Method for manufacturing laminate and method for manufacturing molded article

Abstract

Provided is a method for producing a laminate having a substrate layer and a coating layer laminated on at least one surface of the substrate layer. An aqueous coating liquid of a poly (3-hydroxyalkanoate)-based resin composition is applied to a substrate to form a coating film, and the coating film is heated until the surface temperature of the coating film reaches 170 DEG C or higher to form a coating layer. In a crystal melting curve based on differential scanning calorimetry, the coating has a peak top temperature (Tmb) in the range of 155-175 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to a manufacturing method of a laminate having a resin layer containing a poly(3-hydroxyalkanoate)-based resin, and a manufacturing method of a molded body containing the laminate. 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 plastics are known, among which poly(3-hydroxyalkanoate)-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, so they are attracting attention as raw materials to solve the above problems.

[0004] A laminate in which a layer containing a poly(3-hydroxyalkanoate)-based resin as a main component is laminated on a paper base material having biodegradability is a material in which both the resin and the base material have excellent biodegradability, and is promising from the viewpoint of environmental protection.

[0005] In Patent Literature 1, in a laminate containing a base material layer and a coating layer containing a poly(3-hydroxybutyrate)-based resin, in order to improve heat sealability at the time of molding processing, a specific melting property is imparted to the coating layer. It is also described that, at the time of this production, after an aqueous coating solution containing a poly(3-hydroxybutyrate)-based resin is applied to a paper base material, heating is performed in the range of 130 to 170°C to form a coating layer.

[0006] In Patent Literature 2, by applying an aqueous coating solution containing a poly(3-hydroxybutyrate)-based resin to a paper base material, heating to a melting point or higher of the resin is performed to form a resin layer, and further a cooling medium is blown to the surface of the paper base material layer, whereby adhesion of the laminates to each other is suppressed.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT LITERATURE

[0009] Patent Literature 1: International Publication No. 2022 / 059592

[0010] Patent Literature 2: Japanese Patent Application Publication No. 2022-185708 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] According to the production method described in Patent Document 1, heat sealability at the time of molding of the laminate can be improved. However, when the laminate is wound in a roll shape, the laminate sometimes adheres to each other (i.e., the paper base material and the resin layer after contact adhere), resulting in a failure at the time of unwinding from the roll.

[0013] On the other hand, according to the production method described in Patent Document 2, although such adhesion can be suppressed, the water resistance or oil resistance in the obtained laminate is sometimes insufficient. Therefore, there is a problem that the laminate is difficult to use as a packaging material for packaging an article containing water or oil, for example.

[0014] In view of the above circumstances, an object of the present application is to provide a production method of a laminate including a base material layer and a resin layer, which is produced by applying an aqueous coating liquid containing a poly(3-hydroxyalkanoate)-based resin to the base material layer, the method being capable of suppressing adhesion of the laminate to each other and imparting good water resistance and oil resistance to the laminate.

[0015] Method for solving the problem

[0016] The present inventors have found that, by applying an aqueous coating liquid containing a poly(3-hydroxyalkanoate)-based resin to a base material layer, then heating until the surface temperature of the coating film reaches a specific temperature, while controlling the coating layer to exhibit a specific melting behavior, the above problem can be solved, thereby completing the present application.

[0017] That is, the present application relates to a production method of a laminate having a base material layer and a coating layer laminated to at least one surface of the base material layer, the method including:

[0018] a step of applying an aqueous coating liquid of a poly(3-hydroxyalkanoate)-based resin composition to a base material to form a coating film; and

[0019] a step of heating the coating film until the surface temperature of the coating film reaches 170°C or higher to form the coating layer,

[0020] the coating layer has a peak top temperature (Tmb) in the range of 155°C to 175°C in a crystalline melting curve based on differential scanning calorimetry.

[0021] In addition, the present application also relates to a production method of a molded body, the method including:

[0022] a step of producing a laminate by the above production method; and

[0023] a step of heat-fusible processing at least a part of the coating layer.

[0024] Effects of the Invention

[0025] According to the present application, it is possible to provide a production method of producing a laminate including a substrate layer and a resin layer by applying an aqueous coating liquid including a poly(3-hydroxyalkanoate)-based resin to the substrate layer, which can suppress adhesion of the laminates to each other and can impart good water resistance and oil resistance to the laminate.

[0026] The laminate produced by the present application can achieve coating adhesion by heat sealing, and thus can exhibit good adhesion strength.

[0027] In addition, according to the present application, the process of spraying water as a cooling medium to the surface of the substrate layer described in Patent Document 2 can be omitted or simplified. Thus, it is not necessary to adjust the water content of the substrate after the spraying (drying) of water, and generation of wrinkles, poor winding, and the like due to the spraying and drying of water can be avoided. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present application will be described, but the present application is not limited to the following embodiments.

[0029] The production method of one embodiment of the present disclosure is a method of producing a laminate. The laminate includes at least a substrate, and a coating layer formed on one side or both sides of the substrate. According to a preferred mode, the laminate as a whole can exhibit biodegradability.

[0030] The coating layer described above can be laminated directly to the substrate, or can be laminated via another layer, and is preferably laminated directly.

[0031] (Substrate)

[0032] The material constituting the substrate described above is not particularly limited, and is desirably biodegradable. For example, paper, cellophane, cellulose ester, polyvinyl alcohol, polyamino acid, polyglycolic acid, pullulan, or a material in which an inorganic substance such as aluminum or silicon dioxide is vapor-deposited on these substrates, and the like can be given. Among them, from the viewpoint of excellent heat resistance and low cost, paper is preferred.

[0033] Paper is mainly composed of a sheet made of paper pulp. The paper substrate can be obtained by papermaking a papermaking raw material containing a filler, various kinds of additives, and the like in the paper pulp.

[0034] The kind of paper that can be used is not particularly limited, and paper cup wax paper, kraft paper, full-sized paper, coated paper, tissue paper, glassine paper, paperboard, and the like can be given.

[0035] The pulp is not particularly limited and examples thereof include chemical pulp such as bleached kraft pulp (LBKP), bleached kraft pulp (NBKP), unbleached kraft pulp (LUKP), unbleached kraft pulp (NUKP), sulfite pulp, etc.; mechanical pulp such as stone ground pulp, thermomechanical pulp, etc.; wood fibers such as deinked pulp, old paper pulp, etc.; non-wood fibers obtained from esparto, bamboo, hemp, etc.; and the like. These can be appropriately combined and used.

[0036] Among them, chemical pulp of wood fibers, mechanical pulp, and more preferably chemical pulp are preferably used from the viewpoint of not easily mixing foreign matters in the paper, not easily causing discoloration over time when recycled as a raw material of waste paper, good surface feeling at the time of printing due to high whiteness, high value as a packaging material, and the like. Specifically, the blending amount of chemical pulp such as LBKP, NBKP, etc. in the pulp is preferably 80% or more, and the blending amount of chemical pulp is particularly preferably 100%.

[0037] The filler is not particularly limited and examples thereof include inorganic fillers such as talc, kaolin, calcined kaolin, clay, heavy calcium carbonate, light calcium carbonate, white carbon, zeolite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silicon dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, barium sulfate, calcium sulfate, etc.; organic fillers such as urea-formaldehyde resin, polystyrene resin, phenolic resin, fine hollow particles, etc.; and the like. Note that the filler is not necessarily required and can not be used.

[0038] The various additives are not particularly limited and examples thereof include sizing agents such as rosin, alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), etc.; dry paper strength enhancers such as polyacrylamide-based polymers, polyvinyl alcohol-based polymers, cationized starch, various modified starches, urea-formaldehyde resin, melamine-formaldehyde resin, etc.; wet paper strength enhancers, yield enhancers (Sizings) (Sizings), filter aids, coagulants, aluminum sulfate, bulking agents (Bulking Agents), dyes, fluorescent whitening agents, pH adjustors, antifoaming agents, ultraviolet light preventers, anti-fading agents, pitch control agents (Pitch Control Agents), slime control agents (Slime Control Agents), etc. These can be appropriately selected and used as needed.

[0039] ​​The surface of paper can be treated with various chemical agents. There are no particular limitations on the chemical agents used; examples include oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, polyacrylamide, polyvinyl alcohol, surface sizing agents, water-resistant agents, water-retaining agents, tackifiers, and lubricants. Only one chemical agent can be used, or two or more can be combined. Furthermore, these chemical agents can be used in combination with pigments.

[0040] As a pigment, there are no particular limitations; examples include kaolin, clay, special kaolin, and layered clay. Inorganic pigments include heavy calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white; organic pigments include dense, hollow, or core-shell types. One type can be used as a pigment, or two or more types can be used in combination.

[0041] The weight per unit area of ​​the substrate, especially the paper substrate, can be appropriately selected according to the desired quality and the intended use of the laminate, and is preferably 40 g / m². 2 Above and 400g / m 2 The following is more preferably 50g / m 2 Above and 350g / m 2 The following applies to the use of the laminate in packaging materials such as wrapping paper, paper bags, lids, liners, and flexible packaging materials, as well as outdoor posters, where 40 g / m² is further preferred. 2 Above and 150g / m 2 The following should be noted: Flexible packaging materials refer to packaging materials, especially those using 40g / m³. 2 ~100g / m 2 This is a lightweight, thin, and flexible packaging material. Furthermore, when using the laminated material for paper cups, cartons, plates, dishes, lids, and other paper containers, a weight of 150 g / m² is even more preferable. 2 Above and 400g / m 2 the following.

[0042] The density of the substrate, especially paper substrate, can be appropriately selected according to the desired quality, handling, etc., and is usually preferably 0.5 g / cm³. 3 Above and 1.0 g / cm 3 the following.

[0043] There are no particular limitations on the manufacturing method of the substrate. Well-known papermaking machines such as two-wire machines, cylinder papermaking machines, short-wire papermaking machines, gap-form papermaking machines, and hybrid-form papermaking machines (on-top former type) can be appropriately selected. The pH during papermaking can be any of the following: acidic (acidic papermaking), near-neutral (near-neutral papermaking), neutral (neutral papermaking), or alkaline (alkaline papermaking). Alternatively, after papermaking in the acidic range, alkaline chemicals can be applied to the surface of the paper layers. Furthermore, the paper substrate can consist of one layer or multiple layers (two or more).

[0044] When treating the surface of paper substrates with chemical agents, there are no particular limitations on the surface treatment method; a metering rod sizing machine can be used. Pond type glue applicator Commonly known coating equipment includes roller coating machines, spray coating machines, scraper coating machines, curtain coating machines, etc.

[0045] (coating)

[0046] The coating formed on at least one side of the substrate contains at least a poly(3-hydroxyalkanoate) resin (hereinafter also referred to as P3HA). P3HA may be used alone or in combination of two or more. Furthermore, the resin component in the coating may be only P3HA, or may further contain other resins. Biodegradable resins described later may be used as these other resins.

[0047] The aforementioned poly(3-hydroxyalkanoate) resins refer to a general term for polymers that contain at least 3-hydroxyalkanoic acid as a monomer unit. There is no particular limitation on the 3-hydroxyalkanoic acid constituting P3HA; examples include 3-hydroxybutyric acid, 3-hydroxypropionic acid, 3-hydroxyvalerate, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, and 3-hydroxyoctanoic acid. P3HA can be a homopolymer or a copolymer containing two or more monomer units.

[0048] In addition to at least one of the 3-hydroxyalkanoic acids mentioned above, P3HA can also be a copolymer containing other hydroxyalkanoic acids (e.g., 4-hydroxybutyric acid and other 4-hydroxyalkanoic acids) as monomer units.

[0049] The coating preferably contains 50% by weight or more of P3HA, more preferably 70% by weight or more, even more preferably 80% by weight or more, and still more preferably 90% by weight or more. By using P3HA as the main component, the coating exhibits good biodegradability.

[0050] P3HA is preferably a poly(3-hydroxybutyrate) resin (hereinafter also referred to as P3HB).

[0051] P3HB refers to homopolymers containing only 3-hydroxybutyrate units and / or copolymers containing 3-hydroxybutyrate units and other hydroxyalkanoate units. From the viewpoint of seawater decomposability, copolymers containing 3-hydroxybutyrate units and other hydroxyalkanoate units are preferred.

[0052] The copolymerization form of the above copolymers is not particularly limited and can be random copolymerization, alternating copolymerization, block copolymerization, graft copolymerization, etc. Copolymers produced by microorganisms are usually random copolymers.

[0053] There are no particular limitations on the hydroxyalkanoic acid that forms the other hydroxyalkanoic acid ester units mentioned above, and examples include: 4-hydroxybutyric acid, 3-hydroxypropionic acid, 3-hydroxyvalerate, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, etc.

[0054] Specific examples of P3HB include: poly(3-hydroxybutyrate) (abbreviated as PHB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviated as PHBH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviated as P3HB3HV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviated as P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (abbreviated as P3HB3HO), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate) (abbreviated as P3HB3HOD), poly(3-hydroxybutyrate-co-3-hydroxydecanoate) (abbreviated as P3HB3HD), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (abbreviated as P3HB3HV3HH). From the perspective of ease of industrial production, PHB, PHBH, P3HB3HV, and P3HB4HB are preferred. P3HB can be used alone or in combination with two or more.

[0055] The coating preferably contains 50% by weight or more of P3HB, more preferably 70% by weight or more, even more preferably 80% by weight or more, and still more preferably 90% by weight or more. By using P3HB as the main component, the coating exhibits good biodegradability.

[0056] In P3HB, PHBH can change the melting point and crystallinity by altering the composition ratio of repeating units. As a result, it can adjust physical properties such as Young's modulus and heat resistance, and can impart physical properties between polypropylene and polyethylene. Furthermore, it is easy to industrially produce and is a useful plastic in terms of physical properties. Considering the above points, PHBH is particularly preferred.

[0057] To satisfy the melting characteristics described later, the coating preferably contains poly(3-hydroxybutyrate) (A) as P3HA. By including poly(3-hydroxybutyrate) (A), the coating has a peak temperature (Tmb) in the range of 155°C to 175°C as described later, and the curing of the resin component after melting based on the heating process of the coating described later proceeds rapidly, thus suppressing the adhesion of the laminate.

[0058] Poly(3-hydroxybutyrate) (A) refers to a homopolymer consisting solely of 3-hydroxybutyrate units, or a polymer containing trace amounts of hydroxyalkanoate units other than 3-hydroxybutyrate units. Specifically, in all the monomers constituting poly(3-hydroxybutyrate) (A), the proportion of 3-hydroxybutyrate units is preferably greater than 99 mol% and less than 100 mol%.

[0059] The hydroxyalkanoate units that can be included in poly(3-hydroxybutyrate) (A) other than 3-hydroxybutyrate units are not particularly limited, as long as they can copolymerize with 3-hydroxybutyrate units. Examples include, for instance, 3-hydroxyalkanoate units other than 3-hydroxybutyrate units, and hydroxyalkanoate units other than 3-hydroxyalkanoate units (e.g., 4-hydroxyalkanoate units). 3-hydroxyhexanoate units are particularly preferred.

[0060] The weight-average molecular weight of poly(3-hydroxybutyrate) (A) is not particularly limited, but from the viewpoint of combining the coatability of the coating liquid and the mechanical properties of the coating, it is preferably 100,000 to 400,000, and more preferably 200,000 to 350,000.

[0061] The weight-average molecular weight (hereinafter, sometimes referred to as Mw) of poly(3-hydroxybutyrate) (A) can be determined by gel permeation chromatography (GPC) (Shodex GPC-101 manufactured by Showa Denko Corporation), using polystyrene gel (Shodex K-804 manufactured by Showa Denko Corporation) in the chromatographic column and chloroform as the mobile phase, as the molecular weight after polystyrene conversion.

[0062] In the coating, from the viewpoint of balancing adhesion suppression, water resistance, and oil resistance, the content of poly(3-hydroxyalkanoate) (A) in the total poly(3-hydroxyalkanoate) resin component contained in the coating is preferably 12% by weight or more and 25% by weight or less. From the viewpoint of adhesion suppression, this content is more preferably 13% by weight or more, further preferably 14% by weight or more, and particularly preferably 15% by weight or more. In addition, from the viewpoint of improving oil resistance, it is preferably 24% by weight or less, more preferably 23% by weight or less, and further preferably 22% by weight or less.

[0063] To satisfy the melting characteristics described later, the coating preferably further comprises, in addition to poly(3-hydroxybutyrate) (A), a poly(3-hydroxybutyrate) copolymer (B) containing 3-hydroxybutyrate units and other hydroxyalkanoate units. By including copolymer (B), the coating has a peak temperature (Tma) in the range of 100°C to 155°C as described later, and the resin components are easily melted based on the heating process of the coating described later, and the homogenization of the heated coating is easily achieved, thereby improving the water resistance and oil resistance of the laminate.

[0064] As a specific example of copolymer (B), the above-mentioned copolymer can be cited, wherein poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is preferred.

[0065] From the viewpoint of combining the meltability in the heating process and the productivity of the resin, the proportion of other hydroxyalkanoate units in the total monomer units constituting the poly(3-hydroxybutyrate) copolymer (B) is preferably 10 mol% or more and less than 24 mol%, more preferably 10 mol% or more and less than 20 mol%, and even more preferably 10 mol% or more and less than 18 mol%.

[0066] Furthermore, from the viewpoint of balancing meltability in the heating process and the productivity of the resin, the average content of other hydroxyalkanoate units in the total monomer units contained in the poly(3-hydroxyalkanoate) resin composition is preferably 5 mol% or more and 18 mol% or less, more preferably 6 mol% or more and 16 mol% or less, further preferably 7 mol% or more and 14 mol% or less, and particularly preferably 8 mol% or more and 12 mol% or less.

[0067] The average content ratio of each monomer unit to all monomer units constituting poly(3-hydroxybutyrate) resins or poly(3-hydroxyalkanoate) resins can be determined by methods known to those skilled in the art, such as those described in paragraph

[0047] of International Publication No. 2013 / 147139. The average content ratio refers to the molar ratio of each monomer unit to all monomer units constituting poly(3-hydroxybutyrate) resins or poly(3-hydroxyalkanoate) resins. In the case where the resin being measured is a mixture of two or more resins, it refers to the molar ratio of each monomer unit contained in the mixture as a whole.

[0068] The weight-average molecular weight of the poly(3-hydroxybutyrate) copolymer (B) is not particularly limited, but from the viewpoint of combining the coatability of the coating liquid with the mechanical properties of the coating, it is preferably 100,000 to 400,000, more preferably 200,000 to 350,000. This weight-average molecular weight can be determined by the method described above.

[0069] The specific manufacturing method of poly(3-hydroxybutyrate) copolymer (B) is described, for example, in International Publication No. 2010 / 013483. Furthermore, commercially available products of PHBH include KANEKA Co., Ltd.'s "KANEKA Biodegradable Polymer Green Planet" (registered trademark).

[0070] The weight-average molecular weight of all poly(3-hydroxyalkanoate) resin components contained in the coating is not particularly limited. From the viewpoint of combining the coatability of the coating liquid and the mechanical properties of the coating, it is preferably 100,000 or more and less than 400,000, and more preferably 200,000 to 350,000.

[0071] The coating described above may contain one or more resins other than P3HA, adhesives, dispersants or emulsifiers, pH adjusters, inorganic fillers, pigments, dyes, and other colorants, without compromising the effectiveness of the invention; odor absorbers such as activated carbon and zeolite; fragrances such as vanillin and dextrin; plasticizers, oxidation inhibitors, antioxidants, weather resistance modifiers, ultraviolet absorbers, crystallizing nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and slip modifiers, etc. However, these are optional components, and the coating may not contain these components.

[0072] There are no particular limitations on the resins that can be used in the above coatings other than P3HA, but biodegradable resins are preferred. Specifically, examples include aliphatic polyester resins such as polycaprolactone, polybutylene adipate, polybutylene succinate, and polylactic acid; and aliphatic aromatic polyester resins such as polybutylene adipate and polybutylene azelaate. The amount of these resins other than P3HA can be 50 parts by weight or less, 30 parts by weight or less, or 10 parts by weight or less, relative to 100 parts by weight of P3HA. Alternatively, it can be 5 parts by weight or less, or 1 part by weight or less.

[0073] There is no particular limitation on the thickness of the coating. It can be appropriately determined by considering the required performance and productivity of the coating. For example, it can be 0.5~100μm or 1~30μm.

[0074] The manufacturing method of this embodiment can be carried out by sequentially performing a coating process of coating liquid and a coating formation process based on heating.

[0075] Each process can be carried out continuously on the production line while the strip of substrate is being conveyed. In this case, it is preferable to carry out the substrate release process, the coating liquid application process, the heat-based coating formation process, and the laminate winding process in sequence.

[0076] (Substrate release process)

[0077] First, a roll of substrate is prepared as the base roll. Using a standard sheet conveyor, the substrate is continuously unloaded from the roll while being conveyed. Subsequent coating and subsequent processes are carried out continuously while the substrate is being conveyed in this manner.

[0078] In addition, after continuous papermaking of the paper substrate, it is also possible to directly transport the paper substrate without rolling it into a roll, while continuously carrying out the subsequent coating and subsequent processes.

[0079] There is no particular limitation on the conveying speed of the substrate; it can be set appropriately to take into account production needs, for example, it can be 1~200m / min.

[0080] The above-mentioned surface treatment process, such as corona treatment, can be performed on the substrate before the next coating process.

[0081] (Coating process of the coating solution)

[0082] An aqueous coating solution containing P3HA is applied to at least one side of a conveyed substrate, forming a coating film on at least one side of the substrate layer. This coating process can be performed continuously.

[0083] There are no particular limitations on the method for applying the above-mentioned aqueous coating liquid to the substrate, and known methods can be used appropriately. Specifically, methods such as spraying, spreading, slot coating, air knife coating, roller coating, bar coating, comma coating, doctor blade coating, screen printing, and gravure printing can be used.

[0084] Aqueous coating solutions containing P3HA refer to liquids formed by dispersing resin particles containing at least P3HA in water. In the aforementioned aqueous coating solution, components other than the aforementioned resin particles can be dissolved or dispersed as needed. When this aqueous coating solution is applied to a substrate and the coating is directly laminated onto the paper substrate, the coating solution penetrates into the paper substrate, which has the advantage of easily further improving the adhesion of the coating to the paper substrate.

[0085] The aqueous coating solution containing P3HA is not particularly limited and can be manufactured by the following method. First, after P3HA is produced in the cells of microorganisms, the microbial cells containing P3HA are then broken up in an aqueous dispersion to separate the P3HA from the cells. According to this method, an aqueous dispersion of P3HA microparticles that can retain the small particle size of P3HA produced in the microbial cells can be obtained.

[0086] When separating P3HA from microbial cells in an aqueous dispersion by disrupting the microbial cells containing P3HA, it is preferable to simultaneously stir the microbial cells containing P3HA while simultaneously adding alkali. The pH of the microbial dispersion after alkali addition is preferably 9 to 13.5. If the pH is above 9, P3HA is easily separated from the cells; if the pH is below 13.5, the decomposition of P3HA tends to be inhibited.

[0087] Regarding the disruption of microbial cells, methods include ultrasonic disruption, the use of emulsifying dispersers, high-pressure homogenizers, and grinders. Among these, considering the efficient disruption of nucleic acids (which are the main cause of viscosity increase due to alkali treatment causing P3HA to dissolve from the cells) and the thorough dispersion of insoluble substances other than P3HA, such as cell walls, cell membranes, and insoluble proteins, emulsifying dispersers are preferred, such as Silverson Mixer (Silverson), CLEARMIX (m-tec), and Ebara Milder (EBARA), but are not limited to these.

[0088] Furthermore, the temperature conditions for breaking down the microbial cells and adding alkali are preferably within the range of room temperature to 50°C. If the temperature exceeds 50°C, P3HA is prone to decomposition; therefore, room temperature is preferred.

[0089] From the dispersion obtained by breaking down and alkali treating the microbial cells, a precipitate can be obtained by centrifugation. The precipitate is then washed with water and, if necessary, with methanol. Finally, an appropriate amount of water is added to obtain an aqueous coating solution containing the desired concentration of solid components of P3HA.

[0090] A process can be performed to apply mechanical shearing to the obtained aqueous coating solution, separating the partially aggregated P3HA particles from each other. Applying mechanical shearing can substantially eliminate the aggregates, thereby obtaining an aqueous coating solution containing P3HA with a uniform particle size, which is preferred from this viewpoint. The mechanical shearing of the aqueous coating solution can be performed using, for example, a mixer, a homogenizer, or ultrasound. At this point, the aggregates of P3HA-based resin particles are not firmly formed, so from the viewpoint of simplicity, it is preferable to use a mixer equipped with conventional stirring blades.

[0091] The solid content concentration of P3HA in the above-mentioned aqueous coating solution is preferably 25-65% by weight, more preferably 30-55% by weight, and particularly preferably 35-50% by weight. If the solid content concentration of P3HA in the above-mentioned aqueous coating solution is within the above range, the viscosity of the coating solution will not be too high, it can be coated evenly, and the required coating thickness can be maintained, thereby achieving the effect of not easily generating coating defects.

[0092] From the viewpoint of balancing the productivity of P3HA with the uniformity of coating, the average particle size of the P3HA-based resin particles in the above-mentioned aqueous coating solution 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 size 0.1 μm or more, P3HA can be easily obtained by any method, including microbial production and chemical synthesis. By making the average particle size 50 μm or less, uneven coating can be avoided.

[0093] It should be noted that the average particle size of P3HA resin particles in aqueous coating solutions can be calculated using a common particle size analyzer such as the Microtrac particle size analyzer (Nikkiso, FRA), and the aqueous suspension containing P3HA resin particles is adjusted to a given concentration to be used as the particle size corresponding to 50% of the total accumulation of all normally distributed particles.

[0094] The aforementioned aqueous coating solution may not contain an emulsifier, but it is preferable to include an emulsifier to stabilize the coating solution. Examples of emulsifiers include: anionic surfactants such as sodium dodecyl sulfate and sodium oleate; cationic surfactants such as dodecyltrimethylammonium chloride; nonionic surfactants such as glycerol fatty acid esters and sorbitan fatty acid esters; polyvinyl alcohol derivatives such as polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, sulfonated polyvinyl alcohol, and ethylene-modified polyvinyl alcohol; cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose; starch derivatives such as starch, oxidized starch, or etherified starch; and water-soluble polymers such as chitin, chitosan, casein, and gum arabic. Only one of these can be used, or two or more can be used in combination. From the viewpoint of easily preparing an aqueous solution when adding the coating solution industrially, polyvinyl alcohol is preferred.

[0095] There is no particular limitation on the amount of emulsifier added, but it is preferably 1 to 10% by weight relative to the solid content of P3HA. If the amount of emulsifier added is 1% by weight or more, there is a tendency to obtain a stabilizing effect due to the emulsifier; if it is 10% by weight or less, it is possible to avoid the decrease in physical properties, coloring, etc. caused by excessive emulsifier mixed into P3HA.

[0096] The emulsifier described above can be added to the aqueous dispersion after microbial cell disruption / alkali treatment, centrifugation, and water washing. In the case of methanol washing, it can be added after methanol washing, before or after adding an appropriate amount of water to adjust the solid component concentration of P3HA.

[0097] There is no particular limitation on the amount of P3HA applied; it can be appropriately determined by considering the required performance and productivity of the coating. Specifically, based on dry weight, it is preferably 1.0 g / m³. 2 Above and 80g / m 2 The following is more preferably 5.0 g / m 2 Above and 60g / m 2 The following is a further preferred value: 10 g / m 2 Above and 50g / m 2 The following applies. If the amount of P3HA applied is within the above range, defects such as pinholes can be prevented, the coating will have sufficient strength to withstand use, and it will effectively exhibit water and oil resistance.

[0098] (Heat-based coating formation process)

[0099] In the heating process, the coating film formed in the coating process is heated until its surface temperature reaches above 170°C, forming a coating layer and thus obtaining a laminate. In this process, while water evaporates, the P3HA-based resin particles contained in the aqueous coating solution melt and bond together, forming a resin layer with relatively high uniformity. Therefore, a coating that meets the specific melting characteristics described later can be formed.

[0100] By heating the coating until the surface temperature reaches 170°C or higher, the P3HA resin particles can be fully melted and bonded together, thus reducing coating defects and improving the water and oil resistance of the resulting laminate.

[0101] Those skilled in the art can appropriately set an upper limit for the surface temperature of the coating. From the viewpoint of avoiding problems such as decreased mechanical strength and breakage of the laminate due to excessive drying of the substrate layer and thermal decomposition of P3HA, it is preferable to set the temperature below 200°C, more preferably below 190°C. It can also be set below 180°C.

[0102] The heating process can be carried out using known heating methods, such as hot air heating, infrared heating, microwave heating, roller heating, hot plate heating, etc., which can be used alone or in combination of two or more.

[0103] Alternatively, this heating process can be carried out continuously using equipment commonly used in paper coating. Specifically, it can be carried out by passing a substrate with a coating on one side through a drying oven set to a specific temperature. Alternatively, it can be carried out by contacting or clamping the substrate with a coating on one side with rollers set to a specific temperature.

[0104] To achieve a surface temperature of 170°C or higher for the coating, it is preferable to set the heating device to a temperature higher than the target temperature. However, if the heating device is set too high, it will be difficult to control the surface temperature. Therefore, it is preferable to set the temperature to approximately 10-20°C higher than the target temperature.

[0105] Furthermore, it is preferable to heat at the set temperature described above for at least 1 minute. By heating for at least 1 minute, the surface temperature of the coating can be reliably brought to the target temperature. Preferably, it is 1.5 minutes or more. There is no particular upper limit, but from a production point of view, 3 minutes or less is preferred.

[0106] Furthermore, in the embodiment of Patent Document 2, it is described that after applying the coating liquid, the temperature of the drying oven is set to 190°C and heated for 10 seconds to form a resin layer. It is speculated that the surface temperature of the coating film did not reach 170°C or higher because the heating time was too short.

[0107] Regarding the laminate manufactured according to this embodiment, in the crystallization melting curve based on differential scanning calorimetry, the coating containing P3HA has at least one peak temperature (Tmb) in the range of 155 to 175°C. By allowing the resin component showing this Tmb to act as a crystal nucleus, the curing of P3HA after the heating process is promoted, and adhesion between the laminates can be suppressed. If there is no peak temperature in the range above 155°C, adhesion is likely to occur. Tmb is preferably in the range of 160 to 170°C.

[0108] Furthermore, the coating preferably has at least one peak temperature (Tma) in the range of 100-155°C, in addition to Tmb. Since the resin component exhibiting this Tma readily melts during the heating process, it is easier to homogenize the coating through heating, thereby improving the water and oil resistance of the laminate. Tma is preferably in the range of 110-145°C, and more preferably in the range of 120-135°C.

[0109] The temperature difference between Tma and Tmb is not particularly limited, but is preferably 10°C or more, more preferably 20°C or more, even more preferably 25°C or more, and particularly preferably 30°C or more. The upper limit of the temperature difference between Tma and Tmb is not particularly limited, but from the viewpoint of ease of manufacture, it is, for example, 60°C or less, and preferably 50°C or less.

[0110] In this application specification, the peak temperature of the crystallization melting curve in differential scanning calorimetry is defined as follows: 2-5 mg of the coating of the test object is filled into an aluminum disk. Using a differential scanning calorimeter, the temperature is increased from 20°C to 190°C at a rate of 10°C / min under a nitrogen flow to melt the resin and obtain the crystallization melting curve. In the obtained crystallization melting curve, the peak temperature of the melting point peak existing in the range of 100-155°C is designated as Tma, and the peak temperature of the melting point peak existing in the range of 155-175°C is designated as Tmb. Furthermore, if multiple melting point peaks are observed in the range of 100-155°C, the peak temperature of the highest peak is designated as Tma; if multiple melting point peaks are observed in the range of 155-175°C, the peak temperature of the highest peak is designated as Tmb.

[0111] A laminate containing a coating exhibiting such melting properties can be manufactured, for example, by controlling the composition of P3HA contained in the coating as described above, and heating the coating within the temperature range described above.

[0112] (Roll-up process of laminated materials)

[0113] A roll-shaped laminate can be obtained by winding the laminate obtained as described above using a take-up roller. According to this embodiment, since the coating exhibits the specific melting characteristics described above, adhesion between the wound laminates is suppressed. Therefore, after the winding process, the laminate can be released from the roll-shaped laminate without resistance.

[0114] In the laminate that can be manufactured by this embodiment, the coating is preferably the outermost layer. In this case, the coating can function as a heat-sealing layer, a water-resistant layer, and / or an oil-resistant layer, etc.

[0115] The aforementioned heat-sealable layer refers to a layer with heat-sealing adaptability; specifically, it is a layer that can be bonded to the object being bonded by heating and pressing. The object being bonded can be the same heat-sealable layer, the aforementioned substrate, or an article made of other materials.

[0116] In another embodiment of this disclosure, other layers may be laminated on top of the aforementioned coating. In this case, the aforementioned coating can function as an anchoring coating between the substrate and the other layers. The other layers are not particularly limited and may be other resin layers or inorganic layers.

[0117] Regarding the side opposite to the side where the coating is deposited, the surface of the substrate layer may be exposed, or other layers may be deposited on the surface of the substrate layer. These other layers may be layers corresponding to the coating, or layers other than the coating.

[0118] [Molded body]

[0119] The laminate (hereinafter also referred to as "this laminate") manufactured by this embodiment can be molded into a molded body (hereinafter also referred to as "this molded body") by molding it into a given shape. This molded body is a molded body comprising the above-described laminate and having a desired size and shape. This molded body is formed from a laminate containing a coating containing P3HA, and is therefore advantageous in various applications.

[0120] This molded body can be any material containing this laminate and is not particularly limited. Examples include: paper, film, sheet, tube, plate, rod, container (e.g., bottle container), bag, component, etc. From the viewpoint of countermeasures against marine pollution, this molded body is preferably a packaging bag, lid material, or container such as a cup or tray.

[0121] In one embodiment of this disclosure, the molded body may be the laminate itself or a product of the laminate after secondary processing.

[0122] This laminate, through secondary processing, can be used as a molded body for various packaging containers such as shopping bags, various bags, food / snack packaging materials, cups, trays, and cartons (in other words, suitable for various fields such as food, cosmetics, electronics, medical, and pharmaceuticals). This laminate has high adhesion to the substrate and good heat resistance, making it more suitable as a container for liquids, especially for beverage cups such as instant noodles, instant soup, and coffee, as well as trays for dishes, boxed meals, and microwaveable foods. This laminate also exhibits excellent water and oil resistance, making it suitable as a packaging material for packaging foods containing water or oil.

[0123] The aforementioned secondary processing can be performed using the same methods as conventional resin-laminated or coated paper, i.e., using various bag-making machines, filling and packaging machines, etc. Alternatively, it can be processed using paper cup forming machines, punching machines, box-making machines, etc. In these processing machines, the bonding method for this laminate can use known techniques, such as heat sealing, pulse sealing, ultrasonic sealing, high-frequency sealing, hot air sealing, flame sealing, etc.

[0124] The heat sealing described above can be performed by heating the laminate to heat-melt at least a portion of the coating of the laminate. Heat-melting refers to a process in which at least a portion of the coating is heat-melted and then firmly bonded to another surface. This other surface is not particularly limited and can be the surface of the coating of the laminate, the surface of the substrate layer of the laminate, or the surface of an article different from the laminate.

[0125] The heat-sealing temperature of this laminate varies depending on the bonding method. For example, when using a heated heat-sealing tester with a sealing strip, it can be set such that the surface temperature of the coating typically reaches 200°C or below, preferably 180°C or below, and more preferably 160°C or below. Within this range, resin leaching near the seal can be avoided, ensuring appropriate coating thickness and sealing strength. Since this laminate achieves good adhesion even when heat-sealed at low temperatures, the aforementioned surface temperature can be 150°C or below, or even 140°C or below. Furthermore, when using a heated heat-sealing tester with a sealing strip, the lower limit of the surface temperature is typically 100°C or above, preferably 110°C or above, and more preferably 120°C or above. Within this range, proper adhesion of the seal can be ensured.

[0126] The heat-sealing pressure of this laminate varies depending on the bonding method. For example, when using a heated heat-sealing tester with a sealing strip, it is typically 0.1 MPa or higher, preferably 0.5 MPa or higher. Within this range, proper adhesion of the seal is ensured. Furthermore, the upper limit of the heat-sealing pressure when using a heated heat-sealing tester with a sealing strip is typically 1.0 MPa or lower, preferably 0.75 MPa or lower. Within this range, thinning of the film thickness at the sealing end is avoided, ensuring sealing strength.

[0127] Furthermore, to improve its physical properties, this molded body can also be composited with molded bodies made of materials different from this molded body (e.g., fibers, filaments, ropes, textiles, woven fabrics, nonwoven fabrics, paper, films, sheets, tubes, plates, rods, containers, bags, components, foams, etc.). These materials are also preferably biodegradable.

[0128] Preferred embodiments of this disclosure are set forth in the following items, but the invention is not limited to the following items.

[0129] [Project 1]

[0130] A method for manufacturing a laminate, the laminate having a substrate layer and a coating layer laminated on at least one side of the substrate layer, the method comprising:

[0131] The process of applying an aqueous coating solution of a poly(3-hydroxyalkanoate) resin composition to a substrate to form a coating film; and

[0132] The process of heating the coating film until its surface temperature reaches 170°C or higher to form the coating layer.

[0133] In the crystallization melting curve based on differential scanning calorimetry, the coating has a peak temperature (Tmb) in the range of 155°C to 175°C.

[0134] [Project 2]

[0135] According to the manufacturing method of the laminated body described in Project 1, wherein...

[0136] In the crystallization melting curve based on differential scanning calorimetry, the coating further exhibits a peak temperature (Tma) in the range of 100°C to 155°C.

[0137] [Project 3]

[0138] According to the manufacturing method of the laminated body described in Project 1 or 2, wherein,

[0139] The poly(3-hydroxyalkanoate) resin composition comprises poly(3-hydroxybutyrate) (A).

[0140] [Project 4]

[0141] According to the manufacturing method of the laminated body described in Project 3, wherein...

[0142] In the poly(3-hydroxyalkanoate) resin composition, the content of poly(3-hydroxybutyrate) (A) is 13% by weight or more and 22% by weight or less.

[0143] [Project 5]

[0144] According to the manufacturing method of the laminated body described in item 3 or 4, wherein...

[0145] The poly(3-hydroxyalkanoate) resin composition further comprises a poly(3-hydroxyalkanoate) copolymer (B) having 3-hydroxybutyrate units and other hydroxyalkanoate units.

[0146] [Project 6]

[0147] According to the manufacturing method of the laminated body described in Project 5, wherein...

[0148] The other hydroxyalkanoate units in the poly(3-hydroxybutyrate) copolymer (B) are present in an amount of 10 mol% or more and less than 24 mol%.

[0149] [Project 7]

[0150] According to the manufacturing method of the laminated body described in item 5 or 6, wherein...

[0151] The average content of the other hydroxyalkanoate units in all poly(3-hydroxyalkanoate) resin components in the poly(3-hydroxyalkanoate) resin composition is more than 5 mol% and less than 18 mol%.

[0152] [Project 8]

[0153] The method for manufacturing a laminate according to any one of items 1 to 7, wherein,

[0154] The weight-average molecular weight (Mw) of all poly(3-hydroxyalkanoate) resin components contained in the poly(3-hydroxyalkanoate) resin composition is greater than 100,000 and less than 400,000.

[0155] [Project 9]

[0156] The method for manufacturing a laminate according to any one of items 1 to 8 further includes:

[0157] The process of rolling the laminate into a roll.

[0158] [Project 10]

[0159] A method for manufacturing a molded article, the method comprising:

[0160] The process of manufacturing a laminate using the manufacturing method described in any one of items 1 to 9, and

[0161] A process of hot-melting at least a portion of the coating.

[0162] Example

[0163] The present invention will be specifically described below through embodiments, but the present invention is not limited to its technical scope by these embodiments.

[0164] The substances used in the examples and comparative examples are shown below.

[0165] [Poly(3-hydroxyalkanoate) resins (P3HA resins)]

[0166] PHB: Poly(3-hydroxybutyrate) (weight-average molecular weight 350,000 g / mol)

[0167] It was manufactured according to the method described in Comparative Example 1 of International Publication No. 2004 / 041936.

[0168] P3HB3HH-11:P3HB3HH (average content ratio 3HB / 3HH=89 / 11 (mol% / mol%), weight-average molecular weight is 260,000 g / mol), was manufactured according to the method described in International Publication No. 2008 / 010296.

[0169] When a mixture of two or more poly(3-hydroxyalkanoate) resins is used as the poly(3-hydroxyalkanoate) resin component, the average 3HH ratio in Table 1 is the average value calculated based on the 3HH ratio in each poly(3-hydroxyalkanoate) resin and the weight ratio of each poly(3-hydroxyalkanoate) resin.

[0170] In addition, the monomer composition ratio and weight-average molecular weight of the P3HA resin were determined by the following methods.

[0171] <Determination of the monomer composition ratio of P3HB3HH>

[0172] The monomer composition ratio of P3HB3HH was determined as follows. To about 20 mg of P3HB3HH, 1 mL of a sulfuric acid-methanol mixed solution (15:85) and 1 mL of chloroform were added and sealed, and heated at 100 °C for 140 minutes, whereby the methyl ester of the P3HB3HH decomposition product was obtained. After cooling, 0.5 mL of deionized water was added thereto and mixed well, and then left standing until the aqueous layer and the organic layer were separated. Then, the monomer unit composition of the P3HB3HH decomposition product in the separated organic layer was analyzed by capillary gas chromatography. The ratio of 3-hydroxyhexanoate was calculated based on the obtained peak areas.

[0173] <Determination of the weight-average molecular weight>

[0174] The weight-average molecular weights of P3HB3HH and PHB were determined by the following method: First, the resin to be measured was dissolved in chloroform, heated in a warm water bath at 60 °C for 0.5 hours, filtered the soluble components with a disposable filter with a pore size of 0.45 μm made of PTFE, and using the filtrate, GPC measurement was carried out under the following conditions to obtain the value of the weight-average molecular weight.

[0175] GPC measurement device: High Performance Liquid Chromatography 20A system manufactured by Shimadzu Corporation

[0176] Chromatographic column: K-G 4A (1 piece), K-806M (2 pieces) manufactured by Showa Denko KK

[0177] Sample concentration: 1 mg / ml

[0178] Eluent: Chloroform solution

[0179] Eluent flow rate: 1.0 ml / minute

[0180] Sample injection volume: 100 μL

[0181] Analysis time: 30 minutes

[0182] Standard sample: Standard polystyrene

[0183] [Resin dispersions and aqueous coating solutions]

[0184] According to the method described in International Publication No. 2015 / 146195, a resin dispersion with a solid component concentration of 50% by weight of P3HA resin was obtained.

[0185] A 2% aqueous solution was added to 1 part by weight of methylcellulose (METOLOSE SM-400, manufactured by Shin-Etsu Chemical) relative to 100 parts by weight of the resin in the above resin dispersion and stirred to obtain an aqueous coating solution.

[0186] The evaluation methods implemented in the embodiments and comparative examples are described below.

[0187] [Determination of the surface temperature reached by the coating]

[0188] The surface temperature of the coating was measured as follows: A Samolabel (registered trademark) (manufactured by Nikyu Giken Kogyo) was affixed to the coated paper surface, and the temperature of the label was measured when it passed through a heated oven under coating conditions. Indicates temperature.

[0189] [Anti-blocking properties of coated paper after winding]

[0190] A gravure coating machine was used to coat paper with an aqueous coating solution. Then, the degree of adhesion (bonding) between the coated and uncoated surfaces was evaluated when the coated paper was unwound after being heated to form a film.

[0191] <Evaluation>

[0192] ○: Can be unrolled evenly

[0193] △: Partial adhesion, but can be evenly unwound without any coating abnormalities or damage.

[0194] ×: Severe adhesion, material damage occurs during unwinding, making unwinding impossible.

[0195] [Evaluation of the water resistance of coated paper]

[0196] According to the "Paper and Board - Water Absorption Test Method - Cobb Method" specified in JIS P 8140:1998, the water absorption (Cobb value) was measured at any two points on the coated surface of the coated paper using room temperature water for a contact time of 1800 seconds.

[0197] The average of the water absorption (Cobb value) measured at two points was used as the water resistance value, and the water resistance was evaluated according to the following criteria. If the evaluation is ○, there is no problem in practical use.

[0198] <Evaluation Criteria>

[0199] ○: The average water absorption (Cobb value) is 3g / m³. 2 the following.

[0200] ×: The average water absorption (Cobb value) exceeds 3g / m³. 2 And it is 10g / m 2 the following.

[0201] [Evaluation of the oil resistance of coated paper]

[0202] For any two points on the A4-sized coated surface of the coated paper, Ageless sealing inspection fluid (Mitsubishi Gas Chemical) was sprayed, and then it was confirmed after 120 seconds whether there was any penetration to the back of the sprayed surface.

[0203] For the two points of the test, oil resistance was evaluated according to the following criteria. If the evaluation is ○ or △, it is judged that there is no problem in actual use.

[0204] <Evaluation Criteria>

[0205] ○: Ageless test fluid did not penetrate the back at all.

[0206] △: Ageless inspection fluid did not penetrate to the back side, but some penetration into the coating can be observed.

[0207] ×: Ageless test fluid has seeped into more than one spot on the back.

[0208] [Heat-sealing adhesion between coatings]

[0209] Cut each coated paper into 25mm wide pieces. Using a heat sealer (TP-701-B, manufactured by Tester Sangyo Co., Ltd.), press the coatings of the coated papers together under the following conditions: heating temperature: 120℃, 140℃, 160℃, 180℃, or 200℃; surface pressure: 0.1MPa; sealing time: 0.5 seconds. After the heat seal strip detaches from the coated paper for 2 seconds, peel off the sealing surface by hand. Visually inspect the peeled surface and evaluate it according to the following criteria. If the peeling condition is ○ or △, it is judged that there is no problem in actual use.

[0210] <Evaluation Criteria>

[0211] ○: Paper material damage

[0212] △: Partial material damage to the paper

[0213] ×: The paper was not damaged.

[0214] [Weight per unit area of ​​the resin component in the coating]

[0215] Each coated paper was cut into 10cm×10cm pieces and weighed. The weight of the resin component was obtained by subtracting the weight of the original paper from the original paper weight and multiplying by 100.

[0216] Differential Scanning Calorimetry

[0217] Two to five mg of the resin component of the coating was filled into an aluminum disk. Using a differential scanning calorimeter, the temperature was increased from 20°C to 190°C at a rate of 10°C / min under a nitrogen gas flow to melt the resin component and obtain a crystallization melting curve.

[0218] In the obtained crystallization melting curve, the peak temperature of the melting point peak that exists in the range of above 100℃ and below 155℃ is set as Tma.

[0219] Additionally, the peak temperature of the melting point peak existing in the range of 155°C above and 175°C is set as Tmb. In cases where multiple melting point peaks are observed in the range of 155°C above and 175°C below, the melting point temperature of the highest peak is set as Tmb.

[0220] (Example 1)

[0221] As a component of the P3HA-based resin, an aqueous coating solution was prepared by mixing 86.5 parts by weight of P3HB3HH-11 and 13.5 parts by weight of PHB. The aqueous coating solution was then applied to a surface area of ​​50 g / m² using a gravure coating machine. 2 Bleached kraft paper (manufactured by Marusumi Paper Co., Ltd. / Starpack A) was then heated in a hot air oven set to 180°C for 2 minutes, forming a coating at a surface temperature of 170°C. The resin component had a unit area weight of 15 g / m². 2 .

[0222] The peak temperatures (Tma, Tmb) of the melting point were determined by differential scanning calorimetry for the obtained coated paper. In addition, the resistance to tack, water, oil and heat-sealing after winding were evaluated and the results are shown in Table 1.

[0223] (Examples 2-4, Comparative Examples 1-4)

[0224] The resin formulation and the surface temperature of the coating were modified as shown in Table 1. Otherwise, the coating was formed in the same manner as in Example 1, and coated paper was produced. The same measurements and evaluations as in Example 1 were performed, and the results are summarized in Table 1.

[0225]

[0226] As demonstrated in Examples 1-4, when the surface temperature reached during coating is set to 170°C, exceeding the melting point of the resin, the coated paper exhibits excellent anti-blocking properties after winding, and can also produce coated paper with excellent water resistance, oil resistance, and heat-sealing adhesion over a wide heat-sealing temperature range. Specifically, in Examples 1-4, crystals with a Tmb of 163°C or 164°C and a high melting point of 155°C or higher were present. It is believed that by making these crystal nuclei, the curing of the molten resin can proceed, thereby exhibiting good anti-blocking, water resistance, oil resistance, and heat-sealing properties.

[0227] On the other hand, in Comparative Examples 1 and 2, there was no Tmb or the peak temperature was below 155°C, so there was a lack of adhesion resistance, and Comparative Example 1 also lacked heat-sealing properties on the high-temperature side.

[0228] Furthermore, in Comparative Examples 3 and 4, although the same amount of PHB as in Example 2 was included, the surface temperature of the coating film during coating formation was low, resulting in insufficient resin melting and coating defects such as pinholes. This was presumably due to a lack of oil resistance or water resistance.

Claims

1. A method for manufacturing a laminate, the laminate having a substrate layer and a coating layer laminated on at least one side of the substrate layer, the method comprising: The process of applying an aqueous coating solution of a poly(3-hydroxyalkanoate) resin composition to a substrate to form a coating film; as well as The process of heating the coating film until its surface temperature reaches 170°C or higher to form the coating layer. In the crystallization melting curve based on differential scanning calorimetry, the coating has a peak temperature (Tmb) in the range of 155°C to 175°C.

2. The method for manufacturing a laminate according to claim 1, wherein, In the crystallization melting curve based on differential scanning calorimetry, the coating further exhibits a peak temperature (Tma) in the range of 100°C to 155°C.

3. The method for manufacturing a laminate according to claim 1 or 2, wherein, The poly(3-hydroxyalkanoate) resin composition comprises poly(3-hydroxybutyrate) (A).

4. The method for manufacturing a laminate according to claim 3, wherein, In the poly(3-hydroxyalkanoate) resin composition, the content of poly(3-hydroxybutyrate) (A) is 13% by weight or more and 22% by weight or less.

5. The method for manufacturing a laminate according to claim 3, wherein, The poly(3-hydroxyalkanoate) resin composition further comprises a poly(3-hydroxyalkanoate) copolymer (B) having 3-hydroxybutyrate units and other hydroxyalkanoate units.

6. The method for manufacturing a laminate according to claim 5, wherein, The other hydroxyalkanoate units in the poly(3-hydroxybutyrate) copolymer (B) are present in an amount of 10 mol% or more and less than 24 mol%.

7. The method for manufacturing a laminate according to claim 5, wherein, The average content of the other hydroxyalkanoate units in all poly(3-hydroxyalkanoate) resin components in the poly(3-hydroxyalkanoate) resin composition is more than 5 mol% and less than 18 mol%.

8. The method for manufacturing a laminate according to claim 1 or 2, wherein, The weight-average molecular weight (Mw) of all poly(3-hydroxyalkanoate) resin components contained in the poly(3-hydroxyalkanoate) resin composition is greater than 100,000 and less than 400,000.

9. The method for manufacturing a laminate according to claim 1 or 2, further comprising: The process of rolling the laminate into a roll.

10. A method for manufacturing a molded article, the method comprising: The process of manufacturing a laminate using the manufacturing method described in claim 1 or 2, and A process of hot-melting at least a portion of the coating.

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