Method for manufacturing a laminate

Abstract

A method for producing a laminate having a substrate layer and a resin layer formed on at least one side of the substrate layer, the resin layer containing a poly(3-hydroxybutyrate)-based resin and having a weight per unit area (dry weight) of 15 to 50 g / m 2 On the surface of the substrate layer, an aqueous dispersion (HB-A) containing a poly(3-hydroxybutyrate)-based resin (a1) and a dispersant (a2) containing a water-soluble high molecule is applied to form a coating film (a), and heating is performed to form a coating layer (A) having a weight per unit area (dry weight) of 0.5 to 10 g / m 2 On the surface of the coating layer (A), an aqueous dispersion (HB-B) containing a poly(3-hydroxybutyrate)-based resin (b1) and a dispersant (b2) containing a water-soluble high molecule is applied to form a coating film (b), and heating is performed to form a coating layer (B). The content of the dispersant (b2) containing a water-soluble high molecule is 0 to 0.5 parts by weight per 100 parts by weight of (b1).

Description

TECHNICAL FIELD

[0001] The present application relates to a method for producing a laminate having a substrate layer, and a resin layer containing a poly(3-hydroxybutyrate)-based resin formed on at least one side of the substrate layer. BACKGROUND

[0002] In recent years, environmental problems caused by waste plastics have been attracting attention. Among them, ocean pollution caused by waste plastics is very serious, and the popularization of biodegradable plastics that can be decomposed in the natural environment is expected.

[0003] As such biodegradable plastics, various biodegradable plastics are known, among which, poly(3-hydroxybutyrate)-based resins are thermoplastic polyesters produced and accumulated in the cells of many microbial species as energy storage substances, and are materials that can be biodegraded not only in soil but also in seawater, and thus are attracting attention as raw materials for solving the above problems.

[0004] A laminate in which a layer containing a poly(3-hydroxybutyrate)-based resin is laminated with a substrate layer having biodegradability such as paper is a material in which both the resin and the substrate have excellent biodegradability, and thus is extremely promising from the viewpoint of environmental protection.

[0005] Conventionally, a laminate in which an aqueous dispersion of a resin is applied to paper is known, and as a laminate containing the above-mentioned poly(3-hydroxybutyrate)-based resin, a laminate obtained by applying an aqueous dispersion containing a polyhydroxybutyric acid / polyhydroxyvaleric acid copolymer, polyvinyl alcohol, and a polycarboxylic acid salt-based dispersant to a substrate and performing heat treatment is proposed (see Patent Document 1).

[0006] PRIOR ART DOCUMENTS

[0007] PATENT DOCUMENT

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2-222421 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] Regarding the method for producing a laminate in which a poly(3-hydroxybutyrate)-based resin layer is laminated on a substrate described in Patent Document 1, a large amount of a water-soluble polymer such as polyvinyl alcohol is required to be used when the poly(3-hydroxybutyrate)-based resin is dispersed in water, and thus there is a problem that the water resistance of the laminate is insufficient.

[0011] On the other hand, the present inventors and others have found that, when an aqueous dispersion liquid in which the amount of a water-soluble polymer-based dispersant is reduced is used, and a laminate in which the average dry weight per unit area of the resin layer (sometimes referred to as the weight per unit area) is increased in order to improve the barrier properties against water and oil is desired, peeling of the coating layer from the substrate during the heating treatment after the aqueous dispersion liquid is applied becomes a new problem.

[0012] In view of the above, the present application aims to provide a production method in which an aqueous dispersion liquid in which the amount of a water-soluble polymer-based dispersant that is a cause of reduction in water resistance of the resin layer is reduced is used, peeling of the resin layer from the substrate layer, or peeling of the coating layer from the substrate layer during production is inhibited, and a resin layer having a high weight per unit area is formed, in the production of a laminate including a substrate and a poly(3-hydroxybutyrate)-based resin layer, in which an aqueous dispersion liquid is applied to the substrate.

[0013] Production method solving the problem

[0014] The present inventors and others have found that, by applying a poly(3-hydroxybutyrate)-based resin aqueous dispersion liquid containing a specific amount of a dispersant to a substrate layer to form a first layer at a specific weight per unit area, and then forming a second layer, the above problem can be solved, and the present application has been completed.

[0015] That is, the present application relates to a production method of a laminate having a substrate layer, and a resin layer formed on at least one face of the substrate layer, the resin layer containing a poly(3-hydroxybutyrate)-based resin, and having an average weight per unit area (dry weight) of 15 to 50 g / m 2 ,

[0016] The production method includes at least sequentially performing the following process (i) and process (ii):

[0017] Process (i), applying an aqueous dispersion liquid (HB-A) to the surface of the substrate layer to form a coating film (a), and heating the coating film (a) to form a coating layer (A) having an average weight per unit area (dry weight) of 0.5 to 10 g / m 2 , the aqueous dispersion liquid (HB-A) containing a poly(3-hydroxybutyrate)-based resin (al), and a dispersant (a2) containing a water-soluble polymer, and the content of the dispersant (a2) containing a water-soluble polymer is 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (al);

[0018] Process (ii) forming a coating film (b) by applying an aqueous dispersion (HB-B) containing a poly(3-hydroxybutyrate)-based resin (bl) and a dispersant (b2) containing a water-soluble high molecular weight polymer to the surface of the coating (A) on one side, and heating the coating film (b) to form a coating (B), the content of the dispersant (b2) containing a water-soluble high molecular weight polymer being 0 to 0.5 parts by weight per 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (bl).

[0019] Further, the present application also relates to a laminate having a substrate layer, and a resin layer formed on at least one side of the substrate layer, the resin layer containing a poly(3-hydroxybutyrate)-based resin, and the average weight per unit area (dry weight) being 15 to 50 g / m 2 ,

[0020] The laminate sequentially contains a substrate layer, a coating (A) and a coating (B),

[0021] The coating (A) contains a poly(3-hydroxybutyrate)-based resin (al) and a dispersant (a2) containing a water-soluble high molecular weight polymer, and the average weight per unit area (dry weight) is 0.5 to 10 g / m 2 , the content of the dispersant (a2) containing a water-soluble high molecular weight polymer being 0.1 to 2.0 parts by weight per 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (al),

[0022] The coating (B) contains a poly(3-hydroxybutyrate)-based resin (bl) and a dispersant (b2) containing a water-soluble high molecular weight polymer, and the content of the dispersant (b2) containing a water-soluble high molecular weight polymer is 0 to 0.5 parts by weight per 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (bl).

[0023] Effects of the Invention

[0024] According to the present application, in a method of manufacturing a laminate containing a substrate and a poly(3-hydroxybutyrate)-based resin layer by applying an aqueous dispersion containing a poly(3-hydroxybutyrate)-based resin to a substrate, an aqueous dispersion in which the amount of a water-soluble high molecular weight polymer-based dispersant, which is a cause of reduction in water resistance of the resin layer, is reduced is used, and a manufacturing method in which peeling of a coating from a substrate layer at the time of manufacturing is inhibited and a resin layer having a high weight per unit area can be formed can be provided.

[0025] According to a preferred mode of the present application, a manufacturing method of a laminate having a resin layer with excellent water resistance on a paper substrate can be provided, and by using the manufacturing method, a laminate which can be suitably used as a container for holding a liquid such as a paper cup for beverages can be provided. DETAILED DESCRIPTION

[0026] Hereinafter, an embodiment of the present application will be described, but the present application is not limited to the following embodiment.

[0027] (Laminate)

[0028] The laminate of one embodiment of the present application has a substrate layer, and a resin layer formed on at least one side of the substrate layer, wherein the resin layer contains a poly(3-hydroxybutyrate)-based resin.

[0029] The resin layer is formed by applying an aqueous dispersion liquid containing a poly(3-hydroxybutyrate)-based resin to the surface of the substrate layer and drying by heating.

[0030] The resin layer can be laminated on only one side of the substrate layer, or can be laminated on both sides. Further, the resin layer can be laminated on the substrate layer with other layers interposed therebetween, or can be directly laminated on the substrate layer without other layers interposed therebetween. Other layers can be further laminated on the resin layer.

[0031] (Substrate layer)

[0032] The substrate layer is not particularly limited as long as it is a layer on which a resin layer can be laminated, and is preferably a layer having biodegradability. By making the substrate layer a layer having biodegradability, the entire laminate including the resin layer has biodegradability, which is more advantageous as a raw material for solving the problem of ocean pollution.

[0033] Further, from the viewpoint of preventing the aqueous dispersion liquid from flowing over the surface to form a coating film with uneven thickness, the substrate layer is preferably water-absorbing.

[0034] As the substrate layer having biodegradability, there is no particular limitation, and examples include paper (main component is cellulose), cellophane, cellulose ester; polyvinyl alcohol, polyamino acid, polyglycolic acid, pullulan, or a material in which aluminum, silicon dioxide, or the like is vapor-deposited on these substrates. Among them, paper is preferable from the viewpoint of excellent heat resistance and low cost.

[0035] The type of paper is not particularly limited, and examples include paper cup raw paper, kraft paper, full-bleached kraft paper, coated paper, thin-layer paper, glassine paper, and board paper. The type of paper can be appropriately selected depending on the purpose of the present laminate. Water-resistant agents, water-repellent agents, inorganic substances, or the like can be added to the paper as needed, and surface treatment such as oxygen barrier layer coating, water vapor barrier coating, or the like can be performed.

[0036] The average weight per unit area of the substrate (unit area weight of the substrate) is not particularly limited, and is preferably 50 to 400 g / m 2 , more preferably 100 to 300 g / m 2, further preferably 150 to 250 g / m 2 By setting the weight per unit area of the substrate to this range, curling of the laminate that occurs when a resin layer is later laminated at the weight per unit area described below can be suppressed.

[0037] The substrate layer described above can be subjected to surface treatment such as corona treatment, flame treatment, adhesion coating treatment, or the like. These surface treatments can be performed individually or in combination with multiple surface treatments.

[0038] (resin layer and / or coating layer)

[0039] The resin layer and the coating layer included in the laminate of one embodiment of the present application each contain at least a poly(3-hydroxybutyrate)-based resin. In this specification, a poly(3-hydroxybutyrate)-based resin (hereinafter also referred to as a P3HB-based resin) is an aliphatic polyester resin containing 3-hydroxybutyrate as a repeating unit.

[0040] The P3HB-based resin can be poly(3-hydroxybutyrate) containing only 3-hydroxybutyrate as a repeating unit, or can be a copolymer of 3-hydroxybutyrate and another hydroxyalkanoate.

[0041] The P3HB-based resin can be a mixture of a homopolymer and one or more copolymers, or can be a mixture of two or more copolymers. The form of copolymerization is not particularly limited and can be random copolymerization, alternating copolymerization, block copolymerization, graft copolymerization, or the like.

[0042] As the P3HB-based resin, for example, poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HB3HV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (P3HB3HO), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate) (P3HB3HOD), poly(3-hydroxybutyrate-co-3-hydroxydecanoate) (P3HB3HD), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P3HB3HV3HH), or the like can be given. Of these, from the viewpoint of easy industrial production, P3HB, P3HB3HH, P3HB3HV, and P3HB4HB are preferable.

[0043] Further, by changing the composition ratio of the repeating units, the melting point and crystallinity change, and as a result, the Young's modulus, heat resistance, and the like can be changed, and the properties between polypropylene and polyethylene can be imparted. Further, as described above, it is industrially easy to produce, and is a useful plastic in terms of properties. From such a viewpoint, P3HB3HH, which is a copolymer of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid, is more preferable. Further, from the viewpoint of being able to lower the melting point and perform molding processing at low temperatures, P3HB3HH is preferable.

[0044] In the present embodiment, the P3HB-based resin preferably contains at least one P3HB3HH, and particularly preferably contains at least two poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having different proportions of the constituent monomers. Further, it is also preferable to contain at least one P3HB3HH and P3HB.

[0045] The P3HB-based resin can be produced by a microorganism. As the microorganism, any microorganism having the ability to produce a P3HB-based resin can be used without particular limitation. For example, as a P3HB-producing bacterium, the first P3HB-producing bacterium was Bacillus megaterium discovered in 1925, and other natural microorganisms such as Cupriavidus necator (old classification: Alcaligenes eutrophus, Ralstonia eutropha), Alcaligenes latus, and the like can be listed. Among these microorganisms, it is known that P3HB is accumulated in the bacterial cells.

[0046] Further, as a P3HB3HV and P3HB3HH-producing bacterium, Aeromonas caviae is known as a P3HB3HV and P3HB3HH-producing bacterium, and Alcaligenes eutrophus is known as a P3HB4HB-producing bacterium. In particular, with respect to P3HB3HH, in order to improve the productivity of P3HB3HH, Alcaligenes eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038) into which a gene of a P3HA synthase group has been introduced (T. Fukui, Y. Doi, J. Bacteriol., 179, p4821-4830 (1997)), and the like are more preferable. A bacterial cell in which P3HB3HH is accumulated in the bacterial cells by culturing these microorganisms under appropriate conditions can be used. Further, in addition to the above, a genetically recombined microorganism into which various P3HB-based resin synthesis-related genes have been introduced depending on the P3HB-based resin to be produced can be used, and optimization of the culture conditions including the types of substrates can be performed.

[0047] In addition, P3HB3HH can also be produced by the method described in International Publication No. 2010 / 013483, for example. As a commercially available product of P3HB3HH, for example, "Tokumika Biodegradable Polymer PHBH (registered trademark)" and the like manufactured by Tokumika Corporation can be mentioned.

[0048] The composition ratio of each constituent monomer in P3HB3HH is preferably 3HB / 3HH = 95 to 70 / 5 to 30 (mole % / mole %), more preferably 3HB / 3HH = 90 to 82 / 10 to 18 (mole % / mole %). When the composition ratio of 3HH in P3HB3HH is 5 mole % or more, the melting point can be reduced with respect to the thermal decomposition temperature of the resin, 180°C, and the thermal decomposition of the resin layer in the heating process can be easily suppressed. In addition, the crystallization speed of P3HB3HH having a composition ratio of 3HH of 30 mole % or less does not become too slow, and production is easier. Note that the composition ratio of 3HH can be measured by NMR measurement of P3HB3HH.

[0049] P3HB3HH having a composition ratio of 3HH of 5 to 30 mole % can be obtained by cultivation and can be used as a single P3HB-based resin, or can be used in combination with P3HB3HH having a composition ratio of 3HH of less than 5 mole % or P3HB (a homopolymer of 3HB). By this combination, a resin having the melting properties described later can be easily formed compared to the case of using alone. The composition ratio of 3HH in P3HB3HH having a composition ratio of 3HH of less than 5 mole % is preferably 3 mole % or less, more preferably 2 mole % or less, and further preferably 1 mole % or less.

[0050] The blending amount of P3HB3HH having a composition ratio of 3HH of less than 5 mole % or P3HB is not particularly limited and is preferably 1 to 50% by weight, more preferably 3 to 30% by weight, further preferably 4 to 20% by weight, and particularly preferably 5 to 15% by weight, with respect to the total of the P3HB-based resin contained in the above-described resin layer and / or the above-described coating layer.

[0051] The microorganism produces P3HB3HH as a random copolymer. Adjustment of the 3HH composition ratio can be performed by selection of the bacterial cells, selection of the carbon source as a raw material, blending of P3HB3HH having different 3HH composition ratios, blending of a homopolymer of 3HB, and the like, for example.

[0052] According to the present embodiment, the weight average molecular weight of the P3HB-based resin is preferably 100,000 or more, more preferably 150,000 or more, and further preferably 200,000 or more. When the weight average molecular weight of the P3HB-based resin is 100,000 or more, the mechanical strength of the resin layer and / or the coating layer is high, and the resin layer and / or the coating layer are less likely to be cracked even when the laminate is bent or the like during 2-step processing.

[0053] In addition, the weight average molecular weight of the P3HB-based resin is preferably 700,000 or less, more preferably 600,000 or less, and further preferably 550,000 or less. When the weight average molecular weight of the P3HB-based resin is 700,000 or less, the melt viscosity of the resin does not become excessively high, and the fusion between the resin particles during the heating step described later is facilitated, and the generation of pores in the resin layer and / or the coating layer can be suppressed.

[0054] Note that the weight average molecular weight of the P3HB-based resin can be measured by a gel permeation chromatograph (GPC) (Shodex GPC-101 manufactured by Showa Denko K.K.), using polystyrene gel (Shodex K-804 manufactured by Showa Denko K.K.) in the column and chloroform as the mobile phase, as the molecular weight converted to polystyrene.

[0055] According to the present embodiment, the P3HB-based resin described above preferably has a melting property in which, in a crystalline melting curve obtained by differential scanning calorimetry, at least one peak top temperature (Tma) is present in the range of 100 to 150°C, and at least one peak top temperature (Tmb) is present in the range of 150 to 170°C, and the temperature difference between Tma and Tmb is 10°C or more. By having a melting point peak in the relatively high temperature range of 150 to 170°C in the P3HB-based resin described above, the resin crystallization having Tmb functions as a crystallization nucleus, and thus the crystallization of the P3HB-based resin after the heating step is accelerated, and the productivity of the laminate is improved. In addition, the blocking of the substrate layer and the resin layer or the substrate layer and the coating layer caused by the adhesion of the substrate layer and the resin layer or the substrate layer and the coating layer when the laminate is continuously manufactured and wound into a roll shape can be reduced.

[0056] The temperature difference between Tma and Tmb is preferably 15°C or more, more preferably 20°C or more, and further preferably 25°C or more. When the temperature difference is 10°C or more, the blocking of the roll-shaped laminate can be further reduced. The upper limit of the temperature difference between Tma and Tmb is not particularly limited, and from the viewpoint of ease of manufacture, for example, it is 60°C or less, and more preferably 50°C or less.

[0057] In the present application, the peak top temperature of the crystalline melting curve in differential scanning calorimetry is defined as follows. 2 to 5 mg of the resin to be measured is filled into an aluminum pan, and a differential scanning calorimeter is used to raise the temperature from 20°C to 190°C at a rate of 10°C / min under a nitrogen stream, and the resin is melted to obtain a crystalline melting curve. In the obtained crystalline melting curve, the peak top temperature of the melting point peak present in the range of 100 to 150°C is taken as Tma, and the peak top temperature of the melting point peak present in the range of 150 to 170°C is taken as Tmb. In the case where a plurality of melting point peaks are confirmed in the range of 100 to 150°C, the peak top temperature of the peak with the highest height is taken as Tma, and in the case where a plurality of melting point peaks are confirmed in the range of 150 to 170°C, the peak top temperature of the peak with the highest height is taken as Tmb.

[0058] The resin layer and / or the coating layer can contain one or more resins other than the P3HB-based resin within a range where the effects of the present application are exerted. As such other resins, for example, aliphatic polyester-based resins such as polybutylene succinate, polybutylene succinate adipate, polycaprolactone, polylactic acid, and the like, aliphatic aromatic polyester-based resins such as polybutylene adipate terephthalate, polybutylene sebacate terephthalate, polybutylene azelate terephthalate, and the like can be exemplified. In order to ensure the biodegradability of the resin layer, the amount of addition of these resins is preferably 20 parts by weight or less relative to 100 parts by weight of the P3HB-based resin. The resin layer can contain resins other than the P3HB-based resin.

[0059] The resin layer and / or the coating layer can contain additives generally used in the technical field within a range where the effects of the present application are exerted. As such additives, for example, inorganic fillers such as talc, calcium carbonate, mica, silica, titanium oxide, alumina, kaolin, and the like, organic fillers such as rice husks, wood powder, waste paper such as newspapers, various starches, cellulose, and the like, coloring agents such as pigments, dyes, and the like, odor absorbers such as activated carbon, zeolite, and the like, flavorings such as vanillin, dextrin, and the like, plasticizers, antioxidants, weather resistance improvers, ultraviolet absorbers, crystallization nucleating agents, lubricants, release agents, water repellents, antibacterial agents, sliding property improvers, tackifiers, fillers, medicaments, and the like can be exemplified. The additives can be contained singly or in combination of two or more. The content of these additives can be appropriately set by those skilled in the art according to the purpose of use.

[0060] According to one embodiment of the present application, the resin layer is composed of the coating layers (A) and (B), or the coating layers (A), (C) and (B) stacked in this order from the side of the base material layer. The respective P3HB-based resins contained in these coating layers (A) and (B), or (A), (B) and (C) can be the same as or different from each other. In addition, the person skilled in the art can appropriately set the resin other than the P3HB-based resin and the additive as an arbitrary component in each layer in accordance with the purpose of use.

[0061] The resin layer can have a layer other than the coating layers (A), (B) and (C).

[0062] The average weight per unit area of the resin layer (the total dry weight of all the coating layers containing the poly(3-hydroxybutyrate)-based resin, which means the total dry weight of all the coating layers on one side. Sometimes referred to as the weight per unit area) is preferably 15 to 50 g / m2, more preferably 20 to 40 g / m2, and particularly preferably 25 to 35 g / m2. The average weight per unit area of the resin layer is the total dry weight of all the coating layers containing the poly(3-hydroxybutyrate)-based resin on one side. 2 2 2 When the average weight per unit area of the resin layer is within the above range, the resin layer can have the following advantages: prevention of defects such as pores, strength to the extent that can withstand use, and efficient display of functions such as water resistance. Note that the average weight per unit area of the resin layer can be measured by the method described in the examples (Method for measuring the weight per unit area of the resin).

[0063] (Aqueous dispersion)

[0064] The aqueous dispersion containing the poly(3-hydroxybutyrate)-based resin is not particularly limited and can be produced by the following method. First, the P3HB-based resin is produced in the microbial cell, and then the microbial cell containing the P3HB-based resin is crushed in the state of an aqueous dispersion, and the P3HB-based resin in the microbial cell is separated.

[0065] ​​Generally, in the recovery of P3HB-based resin from microbial cells, a method of dissolving P3HB-based resin with an organic solvent such as chloroform, and precipitating P3HB-based resin with a P3HB-based resin-insoluble solvent such as methanol or hexane, and the like can be used. However, in this method, the obtained P3HB-based resin cannot be made into fine particles, and a process of making P3HB-based resin into fine particles needs to be added, which is not economical. In contrast, by a process of breaking microbial cells containing P3HB-based resin in an aqueous dispersion state to separate P3HB-based resin in the cells, an aqueous dispersion of P3HB-based resin fine particles, which has a fine particle diameter to a considerable extent, can be obtained for P3HB-based resin produced in microbial cells.

[0066] In the process of breaking microbial cells containing P3HB-based resin in an aqueous dispersion state to separate P3HB-based resin in the cells, it is preferable to simultaneously perform breaking and alkali addition while stirring microbial cells containing P3HB-based resin. This method has the following advantages: (1) it can prevent an increase in viscosity of the dispersion due to components other than P3HB-based resin leaking from microbial cells; (2) by preventing an increase in viscosity of the cell dispersion, control of pH can be performed, and further, treatment can be performed at a low alkali concentration by continuously or intermittently adding alkali; and (3) it can suppress a decrease in molecular weight of P3HB-based resin, and high-purity P3HB-based resin can be separated.

[0067] The pH of the cell dispersion after addition of alkali is preferably 9 to 13.5. When the pH is 9 or higher, P3HB-based resin is easily separated from the cells, and when the pH is 13.5 or lower, decomposition of P3HB-based resin is suppressed.

[0068] The breaking of microbial cells can be performed by a method of breaking with ultrasonic waves, a method of using an emulsifying disperser, a high-pressure homogenizer, a mill, or the like. Among these, from the viewpoint of efficiently breaking nucleic acids, which are a main cause of an increase in viscosity by alkali treatment to dissolve P3HB-based resin from the cells, and sufficiently dispersing cell walls, cell membranes, insoluble proteins, and other insoluble substances other than P3HB-based resin, an emulsifying disperser such as a Silverson Mixer (manufactured by Silverson), a ClearMix (manufactured by M Technique), an Ebara Milder (manufactured by Ebara), or the like is preferably used, but is not limited thereto.

[0069] In addition, the temperature conditions at the time of breaking microbial cells and adding alkali are preferably in the range of room temperature to 50°C. When the above temperature conditions exceed 50°C, decomposition of P3HB-based resin easily occurs, and thus it is preferable to be around room temperature. In addition, when it is desired to be lower than room temperature, a cooling operation is required, and thus it is not economical.

[0070] The precipitate is obtained by centrifugal separation from a dispersion liquid obtained by subjecting microbial cells to crushing and alkali treatment, the precipitate is subjected to water washing, methanol washing as necessary, and finally an appropriate amount of water is added, to obtain an aqueous dispersion liquid of the P3HB-based resin containing a desired solid content.

[0071] A mechanical shearing can be applied to the obtained aqueous dispersion liquid to separate a part of the aggregated P3HB-based resin particles from each other. The application of the mechanical shearing can obtain an aqueous dispersion liquid of the P3HB-based resin substantially free of aggregates and containing uniform particle diameters, which is preferable from this point of view. The mechanical shearing of the aqueous dispersion liquid can be performed using, for example, a blender, a homogenizer, ultrasonic waves, and the like. At this time, the aggregation of the P3HB-based resin particles is not very strong, and from the viewpoint of convenience, it is preferable to use a general blender equipped with a stirring paddle.

[0072] The solid content of the P3HB-based resin in the above aqueous dispersion liquid is preferably 25 to 65% by weight, more preferably 30 to 55% by weight, and particularly preferably 35 to 50% by weight. When the solid content of the P3HB-based resin in the above aqueous dispersion liquid is within the above range, the viscosity of the aqueous dispersion liquid does not become too high, uniform coating can be performed, and the desired film thickness can be maintained, whereby the effect of not easily causing film defects can be exerted.

[0073] In addition, the solid content of the P3HB-based resin in each of the aqueous dispersion liquids can be the same as or different from each other, and can be appropriately set by those skilled in the art depending on the purpose of use.

[0074] From the viewpoint of balancing the productivity of the P3HB-based resin and the uniformity at the time of coating, the average particle diameter of the P3HB-based resin in the above aqueous dispersion liquid is, for example, 0.1 to 50 μm, preferably 0.5 to 30 μm, and more preferably 0.8 to 20 μm. By making the average particle diameter 0.1 μm or more, the P3HB-based resin can be easily obtained by any of the microbial production and chemical synthesis methods. By making the average particle diameter 50 μm or less, coating unevenness can be avoided.

[0075] Note that the average particle diameter of the P3HB-based resin in the aqueous dispersion liquid can be measured using a general particle size meter such as a MICROTRAC particle size meter (manufactured by NIKKISO CO., LTD., FRA), and the aqueous dispersion liquid containing the P3HB-based resin is adjusted to a given concentration, and the particle diameter corresponding to 50% of the cumulative amount of all particles in a normal distribution is calculated.

[0076] As the water-soluble polymer dispersant that can be used in the present embodiment, for example, polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, sulfonated-modified polyvinyl alcohol, polyvinyl alcohol derivatives such as ethylene-modified polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose derivatives, starch, oxidized starch or etherified starch, starch derivatives, chitin, chitosan, casein, gum arabic, and the like can be listed, and these can be used alone or in combination of two or more.

[0077] The amount of the water-soluble polymer dispersant (a2) used in the above-mentioned aqueous poly(3-hydroxybutyrate) resin dispersion (HB-A) is preferably 0.1 to 2.0 parts by weight, more preferably 0.3 to 1.8 parts by weight, and particularly preferably 1.0 to 1.5 parts by weight, relative to 100 parts by weight of the poly(3-hydroxybutyrate) resin (a1) contained in the aqueous dispersion (HB-A). By setting the range, in addition to the fact that the coating layer (A) can be inhibited from peeling from the substrate layer by the heat treatment after the coating of the aqueous dispersion (HB-A), the adhesion strength of the substrate layer to the poly(3-hydroxybutyrate) resin after the heat treatment can also be favorably maintained.

[0078] The above-mentioned aqueous poly(3-hydroxybutyrate) resin dispersion (HB-B) can be substantially free of the water-soluble polymer dispersant (b2), or can contain the water-soluble polymer dispersant (b2) within a range that does not impair the water resistance of the coating layer (B) in order to inhibit the coagulation of the poly(3-hydroxybutyrate) resin (b1) contained in the aqueous dispersion (HB-B) and stabilize the dispersion.

[0079] The amount of the water-soluble polymer dispersant (b2) is preferably 0 to 0.5 parts by weight, relative to 100 parts by weight of the poly(3-hydroxybutyrate) resin (b1) contained in the aqueous dispersion (HB-B). By setting the range, the coating amount of the aqueous dispersion (HB-B) can be increased without impairing the water resistance of the coating layer (B), and the weight per unit area of the coating layer (B) and the resin layer can be increased. In the case where the water-soluble polymer dispersant (b2) is used, the above-mentioned amount is preferably 0.1 to 0.5 parts by weight. The upper limit can be 0.4 parts by weight or less, and can be 0.3 parts by weight or less.

[0080] Note that, in the present application, substantially free of the water-soluble polymer dispersant means that the water-soluble polymer dispersant is not added in order to obtain the effect of stabilizing the dispersion of the resin.

[0081] The aqueous dispersion (HB-A) and / or (HB-B) described above can contain a dispersant other than the water-soluble polymer as needed. The kind of the dispersant other than the water-soluble polymer described above is not particularly limited, and examples thereof include anionic surfactants such as sodium dodecyl sulfate and sodium oleate, cationic surfactants such as dodecyltrimethylammonium chloride, nonionic surfactants such as glycerol fatty acid ester and sorbitan fatty acid ester, and the like, which can be used alone or in combination of two or more.

[0082] The aqueous dispersion (HB-C) of poly(3-hydroxybutyrate)-based resin is an aqueous dispersion that forms a coating layer (C) which becomes an intermediate layer of the coating layer (A) and the coating layer (B) described above. The dispersant contained in the aqueous dispersion (HB-C) can be the same as or different from the dispersants contained in the aqueous dispersions (HB-A) and (HB-B), and can be appropriately selected depending on the coating method.

[0083] The dispersant described above can be added to the aqueous dispersion after the microbial cell is broken and subjected to alkali treatment, or after centrifugation and water washing. In the case where methanol washing is performed, the dispersant can be added after the methanol washing, before or after the solid content concentration of the P3HB-based resin is adjusted by adding an appropriate amount of water.

[0084] (Method for manufacturing laminate)

[0085] The manufacturing method of one embodiment of the present application is performed by the following method: after the aqueous dispersion (HB-A) described above is applied to one side or both sides of the substrate layer, heating, drying, and film formation are performed to form the coating layer (A) of the first layer, and then the aqueous dispersion (HB-B) described above is further applied, and heating, drying, and film formation are performed to form the coating layer (B). By forming the resin layer in several stages in this way, peeling of the substrate from the resin layer is easily suppressed, and the coating layer (B) having excellent water resistance is formed on the topmost surface.

[0086] The average weight per unit area (dry weight: weight per unit area) of the coating layer (A) is preferably 0.5 to 10 g / m 2 , more preferably 1 to 8 g / m 2 , and particularly preferably 3 to 7 g / m 2 . By forming the coating layer having a low weight per unit area on the surface of the substrate and then forming the coating layer (B) (or (B) and (C)), peeling of the resin layer from the substrate layer is suppressed, and a resin layer having a high weight per unit area is formed as a whole.

[0087] The weight per unit area of the coating layer (A) is less than 0.5 g / m 2When the thickness of the coating layer (A) becomes uneven, there is a tendency that the coating layer (B) is peeled from the substrate at the time of applying the aqueous dispersion (HB-B) and performing the heat treatment described later. On the other hand, when the thickness of the coating layer (A) exceeds 10 g / m 2 When the thickness of the coating layer (A) becomes uneven, there is a tendency that the coating layer (B) is peeled from the substrate at the time of applying the aqueous dispersion (HB-B) and performing the heat treatment described later. On the other hand, when the thickness of the coating layer (A) exceeds 10 g / m

[0088] The average weight per unit area (dry weight: weight per unit area) of the coating layer (B) can be appropriately set in consideration of the average weight per unit area of the coating layer (A) so that the average weight per unit area of the resin layer is 15 to 50 g / m 2 When the average weight per unit area of the resin layer exceeds 50 g / m 2 When the average weight per unit area of the resin layer exceeds 50 g / m

[0089] The production method of another mode of the present embodiment can also be implemented by the following method: after forming the above-described coating layer (A) on one side or both sides of the substrate layer, applying the aqueous dispersion (HB-C) containing the poly(3-hydroxybutyrate)-based resin (cl), performing heat, drying, and film formation, and after forming the coating layer (C) as an intermediate layer, forming the above-described coating layer (B). By providing the coating layer (C) as an intermediate layer, the generation of pores can be further suppressed, and the barrier property of the resin layer against water and oil can be more easily ensured.

[0090] The average weight per unit area (dry weight: weight per unit area) of the coating layer (C) is preferably 5 to 10 g / m 2 The formation of the coating layer (C) can be performed by repeating the application of the aqueous dispersion (HB-C), the drying based on heat, and the film formation.

[0091] The method of applying each aqueous dispersion to the substrate is not particularly limited as long as it can substantially form the desired coating layer on the substrate. Known methods such as a spray coating method, a scattering method, a slit coating method, an air knife coating method, a roll coating method, a bar coating method, a doctor blade coating method, a screen printing method, a gravure printing method, and the like can be used alone or in combination. The process of performing the above-described surface treatment such as corona treatment on the substrate can be implemented before applying the above-described aqueous dispersion (HB-A).

[0092] The formation of each coating layer can be performed by heating each coating film formed on the substrate by the application of each aqueous dispersion to a temperature above the melting point of the P3HB-based resin, evaporating water, and causing the P3HB-based resin particles contained in the aqueous dispersion to fuse to each other. The melting point of the above-described P3HB-based resin refers to the peak top temperature of the highest temperature in the crystalline melting curve of the above-described differential scanning calorimetry analysis. For example, in the case where Tma and Tmb are present, it refers to Tmb.

[0093] The heating treatment can be performed using a publicly known heating method, and examples thereof include hot air heating, infrared heating, microwave heating, roll heating, hot plate heating, and the like, which can be used alone or in combination of two or more.

[0094] The heating temperature in the heating treatment can be equal to or higher than the melting point of the P3HB-based resin, and is preferably a temperature that is 10 to 40°C higher than the melting point of the P3HB-based resin, and further preferably a temperature that is 20 to 30°C higher. Specifically, the heating temperature is preferably 160°C or higher, more preferably 165°C or higher, and particularly preferably 170°C or higher. In addition, the heating temperature is preferably 200°C or lower. When the heating temperature is 200°C or lower, it is possible to avoid problems such as a decrease in mechanical strength and breakage of the laminate caused by excessive drying of the base material layer and thermal decomposition of the P3HB-based resin.

[0095] Note that the heating temperature in the heating treatment is not the temperature actually exhibited by the laminate, but is the set temperature of the drying furnace, roll, or the like used in the heating treatment.

[0096] The heating time in the heating treatment can be appropriately set in consideration of the drying of the coated film and the molten state of the resin, and is preferably 3 seconds to 3 minutes, more preferably 5 to 60 seconds, and further preferably 10 to 30 seconds.

[0097] After the heating treatment, it is preferable to perform a heat-retention treatment at a temperature lower than the melting point of the P3HB-based resin. As the heat-retention temperature, 35 to 70°C is preferable, and 40 to 60°C is more preferable. By heat-retaining at this temperature, the crystallization of the P3HB-based resin after the heating treatment is accelerated, and the productivity of the laminate is improved. In addition, it is possible to reduce blocking caused by the adhesion of the base material layer to the resin layer or the base material layer to the coating layer when the laminate is continuously manufactured and wound into a roll shape.

[0098] The heat-retention treatment can be performed using the same heating method as the heating treatment described above, and examples thereof include hot air heating, infrared heating, microwave heating, roll heating, hot plate heating, and the like, which can be used alone or in combination of two or more. In particular, from the viewpoint of being able to make the surface properties of the resin layer uniform, it is preferable to use a roll adjusted to a specific temperature, and to bring the resin-coated surface into contact with the roll. Further preferably, a roll is provided on the base material layer side, and the laminate is sandwiched from both sides.

[0099] Note that the heat-retention temperature in the heat-retention treatment is not the temperature actually exhibited by the laminate, but is the set temperature of the drying furnace, roll, or the like used in the heat-retention treatment.

[0100] The treatment time in the heat retention treatment can be appropriately set in consideration of the effect of the heat retention treatment, and is preferably 3 seconds to 1 minute, more preferably 5 to 30 seconds, and further preferably 10 to 20 seconds, for example.

[0101] In the case where the substrate is paper, the adjustment of the amount of moisture contained in the paper substrate can be performed by water coating of the paper substrate, so-called humidity adjustment treatment, after the heat treatment and optional heat retention treatment, as needed. Alternatively, the planarization treatment using a mechanical calender, a soft calender, or the like can be performed in combination.

[0102] The method of water coating the paper substrate is not particularly limited as long as it is a method capable of uniformly coating the paper substrate. Known methods such as spray coating, scattering, slit coating, air-knife coating, roll coating, bar coating, doctor blade coating, screen printing, gravure printing, and the like can be used alone or in combination. Among them, from the viewpoint of being able to uniformly coat with a small amount of water without unevenness, spray coating is preferred. The spray coating of water can be performed using, for example, a commercially available liquid coating device characterized by non-contact coating.

[0103] Note that, in a range not impairing the object, the water can contain a humectant such as glycerin or propylene glycol, various flavors, preservatives, and the like as additives.

[0104] The series of processes involved in the formation of the coating layer described above can be performed on a substrate that has been cut into a sheet shape in advance, or a substrate that has been prepared in the form of a roll in which a roll-shaped substrate is wound, can be continuously fed while being transported using a conveyance device for a sheet, a film, paper, or the like, and can be continuously performed.

[0105] (Use)

[0106] The laminate obtained by the present embodiment can be manufactured into various molded bodies by secondary processing. As such molded bodies, for example, a tube, a sheet, a rod, a packaging material (for example, a bag), a container (for example, a bottle container), a member, and the like can be exemplified. In particular, the molded bodies described above can be preferably used as a shopping bag, various bags, a packaging material for food / snacks, a cup, a tray, a carton, and the like (in other words, for various fields such as food, cosmetics, electronics, medical care, pharmaceuticals, and the like). In addition, the molded bodies described above have a resin layer having high adhesion to the substrate and good heat resistance formed on one side of the paper substrate, and thus can be particularly preferably used as a container for containing a warm content, such as a container for containing a liquid, in particular, a cup for a beverage food such as instant noodles, instant soup, coffee, and the like, a tray for a vegetarian dish, a bento, a microwave oven food, and the like.

[0107] The above-mentioned two processes can be performed using any method known in the art, such as various bag-making machines, filling and packaging machines, and the like. In addition, the processes can also be performed using a paper tray press molding machine, a paper cup molding machine, a blanking machine, a box-making machine, and the like. In these processing machines, the known techniques can be used when the laminate is bonded, such as a heat sealing method, a pulse sealing method, an ultrasonic sealing method, a high frequency sealing method, a hot air sealing method, a flame sealing method, and the like. The heat sealing can be performed between the base material layer and the resin layer, or between the resin layers.

[0108] The above-mentioned molded body can also be complexed with another molded body (for example, a fiber, a filament, a cord, a fabric, a woven fabric, a nonwoven fabric, paper, a film, a sheet, a tube, a plate, a rod, a container, a bag, a member, a foam, and the like) composed of a material different from the molded body in order to improve the physical properties thereof. These materials are also preferably biodegradable.

[0109] Preferred modes in the present disclosure are listed in each of the following items, but the present application is not limited to the following items.

[0110] [Item 1]

[0111] A method for manufacturing a laminate having a base material layer and a resin layer formed on at least one surface of the base material layer, the resin layer containing a poly(3-hydroxybutyrate)-based resin, and the resin layer having a weight per unit area (dry weight) of 15 to 50 g / m 2 ,

[0112] The above-mentioned manufacturing method includes at least sequentially performing the following process (i) and process (ii):

[0113] Process (i), forming a coating film (a) by applying an aqueous dispersion (HB-A) to a surface of the base material layer, and heating the coating film (a) to form a coating layer (A) having a weight per unit area (dry weight) of 0.5 to 10 g / m 2 of the aqueous dispersion (HB-A) contains a poly(3-hydroxybutyrate)-based resin (al) and a dispersant (a2) containing a water-soluble polymer, and the content of the dispersant (a2) containing a water-soluble polymer is 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (al);

[0114] Process (ii) forming a coating film (b) by applying the aqueous dispersion (HB-B) to the surface of the coating (A) on the aforementioned coating (A) side and forming a coating (B) by heating the coating film (b), the aqueous dispersion (HB-B) containing a poly(3-hydroxybutyrate)-based resin (b1) and a dispersant (b2) containing a water-soluble polymer, and the content of the dispersant (b2) containing a water-soluble polymer being 0 to 0.5 parts by weight with respect to 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (b1).

[0115] [Item 2]

[0116] The production method according to item 1, wherein the weight average molecular weight of at least one of the poly(3-hydroxybutyrate)-based resins (a1) and (b1) is 100,000 to 700,000.

[0117] [Item 3]

[0118] The production method according to item 1 or 2, wherein at least one of the poly(3-hydroxybutyrate)-based resins (a1) and (b1) has at least one peak top temperature (Tma) in the range of 100 to 150°C and at least one peak top temperature (Tmb) in the range of 150 to 170°C in a crystalline melting curve based on differential scanning calorimetry, and the temperature difference between Tma and Tmb is 10°C or more.

[0119] [Item 4]

[0120] The production method according to any one of items 1 to 3, wherein at least one of the poly(3-hydroxybutyrate)-based resins (a1) and (b1) contains at least one poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0121] [Item 5]

[0122] The production method according to any one of items 1 to 4, wherein the solid content concentration of the poly(3-hydroxybutyrate)-based resin (a1) or (b1) in at least one of the aqueous dispersions (HB-A) and (HB-B) is 25 to 65% by weight.

[0123] [Item 6]

[0124] The production method according to any one of items 1 to 5, further comprising the following process (iii) between the process (i) and the process (ii).

[0125] Process (iii):

[0126] Process (iii) forming a coating film (c) by applying an aqueous dispersion liquid (HB-C) containing a poly(3-hydroxybutyrate)-based resin (c1) to the surface of the coating layer (A) side, and heating the coating film (c) to form a coating layer (C).

[0127] [Item 7]

[0128] The production method according to Item 6, wherein the weight average molecular weight of at least one of the poly(3-hydroxybutyrate)-based resins (a1), (b1), and (c1) is 100,000 to 700,000.

[0129] [Item 8]

[0130] The production method according to Item 6 or 7, wherein at least one of the poly(3-hydroxybutyrate)-based resins (a1), (b1), and (c1) has at least one peak top temperature (Tma) in the range of 100 to 150°C and at least one peak top temperature (Tmb) in the range of 150 to 170°C in a crystalline melting curve based on differential scanning calorimetry, and the temperature difference between Tma and Tmb is 10°C or more.

[0131] [Item 9]

[0132] The production method according to any one of Items 6 to 8, wherein at least one of the poly(3-hydroxybutyrate)-based resins (a1), (b1), and (c1) contains at least one poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0133] [Item 10]

[0134] The production method according to any one of Items 6 to 9, wherein the solid content concentration of the poly(3-hydroxybutyrate)-based resin (a1), (b1), or (c1) in at least one of the aqueous dispersion liquids (HB-A), (HB-B), and (HB-C) is 25 to 65% by weight.

[0135] [Item 11]

[0136] The production method according to any one of Items 1 to 10, wherein the substrate layer has biodegradability.

[0137] [Item 12]

[0138] The production method according to Item 11, wherein the substrate layer is paper.

[0139] [Item 13]

[0140] A laminate having a substrate layer, and a resin layer formed on at least one surface of the substrate layer, the resin layer containing a poly(3-hydroxybutyrate)-based resin, and having a weight per unit area (dry weight) of 15 to 50 g / m 2 ,

[0141] The laminate contains, in order, a substrate layer, a coating layer (A), and a coating layer (B),

[0142] The coating layer (A) contains a poly(3-hydroxybutyrate)-based resin (al) and a dispersant (a2) containing a water-soluble polymer, and has a weight per unit area (dry weight) of 0.5 to 10 g / m 2 , and the content of the dispersant (a2) containing a water-soluble polymer is 0.1 to 2.0 parts by weight per 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (al),

[0143] The coating layer (B) contains a poly(3-hydroxybutyrate)-based resin (bl) and a dispersant (b2) containing a water-soluble polymer, and the content of the dispersant (b2) containing a water-soluble polymer is 0 to 0.5 parts by weight per 100 parts by weight of the poly(3-hydroxybutyrate)-based resin (bl).

[0144] [Item 14]

[0145] The laminate according to item 13, further containing a coating layer (C) containing a poly(3-hydroxybutyrate)-based resin (cl) between the coating layer (A) and the coating layer (B).

[0146] [Item 15]

[0147] A molded body containing the laminate according to item 13 or 14.

[0148] [Item 16]

[0149] The molded body according to item 15, wherein the molded body is a container for a beverage food.

[0150] Examples

[0151] Hereinafter, specific description will be made based on examples, but the technical scope of the present application is not limited by these examples.

[0152] (Method for measuring weight per unit area of resin)

[0153] The laminate obtained in each example and comparative example was cut into 10 cm x 10 cm, and the weight was measured, and the weight of the substrate was subtracted from the weight value and multiplied by 100, and the obtained value was taken as the value of the weight per unit area of the resin (dry weight per unit area of the resin layer or the coating layer).

[0154] (Adhesion of the substrate (paper) to the resin layer)

[0155] For the laminates obtained in each of the examples and comparative examples, the adhesion of the substrate layer to the resin layer was evaluated by the following criteria. A crosscut of 30 mm in length was formed on the resin layer with a cutter, Cellophane tape (registered trademark, type: NICHIBAN, CT-18) was attached to the cut surface and peeled by hand, and the peeling strength of the resin layer from the substrate layer was evaluated, whereby crosscut evaluation within the criteria was performed.

[0156] < Evaluation >

[0157] ◎: The resin layer was not peeled from the substrate after the heat treatment, and the fibers of the paper were attached to the resin layer when the resin layer was peeled in the crosscut evaluation

[0158] O: The resin layer was not peeled from the substrate after the heat treatment, and the fibers of the paper were not attached to the resin layer although there was resistance when the resin layer was peeled in the crosscut evaluation

[0159] X: The resin layer was peeled from the substrate after the heat treatment, and a crack was generated on the entire surface of the resin layer

[0160] (Method for producing aqueous dispersion of P3HB3HH)

[0161] An aqueous dispersion containing 50% by weight of P3HB3HH having a content ratio of 3-hydroxyhexanoate units of 11 mol% (weight average molecular weight 550,000) and a peak top temperature Tma of a melting point peak existing in the range of 100 to 150°C of 110°C and a peak top temperature Tmb of a melting point peak existing in the range of 150 to 170°C of 160°C was obtained according to the method described in International Publication No. 2015 / 146195.

[0162] For Tma and Tmb, the obtained aqueous dispersion was dried and solidified with a hot air drier at 60°C, 2 to 5 mg of the obtained dried and solidified product was filled into an aluminum pan, and the dried and solidified product was melted by raising the temperature from 20°C to 190°C at a rate of 10°C / min under a nitrogen stream using a differential scanning calorimeter, and measurement was performed.

[0163] (Method for producing aqueous dispersion)

[0164] HB-A1: 0.3 parts by weight of methylcellulose (METOLOSE SM-400, manufactured by Shin-Etsu Chemical Co., Ltd.) as a water-soluble polymer dispersant was mixed with water in a manner of 100 parts by weight of the P3HB3HH resin contained in the aqueous dispersion liquid to 0.3 parts by weight, and stirring was performed to obtain an aqueous dispersion liquid containing P3HB3HH and the dispersant at a total solid content concentration of 40% by weight (P3HB3HH: 39.9% by weight).

[0165] HB-A2: 1.0 parts by weight of methylcellulose was mixed with water in a manner of 100 parts by weight of the P3HB3HH resin to 1.0 parts by weight, and stirring was performed to obtain an aqueous dispersion liquid containing P3HB3HH and the dispersant at a total solid content concentration of 40% by weight (P3HB3HH: 39.6% by weight), except for the above, in the same manner as HB-A1.

[0166] HB-A3, HB-C1: 1.5 parts by weight of methylcellulose was mixed with water in a manner of 100 parts by weight of the P3HB3HH resin to 1.5 parts by weight, and stirring was performed to obtain an aqueous dispersion liquid containing P3HB3HH and the dispersant at a total solid content concentration of 40% by weight (P3HB3HH: 39.4% by weight), except for the above, in the same manner as HB-A1.

[0167] HB-B1: 40% by weight of the P3HB3HH aqueous dispersion liquid described above was added with water to obtain an aqueous dispersion liquid containing P3HB3HH at a solid content concentration of 40% by weight.

[0168] [Example 1]

[0169] An aqueous dispersion liquid HB-A1 was applied to one side of a cup base paper having a weight per unit area of 200 g / m2using a bar coater so that the weight per unit area of the dried resin was 3 g / m2, and then heated in a hot air drying oven set at 180°C for 1 minute to form a coating layer (A). Subsequently, an aqueous dispersion liquid HB-B1 was applied to the coating layer (A) using a bar coater so that the weight per unit area of the dried resin was 15 g / m2, and then heated in a hot air drying oven set at 180°C for 2 minutes to form a coating layer (B), and the formation of the resin layer was completed. 2 2 2

[0170] The adhesion of the base material (paper) to the resin layer of the obtained laminate was evaluated. The results are shown in Table 1.

[0171] [Examples 2 to 4]

[0172] ​​​The kind of the water-based dispersion used for forming the coating layers (A) and (B) and the resin unit area weight after drying were set as described in Examples 2 to 4 in Table 1, and otherwise, the same operation as in Example 1 was performed to obtain a laminate, and the adhesion of the substrate (paper) to the resin layer was evaluated for the obtained laminate. The results are shown in Table 1.

[0173] [Example 5]

[0174] The water-based dispersion HB-A3 was applied to one side of the cup base paper having a unit area weight of 200 g / m2using a bar coater so that the resin unit area weight after drying was 1 g / m2, and then, heated for 30 seconds in a hot air drying oven set at 180°C to form the coating layer (A). Subsequently, the water-based dispersion HB-C1 was applied to the coating layer (A) using a bar coater so that the resin unit area weight after drying was 10 g / m2, and then, heated for 1 minute in a hot air drying oven set at 180°C to form the coating layer (C). Further, the water-based dispersion HB-B2 was applied to the coating layer (C) using a bar coater so that the resin unit area weight after drying was 25 g / m2, and then, heated for 2 minutes in a hot air drying oven set at 180°C to complete the formation of the resin layer. 2 2 The water-based dispersion HB-A3 was applied to one side of the cup base paper having a unit area weight of 200 g / m2using a bar coater so that the resin unit area weight after drying was 1 g / m2, and then, heated for 30 seconds in a hot air drying oven set at 180°C to form the coating layer (A). Subsequently, the water-based dispersion HB-C1 was applied to the coating layer (A) using a bar coater so that the resin unit area weight after drying was 10 g / m2, and then, heated for 1 minute in a hot air drying oven set at 180°C to form the coating layer (C). Further, the water-based dispersion HB-B2 was applied to the coating layer (C) using a bar coater so that the resin unit area weight after drying was 25 g / m2, and then, heated for 2 minutes in a hot air drying oven set at 180°C to complete the formation of the resin layer. 2 2 The water-based dispersion HB-A3 was applied to one side of the cup base paper having a unit area weight of 200 g / m2using a bar coater so that the resin unit area weight after drying was 1 g / m2, and then, heated for 30 seconds in a hot air drying oven set at 180°C to form the coating layer (A). Subsequently, the water-based dispersion HB-C1 was applied to the coating layer (A) using a bar coater so that the resin unit area weight after drying was 10 g / m2, and then, heated for 1 minute in a hot air drying oven set at 180°C to form the coating layer (C). Further, the water-based dispersion HB-B2 was applied to the coating layer (C) using a bar coater so that the resin unit area weight after drying was 25 g / m2, and then, heated for 2 minutes in a hot air drying oven set at 180°C to complete the formation of the resin layer.

[0175] The adhesion of the substrate (paper) to the resin layer was evaluated for the obtained laminate. The results are shown in Table 1.

[0176] [Comparative Example 1]

[0177] The water-based dispersion HB-B1 was applied to one side of the cup base paper having a unit area weight of 200 g / m2using a bar coater so that the resin unit area weight after drying was 15 g / m2, and then, heated for 2 minutes in a hot air drying oven set at 180°C to form the resin layer. The adhesion of the substrate (paper) to the resin layer was evaluated for the obtained laminate. The results are shown in Table 1. 2 2 The water-based dispersion HB-B1 was applied to one side of the cup base paper having a unit area weight of 200 g / m2using a bar coater so that the resin unit area weight after drying was 15 g / m2, and then, heated for 2 minutes in a hot air drying oven set at 180°C to form the resin layer. The adhesion of the substrate (paper) to the resin layer was evaluated for the obtained laminate. The results are shown in Table 1.

[0178] [Comparative Example 2]

[0179] The water-based dispersion HB-B2 was used, and the resin unit area weight after drying was made to be 25 g / m2, and otherwise, the same operation as in Comparative Example 1 was performed to obtain a laminate, and the adhesion of the substrate (paper) to the resin layer was evaluated. The results are shown in Table 1. 2

[0180]

[0181] [Results]

[0182] ​​​​As shown in Table 1, in Examples 1 to 5 in which the coating layer (A) was provided in advance on the paper substrate at a given amount of the unit area weight, peeling of the resin layer after the heat treatment was suppressed, and a laminate having a resin layer with a high unit area weight could be produced.

[0183] On the other hand, in Comparative Examples 1 and 2 in which a resin layer with a high unit area weight was formed in one step, peeling of the resin layer from the substrate layer occurred, and in addition, cracks were generated on the entire surface of the resin layer. The affinity of the poly(3-hydroxybutyrate) resin to other materials is low, and it can be presumed that, in the case of coating at a high unit area weight directly without forming a low unit area weight coating layer (A) on the substrate layer in advance as in the Examples, the coagulation and fusion of resin particles to each other would be preferentially performed in a state in which the resin does not wet and spread on the substrate at the time of heat treatment, and peeling of the resin layer would occur.

Claims

1. A method for producing a laminate having a substrate layer, and a resin layer formed on at least one side of the substrate layer, the resin layer containing a poly(3-hydroxybutyrate)-based resin, and the resin layer having a weight per unit area of 15 to 50 g / m2. 2 , The production method includes at least sequentially performing the following process (i) and process (ii): Process (i) of coating an aqueous dispersion HB-A on the surface of the substrate layer to form a coated film a, and heating the coated film a to form a coating layer A having an average weight per unit area of 0.5 to 10 g / m 2 Process (i) of coating an aqueous dispersion HB-A on the surface of the substrate layer to form a coated film a, and heating the coated film a to form a coating layer A having an average weight per unit area of 0.5 to 10 g / m Process (i) of coating an aqueous dispersion HB-A on the surface of the substrate layer to form a coated film a, and heating the coated film a to form a coating layer A having an average weight per unit area of 0.5 to 10 g / m Process (i) of coating an aqueous dispersion HB-A on the surface of the substrate layer to form a coated film a, and heating the coated film a to form a coating layer A having an average weight per unit area of 0.5 to 10 g / m Process (i) of coating an aqueous dispersion HB-A on the surface of the substrate layer to form a coated film a, and heating the coated film a to form a coating layer A having an average weight per unit area of 0.5 to 10 g / m Process (i) of coating an aqueous dispersion HB-A on the surface of the substrate layer to form a coated film a, and heating the coated film a to form a coating layer A having an average weight per unit area Process (ii), forming a coating film b by applying an aqueous dispersion HB-B to the surface on the side of the coating A, and forming a coating B by heating the coating film b, the aqueous dispersion HB-B containing a poly(3-hydroxybutyrate)-based resin b1 and a dispersant b2 containing a water-soluble polymer, and the content of the dispersant b2 containing a water-soluble polymer being 0 to 0.5 parts by weight with respect to 100 parts by weight of the poly(3-hydroxybutyrate)-based resin b1, The average weight per unit area is a dry weight.

2. The production method according to claim 1, wherein The weight average molecular weight of at least one of the poly(3-hydroxybutyrate)-based resins a1 and b1 is 100,000 to 700,000.

3. The production method according to claim 1 or 2, wherein At least one of the poly(3-hydroxybutyrate)-based resins a1 and b1 has at least one peak top temperature Tma in the range of 100 to 150°C and at least one peak top temperature Tmb in the range of 150 to 170°C in a crystalline melting curve based on differential scanning calorimetry, and the temperature difference between Tma and Tmb is 10°C or more.

4. The production method according to claim 1 or 2, wherein At least one of the poly(3-hydroxybutyrate)-based resins a1 and b1 contains at least one poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

5. The production method according to claim 1 or 2, wherein In at least one of the aqueous dispersions HB-A and HB-B, the solid content concentration of the poly(3-hydroxybutyrate)-based resin a1 or b1 is 25 to 65% by weight.

6. The production method according to claim 1, further comprising the following process (iii) between the process (i) and process (ii): Process (iii), forming a coating film c by applying an aqueous dispersion HB-C containing a poly(3-hydroxybutyrate)-based resin c1 to the surface on the side of the coating A, and forming a coating C by heating the coating film c.

7. The production method according to claim 6, wherein The weight average molecular weight of at least one of the poly(3-hydroxybutyrate)-based resins a1, b1 and c1 is 100,000 to 700,000.

8. The production method according to claim 6 or 7, wherein At least one of the poly(3-hydroxybutyrate)-based resins a1, b1 and c1 has at least one peak top temperature Tma in the range of 100 to 150°C and at least one peak top temperature Tmb in the range of 150 to 170°C in a crystalline melting curve based on differential scanning calorimetry, and the temperature difference between Tma and Tmb is 10°C or more.

9. The production method according to claim 6 or 7, wherein At least one of the poly(3-hydroxybutyrate)-based resins a1, b1 and c1 contains at least one poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

10. The production method according to claim 6 or 7, wherein In at least one of the aqueous dispersions HB-A, HB-B, and HB-C, the solid content concentration of the poly(3-hydroxybutyrate)-based resin a1, b1, or c1 is 25 to 65% by weight.

11. The production method according to claim 1 or 6, wherein The substrate layer has biodegradability.

12. The production method according to claim 11, wherein The substrate layer is paper.

13. A laminate having a substrate layer, and a resin layer formed on at least one side of the substrate layer, the resin layer comprising a poly(3-hydroxybutyrate)-based resin, and having a weight per unit area of 15 to 50 g / m2. 2 , The laminate successively comprises a substrate layer, a coating layer A, and a coating layer B, The coating layer A contains a poly(3-hydroxybutyrate)-based resin a1 and a dispersant a2 containing a water-soluble high molecule, and the weight per unit area of the coating layer A is 0.5 to 10 g / m 2 The content of the dispersant a2 containing a water-soluble high molecule is 0.1 to 2.0 parts by weight, relative to 100 parts by weight of the poly(3-hydroxybutyrate)-based resin a1. The coating layer B comprises a poly(3-hydroxybutyrate)-based resin b1 and a dispersant b2 containing a water-soluble high molecule, and the content of the dispersant b2 containing a water-soluble high molecule is 0 to 0.5 parts by weight with respect to 100 parts by weight of the poly(3-hydroxybutyrate)-based resin b1, The average weight per unit area is a dry weight.

14. The laminate according to claim 13, further comprising a coating layer C containing a poly(3-hydroxybutyrate)-based resin c1 between the coating layer A and the coating layer B.

15. A molded body comprising the laminate according to claim 13 or 14.

16. The molded body according to claim 15, which is a container for a beverage food.

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