Laminate, recycled plastic substrate, molding material, and method for manufacturing molded product

Abstract

The present invention provides a laminate having a plastic substrate, a desorption layer, and a functional layer other than the desorption layer in this order, which achieves both blocking resistance and lamination strength of the laminate and desorption properties of the desorption layer, and which can suppress discoloration of the molding material and molded product obtained from recycled plastic substrates, as well as a method for manufacturing recycled plastic substrates, molding materials, and molded products. [Solution] A laminate having a first plastic substrate, a desorption layer (P), and a functional layer (F) other than the desorption layer adjacent to each other in this order, wherein the desorption layer (P) has the property of desorbing from the first plastic substrate by contact with a desorption liquid containing a basic compound, the desorption layer (P) contains a water-soluble urethane resin, and the film thickness of the desorption layer (P) is 0.1 μm or more and 1.0 μm or less.

Description

Technical Field

[0001] The present invention relates to a laminate having a release layer.

Background Art

[0002] In recent years, laminates made of plastic films, such as plastic products like packages (packaging materials) and plastic bottles, have been discarded or dumped into the ocean as garbage, contributing to environmental pollution problems. These plastic products are decomposed in seawater into sub-micron-sized fragments (microplastics) that float in the seawater. There is concern that such microplastics are ingested by marine organisms such as fish, concentrated in the organisms, and may also affect the health of seabirds and humans that ingest such marine organisms as food.

[0003] Examples of such plastic products include food packaging packages with a multi-layer structure using plastic films. In such food packaging packages, various plastic substrates such as polyester substrates, nylon substrates (NY), polypropylene substrates (PP), polyethylene substrates (PE), and film substrates including paper are used as the film base materials. These film base materials are printed with printing ink, bonded to other film base materials or heat-melted resin base materials through adhesives, etc., and then cut and heat-sealed to form packages. However, such food packaging packages with a multi-layer structure have a problem that they cannot be recycled as materials because a plurality of incompatible different materials are mixed.

[0004] Regarding the material recycling of such multi-layer laminates, for example, Patent Documents 1 and 2 disclose a technique for detaching a printed layer from a laminate having a release layer containing a water-soluble polyurethane resin having a predetermined acid value by treating the laminate with an alkaline aqueous solution, not only for a single-sided printed structure but also for a multi-layer structure.

[0005] Furthermore, Patent Document 3 discloses a technique for detaching a printed layer from a laminate by treating a laminate having a desorption layer containing a hydroxyl group-containing resin and an isocyanate-based curing agent with an alkaline aqueous solution. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-090627 [Patent Document 2] Japanese Patent Publication No. 2021-098294 [Patent Document 3] Patent No. 6777263 [Overview of the project] [Problems that the invention aims to solve]

[0007] Typically, for laminates intended for food packaging, a low amount of residual solvent is a required performance characteristic from the viewpoint of preventing deterioration of the flavor of the contents. However, in the laminates described in Patent Documents 1 to 3, polyurethane resin is used in the desorption layer, and in particular, when the resin has a polyester-based structure, the volatilization of ester-based solvents with a high structural similarity is suppressed, resulting in a problem of a large amount of residual solvent. In Patent Document 3, compounds having acidic groups, such as maleated rosin resin or acrylic resin with a high acid value, are used in the desorption layer. While the acidic groups provide high desorption properties, they have problems with water resistance and, furthermore, poor blocking resistance under high humidity and heat. Moreover, in the laminate of Patent Document 3, because the resin has many acidic groups, the skeleton of the resin itself becomes rigid, and there is a problem that the adhesion strength (laminate strength) after lamination cannot be maintained.

[0008] The object of the present invention is to provide a laminate having a plastic substrate, a desorption layer, and a functional layer other than the desorption layer in this order, which achieves both blocking resistance and lamination strength (referring to the lamination strength between plastic substrates when there are multiple plastic substrates) of the laminate, as well as desorption properties of the desorption layer, and which can suppress discoloration of the molding material and molded product obtained by recycling plastic substrates, as well as a method for manufacturing recycled plastic substrates, molding materials, and molded products. [Means for solving the problem]

[0009] The present invention relates to the following [1] to

[13] .

[0010] [1] A laminate having a first plastic substrate, a desorption layer (P), and a functional layer other than the desorption layer (F) adjacent to each other in this order, The desorption layer (P) has the property of being detached from the first plastic substrate by contact with a desorption solution containing a basic compound. The desorption layer (P) contains a water-soluble urethane resin, A laminate in which the thickness of the desorption layer (P) is 0.1 μm or more and 1.0 μm or less.

[0011] [2] The laminate according to [1], wherein the acid value of the water-soluble urethane resin is 10 mg KOH / g or more and 45 mg KOH / g or less.

[0012] [3] The laminate according to [1] or [2], wherein the weight-average molecular weight of the water-soluble urethane resin is 10,000 or more and 50,000 or less.

[0013] [4] A laminate having a first plastic substrate, a desorption layer (P), and a functional layer other than the desorption layer (F) adjacent to each other in this order, The desorption layer (P) has the property of being detached from the first plastic substrate by contact with a desorption solution containing a basic compound. The release layer (P) contains a water-soluble urethane resin, A laminate that satisfies both of the following conditions (1) and (2) when the thickness of the release layer (P) is A μm, the thickness of the functional layer (F) other than the release layer is B μm, and the total thickness of all plastic substrates contained in the laminate is C μm. (1) A / B is 0.1 or more and 0.6 or less (2) (A + B) / C × 10 is 0.4 or more and 1.5 or less

[0014] [5] The laminate according to any one of [1] to [4], further having an adhesive layer, A laminate that satisfies either of the following conditions (3) or (4) when the thickness of the release layer (P) is A μm, the thickness of the functional layer (excluding the adhesive layer) (F) other than the release layer is B μm, the total thickness of all plastic substrates contained in the laminate is C μm, and the thickness of the adhesive layer is D μm. (3) (A + D) / C × 10 is 0.25 or more and 1.0 or less (4) (A + B + D) / C × 10 is 0.5 or more and 1.5 or less

[0015] [6] The laminate according to any one of [1] to [5], wherein the content rate of the polyolefin resin contained in the plastic substrate in the laminate is 60% by mass or more based on the total mass of the plastic substrate in the laminate.

[0016] [7] The laminate according to any one of [1] to [6], further having a paper substrate.

[0017] [8] A method for producing a laminate, wherein a release layer forming material for forming the release layer (P) of the laminate according to any one of [1] to [7] is laminated on a first plastic substrate by printing or coating, and the mass of the organic solvent in the release layer forming material during printing or coating is 20% by mass or more and 90% by mass or less.

[0018] [9] A method for manufacturing a laminate according to [8], wherein the organic solvent is a water-soluble organic solvent with a boiling point of 150°C or lower.

[10] A method for producing a recycled plastic substrate, comprising a desorption step of contacting a laminate described in any of [1] to [7] with a desorption solution containing a basic compound at 30°C or higher, thereby desorbing a desorption layer (P) from a first plastic substrate.

[0019]

[11] A method for manufacturing a recycled plastic substrate according to

[10] , comprising a cutting step of cutting the laminate according to any one of [1] to [7] so that the maximum diameter is 1 to 50 mm, before the desorption step.

[0020]

[12] A method for producing a molding material, comprising the step of producing a pellet-shaped molding material by melting and kneading a recycled plastic substrate produced by the method for producing a recycled plastic substrate described in

[10] or

[11] at 140 to 290°C, and then cutting it.

[0021]

[13] A method for manufacturing a molded article, comprising the step of heat-molding a molding material manufactured by the manufacturing method described in

[12] . [Effects of the Invention]

[0022] The present invention provides a laminate having a plastic substrate, a desorption layer, and a functional layer other than the desorption layer in this order, which achieves both blocking resistance and lamination strength of the laminate and desorption properties of the desorption layer, and suppresses discoloration of the molding material and molded product obtained by recycling the plastic substrate, as well as a method for manufacturing a recycled plastic substrate, molding material, and molded product. [Modes for carrying out the invention]

[0023] The embodiments of the present invention will be described in detail below, but the descriptions of embodiments or requirements below are merely examples of embodiments of the present invention, and the present invention can be modified to the extent that the problem can be solved.

[0024] <Laminate> The laminate of the present invention is preferably used as a packaging material. Examples of applications for the packaging material include packaging bags, labels, containers, and lids. One embodiment of the laminate of the present invention is a laminate having a first plastic substrate, a desorption layer (P), and a functional layer (F) other than the desorption layer adjacent to each other in this order, wherein the desorption layer (P) has the property of desorbing from the first plastic substrate by contact with a desorption solution containing a basic compound, the desorption layer (P) contains a water-soluble urethane resin, and the film thickness of the desorption layer (P) is 0.1 μm or more and 1.0 μm or less. Furthermore, one embodiment of the laminate of the present invention is a laminate having a first plastic substrate, a desorption layer (P), and a functional layer (F) other than the desorption layer adjacent to each other in this order, wherein the desorption layer (P) has the property of desorbing from the first plastic substrate by contacting it with a desorption solution containing a basic compound, the desorption layer (P) contains a water-soluble urethane resin, and when the thickness of the desorption layer (P) is A μm, the thickness of the functional layer (F) other than the desorption layer is B μm, and the total thickness of all plastic substrates included in the laminate is C μm, the laminate satisfies both of the following conditions (1) and (2). (1) A / B is between 0.1 and 0.6 (2) (A+B) / C×10 is between 0.4 and 1.5

[0025] In this invention, "desorption" refers to the desorption of the desorption layer from the plastic substrate by dissolving or swelling with the desorption liquid.

[0026] Examples of the layer structure of a laminate include the following. However, the layer structure is not limited to those shown below. • First plastic substrate / Desorption layer (P) / Functional layer (F) (Printing ink layer) • First plastic substrate / desorption layer (P) / functional layer (F) (surface protective layer) • First plastic substrate / Desorption layer (P) / Functional layer (F) (Printing ink layer) / Surface protective layer • First plastic substrate / Desorption layer (P) / Functional layer (F) (Sealing layer) / Heat seal layer • First plastic substrate / Desorption layer (P) / Functional layer (F) (Printing ink layer) / Sealing layer / Heat seal layer • First plastic substrate / Desorption layer (P) / Functional layer (F) (Adhesive layer) / Second plastic substrate • First plastic substrate / Desorption layer (P) / Functional layer (F) (Printing ink layer) / Adhesive layer / Second plastic substrate • First plastic substrate / Desorption layer (P) / Functional layer (F) (Barrier layer) / Adhesive layer / Second plastic substrate • First plastic substrate / Desorption layer (P) / Functional layer (F) (Printing ink layer) / Barrier layer / Adhesive layer / Second plastic substrate • First plastic substrate / Desorption layer (P) / Functional layer (F) (Printing ink layer) / Barrier layer / Adhesive layer / Intermediate substrate / Adhesive layer / Second plastic substrate • First plastic substrate / Desorption layer (P) / Functional layer (F) (Printing ink layer) / Adhesive layer / Intermediate substrate (paper) / Adhesive layer / Second plastic substrate • Printing ink layer / Desorption layer / First plastic substrate / Desorption layer (P) / Functional layer (F) (Adhesive layer) / Intermediate substrate (paper) / Adhesive layer / Second plastic substrate

[0027] <First plastic substrate> The laminate of the present invention has a first plastic substrate. The first plastic substrate may be a single-layer plastic substrate or a substrate having multiple plastic layers. If the first plastic substrate consists of multiple layers, each layer may be bonded together via an adhesive layer or the like.

[0028] Examples of plastics included in the first plastic substrate include polyolefin resin, polyester resin, polyamide resin, polystyrene resin, vinyl chloride resin, vinyl acetate resin, ABS resin, acrylic resin, acetal resin, polycarbonate resin, polyvinyl alcohol resin, and cellulose-based plastics.

[0029] From the viewpoint of separating and recovering plastic substrates and reusing them as recycled plastics, it is more preferable that the first plastic substrate mainly contains polyolefin resin, which is easily recyclable. Examples of substrates mainly containing polyolefin resin include plastic substrates such as polyethylene (PE) and biaxially oriented polypropylene (OPP), as well as sealant substrates such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), acid-modified polyethylene, unoriented polypropylene (CPP), acid-modified polypropylene, and copolymerized polypropylene.

[0030] The thickness of the first plastic substrate is not particularly limited and may be appropriately selected depending on the application, but is preferably 5 to 1000 μm, and more preferably 10 to 500 μm. Furthermore, the plastic substrate may have a gas barrier layer or the like laminated on it. Examples of substrates to which the gas barrier layer is laminated include a film on which an organic resin composition such as polyvinyl alcohol or polyvinylidene chloride is laminated, or a vapor-deposited film having an inorganic vapor-deposited layer such as metal, silica, or alumina.

[0031] <Second plastic substrate, intermediate substrate> The laminate of the present invention may have a second plastic substrate as the outermost layer, and may also have an intermediate substrate. Preferred embodiments when the second plastic substrate and the intermediate substrate are plastic substrates can be described by referring to the description of the first plastic substrate above. As described later, the intermediate material may also preferably be paper.

[0032] From the viewpoint of reuse as recycled plastic, the plastic substrate in the laminate of the present invention preferably contains 60% by mass or more of the same type of resin, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Here, the same type of resin refers to a resin having the same or similar repeating units, and more specifically, the same type of resin is a resin composed of, for example, only polyolefin resin, only polyester resin, only polyamide resin, only polystyrene resin, only vinyl chloride resin, only vinyl acetate resin, only ABS resin, only acrylic resin, only acetal resin, only polycarbonate resin, only polyvinyl alcohol resin, or only cellulose-based plastic. Among these, the same type of resin is preferably a resin composed only of polyolefin resin, that is, the content of polyolefin resin in the plastic substrate in the laminate is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 100% by mass, based on the total mass of the plastic substrate in the laminate.

[0033] <Paper base material> The laminate of the present invention may also preferably further have a paper substrate as an intermediate substrate. The paper substrate is not particularly limited and any known material can be used, such as medium-grade paper, fine-grade paper, newsprint, various coated papers, backing paper, impregnated paper, cardboard, art paper, cast paper, kraft paper, coated cardboard, ivory paper, card stock, cup paper, cast paper, light-shielding paper, and paper substrates that have been surface-treated. The basis weight of the paper substrate is preferably 50 to 150 g / m². 2 More comfortably 55-120 g / m 2 More preferably 60-90 g / m 2 That is the case.

[0034] <Desorption layer (P)> The desorption layer (P) is positioned adjacent to the first plastic substrate and the functional layer (F) other than the desorption layer, and has the property of desorbing from the first plastic substrate by contact with a desorption liquid containing a basic compound, and contains a water-soluble urethane resin. The desorption layer (P) is formed by coating or printing a desorption layer forming material onto the first plastic substrate and curing (solidifying) it by drying or the like. In other words, the desorption layer is a layer of cured material of the desorption layer forming material.

[0035] In one embodiment of the laminate of the present invention, by having a film thickness of the desorption layer (P) of 0.1 μm or more and 1.0 μm or less, it is possible to significantly reduce residual solvent while achieving both blocking resistance and lamination strength of the laminate. The film thickness of the desorption layer (P) can be arbitrarily adjusted within the range of 0.1 μm or more and 1.0 μm or less, preferably 0.1 μm or more and 0.8 μm or less, more preferably 0.1 μm or more and 0.6 μm or less, and even more preferably 0.1 μm or more and 0.4 μm or less.

[0036] In one embodiment of the laminate of the present invention, when the thickness of the desorption layer (P) in the laminate is A μm, the thickness of the functional layer (F) other than the desorption layer is B μm, and the total thickness of all plastic substrates included in the laminate is C μm, it is preferable that both of the following conditions (1) and (2) are satisfied. This makes it possible to impart good desorption properties to the desorption layer and to significantly reduce residual solvent. (1) A / B is between 0.1 and 0.6 (2) (A+B) / C×10 is between 0.4 and 1.5

[0037] The A / B value in condition (1) is more preferably 0.1 to 0.5, and even more preferably 0.1 to 0.4. When the A / B value in condition (1) is 0.1 or higher, the desorption performance is good, and when it is 0.6 or lower, it contributes to reducing the amount of residual solvent and improving blocking resistance. The (A+B) / C×10 value in condition (2) is more preferably 0.4 to 1.35, and even more preferably 0.4 to 1.2. When the (A+B) / C×10 value in condition (2) is 0.4 or higher, the desorption performance is good, and when it is 1.5 or lower, it contributes to reducing the amount of residual solvent and improving blocking resistance.

[0038] In the case where the laminate of the present invention further comprises an adhesive layer, that is, a laminate comprising a first plastic substrate, a desorption layer (P), a functional layer other than the desorption layer (excluding the adhesive layer) (F), and an adhesive layer, it is preferable that either of the following conditions (3) or (4) is satisfied when the film thickness of the desorption layer (P) in the laminate is A μm, the film thickness of the functional layer other than the desorption layer (excluding the adhesive layer) is B μm, the film thickness of the adhesive layer is D μm, and the total thickness of all plastic substrates included in the laminate is C μm. This further provides good desorption properties to the desorption layer and enables a significant reduction in residual solvent. (3) (A+D) / C×10 is between 0.25 and 1.0 (4) (A+B+D) / C×10 is between 0.5 and 1.5

[0039] The value of (A+D) / C×10 in condition (3) is more preferably 0.3 or more and 0.9 or less, and even more preferably 0.3 or more and 0.8 or less. If the value of (A+D) / C×10 in condition (3) is 0.25 or more, the desorption performance is good, and if it is 1.0 or less, it contributes to reducing the amount of residual solvent and improving blocking resistance. The value of (A+B+D) / C×10 in condition (4) is more preferably 0.5 or more and 1.2 or less, and even more preferably 0.4 or more and 1.0 or less. If the value of (A+B+D) / C×10 in condition (4) is 0.4 or more, the desorption performance is good, and if it is 0.6 or less, it contributes to reducing the amount of residual solvent and improving blocking resistance.

[0040] (Water-soluble polyurethane resin (A)) The desorption layer (P) contains a water-soluble polyurethane resin (A) from the viewpoint of achieving both the functional expression and desorption properties of the functional layer (F). The water-soluble polyurethane resin (A) preferably contains acidic groups. The water-soluble polyurethane resin (A) may be a single type or a combination of two or more types. The content of the water-soluble polyurethane resin (A) is preferably 20 to 100% by mass, more preferably 30 to 90% by mass, and even more preferably 35 to 75% by mass, based on the total mass of the desorption layer (P). Note that "water-soluble" refers to a resin that can dissolve at a rate of 1 g or more in 100 g of water at 25°C.

[0041] The water-soluble polyurethane resin (A) is a polymer having urethane bonds, and it is preferable that it has a functional group that can be made water-soluble or a functional group that is a precursor thereof in part to ensure water solubility. Examples of water-soluble polyurethane resins (A) include urethane urea resins obtained by reacting a polyamine with an isocyanate group in a water-soluble polyurethane resin obtained by reacting a polyol with a polyisocyanate. Furthermore, from the viewpoint of desorption properties, it is preferable that the water-soluble polyurethane resin (A) has an acidic group, which is a functional group that can be made water-soluble. Examples of water-soluble polyurethane resins having an acidic group include a water-soluble polyurethane resin obtained by reacting a polyol having an acidic group with a polyisocyanate, a resin obtained by acid-modifying the hydroxyl groups in a water-soluble polyurethane resin obtained by reacting a polyol with a polyisocyanate, and a resin obtained by acid-modifying the amino groups in a urethane urea resin obtained by reacting a polyamine with an isocyanate group in a water-soluble polyurethane resin obtained by reacting a polyol with a polyisocyanate. Furthermore, as a water-soluble polyurethane resin having an acidic group, a resin obtained by reacting a polyol containing a hydroxy acid with a polyisocyanate may be used. By using a hydroxy acid as the polyol, an acid value derived from the carboxyl group can be imparted to the water-soluble polyurethane resin, thereby improving the desorption properties of the desorption layer (P). In addition, if the water-soluble polyurethane resin having an acidic group has an isocyanate group, a urea bond may be introduced by reacting a polyamine with a portion of the isocyanate group to form a urethane urea resin.

[0042] Polyol Polyols are a general term for compounds having at least two hydroxyl groups in a single molecule. The number-average molecular weight of polyols is preferably 500 to 10,000, more preferably 1,000 to 5,000. The above number-average molecular weight is calculated from the hydroxyl value of the polyol, and the hydroxyl value refers to the measurement value according to JIS K 0070. When the number-average molecular weight of the polyol is 500 or more, the flexibility of the desorption layer (P) is excellent, and the adhesion to the plastic substrate is improved. When the number-average molecular weight of the polyol is 10,000 or less, the blockage resistance of the laminate is excellent.

[0043] The content of polyol-derived constituent units is preferably 10 to 75% by mass, more preferably 15 to 70% by mass, and even more preferably 20 to 65% by mass, relative to the total amount of water-soluble polyurethane resin (A).

[0044] The polyol is not particularly limited, but it is preferable to include at least one polyol selected from the group consisting of polyester polyols, polyether polyols, and polycarbonate polyols. Furthermore, the polyol may also include other types such as dimerol, hydrogenated dimerol, and castor oil-modified polyol. In other words, the water-soluble polyurethane resin (A) preferably contains constituent units derived from at least one polyol selected from the group consisting of polyester polyols, polyether polyols, and polycarbonate polyols. It is more preferable that the resin contains constituent units derived from polyester polyols, as the ester bond sites of the polyester polyol undergo alkaline hydrolysis, thereby improving the desorption properties of the desorption layer (P). The content of constituent units derived from polyester polyol is preferably 5% by mass or more, more preferably 30% by mass or more, even more preferably 60% by mass or more, and particularly preferably 80% by mass or more, relative to the total amount of constituent units derived from polyol.

[0045] Hydroxy acid Polyols may contain hydroxy acids. The hydroxy acid refers to a compound that has both an active hydrogen group (hydroxyl group) and an acidic functional group in one molecule. The acidic functional group is a functional group that can be neutralized with potassium hydroxide when measuring the acid value, and specifically includes carboxyl groups and sulfonic acid groups, with carboxyl groups being preferred. Examples of hydroxy acids having such carboxyl groups include dimethylolalkanoates such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid.

[0046] Polyisocyanates The polyisocyanate is not particularly limited and can be selected from conventionally known polyisocyanates. Preferably, it contains a diisocyanate or triisocyanate, and more preferably, an aromatic, aliphatic, or alicyclic diisocyanate. These may be used alone or in combination of two or more.

[0047] Polyamines The polyamine is not particularly limited, but is preferably a diamine. Furthermore, a diamine having a hydroxyl group is preferred because it can introduce a hydroxyl group into the water-soluble polyurethane resin (A). Examples of diamines include ethylenediamine, propylenediamine, hexamethylenediamine, pentamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and p-phenylenediamine. Examples of diamines having a hydroxyl group include diamine 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypyropyrethylenediamine, di-2-hydroxypyropyrethylenediamine, and di-2-hydroxypropylethylenediamine.

[0048] The water-soluble polyurethane resin (A) preferably has hydroxyl groups, and in that case, its hydroxyl value is preferably 15 mg KOH / g or more, and more preferably 20 mg KOH / g. A hydroxyl value of 15 mg KOH / g or more for the water-soluble polyurethane resin (A) improves hydrophilicity and wettability to basic aqueous solutions, resulting in good desorption of the desorption layer (P). On the other hand, from the viewpoint of water resistance, the hydroxyl value of the water-soluble polyurethane resin (A) is preferably 30 mg KOH / g or less. The hydroxyl value may be a theoretical value calculated from the materials constituting the water-soluble polyurethane resin (A).

[0049] When the water-soluble polyurethane resin (A) has acidic groups, its acid value is preferably 5 to 70 mgKOH / g or more, more preferably 10 to 50 mgKOH or more, and even more preferably 15 to 40 mgKOH / g. When the acid value is 5 mgKOH / g or more, the swelling of the desorption layer (P) by the desorption liquid is promoted, and the desorption properties are further improved. When the acid value is 70 mgKOH / g or less, it contributes to the stability of the resin and also improves coating film performance such as blocking resistance and heat resistance. Similar to the hydroxyl value, the acid value may be a theoretical value calculated from the materials constituting the water-soluble polyurethane resin (A).

[0050] The weight-average molecular weight of the water-soluble polyurethane resin (A) is preferably 10,000 to 100,000, more preferably 15,000 to 70,000, and even more preferably 15,000 to 50,000. The molecular weight distribution (Mw / Mn) of the water-soluble polyurethane resin (A) is preferably 6 or less. Mw represents the weight-average molecular weight, and Mn represents the number-average molecular weight. When the above molecular weight distribution is 6 or less, the desorption of the desorption layer (P) is excellent, and the uniform coating of the desorption layer forming material may result in excellent drying properties and adhesion to the plastic substrate. Furthermore, the smaller the molecular weight distribution, i.e., the sharper the molecular weight distribution, the more uniformly the dissolution or desorption action by the desorption liquid occurs, and the better the desorption of the desorption layer (P) may be. The above molecular weight distribution is more preferably 1.5 to 5, and even more preferably 1.2 to 4.0. In this invention, Mw, Mn, and molecular weight distribution (Mw / Mn) are polystyrene-equivalent values ​​determined by gel permeation chromatography (GPC).

[0051] The water-soluble polyurethane resin (A) may contain amino groups. If the water-soluble polyurethane resin (A) contains amino groups, its amine value is preferably 0.1 to 20 mg KOH / g, and more preferably 1 to 10 mg KOH / g. When the amine value is within the above range, excellent adhesion to the substrate may be observed. The amine value may be a theoretical value calculated from the materials constituting the water-soluble polyurethane resin (A).

[0052] <Additives> The desorption layer (P) may contain additives. Known additives include, for example, dispersants, wetting agents, adhesion aids, leveling agents, defoamers, antistatic agents, viscosity modifiers, metal chelates, trapping agents, antiblocking agents, and wax components other than those listed above.

[0053] The arithmetic surface roughness Ra of the desorption layer (P) on the surface adjacent to the functional layer (F) other than the desorption layer is preferably less than 5.0 μm. More preferably, the arithmetic surface roughness Ra is less than 3.0 μm, and it is even more preferable as it approaches the arithmetic surface roughness of the first plastic substrate. As the arithmetic surface roughness Ra of the desorption layer (P) decreases, the smoothness of the desorption layer surface improves, so the upper functional layer (F) is formed more uniformly, and the function of the functional layer (F) tends to improve.

[0054] <Desorption layer forming material> In this specification, a material for forming a desorption layer (P) by curing (solidification) is referred to as a desorption layer forming material. The desorption layer (P) is formed, for example, by printing or coating the desorption layer forming material and then curing it. The desorption layer forming material can take the form of a varnish, for example, in which a resin or additive that forms the desorption layer (P) is dissolved in a solvent such as water or an organic solvent, or in the form of a dispersion in which insoluble particles such as pigments or waxes, or emulsified resins are dispersed in the varnish. Furthermore, extender pigments can be used as appropriate to impart resistance to the desorption layer forming material. Preferably, the extender pigment is silica, and more preferably, hydrophilic silica. Using silica can further improve the blocking resistance and abrasion resistance after coating. The silica content is preferably 0.1 to 10% by mass, more preferably 1.0 to 8% by mass, and even more preferably 2.0 to 5% by mass, based on the total amount of the desorption layer.

[0055] Preferably, the organic solvent content of the desorption layer forming material is 20% by mass or more and 90% by mass or less relative to the total mass of the desorption layer forming material when printed or coated. If it is 20% by mass or more, the surface tension of the desorption layer forming material decreases, improving wettability to the plastic substrate, forming a uniform desorption layer, and improving deinking properties. Furthermore, the drying properties improve, which also improves curing properties, suppresses the absorption of organic solvent contained in the functional layer and adhesive layer, and reduces residual solvent. If it is 90% by mass or less, the solubility of water-soluble urethane resin is good, and the suitability for printing and coating is good. It is even more preferable that the mass of organic solvent in the desorption layer forming material be 40% by mass or more and 80% by mass or less, and even more preferable that it be 50% by mass or more and 70% by mass or less.

[0056] The organic solvent contained in the above desorption layer forming material is preferably a water-soluble organic solvent with a boiling point of 150°C or lower. A boiling point of 150°C or lower improves drying properties. Furthermore, water-soluble organic solvents are easily mixed with water, resulting in good solubility of water-soluble urethane resins. Examples of such solvents include alcohols such as acetone, methanol, and ethanol, ethers such as tetrahydrofuran, and glycols such as propylene glycol monomethyl ether. Here, water solubility means that 1 ml of the organic solvent is miscible when mixed with 100 ml of water.

[0057] The ratio of solid content to the total mass of the desorption layer forming material can be adjusted as appropriate depending on the printing or coating method, but from the viewpoint of suitability for printing or coating, it is preferably 1 to 99% by mass, more preferably 5 to 90% by mass.

[0058] The desorption layer forming material may further contain a crosslinking agent, preferably one or more selected from the group consisting of isocyanate crosslinking agents, carbodiimide crosslinking agents, silane crosslinking agents, and hydrazide crosslinking agents. These crosslinking agents crosslink within the desorption layer formed by coating or printing, improving durability to ethyl acetate and isopropyl alcohol, thereby further improving the haze values ​​of the ethyl acetate and isopropyl alcohol solutions of the desorption layer. These crosslinking agents can be mixed in any proportion immediately before coating or printing the desorption layer forming material and used.

[0059] (Isocyanate crosslinking agent) The isocyanate crosslinking agent is not particularly limited and can be selected from those conventionally known. Examples of isocyanate crosslinking agents include aliphatic polyisocyanates or aromatic aliphatic polyisocyanates. These may be used alone or in combination of two or more.

[0060] As the aliphatic polyisocyanate, well-known aliphatic diisocyanates, alicyclic diisocyanates, or derivatives thereof can be used. Aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate, and other aliphatic diisocyanates; 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate Examples include alicyclic diisocyanates such as tomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanate methyl)cyclohexane, and 1,3-bis(isocyanate methyl)cyclohexane; and polyisocyanates such as allophanate-type, nurate-type, biuret-type, and adduct-type derivatives or complexes thereof derived from the above diisocyanates.

[0061] As the aromatic polyisocyanate, well-known aromatic diisocyanates or their derivatives can be used. Examples of aromatic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, or allophanate-type, nurate-type, biuret-type, or adduct-type derivatives or complexes thereof derived from the above diisocyanates.

[0062] Preferably, the polyisocyanate is an adduct-type polyisocyanate (hereinafter referred to as adduct), a biuret-type polyisocyanate (hereinafter referred to as biuret-type polyisocyanate) or an isocyanurate-type polyisocyanate (hereinafter referred to as isocyanurate-type polyisocyanate) of tolylene diisocyanate (hereinafter referred to as TDI), diphenylmethane diisocyanate (hereinafter referred to as MDI), or hexamethylene diisocyanate (hereinafter referred to as HDI), and more preferably, a trimethylolpropane adduct (HDI-TPM), a biuret-type polyisocyanate, or an isocyanurate-type polyisocyanate derived from hexamethylene diisocyanate.

[0063] (Carbodiimide crosslinking agent) The carbodiimide crosslinking agent is not particularly limited and can be selected from those conventionally known, such as monocarbodiimide compounds or polycarbodiimide compounds. These may be used alone or in combination of two or more.

[0064] Polycarbodiimide compounds are produced by known methods, for example, by heating mono, di, and triisocyanate compounds in a non-reactive organic solvent in the presence of a suitable catalyst, such as 3-methyl-1-phenyl-2-phosphorate oxide, and converting the isocyanate groups to carbodiimide groups by decarboxylation. Organic isocyanates used as raw materials for the synthesis of polycarbodiimide compounds include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, or mixtures thereof, such as 1,5-naphthylene diisocyanate, 4,4-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 4,4-dibenzyli isocyanate, dialkyldiphenylmethane diisocyanate, and tetraalkyldiphenylmethane diisocyanate. Examples include 1,3-phenylenediisocyanate, 1,4-phenylenediisocyanate, tolylenediisocyanate, butane-1,4-diisocyanate, hexamethylenediisocyanate, 2,2,4-trimethylhexamethylenediisocyanate, lysinediisocyanate, cyclohexane-1,4-diisocyanate, xylylenediisocyanate, isophoronediisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3-bis(isocyanate-methyl)cyclohexane, methylcyclohexanediisocyanate, n-tetramethylxylylenediisocyanate, and dimethylyldiisocyanate. These carbodiimide compounds can be used individually or in combination of two or more.

[0065] (Silane crosslinking agent) The silane crosslinking agent is not particularly limited and can be selected from those conventionally known, such as epoxy alkoxysilanes, amino alkoxysilanes, and isocyanate alkoxysilanes. These may be used individually or in combination of two or more.

[0066] (Hydrazide crosslinking agent) The hydrazide crosslinking agent is not particularly limited and can be selected from those conventionally known, such as adipic acid dihydrazide, sebacate acid dihydrazide, and isophthalic acid dihydrazide. These may be used alone or in combination of two or more.

[0067] The crosslinking agent content is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1 to 25% by mass, relative to the total solid content in the desorption layer forming material. When the crosslinking agent content is within the above range, crosslinking is possible while maintaining the flexibility of the desorption layer, thus exhibiting good adhesion between the desorption layer and the plastic substrate, and contributing to improved laminate strength. The laminate may also be aged to allow the crosslinking agent to react sufficiently.

[0068] <Functional Layer (F)> The functional layer (F) is a layer other than the desorption layer (P) and is a layer that imparts various functions to the laminate. The functional layer (F) is formed in contact with the aforementioned desorption layer (P). The functional layer (F) is separated from the first plastic substrate when the aforementioned desorption layer (P) is desorbed by the desorption liquid. This yields a plastic suitable for recycling. The functional layer can be formed, for example, by applying or printing a functional layer forming material onto the desorption layer (P) on the plastic substrate, and then drying or curing it.

[0069] Functional layers (F) can specifically include printing ink layers, adhesive layers, sealing layers, heat-sealing layers, barrier layers, surface protection layers, and release layers. Functional layers are used to impart functions necessary for the application of the laminate, such as aesthetic appeal and processability, and the effects of the present invention are not particularly limited to the type of function.

[0070] <Printing ink layer> The printing ink layer may be colored or colorless, and preferably contains known colorants used in printing inks and paints. The colorants are not particularly limited, and may include organic pigments, inorganic pigments, dyes, as well as metal powders that provide metallic luster and near-infrared absorbing materials.

[0071] Known colorants include, but are not limited to, organic pigments such as soluble azo, insoluble azo, azo, phthalocyanine, halogenated phthalocyanine, anthraquinone, anthancerone, dianthaquinonyl, anthrapyrimidine, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethine azo, flavanthrone, diketopyrrolopyrrole, isoindoline, indanthrone, and carbon black. More specifically, suitable organic pigments include, for example, carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthal yellow, chromophthal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigobordeaux, thioindigomagenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments. However, these are not limited to these, and any CI pigments listed in the color index or those listed by generic names can be used as appropriate as colorants. In particular, since the desorbent liquid used in the method for producing recycled plastics of the present invention may contain basic compounds, alkali-resistant pigments that do not leach even when the desorbent liquid is a basic aqueous solution are preferred. Alkali-resistant pigments make it easier to reuse basic aqueous solutions by preventing pigment leaching. Here, an alkali-resistant pigment refers to a pigment in which, when 1 g of pigment is added to 100 g of a 2% sodium hydroxide aqueous solution, and after stirring, the pigment-derived components precipitate when left to stand for 24 hours, but the aqueous solution itself does not retain its color. Examples of alkali-resistant pigments include inorganic pigments, CI Pigment Blue 15, CI Pigment Yellow 83, and CI Pigment Red 146. The content of the organic pigment is preferably 5 to 50% by mass, more preferably 6 to 30% by mass, and even more preferably 7 to 25% by mass, in the total amount of the printed layer.

[0072] Examples of inorganic pigments include white inorganic pigments such as titanium dioxide, zinc oxide, zinc sulfide, and chromium oxide; and extender pigments such as silica, barium sulfate, kaolin, clay, calcium carbonate, magnesium carbonate, zinc oxide, and zirconium oxide. Among the inorganic pigments, titanium dioxide is preferred. Titanium dioxide is preferred in terms of its white color, coloring ability, opacity, chemical resistance, and weather resistance, and from the viewpoint of printing performance, titanium dioxide treated with silica and / or alumina is preferred. As an extender pigment, silica is preferred, and hydrophilic silica is more preferred. By using silica, blocking properties and abrasion resistance after coating can be improved. The silica content is preferably 0.1 to 10% by mass of the total printed layer, more preferably 1.0 to 8% by mass, and even more preferably 2.0 to 5% by mass. The content of inorganic pigments is preferably 20 to 80% by mass, and more preferably 30 to 75% by mass, in the total amount of the printed layer when the pigment is titanium dioxide. Furthermore, when the pigment is one or more selected from the group consisting of inorganic pigments other than titanium dioxide, extender pigments, and organic pigments, the total content of these pigments is preferably 0.5 to 60% by mass, and more preferably 10 to 50% by mass, in the total amount of the printed layer.

[0073] <Method for manufacturing laminates> The manufacturing method for each of the above embodiments of the laminate preferably includes a desorption layer forming step of forming a desorption layer (P) on a plastic substrate using a desorption layer forming material, and a functional layer forming step of forming a functional layer (F) on the desorption layer (P) using a functional layer forming material. In this manufacturing method, the method of forming the desorption layer (P) and the functional layer is not particularly limited. For example, when the desorption layer (P) and the functional layer are formed by printing, the desorption layer forming material and the functional layer forming material can be printed and formed using known methods such as offset printing, gravure printing, flexographic printing, and inkjet printing. Since the laminate of the present invention is preferably used as a packaging material, it is preferable to use offset printing, gravure printing, or flexographic printing, which have excellent processing speeds, from the viewpoint of manufacturing efficiency, and it is even more preferable to use gravure printing or flexographic printing.

[0074] The manufacturing method for the above-mentioned laminate can be an offline method or an in-line method. The offline method is a method that inserts a laminate discharge process between the desorption layer formation process and the functional layer formation process. That is, for example, a plastic substrate is fed from the paper feed section of a coating machine or printing machine, and after the desorption layer formation process, a laminate consisting of the plastic substrate and the desorption layer is discharged from the paper discharge section in a discharge process. Then, the laminate is fed again from the paper feed section of the same or a different coating machine or printing machine, and after the functional layer formation process, the laminate is discharged from the paper discharge section and recovered. The in-line method is a method in which the desorption layer formation process and the functional layer formation process are performed continuously in the same coating machine or printing machine without an intermediate laminate discharge process. That is, for example, a plastic substrate is fed from the paper feeding section of the coating machine or printing machine, the desorption layer formation process is performed, and then the functional layer formation process is performed continuously in a separate unit of the same coating machine or printing machine, and the laminate is discharged and recovered from the paper discharge section. The offline method allows for printing the desorption layer and functional layer using different methods, offering the advantage of selecting materials for the desorption layer and functional layer to match the required quality of the laminate. However, it requires two or more discharge processes, resulting in lower efficiency. On the other hand, the in-line method allows for the production of the laminate in a single discharge process, offering superior manufacturing efficiency. In this invention, it is preferable to create a laminate by coating using an in-line method, but a laminate can also be created using an offline method.

[0075] In the method for manufacturing the laminate, it is also preferable to include a drying step after the desorption layer formation step and the functional layer formation step. In the drying step, it is preferable to use a dryer, and the type of dryer, temperature, and airflow rate should be appropriately selected according to the type and thickness of the plastic substrate, and the desorption layer forming material and / or functional layer forming material. Furthermore, when using, for example, UV / EB curable desorption layer forming materials and / or functional layer forming materials, it is preferable to include a curing step using a UV lamp or EB lamp instead of a drying step. In addition, to improve drying or curing ability, a preheating method may be appropriately used in which the plastic substrate supplied from the paper feed section, or a laminate consisting of a plastic substrate and a desorption layer, is passed through a dryer before the desorption layer forming step and the functional layer forming step.

[0076] The processing speed in the manufacturing method of the laminate can be appropriately selected depending on the coating method, the type and thickness of the plastic substrate, and the desorption layer forming material and / or the functional layer forming material. For example, in the case of gravure printing and flexographic printing, the processing speed is preferably 50 m / min or more, and more preferably 70 m / min or more.

[0077] <Method for manufacturing recycled plastic substrates> A method for producing a recycled plastic substrate includes a desorption step of contacting the laminate of the present invention with a desorption liquid at 30°C or higher to desorb the desorption layer (P) from the first plastic substrate, and a recovery step of recovering the first plastic substrate after the desorption step to obtain a recycled plastic substrate.

[0078] <Desorption process> The desorption step preferably involves contacting the laminate of the present invention with a desorption liquid at 30°C or higher to swell and / or dissolve the desorption layer (P) adjacent to the first plastic substrate, thereby desorbing it. After the desorption step, the first plastic substrate can be recovered to obtain a recycled plastic substrate. Examples of the eluent include water, a basic aqueous solution, water containing an organic solvent, and an organic solvent. The eluent may also contain additives such as surfactants. Of these, a basic aqueous solution obtained by dissolving a basic compound in water can be used particularly suitably as a desorbing agent.

[0079] (Basic compounds) The basic compound can be any compound whose desorption solution, prepared by dissolving it in water, swells and / or dissolves the desorption layer (P). Examples include metal hydroxides such as sodium hydroxide and amine compounds such as ammonia. Among these, metal hydroxides that are strongly alkaline in small amounts and have good desorption performance are preferred, and sodium hydroxide, which has high solubility in water, is particularly preferred. The concentration of the basic compound can be appropriately adjusted according to the strength of basicity, solubility, and temperature of the basic compound. For example, for an aqueous solution of sodium hydroxide at 70°C, the concentration is preferably 0.1% to 10.0% by mass, more preferably 0.5% to 5.0% by mass, and even more preferably 1.0% to 3.0% by mass. The temperature of the aqueous basic solution is preferably 30°C to 80°C, and even more preferably 40°C to 70°C.

[0080] The desorbent liquid may further contain a surfactant and / or an antifoaming agent to improve desorbing performance. The surfactant preferably contains at least one selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants and / or nonionic surfactants, and more preferably contains a nonionic surfactant.

[0081] These surfactants may be used individually or in combination of two or more. The total content of surfactants in the eluent is preferably in the range of 0.1 to 10% by mass, and more preferably in the range of 0.3 to 5% by mass, based on 100% by mass of the eluent. A total surfactant content of 0.1% by mass or more is preferable because it provides excellent deinking and re-adhesion properties, and a total surfactant content of 10% by mass or less is preferable from the viewpoint of suppressing foaming.

[0082] [Anionic surfactants] Examples of anionic surfactants include sulfonic acid-based anionic surfactants, sulfate ester-based anionic surfactants, carboxylic acid-based anionic surfactants, and phosphate ester-based anionic surfactants.

[0083] [Cationic surfactants] Examples of cationic surfactants include alkylamine salts and quaternary ammonium salts. Specifically, stearylamine acetate, trimethyl coconut ammonium chloride, trimethyl beef tallow ammonium chloride, dimethyl dioleyl ammonium chloride, methyl oleyl diethanol chloride, tetramethyl ammonium chloride, laurylpyridinium chloride, laurylpyridinium bromide, laurylpyridinium disulfate, cetylpyridinium bromide, 4-alkyl mercaptopyridine, poly(vinylpyridine)-dodecyl bromide, dodecylbenzyltriethylammonium chloride, etc. can be used.

[0084] [Amphoteric surfactants] Examples of amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine, polyoctyl polyaminoethylglycine, and imidazoline derivatives.

[0085] [Nonionic surfactants] The nonionic surfactant is not particularly limited, but is preferably an alkylene oxide adduct to which alkylene oxide (hereinafter also referred to as AO) has been added. More preferably, it is a compound obtained by adding alkylene oxide to alcohols having active hydrogen, a compound obtained by adding alkylene oxide to amines, or a compound obtained by adding alkylene oxide to fatty acids. The above addition may be random addition or block addition. The number of carbon atoms in the alkylene oxide is preferably 2 to 4. More preferably, the nonionic surfactant is an alcohol-based nonionic surfactant obtained by adding an alkylene oxide having 2 to 4 carbon atoms to an alcohol.

[0086] [Antifoaming agent] The defoaming liquid preferably further contains an antifoaming agent. Antifoaming agents generally have extremely high lipophilicity and an HLB value in the range of 1 to 3. By using an antifoaming agent in combination with the surfactant described above, good defoaming properties can be achieved without reducing defoaming and readhesion properties, and foaming caused by the surfactant can be suppressed. Examples of the above-mentioned defoaming agents include silicone-based compounds and non-silicone-based compounds.

[0087] The contact time of the laminate with the desorbing liquid is preferably in the range of 1 minute to 24 hours, more preferably 1 minute to 12 hours, and even more preferably 1 minute to 6 hours. When the laminate is in contact with the desorbing liquid, it is preferable to stir or circulate the laminate to improve the desorbing efficiency of the desorbing layer. In this case, the rotation speed is preferably 80 to 5000 rpm, more preferably 80 to 4000 rpm.

[0088] The content of the laminate when it is brought into contact with the desorption liquid is preferably 0.1% to 15% by mass, more preferably 1% to 12% by mass, even more preferably 1.5% to 10% by mass, and still more preferably 2% to 8% by mass, relative to the total mass of the desorption liquid. A content of 0.1% by mass or more is preferable from the viewpoint of processing efficiency, and a content of 10% by mass or less is preferable from the viewpoint of desorption performance.

[0089] <Cutting process> The method for manufacturing recycled plastic may also preferably include a cutting step, in which the laminate of the present invention is cut before the desorption step. Cutting is a step of fragmenting the shape of the present invention, and includes cutting by crushing. The cutting method is not particularly limited, and examples include using a jaw crusher, impact crusher, cutter mill, stamp mill, ring mill, roller mill, jet mill, or hammer mill. The maximum diameter of the laminate after cutting is preferably 1 to 50 mm, more preferably 3 to 45 mm, and even more preferably 5 to 40 mm. By cutting the laminate so that the maximum diameter is 1 to 50 mm, the efficiency of the washing, dewatering, and drying steps is improved by increasing the surface area of ​​the laminate, and the homogenization of the molten resin is further promoted, resulting in a higher quality recycled plastic.

[0090] <First cleaning step> The method for manufacturing recycled plastic may also preferably include a first washing step of washing the laminate of the present invention before the desorption step. The first washing step may be performed before, simultaneously with, or after the cutting step, but it is preferable to perform it simultaneously with the cutting step by a method such as wet crushing.

[0091] <Second cleaning process> The method for manufacturing recycled plastic may also preferably include a second washing step after the detachment step, in which the recovered first plastic substrate is washed. Washing methods may include batch or continuous washing, and water, detergent, neutralizing agent, alkaline aqueous solution, etc., can be used for washing.

[0092] (Dehydration and drying) After the second washing step, it is preferable to perform dewatering and / or drying. Centrifugal dewatering is preferred as the dewatering method, and hot air drying is preferred as the drying method. By performing dewatering and / or drying, foaming during the manufacturing of the molding material, which will be described later, can be suppressed, and high-quality molding material and molded articles can be obtained.

[0093] <Method for manufacturing molding materials> Molding materials can be manufactured from the above-mentioned recycled plastic substrate. The manufacturing of the molding material preferably involves, for example, melting and kneading the recycled plastic substrate in an extruder equipped with a screw, and then cooling it to 40°C or below. More specifically, the process preferably includes the steps of supplying the recycled plastic substrate from a supply port, melting and kneading the recycled plastic substrate supplied from the supply port in a melting and kneading section, and then discharging the molding material melted and kneaded in the melting and kneading section from a discharge section and cooling it to obtain the molding material. The shape of the molding material is not particularly limited and can be rod-shaped, granular, cubic, rectangular, irregular, etc., but it is preferable to cut it into a pellet shape.

[0094] From the viewpoint of obtaining a uniform molding material, the temperature during melt mixing is preferably 140 to 290°C, more preferably 145 to 280°C, and even more preferably 150 to 270°C. It is also preferable to add a compatibilizer during melt mixing.

[0095] [Masterbatch] A preferred method for manufacturing the molding material is to mix the recycled plastic and the masterbatch by melt-kneading. The masterbatch is not particularly limited as long as it is compatible with recycled plastics, and generally, a mixture of a thermoplastic resin such as polyethylene resin or polypropylene resin and a colorant can be used. The thermoplastic resin included in the masterbatch may be used alone or in combination of two or more types. The masterbatch may contain alkali metal, alkaline earth metal, or zinc metal soaps, hydrotalcite, nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, antistatic agents, flame retardants such as halogenated, phosphorus-based, or metal oxides, lubricants such as ethylenebisalkylamide, antioxidants, ultraviolet absorbers, and fillers, to the extent that they do not impair the effects of the present invention.

[0096] <Method for manufacturing molded articles> A molded body can be obtained by heat-molding the molding material obtained by the above manufacturing method. The heat-molding method is not particularly limited and examples include injection molding, extrusion molding, blow molding, and compression molding. The molding material produced using the recycled plastic obtained by the present invention's method for producing recycled plastic is of high quality because the functional layer (F) and other components are separated by the desorption layer (P), and can be used in a variety of fields, such as home appliances, stationery, automobile parts, toys, sporting goods, medical supplies, and building or construction materials. [Examples]

[0097] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, parts and % refer to parts by mass and mass %, respectively, unless otherwise noted.

[0098] <Molecular weight and molecular weight distribution> The weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were measured by GPC (gel permeation chromatography) and determined as converted molecular weights using polystyrene as a standard substance. The measurement conditions are shown below. GPC device: Showa Denko Shodex GPC-104 Columns: The following columns were used, connected in series. Two Shodex LF-404 tubes manufactured by Showa Denko. Showa Denko Shodex LF-G Detector: RI (Differential Refractometer) Measurement conditions: Column temperature 40°C Eluent: Tetrahydrofuran Flow rate: 0.3mL / min

[0099] <Acid value, hydroxyl value> The acid value and hydroxyl value were measured according to the method described in JIS K 0070 (1992).

[0100] <Synthesis of resins for desorption layer forming materials> [Synthesis Example 1-1] (Polyurethane Resin A1) In a reactor equipped with a reflux condenser, dropping funnel, gas inlet tube, stirrer, and thermometer, 108.6 parts of PPA (a polyester polyol with a number average molecular weight of 2,000, consisting of a polycondensate of propylene glycol and adipic acid), 40.7 parts of PEG (a polyether polyol with a number average molecular weight of 2,000, consisting of polyethylene glycol), 28.3 parts of DMPA (2,2-dimethylolpropanoic acid), 105.7 parts of IPDI (isophorone diisocyanate), and 200 parts of NPAC (n-propyl acetate) were charged while introducing nitrogen gas. The mixture was reacted at 90°C for 5 hours to obtain a prepolymer solution having isocyanate groups at the ends. Next, a mixture of 16.7 parts AEA (2-(2-aminoethylamino)ethanol) and 150 parts IPA (isopropyl alcohol) was added dropwise to the resulting urethane prepolymer solution at room temperature over 60 minutes. Then, 10.0 parts of 28% aqueous ammonia and 690 parts of deionized water were gradually added to neutralize the carboxyl groups in the resin, thereby making it water-soluble. Next, NPAC and IPA were removed by vacuum distillation to obtain an aqueous solution of polyurethane resin A1 with a solid content of 30%, a mass-average molecular weight of 32,000, Mw / Mn = 3.3, and an acid value of 39.3 mgKOH / g. However, the acid value of A1 is the value before neutralization.

[0101] [Synthesis Example 1-2] (Polyurethane Resin A2) In a reactor equipped with a reflux condenser, dropping funnel, gas inlet tube, stirrer, and thermometer, 198.7 parts of PMPA (a polyester polyol with a number average molecular weight of 2,000 consisting of 3-methyl-1,5-pentanediol and adipic acid), 29.0 parts of DMPA (2,2-dimethylolpropanoic acid), 105.3 parts of IPDI (isophorone diisocyanate), and 81.4 parts of NPAC (n-propyl acetate) were charged while introducing nitrogen gas. The mixture was reacted at 90°C for 5 hours to obtain a prepolymer solution having isocyanate groups at the ends. Next, a mixture of 16.5 parts AEA (2-(2-aminoethylamino)ethanol), 1.0 part dibutylamine (hereinafter referred to as "DBA"), and 750.3 parts IPA (isopropyl alcohol) was added dropwise to the resulting urethane prepolymer solution at room temperature over 60 minutes. Then, 14.28 parts of 28% aqueous ammonia and 803.5 parts of deionized water were gradually added to neutralize the carboxyl groups in the resin, thereby making it water-soluble. Next, NPAC and IPA were removed by vacuum distillation to obtain an aqueous solution of polyurethane resin A2 with a solid content of 30%, a mass-average molecular weight of 25,000, Mw / Mn = 3.0, and an acid value of 34.6 mgKOH / g. However, the acid value of A2 is the value before neutralization.

[0102] [Synthesis Example 1-3] (Polyurethane Resin A3) In a reactor equipped with a reflux condenser, dropping funnel, gas inlet tube, stirrer, and thermometer, 139.1 parts of PCL2000 (polycarbonate diol with a number average molecular weight of 2000), 36.9 parts of PEG (polyether polyol made of polyethylene glycol with a number average molecular weight of 2000), 35.5 parts of DMPA (2,2-dimethylolpropanoic acid), 119.2 parts of IPDI (isophorone diisocyanate), and 81.4 parts of NPAC (n-propyl acetate) were charged while introducing nitrogen gas. The mixture was reacted at 90°C for 5 hours to obtain a prepolymer solution having isocyanate groups at the ends. Next, a mixture of 18.7 parts AEA (2-(2-aminoethylamino)ethanol), 1.1 parts dibutylamine (hereinafter referred to as "DBA"), and 750.3 parts IPA (isopropyl alcohol) was added dropwise to the resulting urethane prepolymer solution at room temperature over 60 minutes. Then, 14.3 parts of 28% aqueous ammonia and 803.5 parts of deionized water were gradually added to neutralize the carboxyl groups in the resin, thereby making it water-soluble. Next, NPAC and IPA were removed by vacuum distillation to obtain an aqueous solution of polyurethane resin A3 with a solid content of 30%, a mass-average molecular weight of 28,000, Mw / Mn = 3.1, and an acid value of 42.4 mgKOH / g. However, the acid value of A3 is the value before neutralization.

[0103] [Synthesis Example 1-4] (Polyurethane Resin A4) In a reactor equipped with a reflux condenser, dropping funnel, gas inlet tube, stirrer, and thermometer, 135.7 parts of PPA (polyester polyol with a number average molecular weight of 2,000, consisting of a polycondensate of propylene glycol and adipic acid), 13.6 parts of PPG (polyether polyol with a number average molecular weight of 2,000, consisting of polypropylene glycol), 28.3 parts of DMPA (2,2-dimethylolpropanoic acid), 105.7 parts of IPDI (isophorone diisocyanate), and 200 parts of NPAC (n-propyl acetate) were charged while introducing nitrogen gas. The mixture was reacted at 90°C for 5 hours to obtain a urethane prepolymer solution having isocyanate groups at the ends. Next, a mixture of 16.7 parts AEA (2-(2-aminoethylamino)ethanol) and 350 parts IPA (isopropyl alcohol) was added dropwise to the obtained urethane prepolymer solution at room temperature over 60 minutes, and then reacted at 70°C for 3 hours to obtain a polyurethane resin solution. The obtained polyurethane resin solution was mixed with NPAC to adjust the solid content, resulting in a polyurethane resin A4 solution with a solid content concentration of 30%, a mass-average molecular weight of 30,000, Mw / Mn = 3.0, and an acid value of 39.3 mgKOH / g.

[0104] <Manufacturing of desorption layer forming material> [Manufacturing Example 1-1] (Desorption layer forming material P1) 84 parts of polyurethane resin A1 solution, 13 parts of water, and 3 parts of silica particles (P-73, manufactured by Mizusawa Chemical Co., Ltd.: hydrophilic silica particles with an average particle size of 3.8 μm) were mixed and stirred using a disperser to obtain a desorption layer forming material P1.

[0105] [Manufacturing Example 1-2] (Desorption layer forming material P2) 84 parts of polyurethane resin A2 solution, 13 parts of water, and 3 parts of silica particles (P-73, manufactured by Mizusawa Chemical Co., Ltd.: hydrophilic silica particles with an average particle size of 3.8 μm) were mixed and stirred using a disperser to obtain a desorption layer forming material P2.

[0106] [Manufacturing Examples 1-3] (Desorption layer forming material P3) 84 parts of polyurethane resin A3 solution, 13 parts of water, and 3 parts of silica particles (P-73, manufactured by Mizusawa Chemical Co., Ltd.: hydrophilic silica particles with an average particle size of 3.8 μm) were mixed and stirred using a disperser to obtain a desorption layer forming material P3.

[0107] [Production example 1-4] (Detachment layer forming material P4) 84 parts of polyurethane resin A4 solution, 5 parts of ethyl acetate (EA), 5 parts of isopropyl alcohol (IPA), 3 parts of water, and 3 parts of silica particles (P-73, manufactured by Mizusawa Chemical Co., Ltd.: hydrophilic silica particles with an average particle size of 3.8 μm) were mixed and stirred in a disperser to obtain desorption layer forming material P4.

[0108] [Manufacturing Examples 1-5] (Desorption layer forming material P5) Thirty parts of acrylic resin A5 (BASF Joncryl 690) and 67 parts of water were heated to 60°C, and the pH was adjusted to 9.0 using 28% aqueous ammonia. Three parts of silica particles (Mizusawa Chemical Co., Ltd. P-73: hydrophilic silica particles with an average particle size of 3.8 μm) were added to the resulting acrylic resin solution, and the mixture was stirred using a disperser to obtain the desorption layer forming material P5.

[0109] <Functional layer forming material (printing ink)> B1 (Colored Ink): PANNECO AM 39 Indigo, manufactured by Toyo Ink Co., Ltd. B1 (White Ink): PANNECO AM 63 White, manufactured by Toyo Ink Co., Ltd. B2 (Colored Ink): LP Bio SX R39 Blue, manufactured by Toyo Ink Co., Ltd. B2 (White Ink): LP Bio SX R631 White, manufactured by Toyo Ink Co., Ltd. B3 (Colored Ink): Real NEX BOS3 39 Blue, manufactured by Toyo Ink Co., Ltd. B3 (White Ink): Real NEX BOS3 63 White, manufactured by Toyo Ink Co., Ltd.

[0110] <Synthesis of polyols used in adhesives> [Synthesis Example 2-1] (Polyester Polyol E1) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 124 parts ethylene glycol, 212 parts neopentyl glycol, 368 parts 1,6-hexanediol, 645 parts isophthalic acid, 36 parts adipic acid, and 265 parts sebacic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen stream, and the esterification reaction was carried out. After the predetermined amount of water was distilled off and the acid value was reduced to 5 or less, the reaction was continued, and the pressure was gradually reduced to 1 mmHg or less for 5 hours to perform a deglycolization reaction to obtain a polyester polyol. Subsequently, 35 parts isophorone diisocyanate was gradually added, and the reaction was carried out at 150°C for approximately 2 hours to obtain a polyester polyurethane polyol. 12.0 parts of ethylene glycol bisanhydrotrimellitate were added to 100 parts of this polyester polyurethane polyol, and the mixture was reacted at 180°C for approximately 2 hours. The mixture was then diluted with ethyl acetate until the solid content reached 50%, thereby obtaining a solution of partially acid-modified polyester polyol E1 with a number average molecular weight of 9,000 and an acid value of 30.3 mg KOH / g.

[0111] [Synthesis Example 2-2] (Polyester Polyol E2) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 58 parts ethylene glycol, 412 parts diethylene glycol, 343 parts neopentyl glycol, 517 parts isophthalic acid, and 393 parts adipic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen stream, and the esterification reaction was carried out. After the reaction continued until a predetermined amount of water was distilled off and the acid value was 5 or less, the pressure was gradually reduced, and the deglycolization reaction was carried out at 1 mmHg or less for 5 hours to obtain a polyester polyol. 4.0 parts trimellitic anhydride was added to 100 parts of this polyester polyol, and the mixture was reacted at 180°C for about 2 hours. Then, it was diluted with ethyl acetate until the solid content concentration reached 50%, to obtain a solution of partially acid-modified polyester polyol E2 with a number average molecular weight of 2,000 and an acid value of 23.5 mg KOH / g.

[0112] <Preparation of polyisocyanates for use in adhesives> [Preparation Example 1] (Polyisocyanate C1) Coronate 2785 (a biuret-type polyisocyanate derived from hexamethylene diisocyanate, manufactured by Tosoh Corporation) was diluted with ethyl acetate to adjust the solid content to 50% and NCO% to 9.6% to obtain a solution of polyisocyanate C1.

[0113] <Adhesive manufacturing> [Manufacturing Example 3-1] (Adhesive D1) A 30% solids adhesive solution was prepared by mixing 90 parts of polyester polyol E1 solution, 10 parts of polyester polyol E2 solution, and 8 parts of polyisocyanate C1 solution, and then adding ethyl acetate.

[0114] [Manufacturing Example 3-2] (Adhesive D2) A 5% solids adhesive solution was prepared by mixing 90 parts of polyester polyol E1 solution, 10 parts of polyester polyol E2 solution, and 8 parts of polyisocyanate C1 solution, and then adding ethyl acetate.

[0115] <Manufacturing of laminates> The manufacturing method for the laminate is described below. The desorption layer forming materials P4 and P5, and the printing inks B1, B2 and B3 were each diluted using a mixed solvent of EA / IPA (mass ratio 70 / 30), and the desorption layer forming materials P1, P2 and P3 were each diluted using a mixed solvent of water / IPA (mass ratio 20 / 80), so that the viscosity was 15 seconds (25°C, Zahn Cup #3 (manufactured by Rigosha)) before use. The mass of the organic solvent in the desorption layer forming material when printed or coated was calculated from the mass of the organic solvent after diluting the desorption layer forming material with each mixed solvent, based on the mixing ratio.

[0116] [Example 1] (Laminate L1) A desorption layer forming material P1 and the colored and white inks of printing ink B1 were applied in this order at a speed of 70 m / min using a gravure printing press equipped with a gravure plate with a plate depth of 30 μm to an OPP film (single-sided corona-treated stretched polypropylene film, thickness 20 μm). Each unit was dried at 70°C to obtain a laminate L1 consisting of a first plastic substrate (OPP) / desorption layer (P1) / functional layer (B1), with a dried film thickness of 0.1 μm for the desorption layer (P1) and 1.5 μm for the functional layer (B1). The calculated values ​​(1) and (2) of the obtained laminate L1, where the thickness of the desorption layer (P) is A μm, the thickness of the functional layer (F) other than the desorption layer is B μm, and the thickness of the first plastic substrate is C μm, were as follows. (1) A / B = 0.067 (2) (A+B) / C×10=0.8

[0117] [Examples 2-10, 25-42, Comparative Examples 1-4] (Laminates L2-L10, 25-42, Comparative Laminates LL1-LL4) Laminates L2-L10, L25-L42, and comparative laminates LL1-LL4 were obtained using the same method as for laminate L1, except that the base material, desorption layer, functional layer, and adhesive layer were changed as described in Tables 1 and 2. In the production of comparative laminate LL1, no desorption layer was formed, and the printing ink was printed directly onto the OPP film.

[0118] [Example 11] (Laminate L11) A laminate of a plastic substrate (OPP) / deposition layer (P1) / colored layer (B2) was obtained by coating an OPP film (single-sided corona-treated stretched polypropylene film, 20 μm thick) with a deposition layer forming material P1 and the colored and white inks of printing ink B3 in that order at a speed of 70 m / min using a gravure printing press equipped with a gravure plate with a plate depth of 30 μm, and drying each unit at 70°C, resulting in a dried film thickness of 0.1 μm for the deposition layer (P1) and 1.5 μm for the functional layer (B3). Next, adhesive D1 was applied to the printed layer of the obtained laminate using a dry laminating machine to a thickness of 2.5 μm after drying, and then laminated with a CPP film (unoriented polypropylene film) to obtain a laminate L29 consisting of a plastic substrate (OPP) / desorption layer (P1) / coloring layer (B3) / adhesive layer (C1) / plastic substrate (CPP).

[0119] [Examples 12-18, 21, Comparative Examples 5-9] (Laminates L12-18, 21, Comparative Laminates LL5-LL9) Laminates L12-18, 21, and comparative laminates LL5-LL9 were obtained using the same method as for the production of laminate L11, except that the base material, desorption layer, functional layer, and adhesive layer were changed as described in Tables 1 and 2. In the production of comparative laminate LL5, no desorption layer was formed, and the printing ink was printed directly onto the OPP film.

[0120] [Example 19] (Laminate L19) A desorption layer forming material P1 and the colored and white inks of printing ink B1 were applied in this order at a speed of 70 m / min using a gravure printing press equipped with a gravure plate with a plate depth of 30 μm, to an OPP film (single-sided corona-treated stretched polypropylene film, 20 μm thick). Each unit was dried at 70°C to obtain a laminate of a plastic substrate (OPP) / desorption layer (P1) / functional layer (B2) with a dried film thickness of 0.5 μm for the desorption layer (P1) and 1.5 μm for the functional layer (B1). Next, adhesive D2 was applied to the printed layer of the resulting laminate using a dry laminating machine and dried to a film thickness of 1.0 μm after drying. Then, it was laminated with a VMPET film (metallized polyester, 12 μm thick) to obtain a laminate consisting of a first plastic substrate (OPP) / desorption layer (P1) / functional layer (B1) / adhesive layer (D2) / intermediate substrate (VMPET). Next, adhesive D2 was applied to the PET surface of VMPET using a dry laminating machine and dried to a film thickness of 1.0 μm after drying. Then, it was laminated with a CPP film (unoriented polypropylene film, 20 μm thick) to obtain a laminate L19 consisting of a first plastic substrate (OPP) / desorption layer (P1) / functional layer (B1) / adhesive layer (D2) / intermediate substrate (VMPET) / adhesive layer (D1) / second plastic substrate (CPP).

[0121] [Example 20] (Laminate L20) Laminate L20 was obtained in the same manner as in the manufacture of laminate L17, except that the base material, desorption layer, functional layer, and adhesive layer were changed to those described in Tables 1 and 2.

[0122] [Example 22] (Laminate L22) A PET film (one-sided corona-treated polyester film, 12 μm thick) was coated in this order with a desorption layer forming material P1 and the colored and white inks of printing ink B1 using a gravure printing press equipped with a gravure plate with a plate depth of 30 μm at a speed of 70 m / min. Each unit was dried at 70°C to obtain a laminate of a plastic substrate (PET) / desorption layer (P1) / functional layer (B1) with a dried film thickness of 0.5 μm for the desorption layer (P1) and 1.5 μm for the functional layer (B1). Next, adhesive D1 was applied to the printed layer of the resulting laminate using a dry laminating machine and dried to a film thickness of 2.5 μm after drying. Then, it was bonded with an NY film (single-sided corona-treated nylon film, 15 μm thick) to obtain a laminate consisting of a first plastic substrate (PET), a desorption layer (P1), a functional layer (B1), an adhesive layer (D1), and an intermediate substrate (NY). Next, adhesive D1 was applied to the side opposite the functional layer of NY using a dry laminating machine and dried to a film thickness of 1.0 μm after drying. Then, it was laminated with a CPP film (unoriented polypropylene film, 20 μm thick) to obtain a laminate L22 consisting of a first plastic substrate (OPP) / desorption layer (P1) / functional layer (B1) / adhesive layer (D1) / intermediate substrate (VMPET) / adhesive layer (D1) / second plastic substrate (CPP).

[0123] [Example 23] (Laminate L23) A laminate consisting of a first plastic substrate (OPP) / deposition layer (P1) / functional layer (B2) was obtained by coating an OPP film (one-sided corona-treated stretched polypropylene film, 20 μm thick) with a deposition layer forming material P1 and the colored and white inks of printing ink B2 in that order at a speed of 70 m / min using a gravure printing press equipped with a gravure plate with a plate depth of 30 μm, and drying each unit at 70°C, resulting in a dried film thickness of 0.2 μm for the deposition layer (P1) and 1.5 μm for the functional layer (B2). Next, adhesive D2 is applied to the printed layer of the resulting laminate using an extrusion laminating machine so that the film thickness after drying is 1.0 μm, and then dried onto high-quality paper (basis weight 50 g / m²). 2 By bonding it with the first plastic substrate (OPP), a laminate was obtained consisting of a first plastic substrate (OPP), a desorption layer (P1), a functional layer (B2), an adhesive layer (D2), and paper (carton paper). Next, adhesive D2 was applied to the opposite side of the high-quality paper laminated with the plastic substrate using a dry laminating machine, and dried to a film thickness of 1.0 μm after drying. Then, it was laminated with a PE film (polyethylene film, 20 μm thick) to obtain a laminate L23 consisting of a first plastic substrate (OPP) / desorption layer (P1) / functional layer (B2) / adhesive layer (D2) / paper (high-quality paper) / adhesive layer (D2) / second plastic substrate (PE).

[0124] [Example 24, Comparative Example 10] (Laminate L24, Comparative Laminate LL10) Laminate L24 and comparative laminate LL10 were obtained using the same method as in the manufacture of laminate L23, except that the base material, desorption layer, functional layer, and adhesive layer were changed to those described in Tables 1 and 2. In the manufacture of comparative laminate LL10, no desorption layer was formed, and the printing ink was printed directly onto the LLDPE film.

[0125] <Rating> The laminates L1-42 and LL1-10 of Examples 1-42 and Comparative Examples 1-10 were evaluated as follows. The results are shown in Table 3.

[0126] <Blocking resistance> In the manufacturing processes for L1-42 and LL1-10, the laminate with the functional layer (or, in the case of a laminated structure, the laminate with the functional layer before lamination) is cut to a size of 4cm x 4cm, and the printed and unprinted sides are combined at 10kg / cm². 2 After applying a load and leaving it in a 60°C atmosphere for 24 hours, the printed surface was peeled off, and the blocking resistance was evaluated based on the degree of ink peeling. A, B, and C are within a range that does not pose a practical problem. [Evaluation Criteria] A (Excellent): Products where less than 10% of the functional layer (colored layer) has peeled off from the film. B (Good): The area where the functional layer (colored layer) has peeled off from the film is 10% or more but less than 25%. C (Acceptable): The area where the functional layer (colored layer) has been peeled off from the film is 25% or more but less than 50%. D (Not acceptable): Products where 50% or more of the functional layer (colored layer) has been peeled off from the film.

[0127] <Residual solvent> Each laminate (L1-42, LL1-10) was cut into five 10cm squares. The five cut samples were heated at 180°C for 20 minutes, and the change in mass before and after heating was calculated for each sample. The average value of the change in mass relative to the mass before heating for the five samples was defined as the residual solvent amount. A, B, and C are within a range that does not pose a practical problem. [Evaluation Criteria] A (Excellent): Products with a residual solvent content of less than 1.0 mg. B (Good): Residual solvent content is 1.0 mg or more but less than 3.0 mg. C (Acceptable): Residual solvent content is 3.0 mg or more but less than 5.0 mg. D (Not acceptable): Products with a residual solvent content of 5.0 mg or more.

[0128] <Lamination Strength> Each laminate (L11-24, LL1-10) was cut into 15mm widths, and its delamination strength was evaluated using an Intesco tensile testing machine. A, B, and C are within a range that does not pose practical problems. Examples 1-10 and 25-42 do not involve laminating multiple film substrates, therefore the lamination strength is not measured. [Evaluation Criteria] A (excellent): 1.0Kgf or more B (Good): 0.7 kgf or more and less than 1.0 kgf C (acceptable): 0.5 kgf or more and less than 0.7 kgf D (Not acceptable): Less than 0.5 kgf

[0129] <Detaching> Each laminate (L1-42, LL1-10) was cut into 1cm x 1cm pieces and immersed in a 2% by mass sodium hydroxide aqueous solution at 70°C to evaluate the degree of desorption of the desorption layer. [Evaluation Criteria] A (Excellent): Detached in less than 1 hour B (Good): Detachment occurred between 1 and 3 hours. C (acceptable): Detachment occurs between 3 and 24 hours. D (Not possible): Still not detached after more than 24 hours.

[0130] <Coloring of recycled film> 50g of each laminate (L1-42, LL1-10) was cut into 1cm x 1cm pieces and placed in 2000g of a 2% by mass sodium hydroxide aqueous solution, which was then stirred at 70°C for 3 hours. After cooling, the mixture was filtered through a 5mm mesh sieve and washed with deionized water. For Examples 1-36, 38 and Comparative Examples 1-9, only the plastic substrate was recovered, while for Examples 37, 39-42 and Comparative Example 10, only the floating polyolefin substrate was recovered by specific gravity separation. The obtained plastic substrates were dried at 70°C for one week. The recovered recycled plastic substrates were pelletized at a melting temperature of 230°C for polyolefin or NY substrates, and 290°C for PET substrates, to obtain pellets (molding material). These pellets were extruded using a T-die film molding machine at 230°C for polyolefin substrates and 290°C for PET substrates to produce recycled films (molded bodies) with a thickness of 100μm. The coloration of the recycled film was measured using a haze meter (SH7000, manufactured by JEOL Ltd.) and evaluated according to the following criteria. [Evaluation Criteria] A (Excellent): Total light transmittance is 90% or higher. B (Good): Total light transmittance is 80% or more but less than 90% C (acceptable): Total light transmittance is 70% or more but less than 80% D (Not acceptable): Total light transmittance is less than 70%

[0131] [Table 1]

[0132] Table 1 shows the types and thicknesses of substrates used in Tables 2-1 and 2-2. The abbreviations used in the table are as follows: PET: Polyethylene terephthalate NY: Nylon VMPET: Aluminum vapor-deposited polyethylene terephthalate VMOPP: Aluminum-coated biaxially oriented polypropylene VMCPP: Aluminum-coated unoriented polypropylene

[0133] [Table 2-1]

[0134] [Table 2-2]

[0135] In the table, *Organic solvent amount refers to "Amount of volatile organic solvent in the desorption layer forming material."

[0136] Based on the evaluation results above, the embodiments of the present invention demonstrate that, in a laminate having a plastic substrate, a desorption layer, and a functional layer other than the desorption layer in this order, it is possible to provide a laminate that achieves both blocking resistance and lamination strength of the laminate and desorption properties of the desorption layer, and can suppress discoloration of the molding material and molded article obtained by recycling the plastic substrate, as well as a method for manufacturing a recycled plastic substrate, molding material, and molded article.

Claims

1. A laminate having a first plastic substrate, a desorption layer (P), and a functional layer other than the desorption layer (F) adjacent to each other in this order, The desorption layer (P) has the property of being detached from the first plastic substrate by contact with a desorption solution containing a basic compound. The desorption layer (P) contains a water-soluble urethane resin, A laminate in which the thickness of the desorption layer (P) is 0.1 μm or more and 1.0 μm or less.

2. The laminate according to claim 1, wherein the acid value of the water-soluble urethane resin is 10 mg KOH / g or more and 45 mg KOH / g or less.

3. The laminate according to claim 1, wherein the weight-average molecular weight of the water-soluble urethane resin is 10,000 or more and 50,000 or less.

4. A laminate having a first plastic substrate, a desorption layer (P), and a functional layer other than the desorption layer (F) adjacent to each other in this order, The desorption layer (P) has the property of being detached from the first plastic substrate by contact with a desorption solution containing a basic compound. The desorption layer (P) contains a water-soluble urethane resin, A laminate that satisfies both of the following conditions (1) and (2), where the thickness of the desorption layer (P) is A μm, the thickness of the functional layer (F) other than the desorption layer is B μm, and the total thickness of all plastic substrates included in the laminate is C μm. (1) A / B is 0.1 or more and 0.6 or less (2) (A + B) / C × 10 is between 0.4 and 1.5

5. A laminate according to claim 1 or 4, Furthermore, it has an adhesive layer, A laminate that satisfies either condition (3) or (4) below, where the thickness of the desorption layer (P) is A μm, the thickness of the functional layers other than the desorption layer (F) (excluding the adhesive layer) is B μm, the total thickness of all plastic substrates included in the laminate is C μm, and the thickness of the adhesive layer is D μm. (3) (A + D) / C × 10 is between 0.25 and 1.0 (4) (A + B + D) / C × 10 is between 0.5 and 1.5

6. The laminate according to claim 1 or 4, wherein the content of polyolefin resin contained in the plastic substrate in the laminate is 60% by mass or more, based on the total mass of the plastic substrate in the laminate.

7. Furthermore, the laminate according to claim 1 or 4, further comprising a paper substrate.

8. A method for manufacturing a laminate according to claim 1 or 4, wherein a desorption layer forming material for forming a desorption layer (P) is laminated onto a first plastic substrate by printing or coating, and the mass of the organic solvent in the desorption layer forming material at the time of printing or coating is 20% by mass or more and 90% by mass or less.

9. The method for producing a laminate according to claim 8, wherein the organic solvent contains a water-soluble organic solvent with a boiling point of 150°C or lower.

10. A method for producing a recycled plastic substrate, comprising a desorption step of contacting the laminate according to claim 1 or 4 with a desorption solution containing a basic compound at 30°C or higher, thereby desorbing a desorption layer (P) from the first plastic substrate.

11. A method for producing a recycled plastic substrate according to claim 10, comprising a cutting step of cutting the laminate according to claim 1 or 4 so that the maximum diameter is 1 to 50 mm, prior to the desorption step.

12. A method for producing a molding material, comprising the step of producing a pellet-shaped molding material by melting and kneading a recycled plastic substrate produced by the method for producing a recycled plastic substrate described in claim 10 at 140 to 290°C, and then cutting it.

13. A method for manufacturing a molded article, comprising the step of heat-molding a molding material manufactured by the manufacturing method described in claim 12.

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