JPH11198155A - Label for in-mold molding and production of in-mold molded article using label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a label for in-mold molding good not only in the adhesiveness with a molded article (especially, a cup container by in-mold beads foam molding) but also in the adhesiveness with the outer surface of a base material sheet in an overlapped part at a time of body winding, achieved in cost reduction and capable of effectively suppressing the deposition of contaminant on a mold based on the flow of the printing layer or hot-melt resin layer of the label at the time of molding, and a method for producing an in-mold molded article using the label. SOLUTION: A label 1 is provided on the outer peripheral surface of a molded article simultaneously with the molding of the molded article in a body winding state so that the start end edge and terminal edge of the label generate an overlapped part on the outer peripheral surface of the molded article. This label 1 has such a structure that a solid printing layer 12 is directly provided on the entire surface of the single surface of a base material sheet 11 through a patternwise printing layer 12' and a hot-melt resin layer 13 is provided on the end edge part becoming the overlapped part on a printing layer 12 and the printing layers 12, 12' are constituted of a printing layers of backing printing grade laminate ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a label for in-mold molding, that is, a label to be formed on a peripheral surface of a molded article at the same time as molding a molded article having a cylindrical portion. The present invention also relates to a method for producing an in-mold molded article having the label on the outer peripheral surface.

[0002]

[Prior Art] <Layer structure of label for in-mold molding>
A label for in-mold molding to be provided on the outer peripheral surface of a hollow body or another molded article at the same time as molding of the molded article is basically a base sheet / printed layer / heat-fusible resin layer (adhesive layer) Having the following layer configuration.

[0003] As for the label for in-mold molding, there have been various applications focusing on the type of each layer and the physical properties of the label. For example, JP-A-58-69015 (label having a paper-like layer of a stretched polypropylene film), JP-A-2-217223 (specifying the shrinkage of the label), and JP-A-3-153334 (molding of bottles) Using a label that matches the heat shrinkage at the time),
JP-A-244189 (using an unstretched plastic base film, embossing is also possible on the adhesive coating layer), JP-A-2-267584 (specifying the heat shrinkage of the substrate), and JP-A-5-333785 (An in-mold label consisting of a two-layer laminate composed of a co-extruded skin layer and a foam layer and a printing surface provided on the surface of the skin layer). In addition, the following applications have been filed.

<Point-like installation of adhesive layer>
No. 84, in-mold label in which a heat-sensitive and point-like adhesive is present on the back surface of a label base material adhered to a molded article, and the vertical section of each adhesive has an arc-shaped cross section. It is shown.

<Partial installation of adhesive layer> JP-A-5-4609
Japanese Patent Publication No. 4 (1994) discloses an in-mold label used when integrated with a container at the same time as blow molding, in which a heat seal varnish is provided with a fixed width from the outer edge only on the outer periphery of a substrate made of a plastic film, and Is shown with an in-mold label missing.
When a container with a label is molded using this in-mold label, the label is completely adhered to the container because the heat seal varnish is provided on the outer periphery of the label, and the end of the label can be easily grasped. It is said that it can be peeled off with a weak force, making it suitable for recycling containers.

<Application of In-Mold Molding Label to In-Mold Bead Foam Molding> Molded articles provided with in-mold molding labels are mainly formed by injection molding, hollow molding, differential pressure molding (vacuum molding or air pressure molding). JP-A-4-4130 (a transparent in-mold label that defines the opacity and tensile modulus of a resin film) and JP-A-4-29184 (when the heat-sensitive adhesive resin layer is made of an ethylene-based resin). (A resin containing a plasticizer) is described as being applicable to in-mold bead foam molding. However, in any case, there is no example concerning the in-mold bead foam molding.

In addition, JP-A-4-4121 (a transparent in-mold label defining the thickness, opacity, and Clark stiffness of a resin film), and JP-A-5-80702
Japanese Patent Application Laid-Open No. 5-205, in which a lubricant selected from fatty acid amides or fatty acid metal salts is blended in the resin constituting the adhesive layer.
No. 249895 (an adhesive layer is formed on a substrate obtained by embossing a resin film and further stretching the surface to form an embossed pattern) is described in the description of the conventional method. Reference is made to bead foam molding.

<Cup container by in-mold bead foam molding>
Cup containers made of polystyrene foam beads or bead foam molding in a foaming mold using the pre-foamed foam are manufactured in large quantities for filling instant noodles, but because the container wall is made of a fused body of bead foam. Since it is porous, the permeability of moisture and air cannot be reduced below a certain limit as it is, and there is a problem in the storage stability of the contents. Therefore, after forming the cup container, the container is dipped in an emulsion of polyvinylidene chloride having excellent moisture resistance and gas permeability and dried to form a coating.

[0009]

A cup container made of polystyrene bead foam is particularly suitable for filling instant noodles because of its light weight and heat insulation, but the rough surface of bead foam is exposed on the surface. Therefore, there is room for improvement in the external appearance, and there is a problem in the storage stability of the contents as described above as it is because the container wall is made of a fused body of bead foam. In this case, if an in-mold molding label can be attached to the outer peripheral surface of the cup container, the appearance becomes significantly more beautiful, and the moisture resistance and gas permeability resistance can be obtained without providing a coating with an emulsion of polyvinylidene chloride. Will be secured.

In general, an in-mold molding label has a layer structure of a base sheet / printing layer / heat-fusible resin layer as described above, and the heat-fusible resin layer is provided on the entire surface of the label. When the outer peripheral surface of the molded product is provided so as to form an overlap between the start edge and the end edge of the label on the outer peripheral surface of the molded product, the heat-fusible resin layer has not only the adhesive property with the molded product but also the overlap of the label. In the part, adhesion to the outer surface of the base sheet is also required.

Particularly, when the label for in-mold molding is applied to in-mold bead foam molding, typically, the molded product is a tapered cup container made of a polystyrene bead foam molded product, and the base sheet is a biaxial foam. In the case of stretched polypropylene film (OPP), the heat-fusible resin layer must be well adhered to the polystyrene bead foam molded article, and also well adhered to the outer surface of the biaxially stretched polypropylene film at the overlapping part when the body is wound. Have to do it. However, it is not easy for the heat-fusible resin layer to simultaneously satisfy both adhesiveness. If the adhesiveness with the polystyrene bead foam is insufficient, the label may slip off from the cup container during the distribution process.On the other hand, if the adhesiveness with the outer surface of the biaxially oriented polypropylene film is insufficient, the overlapping portion is peeled off. The appearance may be reduced, and the commercial value may be impaired.

The amount of food produced by filling instant noodles in a cup container made of expanded polystyrene beads is enormous, and the cup container is molded in an instant noodle manufacturing plant.
It is used immediately in the filling line of instant noodles, but if any trouble occurs in the cup container provided with the label for in-mold molding, the entire production line of instant noodles with cups stops, and it places a great burden on the inspection process. Will be.

[0013] In addition, since instant noodles in cups are low-margin products, the cost of the label for in-mold molding directly relates to the product cost. Accordingly, the cost of the heat-fusible resin layer constituting the label (which is usually provided over the entire surface of the wide base material sheet or over the area of the label) is also minimized. Is required.

The method of providing a heat seal varnish with a constant width from the outer edge only on the outer periphery of the base film as described in JP-A-5-46094 is suitable for a special purpose on the premise of peeling. However, since the adhesiveness of the label to the molded product is essentially poor, it is impossible to apply the method to bead-in-mold molding.

Under such a background, the present invention not only has an adhesive property with a molded product (especially, a cup container formed by in-mold bead foam molding), but also has an advantage in that the outer surface of the base material sheet at the overlapping portion when the body is wound is formed. Good adhesion, and cost reduction, and effectively suppresses the accumulation of dirt on the mold due to the flow of the label printing layer and the heat-fusible resin layer during in-mold molding. It is an object of the present invention to provide a label for in-mold molding that can be used, and a method for producing an in-mold molded article using the label.

[0016]

According to the label for in-mold molding of the present invention, at least a cylindrical molded article (2) having a cylindrical body is formed, and at the same time, the starting edge of the label is formed on the outer peripheral surface of the molded article (2). A label (1) for providing a body winding so that an overlapping portion (m) is formed between the label and the terminal edge, wherein the label (1) is
A solid printing layer (12) is provided directly or via a patterned printing layer (12 ') on the entire surface of one side of the base sheet (11),
And a structure in which a heat-fusible resin layer (13) is provided on an edge portion of the printing layer (12) which becomes the overlapping portion (m), and the printing layers (12 '), (12 ) Is a printed layer of a back-print grade laminate ink having adhesiveness to the molded article (2) at the time of molding the molded article (2).

The method for producing an in-mold molded article of the present invention comprises:
The label (1) according to claim 1 is supplied into a mold such that the start edge and the end edge of the label form an overlapping portion (m), and at least the body has a cylindrical shape according to the mold. (2) is molded, and simultaneously with the molding of the molded product (2), the label (1) is placed on the outer peripheral surface of the molded product (2) in the shape of a trunk.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

According to the label for in-mold molding of the present invention, a molded article (2) having a cylindrical body at least is formed at the same time as molding.
The label (1) is provided in a body-wound form so that the start edge and the end edge of the label form an overlapping portion (m) on the outer peripheral surface of the molded product (2). The cylindrical shape includes a cylindrical shape, an elliptical cylindrical shape, a rectangular cylindrical shape, a conical cylindrical shape, a cup shape, and the like.

Examples of such a molded article (2) include molded articles obtained by injection molding, hollow molding, vacuum molding, air pressure molding and the like. In the mold, foamable beads or a prefoamed product thereof are foamed in a mold. Particularly important is a molded product obtained by bead foam molding.

Here, the expandable beads or the prefoamed body thereof may be polystyrene beads, polyethylene beads, polypropylene beads, polymethyl methacrylate beads, polyvinylidene chloride beads, polyacrylonitrile beads, etc. Foams.

Particularly important among the molded articles (2) formed by in-mold bead foam molding are cup containers using expandable polystyrene beads or a prefoamed body thereof.
The label (1) is provided on the entire outer peripheral surface of the cup container.

In the present invention, as the label (1), a solid print layer (12) is provided directly on the entire surface of one side of the base sheet (11) or via a pattern print layer (12 '). And a structure in which a heat-fusible resin layer (13) is provided on an edge portion of the printing layer (12) which becomes the overlapping portion (m).

As the base sheet (11), biaxially oriented polypropylene film (OPP), biaxially oriented polyester film (PET), biaxially oriented nylon film (ON
Y), various synthetic resin films including unstretched polypropylene film (CPP), unstretched nylon film, stretched or unstretched polystyrene film, stretched or unstretched ethylene-vinyl alcohol copolymer film, and polyvinyl chloride film. Used. In some cases, paper can be used, but when moisture resistance or gas permeability resistance is required, it is preferable to use a resin processed product. When applied to in-mold bead foam molding, biaxially oriented polypropylene film is particularly important, and biaxially oriented polyester film is also important in consideration of cost, physical properties, and the like.

On one side of the base sheet (11), a patterned printing layer (12 ') is provided first, and then on one side of the base sheet (11) from above the patterned printing layer (12'). A solid printing layer (12) is provided on the entire surface. The patterned printing layer (12 ')
It may be omitted in some cases. Printing layer (12 '),
When (12) is provided, the base film (11) may be subjected to corona discharge treatment or anchor coating treatment in advance. It should be noted that a patterned printing layer may be provided on the opposite surface of the base film (11).

The printing layers (12 ') and (12) are formed by gravure printing,
Although it is provided by an offset printing method, a flexographic printing method, a screen printing method, or the like, it is particularly desirable to provide the gravure printing method in consideration of productivity and beauty.

Since the printed layers (12 ') and (12) are in direct contact with the molded product (2), they are required to have an adhesive property with the molten or softened product of the molded product (2). Therefore, in the present invention, the printing layers (12 ′) and (12) are formed of a printing layer of a backing grade laminate ink having adhesiveness to the molded product (2) when the molded product (2) is molded. Constitute.

At this time, the printing layer of the backing-grade laminate ink constituting the printing layers (12 ') and (12)
In the molding of (2), a layer of a composition in which a pigment and / or a curing agent is blended with a binder resin so that the adhesiveness to the molded article (2) is ensured and the flow rate is suppressed. It is particularly preferred that it consists of With such a quantitative ratio, the printing layers (12 ') and (12) do not normally have tackiness and blocking is prevented.

The binder resin varies depending on the material of the molded article (2), and includes, for example, urethane resin, acrylic resin, polyester resin, alkyd resin, and the like.
Polyamide-based resins, maleic acid resins, chlorinated polypropylenes, chlorinated polyethylenes, polyvinyl chloride-vinyl acetate copolymers, nitrified cotton, chlorinated rubbers, rosin-modified resins, and mixtures thereof are used. In some cases, an active energy ray-curable resin may be used. Molding
When (2) is a cup container formed by in-mold bead foaming using expandable polystyrene beads or its pre-foam, urethane resin, urethane resin / vinyl chloride (vinyl chloride-vinyl acetate copolymer) And chlorinated polypropylene.

As pigments, white, red, red, yellow, blue, indigo,
Inorganic pigments of any hue such as black, silver, and pearl are used, and organic pigments can also be used. Solid printing layer (1
In the case of 2), a white pigment (particularly titanium oxide having a large hiding power) such as titanium oxide, calcium carbonate, zinc oxide, barium sulfate, lithopone, silica, and basic lead carbonate is often used.

Depending on the functional group of the binder resin, various curing agents such as polyisocyanate, epoxy, melamine, amine, phenol, aldehyde, organometallic and metal ion can be used. Agent is used.

The mixing ratio of the pigment and / or the curing agent to the binder resin is, as described above,
At the time of molding (2), it is set so that the adhesiveness to the molded article (2) is ensured and the flow rate is controlled so that an inorganic pigment is mixed with the binder resin as an example. And an inorganic pigment in an amount of 1 to 1 part by weight of the binder resin.
7 parts by weight (particularly 2 to 5 parts by weight) is often used. In the case of a hardener, the hardener is added in an amount of 0.001 to 1 part by weight of the binder resin according to the combination of the binder resin and the hardener.
It is selected from a wide range such as 1 part by weight.

The backing grade laminating ink for the printing layers (12 '), (12), besides the binder resin, pigment or / and curing agent, usually has an appropriate amount to give a viscosity suitable for printing. Is used. As the solvent, an aqueous solvent can be used in addition to the organic solvent. In some cases, printing is performed without using a solvent, without using a solvent, or in a molten state. If necessary, the ink may contain additives such as auxiliary agents (plasticizer, wax, lubricant, defoamer, chelating agent, antistatic agent, surfactant, coupling agent, thixotropic agent, etc.) can do.

Next, the heat-fusible resin layer (13) is provided on the solid printed layer (12) at the edge portion serving as the overlapping portion (m).
It is provided by a printing method as described above, in particular a gravure printing method.

Preferred resins for forming the heat-fusible resin layer (13) are ethylene-vinyl acetate copolymer, acrylic copolymer and the like. The layer (13) is formed of an emulsion or a solution of these resins. It is formed by using.

The in-mold molded product can be obtained from the above label (1)
The start and end edges of the label overlap in the mold.
(m) is supplied to produce a molded product (2) having at least a cylindrical body (particularly a cup container formed by in-mold bead foam molding) according to the mold, and the molded product (2 ) At the same time as the molding of the molded article (2).
(1) should be installed.

When the molded product (2) is a cup container formed by in-mold bead foam molding using expandable polystyrene beads or its pre-foamed material, the molding temperature may be from about 120 ° C. to about 140 ° C. Many.

[0038]

The present invention will be further described with reference to the following examples. Hereinafter, “parts” and “%” are shown on a weight basis.

Example 1 FIG. 1 is an explanatory view showing an example of a manufacturing process of a label for in-mold molding according to the present invention. FIG. 2 is a rear view of the label for in-mold molding of the present invention. FIG. 3 shows the label X in FIG.
FIG. 4 is a cross-sectional view of −X, in which the layer thickness is exaggerated. FIG. 4 is a perspective view of an in-mold molded product manufactured using the label of FIG.

By performing corona discharge treatment on one side of a base film (11) made of a biaxially oriented polypropylene film (OPP) having a thickness of 40 μm and performing multicolor gravure printing using a coloring ink, predetermined characters, A 1 μm printed layer (12 ′) having a patterned pattern was formed. Subsequently, gravure printing is performed from above using a white ink, so that a 1 μm white solid over the entire label area is obtained.
m of the printed layer (12) was formed.

As the ink for forming the printing layer (12 '), two kinds of inks composed of 10% of a polyurethane binder, 30% of a pigment (red for the first color and yellow for the second color) and 60% of a solvent were used. Using.

As the ink for forming the printing layer (12),
Main ingredient 100 consisting of 10% urethane prepolymer binder, 30% white pigment (titanium oxide), and 60% solvent
A two-pack type ink in which 3 parts of a polyisocyanate-based curing agent was blended in one part was used.

Then, from the top of the printing layer (12) on the base film (11), only the edge portion serving as the overlapping portion (m) was coated with a solid content of 25% of an ethylene-vinyl acetate copolymer emulsion diluted with water. By performing gravure printing using a% heat sealant, a 1.5 μm-thick heat-fusible resin layer (13) was formed in a strip shape.

After the printing is completed in this way, punching is performed along the contour of the white solid printing layer (12), and the individual labels are printed.
(1)

The label (1) is supplied into a mold so that the start edge and the end edge of the label form an overlap (m),
Then, a cup container for instant noodles as an example of the molded product (2) is formed by in-mold bead foaming (steam heating: 130 ° C.) using expandable polystyrene beads (preliminary foam) according to the mold. did.

In the obtained in-mold molded body,
The label (1) adhered well to the entire outer peripheral surface of the cup container, and the adhesiveness with the outer surface of the base film at the overlapping portion (m) when the body was wound was also preferable. 200
During the continuous running of time, there were no failures. During that period, stains on the mold due to exudation of the printing layers (12 ′) and (12) and the heat-fusible resin layer (13) were practically not observed.

Example 2 A two-pack type ink in which 4.5 parts of a polyisocyanate-based curing agent was blended with 100 parts of a base material composed of 15% of a urethane prepolymer-based binder and 85% of a solvent as an ink for forming a printing layer (12). Example 1 was repeated except that the ink (medium) was used. In this case, the same preferable results as in Example 1 were obtained.

[0048]

According to the label for in-mold molding of the present invention,
In order to form a molded article (2) with at least a body part at the same time as a cylinder, at the same time as forming the body part (m) so that the start and end edges of the label overlap each other on the outer peripheral surface of the molded article (2). It is the label (1), and the following measures are taken. A solid print layer (12) is provided directly on the entire surface of one side of the base sheet (11) or via a pattern print layer (12 '). A heat-fusible resin layer (13) is provided on an edge portion of the printing layer (12) to be the overlapping portion (m). The printed layers (12 ′) and (12) are printed layers of a back-printing-grade laminated ink having adhesiveness to the molded product (2) when the molded product (2) is molded.

As described above, the printing layers (12 ') and (12) are formed of a backing grade laminating ink having specific properties, and the laminating ink at that time is preferably a pigment in a binder resin. And / or the use of a composition containing a curing agent ensures adhesion to the molded product (2) when molded with the molded product (2) (especially a cup container formed by in-mold bead foam molding). Above, when using a compound containing a pigment, the flow is also suppressed by heat during in-mold molding, and when using a compound containing a curing agent, a network structure is formed by the reaction with the binder resin. The flow during molding is suppressed, and as a result, the printed layer (12 '), (1
2) It is possible to effectively prevent the flow of the layer and the accumulation of dirt on the mold. In addition, the printing layers (12 ') and (12) are not tacky under normal conditions, and blocking is prevented.

Then, as described above, the heat-fusible resin layer (1) is formed only on the edge portion on the printing layer (12) which is the above-mentioned overlapping portion (m).
Since 3) is provided, the overlapping part (m) when the body is wound
The adhesiveness to the outer surface of the base sheet (11) is also ensured. In addition, since the heat-fusible resin layer (13) is provided only on the edge portion that becomes the overlapping portion (m) (since it is enough to cover only a small area of the label (1)), The amount used is extremely small compared to the amount of the conventional heat-sealable adhesive layer, and as a result, the heat-fusible resin layer (1
The accumulation of dirt on the mold due to the flow of 3) is effectively suppressed, and the amount of resin is small, so that the cost can be surely reduced. Also, since the heat-fusible resin layer (13) may be selected mainly from the viewpoint of adhesiveness to the outer surface of the base film (11), a resin suitable for this purpose can be easily selected.

When the label for in-mold molding is applied to a cup container formed by in-mold bead foam molding using expandable polystyrene beads or its pre-foamed body, the appearance becomes remarkably beautiful. Moisture resistance, gas permeation resistance, and aroma retention can be secured without providing an emulsion coating.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a production process of a label for in-mold molding of the present invention.

FIG. 2 is a rear view of the label for in-mold molding of the present invention.

FIG. 3 is a cross-sectional view taken along line XX of the label of FIG. 2, in which the layer thickness is exaggerated.

FIG. 4 is a perspective view of an in-mold molded product manufactured using the label of FIG. 2;

[Explanation of symbols]

 (1) ... label, (11) ... substrate sheet, (12 ') ... patterned printing layer, (12) ... solid printing layer, (13) ... heat-fusible resin layer, (2) ... Molded product, (m) ... overlapping part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 105: 04 B29L 9:00 22:00

Claims (4)

[Claims] At least at the same time that a molded article (2) having a cylindrical body is formed at the same time, the start edge and the end edge of the label form an overlapping portion (m) on the outer peripheral surface of the molded article (2). A label (1) to be provided in a torso shape, wherein the label (1) is printed on the entire surface of one side of a base sheet (11) directly or through a printed layer (12 ') in a solid pattern. A layer (12) is provided, and has a structure in which a heat-fusible resin layer (13) is provided on an edge portion serving as the overlapping portion (m) on the printing layer (12),
And wherein the printing layers (12 ′) and (12) are printing layers of a backing-grade laminated ink having adhesiveness to the molded article (2) when the molded article (2) is molded. For in-mold molding. 2. A label for in-mold molding according to claim 1, wherein the molded product (2) is a cup container formed by in-mold bead foam molding, and the label (1) is provided on the entire outer peripheral surface of the cup container. . 3. The printed layer of the backing-grade laminated ink constituting the printed layers (12 ') and (12) ensures the adhesion to the molded product (2) when the molded product (2) is molded. The label for in-mold molding according to claim 1 or 2, comprising a layer of a composition in which a pigment and / or a curing agent is blended with a binder resin such that the flow rate is controlled to a quantitative ratio. . 4. The label (1) according to claim 1 is supplied into a mold so that the start edge and the end edge of the label form an overlapping portion (m), and at least the body portion is fitted to the mold. An in-mold method comprising: molding a cylindrical molded article (2); and simultaneously forming the molded article (2), and placing a label (1) on the outer peripheral surface of the molded article (2). Manufacturing method of molded body.