Stacked body and molded body

Abstract

A laminate having a substrate layer, and a coating layer laminated to at least one side of the substrate layer, wherein the coating layer contains a poly(3-hydroxybutyrate)-based resin, 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 obtained by differential scanning calorimetry, and the temperature difference between Tma and Tmb is 10°C or more.

Description

TECHNICAL FIELD

[0001] The present application relates to a laminate having a layer containing a poly(3-hydroxybutyrate)-based resin, and 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 serious, and the popularization of biodegradable plastics that decompose in the natural environment is expected.

[0003] As such biodegradable plastics, various plastics are known, and among them, poly(3-hydroxybutyrate)-based resins are thermoplastic polyesters produced and accumulated in the cells of various 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] In addition, a laminate in which a layer containing a poly(3-hydroxybutyrate)-based resin is laminated on a substrate having biodegradability such as paper is a material in which both the resin and the substrate have biodegradability, and thus is promising from the viewpoint of environmental protection (for example, see Patent Literature 1).

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: International Publication No. 2019 / 239913 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] With the laminate in which a layer containing a poly(3-hydroxybutyrate)-based resin is laminated on a substrate as reported so far, in the case where the resin layer is bonded by heat sealing at the time of molding processing, the range of applicable heat sealing temperature is limited. In particular, when heat sealing is performed at a high temperature, in order to exhibit a good bonding strength, a long time is required after heat sealing, and there is a problem that the production efficiency is reduced.

[0010] In view of the above circumstances, an object of the present application is to provide a laminate having a layer containing a poly(3-hydroxybutyrate)-based resin, which can bond the resin layer by heat sealing at the time of molding processing of the laminate, and the range of applicable heat sealing temperature is large, and even if the resin is heated to a temperature at which sufficient bonding is possible, a good bonding strength can be exhibited in a short time after heating.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] As a result of intensive studies made by the present inventors et al. in order to solve the above problem, it has been found that the above problem can be solved by forming a coating layer containing a poly(3-hydroxybutyrate)-based resin in such a manner that it exhibits specific peaks in a crystalline melting curve obtained by differential scanning calorimetry, thereby completing the present application.

[0013] That is, the present application relates to a laminate having a substrate layer, and a coating layer laminated to at least one surface of the substrate layer, wherein the above coating layer contains a poly(3-hydroxybutyrate)-based resin, and 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 obtained by differential scanning calorimetry, and the temperature difference between Tma and Tmb is 10°C or more.

[0014] Preferably, the ratio (ΔHb / ΔHa) of the crystalline melting enthalpy (ΔHa) of the peak in the range of 100 to 150°C to the crystalline melting enthalpy (ΔHb) of the peak in the range of 150 to 170°C in the crystalline melting curve obtained by differential scanning calorimetry of the above coating layer is 0.01 to 2.

[0015] Preferably, the weight average molecular weight of the above poly(3-hydroxybutyrate)-based resin is 50,000 to 650,000.

[0016] Preferably, the above poly(3-hydroxybutyrate)-based resin contains at least one poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0017] Preferably, the above poly(3-hydroxybutyrate)-based resin contains at least two poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having different content ratios of constituent monomers.

[0018] Preferably, the above poly(3-hydroxybutyrate)-based resin contains a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having a content ratio of 3-hydroxyhexanoate units of 8 mol% or more and 25 mol% or less. More preferably, the above poly(3-hydroxybutyrate)-based resin further contains a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having a content ratio of 3-hydroxyhexanoate units of less than 8 mol% or a poly(3-hydroxybutyrate).

[0019] In addition, the present application also relates to a method for producing the above laminate, which comprises a step of applying an aqueous coating solution containing the above poly(3-hydroxybutyrate)-based resin to a substrate to form a coating film, and a step of heating the above coating film at a temperature of 130°C or more and 170°C or less to form the above coating layer.

[0020] Furthermore, the present application also relates to a molded body containing the above laminate.

[0021] Further, the present application also relates to a method for producing the above-mentioned molded body, which comprises a step of heat-sealing the above-mentioned coating.

[0022] Effects of the Invention

[0023] According to the present application, it is possible to provide a laminate having a layer containing a poly(3-hydroxybutyrate)-based resin, which can be bonded by heat-sealing at the time of molding processing of the laminate, and which has a wide range of applicable heat-sealing temperature, and even if the resin is heated to a temperature at which it can be sufficiently bonded, it can exhibit good bonding strength in a short time after heating. By using the laminate of the present application, it is possible to shorten the cycle time of heat-sealing, and improve the production efficiency of the molded body. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a crystalline melting curve obtained from differential scanning calorimetry analysis measured in Example 1. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present application will be described, but the present application is not limited to the following embodiments.

[0026] [Laminate]

[0027] The laminate of one embodiment of the present application has a substrate layer, and a coating layer laminated to at least one surface of the substrate layer, and the above-mentioned coating layer contains a poly(3-hydroxybutyrate)-based resin.

[0028] The above-mentioned coating layer can be laminated to only one surface of the above-mentioned substrate layer, or can be laminated to both surfaces. In addition, the above-mentioned coating layer can be laminated to the substrate layer with other layers interposed therebetween, or can be directly laminated to the substrate layer without other layers interposed therebetween. Another layer can be further laminated on the above-mentioned coating layer.

[0029] (Substrate layer)

[0030] The above-mentioned substrate layer is not particularly limited as long as it is a layer to which a coating layer can be laminated, and is preferably a layer having biodegradability. By making the above-mentioned substrate layer a layer having biodegradability, the entire laminate including the coating layer has biodegradability, and it is more advantageous as a raw material for solving the problem of ocean pollution.

[0031] In addition, from the viewpoint of preventing the coating liquid from flowing over the surface to form a coating film of uneven thickness, the above-mentioned substrate layer is preferably water-absorbing.

[0032] As the substrate layer having biodegradability, there is no particular limitation, and examples that can be listed include paper (main component: cellulose), cellophane, cellulose ester; polyvinyl alcohol, polyamino acid, polyglycolic acid, pullulan, or a product obtained by vapor-depositing aluminum, silicon dioxide, or the like inorganic substance on these substrates, and the like. Among them, from the viewpoint of excellent heat resistance and low cost, paper is preferable. The type of paper is not particularly limited, and examples that can be listed include raw material paper for paper cups, kraft paper, all-wood pulp paper, coated paper, thin-layer paper, cellophane, paperboard, and the like. The type of paper can be appropriately selected depending on the purpose of the laminate. To the paper, a water-resistant agent, a water-repellent agent, an inorganic substance, or the like can be added as needed, and surface treatment such as oxygen barrier layer coating, water vapor barrier coating, or the like can be performed.

[0033] The above substrate layer can be subjected to surface treatment such as corona treatment, flame treatment, anchor coating treatment, or the like. These surface treatments can be performed alone or in combination.

[0034] The above coating layer can be formed by applying an aqueous coating liquid to one or both surfaces of the substrate layer, and then heating and drying and film-forming as described later. Therefore, in the case where the above coating layer is directly laminated to the substrate layer without interposing other layers, a part of the aqueous coating liquid will penetrate into the substrate layer during the manufacturing process of the laminate, and an intermediate layer containing a part of the poly(3-hydroxybutyrate)-based resin from the coating layer and a part of the substrate from the substrate layer will be formed between the coating layer and the substrate layer. Such an intermediate layer is not seen in the laminate manufactured by extrusion molding by a lamination method or the like, and is a characteristic configuration of the laminate containing the coating layer. Note that the form of the intermediate layer in the laminate can be easily observed, for example, using a scanning electron microscope (SEM) or the like.

[0035] (coating layer)

[0036] The above coating layer contains at least a poly(3-hydroxybutyrate)-based resin. In the present specification, the poly(3-hydroxybutyrate)-based resin (hereinafter, also referred to as P3HB-based resin) is an aliphatic polyester resin that can be produced by microorganisms with 3-hydroxybutyrate as a repeating unit.

[0037] The P3HB-based resin can be poly(3-hydroxybutyrate) with only 3-hydroxybutyrate as a repeating unit, or can be a copolymer of 3-hydroxybutyrate and another hydroxyalkanoate.

[0038] The P3HB-based resin can be a mixture of a homopolymer and one or two 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.

[0039] 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), and the like can be exemplified. Among them, from the viewpoint of being industrially easily produced, P3HB, P3HB3HH, P3HB3HV, and P3HB4HB are preferable.

[0040] In addition, by changing the composition ratio of the repeating units, the melting point and the crystallinity change, and as a result, the Young's modulus, the heat resistance, and the like can be changed, and the properties between polypropylene and polyethylene can be imparted. Furthermore, as described above, it is industrially easily produced, and is a useful plastic in terms of the properties, and from such a viewpoint, P3HB3HH as a copolymer of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid is more preferable. In addition, from the viewpoint of being able to lower the melting point and to perform molding processing at a low temperature, P3HB3HH is preferable.

[0041] In one embodiment of the present application, the P3HB-based resin preferably contains at least one kind of P3HB3HH, and particularly preferably contains at least two kinds of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) having different proportions of the constituent monomers. In addition, it is also preferable to contain at least one kind of P3HB3HH and P3HB.

[0042] As the microorganism for producing the P3HB-based resin, any microorganism having the ability to produce the P3HB-based resin can be used without particular limitation. For example, as the P3HB-producing bacterium, the first discovered Bacillus megaterium in 1925, and other natural microorganisms such as Cupriavidus necator (old classification: Alcaligenes eutrophus, Ralstonia eutropha), Alcaligenes latus, and the like can be exemplified. Among these microorganisms, it is known that P3HB is accumulated in the bacterial cells.

[0043] Further, as a production strain of a copolymer of 3-hydroxybutyrate and other hydroxyalkanoate, there are known Aeromonas caviae as a P3HB3HV and P3HB3HH production strain, Alcaligenes eutrophus as a P3HB4HB production strain, and the like. In particular, regarding P3HB3HH, in order to improve the productivity of P3HB3HH, it is more preferable that Alcaligenes eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038) into which a gene of a P3HA synthase group is introduced (T. Fukui, Y. Doi, J. Bacteriol., 179, p4821-4830 (1997)) or the like. A microbial cell in which P3HB3HH is accumulated in the cell 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 are introduced depending on a P3HB-based resin to be produced can be used, and optimization of the culture conditions including the substrate species can be performed.

[0044] Further, P3HB3HH can be produced, for example, by the method described in International Publication No. 2010 / 013483. As a commercially available product of P3HB3HH, for example, "Tokumaru Biodegradable Polymer PHBH (registered trademark)" and the like manufactured by Tokumaru Corporation can be mentioned.

[0045] As the P3HB-based resin, P3HB3HH having a content ratio of 8 to 25 mol% of 3HH units is preferable. The composition ratio of each constituent monomer in this P3HB3HH is preferably 3HB / 3HH = 92 to 75 / 8 to 25 (mol% / mol%), and more preferably 3HB / 3HH = 90 to 82 / 10 to 18 (mol% / mol%). When the content ratio of 3HH units in this P3HB3HH is 8 mol% or more, a coating layer having the melting properties described later can be easily formed. Further, the crystallization speed of P3HB3HH having a content ratio of 3HH units of 25 mol% or less does not become too slow, and production is easier. Note that the composition ratio of each constituent monomer can be determined by measuring P3HB3HH by NMR.

[0046] P3HB3HH having a content ratio of 8 to 25 mol% of 3HH units can be used as a single P3HB-based resin, and this P3HB3HH can be used in combination with P3HB3HH having a content ratio of 3HH units of less than 8 mol% or P3HB (a homopolymer of 3HB). By this combination, the ratio ΔHb / Δha described later can be made a larger value than in the case of single use, and even if the heat-sealing temperature is increased to a temperature at which sufficient adhesion is possible, a good adhesion strength can be exhibited in a short time after heat-sealing.

[0047] The content ratio of 3HH units in P3HB3HH in which the content ratio of 3HH units is less than 8 mol% is preferably 5 mol% or less, more preferably 3 mol% or less, and further preferably 1 mol% or less. The lower limit of the content ratio of 3HH units in this P3HB3HH is not particularly limited, and can be, for example, 0.1 mol% or more.

[0048] The blending amount of P3HB3HH or P3HB in which the content ratio of 3HH units is less than 8 mol% is not particularly limited, and is preferably 0 to 50% by mass relative to the entire P3HB-based resin contained in the coating described above. In the case of blending, it is preferably 1 to 50% by mass, more preferably 3 to 30% by mass, further preferably 4 to 20% by mass, and particularly preferably 5 to 15% by mass.

[0049] The microorganism produces P3HB3HH as a random copolymer. The adjustment of the content ratio of 3HH units can be performed, for example, by selection of the bacterial strain, selection of the carbon source as a raw material, blending of P3HB3HH having different content ratios of 3HH units, blending of a homopolymer of 3HB, or the like.

[0050] According to one embodiment of the present application, the weight average molecular weight of the P3HB-based resin is preferably 500,000 to 6,500,000, more preferably 1,000,000 to 6,000,000, further preferably 1,500,000 to 5,500,000, and particularly preferably 1,500,000 to 5,000,000. By making the weight average molecular weight of the P3HB-based resin within the above range, the coating can exhibit a very high adhesive strength by heat sealing. Note that the weight average molecular weight of the P3HB-based resin can be obtained as the molecular weight converted to polystyrene by using polystyrene gel ("Shodex K-804" manufactured by Showa Denko K.K.) in the column and chloroform as the mobile phase by a gel permeation chromatograph (GPC) ("Shodex GPC-101" manufactured by Showa Denko K.K.).

[0051] The coating described above can contain one or two or more kinds of resins other than the P3HB-based resin within the range where the effect of the present application is exerted. As such other resins, for example, aliphatic polyester-based resins such as polybutylene succinate, 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 listed. In order to ensure the biodegradability of the coating, the amount of addition of these resins is preferably 10 parts by mass or less relative to 100 parts by mass of the P3HB-based resin. The coating described above can not contain a resin other than the P3HB-based resin.

[0052] In the range where the effect of the present application is exerted, the above-mentioned coating layer can contain additives generally used in the technical field. As such additives, for example, inorganic fillers such as talc, calcium carbonate, mica, silica, titanium oxide, aluminum oxide, etc., waste paper such as rice husks, wood powder, newspapers, etc., organic fillers such as various starches, cellulose, etc., coloring agents such as pigments, dyes, etc., odor absorbers such as activated carbon, zeolite, etc., flavorings such as vanillin, dextrin, etc., plasticizers, antioxidants, anti-oxidants, weather resistance improvers, ultraviolet absorbers, nucleating agents, lubricants, release agents, water repellents, antibacterial agents, sliding property improvers, tackifiers, fillers, medicaments, etc. can be listed. As the additives, only one kind can be contained, or two or more kinds can be contained. The content of these additives can be appropriately set by the person skilled in the art according to the purpose of use.

[0053] According to one embodiment of the present application, the above-mentioned coating layer has the following melting properties: in the crystalline melting curve obtained by differential scanning calorimetry, 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, and the temperature difference between Tma and Tmb is 10°C or more. By making the above-mentioned coating layer have such melting properties, the coating layer can be bonded by heat sealing at the time of molding of the above-mentioned laminate, and the range of applicable heat sealing temperature is large, and even if the resin is heated to a temperature at which sufficient bonding is possible, good bonding strength can be exhibited in a short time after heating.

[0054] It is presumed that by making the above-mentioned coating layer have a melting point peak in the relatively high temperature region of 150 to 170°C, the resin crystallization having Tmb functions as a crystalline nucleus, and thereby the solidification of the resin melted at the time of heat sealing is accelerated, and even if the resin is heated to a temperature at which sufficient bonding is possible, good bonding strength can be exhibited in a short time after heating.

[0055] The temperature difference between Tma and Tmb is 10°C or more, preferably 15°C or more, more preferably 20°C or more, and further preferably 25°C or more. When the above-mentioned temperature difference is less than 10°C, it is sometimes difficult to achieve the effect that even if the resin is heated to a temperature at which sufficient bonding is possible, good bonding strength can be exhibited in a short time after heating. 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.

[0056] In the present application, the peak top temperature of the crystalline melting curve in differential scanning calorimetry is defined as follows. The coating layer of 2 to 5 mg separated from the base material layer is filled into an aluminum pan, and the differential scanning calorimeter is used to melt the coating layer by raising the temperature from 20°C to 190°C at a rate of 10°C / min under a nitrogen stream, and a crystalline melting curve is obtained. 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 addition, 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. In Figure 1 In the present application, the peak top temperature of the crystalline melting curve in differential scanning calorimetry is defined as follows. The coating layer of 2 to 5 mg separated from the base material layer is filled into an aluminum pan, and the differential scanning calorimeter is used to melt the coating layer by raising the temperature from 20°C to 190°C at a rate of 10°C / min under a nitrogen stream, and a crystalline melting curve is obtained. 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 addition, 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. In

[0057] In one embodiment of the present application, in the crystalline melting curve of the above-mentioned coating layer obtained by differential scanning calorimetry, the ratio of the crystalline melting enthalpy of the peak present in the range of 100 to 150°C (ΔHa) to the crystalline melting enthalpy of the peak present in the range of 150 to 170°C (ΔHb) (ΔHb / ΔHa) is preferably 0.01 to 2. When the above-mentioned ratio is in this range, the solidification of the resin melted by heating is accelerated, and even if the resin is heated to a temperature at which sufficient adhesion is obtained, good adhesion strength is easily exhibited in a short time after heating. The above-mentioned ratio is more preferably 0.05 to 1, further preferably 0.1 to 0.8, still further preferably 0.15 to 0.6, and most preferably 0.2 to 0.4.

[0058] Note that, in the case where a plurality of melting point peaks are confirmed in the range of 100 to 150°C, the sum of the crystalline melting enthalpy of all of these melting point peaks is taken as ΔHa, and in the case where a plurality of melting point peaks are confirmed in the range of 150 to 170°C, the sum of the crystalline melting enthalpy of all of these peaks is taken as ΔHb.

[0059] The unit weight (weight per unit area) of the P3HB-based resin in the above-mentioned coating layer is preferably 5 to 100 g / m 2 , more preferably 10 to 50 g / m 2 , and particularly preferably 15 to 30 g / m 2 . When the unit weight of the P3HB-based resin in the above-mentioned coating layer is in the above-mentioned range, defects such as pores are prevented, and the strength that can withstand use can be maintained, and water resistance and the like can be exhibited with good efficiency. Note that the unit weight of the P3HB-based resin in the above-mentioned coating layer can be measured and evaluated by the method described in the examples.

[0060] The thickness of the coating layer (each coating layer in the case of the above-described laminate having two or more coating layers) is not particularly limited, and is preferably 5 to 100 μm, and more preferably 10 to 30 μm, from the viewpoint of preventing water absorption into the substrate layer and ensuring sufficient softness.

[0061] Method for manufacturing the laminate

[0062] The laminate of one embodiment of the present application can be manufactured, for example, by applying a water-based coating liquid to one side or both sides of the substrate layer, performing heating and drying and film formation. As such a method, a known method can be appropriately employed, and is not particularly limited.

[0063] The method for manufacturing the above-described laminate can include the following steps. (a) a step of manufacturing a water-based coating liquid, (b) a step of feeding the substrate layer, (c) a step of applying the above-described water-based coating liquid to the above-described substrate layer, and (d) a step of drying and film formation of the applied film.

[0064] The above-described step (a) is not particularly limited and can be performed by the following method. That is, the step (a) includes a step of separating P3HB-based resin in a microbial cell by crushing the microbial cell containing P3HB-based resin produced by a microorganism in an aqueous dispersion state.

[0065] Generally, in the recovery of P3HB-based resin from a microbial cell, a method in which P3HB-based resin is dissolved using an organic solvent such as chloroform and is precipitated and recovered using a P3HB-based resin-insoluble solvent such as methanol or hexane can be used. However, in this method, the obtained P3HB-based resin cannot be formed into fine particles, and a step of making the P3HB-based resin into fine particles needs to be added, which is disadvantageous in terms of economy. In contrast, by the step of separating P3HB-based resin in a microbial cell by crushing the microbial cell containing P3HB-based resin produced by a microorganism in an aqueous dispersion state, an aqueous dispersion liquid of P3HB-based resin fine particles in which the P3HB-based resin produced in the microbial cell is maintained in a fine particle state to a considerable extent can be obtained.

[0066] In the process of separating the P3HB-based resin in the microbial cells by crushing the microbial cells containing the P3HB-based resin in the form of an aqueous dispersion, the microbial cells containing the P3HB-based resin are preferably stirred, and crushing and alkali addition are simultaneously performed. This method has the advantages that (i) the viscosity of the dispersion can be prevented from increasing due to the components of the microbial cells other than the P3HB-based resin leaking from the microbial cells; (ii) by preventing the viscosity of the microbial cell dispersion from increasing, the pH can be controlled, and further, the treatment can be performed at a low alkali concentration by continuously or intermittently adding alkali; and (iii) the molecular weight of the P3HB-based resin can be inhibited from decreasing, and a P3HB-based resin of high purity can be separated. The pH of the microbial cell dispersion after the addition of alkali is preferably 9 to 13.5. When the pH is 9 or higher, the P3HB-based resin is easily separated from the microbial cells, and when the pH is 13.5 or lower, the decomposition of the P3HB-based resin is inhibited.

[0067] The microbial cells are crushed by a method using ultrasonic waves, a method using an emulsifying disperser, a high-pressure homogenizer, a mill, or the like. Among these, from the viewpoint that the P3HB-based resin is efficiently dissolved from the microbial cells by alkali treatment, nucleic acids, which are the main cause of the increase in viscosity, are efficiently crushed, and the cell wall, the cell membrane, insoluble proteins, and other insoluble substances other than the P3HB-based resin are sufficiently dispersed, 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. In addition, the temperature conditions for crushing the microbial cells and adding alkali are preferably in the range of room temperature to 50°C. When the above temperature conditions exceed 50°C, the decomposition of the P3HB-based resin easily occurs, and thus the temperature is preferably around room temperature. In addition, when the temperature is set to be lower than room temperature, a cooling operation is required, and thus is not economical.

[0068] The precipitate is obtained by centrifugally separating the dispersion obtained by crushing the microbial cells and performing alkali treatment, the precipitate is washed with water, and, as necessary, washed with methanol, and finally, an appropriate amount of water is added, and thus an aqueous coating solution of the P3HB-based resin containing the desired concentration of solid components can be obtained.

[0069] After the above process, a process of applying mechanical shearing to the aqueous coating liquid to separate a part of the aggregated P3HB-based resin particles from each other is preferably included. The application of mechanical shearing can obtain an aqueous coating liquid of P3HB-based resin which is substantially free of aggregates and contains uniform particle diameters, and is thus preferred from this point of view. The mechanical shearing of the aqueous coating liquid can be performed using, for example, a stirrer, a homogenizer, ultrasonic waves, or the like. At this time, the aggregation of the P3HB-based resin particles is not very strong, and thus a general stirrer equipped with a stirring blade is preferably used from the viewpoint of convenience.

[0070] The solid content concentration of the P3HB-based resin in the above aqueous coating 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 concentration of the P3HB-based resin in the above aqueous coating liquid is within the above range, the viscosity of the solution is not excessively high, and thus uniform coating can be performed, and the desired film thickness can be maintained, and thus the effect of not easily causing film defects can be exhibited.

[0071] 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 coating 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. Note that the average particle diameter of the P3HB-based resin in the aqueous coating liquid can be calculated by adjusting a water suspension containing the P3HB-based resin to a given concentration using a general particle size meter such as a MICROTRAC particle size meter (manufactured by NIKKISO CO., LTD., FRA), and measuring the particle diameter corresponding to 50% of the cumulative amount of all particles in a normal distribution.

[0072] The above aqueous coating liquid can be free of an emulsifier, and an emulsifier is preferably included in order to stabilize the coating liquid. As the emulsifier, for example, 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, water-soluble polymers such as polyvinyl alcohol and polyvinylpyrrolidone, and the like can be listed. The amount of the emulsifier to be added is not particularly limited, and is preferably 1 to 10% by weight relative to the solid content of the P3HB-based resin. When the amount of the emulsifier to be added is 1% by weight or more, the tendency to obtain the stabilization effect due to the emulsifier is high, and when the amount is 10% by weight or less, the decrease in properties and coloring of the P3HB-based resin due to the mixing of an excessive amount of the emulsifier can be avoided.

[0073] The above-mentioned emulsifier can be added to the aqueous dispersion after centrifugal separation and water washing after the microbial cell is broken and treated with alkali. In the case where methanol washing is performed, the emulsifier can be added after methanol washing and before or after the solid content concentration of the P3HB-based resin is adjusted by adding an appropriate amount of water.

[0074] The above-mentioned processes (b) and (c) are not particularly limited and can be performed by any method known in the art.

[0075] In one embodiment of the present application, the heating temperature in the drying and film-forming process of the coated film in the above-mentioned process (d) is preferably 130 to 170°C, more preferably 135 to 165°C, further preferably 138 to 162°C, particularly preferably 140 to 160°C. By heating and drying and film-forming the coated film at such a temperature, a coating layer showing the above-mentioned melting property can be formed to obtain the above-mentioned laminate.

[0076] The heating time in the drying and film-forming process of the coated film in the above-mentioned process (d) is not particularly limited and can be appropriately set, for example, it can be 30 seconds to 10 minutes, preferably 1 to 5 minutes.

[0077] The manufacturing method of the above-mentioned laminate can include a process (e) of winding the laminate after the above-mentioned process (d). The above-mentioned process (e) is not particularly limited and can be performed by any method known in the art.

[0078] [Shaped Body]

[0079] The shaped body of one embodiment of the present application contains the above-mentioned laminate. The above-mentioned shaped body can be bonded by heat sealing at the time of 2-step processing of the above-mentioned laminate, and the range of applicable heat sealing temperature is large, and even if the resin is heated to a temperature at which sufficient bonding can be achieved, good bonding strength can be exhibited in a short time after heating. Since the laminate is contained, the cycle time of heat sealing can be shortened and the production efficiency of the shaped body can be improved.

[0080] The above-mentioned shaped body is not particularly limited as long as it contains the above-mentioned laminate, and examples thereof include paper, film, sheet, tube, plate, rod, packaging material (for example, bag), container (for example, bottle container), member, and the like. From the viewpoint of measures against marine pollution, the above-mentioned shaped body is preferably a packaging material or a container.

[0081] In one embodiment of the present application, the above-mentioned shaped body can be the above-mentioned laminate itself. In addition, in one embodiment of the present application, the above-mentioned laminate contained in the above-mentioned shaped body can be a laminate subjected to 2-step processing.

[0082] The above-described laminate is processed twice, and the above-described molded body containing the same can be preferably used as a shopping bag, various bag-making, a packaging material for food / snacks, a cup, a tray, a carton, and the like, various packaging container materials (in other words, for various fields of food, cosmetics, electronics, medical care, pharmaceuticals, and the like). The above-described laminate contains a coating layer having high adhesion to a base material and good heat resistance, and thus the above-described laminate can be particularly preferably used as a container for containing a warm content, such as a container for a beverage food cup for instant noodles, instant soup, coffee, and the like, a tray for a vegetarian dish, a bento, a microwave oven food, and the like.

[0083] The above-described processing twice can be performed using any method known in the technical field, such as various bag-making machines, filling and packaging machines, and the like. In addition, the processing can be performed using a paper cup forming machine, a blanking machine, a box-making machine, and the like. In these processing machines, the adhesion method of the laminate can use known techniques, and for example, 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 can be used. In particular, the above-described molded body is preferably a molded body processed twice using a heat sealing method, that is, preferably contains a heat-sealed portion based on the coating layer. The heat sealing can be performed between the base material layer and the coating layer, or between the coating layers.

[0084] The heat sealing temperature at the time of heat sealing of the above-described laminate differs depending on the adhesion method, the base material, and the thickness of the coating film. In the case of heat sealing of the coating layers of the above-described laminate to each other using a heating-type heat sealing tester having a sealing bar with both sides heated, the heat sealing temperature is generally 250°C or lower, preferably 240°C or lower, and more preferably 220°C or lower. When in the above-described range, the elution of the resin near the sealing portion can be avoided, and an appropriate film thickness of the coating layer and a sealing strength can be ensured. In addition, the lower limit value of the heat sealing temperature when using a heating-type heat sealing tester having a sealing bar is generally 120°C or higher, and preferably 140°C or higher. When in the above-described range, appropriate adhesion of the sealing portion can be ensured. In addition, the heat sealing temperature of the laminate of one embodiment of the present application can exhibit good adhesion strength in a short time after heat sealing even if it is a high temperature, and thus the heat sealing temperature can be 180°C or higher, and can be 200°C or higher. According to a particularly preferable mode, the heat sealing temperature can be 220°C or higher.

[0085] The heat seal temperature when heat-sealing the coating of the above-described laminate with paper as a base material is, in the case of two-sided heating using a heat seal tester with a seal bar, generally 250°C or lower, preferably 240°C or lower, and more preferably 220°C or lower. When within the above-described range, the elution of the resin near the seal portion can be avoided, and an appropriate film thickness of the coating and seal strength can be ensured. In addition, the lower limit of the heat seal temperature when using a heat seal tester with a seal bar is generally 120°C or higher, and preferably 140°C or higher. When within the above-described range, appropriate adhesion of the seal portion can be ensured. In addition, the heat seal temperature of the laminate of one embodiment of the present application can exhibit good adhesion strength in a short time after heat-sealing even at a high temperature, and thus the heat seal temperature can be 170°C or higher, and can be 180°C or higher. According to a particularly preferred embodiment, the heat seal temperature can be 190°C or higher.

[0086] The heat seal pressure when heat-sealing the above-described laminate differs depending on the adhesion method. The heat seal pressure of the above-described laminate is, in the case of using a heat seal tester with a seal bar, generally 0.1 MPa or higher, and preferably 0.3 MPa or higher. When within the above-described range, appropriate adhesion of the seal portion can be ensured.

[0087] The molded body of one embodiment of the present application can also be complexed with another molded body (e.g., a fiber, a filament, a cord, a fabric, a knitted fabric, a nonwoven fabric, paper, a film, a sheet, a tube, a plate, a rod, a container, a bag, a member, a foam, or 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.

[0088] Examples

[0089] Hereinafter, the present application will be specifically described by examples, but the technical scope of the present application is not limited by these examples.

[0090] (Release test)

[0091] Each coated paper was cut to a width of 25 mm. The coating of the coated paper was heat-sealed to each other or to the paper using a heat sealer (TP-701-B, TESTER SANGYO Co., Ltd.) under conditions of a heating temperature of 120°C, 140°C, 160°C, 170°C, 180°C, 190°C, 200°C, or 220°C, a face pressure of 0.4 MPa, and a seal time of 1 second, and after 2 seconds from the time when the heat seal bar was separated from the coated paper, the seal surface was peeled by hand. The peeled surface was observed with the naked eye, and evaluated in accordance with the following criteria.

[0092] < Evaluation >

[0093] O: The paper was damaged in material

[0094] Δ: A part of the paper has material damage

[0095] X: The paper has no material damage

[0096] (unit area weight of resin component)

[0097] Each coated paper was cut into 10 cm x 10 cm, and the weight was measured, and the weight of the base paper was subtracted therefrom, and the value of 100 times was taken as the unit area weight value of the resin component.

[0098] [Manufacturing Example]

[0099] (manufacturing method of resin dispersion liquid)

[0100] A resin dispersion liquid having a solid component concentration of 50% by weight of P3HB3HH was obtained according to the method described in International Publication No. 2015 / 1461965.

[0101] (manufacturing method of aqueous coating liquid)

[0102] An aqueous coating liquid was obtained by adding a 2% aqueous solution so that the amount of methylcellulose (METOLOSE SM-400, manufactured by Shin-Etsu Chemical Co., Ltd.) was 1 part by weight with respect to 100 parts by weight of the resin contained in the resin dispersion liquid, and stirring was performed.

[0103] [Example 1]

[0104] An aqueous dispersion liquid of P3HB3HH having a content ratio of 11 mol% and a weight average molecular weight of 260,000 of 3-hydroxyhexanoate units was used to manufacture an aqueous coating liquid. After the aqueous coating liquid was applied to a base paper of A3 size having a unit area weight of 200 g / m 2 using a slot coater with an application thickness of 90 μm, and heating in an oven at 160°C for 3 minutes, a coating layer was formed. The unit area weight of the resin component was 20 g / m 2 A peeling test was performed on the obtained coated paper.

[0105] [Example 2]

[0106] An aqueous dispersion liquid of P3HB3HH having a content ratio of 0.7 mol% and a weight average molecular weight of 350,000 of 3-hydroxyhexanoate units was blended in a manner of 10% by weight based on the resin matrix in an aqueous dispersion liquid of P3HB3HH having a content ratio of 11 mol% and a weight average molecular weight of 260,000 of 3-hydroxyhexanoate units. An aqueous coating liquid was manufactured using the blended aqueous dispersion liquid. After the aqueous coating liquid was applied to a base paper of A3 size having a unit area weight of 200 g / m 2After applying an aqueous coating solution to A3-sized base paper, the paper was heated in an oven at 160℃ for 3 minutes to form a coating. The resin component has a unit area weight of 20 g / m². 2 Peel tests were conducted on the obtained coated paper.

[0107] [Example 3]

[0108] An aqueous dispersion of P3HB3HH containing 0.7 mol% of 3-hydroxyhexanoate units and with a weight-average molecular weight of 350,000 was blended with 5 wt% of P3HB3HH containing 3-hydroxyhexanoate units at a ratio of 11 mol% to 260,000 wt% based on the resin matrix. An aqueous coating liquid was prepared using the blended aqueous dispersion. A slot coater with a coating thickness of 90 μm was used to achieve a coating thickness of 200 g / m². 2 After applying an aqueous coating solution to A3-sized base paper, the paper was heated in an oven at 160℃ for 3 minutes to form a coating. The resin component has a unit area weight of 20 g / m². 2 Peel tests were conducted on the obtained coated paper.

[0109] [Example 4]

[0110] An aqueous dispersion of P3HB3HH containing 11 mol% of 3-hydroxyhexanoate units and with a weight-average molecular weight of 260,000 was blended with 20 wt% of P3HB3HH containing 0.7 mol% of 3-hydroxyhexanoate units and with a weight-average molecular weight of 350,000, based on the resin matrix. An aqueous coating liquid was prepared using the blended aqueous dispersion. A slot coater with a coating thickness of 90 μm was used to achieve a coating thickness of 200 g / m². 2 After applying an aqueous coating solution to A3-sized base paper, the paper was heated in an oven at 160℃ for 3 minutes to form a coating. The resin component has a unit area weight of 20 g / m². 2 Peel tests were conducted on the obtained coated paper.

[0111] [Comparative Example 1]

[0112] An aqueous coating solution was obtained using an aqueous dispersion of P3HB3HH containing 6 mol% of 3-hydroxyhexanoate units and a weight-average molecular weight of 250,000. A slot coater with a coating thickness of 90 μm and a unit area weight of 200 g / m² was used. 2 After applying an aqueous coating solution to A3-sized base paper, the paper was heated in an oven at 160℃ for 3 minutes to form a coating. The resin component has a unit area weight of 20 g / m². 2 Peel tests were conducted on the obtained coated paper.

[0113] (Differential Scanning Calorimetry)

[0114] The aqueous coating solution used in Examples 1 to 4 and Comparative Example 1 was applied to a PET film using a slit coater with a coating thickness of 90 μm, and heated at 160°C for 3 minutes to form a coating layer. The coating layer was peeled from the PET film and subjected to the following differential scanning calorimetry.

[0115] 2 to 5 mg of the coating layer was filled in an aluminum pan, and a differential scanning calorimeter was used to raise the temperature from 20°C to 190°C at a rate of 10°C / min under a nitrogen stream to melt the coating layer, and a crystalline melting curve was obtained.

[0116] In the obtained crystalline melting curve, the peak top temperature of the melting point peak present in the range of 100 to 150°C was taken as Tma, and the crystalline melting enthalpy of the peak was taken as ΔHa. In the case where a plurality of melting point peaks were confirmed in the range of 100 to 150°C, the melting point temperature of the peak with the highest height was taken as Tma, and the total value of the crystalline melting enthalpy of each peak was taken as ΔHa.

[0117] In addition, the peak top temperature of the melting point peak present in the range of 150 to 170°C was taken as Tmb, and the crystalline melting enthalpy of the peak was taken as ΔHb. In the case where a plurality of melting point peaks were confirmed in the range of 150 to 170°C, the melting point temperature of the peak with the highest height was taken as Tmb, and the total value of the crystalline melting enthalpy of each peak was taken as ΔHb.

[0118] [Results]

[0119] Figure 1 The crystalline melting curve obtained by differential scanning calorimetry measured for Example 1 is shown in FIG. 1. The Tmaof the coating layer of Example 1 was 120°C, and the Tmbwas 154°C.

[0120] The Tmaof the coating layer of Example 2 was 120°C, and the Tmbwas 152°C.

[0121] The Tmaof the coating layer of Example 3 was 120°C, and the Tmbwas 165°C.

[0122] The Tmaof the coating layer of Example 4 was 120°C, and the Tmbwas 165°C.

[0123] The Tmaof the coating layer of Comparative Example 1 was 145°C, and no melting point peak was present in the range of 150 to 170°C.

[0124] Table 1 shows the results of the peeling test after heat sealing for 2 seconds and the values of Tma, Tmb, and ΔHb / Δhaof Examples 1 and 2 and Comparative Example 1 when the coating layers were pressed against each other. Table 2 shows the results of the peeling test after heat sealing for 2 seconds and the values of Tma, Tmb, and ΔHb / Δhaof Examples 1 to 4 and Comparative Example 1 when the coating layers were pressed against paper.

[0125] Table 1

[0126]

[0127] [Table 2]

[0128]

[0129] In Example 1, in the peeling test after heat sealing for 2 seconds, in the case where the coating layers were pressed against each other (Table 1), the heating temperature at the time of heat sealing was a wide range of 120 to 200°C, and in the case where the coating layer was pressed against paper (Table 2), the heating temperature at the time of heat sealing was a wide range of 140 to 180°C, and the paper was subjected to material destruction. That is, it was shown that, in these temperature ranges, the molten resin was solidified after heat sealing for 2 seconds, and exhibited good adhesive strength.

[0130] In Comparative Example 1, in the peeling test after heat sealing for 2 seconds, in the case where the coating layers were pressed against each other, the heating temperature at the time of heat sealing was a range of 140 to 160°C, and in the case where the coating layer was pressed against paper, the heating temperature at the time of heat sealing was 180°C, and although the paper was subjected to material destruction, the paper was not subjected to material destruction at temperatures other than the above, and it was shown that the molten resin was not sufficiently solidified.

[0131] The Tma value and the Tmb value of the coating layers of Examples 2 to 4 did not greatly change from Example 1, but the value of ΔHb / Δha was 0.25 to 0.51, which showed a larger value than 0.12 of Example 1. In the peeling test after heat sealing for 2 seconds, the heating temperature at the time of heat sealing was 220°C (Table 1) or 190°C (Table 2), and the paper was subjected to material destruction, and at a higher temperature than Example 1, the solidification of the resin immediately after heat sealing also rapidly proceeded, and good adhesive strength could be exhibited.

[0132] In summary, even if Example 1 was subjected to heat sealing at a lower temperature than Comparative Example 1, good adhesive strength was exhibited in a short time. Furthermore, Examples 2 to 4 were also subjected to heat sealing at a higher temperature than Example 1, and good adhesive strength was exhibited in a short time. It can be considered that this effect is due to the fact that, in the coating layer having a melting point peak within 150 to 170°C in addition to the melting point peak within 100 to 150°C as in Examples 1 to 4, the resin crystallized within 150 to 170°C functions as a nucleus, and thus the solidification of the molten resin is accelerated. Furthermore, it can be considered that the degree of improvement in the solidification speed is proportional to the value of ΔHb / Δha.

[0133] However, in Example 4 in which the addition amount of P3HB3HH having a content ratio of 3-hydroxyhexanoate units of 0.7 mol% was 20% by weight, although the curability increased, the area of paper peeling decreased. It can be presumed that this was caused by the fact that the melt tension of the resin increased, and the penetration into the paper deteriorated. Therefore, from the viewpoint of ensuring the strength of the laminate, it is preferable to adjust the compounding amount of P3HB3HH or P3HB in which the content ratio of 3HH units is less than 8 mol%.

Claims

1. A laminate having a substrate layer and a coating layer laminated on at least one side of the substrate layer, wherein, The substrate layer is paper. The coating comprises a poly(3-hydroxybutyrate) resin. In the crystallization melting curve obtained by differential scanning calorimetry, the coating has at least one peak temperature (Tma) in the range of 100–150 °C and at least one peak temperature (Tmb) in the range of 150–170 °C, and the temperature difference between Tma and Tmb is greater than 10 °C. The poly(3-hydroxybutyrate) resin comprises: The 3-hydroxyhexanoate unit contains 8 mol% or more and 25 mol% of poly(3-hydroxybutyrate-copolymer-3-hydroxyhexanoate), and The 3-hydroxyhexanoate unit comprises a poly(3-hydroxybutyrate-copolymer-3-hydroxyhexanoate) containing 0.1 mol% to 1 mol% of the poly(3-hydroxybutyrate-copolymer-3-hydroxyhexanoate). Compared to the coating containing the poly(3-hydroxybutyrate) resin as a whole, The content of poly(3-hydroxybutyrate-copolymer-3-hydroxyhexanoate) in the 3-hydroxyhexanoate unit is 5 to 15% by weight, with a content of 0.1 mol% or more and 1 mol% or less.

2. The laminated body according to claim 1, wherein, In the crystallization melting curve of the coating obtained by differential scanning calorimetry, the ratio (ΔHb / ΔHa) of the enthalpy of crystallization melting of the peak located in the range of 100 to 150 °C to the enthalpy of crystallization melting of the peak located in the range of 150 to 170 °C is 0.01 to 2.

3. The laminate according to claim 1 or 2, wherein, The weight-average molecular weight of the poly(3-hydroxybutyrate) resin is 50,000 to 650,000.

4. A method for manufacturing a laminate according to any one of claims 1 to 3, the method comprising: The process of applying an aqueous coating solution containing the poly(3-hydroxybutyrate) resin to a substrate to form a coating film, and The process of forming the coating by heating the coating film at a temperature of 130°C or higher and 170°C or lower.

5. A molded body comprising the laminated body according to any one of claims 1 to 3.

6. A method for manufacturing the molded article of claim 5, the method comprising: The process of heat-sealing the coating.

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