JP2014224882A - Label for in-mold molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a label for in-mold molding capable of increasing a display area, making the thickness of the label thin, and visually recognizing individual printing display clearly.SOLUTION: A label for in-mold molding includes: a base layer A; a printable layer B; and a heat seal layer C in this order. The opacity of the printable layer B is 60% or less, and the printable layer B has printing information on the surface of the side of the heat seal layer C. The interfacial peeling strength between the base layer A and the printable layer B is 0.4-1.6 N/15 mm.

Description

The present invention relates to an in-mold forming label that can be peeled between layers. Specifically, the present invention relates to an in-mold molding label that includes a base layer (A) and a printable layer (B), and is capable of interfacial peeling between the base layer (A) and the printable layer (B).
In the resin molded product to which the label for in-mold molding is attached, information printed in advance on the printable layer (B) that appears by peeling off the base layer (A) on the outermost surface of the label can be seen. For this reason, the display area of the label for in-mold molding can be increased. In-mold molding labels can be used as coupons, application seals, tamper-proof labels, and the like.

  Conventionally, a blank (a label on which no information is displayed) or a label on which information is displayed (hereinafter referred to as “label” together) is inserted into a mold, and then injection molding, hollow molding, A resin molded product such as a container is formed by molding a resin molded product such as a container in the mold by differential pressure molding, foam molding, or the like (see, for example, Patent Document 1). . Such a label is called an in-mold label, which is a gravure-printed resin film, offset-printed synthetic paper, flexographic-printed synthetic paper, or high-pressure low-density polyethylene, ethylene An aluminum label or the like obtained by laminating a vinyl acetate copolymer and gravure-printed on the surface of the foil is known and put into practical use.

On the other hand, such resin molded products are often used in containers for storing and selling liquid and powdered contents such as detergents and pesticides. Recently, these products have liquid and powder contents. There is a movement to reduce the volume by condensing things, and for buyers to seek ease of handling by reducing weight, and for manufacturers and sellers to reduce transportation costs and manage inventory of goods.
Along with this movement, resin molded products that contain these contents are also becoming smaller, but as the size of the resin molded products decreases, the area of the label that can be attached to the resin molded products also decreases, so it is displayed on the label. It is necessary to make the characters to be smaller or to delete the contents to be displayed. However, there are many pieces of information that can be clearly read and cannot be deleted, such as trademarks and product names for product identification, origin indications, expiry dates, and handling precautions.
Conventional in-mold molding labels mainly use one sheet base material for the purpose of firmly attaching the labels so as not to be peeled off from the resin molded product. Since this label can be printed only on the surface, it has been difficult to sufficiently cope with the problem of reduction in the display area of the label as described above.

Therefore, for the purpose of improving the display area of the in-mold molding label, an in-mold molding label has been proposed in which two or more printed labels can be laminated and peeled off.
For example, Patent Document 2 discloses a container with an in-mold label in which an adhesive is applied to at least a part of a printed label, and a label in which another printed label is laminated thereon is attached to the container. Patent Document 3 discloses a label for in-mold molding in which a plurality of printed resin films are laminated via an ultraviolet curable and / or electron beam curable pseudo-adhesive resin layer that can be peeled off. ing. Patent Document 4 proposes an in-mold molding label that includes a base layer (A) containing a thermoplastic resin, a layer (B) that enables delamination, and a heat seal layer (C) in this order. ing. Here, the label can be peeled off by the layer breakage of the layer (B) itself that enables delamination.

  Patent Document 5 discloses an in-mold label including a printable surface and an adhesive layer. Here, in order to improve recyclability, it has been proposed to remove the printing layer by peeling the label from the separation interface between the printable surface and the adhesive layer to remove the printing ink on the printable surface. .

JP 58-69015 A JP 2001-240066 A JP 2005-91594 A JP 2003-295767 A JP 7-50797A

However, in a conventional label for in-mold molding, after forming a container with an in-mold label, the label floats without catching up with the mold shrinkage of the container, and the appearance of the container tends to deteriorate. In addition, since the label itself becomes thicker as the sheets are overlapped, the container tends to be broken when the container with the in-mold label containing the contents falls.
Further, as in Patent Document 4, in the case of a configuration including a base layer (A) containing a thermoplastic resin, a layer (B) enabling delamination, and a heat seal layer (C) in this order, delamination Since peeling progresses due to cohesive failure in the layer (B) enabling the labeling, the display on the resin molded product after the label peeling is visually recognized through a part of the broken layer (B). For this reason, it is somewhat unclear, the design or the like is not fine, and fine characters and the like tend to be difficult to recognize.
Moreover, in the label for in-mold molding like patent document 5, the film of the surface side containing the adhesive bond layer which remains in the container side at the time of recycling did not have printing information from the request | requirement of recycling.
In other words, in the prior art, when the display area of the label for in-mold molding is increased, the label itself is not sufficiently thinned, and the print information that can be visually recognized after peeling the base layer (surface layer) is clearly recognized. It was difficult to do so and further improvements were sought.

  Accordingly, the present inventors provide an in-mold molding label capable of increasing the display area, the label itself being thin, and the individual printed display clearly visible. We proceeded with the study as an issue.

As a result of earnest studies to solve the above problems, the present inventors, in the in-mold molding label, which includes the base layer (A), the printable layer (B) and the heat seal layer (C) in this order, Printing information is printed on the printable layer (B) whose opacity is a certain value or less, and the interfacial peel strength between the base layer (A) and the printable layer (B) is 0.4 to 1.6 N / 15 mm. Thus, it was found that the thickness of the label can be reduced while increasing the display area. Furthermore, the present inventors have found that each printed display can be clearly recognized by making the in-mold forming label have the above configuration, and have completed the present invention.
Specifically, the present invention has the following configuration.

[1] An in-mold molding label including a base layer (A), a printable layer (B), and a heat seal layer (C) in this order, and the opacity of the printable layer (B) is 60% or less The printable layer (B) has printing information on the surface on the heat seal layer (C) side, and an interfacial peel strength between the base layer (A) and the printable layer (B) is 0.4 to 0.4. An in-mold forming label characterized by being 1.6 N / 15 mm.
[2] The in-mold molding label according to [1], wherein an adhesive strength between the printable layer (B) and the heat seal layer (C) exceeds 1.6 N / 15 mm.
[3] The in-mold molding label according to [1] or [2], wherein the tensile strength of the base layer (A) and the printable layer (B) exceeds 1.6 N / 15 mm, respectively. .
[4] The base layer (A) includes at least one thermoplastic resin (a) selected from the group consisting of an olefin resin, a styrene resin, an ester resin, an amide resin, and a polycarbonate. The label for in-mold molding according to any one of [1] to [3].
[5] The printable layer (B) includes at least one thermoplastic resin (b) selected from the group consisting of an olefin resin, a styrene resin, an ester resin, an amide resin, and a polycarbonate,
The in-mold molding label according to [4], wherein the thermoplastic resin (a) and the thermoplastic resin (b) are different thermoplastic resins.
[6] The in-mold molding according to any one of [1] to [5], wherein the base layer (A) includes an olefin resin, and the printable layer (B) includes a styrene resin. For labels.
[7] The in-mold according to any one of [1] to [6], wherein the base layer (A) or the printable layer (B) includes at least one of a compatibilizing agent and a release agent. Label for molding.
[8] The base layer (A) and the printable layer (B) are laminated by any one of coextrusion molding, extrusion lamination molding, and heat lamination molding [1] to [7] The label for in-mold shaping | molding in any one of.
[9] The in-mold molding according to any one of [1] to [8], wherein the base layer (A) further has printing information on a surface not in contact with the printable layer (B). label.
[10] The in-mold molding label according to any one of [1] to [9], wherein the opacity of the base layer (A) is 80% or more.
[11] The printable layer (B) and the heat seal layer (C) have a half cut line, and the half cut line extends from the heat seal layer (C) surface side to the printable layer (B). And the base layer (A), the in-mold molding label according to any one of [1] to [10], which is provided in series in a direction perpendicular to the surface direction. .
[12] The in-mold molding label according to any one of [1] to [11], wherein a paste-killing portion is provided on a part of the surface of the heat seal layer (C).
[13] A resin-molded article with a label in which the label for in-mold molding according to any one of [1] to [12] is attached to a resin-molded article by in-mold molding and integrated.
[14] The labeled resin molded product according to [13], wherein the resin molded product includes at least one thermoplastic resin selected from an olefin resin, a polystyrene resin, and a polyethylene terephthalate resin.
[15] The adhesive strength between the in-mold molding label according to any one of [1] to [12] and the resin molded product exceeds 3.0 N / 15 mm [13] or [14] ] The resin molded product with a label as described in.
[16] When peeling the in-mold molding label from the resin-molded article with the label, peeling progresses at the interface between the base layer (A) and the printable layer (B), and the in-mold molding label is peeled off The resin-molded article with a label according to any one of [13] to [15], wherein a printable layer (B) having a printing information and a heat seal layer (C) remain on the resin-molded article.

The label for in-mold molding of the present invention can provide a printed display on each surface of the base layer (A) and the printable layer (B), and can double the display area. In the in-mold molding label of the present invention, the base layer (A) and the printable layer (B) are laminated in such a manner that the interface can be peeled by hand. When the base layer (A) is peeled off, printing can be performed in advance from there. It becomes possible to visually recognize the print information provided in the layer (B). Thus, the in-mold label of the present invention clearly shows not only the printing information provided on the base layer (A) but also the printing information provided on the printable layer (B) after the base layer (A) is peeled off. Can be visually recognized.
Further, since the in-mold molding label of the present invention is thinned, the appearance of the label is not deteriorated when a resin molded product with a label is molded using the label.

  Furthermore, in the in-mold molding label of the present invention, it is difficult to re-attach the base layer (A) onto the printable layer (B) after the base layer (A) is peeled off. And prevention of reuse. Further, the base layer (A) peeled off from the in-mold molding label of the present invention can also be used for coupons, application tickets, etc., and the print information on the printable layer (B) is only available to the product purchaser. It is also possible to use print information that can be used (for example, a code number for a prize, a QR code (registered trademark), a lottery, a fortune-telling, etc.).

It is sectional drawing of the uniform state of the label for in-mold shaping | molding of this invention. It is sectional drawing which shows the state from which the label for in-mold shaping | molding of FIG. It is sectional drawing which shows the state which gave the paste part and the half cut to the label for in-mold shaping | molding of FIG. It is sectional drawing which shows the state which grasps and peels the paste killing part of the label for in-mold shaping | molding of FIG.

Hereinafter, the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not limited to these contents.
In addition, when it describes with "-" in this invention, it points out the range which includes the numerical value described before and behind that as a minimum value and a maximum value, respectively.
In the present invention, the expression “(meth) acrylic acid” includes both acrylic acid and methacrylic acid.
In the present invention, the term “main component” refers to the component having the highest content on a mass basis among the components contained in the target composition.

[Configuration and physical properties of in-mold molding labels]
The label for in-mold molding of the present invention includes a base layer (A), a printable layer (B), and a heat seal layer (C). As shown in FIG. 1, the in-mold molding label 10 is formed by laminating a base layer (A) 1, a printable layer (B) 2, and a heat seal layer (C) 3 in this order. . As shown in FIG. 2, in the in-mold molding label 10 of the present invention, peeling is possible at the interface between the base layer (A) 1 and the printable layer (B) 2.
The in-mold molding label 10 may be one in which the base layer (A) 1, the printable layer (B) 2, and the heat seal layer (C) 3 are laminated adjacently in this order. You may have another layer on the surface.

In the same label, the interfacial peel strength between the base layer (A) and the printable layer (B) is 0.4 to 1.6 N / 15 mm, matching the mold shrinkage of the molded product when molding a resin molded product with a label. Both are bonded to such an extent that the base layer (A) and the printable layer (B) can follow and deform, but are bonded to such an extent that they can be peeled off by hand.
Printing on the label can usually be performed on the base layer (A). In the present invention, the print information is provided on the surface of the printable layer (B) on the heat seal layer (C) side. After the base layer (A) is peeled off, the printable layer (B) The print information (information such as patterns and characters) provided on the printable layer (B) can be visually recognized through the. At this time, the opacity of the printable layer (B) is 60% or less in order to clarify the display of the print information.

  The thickness of the entire label is preferably 21 μm or more, and more preferably 50 μm or more, from the viewpoint of heat insulation so that heat received from the molten resin does not escape to the mold. On the other hand, if the stiffness is too high, the base layer (A) and the printable layer (B) tend to be peeled off during normal transportation and use, so 160 μm or less is preferable, and 140 μm or less is more preferable.

[Base layer (A)]
The base layer (A) is the outermost layer in the in-mold label. The base layer (A) is preferably a film containing a thermoplastic resin.

(Thermoplastic resin)
The type of the thermoplastic resin used for the base layer (A) is not particularly limited. For example, high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, propylene-based copolymer resin, polymethyl-1-pentene, ethylene / cyclic olefin copolymer and other olefin-based resins capable of film forming; atactic polystyrene, Styrene resins such as syndiotactic polystyrene and styrene-maleic acid copolymer; polyethylene terephthalate, polyethylene terephthalate isophthalate, polybutylene terephthalate, and ester resins such as polybutylene succinate, polybutylene adipate, polylactic acid; ethylene Functional group-containing polyolefin resin such as vinyl acetate copolymer, ethylene / acrylic acid copolymer, maleic acid modified polyethylene, maleic acid modified polypropylene; nylon-6, na Include and polycarbonate; amide resins such as Ron 6,6. Among these resins, one kind or a mixture of two or more kinds can be used.
Among these thermoplastic resins, from the viewpoint of excellent film processability, an olefin resin or a functional group-containing olefin resin is preferable, and an olefin resin is more preferable.

More specifically, the olefin-based resin is composed solely of olefin monomers such as ethylene, propylene, butylene, pentene, hexene, octene, butadiene, isoprene, chloroprene, methyl-1-pentene, and cyclic olefin. Examples thereof include a copolymer and a copolymer composed of two or more of the olefin monomers.
More specifically, examples of the functional group-containing olefin resin include a copolymer of at least one olefin monomer and at least one monomer copolymerizable with the olefin monomer.

  Examples of monomers copolymerizable with the olefin monomers include styrenes such as styrene and α-methylstyrene; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl laurate, vinyl stearate, Carboxylic acid vinyl esters such as vinyl benzoate, vinyl butylbenzoate, and vinyl cyclohexanecarboxylate; unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid, maleic anhydride, and acid anhydrides thereof; Methyl) methacrylate, ethyl (meth) acrylate, butyl (meth) acrylate, glycidyl (meth) acrylate, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl ester, itaconic acid Monomethyl ester, Unsaturated carboxylic acid esters such as taconic acid diethyl ester; (meth) acrylamide, maleic acid monoamide, maleic acid diamide, maleic acid-N-monoethylamide, maleic acid-N, N′-diethylamide, maleic acid-N— Monobutylamide, maleic acid-N, N′-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monoethylamide, fumaric acid-N, N′-diethylamide, fumaric acid-N-monobutylamide , Fumaric acid-N, N′-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide and other unsaturated carboxylic acid amides; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, benzyl vinyl ether And vinyl ethers such as phenyl vinyl ether.

  The functional group-containing olefin resin is hydrolyzed with an acid or a base, and the functional group derived from the carboxylic acid vinyl ester, the unsaturated carboxylic acid, the unsaturated carboxylic acid ester, or the unsaturated carboxylic acid amide is converted into a hydroxyl group or a carboxylic acid. It may be converted to an acid or carboxylic acid metal salt.

Further, the olefin resin or the functional group-containing olefin resin can be graft-modified. Examples of the graft modification include a method of reacting a peracid such as peracetic acid, persulfuric acid, potassium persulfate and the like and a metal salt thereof; an unsaturated carboxylic acid or a derivative thereof in the presence of an oxidizing agent such as ozone.
Graft modification rate is 0.005-10 mass% normally with respect to olefin resin or a functional group containing olefin resin, Preferably it is 0.01-5 mass%.

Examples of the unsaturated carboxylic acid used for graft modification include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid.
Examples of the unsaturated carboxylic acid derivative used for graft modification include acid anhydrides such as maleic anhydride, itaconic anhydride, and citraconic anhydride; methyl (meth) acrylate, butyl (meth) acrylate, ( (Meth) acrylic acid glycidyl, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl ester, itaconic acid monomethyl ester, itaconic acid diethyl ester and the like; (meth) acrylamide, maleic acid monoamide, Maleic acid diamide, maleic acid-N-monoethylamide, maleic acid-N, N′-diethylamide, maleic acid-N-monobutyramide, maleic acid-N, N′-dibutylamide, fumaric acid monoamide, fumaric acid diamide , Fumaric acid-N-monoethyla Amides such as fumaric acid-N, N′-diethylamide, fumaric acid-N-monobutylamide, fumaric acid-N, N′-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide; ) Alkali metal salts such as sodium acrylate and potassium (meth) acrylate.

  Furthermore, among olefin resins, it is preferable to use a propylene resin from the viewpoint of chemical resistance, processability, and low cost. Propylene-based resins include propylene homopolymer and polypropylene having stereoregularity such as isotactic, syndiotactic, and atactic; propylene as a main component, and ethylene, 1-butene, 1-hexene , 1-heptene, 1-octene, and a copolymer obtained by copolymerizing one or more α-olefins such as 4-methyl-1-pentene. Further, the copolymer may be a random copolymer or a block copolymer.

  The propylene resin may be blended with a resin having a melting point 5 to 80 ° C., preferably 30 to 75 ° C. lower than the melting point of the propylene resin. Examples of the resin having a low melting point include high-density or low-density polyethylene. The compounding quantity of resin with low melting | fusing point is 0-25 mass%, Preferably it is 0-15 mass%.

  From the viewpoint of stretching stability during production of the base layer (A), the base layer (A) preferably contains 35 to 100% by mass, more preferably 40 to 100% by mass.

(Inorganic fine powder and organic filler)
In the present invention, the base layer (A) is preferably opaque in order to conceal print information printed on the printable layer (B) and the printable layer (B) described later. The opacity of the base layer (A) is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more.

As a method for making the base layer (A) opaque, a thermoplastic resin is blended with inorganic fine powder having a high refractive index, or a thermoplastic resin containing inorganic fine powder or organic filler is stretched to form pores therein. Incident light is diffusely reflected at the air hole interface, or a concealing layer (for example, whitening printing, silver printing, pigment coating layer, metal foil, metal vapor deposition film, etc.) is separately provided on the surface of the base layer (A). It is done. By these methods, the opacity of the base layer (A) can be 80% or more.
The base layer (A) contains at least one of inorganic fine powder and organic filler in an amount of 0.1 to 65% by mass, preferably 0.1 to 60% by mass.

  The volume average particle diameter that can be added to the base layer (A) is usually 0.01 μm or more, preferably 0.1 μm, from the viewpoint of achieving whitening and opacification of the base layer (A). On the other hand, from the viewpoint of improving the appearance of the in-mold label, it is usually 15 μm or less, preferably 5 μm or less. In the present invention, the volume average particle diameter is measured using a particle size distribution meter by laser diffraction of the inorganic fine powder.

  The inorganic fine powder used for the base layer (A) includes calcium carbonate, calcined clay, silica, diatomaceous earth, white clay, talc, titanium oxide, barium sulfate, alumina, zeolite, mica, sericite, bentonite, sepiolite, vermiculite. Dolomite, wollastonite, glass fiber and the like. Among these, calcium carbonate, talc, and titanium oxide are preferable from the viewpoint of whitening, opacification, and resin moldability, and calcium carbonate and titanium oxide are more preferable.

  When the base layer (A) contains an inorganic fine powder, the base layer (A) preferably contains 1% by mass or more of the inorganic fine powder from the viewpoint of increasing the opacity and whiteness of the base layer (A). More preferably 5% by mass or more. On the other hand, from the viewpoint of stretching stability during production of the base layer (A), the base layer (A) preferably contains 25% by mass or less of inorganic fine powder, and more preferably contains 20% by mass or less.

When the base layer (A) contains an organic filler, it is preferably contained in an amount of 0.01% by mass or more from the viewpoint of expressing the function of the organic filler. On the other hand, from the viewpoint of improving the appearance of the in-mold label, the content is preferably 20% by mass or less, and more preferably 10% by mass or less. As the organic filler, it is preferable to select a different type of resin from the thermoplastic resin that is the main component of the base layer (A). Among these, it is more preferable to select a resin that exhibits a higher melting point or glass transition point than the thermoplastic resin that is the main component of the base layer (A). For example, when the thermoplastic resin that is the main component of the base layer (A) is a polyolefin resin (melting point: 80 to 160 ° C.), the melting point of the organic filler is preferably 170 to 300 ° C., and the glass transition of the organic filler The point is preferably 170 to 280 ° C. Examples of the organic filler exhibiting such a melting point or glass transition point include polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-6,6 and the like.
On the other hand, it is more preferable to select a resin that is incompatible with the thermoplastic resin that is the main component of the base layer (A). When the thermoplastic resin that is the main component of the base layer (A) is a polyolefin resin, examples of the organic filler include polystyrene and polymethyl methacrylate in addition to the resins listed above. When a certain thermoplastic resin is a propylene-based resin, examples of the organic filler include high-density polyethylene, low-density polyethylene, and cyclic polyolefin in addition to the resins listed above.

(Other ingredients)
In the present invention, the base layer (A) can contain a heat stabilizer (antioxidant), a light stabilizer, a dispersant, a lubricant, or the like, if necessary.

The stabilizer is used for the purpose of suppressing the deterioration of the thermoplastic resin and using the label for in-mold molding over a long period of time. When the base layer (A) contains a heat stabilizer, it is preferable to contain 0.001% by mass or more of the heat stabilizer from the viewpoint of expressing the function of the heat stabilizer. On the other hand, from the viewpoint of improving the appearance of the in-mold label and from the viewpoint of economic efficiency, the heat stabilizer is preferably contained in an amount of 1% by mass or less, more preferably 0.5% by mass or less.
As the heat stabilizer, one or two or more kinds of conventionally known hindered phenol-based, phosphorus-based, amine-based heat stabilizers (antioxidants) can be appropriately used.

When the base layer (A) contains a light stabilizer, it is preferable to contain 0.001% by mass or more of the light stabilizer from the viewpoint of expressing the function of the light stabilizer. On the other hand, from the viewpoint of improving the appearance of the in-mold label and from the viewpoint of economic efficiency, it is preferably contained in an amount of 1% by mass or less, more preferably 0.5% by mass or less.
As the light stabilizer, one or more kinds of light stabilizers such as hindered amines, benzotriazoles, and benzophenones that are generally known can be appropriately used.
It is also preferable to use a light stabilizer in combination with the above heat stabilizer.

When the base layer (A) contains a dispersant or a lubricant, it is preferable to contain 0.01% by mass or more of the dispersant or the lubricant from the viewpoint of expressing the function of the dispersant or the lubricant. On the other hand, from the viewpoint of improving the moldability and printability of the in-mold label, the dispersant or lubricant is preferably contained in an amount of 4% by mass or less, more preferably 2% by mass or less.
Dispersants or lubricants include commonly known silane coupling agents; fatty acids having 8 to 24 carbon atoms such as oleic acid and stearic acid and their metal salts, amides, esters with alcohols having 1 to 6 carbon atoms. Etc. One or two or more of poly (meth) acrylic acid and metal salts thereof can be appropriately used.

(Formation of base layer (A))
The base layer (A) may have a single layer structure or a multilayer structure of two or more layers. Various functions such as writability, printability, scratch resistance, and secondary processing suitability can be added by multilayering the base layer (A). When the base layer (A) has, for example, a two-layer structure, the number of stretching axes of each layer constituting the base layer (A) is unstretched / unstretched, unstretched / uniaxial, uniaxial / unstretched, unstretched / biaxial, A combination of biaxial / non-stretched, monoaxial / uniaxial, monoaxial / biaxial, biaxial / uniaxial, biaxial / biaxial is mentioned.

  When stretching any layer constituting the base layer (A), the stretching method is not particularly limited, and various known methods can be used. As the stretching method, when a cast film is stretched, longitudinal stretching using the peripheral speed difference of the roll group, lateral stretching using a tenter oven, rolling, simultaneous biaxial stretching using a combination of a tenter oven and a linear motor, etc. Can be mentioned. Moreover, when extending | stretching an inflation film, simultaneous biaxial stretching by a tubular method is mentioned.

  The stretching conditions are not particularly limited, and are appropriately determined in consideration of the characteristics of the thermoplastic resin used. For example, when using a propylene homopolymer or a copolymer thereof as a thermoplastic resin, the draw ratio is about 1.2 to 12 times, preferably 2 to 10 times when drawn in one direction, and biaxially drawn. In this case, the area magnification is 1.5 to 60 times, preferably 4 to 50 times. When using other thermoplastic resins, it is 1.2 to 10 times, preferably 2 to 5 times when stretched in one direction, and preferably 1.5 to 20 times by area magnification in the case of biaxial stretching. Is 4 to 12 times.

  The stretching temperature can be carried out within a known temperature range suitable for thermoplastic resins having a glass transition temperature or higher and a melting point of the crystal part or lower. Specifically, when the thermoplastic resin is a propylene homopolymer (melting point 155 to 167 ° C.), it is 100 to 164 ° C., and when it is a high density polyethylene (melting point 121 to 134 ° C.), it is 70 to 133 ° C. 1 to 70 ° C lower temperature. In addition, polyethylene terephthalate (melting point: 246 to 252 ° C.) is selected at a temperature at which crystallization does not proceed rapidly. The stretching speed is preferably 20 to 350 m / min.

  Furthermore, it is preferable to perform heat treatment after stretching. The temperature of the heat treatment is preferably not less than the stretching temperature and not more than 30 ° C. higher than the stretching temperature. By performing the heat treatment, the thermal shrinkage rate in the stretching direction is reduced, and squeezing due to shrinkage at the time of product storage and heat and fusing sealing is reduced. The heat treatment is generally performed by a roll and a heat oven, but these may be combined. The heat treatment is preferably performed in a state where the stretched film is held under tension from the viewpoint of obtaining a high treatment effect.

  The thickness of the base layer (A) is preferably 20 μm or more, and more preferably 50 μm or more, from the viewpoint of heat insulation so that heat received from the molten resin does not escape to the mold. On the other hand, if the stiffness is too high, the base layer (A) and the printable layer (B) tend to be peeled off during normal transportation and use, so 150 μm or less is preferable, and 120 μm or less is more preferable.

(Printability of base layer (A))
In the in-mold molding label of the present invention, the base layer (A) preferably further has printing information. The print information is preferably provided on the surface of the base layer (A) on the side opposite to the printable layer (B). That is, the surface of the base layer (A) preferably has printability.
Examples of the method for enabling printing on the surface of the base layer (A) include at least one of a surface oxidation treatment and a surface coating treatment. As for the surface physical properties of the base layer (A) after the treatment, the water contact angle is preferably 70 degrees or less. The surface wetting tension is preferably 38 mN / m or more.

Examples of the surface oxidation treatment include a treatment method selected from corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, ozone treatment and the like. Of these, corona discharge treatment is preferred. In the case of corona discharge treatment, the treatment amount is preferably 10 to 200 W · min / m ² (600 to 12,000 J / m ² ) from the viewpoint of performing stable and effective treatment, and 20 to 180 W · min / m ^2. (1,200 to 10,800 J / m ² ) is more preferable.

Examples of the surface coating treatment include a method of coating a surface treatment liquid containing a polymer binder and, if necessary, an auxiliary agent such as an antistatic agent or pigment particles.
Polymeric binders include polyethyleneimine, alkyl-modified polyethyleneimine having 1 to 12 carbon atoms, poly (ethyleneimine-urea), poly (ethyleneimine-urea) ethyleneimine adduct, polyamine polyamide, and polyamine polyamide ethyleneimine addition. , And polyethylenimine polymers such as epichlorohydrin adducts of polyamine polyamide, acrylic acid ester copolymer, methacrylic acid ester copolymer, acrylic acid amide-acrylic acid ester copolymer, acrylic acid amide-acrylic acid ester-methacrylic acid Acid ester copolymers, polyacrylamide derivatives, acrylate ester polymers such as oxazoline group-containing acrylic ester polymers, polyvinylpyrrolidone, polyethylene glycol, etc., in addition to acetic acid Nyl resin, urethane resin, polyether resin, polyester resin, urea resin, terpene resin, petroleum resin, ethylene-vinyl acetate copolymer, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, vinylidene chloride resin, vinyl chloride -Vinylidene chloride copolymer resin, chlorinated ethylene resin, chlorinated propylene resin, butyral resin, silicone resin, nitrocellulose resin, styrene-acrylic copolymer resin, styrene-butadiene copolymer resin, acrylonitrile-butadiene copolymer Examples include coalescence.

  As the pigment particles, known organic or inorganic fine particles can be used. As specific examples, silicon oxide, calcium carbonate, calcined clay, titanium oxide, zinc oxide, barium sulfate, diatomaceous earth, acrylic particles, styrene particles, polyethylene particles, polypropylene particles, and the like can be used. The particle diameter of the pigment particles is preferably 5 μm or less, more preferably 3 μm or less, and still more preferably 1 μm or less.

  The surface treatment agent is dissolved in a single solvent system or mixed solvent system selected from organic solvents such as water, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, ethyl acetate, toluene, xylene, etc. It can be dispersed and used as an emulsion or dispersion state. Among these, use in the form of an aqueous solution is preferable because process management is easy. The solution concentration is usually 0.1 to 20% by weight, preferably 0.2 to 10% by weight.

As a coating method of the surface treatment agent, coating with a die coater, roll coater, gravure coater, spray coater, blade coater, reverse coater, air knife coater, size press coater, or the like can be employed.
The coating of the surface treatment agent may be performed together with the film forming in the forming line of the base layer (A), or may be performed on the already formed base layer (A) film on a separate line. If necessary, an excess solvent is removed through a drying process using an oven or the like to form a surface coating layer.

[Printable layer (B)]
In the label for in-mold molding of the present invention, the printable layer (B) is located between the base layer (A) and the heat seal layer (C), and the base layer (A) and the printable layer (B) are Interfacial debonding is possible between the two.
The interfacial peel strength between the base layer (A) and the printable layer (B) is a heat measured at a grip moving speed of 300 ± 30 mm / min in accordance with JIS Z 1707: 1997 (“General Rules for Plastic Films for Food Packaging”). The seal strength is indicated, and this value is 0.4 to 1.6 N / 15 mm.
The opacity of the printable layer (B) refers to the opacity measured according to JIS P 8149: 2000 (“Paper and paperboard—Opacity test method (backing of paper) —diffuse illumination method”). This value is 60% or less.

(Interfacial peel strength)
The interfacial peel strength between the base layer (A) and the printable layer (B) is preferably 0.4 N / 15 mm or more, and more preferably 0.6 N / 15 mm or more. When the interfacial peel strength takes such a value, it tends to be difficult to peel off when performing secondary processing such as printing, printing, and cutting on the in-mold molding label. Further, the base layer (A) is hardly lifted during in-mold molding, and the product appearance tends to be good. On the other hand, the interfacial peel strength is preferably 1.6 N / 15 mm or less, and more preferably 1.4 N / 15 mm or less. By taking such a value for the interfacial peel strength, it is easy and practically preferable to smoothly peel the two by hand.
By selecting the thermoplastic resins used for the base layer (A) and the printable layer (B), the interfacial peel strength between the base layer (A) and the printable layer (B) is in the range of 0.4 to 1.6 N / 15 mm. It is preferable to adjust.

(Tensile strength)
In order to enable interfacial delamination between the base layer (A) and the printable layer (B), not only the interfacial delamination strength of the two layers but also the base layer (A) and the printable layer (B) It is preferable that the base material has a strength that does not break itself. More specifically, the base material strength of the base layer (A) and the printable layer (B) is preferably not less than the value of the interfacial peel strength. The base material strength is JIS K 7127: 1999 ("Plastics-Test method for tensile properties-Part 3: Test conditions for films and sheets") quoted by JIS Z 1707: 1997 ("General rules for plastic films for food packaging"). In accordance with the tensile strength measured at a grip moving speed of 300 ± 30 mm / min. Each tensile strength of the base layer (A) and the printable layer (B) is preferably more than 1.6 N / 15 mm, and more preferably 3.0 N / 15 mm or more. The tensile strength of each of the base layer (A) and the printable layer (B) can be adjusted by selecting a thermoplastic resin, the amount of pores formed inside the layer, the thickness of the layer, and the like.

Furthermore, in order to peel only the base layer (A) from the resin molded product with a label, the adhesive strength between the printable layer (B) and the heat seal layer (C), the cohesive strength of the printable layer (B), the heat seal layer Both the cohesive strength of (C) and the adhesive strength between the heat-sealed layer (C) and the resin molded product in the resin molded product with a label similarly exceed the interfacial peel strength of 1.6 N / 15 mm. Preferably, it is 3.0 N / 15 mm or more.
In addition, the adhesive strength between each layer and the cohesive force in each layer can be represented by a measured average peeling force in accordance with JIS K 6854-2: 1999.

(Thermoplastic resin)
The printable layer (B) is preferably a thermoplastic resin formed into a film.
As the thermoplastic resin used for the printable layer (B), a thermoplastic resin that can be formed into a film as in the case of the base layer (A) can be used. Specifically, high-density polyethylene, medium-density polyethylene, and low-density polyethylene can be used. Polyethylene, polypropylene, propylene copolymer resin, polymethyl-1-pentene, ethylene / cyclic olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, maleic acid modified polyethylene, maleic acid modified polypropylene, etc. Olefin-based resins; Styrenic resins such as atactic polystyrene, syndiotactic polystyrene, styrene-maleic acid copolymer; polyethylene terephthalate, polyethylene terephthalate isophthalate, polybutylene terephthalate, polybutylene terephthalate, polybutyl Succinates, polybutylene adipate, ester resins such as polylactic acid; nylon-6, an amide-based resin such as nylon-6,6; and polycarbonates. Among these resins, one kind or a mixture of two or more kinds can be used.
Furthermore, since the base layer (A) and the printable layer (B) need to be interfaced, the resin composition of the base layer (A) and the resin composition of the printable layer (B) should be different. Is preferred.

Examples of the combination of the thermoplastic resin used for the base layer (A) and the printable layer (B) include polyethylene and polypropylene, polyethylene and polystyrene, polypropylene and polystyrene, polyethylene and polyethylene terephthalate, polypropylene and polyethylene terephthalate, and the like. The combinations of the thermoplastic resins used for the base layer (A) and the printable layer (B) exemplified above may be reversed in each layer. For example, polyethylene may be used for the base layer (A), polypropylene may be used for the printable layer (B), polypropylene may be used for the base layer (A), and polyethylene may be used for the printable layer (B).
The peel strength between the base layer (A) and the printable layer (B) is greatly influenced by the combination of the thermoplastic resins used in the two layers, but added to at least one of the base layer (A) and the printable layer (B). An agent can be added to adjust the peel strength.
For example, when a compatibilizing agent is added, the peel strength may be improved. In the case of a combination of polyethylene and polypropylene, examples of the compatibilizer include olefin-based thermoplastic elastomers, olefin-based adhesive resins, functional group-containing olefin-based resins, coupling agents, and the like.
On the other hand, when a release agent is added, the peel strength may be reduced. Examples of the release agent include fatty acids having 8 to 24 carbon atoms such as oleic acid and stearic acid, or fatty acid amides thereof, and esters with alcohols having 1 to 6 carbon atoms.

  In the present invention, the base layer (A) preferably contains an olefin resin, and the printable layer (B) preferably contains a styrene resin. Furthermore, the base layer (A) preferably contains an olefinic thermoplastic elastomer as a compatibilizing agent, and more preferably contains a polystyrene / olefin copolymer. When the base layer (A) contains a compatibilizer such as an olefinic thermoplastic elastomer, the content of the compatibilizer is in a range not exceeding the content of the main component resin constituting the base layer (A). Is preferred. Specifically, the mass ratio of the main component resin: the compatibilizer is preferably 8: 1 to 1: 1, and more preferably 7: 1 to 1: 1.

  When polypropylene is selected for the base layer (A) and polystyrene is selected for the printable layer (B), a compatibilizer described later can be added to the base layer (A) as a specific example of a method for adjusting the peel strength. More specifically, when a compatibilizer is blended with polypropylene so that the styrene content of the base layer (A) is 1 to 6% by mass, the peel strength between the base layer (A) and the printable layer (B) is It can be set to 0.4 to 1.6 N / 15 mm.

Further, since the printing information is visually recognized through the printable layer (B) when the base layer (A) is peeled off, it is preferable that the printable layer (B) has high transparency. As described above, the printable layer (B The opacity measured according to JIS P 8138: 2000 is 60% or less. The opacity of the printable layer (B) is preferably 50% or less, and more preferably 40% or less. When the opacity of the printable layer (B) is in such a range, there is a tendency that print information is blurred and visibility is reduced.
By using a thermoplastic resin with high transparency in the printable layer (B) or by suppressing the amount of components that increase opacity such as inorganic fine powder or organic filler, the printable layer (B) Low opacity can be achieved.

  The thickness of the printable layer (B) is less likely to cause uneven peel strength between the base layer (A) and the printable layer (B) and uneven peel strength between the printable layer (B) and the resin molded product. In view of the above, 1 μm or more is preferable and 2 μm or more is more preferable. On the other hand, it is preferably 20 μm or less, more preferably 15 μm or less, from the viewpoint of suppressing the internal haze of the printable layer (B) from increasing and the printing information of the printable layer (B) from becoming unsharp.

(Printability of printable layer (B))
The printable layer (B) preferably has printability. As a method for enabling printing on the surface of the printable layer (B), it is preferable to perform surface oxidation treatment.
As the surface oxidation treatment method, a method performed in the base layer (A) can be applied.

[Formation method of base layer (A) and printable layer (B), and lamination method of both]
The method for forming the base layer (A) as a film containing a thermoplastic resin is not particularly limited, and various known methods can be used. Specific examples include cast molding that uses a T-die connected to a screw-type extruder to extrude the molten resin into a sheet, and inflation molding that uses a circular die to extrude the molten resin into a tube and expand it with the internal air pressure. Examples thereof include calender molding, rolling molding, and the like in which the kneaded material is rolled with a plurality of hot rolls and processed into a sheet shape.
The printable layer (B) can also be formed by the same method as the method for forming the base layer (A).

  As a method of laminating the base layer (A) and the printable layer (B), co-extrusion molding in which both molten resins are laminated in a die, extrusion in which the molten resin of the other layer is extruded and laminated on one layer. Laminate molding, thermal laminate molding in which at least one of the two layers is heated and melted and laminated on the other layer, dry laminate molding or wet laminate molding in which both layers are laminated via an adhesive layer Can be used.

  Among these, co-extrusion cast molding that uses a multi-layer T die connected to a screw-type extruder, laminates the molten resin of the base layer (A) and the printable layer (B) in the same die, and extrudes it into a sheet. Therefore, the method of obtaining a laminate by simultaneously laminating and forming both layers is simple in the process, and the base layer (A) and the printable layer (B) are not compatible with each other, so that they are sufficiently separated by hand. Even if it is possible, it is preferable because it is easy to obtain an adhesive strength that does not easily peel in the processing step. The obtained laminated sheet may be stretched in the same manner as in the formation of the base layer (A).

[Print Information]
In the in-mold molding label of the present invention, the printing information is provided on the printable layer (B).
The print information is provided in advance in the in-mold molding label for the purpose of giving design and information in the in-mold molding label. In the resin-molded article with a label of the present invention, after the base layer (A) is peeled and removed, the display area on the in-mold molding label can be increased by the printing information visually recognized through the printable layer (B). It becomes.
The print information includes a printable layer (B) and a heat seal layer (C) in contact with the printable layer (B) so that the print information does not peel from the printable layer (B) when the base layer (A) is peeled from the resin molded product with a label. It is preferable that the contact is sufficient. As long as the print information is in close contact with the printable layer (B), the type and amount of the printing ink used when printing the print information and the printing method are not particularly limited.

For portions where print information is not provided on the printable layer (B), the printable layer (B) and the heat seal layer (C) are directly bonded. Note that the adhesiveness between the printing ink and the heat seal layer (C) and the printing ink and the printable layer (B) is strong even in the portion where the printing information is provided, and delamination or the like does not occur.

Therefore, any printing method such as offset printing, gravure printing, flexo printing, letter press printing, silk screen printing, electrophotographic printing, etc. can be used for printing printing information. Any ink such as mold ink, ultraviolet polymerization ink, water-based ink, and liquid toner ink can be used.
Furthermore, for printing information, not only the above printing but also variable information printing by various printers; foil stamping such as hot stamp and cold stamp; May be included.
In order to increase the adhesive strength between the printable layer (B) and the printing information (printing ink), surface activation treatment such as corona discharge treatment or anchor coat is applied to the surface of the printable layer (B) before printing. It can also be applied.

[Heat seal layer (C)]
In the in-mold molding label of the present invention, the heat seal layer (C) is the outermost layer on the side opposite to the base layer (A). The heat seal layer (C) is preferably a resin composition containing a thermoplastic resin formed into a film.
The heat seal layer (C) is activated by heat at the time of molding the resin molded product, and bonds the laminate including the base layer (A), the printable layer (B), and the printing information to the resin molded product. It has the function of an agent.

  Specific examples of the thermoplastic resin used in such a heat seal layer (C) include ultra-low density, low density, or medium density high pressure polyethylene, linear linear low density polyethylene, ethylene / vinyl acetate copolymer, Ethylene / acrylic acid copolymer, ethylene / alkyl acrylate polymer having 1 to 8 carbon atoms in the alkyl group, ethylene / methacrylic acid alkyl ester copolymer having 1 to 8 carbon atoms in the alkyl group, propylene / α Examples thereof include a propylene-based resin, a polyester-based resin, a styrene-based elastomer resin, and a polyamide-based resin typified by an olefin copolymer. Moreover, the other well-known additive for resin can be arbitrarily added to the heat seal layer (C) as long as the heat sealability is not impaired. Examples of the additive include dyes, nucleating agents, plasticizers, mold release agents, flame retardants, antioxidants, light stabilizers, and ultraviolet absorbers.

  Lamination on the heat-sealable layer (C) on the printable layer (B) is performed by laminating a film made of the resin composition of the heat-seal layer (C) by a heat laminating method, or by heat-seal layer (C). After laminating the melted resin composition by the method of extrusion lamination, coating the resin composition dissolved in a solvent or finely dispersed with various coaters, or printing with a printing machine And can be laminated by a drying method.

  The thickness of the heat seal layer (C) is preferably 0.1 μm or more, and more preferably 0.5 μm or more, from the viewpoint of obtaining sufficient adhesion to the resin molded product. On the other hand, it is preferably 20 μm or less and more preferably 10 μm or less from the viewpoint of making the in-mold molding label difficult to curl during sheet offset printing or when the label is inserted into a mold.

Conventionally, in-mold molding labels have a background that requires strong adhesion so that they do not peel off from resin molded products, and peeling and breakage at unintended locations during peeling are the weakest of the components. Since these occur at places, the adhesive strength between the in-mold molding label and the resin molded product is preferably more than 3.0 N / 15 mm, and more preferably 4.0 N / 15 mm or more. .
The adhesive strength between the label for in-mold molding and the resin molded product is the average peel force measured in accordance with the measurement of heat seal strength specified in JIS Z 1707-2: 1997 (“General Rules for Plastic Films for Food Packaging”). It refers to a value converted to a test piece width of 15 mm. The conversion is performed by dividing the measured value of the average peel force by the test piece width (mm) and multiplying by 15.
The adhesive strength between the in-mold molding label and the resin molded product can be adjusted to the above conditions depending on the raw material, molding conditions and thickness of each layer.

[Processing of labels for in-mold molding]
(Glue killing part)
The label for in-mold molding of the present invention may be one in which the surface of the heat seal layer (C) has been subjected to a treatment for adjusting the adhesive force with the resin molded product. As shown in FIG. A paste-killing portion 7 may be provided on a part of the surface of the layer (C) 3. By providing a paste-killing part on the in-mold molding label, when the label is molded in-mold, the heat seal between the heat seal layer (C) and the resin molded product is suppressed, and the label is peeled off from the resin molded product. It is possible to facilitate the start of peeling when performing. These are part of the ends of the label, since it is preferable to provide an area enough to be pinched by normal finger, the area of the adhesive-agent-dissolving portion is preferably 10 mm ² or more, more preferably 30 mm ² or more, 50 mm ² The above is more preferable. On the other hand, from the viewpoint to prevent peeling during normal transportation and use from the end of the label, the area of the adhesive-agent-dissolving portion is preferably 4500 mm ² or less, more preferably 2000 mm ² or less, more preferably 700 mm ² or less.

These paste killers can be provided, for example, by printing on the surface of the heat seal layer (C). These printing inks are not particularly limited and can be appropriately selected depending on the printing method, and any of offset ink, UV offset ink, gravure ink, silk screen ink, flexographic ink, UV flexographic ink, and the like can be used. On the other hand, when the heat seal layer (C) is applied by a coater or the like, the non-application portion may be used as a gripping portion by applying only the portion that becomes paste-killing.

(Half cut wire)
The label of the present invention is preferably provided with a half-cut line on the printable layer (B) and the heat seal layer (C) in order to cause peeling at the interface between the base layer (A) and the printable layer (B). . It is more preferable that such a half-cut line is provided along the part where the paste is killed. As shown in FIG. 3, the half-cut line 11 extends from the surface side of the heat seal layer (C) 3 to the interface between the printable layer (B) 2 and the base layer (A) 1 with respect to the surface direction. It is preferable that they are provided in series in the vertical direction.
As shown in FIG. 4, in the in-mold molding label 10, by providing the half-cut line 11, interfacial peeling is easy at the interface between the base layer (A) 1 and the printable layer (B) 2. Can be generated. This is because by providing a half-cut line, the stress applied to the heat seal layer (C) can be reduced when the paste-killing portion is grasped and peeled off. In addition, by providing a half-cut line, stress tends to be applied to the base layer (A), and interface peeling between the base layer (A) and the printable layer (B) is likely to occur. Can be demonstrated.
Half-cut lines can be cut in the same way as die-cutting using die-cut rolls, magnet cylinders, flat-cutting using Thomson blades, mainspring blades, engraving blades, corroding blades, PMC, etc., or laser-cutting .

(printing)
For printing, gravure printing, offset printing, flexographic printing, screen printing, ink jet printing, electrophotographic printing, etc. are used, and the pattern, barcode, manufacturer, sales company on the base layer (A) and printable layer (B) Designs and information such as name, character, product name, and usage can be given.
Further, after the base layer is peeled off, information such as a pattern, characters, barcodes printed on the surface of the printable layer (B) can be recognized through the printable layer (B). Therefore, printing on the printable layer (B) side is mirror image printing, and printing is performed so that it can be correctly recognized when observed through the printable layer (B). Further functions such as secondary use of the peeled label for coupons and the like can be provided.

[In-mold molding]
The present invention also relates to a resin-molded article with a label in which the label for in-mold molding as described above is attached to and integrated with a resin-molded article by in-mold molding.
The in-mold molding label of the present invention can be particularly suitably used as an in-mold label for hollow molding in which a molten resin parison is inflated with compressed air and pressed against the inner wall of the mold to form a mold shape. In the resin molded product with a label manufactured in this way, since the label and the resin molded product are integrally formed after the label is fixed in the mold, there is no deformation of the label, and there is no deformation of the molded product main body and the label. The adhesive strength is strong, there is no blister, and the appearance decorated with a label is good.
The in-mold label of the present invention can also be used as an in-mold label for differential pressure molding. At this time, the label is set so that the printing surface of the label is in contact with the inner surface of the lower female die of the differential pressure molding die, and then the label is fixed to the inner wall of the die by suction, and then the container molding material resin sheet The melt is guided to the upper part of the lower female mold, is subjected to differential pressure molding by a conventional method, and a resin molded product with a label in which the label is integrally fused to the outer wall of the molded product is molded. As the differential pressure molding, either a vacuum molding method or a pressure air molding method can be adopted, but a method using both of them and utilizing plug assist is preferable.
Here, the term “integrated” between the in-mold molding label and the resin molded product constitutes a part of the resin component constituting the resin molded product and the heat seal layer (C) of the in-mold molding label. It means a state in which a part of the resin component is bonded in a mixed state at these interfaces. Such integration can be realized by forming a labeled resin molded product by in-mold molding.

  In the resin molded product with a label for in-mold molding of the present invention, the resin molding material is not particularly limited as long as it is a thermoplastic resin, but the melting point of the resin molding material is higher than the melting point of the resin composition used for the heat seal layer (C). It is preferably 5 ° C or higher, more preferably 10 ° C or higher. The resin molding material preferably contains at least one thermoplastic resin selected from olefin-based resins, polystyrene resins, and polyethylene terephthalate resins.

  In the resin molded product with a label for in-mold molding of the present invention, the adhesive strength between the label for in-mold molding and the resin molded product is preferably more than 3.0 N / 15 mm, and more than 5.0 N / 15 mm. Is more preferable.

  The resin molded article with a label of the present invention is a household detergent, bathtub detergent, toilet bowl detergent, car wash detergent, facial cleanser, liquid soap, shampoo, rinse, deodorant, liquid bath agent, iron paste, sterilizer Containers for chemicals (bottles) used for alcohol, glaze wax, insecticides, etc .; Containers for foods (bottles) used for soft drinks, sake, soy sauce, oil, sauce, sauces, dressings, etc .; Jam, margarine, peanut butter Squeeze containers for spreads such as ketchup and mayonnaise; containers for ice cream, yogurt, etc .; containers for laundry detergent, dishwashing detergent, wet tissue, etc.

  Hereinafter, the present invention will be described more specifically with reference to production examples, examples, and test examples. However, materials, amounts used, ratios, processing contents, processing procedures, and the like can be appropriately changed without departing from the spirit of the present invention. . Accordingly, the scope of the present invention should not be construed as being limited by the specific examples shown below.

The laminated resin films of Production Examples 1 to 9 were produced according to the following procedure. Table 1 summarizes the details of the materials used in each production example. “MFR” in the table refers to a melt flow rate measured according to JIS K7210: 1999 (“Plastic-thermoplastic melt mass flow rate (MFR) and melt volume flow rate (MVR) test method”)).
Further, in the production of the laminated resin film of each production example, the types and blending ratios (% by mass) of the materials used, the presence or absence of stretching, and the thickness of each layer are shown in Table 2. Material No. described in the same table. Is the material No. described in Table 1. It corresponds to.

[Production Examples 1-5, 7-9]
The compound [A] and the compound [B] in which the materials listed in Table 1 were blended in the proportions listed in Table 2 were melt-kneaded with an extruder set at 250 ° C., and these were passed through a coextrusion die. Laminate and extrude into a film, then cool to 70 ° C. with a cooling device, base layer (A) composed of compound [A] ([A] layer), and printable layer (B) composed of compound [B] An unstretched film having a two-layer structure having (layer [B]) was obtained, and laminated resin films of Production Examples 1 to 5 and 7 to 9 were obtained.

[Production Example 6]
Compound [A] in which the materials listed in Table 1 were blended in the proportions listed in Table 2 was melt-kneaded with an extruder set at 250 ° C., and this was extruded into a sheet shape through a die, and then a cooling device To 70 ° C. to obtain a single-layer unstretched film.
This unstretched film was heated to 145 ° C., and then stretched 5 times in the longitudinal direction using the peripheral speed difference of the roll group to obtain a longitudinally uniaxially stretched film.
Separately, a blend [B] in which the materials listed in Table 1 were blended in the proportions listed in Table 2 was melt-kneaded with an extruder set at 250 ° C., and this was extruded directly into a sheet through a die, A laminate was obtained by laminating on one surface of the longitudinally uniaxially stretched film.
After heating this laminated body to 158 degreeC, it extended | stretched 9 times in the horizontal direction using the tenter stretching machine, the base layer (A) ([A] layer) which consists of a biaxially stretched film of a compound [A], and A sequentially stretched film having a two-layer structure having a printable layer (B) ([B] layer) composed of a uniaxially stretched film of the blend [B] was obtained, and this was used as a laminated resin film of Production Example 6. .

[Evaluation of laminated resin film]
Two test pieces each having a length of 150 mm and a width of 15 mm were cut out from the laminated resin films obtained in Production Examples 1 to 9, and the interfacial peel strength (N / 15 mm) between the [A] layer and the [B] layer, The thickness (μm) of the [A] layer and [B] layer, the opacity (%) of the [B] layer, and the tensile strength (N / 15 mm) of the [A] layer and [B] layer were evaluated. Details of each test example are as follows. The results are summarized in Table 2.

(Interfacial peel strength)
In accordance with JIS Z 1707, one end of the test piece is peeled off into the [A] layer and the [B] layer, one end of each layer is attached to both grips of a tensile tester, and tensile stress is applied at a test speed of 300 mm / min. In addition, the maximum stress until complete peeling was measured. The test was performed twice, and the average value was obtained as the interfacial peel strength.

(thickness)
In accordance with method A of JIS K 7130: 1999 (“Plastics—Film and Sheet—Thickness Measurement Method”), the [A] layer and the [B] layer after the interfacial debonding test are each micrometer (trade name: trade name: PG-01J (manufactured by Tecrock Co., Ltd.) was measured once, and all the average values were obtained to obtain the thickness.

(Opacity of [B] layer)
In accordance with JIS P 8149: 2000 ("Paper and paperboard-Opacity test method (backing of paper)-Diffuse illumination method"), a color meter (B) for each test piece of the [B] layer after measuring the thickness ( Product name: SM color computer, manufactured by Suga Test Instruments Co., Ltd.) was measured once each, and all average values were obtained and defined as opacity.

(Tensile strength)
In accordance with JIS K 7127: 1999 quoted by JIS Z 1707, both ends of each of the test pieces of the [A] layer after the interfacial peel test and the [B] layer after the opacity test are pulled by the tensile tester. A tensile stress was applied at a test speed of 300 mm / min, the maximum stress until breaking was measured, and all average values were obtained to obtain the tensile strength.

[Examples 1-6, Comparative Examples 1-3]
The surface of the printable layer (B) was subjected to corona discharge treatment in order to increase the adhesive strength between the printable layer (B) of the laminated resin films of Production Examples 1 to 9 obtained above and the printed layer information. On the surface of the printable layer (B) side, a mirror image of a pattern including characters for evaluation (MS Gothic, 6 to 20 points) was printed by flexographic printing to provide printing information.
Further, a heat sealant (trade name: Adcoat 1790, manufactured by Toyo Morton Co., Ltd.) containing an ethylene / vinyl acetate copolymer is applied onto the surface of the printable layer (B) side containing the printing information, and 80 The solvent component is volatilized by heating at 0 ° C., and a heat seal layer (C) (melting point 78 ° C.) having a thickness of 5 μm is provided to obtain in-mold molding labels of Examples 1 to 6 and Comparative Examples 1 to 3. It was.

  Furthermore, the labels for in-mold molding of Examples 1 to 6 and Comparative Examples 1 to 3 were punched into rectangles having a width of 109 mm and a length of 171 mm and varnished as a paste on the end 10 mm × 10 mm on the heat seal layer (C) side. Name: coater varnish “FI-L” (manufactured by T & K TOKA Co., Ltd.) was applied by flexographic printing, and a half cut was made along the paste-killed portion (see FIG. 3). This was inserted into one of the blow molds with an automatic label feeder so that the heat seal layer (C) surface was on the cavity side, and this was fixed to the split mold by suction.

Next, a high-density polyethylene (trade name: Novatec HD “HB321R”, manufactured by Nippon Polyethylene Co., Ltd., melting point 134 ° C., indicated as “HDPE” in Table 3) was melted at 200 ° C. and extruded into a cylindrical shape. Introduced in between, after clamping the split mold, 4.2 kg / cm ² of compressed air is supplied into the parison, and the parison is inflated and closely attached to the split mold to form a container and for in-mold molding The label was fused, then the molded product was cooled in the split mold at a split mold temperature of 20 ° C. for 14 seconds, and the mold was opened to obtain a resin molded product with a label.
Furthermore, the resin molding material was changed from high-density polyethylene to propylene random copolymer (trade name: Novatec PP “EG8”, manufactured by Nippon Polypro Co., Ltd., melting point 143 ° C., indicated as “r-PP” in Table 3). A labeled resin molded product was obtained in the same manner as described above except that.

[Practical evaluation of in-mold film]
The resin-molded products with labels obtained from Examples 1 to 6 and Comparative Examples 1 to 3 were used as they were, and the label sticking property, the label peeling property, and the appearance of the transferred characters were evaluated. In addition, from each of the resin-molded products with labels, two test pieces each having a length of 100 mm and a width of 15 mm are cut out so that a paste-killing portion and a half-cut portion are present within 10 mm from one end of the test piece. It used for evaluation of adhesive strength evaluation with a resin molded product. Details of each test example are as follows. The practical evaluation results are summarized in Table 3.

(Label stickiness)
The resin molded articles with labels obtained from the respective examples and comparative examples were visually observed and evaluated in the following two stages.
○: No air or air is observed between the label and the resin molded product (good)
X: Confirmed presence of soot and air (defect)

(Label peelability)
Insert a nail between the base layer (A) and the printable layer (B) of the resin-molded article with a label obtained from each example and comparative example, and partially peel the interface, and then label only the base layer (A) by hand. The state when peeled from the attached resin molded product was visually observed and evaluated in the following two stages.
○: (A) Only the layer peels cleanly (good)
X: At the time of producing the resin-molded article with a label, it was already partially peeled off at the interface between the (A) layer and the (B) layer, or when the (A) layer was about to be peeled off, B) Layers and printing information, or (B) between layers (B) and (C)

(How to see transcription characters)
The state after peeling the base layer (A) from the resin molded product with a label obtained from each example and comparative example was visually observed, and the appearance of the characters of the printed information remaining on the resin molded product was visually observed. Evaluation was made in three stages.
○: All characters can be clearly seen. (Good)
Δ: Not clear but all characters can be read. (Yes)
×: Fine characters cannot be read. (Bad)

(Adhesive strength between printable layer (B) and resin molded product)
In accordance with JIS Z 1707: 1997, a sample with the base layer (A) peeled off is prepared from a test piece cut out from each labeled resin molded product, and the resin molded product side of the sample is fixed to a tensile tester. Attached to the side gripping tool, the printable layer (B) of the test piece is attached to the gripping tool on the self-aligning side of the tensile tester, and the average peel force measured in the 180 degree peel test is converted to a test piece width of 15 mm. From these, all average values were obtained and used as the adhesive strength between the printable layer (B) and the resin molded product.

  As can be seen from Tables 2 and 3, the interfacial peel strength between the base layer (A) and the printable layer (B) is 0.4 to 1.6 N / 15 mm, and the opacity of the printable layer (B) is 60% or less. In the in-mold molding labels of Examples 1 to 6, when the resin molded article material is HDPE or r-PP, when the in-mold molding label is peeled from the labeled resin molded article, the base layer (A ) And the printable layer (B) are peeled off, and the printable layer (B), the print information, and the heat seal layer (C) are formed on the resin molded product after the in-mold molding label is peeled off. In addition, the label sticking property and the label peeling property of the resin-molded product with a label were good (◯).

On the other hand, in Comparative Example 1 where the interfacial peel strength between the base layer (A) and the printable layer (B) was low, both the label sticking property and the label peelability were poor (x). Moreover, compared with the comparative example 1 which does not contain a compatibilizing agent in a base layer (A), Examples 1-3 which contain a compatibilizing agent in a base layer (A) have interface peeling strength, so that the addition amount of a compatibilizing agent increases. Increased. However, in Comparative Example 2 in which the addition amount of the compatibilizing agent was excessive, the interfacial peel strength exceeded 1.6 N / 15 mm, but the peelability of the label was poor.
Further, in Example 5 and Comparative Example 3 containing an inorganic pigment, the opacity of the printable layer (B) is higher and the opacity is 60% compared to Example 2 in which the printable layer (B) contains no inorganic pigment. In Example 5 below, the appearance of the transferred character was acceptable (Δ) level, whereas in Comparative Example 3 in which the opacity of the printable layer (B) exceeded 60%, the appearance of the transferred character was It was a bad (x) level.

  In this example and comparative example, the tensile strength of the base layer (A) and the printable layer (B) was designed to exceed 4.0 N / 15 mm, but the tensile strength was 3.0 N / 15 mm. When it is less, the base layer (A) or the printable layer (B) is broken, so that the peelability of the label may be lowered. The heat seal layer (C) was designed so that the bond strength between the printable layer (B) and the heat seal layer (C) exceeded 4.0 N / 15 mm, but the bond strength was 3.0 N / 15 mm. If it is less than 1, the sticking property of the label may be lowered. In the examples and comparative examples, the adhesive strength between the printable layer (B) and the heat seal layer (C) exceeds 4.0 N / 15 mm, which means that the printable layer (B) The cohesive force in each layer of the heat seal layer (C) exceeds 4.0 N / 15 mm, indicating that no delamination or the like has occurred.

The resin molded product to which the label for in-mold molding of the present invention is attached looks at the print information pre-printed on the internal printable layer (B) by peeling the base layer (A) on the outermost surface of the label. be able to. For this reason, the display area of the label for in-mold molding can be increased.
In addition, according to the in-mold molding label of the present invention, in addition to increasing the display area of the label, it is possible to prevent forgery and reuse of the resin-molded product with label, and to remove the stripped label to a coupon, etc. Secondary use is also possible.

1 Base layer (A)
2 Printable layer (B)
3 Heat seal layer (C)
7 Paste kill 10 Label 11 Half cut line P Printing information

Claims (16)

An in-mold molding label comprising a base layer (A), a printable layer (B) and a heat seal layer (C) in this order,
The opacity of the printable layer (B) is 60% or less,
The printable layer (B) has print information on the surface on the heat seal layer (C) side,
An in-mold molding label, wherein an interfacial peel strength between the base layer (A) and the printable layer (B) is 0.4 to 1.6 N / 15 mm.   The label for in-mold molding according to claim 1, wherein an adhesive strength between the printable layer (B) and the heat seal layer (C) exceeds 1.6 N / 15 mm.   The in-mold label according to claim 1 or 2, wherein the base layer (A) and the printable layer (B) each have a tensile strength exceeding 1.6 N / 15 mm.   The base layer (A) contains at least one kind of thermoplastic resin (a) selected from the group consisting of an olefin resin, a styrene resin, an ester resin, an amide resin, and a polycarbonate. The label for in-mold shaping | molding as described in any one of 1-3. The printable layer (B) includes at least one thermoplastic resin (b) selected from the group consisting of an olefin resin, a styrene resin, an ester resin, an amide resin, and a polycarbonate,
The label for in-mold molding according to claim 4, wherein the thermoplastic resin (a) and the thermoplastic resin (b) are different thermoplastic resins.   The in-mold molding label according to any one of claims 1 to 5, wherein the base layer (A) contains an olefin resin, and the printable layer (B) contains a styrene resin.   The label for in-mold molding according to any one of claims 1 to 6, wherein the base layer (A) or the printable layer (B) contains at least one of a compatibilizer and a release agent. .   The base layer (A) and the printable layer (B) are laminated by any one of coextrusion molding, extrusion lamination molding, and thermal lamination molding. A label for in-mold molding described in 1.   The label for in-mold molding according to any one of claims 1 to 8, wherein the base layer (A) further has printing information on a surface not in contact with the printable layer (B).   The in-mold molding label according to any one of claims 1 to 9, wherein the opacity of the base layer (A) is 80% or more. The printable layer (B) and the heat seal layer (C) have a half-cut line,
The half-cut lines are provided in series in a direction perpendicular to the surface direction so as to reach the interface between the printable layer (B) and the base layer (A) from the surface of the heat seal layer (C). The label for in-mold molding according to any one of claims 1 to 10, wherein:   The label for in-mold molding according to any one of claims 1 to 11, wherein a paste-killing portion is provided on a part of the surface of the heat seal layer (C).   A resin-molded article with a label, wherein the label for in-mold molding according to any one of claims 1 to 12 is attached to and integrated with a resin-molded article by in-mold molding.   14. The resin molded article with a label according to claim 13, wherein the resin molded article contains at least one thermoplastic resin selected from an olefin resin, a polystyrene resin, and a polyethylene terephthalate resin.   The label according to claim 13 or 14, wherein an adhesive strength between the in-mold molding label according to any one of claims 1 to 12 and the resin molded product exceeds 3.0 N / 15 mm. Resin molded product.   When the label for in-mold molding is peeled from the resin-molded product with label, the resin molding after the peeling proceeds at the interface between the base layer (A) and the printable layer (B) and the label for in-mold molding is peeled off The resin-molded article with a label according to any one of claims 13 to 15, wherein a printable layer (B) having a printing information and a heat seal layer (C) remain on the article.

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