Layered body, method for producing same, and molded article

Abstract

This layered body comprises, in order, a substrate layer (A), an adhesive resin layer (B), and a resin layer (D) containing a copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate. The basis weight of the adhesive resin layer (B) is 0.1 g / m2 or greater but less than 3.0 g / m2; the average content ratio of 3-hydroxyhexanoate in the copolymer (C) is 6 mol% or greater; and the thickness of the resin layer (D) is 20 μm or greater but less than 100 μm.

Description

Laminate, manufacturing method thereof, and molded product

[0001] The present invention relates to a laminate in which a resin layer is laminated on at least one surface of a base layer such as paper, a method for producing the same, and a molded product thereof.

[0002] In recent years, environmental problems caused by discarded plastics have been attracting attention. In particular, marine pollution caused by discarded plastics is serious, and there are high hopes for the widespread use of biodegradable plastics that decompose in the natural environment.

[0003] A variety of such biodegradable plastics are known, including a copolymer of 3-hydroxybutyrate (hereinafter sometimes referred to as "3HB") and 3-hydroxyhexanoate (hereinafter sometimes referred to as "3HH") (hereinafter sometimes referred to as "PHBH"), a thermoplastic polyester that is produced and accumulated as an energy storage substance within the cells of many microbial species. Because it is a material that can biodegrade not only in soil but also in seawater, it has attracted attention as a material that can solve the above-mentioned problems. Among these, PHBH / paper composites, in which PHBH is integrated with a substrate such as paper, have attracted particular public interest because they can be used in food-contact containers and other applications that have a low environmental impact.

[0004] Methods for integrating PHBH and paper include extrusion lamination and aqueous slurry coating. However, extrusion lamination is preferred because coating methods tend to fail to provide sufficient mechanical strength for the resin layer. However, because PHBH generally has a high melt viscosity and poor adhesion to paper, it has not been easy to bond extruded PHBH and paper with sufficient strength. As a result, during the manufacturing process of cup-shaped products such as beverage cups, the laminate layer can peel off from the paper, causing problems such as leakage of contents when filled.

[0005] Patent Document 1 does not disclose PHBH, but it describes a method of applying a polycaprolactone dispersion or emulsion to paper at a rate of 10 g / m² in order to improve the penetration of biodegradable resin into paper and thereby improve laminate strength. ２This method involves applying a coating of the film at a basis weight (dry weight of the layer) of 1000 ppm, drying it, and then laminating 3-hydroxybutyric acid / 3-hydroxyvaleric acid copolymer (PHBV) by extrusion lamination.

[0006] Japanese Patent Application Publication No. 6-293113

[0007] According to the method of Patent Document 1, the adhesion between the paper and the resin layer tends to be improved, but the polycaprolactone dispersion or emulsion is used at a concentration of 10 g / m ２ Since the paper is applied at such a large basis weight and then dried, the drying process takes a long time, resulting in low productivity. In addition, there are problems such as deterioration of the paper substrate due to the drying process, or the paper drying out too much, causing warping of the laminate.

[0008] To facilitate drying, the adhesive layer has a weight of 10 g / m ２ Although there are methods for reducing the amount of resin, in such cases there is a problem that the adhesion between the paper substrate and the resin layer becomes insufficient.

[0009] In view of the above-described current situation, an object of the present invention is to provide a laminate comprising, in this order, a base layer, an adhesive layer, and a resin layer containing a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate, which has good drying properties when the adhesive layer is formed, and has high adhesive strength between the base layer and the resin layer.

[0010] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that in a laminate comprising, in this order, a base material layer (A), an adhesive resin layer (B), and a resin layer (D) containing a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate, the above-mentioned problems can be solved by setting the thickness of the resin layer (D) within a specific range while making the basis weight of the adhesive resin layer (B) sufficiently small, and have thus completed the present invention.

[0011] That is, the present invention provides a laminate comprising, in this order, a substrate layer (A), an adhesive resin layer (B), and a resin layer (D) containing a copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate, wherein the adhesive resin layer (B) has a basis weight of 0.1 g / m ２ Above, 3.0g / m ２The present invention also relates to a method for producing the laminate, comprising: a first step of forming the adhesive resin layer (B) on at least one surface of the base layer by a coating method; and a second step of forming the resin layer (D) on the surface of the adhesive resin layer (B) by an extrusion lamination method or a thermal lamination method.

[0012] According to the present invention, there is provided a laminate comprising, in this order, a base layer, an adhesive layer, and a resin layer containing a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate, which exhibits good drying properties when the adhesive layer is formed and has high adhesive strength between the base layer and the resin layer. Use of this laminate can improve the production efficiency and quality of molded articles.

[0013] 1 is a schematic diagram illustrating a stack structure of a stack according to an embodiment of the present invention.

[0014] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0015] [Laminate] A laminate according to one embodiment of the present invention has an adhesive resin layer (B) and a resin layer (D) containing a copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate on at least one surface of a base layer (A). As shown in Figure 1, in the laminate 1, the base layer (A) indicated by reference numeral 2, the adhesive resin layer (B) indicated by reference numeral 3, and the resin layer (D) indicated by reference numeral 4 are laminated in this order.

[0016] The adhesive resin layer (B) may be laminated directly on the base material layer (A), or another resin layer may be further included as an intermediate layer between the adhesive resin layer (B) and the base material layer (A) as long as the adhesiveness is not impaired.

[0017] The adhesive resin layer (B) and the resin layer (D) may be provided on only one side of the base layer (A), or the adhesive resin layer (B) and the resin layer (D) may be provided on each of both sides of the base layer (A).

[0018] When the adhesive resin layer (B) and the resin layer (D) are formed on only one side of the base material layer (A), no other layer is formed on the other side, and the base material layer (A) may be the outermost layer exposed on the surface of the laminate, or another layer may be laminated thereon for the purpose of imparting water resistance, gloss, or adhesiveness, etc.

[0019] When the adhesive resin layer (B) and the resin layer (D) are provided on both sides of the substrate layer (A), the materials constituting the adhesive resin layer (B) on the front side and the adhesive resin layer (B) on the back side, the basis weight and thickness may be the same or different. The same applies to the resin layer (D) on the front side and the resin layer (D) on the back side. In this application, the basis weight (g / m ２ ) refers to the dry weight (solids content) of the layer.

[0020] [Substrate layer (A)] The material constituting the substrate layer (A) is not particularly limited, but is preferably biodegradable, and examples thereof include paper (mainly composed of cellulose), cellophane, cellulose ester, polyvinyl alcohol, polyamino acid, polyglycolic acid, pullulan, or a substrate having an inorganic material such as aluminum or silica vapor-deposited thereon. Among these, paper is preferred because of its excellent heat resistance and low cost.

[0021] The type of paper is not particularly limited and can be appropriately selected depending on the application of the laminate, and examples include cup base paper, kraft paper, fine paper, coated paper, tissue paper, glassine paper, paperboard, etc. If necessary, a water-resistant agent, a water-repellent agent, an inorganic substance, etc. may be added to the paper, and the paper may be subjected to a surface treatment such as an oxygen barrier layer coating or a water vapor barrier coating.

[0022] The substrate layer (A) may also be subjected to a surface treatment such as corona treatment, ozone treatment, plasma treatment, frame treatment, anchor coat treatment, oxygen barrier layer coating, water vapor barrier coating, etc. These surface treatments may be performed alone or in combination.

[0023] [Adhesive Resin Layer (B)] The adhesive resin layer (B) is a layer composed primarily of a resin. The main resin contained in the adhesive resin layer (B) is not particularly limited, but resins commonly used in the fields of coated paper and resin films can be suitably used. It is desirable for the adhesive resin layer (B) to contain at least one resin that has a high affinity with substrates such as paper and PHBH. Examples of such resins include acrylic resins, methacrylic resins, vinyl chloride resins, styrene-acrylic resins, styrene-butadiene resins, styrene-isoprene resins, polycarbonate resins, urea resins, melamine resins, epoxy resins, phenolic resins, urethane resins, diallyl phthalate resins, and imine resins. These resins can be used alone, or two or more resins can be mixed in any ratio.

[0024] The resin contained in the adhesive resin layer (B) may be water-soluble or soluble in an organic solvent. When using a water-insoluble resin, other additives can be added to improve dispersibility in water and coatability. When coating an aqueous emulsion, aqueous slurry, or water-soluble resin, the solids concentration of the resin is not particularly limited, but is preferably 30% by weight or more, more preferably 40% by weight or more, and even more preferably 50% by weight or more in order to reduce the amount of heat required for drying. Furthermore, from the viewpoint of avoiding sedimentation of the dispersed resin and achieving good coatability, the solids concentration is preferably 60% by weight or less.

[0025] In the laminate according to this embodiment, the weight per unit area of ​​the adhesive resin layer (B) is 0.1 g / m ２ Above, 3.0g / m ２ The weight is adjusted to a range of less than 0.1 g / m ２ If the amount is less than 3.0 g / m, the adhesiveness to the resin layer (D) may decrease. ２ If the weight is more than 0.5 g / m, a large amount of heat is required during drying, which increases the load on the equipment, and for example, insufficient drying may cause blocking when the raw material is wound up. ２ Above, 2.5g / m ２More preferably, it is 1.0 g / m or less. ２ Above, 2.0g / m ２ It is even more preferable that:

[0026] [Resin Layer (D)] The resin layer (D) contains a copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate (hereinafter, may be referred to as "PHBH"). The resin layer (D) may be the outermost layer in the laminate according to this embodiment, and in that case, the resin layer (D) can be used for heat sealing (described below).

[0027] By changing the content ratio of the repeating units, the melting point and crystallinity of PHBH can be changed, and as a result, physical properties such as Young's modulus and heat resistance can be easily adjusted, and it is possible to impart physical properties between those of polypropylene and polyethylene, making it an especially useful plastic industrially.

[0028] A specific method for producing PHBH is described in, for example, International Publication No. 2010 / 013483. Commercially available PHBH products include Kaneka Biodegradable Polymer Green Planet (registered trademark) manufactured by Kaneka Corporation.

[0029] The average content ratio of the constituent monomers in PHBH (C) is preferably 3HB / 3HH = 94 to 80 / 6 to 20 (mol % / mol %), and more preferably 3HB / 3HH = 90 to 82 / 10 to 18 (mol % / mol %). When the average content ratio of 3HH in PHBH (C) is 6 mol % or more, good adhesion to the adhesive resin layer (B) formed on a substrate such as paper can be achieved. Furthermore, when the average content ratio of 3HH is 20 mol % or less, the crystallization rate of PHBH is not too slow, and production is relatively easy.

[0030] The average content ratio of each constituent monomer in PHBH(C) means the molar ratio of 3HB and 3HH contained in PHBH(C). When PHBH(C) is a mixture of at least two types of PHBH having different content ratios of the constituent monomers, or when PHBH(C) is a mixture containing at least one type of PHBH and PHB, the average content ratio means the molar ratio of each constituent monomer contained in the entire mixture. The average content ratio of the constituent monomers can be determined by methods known to those skilled in the art, for example, the method described in paragraph

[0047] of WO 2013 / 147139, or by NMR measurement.

[0031] As described above, the PHBH (C) contained in the resin layer (D) may contain at least two types of PHBH having different content ratios of constituent monomers, or may further contain PHB (a homopolymer of 3-hydroxybutyrate) in addition to at least one type of PHBH.

[0032] When at least two types of PHBH are contained, it is preferable that the PHBH contain a highly crystalline, high-melting-point PHBH having a 3HH content of less than 6 mol % and a low-crystalline, low-melting-point PHBH having a 3HH content of 15 mol % or more.

[0033] In particular, the PHBH (C) contained in the resin layer (D) preferably contains at least two types of PHBH components: a first melting point component (low crystalline component) having a melting point of 60° C. or higher and lower than 90° C., and a second melting point component (high crystalline component) having a melting point of 140° C. or higher and lower than 170° C. In particular, the melting point of the first melting point component is preferably 65° C. or higher and 85° C. or lower, more preferably 70° C. or higher and 80° C. or lower, and the melting point of the second melting point component is preferably 145° C. or higher and 165° C. or lower, more preferably 150° C. or higher and 160° C. or lower. With this configuration, compared to when the resin layer (D) contains only PHBH alone, the crystals of the second melting point component are not completely dissolved during melt processing, but remain and act as crystal nuclei, thereby accelerating the crystallization of PHBH (C). This not only facilitates the formation of the resin layer (D) by extrusion lamination or thermal lamination, but also increases the adhesive strength with the adhesive resin layer (B) formed on a substrate such as paper, due to the first melting point component being sufficiently melted.

[0034] PHB can be used instead of highly crystalline PHBH having a 3HH content of less than 6 mol %, and in this case, the PHB acts as a crystal nucleus, so the same effect can be obtained. Note that PHBH having a 3HH content of less than 6 mol % and PHB may be used in combination.

[0035] The ratio of 3HH to the total of 3HB and 3HH in the highly crystalline PHBH is preferably 5 mol % or less, more preferably 4 mol % or less, and even more preferably 3 mol % or less.The ratio of 3HH to the total of 3HB and 3HH in the low crystalline PHBH is preferably 15 to 40 mol %, more preferably 15 to 30 mol % or less.

[0036] The amount of the highly crystalline PHBH or PHB blended is not particularly limited, but is preferably 1 to 60% by weight, more preferably 2 to 50% by weight, and even more preferably 4 to 15% by weight of the PHBH (C) contained in the resin layer (D).

[0037] The weight-average molecular weight (hereinafter sometimes referred to as Mw) of the PHBH (C) contained in the resin layer (D) is preferably 250,000 to 650,000, more preferably 350,000 to 550,000, and even more preferably 400,000 to 500,000, from the viewpoint of achieving both mechanical properties and processability. When the weight-average molecular weight is 250,000 or more, the mechanical properties of the resin layer (D) are good, and when it is 650,000 or less, the resin layer (D) can exhibit a melt viscosity suitable for molding and can have better adhesion to the adhesive resin layer (B) formed on a substrate such as paper.

[0038] In the present application, the weight-average molecular weight of PHBH can be determined as a polystyrene-equivalent molecular weight by gel permeation chromatography (GPC) (Shodex GPC-101 manufactured by Showa Denko K.K.) using a polystyrene gel (Shodex K-804 manufactured by Showa Denko K.K.) as a column and chloroform as a mobile phase.

[0039] In one embodiment of the present invention, a mixture of multiple types of PHBH having different weight average molecular weights can be used in the resin layer (D).

[0040] The resin layer (D) is preferably a resin layer containing PHBH(C) as a main component. Specifically, the content of PHBH(C) in the resin layer (D) is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, and even more preferably 80 to 100% by weight. The lower limit may be 90% by weight or more, or 95% by weight or more.

[0041] The resin layer (D) may contain only PHBH or only PHBH and PHB as the resin component, or may further contain a resin other than PHBH and PHB in addition to these. The resin other than PHBH and PHB is preferably a biodegradable resin, and specific examples thereof include poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB3HV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PHB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (PHB3HO), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate) (PHB3HOD), poly(3-hydroxybutyrate-co- Examples of suitable resins include poly(3-hydroxyalkanoates) such as poly(3-hydroxydecanoate) (PHB3HD) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHB3HV3HH); aliphatic polyester resins such as polycaprolactone, polybutylene succinate adipate, polybutylene succinate, and polylactic acid; and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate and polybutylene azelate terephthalate. These resins other than PHBH and PHB may be used alone or in combination of two or more.

[0042] The resin layer (D) may contain additives typically added to resin materials, provided that the effects of the present invention are not impaired. Examples of such additives include inorganic fillers, colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolite, fragrances such as vanillin and dextrin, plasticizers, antioxidants, weather resistance improvers, UV absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and sliding properties improvers. These additives may be used alone or in combination of two or more. However, additives are optional components, and the resin layer (D) may not contain these additives. It is preferable to use a lubricant and / or an inorganic filler as additives, as this improves the releasability of the resin layer (D) from the pressure-bonding surface of a cooling roll or the like during lamination.

[0043] Examples of the lubricant include saturated or unsaturated fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, and erucic acid amide; aliphatic amide compounds such as alkylene fatty acid amides such as methylene bisstearic acid amide and methylene bisstearic acid amide; and pentaerythritol.

[0044] The amount of lubricant in the resin layer (D) is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1 part by weight, per 100 parts by weight of the total amount of resin components contained in the resin layer (D). By setting the amount to 0.1 part by weight or more, the effect of improving releasability due to the addition of the lubricant can be obtained. If the amount is 2 parts by weight or less, the problem of the lubricant bleeding and adhering to the pressure-bonding surface of a cooling roll or the like during compression bonding can be suppressed, and long-term continuous processing can be performed.

[0045] Examples of the inorganic filler include talc, calcium carbonate, mica, silica, clay, kaolin, titanium oxide, alumina, zeolite, etc. The average particle size of these inorganic fillers is preferably 0.5 μm or more.

[0046] The amount of inorganic filler in the resin layer (D) is preferably 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight, per 100 parts by weight of the total amount of resin components contained in the resin layer (D). By setting the amount to 0.5 parts by weight or more, the effect of improving releasability due to the incorporation of the inorganic filler can be obtained. When the amount is 5 parts by weight or less, the occurrence of cracks in the resin layer (D) can be suppressed.

[0047] In the laminate according to this embodiment, the thickness of the resin layer (D) is set to a range of 20 μm or more and less than 100 μm. If the thickness is less than 20 μm, the resin may cool too quickly during lamination of the resin layer (D), resulting in a decrease in adhesion to the substrate layer (A) on which the adhesive resin layer (B) is formed. In addition, cracks are likely to occur in the resin layer (D) when the laminate is processed into a molded product. The lower limit of the thickness is preferably 20 μm or more, more preferably 30 μm or more, and particularly preferably 40 μm or more.

[0048] Furthermore, if the thickness of the resin layer (D) exceeds 100 μm, the resin temperature may become uneven during the formation of the resin layer (D), which may cause uneven thickness or poor appearance due to melt fracture. Furthermore, the laminate may become too hard, resulting in molding defects. The upper limit of the thickness is preferably 80 μm or less, more preferably 60 μm or less.

[0049] [Method for producing laminate] An example of a method for producing the laminate according to this embodiment will be described below. The laminate according to this embodiment can be produced by forming an adhesive resin layer (B) on at least one surface of a base layer (A) by a coating method (first step), and then forming a resin layer (D) on the surface of the formed adhesive resin layer (B) (second step).

[0050] In the first step of forming the adhesive resin layer (B) on at least one surface of the base layer (A), it is preferable to apply a solution or an aqueous dispersion such as an aqueous slurry containing the components constituting the adhesive resin layer (B) to one or both surfaces of the base layer (A), and then heat and dry the applied solution to form a film.

[0051] The method for applying the solution or aqueous dispersion to the substrate is not particularly limited, and any known method capable of forming a resin layer on the substrate can be used as appropriate. Specifically, a spraying method, a scattering method, a slit coater method, an air knife coater method, a roll coater method, a bar coater method, a comma coater method, a blade coater method, a screen printing method, a gravure printing method, or the like can be used. Before applying the solution or aqueous dispersion, a step of subjecting the substrate to a surface treatment such as the above-mentioned corona treatment may be carried out.

[0052] The drying treatment after coating can be carried out using a known heating method, such as hot air heating, infrared heating, microwave heating, roll heating, or hot plate heating, which can be used alone or in combination of two or more.

[0053] Next, a second step is performed in which a resin layer (D) is formed on the surface of the formed adhesive resin layer (B). The method for forming the resin layer (D) may be a method in which a solution or aqueous dispersion containing the components constituting the resin layer (D) is applied to the surface of the adhesive resin layer (B), and then heated to dry and form a film. However, from the viewpoint of adhesion to the adhesive resin layer (B), productivity, or quality in suppressing thermal degradation, it is preferable to form the resin layer (D) on the surface of the adhesive resin layer (B) by extrusion lamination or thermal lamination.

[0054] As the extrusion lamination method, a general extrusion lamination method can be used. Specifically, a molten resin material is extruded into a film shape from a T-shaped die, and is pressed onto the surface of the adhesive resin layer (B) while being cooled using a cooling roll, and immediately thereafter, the resin material is peeled off from the cooling roll to form the resin layer (D), thereby producing a laminate.

[0055] As the thermal lamination method, a general thermal lamination method can be used. Specifically, first, a molten resin material is extruded, for example, through a T-shaped die, and cooled using a cooling roll to form a film containing the resin material. Next, the obtained film is pressure-bonded to the surface of the adhesive resin layer (B) using a heated roll or the like, thereby producing a molded product.

[0056] For the purpose of improving the adhesion between the resin layer (D) and the base layer (A) on which the adhesive resin layer (B) is formed, the surface of the adhesive resin layer (B) may be subjected to corona treatment, flame treatment, ozone treatment, or the like.

[0057] From the viewpoint of adhesiveness and processability (balance between melting and crystallization), it is preferable that the first and second steps are carried out successively.

[0058] [Molded Article] A molded article according to one aspect of the present embodiment includes the laminate described above and has a desired size and shape. The molded article is formed from a laminate including a resin layer (D) containing PHBH, and is therefore advantageous in various applications.

[0059] The molded article is not particularly limited as long as it contains the laminate, and examples thereof include paper, film, sheet, tube, plate, rod, container (e.g., bottle container), bag, part, etc. From the viewpoint of measures against marine pollution, the molded article is preferably a bag or a bottle container.

[0060] The molded article may be the laminate itself, or may be a product of secondary processing of the laminate.

[0061] By subjecting the laminate to secondary processing, the molded article can be suitably used as various packaging container materials such as shopping bags, various bags, food and confectionery packaging materials, cups, trays, cartons, etc. (in other words, in various fields such as food, cosmetics, electronics, medicine, and pharmaceuticals.) The laminate includes a resin layer (D) having high adhesion to the substrate and good heat resistance, and is therefore more suitable as a container for holding liquids, particularly as a container for holding hot contents, such as cups for food and drink such as instant noodles, instant soup, and coffee, trays for prepared meals, boxed lunches, and microwaveable foods.

[0062] The secondary processing can be carried out in the same manner as conventional resin-laminated paper or coated paper, i.e., using various bag-making machines, filling and packaging machines, etc. Processing can also be carried out using machines such as paper cup forming machines, punching machines, box making machines, etc. In these processing machines, known techniques can be used to bond the laminate, such as heat sealing, impulse sealing, ultrasonic sealing, high-frequency sealing, hot air sealing, and frame sealing.

[0063] The heat-sealing temperature of the laminate varies depending on the adhesion method. For example, when a heating-type heat-sealing tester with a seal bar is used, the resin temperature is usually set to 180°C or less, preferably 170°C or less, and more preferably 160°C or less. Within the above range, melting of the resin near the sealed portion can be avoided, and an appropriate resin layer thickness and seal strength can be ensured. Furthermore, when a heating-type heat-sealing tester with a seal bar is used, the lower limit of the resin temperature is usually 100°C or more, preferably 110°C or more, and more preferably 120°C or more. Within the above range, appropriate adhesion at the sealed portion can be ensured.

[0064] The heat-sealing pressure of the laminate varies depending on the bonding method, but for example, when a heat-sealing tester with a seal bar is used, it is usually 0.1 MPa or more, preferably 0.5 MPa or more. Within this range, appropriate adhesion at the sealed portion can be ensured. Furthermore, when a heat-sealing tester with a seal bar is used, the upper limit of the heat-sealing pressure is usually 1.0 MPa or less, preferably 0.75 MPa or less. Within this range, thinning of the film thickness at the sealed end can be avoided, and seal strength can be ensured.

[0065] In order to improve the physical properties of the molded article, the molded article can be composited with another molded article made of a material different from the molded article (for example, fiber, thread, rope, woven fabric, knitted fabric, nonwoven fabric, paper, film, sheet, tube, plate, rod, container, bag, part, foam, etc.). These materials are also preferably biodegradable.

[0066] The following items are preferred embodiments of the present disclosure, but the present invention is not limited to the following items. [Item 1] A laminate comprising, in this order, a substrate layer (A), an adhesive resin layer (B), and a resin layer (D) containing a copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate, wherein the adhesive resin layer (B) has a basis weight of 0.1 g / m ２ Above, 3.0g / m ２ a laminate according to item 1, wherein the adhesive resin layer (B) contains at least one resin selected from the group consisting of acrylic resins, methacrylic resins, vinyl chloride resins, styrene-acrylic resins, styrene-butadiene resins, styrene-isoprene resins, polycarbonate resins, urea resins, melamine resins, epoxy resins, phenolic resins, urethane resins, diallyl phthalate resins, and imine resins; and a laminate according to item 1 or 2, wherein the copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate has a weight-average molecular weight of 250,000 to 650,000 and an average content of 3-hydroxyhexanoate of 6 to 20 mol%. [Item 4] The laminate according to any one of Items 1 to 3, wherein the copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate comprises a first melting point component having a melting point of 60°C or higher but lower than 90°C and a second melting point component having a melting point of 140°C or higher but lower than 170°C. [Item 5] The laminate according to any one of Items 1 to 4, wherein the substrate layer is paper. [Item 6] A method for producing the laminate according to any one of Items 1 to 5, comprising: a first step of forming the adhesive resin layer (B) on at least one surface of the substrate layer by a coating method; and a second step of forming the resin layer (D) on the surface of the adhesive resin layer (B) by an extrusion lamination method or a thermal lamination method. [Item 7] The production method according to Item 6, wherein the first step and the second step are carried out successively. [Item 8] A molded product comprising the laminate according to any one of Items 1 to 5.

[0067] The present invention will be specifically explained below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0068] [Production Examples] (Method of Preparing Coating Liquid) Coating liquid 1: An aqueous emulsion containing an acrylic resin, Gemlac (registered trademark, manufactured by Kaneka Corporation), having an average particle size of 50 nm and a solid content concentration of 30 wt % was prepared.

[0069] Coating liquid 2: An aqueous emulsion (100 parts by weight) containing Gemlac (registered trademark, manufactured by Kaneka Corporation), an acrylic resin having an average particle size of 50 nm and a solid content concentration of 30 wt %, was mixed with a 30% aqueous solution (10 parts by weight) containing polyethyleneimine resin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0070] (PHBH Powder) The PHBH powder used was manufactured in accordance with the method described in International Publication No. 2019-142845. The specific formulation is shown below. PHBH powder 1: low-crystalline PHBH powder having a weight-average molecular weight of 590,000 and a ratio of 3HH to the total of 3HB and 3HH in the PHBH of 15 mol%. PHBH powder 2: high-crystalline PHBH powder having a weight-average molecular weight of 600,000 and a ratio of 3HH to the total of 3HB and 3HH in the PHBH of 5.0 mol%. PHBH powder 3: high-crystalline PHBH powder having a weight-average molecular weight of 310,000 and a ratio of 3HH to the total of 3HB and 3HH in the PHBH of 1.5 mol%.

[0071] (Method for measuring the melting point of PHBH pellets) PHBH pellets dried at 60°C were thinly sliced, and 4 to 10 mg of a sample was packed into an aluminum pan. Using a differential scanning calorimeter, the sample was melted by increasing the temperature from 20°C to 180°C at a rate of 10°C / min under a nitrogen stream to obtain a crystalline melting curve. In the obtained crystalline melting curve, the top temperature of the melting peak from 60°C to less than 90°C was defined as the first melting point, and the top temperature of the melting peak from 140°C to less than 170°C was defined as the second melting point.

[0072] (Method for producing PHBH pellets) PHBH pellet 1: PHBH powder 1 (80 parts by weight) was dry-blended with PHBH powder 2 (20 parts by weight), behenic acid amide (0.5 part by weight), and pentaerythritol (1.0 part by weight), and the mixture was melt-kneaded and extruded into strands using a twin-screw extruder at a set temperature of 150°C and a screw rotation speed of 100 rpm. The strands were then passed through hot water at 40°C to solidify them, and cut into pellets. The weight-average molecular weight of the obtained PHBH pellets was measured to be 460,000, the first melting point was 72°C, and the second melting point was 155°C.

[0073] PHBH pellets 2: The PHBH powder 2 (100 parts by weight) was dry-blended with behenamide (0.5 parts by weight) and pentaerythritol (1.0 part by weight), and the mixture was melt-kneaded and extruded into strands using a twin-screw extruder at a set temperature of 150°C and a screw rotation speed of 100 rpm. The strands were then passed through hot water at 40°C to solidify them, and cut into pellets. The weight-average molecular weight of the obtained PHBH pellets was measured to be 420,000, and the second melting point was 153°C.

[0074] PHBH pellet 3: The PHBH powder 3 (100 parts by weight) was dry-blended with behenamide (0.5 parts by weight) and pentaerythritol (1.0 part by weight), and the mixture was melt-kneaded and extruded into strands using a twin-screw extruder at a set temperature of 150°C and a screw rotation speed of 100 rpm. The strands were then passed through hot water at 40°C to solidify them, and cut into pellets. The weight-average molecular weight of the obtained PHBH pellets was measured to be 250,000, and the second melting point was 169°C.

[0075] <Production of laminate by extrusion lamination method> (Example 1) Basis weight 210 g / m ２ The coating liquid 1 was coated onto an A4 size base paper using a bar coater No. 7, and immediately thereafter, the base paper was placed in a hot air oven heated to 100°C for 30 seconds to dry, thereby forming an adhesive resin layer (B) on the paper substrate. The basis weight of the obtained adhesive resin layer (B) was 2.9 g / m ２Subsequently, the PHBH pellets 1 were fed into a single-screw extruder equipped with a T-die, taken up with a cooling roll set at 60°C, and formed into a film having a thickness of 40 µm. The paper substrate with the adhesive resin layer (B) obtained above and the PHBH film were sandwiched so that the heating roll was in contact with the paper side and the cooling roll was in contact with the PHBH film side, and the conditions were adjusted so that the surface temperature of the PHBH film was 170°C, thereby obtaining a laminate comprising, in this order, the paper substrate, the adhesive resin layer (B), and the resin layer (D).

[0076] (Example 2) A laminate was obtained in the same manner as in Example 1, except that the coating liquid 1 was applied using a bar coater No. 4. The basis weight of the adhesive resin layer (B) was 1.2 g / m ２ It was.

[0077] (Example 3) A laminate was obtained in the same manner as in Example 1, except that the coating liquid 1 was applied using a bar coater No. 1. The basis weight of the adhesive resin layer (B) was 0.1 g / m ２ It was.

[0078] Example 4 A laminate was obtained in the same manner as in Example 1, except that the thickness of the PHBH film was changed to 25 μm.

[0079] Example 5 A laminate was obtained in the same manner as in Example 2, except that the adhesive resin layer (B) was formed using the coating liquid 2.

[0080] Comparative Example 1 A laminate containing a paper substrate and a resin layer (D) without the adhesive resin layer (B) was obtained in the same manner as in Example 1, except that a PHBH film was extrusion laminated to a base paper not having the adhesive resin layer (B).

[0081] Comparative Example 2 A laminate was obtained in the same manner as in Example 1, except that the thickness of the PHBH film was changed to 10 μm.

[0082] (Comparative Example 3) A laminate was obtained in the same manner as in Example 1, except that the coating liquid 1 was applied using a bar coater No. 14. The basis weight of the adhesive resin layer (B) was 6.0 g / m ２ It was.

[0083] Comparative Example 4 A laminate was obtained in the same manner as in Example 1, except that PHBH pellets 2 were used instead of PHBH pellets 1.

[0084] Comparative Example 5 A laminate was obtained in the same manner as in Example 1, except that PHBH pellets 3 were used instead of PHBH pellets 1.

[0085] [Evaluation Method] Evaluations in the examples and comparative examples were carried out by the following methods.

[0086] (Evaluation of Laminate Strength) A laminate strength test was conducted on the day after extrusion lamination. Specifically, a thin cross-cut was made on the resin layer (D) surface of the obtained laminate with a cutter blade, and Nichiban No. CT-17 tape was firmly attached to the cut portion, and then gently peeled off by hand to create a starting point. A piece was then cut out to a width of 15 mm, and the peeled laminate layer and paper were gripped with a jig so that they were at an angle of 180°, and a peel strength test was conducted. The tensile speed was 200 mm / min. A Shimadzu Autograph EZ-LX (manufactured by Shimadzu Corporation) was used as a peel tester.

[0087] <Evaluation> ◯: 3.0 N / 15 mm or more Δ: 2.5 N / 15 mm or more and less than 3.0 N / 15 mm ×: less than 2.0 N / 15 mm If the evaluation result is ◯ or Δ, it can be said that the laminate strength is sufficient.

[0088] (Evaluation of drying property) Basis weight 210 g / m ２ An A4 size base paper was coated under the conditions described in the Examples and Comparative Examples to form an adhesive resin layer (B), and then heated in a hot air oven at 100°C for 30 seconds, and then removed, and the surface condition of the adhesive resin layer (B) was observed.

[0089] <Evaluation> ○: The surface is not wet and a coating film is sufficiently formed △: The surface is slightly wet, but a coating film is sufficiently formed ×: Puddles have formed on the surface and a coating film has not been sufficiently formed If the above evaluation result is ○ or △, drying and coating film formation in a typical papermaking process are possible.

[0090] (Measurement of basis weight of adhesive resin layer (B)) The papers with adhesive resin layer (B) obtained in the Examples and Comparative Examples were thoroughly dried for 10 minutes in a hot air oven heated to 100°C, and then aged for one week under conditions of 25°C and 60% humidity. Thereafter, a piece of 10 cm x 10 cm was cut out and weighed, and the weight value was subtracted from the weight value by the weight of the base paper, and multiplied by 100 to obtain the basis weight value of the adhesive resin layer (B).

[0091]

[0092] <Results> From Table 1, it can be seen that in each Example, the substrate layer (A) and the resin layer (D) containing the copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate were bonded with sufficient strength via the adhesive resin layer (B), and that the drying properties after coating of the adhesive resin layer (B) were also good. On the other hand, the adhesion was insufficient in Comparative Examples 1, 2, 4, and 5, and the drying properties were poor in Comparative Example 3, which shows that the comparative examples did not achieve both adhesion and drying properties.

[0093] 1 Laminate 2 Base material layer 3 Adhesive resin layer (B) 4 Resin layer (D)

Claims

1. A laminate comprising, in this order, a substrate layer (A), an adhesive resin layer (B), and a resin layer (D) containing a copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate, The adhesive resin layer (B) has a basis weight of 0.1 g / m ２ Above, 3.0g / m ２ is less than The copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate contains a first melting point component having a melting point of 60°C or more and less than 90°C, and a second melting point component having a melting point of 140°C or more and less than 170°C, the average content of 3-hydroxyhexanoate in the copolymer (C) is 6 mol% or more; The thickness of the resin layer (D) is 20 μm or more and less than 100 μm.

2. 2. The laminate according to claim 1, wherein the adhesive resin layer (B) contains at least one resin selected from the group consisting of acrylic resins, methacrylic resins, vinyl chloride resins, styrene-acrylic resins, styrene-butadiene resins, styrene-isoprene resins, polycarbonate resins, urea resins, melamine resins, epoxy resins, phenolic resins, urethane resins, diallyl phthalate resins, and imine resins.

3. The copolymer (C) of 3-hydroxybutyrate and 3-hydroxyhexanoate has a weight average molecular weight of 250,000 to 650,000 and an average content of 3-hydroxyhexanoate of 6 to 20 mol%.

4. The laminate according to claim 1 or 2, wherein the substrate layer is paper.

5. A method for producing the laminate according to claim 1 or 2, comprising: A manufacturing method comprising: a first step of forming the adhesive resin layer (B) on at least one surface of the base material layer by a coating method; and a second step of forming the resin layer (D) on the surface of the adhesive resin layer (B) by an extrusion lamination method or a thermal lamination method.

6. The manufacturing method according to claim 5 , wherein the first step and the second step are carried out successively.

7. A molded article comprising the laminate according to claim 1 or 2.