown in Table 1. The same chlorinated polypropylene and EVA as in Example 1 were used. .

Example A label was made in the same manner as in Example 1 except that the molded bottle material was HDPH with a melting point of 131'C, an in-mold label bottle was molded, and the appearance, Table 1 shows the results of evaluating the adhesive strength and performing a dipping test.

Figure 1.2.3.4 shows an example of the cross-sectional structure of the label of the present invention, Figure 5 shows the DSC curve of chlorinated polypropylene, and Figure 6 shows the in-mold label operation. FIG.

The subtraction number 1 is the label, 2 is the plastic film 23 is the printing ink layer, 4 is the chlorinated polypropylene adhesive layer, 5
5a 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, IO is a die, 1) is a parison, and 12 is a container with a label.

Claims (3)

[Claims] (1) A label that is attached to the outer surface of a polyolefin plastic container by in-mold label attachment, in which a combination of chlorinated polypropylene and ethylene and carbonyl ethylene-containing monomers is attached to the attachment surface of the label base material. A label comprising a polymer blend as an adhesive layer. (2) A polyurethane resin layer or an ink layer using a polyurethane resin as a binder between the label base material and the adhesive layer of a blend of chlorinated polypropylene and a copolymer of ethylene and a carbonyl ethylene-containing monomer. 2. The label according to claim 1, wherein one or both of these are provided. (3) Consisting of a polyolefin plastic container and a label affixed to the outer surface of the container, the label consists of a label base material and chlorinated polypropylene and ethylene and carbonyl ethylene-containing monomers provided on the surface of the label base material. an adhesive layer of a copolymer blend of the following, wherein the label is bonded to the outer surface of the container by in-mold labeling.