Laminate film and coat film

Abstract

To provide a laminate film and a coat film which are easily recycled, contribute to environmental load reduction, and are suitable for mass production.SOLUTION: In a laminate film 10 in which a laminate in which a laminate layer 30 is formed on one side of a substrate film 20 by extrusion processing is separated into the substrate film 20 and the laminate layer 30 by aqueous solution, and a recycling raw material can be recovered, the substrate film 20 is a coat film 25 which is made of thermoplastic resin, and has a coat layer 21 coated with a coating agent containing polyethylene imine-based resin and wax emulsion on one side where the laminate layer 30 is formed, and equipped with the laminate layer 30 via the coat layer 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated film having a laminate layer formed on one side of a base film, and a coated film used in the laminated film. [Background technology]

[0002] Laminated films, consisting of multiple resin films layered together, are commonly used in packaging materials for foods, daily necessities, and other products. These types of laminated films are layered with various functions to ensure high quality. In recent years, the promotion of the Sustainable Development Goals (SDGs) has led to efforts to realize an environmentally friendly, recycling-oriented society. One of the milestones in the plastic resource circulation strategy is to design products that are reusable and recyclable. This has led to calls for recycling in this type of resin film as well.

[0003] In laminated films, multiple films are composed of different types of resin materials to impart various functions. Therefore, when the resins in a laminated film are remelted during recycling, the resulting material is a mixture of incompatible resins. Such a mixture of incompatible resins significantly reduces the quality of the recycled resource and is unsuitable as a recycled raw material. Therefore, as a means of recycling laminated films, laminated films that can be reused by peeling off the film layers have been proposed (see, for example, Patent Document 1).

[0004] In this laminate film, the ink layer laminated on the olefin substrate is peeled off by contact with an alkaline aqueous solution, allowing the olefin substrate to be recovered and recycled with quality close to that of virgin material. However, the above laminate film requires the use of a treatment liquid such as a strong alkaline aqueous solution to peel off the ink layer. Therefore, problems such as waste liquid disposal and environmental impact due to the use of alkaline aqueous solutions cannot be avoided. Furthermore, this type of environmentally friendly laminate film is required to be widely used as a replacement for conventional laminate films, and it is desirable that it be able to be mass-produced appropriately. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-101885 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above points, and provides a laminated film and a coated film that are easy to recycle, contribute to reducing the environmental load, and are suitable for mass production. [Means for solving the problem]

[0007] That is, the first invention relates to a laminate film in which a laminate layer is formed on one side of a base film by extrusion processing, and the laminate can be peeled into the base film and the laminate layer using an aqueous solution, allowing the recycled raw materials to be recovered, wherein the base film is made of a thermoplastic resin, and the side on which the laminate layer is formed is a coated film having a coating layer coated with a coating agent containing a polyethyleneimine resin and a wax emulsion, and the laminate layer is provided via the coating layer.

[0008] A second invention relates to the laminated film of the first invention, wherein the solid content ratio of the polyethyleneimine resin to the wax emulsion in the coating agent is 3:2 to 2:3.

[0009] The third invention is the first invention, wherein the coating amount of the coating agent is 0.1 g / m on one side. 2 The present invention relates to the following laminated film.

[0010] A fourth invention relates to the laminated film of the first invention, wherein the lamination strength between the coated film and the laminate layer is 2.0 N / 15 mm or more.

[0011] The fifth invention is the first invention, wherein the shear blocking strength between the coating layer side and the other side when the coated film is wound into a roll is 5.0 N / 4 cm 2 The present invention relates to the following laminated film.

[0012] A sixth invention relates to the laminated film of the first invention, wherein the coating agent contains a nonionic surfactant.

[0013] A seventh invention relates to the laminated film of the first invention, wherein the coating agent contains cellulose nanofibers.

[0014] An eighth invention relates to the laminated film of the first invention, wherein the thermoplastic resin contains at least one of a plant-derived raw material and a recycled resin raw material.

[0015] The ninth invention relates to a coated film used in a laminate in which a laminate layer is formed on one side of a base film by extrusion processing, characterized in that the base film is made of a thermoplastic resin, and the side on which the laminate layer is formed has a coating layer coated with a coating agent containing a polyethyleneimine resin and a wax emulsion, the coating layer being dissolvable in an aqueous solution, and the laminate is configured so that the base film and the laminate layer can be peeled off by the aqueous solution.

[0016] A tenth invention relates to the coated film of the ninth invention, wherein the solid content ratio of the polyethyleneimine resin to the wax emulsion in the coating agent is 3:2 to 2:3.

[0017] The eleventh invention is the ninth invention, wherein the coating amount of the coating agent is 0.1 g / m on one side. 2 The present invention relates to the following coated films.

[0018] A twelfth aspect of the present invention relates to a coated film having a lamination strength of 2.0 N / 15 mm or more when combined with the laminate layer formed by extrusion processing the coated film of the ninth aspect.

[0019] The thirteenth aspect of the present invention is a coated film according to the ninth aspect, wherein the shear blocking strength between the coating layer side and the other side when the coated film is wound into a roll is 5.0 N / 4 cm 2 The present invention relates to the following coated films.

[0020] A fourteenth invention relates to the coated film of the ninth invention, wherein the coating agent contains a nonionic surfactant.

[0021] A fifteenth invention relates to the coated film of the ninth invention, wherein the coating agent contains cellulose nanofibers.

[0022] A sixteenth aspect of the present invention relates to the coated film of the ninth aspect, wherein the thermoplastic resin contains at least one of a plant-derived material and a recycled resin material. [Effects of the Invention]

[0023] According to a first aspect of the present invention, there is provided a laminate film comprising a laminate in which a laminate layer is formed on one side of a base film by extrusion processing, and the laminate can be peeled into the base film and the laminate layer using an aqueous solution, thereby enabling recovery of recycled raw materials. The base film is made of a thermoplastic resin, and the side on which the laminate layer is formed is a coated film having a coating layer coated with a coating agent containing a polyethyleneimine resin and a wax emulsion. Because the laminate layer is provided via the coating layer, the base film can be easily recovered as recycled raw materials, which can greatly contribute to reducing environmental load. In addition, the coated film can be smoothly unwound from a film roll during extrusion processing, which can improve productivity and is suitable for mass production.

[0024] According to the laminated film of the second invention, since the solid content ratio of the polyethyleneimine resin to the wax emulsion in the coating agent in the first invention is 3:2 to 2:3, the adhesion and anti-blocking performance of the coating layer can be appropriately controlled.

[0025] According to the laminated film of the third invention, in the first invention, the coating amount of the coating agent is 0.1 g / m on one side. 2 Since the thickness is less than or equal to 100 μm, the adhesiveness and anti-blocking performance of the coating layer can be appropriately ensured.

[0026] According to the laminated film of the fourth invention, in the first invention, the lamination strength between the coated film and the laminate layer is 2.0 N / 15 mm or more, so that delamination between layers can be appropriately suppressed.

[0027] According to the fifth aspect of the present invention, the laminated film of the first aspect of the present invention has a shear blocking strength of 5.0 N / 4 cm between the coating layer side and the other side when the coated film is wound into a roll. 2 Since the thickness is less than 100 μm, the coated film can be smoothly unwound from the film roll.

[0028] According to the laminated film of the sixth invention, since the coating agent in the first invention contains a nonionic surfactant, defects such as repelling when applying the coating agent to the base film can be reduced, and further, the base film and the laminate layer can be more easily peeled off.

[0029] According to the laminated film of the seventh invention, since the coating agent in the first invention contains cellulose nanofibers, defects such as repelling when applying the coating agent to the base film can be reduced, and further, the base film and the laminate layer can be more easily peeled off.

[0030] According to the laminated film of the eighth invention, since the thermoplastic resin in the first invention contains at least one of plant-derived raw materials and recycled resin raw materials, it can contribute to reducing the environmental load.

[0031] According to a ninth aspect of the present invention, there is provided a coated film used in a laminate in which a laminate layer is formed on one side of a base film by extrusion processing, the base film being made of a thermoplastic resin, and the side on which the laminate layer is formed having a coating layer coated with a coating agent containing a polyethyleneimine resin and a wax emulsion, the coating layer being dissolvable in an aqueous solution, and the laminate being configured so that the base film and the laminate layer can be peeled off by the aqueous solution. This makes it possible to easily recover the base film as a recycled material, which can greatly contribute to reducing the environmental load, and also enables the coated film to be smoothly unwound from a film roll during extrusion processing, which can improve productivity and is suitable for mass production.

[0032] According to the coated film of the tenth invention, in the ninth invention, the solids ratio of the polyethyleneimine resin to the wax emulsion in the coating agent is 3:2 to 2:3, so that the adhesion and anti-blocking performance of the coating layer can be appropriately controlled.

[0033] According to the coated film of the eleventh invention, in the ninth invention, the amount of the coating agent applied is 0.1 g / m on one side. 2 Since the thickness is less than or equal to 100 μm, the adhesiveness and anti-blocking performance of the coating layer can be appropriately ensured.

[0034] According to the coated film of the 12th invention, the lamination strength with the laminate layer formed by extrusion processing on the coated film of the 9th invention is 2.0 N / 15 mm or more, so that interlayer delamination can be appropriately suppressed.

[0035] According to the coated film of the thirteenth invention, when the coated film of the ninth invention is wound into a roll, the shear blocking strength between the coating layer side and the other side is 5.0 N / 4 cm 2 Since the thickness is less than 100 μm, the coated film can be smoothly unwound from the film roll.

[0036] According to the coated film of the fourteenth invention, in the ninth invention, the coating agent contains a nonionic surfactant, which reduces defects such as repelling when applying the coating agent to the base film, and further makes it easier to peel the base film and the laminate layer.

[0037] According to the coated film of the 15th invention, in the 9th invention, the coating agent contains cellulose nanofibers, which reduces defects such as repelling when applying the coating agent to the base film, and also makes it easier to peel the base film and the laminate layer.

[0038] According to the coated film of the sixteenth invention, in the ninth invention, the thermoplastic resin contains at least one of plant-derived raw materials and recycled resin raw materials, which can contribute to reducing the environmental load. [Brief explanation of the drawings]

[0039] [Figure 1]1 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. [Figure 2] FIG. 10 is a schematic cross-sectional view of a laminated film according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0040] 1 is a laminate film 10 according to one embodiment of the present invention, which is a laminate including a base film 20 and a laminate layer 30, and which can be separated into the base film 20 and the laminate layer 30 to recover recycled raw materials. This laminate film 10 can be suitably used for various packages (packaging bags) for food, cosmetics, medicines, daily necessities, parts, other products, etc.

[0041] The recycled material of the present invention is a base film 20 obtained by peeling a laminated film 10 into a base film 20 and a laminate layer 30. This recycled material corresponds to a virgin material with nearly the same quality as a new product, since no other layers such as the laminate layer 30 are bonded to the peeled base film 20.

[0042] The base film 20 is a film made of a thermoplastic resin. Examples of the thermoplastic resin constituting the base film 20 include polyolefin resins (e.g., polypropylene resins, polyethylene resins, propylene-ethylene copolymers, etc.), polyester resins (e.g., polyethylene terephthalate, etc.), polyamide resins (e.g., nylon 6, nylon 66, etc.), and vinyl resins (e.g., polyvinyl alcohol, ethylene-vinyl alcohol copolymers, etc.). These resins can be used alone or in combination of two or more. The base film 20 may be an unstretched film, or a stretched film such as a uniaxially stretched or biaxially stretched film, depending on the application.

[0043] Furthermore, the thermoplastic resin preferably contains at least one of plant-derived raw materials and recycled resin raw materials. Plant-derived raw materials are resin materials obtained by appropriately processing plant raw materials, such as biomass polyolefins (biomass polypropylene, biomass polyethylene, etc.), biomass polyesters, and biomass vinyl resins. Recycled resin raw materials are resin materials made reusable by subjecting thermoplastic resin molded products to recycling processes such as material recycling and chemical recycling. Examples of resin molded products that can be used as recycled resin raw materials include scrap materials such as offcuts generated during the production of resin molded products such as films, materials generated during product manufacturing processes before they are released to the market, and materials recovered and recycled from used products such as waste resin molded products. The inclusion of plant-derived raw materials or recycled resin raw materials in thermoplastic resins can contribute to reducing environmental impact, and the greater the blending ratio of these raw materials, the greater the contribution.

[0044] The laminate layer 30 is a resin layer formed by extrusion on one side of the base film 20. A general polyethylene-based resin can be appropriately used for this laminate layer 30. The polyethylene-based resin is selected from at least one of ethylene homopolymers polymerized from ethylene monomers, such as low-density polyethylene and high-density polyethylene, and copolymers of ethylene and olefin comonomers, such as ultra-low-density polyethylene, linear low-density polyethylene, and high-density polyethylene.

[0045] The extrusion process for forming a laminate mainly includes known extrusion molding methods such as the T-die method. This type of extrusion process is preferable from the viewpoint of reducing the environmental load because no solvent is used during film formation. Furthermore, the T-die method is particularly preferable as an extrusion process. Film formation using the T-die method is advantageous in that it can achieve the high thickness precision required for the base film of a laminate film.

[0046] In the laminate film 10 of the present invention, the base film 20 is formed as a coated film 25 having a coating layer 21 provided on one side on which the laminate layer 30 is formed, and the laminate layer 30 is provided via the coating layer 21. In the embodiment, the coated film 25 is wound into a film roll, and during the extrusion processing of the laminate, the coated film 25 is unwound from the film roll, and at the same time, a polyethylene resin molten at a high temperature (for example, about 250 to 350°C) is extruded onto the coated film 25, thereby forming the laminate film 10 in which the laminate layer 30 is laminated on the coated film 25.

[0047] The coating layer 21 is a layer formed by coating a coating agent containing a polyethyleneimine resin and a wax emulsion on the base film 20. This coating layer 21 is soluble in an aqueous solution, which will be described later.

[0048] The polyethyleneimine resin is a water-soluble anchoring agent that has the property of increasing the laminate strength between the base film 20 and the laminate layer 30. Because this polyethyleneimine resin has high polarity and ionicity, it exhibits good adhesion to oxidized polyethylene resin when melted at high temperatures.

[0049] The wax emulsion is a lubricant obtained by emulsifying wax and provides anti-blocking properties to the coated film 25. Examples of waxes that can be emulsified include known waxes, such as natural waxes such as paraffin wax, microcrystalline wax, carnauba wax, candelilla wax, Japan wax, and rice wax, and synthetic waxes such as polyethylene wax and Fischer-Tropsch wax. These waxes can be emulsified by emulsifying and dispersing them with a surfactant or the like. The wax emulsion can reduce the occurrence of wrinkles in the coated film 25 and improve the slipperiness between films, thereby suppressing blocking during winding and improving winding properties.

[0050] The coating agent is a mixed material containing the polyethyleneimine resin and wax emulsion, and by forming the coating layer 21, it improves the adhesion (lamination strength) between the base film 20 (coating film 25) and the laminate layer 30 and imparts anti-blocking properties to the coating film 25. The coating agent can control the adhesion and anti-blocking properties of the coating layer 21 by adjusting the solid content ratio of the polyethyleneimine resin and the wax emulsion. A preferred solid content ratio of the coating agent is approximately 3:2 to 2:3 for the polyethyleneimine resin and the wax emulsion. If the proportion of the polyethyleneimine resin is too low, the laminate strength may be insufficient, and if the proportion of the wax emulsion is too low, the anti-blocking properties may be insufficient.

[0051] The solids concentration is preferably 0.1 to 2.0%, for example. Preferably, it is 0.1 to 1.0%, and more preferably 0.2 to 0.5%. If the solids concentration is too high, the coating efficiency may decrease and uniform coating may become difficult. If the solids concentration is too low, repelling may occur in the coating film, resulting in poor adhesion to the polyethylene resin. It is preferable that the wax emulsion particles are large relative to the thickness of the polyethyleneimine resin layer, and the solids concentration is preferably adjusted taking into account the particle size.

[0052] The amount of coating agent applied is not particularly limited as long as it does not impair the adhesion between layers or the anti-blocking performance, but it is preferable to apply a relatively small amount. A preferred amount of coating agent applied is, for example, 0.1 g / m on one side. 2 or less, more preferably 0.05 g / m per side 2 More preferably, 0.02 g / m per side 2If the amount of coating agent applied is too large, the anti-blocking performance may be impaired. By applying an appropriate amount of coating agent, the adhesion and anti-blocking performance of the coat layer 21 can be adequately ensured. There is no particular lower limit to the amount of coating agent applied, but from the viewpoint of ensuring adhesion and anti-blocking performance, for example, 0.02 g / m per side is preferred. 2 The degree is preferable.

[0053] Furthermore, in the laminate film 10, the laminate strength between the coat film 25 and the laminate layer 30 is preferably 2.0 N / 15 mm or more. The laminate strength is measured in accordance with JIS K 68954-3 (1999). If the laminate strength is too low, the adhesion between the coat film 25 and the laminate layer 30 may be insufficient, which may result in delamination between the coat film 25 and the laminate layer 30. By providing the laminate film 10 with the above-mentioned laminate strength, delamination can be appropriately suppressed.

[0054] Furthermore, in the laminate film 10, it is preferable to enhance the anti-blocking performance of the coat film 25 from the viewpoint of productivity (mass production) and the like. The shear blocking strength (shear peel strength) of the coat layer 21 side and the other side when wound into a roll can be used as an indicator of the anti-blocking performance of the coat film 25. The shear blocking strength is measured by overlapping the coat layer 21 side and the other side, assuming the wound state of the coat film 25.

[0055] A preferred shear blocking strength is, for example, 5.0 N / 4 cm 2 Less than 4.0N / 4cm, preferably 4.0N / 4cm 2 Less than or equal to 3.0N / 4cm, more preferably 2 Below 2.0N / 4cm, especially preferred 2If the shear blocking strength is too high, films tend to adhere to each other, which can cause flapping when the rolled (wound) coated film 25 is unwound, resulting in uneven tension and the risk of wrinkling, breakage, etc. If the coated film 25 has an appropriate shear blocking strength, the coated film 25 can be unwound smoothly from the film roll.

[0056] Considering its use as a packaging material, the laminate film 10 preferably has the transparency required for packaging applications. The transparency of the film is expressed by the haze measured in accordance with JIS K 7136 (2000), and a preferred haze is 10% or less. If the haze is too high, the transparency generally required for packaging films and the like may be insufficient, which is undesirable. By providing the laminate film 10 with an appropriate haze, good transparency suitable for packaging applications can be obtained.

[0057] When the substrate film 20 of the laminate film 10 of the present invention is recovered as a recycled material, the substrate film 20 and the laminate layer 30 are peeled off using an aqueous solution. The aqueous solution is a solution containing H2O as a main component, such as tap water, distilled water, pure water, ultrapure water, ion-exchanged water (deionized water), natural water, or mineral water. This aqueous solution may contain trace amounts of impurities, such as chlorine contained in tap water or minerals contained in natural water or mineral water. A surfactant may also be added as needed. Tap water is preferred as the aqueous solution because it is inexpensive and readily available.

[0058] Interlayer delamination of the laminate film 10 due to an aqueous solution occurs when the coating layer 21 of the coating film 25 interposed between the base film 20 and the laminate layer 30 is soluble in an aqueous solution, and thus the coating layer 21 is dissolved by bringing the laminate film 10 into contact with the aqueous solution, thereby dissolving the adhesive state between the base film 20 and the laminate layer 30. This occurs because the coating layer 21 contains a water-soluble polyimine resin as an anchor agent, and is dissolved in the aqueous solution, causing the adhesive effect of the anchor agent to be lost.

[0059] The peeling treatment of the laminate film 10 using an aqueous solution is not particularly limited as long as it is a method that allows sufficient contact between the laminate film 10 and the aqueous solution. Suitable treatments are possible, such as immersing the laminate film 10 in a sufficient amount of aqueous solution or immersing the laminate film 10 in the aqueous solution and stirring it. The contact conditions with the aqueous solution are appropriately set depending on the type of peeling treatment. For example, the laminate film may be crushed using a known film crusher, and then contacted with the aqueous solution while stirring using a known stirring device with a general stirring blade. The stirring device may be a batch type, a continuous type, or any other suitable type.

[0060] Furthermore, the peeling state (peeling rate) of the laminated film 10 caused by contact with the aqueous solution is preferably 50% or more peeled, and more preferably 90% or more peeled, when the peeling rate is calculated from the weight of the film. If the peeling rate is too low, it becomes difficult to recover the base film 20 in high quality, and the quality required for a recycled material may be impaired. If the peeling rate of the base film 20 is sufficient, the quality required for a recycled material can be ensured, and the higher the peeling rate, the more likely it is that the base film 20 can be recovered appropriately in high quality.

[0061] In the laminate film 10 of the present invention, a nonionic surfactant may be contained in the coating agent for forming the coating layer 21 to facilitate penetration of the aqueous solution into the coating layer 21 during a peeling treatment using the aqueous solution. The nonionic surfactant is a wetting agent that inhibits the coating layer 21 from repelling the aqueous solution and promotes penetration of the aqueous solution. Examples of nonionic surfactants include water-soluble surfactants with an HLB of 10 or higher that are used in cleaning agents, such as polyoxyethylene distyrenated phenyl ether, polyoxyethylene lauryl ether, and polyoxyalkylene alkyl ether. By including a nonionic surfactant in the coating agent, the coating layer 21 becomes more easily dissolved in the aqueous solution, thereby reducing defects such as repelling when applied to a substrate film.

[0062] Furthermore, from the viewpoint of facilitating penetration of the aqueous solution into the coating layer 21 during the peeling treatment with the aqueous solution, cellulose nanofibers may be contained in the coating agent for forming the coating layer 21. The cellulose nanofibers are a thickener that suppresses the repelling of the aqueous solution from the coating layer 21 and makes the coating layer 21 more wettable. Examples of cellulose nanofibers include mechanically defibrated and chemically defibrated cellulose nanofibers, and a representative example of the latter is carboxymethylated cellulose nanofibers. When the coating agent contains cellulose nanofibers, the coating layer 21 becomes more easily dissolved in the aqueous solution, and defects such as repelling can be reduced when the coating is applied to a substrate film.

[0063] In the laminate film of the present invention, other layers may be provided as needed, or multiple base films or laminate films may be provided, as long as the object of the present invention is not impaired. Examples of other layers include layers having appropriate functionality, such as a printing layer, an adhesive layer, and a protective layer. The order in which each layer is laminated can be appropriately determined as long as the functionality of each layer is not impaired.

[0064] The laminate film 10A shown in FIG. 2 includes multiple base films 20a, 20b and laminate layers 30a, 30b, laminated in the following order: first base film 20a, first laminate layer 30a, second base film 20b, and second laminate layer 30b. The first base film 20a is a coated film 25A having a coating layer 21a coated on one surface, with the coating layer 21a interposed between the first base film 20a and the first laminate layer 30a. The second base film 20b is a coated film 25B having coating layers 21b, 21c coated on both surfaces, with the coating layer 21b interposed between the first laminate layer 30a and the second laminate layer 30b. When a laminate layer or other layer is laminated on a base film in this manner, the base film is a coated film coated with a coating layer on the side where the laminate layer or other layer is to be laminated. This allows the coating layers to be dissolved by a stripping treatment using an aqueous solution, thereby allowing the multiple substrate layers to be properly stripped.

[0065] As described above, the laminate film 10 of the present invention is an environmentally friendly laminate obtained by extrusion processing without using solvents or the like during molding, and is a film in which a base film 20 is coated with a coating film 25 having a coating layer 21 containing a water-soluble polyethyleneimine-based resin, and a laminate layer 30 is laminated on the base film 20 (coated film 25) via the coating layer 21. Furthermore, because the coating layer 21 is soluble in an aqueous solution, there is no need to use an alkaline aqueous solution or the like as in the conventional peeling process, and the base film 20 and the laminate layer 30 can be easily peeled off using an aqueous solution. Therefore, in this environmentally friendly laminate, the base film 20 can be easily recovered as a recycled material, which can greatly contribute to reducing the environmental burden.

[0066] Furthermore, in the laminate film 10 of the present invention, since the coating layer 21 contains a wax emulsion, it is possible to impart appropriate anti-blocking properties to the coated film 25, improving winding properties. As a result, the coated film 25 is prevented from flapping or wrinkling as it is unwound from the film roll during extrusion processing, allowing for smooth unwinding, improving productivity and making it suitable for mass production. Therefore, the laminate film 10 of the present invention, which can contribute to reducing environmental impact, can be more widely used as a replacement for conventional laminate films and can contribute to the realization of an environmentally friendly, recycling-oriented society. [Example]

[0067] [Preparation of coated film] Using each material described below, the prepared coating agent was applied to the corona-treated surface of the substrate film, which had been corona-treated on one or both sides, at a wet rate of 4 g / m. 2 After the coating agent was applied, the substrate film was immediately placed in an oven at 120°C and dried for 5 seconds, and the coated films of Sample Examples 1 to 7 were obtained.

[0068] [Coating materials] A-1: Polyethyleneimine resin (Nippon Shokubai Co., Ltd.; "Epomin P-1000"), solid content 30 wt% A-2: Wax emulsion (Saiden Chemical Co., Ltd.; "Saibinol PN100"), solid content 24 wt% A-3: Nonionic surfactant (Kao Corporation; "Emulgen A-60")

[0069] [Base film] B-1: Biaxially oriented polypropylene film (Futamura Chemical Co., Ltd.; "FOR-AQ#20") B-2: Unstretched polypropylene film (Futamura Chemical Co., Ltd.; "FHK2#25") B-3: Biaxially oriented polypropylene film (Futamura Chemical Co., Ltd.; "FOS-BLBT#40") B-4: PET film (Futamura Chemical Co., Ltd.; "FE2001#12") B-5: Aluminum-deposited biaxially stretched polyester film (manufactured by Reiko Co., Ltd.; "Dialastar (registered trademark) FK#12")

[0070] [Prototype 1] In prototype 1, B-1, which has been corona treated on one side, is used as the base film, and A-1 and A-2 are mixed in a 1:1 ratio as the coating agent, with a solid content of 0.4% (coating amount 0.016 g / m). 2 ) and coated onto the corona-treated surface (one side) of the base film to form a coating layer.

[0071] [Prototype 2] In prototype 2, B-2, which has been corona treated on one side, is used as the base film, and A-1, A-2, and A-3 are mixed in a 1:1:0.5 ratio as the coating agent, with a solid content of 0.4% (coating amount of 0.016 g / m). 2 ) and coated onto the corona-treated surface (one side) of the base film to form a coating layer.

[0072] [Prototype 3] In prototype 3, B-3, which was corona-treated on both sides, was used as the base film, and A-1, A-2, and A-3 were mixed in a 1:1:0.5 ratio as the coating agent, with a solid concentration of 0.4% (coating amount 0.016 g / m). 2 ) and coated onto the corona-treated surfaces (both sides) of the base film to form a coating layer on both sides.

[0073] [Prototype 4] In prototype 4, B-5, which has been corona treated on one side, is used as the base film, and A-1 and A-2 are mixed in a 1:1 ratio as the coating agent, with a solid content of 0.4% (coating amount 0.016 g / m). 2 ) and coated onto the corona-treated surface (one side) of the base film to form a coating layer.

[0074] [Prototype 5] In prototype 5, B-6, which was corona treated on one side and vapor-deposited on the other side, was used as the base film, and A-1 and A-2 were mixed in a 1:1 ratio as the coating agent, with a solids concentration of 0.4% (coating amount 0.016 g / m). 2 ) and coated onto the corona-treated surface (one side) of the base film to form a coating layer.

[0075] [Prototype 6] In prototype 6, B-1, which had been corona-treated on one side, was used as the base film, and A-1 was used as the coating agent at a solids concentration of 0.2% (coating amount 0.008 g / m 2 ) and coated onto the corona-treated surface (one side) of the base film to form a coating layer.

[0076] [Prototype 7] In prototype 7, B-2, which has been corona treated on one side, is used as the base film, and A-1 and A-3 are mixed in a 1:0.5 ratio as the coating agent, with a solid content of 0.2% (coating amount 0.008 g / m). 2 ) and coated onto the corona-treated surface (one side) of the base film to form a coating layer.

[0077] The prepared coated films of Prototype Examples 1 to 7 were evaluated as follows for the physical properties of the film: shear blocking strength, haze, and film unwinding from the film roll (peeling noise, wrinkles). In the overall evaluation of the physical properties, if all properties were judged to be good, it was marked "○ (good)", and if any one property was judged to be poor, it was marked "× (unacceptable)". The results of each evaluation are shown in Table 1 below, along with the structure of each of Prototype Examples 1 to 7. In Table 1, the coating layer indicates the blending ratio of the coating agent materials used, and the base film indicates the type of film used.

[0078] [Shear blocking strength] For the coated films of prototypes 1 to 7, the shear blocking strength (N / 4cm) was measured, which is an index of anti-blocking performance. 2 In measuring the shear blocking strength, first, one side of the film was overlapped with the other side, assuming the film was in a rolled state (film roll), and a 4 cm test piece of the overlapped film was 2 A load of 1 N was applied to the sample and the sample was left at 40°C for 24 hours. Thereafter, the shear peel strength was measured using a tensile tester (Shimadzu Corporation; "Autograph AGS-X"), and the maximum strength when shear peeled at a tensile speed of 50 mm / min was taken as the shear blocking strength. The measurement result was 5.0 N / 4 cm. 2 Shear blocking strength was rated as good if:

[0079] [Haze] The haze (%), which is an index of transparency, was measured for the coated films of Prototype Examples 1, 2, 4, 6, and 7. Haze was measured in accordance with JIS K 7136 (2000) using a haze meter (Nippon Denshoku Industries Co., Ltd.; Haze Meter NDH-8000). A measurement result of 10% or less was evaluated as good for haze.

[0080] [Film handling status] For the coated films of Prototype Examples 1 to 3, 6, and 7, the film unwinding condition from the film roll was evaluated by the peeling noise when the film was unwound from the film roll and the wrinkles in the unwound film. The film unwinding conditions were a winding speed of 50 m / min and a tension of 5 N. The peeling noise during unwinding was measured using a sound level meter (RION Corporation; "NL-52"), and a rating of "× (unacceptable)" was given if a peeling noise of 30 dB or more was detected, or if the film was torn or broken, and a rating of "○ (good)" was given if neither occurred. Regarding wrinkles in the film, a rating of "× (unacceptable)" was given if one or more wrinkles were visually observed per A4 size film, and a rating of "○ (good)" was given if no wrinkles were observed.

[0081] [Table 1]

[0082] [Making laminated film] Among the coated films of Prototype Examples 1 to 7, the coated films of Prototype Examples 1 to 5, which had good physical properties, uncoated base films (B-1, B-2), and the sheet material described below were used as constituent materials for the laminate film to produce laminate films of Prototype Examples 11 to 18, each consisting of two layers (first and second layers) or three layers (first to third layers), according to the procedure described below. The coated films of Prototype Examples 1 to 5 were named C-1 to C-5, respectively.

[0083] [Sheet material] D-1: Linear low-density polyethylene film (Futamura Chemical Co., Ltd.; "LL-XMTN#30") D-2: Kraft paper for extrusion polyethylene, 55g / m 2 , thickness about 50 μm

[0084] [Prototype 11] Prototype example 11 is a laminated film obtained by extrusion processing, using C-1 (coated film) as the first layer and C-2 (coated film) as the second layer, with C-2 positioned on the coated layer side of C-1 with its coated layer facing C-1, and extruding polyethylene resin (Novatec LC604, manufactured by Japan Polyethylene Co., Ltd.) melted at 300°C between C-1 and C-2 using a T-die to a thickness of 10 μm to form a laminate layer, which was then pressed together with a cooling roll.

[0085] [Prototype 12] Prototype Example 12 uses C-1 (coated film) as the first layer, C-5 (coated film) as the second layer, and C-2 (coated film) as the third layer, with C-5 positioned on the coated layer side of C-1 with its coated layer facing C-1, and C-2 positioned with its coated layer facing C-5. Polyethylene resin (Novatec LC604, manufactured by Japan Polyethylene Co., Ltd.) melted at 300°C was extruded between C-1 and C-5, and between C-5 and C-2, each to a thickness of 10 μm, using a T-die to form laminate layers, which were then pressed together with a cooling roll to form a laminated film obtained by extrusion processing.

[0086] [Prototype 13] Prototype 13 is a laminated film that is the same as Prototype 11 except that C-4 (coated film) is used as the first layer and C-2 (coated film) is used as the second layer.

[0087] [Prototype 14] Prototype example 14 uses C-4 (coated film) as the first layer and C-3 (double-sided coated film) as the second layer, with C-3 positioned on the coated layer side of C-4, and polyethylene resin (Novatec LC604, manufactured by Japan Polyethylene Co., Ltd.) melted at 300°C was extruded between C-4 and C-3 using a T-die to a thickness of 10 μm to form a laminate layer, and the same polyethylene resin was extruded twice to a thickness of 10 μm onto the opposite side of the laminate layer between C-3 and C-4 to form a laminate layer, and the laminate layer was then pressed together with a cooling roll to form a laminate film obtained by extrusion processing.

[0088] [Prototype 15] Sample 15 is a laminated film that is identical to Sample 11 except that D-1 (linear low-density polyethylene film) is used as the second layer.

[0089] [Prototype 16] Sample 16 is a laminated film that is identical to Sample 11 except that D-2 (kraft paper for extruded polyethylene) is used as the second layer.

[0090] [Prototype 17] Prototype 17 is a laminated film that is identical to Prototype 11 except that it uses B-1 (biaxially oriented polypropylene film) as the first layer and B-2 (unoriented polypropylene film) as the second layer.

[0091] [Prototype 18] In prototype 18, B-1 (biaxially oriented polypropylene film) was used as the first layer, and B-2 (unoriented polypropylene film) was used as the second layer. The corona treated surface of B-1 was coated with a dry laminating adhesive at a rate of approximately 5 g / m. 2The laminate film was obtained by applying the adhesive to form a laminate layer, drying it, and then bonding it to the corona-treated surface of B-2, and then passing it through a roller to bring B-1 and B-2 into close contact with each other through dry lamination. The dry lamination adhesive used was prepared by mixing the base agent ("TM-250HV" manufactured by Toyo-Morton Co., Ltd.), the curing agent ("CAT-RT86L-60" manufactured by Toyo-Morton Co., Ltd.), and ethyl acetate (solvent).

[0092] The laminated films of prototypes 11 to 18 were evaluated for lamination strength and peelability when delaminated using an aqueous solution. If both lamination strength and peelability were good, the overall evaluation was given a "○ (good)"; if either was judged to be poor, it was given a "× (unacceptable)." The evaluation results are shown in Table 2 below, along with the configuration of each prototype 11 to 18.

[0093] [Laminate strength] Lamination strength (N / 15 mm) is an index of interlayer adhesion in laminated films and was measured according to JIS K 6854-3 (1999). Rectangular test pieces measuring 15 mm x 200 mm (width x length) were cut from the laminated films of Examples 11 to 18. The unlaminated portions were then stretched 180° vertically and fixed in the chucks of a tensile tester (Shimadzu Corporation, "AGS-X") and pulled vertically at a test speed of 200 mm / min to peel the laminated portions and determine the laminate strength. The laminate strength (N / 15 mm) was defined as the maximum peel force when peeled 100 mm. Measurement results of 2 N / 15 mm or greater were evaluated as "good," and results of less than 2 N / 15 mm were evaluated as "poor."

[0094] [Removability] The peelability of the laminated films of Prototype Examples 11 to 18 was evaluated assuming that the laminated films were peeled using an aqueous solution to separate the layers and recover the substrate films (B-1 to B-5). First, 5 mm square test pieces were cut from the laminated films of Prototype Examples 11 to 18 and their weights were measured. Next, 1 L of tap water containing 1% surfactant (Kao Corporation's "Emulgen 109") was prepared as the aqueous solution. The test pieces were immersed in the aqueous solution and stirred for 15 minutes in a Henschel laboratory mixer (Kawata Corporation's "SMP-2") (peeling treatment). After the treatment, the test pieces were recovered, washed with water, and dried in an oven to remove any adhering moisture. Peeled and unpeeled test pieces were then separated and weighed to calculate the percentage of peeled pieces from the laminated film. The peeling rate was used to evaluate the quality of the recovered substrate film, with a peeling rate of 90% or more being evaluated as "Excellent", a peeling rate of 50% or more being evaluated as "Good", and a peeling rate of less than 50% being evaluated as "Poor". If peeling was thought to have occurred that was not due to the peeling treatment, the film was evaluated as "Not acceptable" regardless of the peeling rate.

[0095] [Table 2]

[0096] [Results and Discussion] As can be seen from Table 2, the laminate films of prototypes 11 to 16 had both good lamination strength and peelability, the laminate film of prototype 17 had insufficient lamination strength and interlayer delamination occurred without peeling treatment, and the laminate film of prototype 18 showed no interlayer delamination and had strong lamination strength. Comparing prototypes 11 to 16 with prototypes 17 and 18, prototypes 11 to 16 used any of the coated films C-1 to C-5 as a constituent material, whereas prototypes 17 and 18 did not use a coated film as a constituent material.

[0097] In the laminate films of Prototype Examples 11, 13 to 16, a laminate layer was laminated on a coating film so that the coating layer was interposed between the base film and the laminate layer. Because the coating film had a coating layer containing a polyethyleneimine-based resin as an anchoring agent, it is believed that the base film and the laminate layer were properly bonded via the coating layer by extrusion processing in the laminate films of Prototype Examples 11, 13 to 16. In contrast, in Prototype Example 17, a polyethylene-based laminate layer was laminated by extrusion processing onto a polypropylene-based base film (B-1, B-2) without using a coating film, which is believed to have resulted in insufficient adhesion. Furthermore, in Prototype Example 18, the base films (B-1, B-2) and the laminate layer were bonded by dry lamination, which is believed to have resulted in sufficient adhesion without using a coating film. In addition, in prototype 12, laminate layers are laminated on both sides of the second layer coated film (C-5) which has a coating layer on one side, and it is believed that the required adhesion was achieved because the aluminum vapor-deposited surface has adhesive properties with the extruded polyethylene-based resin.

[0098] Furthermore, in coated films, the polyethyleneimine-based resin (anchor agent) contained in the coating layer is water-soluble, so the coating layer is dissolved by using an aqueous solution during the peeling process. Therefore, in the laminate films of Prototypes 11 to 16, the peeling process using an aqueous solution caused delamination between the substrate film and the laminate layer, with the coating layer interposed, which is thought to have enabled the substrate layer to be recovered from the laminate film. In particular, the laminate films of Prototypes 11, 13, 15, and 16, because of their thin thickness, were subjected to more bending in the stirring device, resulting in good peelability and allowing the substrate film to be recovered with high quality. In contrast, although Prototype 18 had good laminate strength as described above, the lack of a coated film likely prevented proper delamination.

[0099] As described above, in the laminate film, a coated film having a coating layer containing a polyethyleneimine-based resin is used, and by laminating a laminate layer on a base film via the coating layer, the base film and the laminate layer can be appropriately bonded together, and further, a peeling treatment using an aqueous solution can be used to easily peel the base film and the laminate layer from each other.

[0100] [Recyclability evaluation] Next, the recyclability of the recovered substrate film, peeled from the laminate film using a peeling treatment using an aqueous solution, was evaluated. The test specimen was the substrate film B-2, recovered by gravity separation of substrate B-4 from the laminate film of Prototype Example 13. The substrate film B-2 was placed in a twin-screw kneader (Imoto Manufacturing Co., Ltd.; "Simple Low-Cost Mixer (Iribus Blade) 1884"), melt-mixed at an extrusion temperature of 230°C, and then hot-pressed to produce a 500 μm-thick sheet. The sheet was cut into approximately 3 mm squares to prepare granular recycled raw material. 5% by weight of the resulting granular recycled raw material was dry-blended with 95% by weight of random polypropylene (Japan Polypropylene Corporation; "FX4EA"), melt-mixed, extruded using a T-die method, and cooled on a cooling roll to produce a 30 μm-thick unstretched polypropylene film (recycled film). As a comparative example, a 30 μm-thick unstretched polypropylene film was produced that did not contain the recycled material from the recovered substrate film. When the physical properties of the recycled film and the comparative film were compared, the recycled film had properties comparable to those of the comparative film, confirming that the base film recovered by the peeling treatment using an aqueous solution has good recyclability. [Industrial Applicability]

[0101] As described above, in the laminate film of the present invention, the substrate film and the laminate layer can be peeled off using an aqueous solution, allowing the substrate film to be easily recovered as a recycled material. Furthermore, the coated film used in the laminate film of the present invention can be smoothly unwound from a film roll, improving productivity and making it suitable for mass production. Therefore, environmentally friendly laminate films can be used more widely and are promising as a replacement for conventional laminate films. [Explanation of symbols]

[0102] 10,10A laminated film 20, 20a, 20b Base film 21, 21a, 21b, 21c Coating layer 25, 25A, 25B coated film 30, 30a, 30b Laminate layer

Claims

1. A laminate in which a laminate layer is formed on one side of a base film by extrusion processing, A laminated film in which the laminate can be peeled into the base film and the laminate layer by an aqueous solution, and recycled raw materials can be recovered, The substrate film is made of a thermoplastic resin and is a coated film having a coating layer coated with a coating agent containing a polyethyleneimine-based resin and a wax emulsion on one side on which the laminate layer is formed, The laminate layer is provided via the coating layer. A laminated film characterized by:

2. 2. The laminated film according to claim 1, wherein the solid content ratio of the polyethyleneimine resin to the wax emulsion in the coating agent is 3:2 to 2:

3.

3. The coating amount of the coating agent was 0.1 g / m on one side. ２ The laminated film according to claim 1, wherein:

4. 2. The laminated film according to claim 1, wherein the laminate strength between the coated film and the laminate layer is 2.0 N / 15 mm or more.

5. When the coated film is wound into a roll, the shear blocking strength between the coated layer side and the other side is 5.0 N / 4 cm ２ The laminated film according to claim 1, wherein:

6. 2. The laminated film according to claim 1, wherein the coating agent contains a nonionic surfactant.

7. The laminate film according to claim 1 , wherein the coating agent contains cellulose nanofibers.

8. The laminated film according to claim 1 , wherein the thermoplastic resin contains at least one of a plant-derived material and a recycled resin material.

9. A coated film used in a laminate in which a laminate layer is formed on one side of a base film by extrusion processing, The substrate film is made of a thermoplastic resin, and has a coating layer on one side where the laminate layer is formed, the coating layer being coated with a coating agent containing a polyethyleneimine-based resin and a wax emulsion; the coating layer is soluble in an aqueous solution; The laminate is configured so that the base film and the laminate layer can be peeled off by the aqueous solution. A coated film characterized by:

10. 10. The coated film according to claim 9, wherein the solid content ratio of the polyethyleneimine resin to the wax emulsion in the coating agent is 3:2 to 2:

3.

11. The coating amount of the coating agent was 0.1 g / m on one side. ２ The coated film according to claim 9, wherein:

12. A coated film having a lamination strength of 2.0 N / 15 mm or more when combined with the laminate layer formed by extrusion processing the coated film according to claim 9.

13. The coated film according to claim 9 has a shear blocking strength of 5.0 N / 4 cm between the coating layer side and the other side when wound into a roll. ２ The coated film is as follows:

14. The coated film according to claim 9, wherein the coating agent contains a nonionic surfactant.

15. The coated film according to claim 9 , wherein the coating agent contains cellulose nanofibers.

16. The coated film according to claim 9, wherein the thermoplastic resin contains at least one of a plant-derived material and a recycled resin material.

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