JP7286925B2 - Aging-less printed base film, content-resistant aging-less laminate, in-mold label, and in-mold molded container using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a printed substrate film exhibiting excellent anti-blocking properties even without aging treatment, and a laminate, in-mold label, and in-mold molded container exhibiting excellent content resistance.

In the manufacturing process of conventional printing substrate films and in-mold labels and in-mold molded containers using such films, the adhesive layer is strongly adhered by performing aging treatment, and high lamination strength is exhibited, and the adhesive layer The content resistance of the container is also improved.

In molded containers that use printed substrate films as in-mold labels, adhesives for dry lamination and extrusion lamination have generally been used to bond printed substrate films. In order to prevent peeling of the in-mold label and deterioration of the printed layer due to the contents in the container, an aging treatment was required.

Patent Documents 1 and 2 propose a laminated metal material in which a film of an acid-modified polyolefin resin is provided on a metal material. Due to the presence of curing aids, sufficient adhesive strength could not be obtained without aging.

JP-A-2002-348523 JP 2016-47647 A

The present invention has been intensively studied in view of the above. To obtain an excellent printed base film roll, and furthermore, a packaging material having excellent in-mold properties and excellent content resistance in the in-mold label application of a molded product using the printed base film. An object of the present invention is to obtain an agingless laminate, an in-mold label, and an in-mold molded container for use.

The printed base film of the present invention solves the above problems by having a base layer, a printed layer with ink, and a coat layer formed from a specific aqueous dispersion.

The present invention is characterized by the following points.
1. An aging-less printed substrate film having a substrate layer, an ink-printed layer, and a coat layer,
The printed layer is provided on one side surface of the base layer,
The coat layer is laminated on the printed layer, and is a layer formed by applying and drying an aqueous dispersion in which a polyolefin resin is dispersed,
An ageless printing substrate film, characterized in that said aqueous dispersion is substantially free of non-volatile water rendering aids.
2. The base material layer contains one or more selected from the group consisting of polyethylene terephthalate-based resins, polybutylene terephthalate-based resins, polyamide-based resins, and polypropylene-based resins, and is an unstretched film, a uniaxially stretched film, and a biaxially stretched film. One or more selected from the group consisting of films,
2. The agingless printing base film of 1 above.
3. The substrate layer has a transparent metal element-containing barrier layer,
3. The ageless printing substrate film according to 1 or 2 above.
4. The transparent metal element-containing barrier layer is one or more selected from the group consisting of an aluminum vapor deposition film, an aluminum oxide vapor deposition film, and a silicon oxide vapor deposition film.
3. The aging-less printing substrate film as described in 3 above.
5. The polyolefin resin dispersed in the aqueous dispersion has a number average particle size of 1 μm or less.
5. The agingless printing substrate film according to any one of 1 to 4 above.
6. wherein the polyolefin-based resin is a poly-α-olefin-based resin,
6. The agingless printing substrate film according to any one of 1 to 5 above.
7. The polyolefin-based resin is a polyethylene-based resin or a polypropylene-based resin,
6. The agingless printing substrate film according to any one of 1 to 5 above.
8. 8. The agingless printing substrate film according to any one of 1 to 7 above, wherein the polyolefin resin is an unsaturated carboxylic acid-modified polyolefin resin.
9. The unsaturated carboxylic acid-modified polyolefin-based resin has a structure derived from an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride in the total unsaturated carboxylic acid-modified polyolefin-based resin at 0.01% by mass or more and 5% by mass. including in the following proportions,
9. The ageless printing substrate film as described in 8 above.
10. The thickness of the coat layer is 0.05 μm or more and 5 μm or less.
10. The agingless printing substrate film according to any one of 1 to 9 above.
11. A blocking-resistant printed base film roll produced by winding the agingless printed base film according to any one of 1 to 10 above.
12. In the coating layer of the agingless printing base film according to any one of 1 to 10 above or the agingless printing base film obtained from the printing base film roll according to 11 above, a sealant film is added to the coating layer. A content-resistant, ageless laminate for packaging materials having a sealant layer formed by thermocompression bonding.
13. An in-mold label produced using the agingless printing base film according to any one of 1 to 10 above or the agingless printing base film obtained from the printing base film roll according to 11 above. .
14. 14. An in-mold molded container, wherein the in-mold label of 13 above and the molded container are integrated by in-mold molding.

According to the present invention, it is possible to obtain a printing substrate film and a printing substrate film roll excellent in blocking resistance, which exhibit excellent laminating strength (adhesive strength) and do not cause image deterioration without aging treatment. Furthermore, using the printed base film, in the in-mold label application of molded products, an agingless laminate for packaging materials, in-mold label, in-mold, which has excellent in-mold property and excellent content resistance A molded container can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing one example of the layer structure of the agingless printing base film of the present invention. FIG. 4 is a schematic cross-sectional view showing another example of the layer structure of the agingless printing base film of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a content-resistant agingless laminate of the present invention.

The ageless printed substrate film of the present invention, and the content-resistant ageless laminate, in-mold label, and in-mold molded container produced using the film are described in detail below. The present invention will be described by showing a specific example, but the present invention is not limited to this.

<Agingless printing substrate film>
The ageless printed base film of the present invention has a layer structure in which a base layer, a printed layer, and a coat layer are laminated in this order.
Furthermore, the substrate layer preferably has a transparent metal element-containing barrier layer in order to improve gas barrier properties.

The aging-less printed base film of the present invention is produced by first forming a printed layer on one side of a resin film that serves as a base layer by printing, and then forming a coat layer by coating and drying. . A heat treatment generally called aging is not essential, but there is no problem even if it is heated for coloring or fixing the printed layer or for drying the coat layer.

In addition, since the coating layer does not cause blocking and has heat-sealing property even if it is not subjected to aging treatment, the ageless printing substrate film has excellent blocking resistance and heat-sealing property.

[Base material layer]
In the ageless printed base film of the present invention, the base layer can be provided with a printed layer to impart decorativeness. Furthermore, when an in-mold label is produced, it can be used as the outermost surface layer of the in-mold label to impart resistance to external environments such as antifouling properties and resistance to cuts.
A resin film generally used as a base layer can be used for the base layer.

Specific resins include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate; polyamide resins such as nylon 6, nylon 66, and MXD6 (polymetaxylylene adipamide); cellophane; polyolefin resins such as polyethylene resins, polypropylene resins and acid-modified polyolefin resins; polystyrene resins; polyurethane resins; acetal resins;

A suitable one can be freely selected and used according to the use conditions such as the type of contents when the in-mold molded body is produced and the presence or absence of heat treatment after filling the contents. Among them, it is preferable to include one or more selected from the group consisting of polyethylene terephthalate-based resins, polybutylene terephthalate-based resins, polyamide-based resins, and polypropylene-based resins.

Moreover, the resin film constituting the substrate layer may be one or more selected from the group consisting of unstretched films, uniaxially stretched films, and biaxially stretched films.
In particular, biaxially oriented polyethylene terephthalate films or sheets are preferred.
The substrate layer may be composed of one layer or two or more layers. In the case of two or more layers, the layers may have the same composition or may have different compositions.

The resin film or resin sheet used for the base material layer has workability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, releasability, flame retardancy, and resistance to heat. Addition of lubricants, cross-linking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, etc. to plastics for the purpose of improving mold resistance, electrical properties, strength, etc. Agents, additives, and the like can be added, and the amount added can be arbitrarily added according to the purpose within a range that does not adversely affect other performances.

In addition, in order to improve the adhesiveness, the surface of the substrate layer or the film or sheet constituting the substrate layer is subjected to corona discharge treatment, ozone treatment, oxygen gas, nitrogen gas, or the like in advance before lamination. Physical treatment such as low-temperature plasma treatment and glow discharge treatment, or chemical treatment such as oxidation treatment using chemicals may be performed.

(Transparent metal element-containing barrier layer)
The substrate layer can have a transparent metal element-containing barrier layer in order to enhance gas barrier properties. Visibility to the printed layer is ensured by the transparency of the transparent metal element-containing barrier layer.
For the transparent metal element-containing barrier layer, one or more selected from the group consisting of vapor deposited aluminum films, vapor deposited aluminum oxide films, and vapor deposited silicon oxide films can be used. These deposited films can be provided on the surface of the resin film that constitutes the substrate layer.
The transparent metal element-containing barrier layer may be provided inside the substrate layer having another layer structure, or may be provided on the outermost surface of the entire substrate layer.

[Print layer]
The printed layer in the printed substrate film of the present invention is a layer printed with ink and provided on one surface of the substrate layer.

[Coating layer]
In the agingless printed base film of the present invention, the coat layer is a layer formed by applying and drying an aqueous dispersion in which a polyolefin resin is dispersed on the printed layer, and has heat sealability. Therefore, when included in a laminate, it is a layer that functions as an adhesive layer.
The polyolefin-based resin is preferably a polyethylene-based resin or a polypropylene-based resin, and more preferably modified with an unsaturated carboxylic acid.

Specifically, polyethylene (PE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), metallocene polyethylene, polypropylene. ethylene and/or propylene, vinyl acetate, and unsaturated carboxylic acids such as (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, maleic anhydride, fumaric acid, etc. and furthermore, unsaturated carboxylic acid obtained by modifying the above polyethylene resin or polypropylene resin with unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc. Examples include modified polyolefin resins.

Among these, the unsaturated carboxylic acid-modified polyolefin-based resin is preferably an unsaturated carboxylic acid-modified polyαolefin-based resin, and more preferably an unsaturated carboxylic acid-modified polyethylene-based resin or an unsaturated carboxylic acid-modified polypropylene-based resin. may be used alone, or two or more may be used in combination.

The unsaturated carboxylic acid-modified polyolefin resin has a structure derived from an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride in the total unsaturated carboxylic acid-modified polyolefin resin at a concentration of 0.5.
It is preferably contained at a ratio of 01% by mass or more and 5% by mass or less.

If the content is less than the above range, the effect of improving adhesion due to the structure derived from the unsaturated carboxylic acid or unsaturated carboxylic acid anhydride is difficult to be sufficiently exhibited. does not change.

In addition, it is preferred that the aqueous dispersion substantially does not contain a non-volatile water-improving aid. Although the non-volatile water-improving aid has the effect of uniformly dispersing the polyolefin resin in the aqueous dispersion with a small particle size, it tends to remain in the aging-less reinforcing film because it is non-volatile. , a decrease in adhesiveness is likely to occur.

The number average particle size of the polyolefin resin dispersed in the aqueous dispersion is preferably 1 nm or more and 1 μm or less. It is difficult to stably obtain an aqueous dispersion with a number average particle size of less than 1 nm. can be difficult to obtain.

The thickness of the coat layer is preferably 0.05 μm or more and 5 μm or less, or 0.05 g/m ² or more and 5 g/m ^{2 or} less, depending on the balance with the thickness of the core layer.
If the thickness is less than the above range, sufficient adhesion may not be obtained, and if the thickness is greater than the above range, it may be difficult to obtain a uniform coating layer.

<Blocking resistant printed base film roll>
The blocking-resistant printing substrate film roll of the present invention is a roll produced by winding the printing substrate film of the present invention.
The blocking-resistant printed base film roll of the present invention has a blocking resistance of 30 to 40 because the printed base film of the present invention has excellent blocking resistance even in an unaged state. It exhibits excellent blocking resistance even when stored at 0° C. for 2-4 weeks.

<Agingless laminate with content resistance>
The contents-resistant ageless laminate of the present invention comprises a coating layer of the agingless printing base film of the present invention or an agingless printing base film obtained from the blocking-resistant printing base film roll, and a sealant film. is a laminate for packaging material, which has a sealant layer formed by thermocompression bonding, and can exhibit excellent lamination strength and content resistance without aging treatment.

Since the content-resistant agingless laminate of the present invention has a substrate layer, a printed layer, and a sealant layer, it can be used as a general packaging material. Various packaging bags can also be produced by doing.

[Sealant layer]
The sealant layer is a layer made of a sealant film containing a heat-sealable resin.
The sealant layer may be composed of one layer or two or more layers. In the case of two or more layers, the layers may have the same composition or may have different compositions.
However, since the sealant layer exhibits heat-sealing properties by containing a heat-sealing resin, the layer constituting the outermost surface of the content-resistant agingless laminate contains a resin with excellent heat-sealing properties. is preferred.

As a specific heat-sealing resin, a thermoplastic resin can be used. Examples include polyethylene (PE), low density polyethylene (LDPE), medium density polyethylene (MDPE),
), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), metallocene polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)ethyl acrylate copolymer , ethylene-(meth)acrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, polyolefin resin such as polyethylene or polypropylene, and unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc. Acid-modified polyolefin resin, ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid terpolymer resin, cyclic polyolefin resin, cyclic olefin copolymer, polyethylene terephthalate (PET), polyacrylonitrile (PAN), etc. mentioned.

Among these, the sealant layer preferably contains a polyethylene-based resin, more preferably linear low-density polyethylene (LLDPE) or low-density polyethylene (LDPE).

The resin film or resin sheet used for the sealant layer has, as required, workability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, lubricity, releasability, flame retardancy, and antifungal properties. Plastic compounding agents such as lubricants, cross-linking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, etc. and additives can be added, and the amount thereof can be arbitrarily added according to the purpose within a range that does not adversely affect other performances.

In order to improve adhesion, the sealant layer or the surface of the film or sheet constituting the sealant layer may be subjected to corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas, nitrogen gas, or the like in advance before lamination. Physical treatment such as treatment, glow discharge treatment, or chemical treatment such as oxidation treatment using chemicals may be performed.

<In-mold label>
The in-mold label of the present invention is a label for in-mold molding that is produced using the printing substrate film of the present invention or the printing substrate film obtained from the printing substrate film roll.

In in-mold molding, the in-mold label of the present invention is placed in the mold when the resin composition for molding is filled into the mold to mold the resin molded product, and the resin composition and the in-mold label are placed in the mold. At the same time as the molding, the coat layer of the in-mold label is thermo-compression bonded to the surface of the molded product, and known molding methods such as blow molding and injection molding can be applied as the in-mold molding method.

By performing in-mold molding using the in-mold label of the present invention, the step of attaching a label to a molded product becomes unnecessary, and labor can be saved. In addition, since the in-mold label is completely adhered to the surface of the molded product, the adhesion interface is excellent in peel resistance, water resistance, oil resistance, chemical resistance and abrasion resistance.

Further, since the in-mold label of the present invention is a label made of resin instead of paper, it can be recycled without being separated from the resin molded product by peeling it off depending on the recycling method.

<In-mold container>
The in-mold molded container of the present invention is a labeled molded container obtained by integrally molding the in-mold label of the present invention and the resin composition for molding by in-mold molding.
As the method of in-mold molding, known molding methods such as blow molding and injection molding can be applied, and as the resin contained in the resin composition for molding, it is possible to use known resins for molding containers.

Examples were carried out using the following raw materials. Tables 1 and 2 show the level details and evaluation results of each example and comparative example.
- Aqueous dispersion 1: Arrow Base manufactured by Unitika Ltd. An aqueous dispersion in which particles having a number average particle diameter of 1 μm or less and made of an unsaturated carboxylic acid-modified polyethylene resin (containing 0.01 to 5% by mass of unsaturated carboxylic acid-derived skeleton) are dispersed. It is substantially free of non-volatile water rendering aids.
- Aqueous dispersion 2: Arrow Base manufactured by Unitika Ltd. An aqueous dispersion in which particles having a number average particle diameter of 1 μm or less and made of an unsaturated carboxylic acid-modified polypropylene resin (containing 0.01 to 5% by mass of unsaturated carboxylic acid-derived skeleton) are dispersed. It is substantially free of non-volatile water rendering aids.
- PET film 1: Biaxially oriented PET film manufactured by Toyobo Co., Ltd. 12 μm thick.
- Transparent vapor-deposited PET film 2: A PET film having an aluminum oxide vapor-deposited film on one side. 12 μm thickness:
DL Adhesive 1: A two-liquid curable polyester urethane dry laminate adhesive manufactured by Toyo-Morton Co., Ltd.
• PE film 1: LLDPE film. 40 μm thick.

[Example 1]
On one side of the PET film 1, a printed layer is formed by printing using ink, and the aqueous dispersion 1 is continuously applied onto the printed layer so that the coating amount after drying becomes 1 μm, dried and coated. Layers were formed to obtain a printing substrate film, and a printing substrate film roll was produced.
Next, the printed substrate film obtained above was inserted as an in-mold label into a predetermined position of the female mold of the injection mold and fixed by vacuum suction.

Then, after the mold was closed, molten polyethylene was injected from the gate at the center of the bottom of the female mold to obtain a labeled molded product in which the in-mold label and the injected resin were integrated.
The molten polyethylene was injected smoothly without any unfilling, and defects such as overlapping portions, curling, and wrinkles did not occur in the label portion of the labeled molded product.

[Example 2]
A printing substrate film was obtained by operating in the same manner as in Example 1, and a printing substrate film roll was produced.
Next, the coat layer surface of the printing substrate film obtained above and the sealant film made of PE film 1 were thermocompression bonded with a roll heated at 140° C. to obtain a laminate. Then, various evaluations were carried out.

[Example 3]
A printed substrate film was obtained in the same manner as in Example 1 except that the PET film 1 was changed to a transparent vapor-deposited PET film 2 and a printed layer was formed on the vapor-deposited surface, and a printed substrate film roll was obtained. made.
Next, a laminate was obtained by operating in the same manner as in Example 2 and evaluated in the same manner.

[Example 4]
A printing base film was obtained in the same manner as in Example 1, except that the aqueous dispersion 1 was changed to the aqueous dispersion 2, and the melted polyethylene was changed to melted polypropylene. was made.
Next, a laminate was obtained by operating in the same manner as in Example 1 and evaluated in the same manner.

[Comparative Example 1]
A printing substrate film and a labeled molded product were produced in the same manner as in Example 1 except that the aqueous dispersion 1 was changed to DL adhesive 1, and evaluated in the same manner.
However, although an attempt was made to produce a roll of the printing base film, the blocking was severe, so the roll of the printing base film was not produced.

[Comparative Example 2]
A printing substrate film and a laminate were produced in the same manner as in Example 2 except that the aqueous dispersion 1 was changed to the DL adhesive 1, and evaluated in the same manner.
However, although an attempt was made to produce a roll of the printing base film, the blocking was severe, so the roll of the printing base film was not produced.

<Evaluation method>
[Blocking resistance of printed base film roll]
After the printing base film roll was stored at 30° C. for 2 weeks, the printing base film was taken out from the printing base film roll.

[Label affixability]
In in-mold molding to obtain a labeled product in which the in-mold label and the injected resin are integrated, if the in-mold label part does not have defects such as overlapping parts, turning up, wrinkles, etc., it is considered good. bottom.

[Laminate strength]
The laminate was cut into strips of 15 mm×100 mm, and the laminate strength between the coat layer and the molded article and between the coat layer and the sealant layer was measured using a tensile tester.

[Content resistance]
Using the laminate, a bag was prepared with heat sealing on three sides, filled with 80% by weight of ethanol, sealed, and stored at 40° C. for 2 weeks.

Then, the presence or absence of image collapse on the printed layer was visually checked, the used bag was disassembled to prepare a test piece for measuring the laminate strength, and the laminate strength between the coat layer and the sealant layer was measured.

[Summary of evaluation results]
All examples show good blocking resistance, lamination strength, and content resistance without aging, but Comparative Examples 1 and 2 using a dry lamination adhesive for the coating layer have poor blocking resistance, lamination It showed strength and content resistance.

Reference Signs List 1 Agingless printed base film 2 Base layer 2a Resin film 3 Printed layer 4 Coat layer 5 Transparent metal element-containing barrier layer 6 Content-resistant agingless laminate 7 Sealant layer

Claims (8)

An agingless printing substrate film for in-mold labels , comprising a substrate layer, an ink-printed layer, and a coat layer,
The substrate layer contains one or more selected from the group consisting of polyethylene terephthalate-based resins, polybutylene terephthalate-based resins, polyamide-based resins, and polypropylene-based resins, and is an unstretched film, a uniaxially stretched film, and a biaxially stretched film. One or more selected from the group consisting of films,
The printed layer is provided on one side surface of the base layer,
The coat layer is laminated on the printed layer and is a coated dry layer of an aqueous dispersion in which a polyolefin resin is dispersed,
The polyolefin-based resin is an unsaturated carboxylic acid-modified polyethylene-based resin or an unsaturated carboxylic acid-modified polypropylene-based resin. Contained in the resin at a ratio of 0.01% by mass or more and 5% by mass or less,
The aqueous dispersion (except for cases containing aliphatic glycidyl ethers and polyester resins) further contains substantially no non-volatile water-enhancing aid,
An agingless printing substrate film for in-mold labels, wherein the coating layer has a thickness of 0.05 μm or more and 5 μm or less. The ageless printing substrate film for in-mold labels according to claim 1, wherein the substrate layer has a transparent metal element-containing barrier layer. The aging-free in-mold label according to claim 2, wherein the transparent metal element-containing barrier layer is one or more selected from the group consisting of an aluminum vapor deposition film, an aluminum oxide vapor deposition film, and a silicon oxide vapor deposition film. Printed substrate film. The agingless printing base film for in-mold labels according to any one of claims 1 to 3, wherein the polyolefin resin dispersed in the aqueous dispersion has a number average particle size of 1 µm or less. . A blocking-resistant printed base film roll produced by winding the agingless printed base film for in-mold labels according to any one of claims 1 to 4. The agingless printing base film for in-mold labels according to any one of claims 1 to 4, wherein the coat layer has a sealant layer formed by thermocompression bonding of a sealant film, content-resistant content for packaging materials Physical aging-less laminate. An in-mold label produced using the agingless printing base film for in-mold labels according to any one of claims 1 to 4. An in-mold molded container, wherein the in-mold label according to claim 7 and the molded container are integrated by in-mold molding.

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