Biodegradable polyester solution and its use

Abstract

To provide a biodegradable polyester solution that contains a non-halogen-based organic solvent showing good solubility in polyhydroxyalkanoate resin, has low environmental load, and has excellent secondary processability.SOLUTION: Provided is a biodegradable polyester solution, which is a biodegradable polyester solution that contains poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer and non-halogen-based organic solvent, and in which the average content ratio of 3-hydroxyhexanoate in the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer is less than 16 mol%, and the non-halogen-based organic solvent is at least one selected from the group of organic solvents having 3 to 6 carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a biodegradable polyester solution and its use. [Background technology]

[0002] A large amount of petroleum-derived plastics is discarded every year, and the resulting lack of landfill sites and environmental pollution are becoming serious issues. In recent years, microplastics derived from these wastes have become a major problem in the marine environment.

[0003] Polyhydroxyalkanoate resins have excellent seawater degradability and are therefore attracting attention as materials that can solve environmental problems caused by discarded plastics. When polyhydroxyalkanoate resins are subjected to secondary processing, adhesives, inks, coating agents, etc. (also referred to as "secondary processing components") are sometimes used, and from the perspective of the above-mentioned environmental issues, the secondary processing components are also required to be seawater degradable. As an example of a secondary processing member that is decomposable in seawater, Patent Document 1 discloses that a solution is prepared by dissolving a polyhydroxyalkanoate resin in an organic solvent, and a film is produced from the resulting solution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-62343 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the solution in Patent Document 1 uses a halogenated solvent, and since the use of halogenated solvents raises concerns that they may pollute the environment if they leak out of the system, they must be used under strict control, and there has been a demand for the use of non-halogenated solvents in consideration of the environment. Furthermore, halogen-based solvents tend to be highly volatile, evaporating rapidly during secondary processing and causing condensation and other problems that can lead to poor appearance in the secondary processed products, making it necessary to take measures such as strictly controlling humidity and temperature.

[0006] Therefore, an object of the present invention is to provide a biodegradable polyester solution containing a non-halogenated organic solvent that exhibits good solubility for polyhydroxyalkanoate resin, which has a low environmental impact, and is excellent in secondary processability. [Means for solving the problem]

[0007] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that by dissolving poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer (hereinafter referred to as "PHBH") having an average content ratio of 3-hydroxyhexanoate (hereinafter referred to as 3HH) within a specific range in a specific non-halogenated organic solvent, a biodegradable polyester solution containing the PHBH has low environmental impact and excellent secondary processability, and have completed the present invention.

[0008] That is, the present invention provides a biodegradable polyester solution containing poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer and a non-halogen-based organic solvent, the average content of 3-hydroxyhexanoate in the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer is less than 16 mol%, The present invention relates to a biodegradable polyester solution, wherein the non-halogen organic solvent is at least one selected from the group consisting of organic solvents having 3 to 6 carbon atoms. Preferably, the non-halogenated organic solvent is an organic solvent having a boiling point of 60° C. or higher. Preferably, the composition is substantially free of insoluble matter derived from the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer. Preferably, the organic solvent is at least one selected from the group consisting of aliphatic ether solvents, aliphatic ester solvents, and aliphatic ketone solvents. Preferably, the organic solvent is at least one selected from the group consisting of tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, ethyl acetate, butyl acetate, isobutyl acetate, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone. Preferably, the solid content concentration of the copolymer in the biodegradable polyester solution is 0.01 to 15% by weight. Preferably, the average content of 3-hydroxyhexanoate in the copolymer is 10 mol % or more and less than 16 mol %. The present invention also relates to a biodegradable adhesive containing the biodegradable polyester solution. The present invention also relates to a biodegradable ink containing the biodegradable polyester solution and a pigment and / or a dye. The present invention also relates to a coating material comprising a substrate and a resin layer on at least a portion of the surface of the substrate, wherein the resin layer is formed by applying the biodegradable polyester solution to the substrate. The present invention further relates to a biodegradable laminate comprising a biodegradable substrate and a resin layer on at least one surface of the biodegradable substrate, the resin layer being formed by applying the biodegradable polyester solution to the biodegradable substrate. Preferably, the biodegradable substrate is paper or a biodegradable polyester. The present invention also relates to a method for producing a biodegradable laminate including a biodegradable substrate and a resin layer, the method including a coating step of applying the biodegradable polyester solution to at least one surface of the biodegradable substrate to form the resin layer. The biodegradable substrate is paper or biodegradable polyester. [Effects of the Invention]

[0009] According to one aspect of the present invention, a biodegradable polyester solution can be provided which contains a non-halogenated organic solvent that exhibits good solubility for polyhydroxyalkanoate resin, has low environmental impact, and is excellent in secondary processability. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described in detail below. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less."

[0011] 1. Overview of the Invention A biodegradable polyester solution according to one embodiment of the present invention (hereinafter referred to as "the present biodegradable polyester solution") is a biodegradable polyester solution containing a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer and a non-halogenated organic solvent, characterized in that the average content of 3-hydroxyhexanoate in the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer is less than 16 mol%, and the non-halogenated organic solvent is at least one selected from the group of organic solvents having 3 to 6 carbon atoms.

[0012] The present inventors focused on PHBH as a resin that is degradable in seawater and investigated technologies related to polyester solutions containing PHBH. They found that, although PHBH is generally poorly soluble in organic solvents, it is slightly soluble in halogenated organic solvents such as chloroform. However, halogenated organic solvents not only pose problems in terms of the working environment and human health, but also have relatively high volatility. During secondary processing such as coating, the solvent rapidly evaporates during coating, causing moisture in the air to condense on the surface of the coating film and precipitate solids derived from the copolymer, thereby deteriorating the appearance and properties of the secondary processed product.

[0013] Therefore, the inventors further investigated and found that a specific non-halogenated organic solvent can dissolve PHBH, and that the resulting PHBH-containing solution is less likely to cause the above-mentioned problems during secondary processing due to the properties of the organic solvent contained therein. Furthermore, the inventors found that the PHBH used has an HH ratio of less than 16 mol%, and that the crystallization (solidification) after removing the solvent by drying is good, resulting in excellent processability after secondary processing (e.g., laminate).

[0014] [2. Biodegradable polyester solution] (PHBH) PHBH is a copolymer of 3-hydroxybutyrate (also referred to as "3HB") and 3HH repeating units.

[0015] In one embodiment of the present invention, PHBH may be obtained by either a method of producing it from a microorganism or a chemical synthesis method, and is not particularly limited. Among these, PHBH obtained by a method of producing it from a microorganism is preferred because it is in the form of fine particles.

[0016] Microorganisms that produce PHBH are not particularly limited as long as they are capable of intracellularly accumulating PHBH. Examples include bacteria of the genus Alcaligenes, such as Alcaligenes lipolytica, Alcaligenes eutrophus, and Alcaligenes latus, as well as bacteria of the genus Pseudomonas, Bacillus, Azotobacter, Nocardia, and Aeromonas. Among these, strains such as Aeromonas caviae are particularly preferred in terms of PHBH productivity, and Alcaligenes eutrophus AC32 strain (accession number FERM BP-6038 (transferred from the original deposit (FERM P-15786) deposited on August 12, 1996) (August 7, 1997, National Institute of Advanced Industrial Science and Technology, International Patent Organism Depositary, address: Central 6, 1-1 Higashi 1-chome, Tsukuba, Ibaraki Prefecture, Japan)) (J. Bacteriol., 179, pp. 4821-4830 (1997)) into which genes encoding PHA synthases have been introduced is more preferred. A method for obtaining PHBH from Aeromonas caviae, a microorganism of the genus Aeromonas, is disclosed, for example, in Japanese Patent Application Laid-Open No. 5-93049. These microorganisms are used by culturing them under appropriate conditions to allow PHBH to accumulate in the cells.

[0017] The carbon source and culture conditions used for the culture may be in accordance with, for example, the methods described in Japanese Patent Application Laid-Open Nos. 5-93049 and 2001-340078, but are not limited thereto.

[0018] The microbially produced PHBH obtained by the above method is a random copolymer. The 3HH content (composition) can be adjusted by, for example, selecting the bacterial cells, selecting the carbon source as the raw material, blending PHBHs with different 3HH compositions, blending 3HB homopolymers, etc. Examples include a method in which PHBH produced by bacterial cells is used as is, or a method in which PHBHs produced by multiple bacterial cells are mixed so that the average 3HH content in the PHBH falls within the specified range of the present invention.

[0019] The average content of 3HH in PHBH is less than 16 mol%, preferably 14 mol% or less, and more preferably 12 mol% or less. When the average content of 3HH in PHBH is less than 16 mol%, an excellent balance is achieved between solubility in non-halogenated organic solvents and solidification during secondary processing or when the secondary processed product is further processed. When the content is 16 mol or more, although solubility in solvents is excellent, solidification tends to be slow and tackiness tends to remain.

[0020] The lower limit of the average content of 3HH in PHBH is not particularly limited, but from the viewpoint of solubility, it is preferably 1 mol% or more, more preferably 5 mol% or more, and particularly preferably 10 mol% or more. The average content of each monomer unit in all monomer units constituting PHBH can be determined by a method known to those skilled in the art, for example, the method described in paragraph

[0047] of WO 2013 / 147139. The average content refers to the molar ratio of each monomer unit in all monomer units constituting the poly(3-hydroxybutyrate)-based resin. When PHBH is a mixture of two or more types of PHBH, it refers to the molar ratio of each monomer unit contained in the entire mixture.

[0021] In one embodiment of the present invention, the weight-average molecular weight (g / mol) of PHBH in the biodegradable polyester solution is, for example, 100,000 to 3,000,000, preferably 150,000 to 2,500,000, more preferably 200,000 to 2,300,000, and particularly preferably 300,000 to 2,100,000. When the weight-average molecular weight of PHBH is 50,000 or more, it exhibits the effect of exhibiting good adhesive strength. When the weight-average molecular weight of PHBH is 3,000,000 or less, it exhibits the effect of dissolving in a non-halogenated organic solvent in a short time. The weight-average molecular weight of PHBH in the biodegradable polyester solution can be determined as the molecular weight in terms of polystyrene by gel permeation chromatography (GPC) (Shodex GPC-101, manufactured by Showa Denko K.K.) using a polystyrene gel (Shodex K-804, manufactured by Showa Denko K.K.) as a column and chloroform as the mobile phase.

[0022] The biodegradable polyester solution may contain insoluble components of the copolymer as long as a transparent coating film or film can be obtained as a secondary processed product, but it is preferable that the solution is substantially free of insoluble components in order to obtain a better appearance of the coating film, film, etc. after secondary processing. In the present invention, "substantially free of insoluble components" refers to, for example, a state in which no solid components derived from the copolymer are visually observed.

[0023] (organic solvent) In this specification, the "non-halogen-based organic solvent" having 3 to 6 carbon atoms is not particularly limited as long as it can dissolve PHBH well, and examples thereof include aliphatic ether-based solvents, aliphatic ester-based solvents, aliphatic ketone-based solvents, and aromatic solvents. As the aliphatic ether, an aliphatic cyclic ether can be preferably used in terms of solubility.

[0024] From the viewpoint of workability during secondary processing, such as good solubility with PHBH and fast drying speed, preferred are aliphatic cyclic ether solvents such as tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and 1,3,5-trioxane; aliphatic ester solvents such as ethyl acetate, butyl acetate, and isobutyl acetate; and aliphatic ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone. Butyl acetate, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane are particularly preferred. The above organic solvents may be used alone or in combination of two or more.

[0025] The boiling point of the non-halogenated organic solvent according to the present invention is not particularly limited as long as the solvent can be distilled off by heating or the like, but from the viewpoint of workability (volatility) during secondary processing, it is preferably 60° C. or higher, more preferably 65° C. or higher, and particularly preferably 70° C. or higher. The upper limit of the boiling point of the non-halogenated organic solvent is not particularly limited, but from the viewpoint of ease of drying by heating, it is preferably 130° C. or lower, more preferably 120° C. or lower, and particularly preferably 110° C. or lower. The non-halogenated organic solvent according to the present invention has a carbon number of 3 to 6, but an organic solvent having a carbon number of 4 or 5 is particularly preferred in terms of the balance between volatility, drying property, and solubility. If the non-halogenated organic solvent has a carbon number of less than 3, it will be too volatile, and for example, when coating as a secondary process, condensation may cause the appearance of the coating surface to deteriorate, or PHBH may precipitate in the coating device, resulting in an unstable coating. If the non-halogenated organic solvent according to the present invention has a carbon number of more than 6, the drying property and solubility of PHBH tend to be reduced.

[0026] (biodegradable polyester solution) As used herein, the term "biodegradable polyester solution" refers to a solution containing a polyester that can be decomposed by microorganisms in soil and / or seawater. The biodegradable polyester solution contains at least PHBH as the biodegradable polyester.

[0027] In one embodiment of the present invention, the solids concentration of PHBH in the biodegradable polyester solution is, for example, preferably 0.01 to 15 wt %, more preferably 0.015 to 10 wt %, particularly preferably 0.02 to 5 wt %, and even more preferably 0.025 to 2.5 wt % in terms of workability during secondary processing. When the solids concentration of PHBH is in the range of 0.01 to 15 wt %, the effect of having a viscosity suitable for processing is achieved. The solids concentration of PHBH in the biodegradable polyester solution is the solids concentration at 60°C and is measured by the method described in the Examples.

[0028] In one embodiment of the present invention, the biodegradable polyester solution may contain one or more biodegradable resins other than PHBH, as long as the effects of the present invention are achieved. Examples of such other resins include aliphatic polyester resins such as polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate, polybutylene sebacate terephthalate, and polybutylene azelate terephthalate. The amount of these resins added is preferably 30 parts by weight or less per 100 parts by weight of PHBH to ensure the biodegradability of the biodegradable polyester solution.

[0029] In one embodiment of the present invention, the biodegradable polyester solution may contain additives commonly used in the art, as long as the effects of the present invention are achieved. Examples of such additives include inorganic fillers such as talc, calcium carbonate, mica, silica, titanium oxide, and alumina; organic fillers such as rice husk, wood flour, and recycled paper such as newspaper; various starches and cellulose; colorants such as pigments and dyes; odor absorbers such as activated carbon and zeolite; fragrances such as vanillin and dextrin; plasticizers; antioxidants; weather resistance improvers; UV absorbers; nucleating agents; lubricants; release agents; water repellents; antibacterial agents; sliding property improvers; tackifiers; fillers; and chemicals. The biodegradable polyester solution may contain one type of additive or two or more types of additives. The solids concentration of the additive can be appropriately determined by those skilled in the art depending on the intended use.

[0030] [2.Applications] As described above, the biodegradable polyester solution exhibits good solubility in non-halogenated organic solvents and excellent secondary processability, making it suitable for a variety of applications. Examples of such applications include, but are not limited to, adhesives, pressure-sensitive adhesives, inks, coating agents, binders, etc. Below, adhesives and inks are described in detail as representative examples.

[0031] (biodegradable adhesive) In one embodiment of the present invention, a biodegradable adhesive containing the biodegradable polyester solution (hereinafter referred to as the "biodegradable adhesive") is provided. The biodegradable adhesive exhibits good solubility in non-halogenated organic solvents and has excellent secondary processability, making it less problematic in the working environment and for human health, and more useful than conventional adhesives.

[0032] The solid content concentration of PHBH in the biodegradable adhesive is not particularly limited, but is, for example, preferably 0.01 to 15 wt%, more preferably 0.015 to 10 wt%, particularly preferably 0.02 to 5 wt%, and even more preferably 0.025 to 2.5 wt%. When the solid content concentration of PHBH is in the range of 0.01 to 15 wt%, the adhesive has an effect of having a viscosity suitable for application.

[0033] In one embodiment of the present invention, the biodegradable adhesive may contain various substances that can be added to conventional adhesives, as long as the biodegradability is not impaired. Examples of such additives include colorants, fillers, plasticizers, extenders, resins, etc. The biodegradable adhesive may contain only one type of additive, or two or more types. Furthermore, the solids concentration of the additive can be appropriately determined by those skilled in the art depending on the intended use.

[0034] (biodegradable ink) In one embodiment of the present invention, a biodegradable ink (hereinafter referred to as "the present biodegradable ink") containing the present biodegradable polyester solution and a pigment and / or dye is provided. The present biodegradable ink contains a biodegradable polyester solution that exhibits good solubility in non-halogenated organic solvents and has sufficient adhesive strength even after short-term aging, and therefore poses fewer problems to the working environment and human health, making it more useful than conventional inks.

[0035] The solids concentration of PHBH in the biodegradable ink is not particularly limited, but is preferably 0.01 to 15 wt%, more preferably 0.015 to 10 wt%, particularly preferably 0.02 to 5 wt%, and even more preferably 0.025 to 2.5 wt%. When the solids concentration of PHBH is in the range of 0.01 to 15 wt%, the ink has a viscosity suitable for application.

[0036] The pigment contained in the biodegradable ink is not particularly limited, but examples thereof include titanium oxide, calcium carbonate, barium sulfate, yellow iron oxide, carbon black, aluminum powder, mica, titanium powder, etc. These can be used alone or in combination of two or more. The dye contained in the biodegradable ink is not particularly limited, but examples of the dye include acid dyes, basic dyes, direct dyes, reactive dyes, disperse dyes, and metal-containing dyes. Coloring materials such as pigments and dyes can be used alone or in combination of two or more.

[0037] The solids concentration of the pigment and / or dye in the biodegradable ink (% by weight of pigment / dye relative to the sum of the weight of pigment / dye and the weight of the solvent) is not particularly limited, but is, for example, 0.1 to 20% by weight, preferably 0.2 to 15% by weight, and more preferably 0.3 to 10% by weight. If the solids concentration of the pigment and / or dye is 0.1% by weight or more, a good coloring effect is achieved. If the solids concentration of the pigment and / or dye is 20% by weight or less, the effect of achieving a viscosity suitable for application is achieved.

[0038] In one embodiment of the present invention, the biodegradable ink may contain, in addition to the pigments and / or dyes described above, various substances that can be added to conventional inks, provided that the biodegradability is not impaired. Examples of such additives include dispersants, surfactants, anti-friction agents, anti-mold agents, preservatives, antioxidants, thickening stabilizers, and gloss agents. The ink may contain one type of additive or two or more types. Furthermore, the solids concentration of the additives can be appropriately determined by those skilled in the art depending on the intended use.

[0039] (covering material) In one embodiment of the present invention, a coating material can be provided in which the present biodegradable ester solution is applied (coated) to at least a portion of the surface of a substrate to form a biodegradable polyester resin layer on that portion of the substrate surface. The coating method is not particularly limited as long as it can form a biodegradable polyester resin layer by removing the solvent from the solution. For example, immersion, brush coating, spray coating, and coating methods using various coaters can be used. The present biodegradable polyester solution can also be applied by pouring it over the substrate. The shape of the substrate is not particularly limited, but it may be flat, spherical, or the like.

[0040] (biodegradable laminate) In one embodiment of the present invention, as one form of the above-mentioned dressing material, there is provided a biodegradable laminate (hereinafter referred to as "the present biodegradable laminate") comprising a resin layer formed by applying the present biodegradable polyester solution to at least one surface of a biodegradable substrate. By applying the biodegradable polyester solution to the biodegradable substrate, the properties (e.g., adhesiveness) of the resin contained in the biodegradable polyester solution can be easily imparted to the biodegradable substrate. The biodegradable substrate is not particularly limited as long as it is biodegradable and has shape retention, but examples include paper (mainly composed of cellulose), cellophane, cellulose ester, polyvinyl alcohol, polyamino acid, polyglycolic acid, pullulan, biodegradable polyester, or these substrates onto which inorganic materials such as aluminum or silica have been vapor-deposited. Among these, paper or biodegradable polyester is preferred because of its excellent heat resistance and biodegradability. The type of paper is not particularly limited, and examples include cup base paper, kraft paper, fine paper, coated paper, tissue paper, glassine paper, and paperboard.

[0041] Examples of biodegradable polyesters include aliphatic polyester resins such as polybutylene succinate (PBS)-based resins, polycaprolactone (PCL)-based resins, and polyhydroxyalkanoate-based resins, and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate (PBAT)-based resins, polybutylene sebacate terephthalate-based resins, and polybutylene succinate terephthalate-based resins.

[0042] The type of biodegradable substrate can be appropriately selected depending on the application of the present laminate. If necessary, a water-resistant agent, a water-repellent agent, an inorganic substance, or the like may be added to the biodegradable substrate, and the biodegradable substrate may be subjected to a surface treatment such as an oxygen barrier layer coating or a water vapor barrier coating. The present biodegradable laminate can be produced, for example, by applying the present biodegradable polyester solution to one or both surfaces of a substrate layer, and then drying the solution as necessary. As a method for producing the biodegradable laminate, any known method can be appropriately used, and there is no particular limitation.

[0043] In one embodiment of the present invention, a method for producing a laminate (also referred to as "a method for producing the present laminate") includes a step of applying the present biodegradable polyester solution to one or both sides of a substrate layer, and can further include a step of drying the applied biodegradable polyester solution. In one embodiment of the present invention, the method for producing the laminate may include the following steps: (a) a step of producing the solution, (b) a step of unwinding a substrate layer, (c) a step of applying the solution to the substrate layer, and (d) a drying step. Alternatively, instead of the application step (C), the method may include a dipping step of dipping the substrate in the solution to adhere the solution to the substrate surface.

[0044] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Example]

[0045] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0046] [Raw material resin] X131A: Kaneka Biodegradable Polymer Green Planet® X131A (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), hydroxyhexanoate unit content (HH ratio) = 6 mol, Mw = 580,000), manufactured by Kaneka 151C: Kaneka Biodegradable Polymer Green Planet® 151C (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), hydroxyhexanoate unit content (HH ratio) = 11 mol, Mw = 610,000), manufactured by Kaneka.

[0047] [Measurement and evaluation methods] The evaluations in the examples and comparative examples were carried out by the following methods.

[0048] (solid content concentration) The solid content concentration in a substantially saturated state was measured as follows. PHBH resin (resin weight A0 (g)) was added to various organic solvents (solvent weight S0 (g)) and then heated to 60°C. After heating, the solution was immediately filtered through a PTFE filter (pore size: 0.22 μm) to obtain a PHBH solution (solution weight S1 (g)) as a biodegradable polyester solution. The solvent was removed from the obtained PHBH solution in a hot air oven to obtain the dissolved PHBH resin solid content (dissolved resin weight A1 (g)). The solid content concentration was calculated using the following formula. Solid concentration (%) = Dissolved resin weight A1 (g) / Solution weight S1 (g)) × 100

[0049] (Adhesiveness) The biodegradable polyester solution was applied to unbleached kraft paper (basis weight: 150 g / m 2 The resin layer was formed by applying the resin to the 100% polyester film using a 4-mil applicator. The coated layer was then sandwiched between the same kraft paper sheets and laminated using a 2 kg roller. The resulting laminate was then heated and dried in an oven at 60°C for 1 hour to prepare a sample (laminate). The obtained sample was cut into a width of 15 mm, and the kraft paper on both sides of the resin layer was grasped by hand and peeled off to evaluate the adhesiveness. <Evaluation> ○: Cohesive failure of the paper was observed on the entire peeled surface. △: Cohesive failure of the paper was observed on part of the peeled surface. ×: No cohesive failure of the paper was observed on the peeled surface.

[0050] (Ink evaluation) After drying, the biodegradable ink droplets on the sample were pressed with a finger to evaluate the ink properties. <Evaluation> ○: Good (ink does not transfer to the finger and stays on the paper) △: Fairly good (some ink was transferred to the finger in some areas.) ×: Unsuitable (ink transfers to finger).

[0051] Example 1 (Preparation of adhesive) Acetone was used as a solvent, and X131A was added as a resin raw material to prepare a biodegradable polyester solution according to the above-mentioned method for measuring solid content, and the solid content was measured. However, after filtering the obtained biodegradable polyester solution through a PTFE filter, the obtained solution was slightly cloudy due to partial evaporation of acetone. The prepared solution was used as an adhesive solution and applied to unbleached kraft paper (basis weight: 150 g / m 2 ) using a 4-mil applicator. The coated layer was then sandwiched between the same kraft paper and laminated using a 2 kg roller. The samples were then heated and dried in an oven at 60°C for 1 hour, and their adhesion was evaluated. The adhesion was generally good, but there were some areas where the adhesion to the kraft paper was insufficient due to resin that precipitated during the preparation of the solution, and in some cases cohesive failure of the paper was not observed. The solids concentration of the biodegradable polyester solution and the results of the adhesiveness evaluation are shown in Table 1.

[0052] (Ink Preparation) A biodegradable polyester solution was prepared using acetone as the solvent and X131A as the resin raw material, following the solids concentration measurement method described above. Two parts of titanium dioxide powder were then added as a pigment. The solution was then heated in an oven at 60°C for six hours, and the pigment was dispersed using a homogenizer to produce a biodegradable ink. 2 ml of ink solution was dropped onto black paper using a dropper and dried at 60°C for 1 hour to prepare a sample, which was then used to evaluate the ink properties. The ink properties were generally good, but there were some areas where the ink was transferred to the finger due to resin that precipitated during the preparation of the solution. The evaluation results of the ink properties are shown in Table 1.

[0053] Example 2 (Preparation of adhesive) Using 1,3-dioxolane as a solvent and adding X131A as a resin raw material, a biodegradable polyester solution was prepared according to the above-mentioned method for measuring solid content, and the solid content was measured. The prepared solution was used as an adhesive solution and applied to unbleached kraft paper (basis weight: 150 g / m 2 The biodegradable polyester solution was applied to a 1000-millimeter sheet of paper (approx. 1000 mm thick) using a 4-mil applicator. The coated layer was then sandwiched between the same kraft paper sheets and laminated using a 2 kg roller. The sheets were then heated and dried in an oven at 60°C for 1 hour to prepare samples for evaluation of adhesiveness. The solids concentration of the biodegradable polyester solution and the results of the adhesiveness evaluation are shown in Table 1.

[0054] (Ink Preparation) A biodegradable polyester solution was prepared using 1,3-dioxolane as the solvent and X131A as the resin raw material, following the solids concentration measurement method described above. Two parts of titanium dioxide powder were then added as a pigment. The solution was then heated in an oven at 60°C for six hours, and the pigment was dispersed using a homogenizer to produce a biodegradable ink. 2 ml of the ink solution was dropped onto black paper using a dropper and dried at 60°C for 1 hour to prepare a sample, which was then used to evaluate the ink properties. The evaluation results of the ink properties are shown in Table 1.

[0055] Examples 3 to 14 The solids concentration, adhesiveness, and ink properties of the biodegradable polyester solution were evaluated in the same manner as in Example 1, except that the raw material resins and organic solvents shown in Table 1 were used. The evaluation results are shown in Table 1.

[0056] Comparative Example 1 Using methylene chloride as the solvent and adding 151C as the resin raw material, an attempt was made to prepare a biodegradable polyester solution according to the above-mentioned method for measuring solid concentration. However, due to the high volatility of the solvent when filtering through a PTFE filter, solids precipitated on the equipment, etc., and the values ​​varied in the range of 10% to 15 wt%, making it impossible to obtain a biodegradable polyester solution whose concentration could be accurately measured. Adhesion and ink properties could not be properly evaluated because the solvent volatilized during operation. Comparative Example 2 A biodegradable polyester solution was prepared in the same manner as in Example 1, except that xylene was used as the solvent and X131A was used as the resin raw material, and the solids concentration of the resulting biodegradable polyester solution was measured. Next, the adhesiveness and ink properties were evaluated in the same manner as in Example 1, but drying was insufficient, and both were rated x. Comparative Example 3 A biodegradable polyester solution was prepared in the same manner as in Example 1, except that xylene was used as the solvent and 151C was used as the resin raw material, and the solids concentration of the resulting biodegradable polyester solution was measured. Next, the adhesiveness and ink properties were evaluated in the same manner as in Example 1, but drying was insufficient, and both were rated x. [Table 1]

[0057] 〔result〕 As can be seen from Table 1, in the examples, biodegradable polyester solutions were obtained using non-halogenated organic solvents. Furthermore, it was shown that the biodegradable adhesives containing the biodegradable polyester solutions produced in the examples had excellent adhesive properties. Furthermore, it was shown that the biodegradable inks containing the biodegradable polyester solutions produced in the examples had good ink properties. On the other hand, in the comparative examples, it is clear that a solution of biodegradable polyester resin could not be prepared, or that the adhesiveness and ink properties were insufficient.

[0058] From the above, it was found that the biodegradable polyester solution of the present invention containing a non-halogen-based organic solvent has a low environmental impact and is excellent in secondary processability. [Industrial Applicability]

[0059] The biodegradable polyester solution of the present invention can be suitably used in various fields including paints, adhesives, inks, fiber processing, sheet / film processing, paper processing, etc.

Claims

1. A biodegradable polyester solution containing poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer and a non-halogen-based organic solvent, the average content of 3-hydroxyhexanoate in the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer is less than 16 mol %, the non-halogenated organic solvent is an organic solvent having 3 to 6 carbon atoms and a boiling point of 60°C or higher, and is at least one selected from the group consisting of aliphatic ether solvents and aliphatic ketone solvents; The biodegradable polyester solution has a solids concentration of the copolymer in the biodegradable polyester solution of 0.01 to 10% by weight.

2. 2. The biodegradable polyester solution according to claim 1, which is substantially free of insoluble matter derived from the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer.

3. The biodegradable polyester solution according to claim 1 or 2, wherein the organic solvent is at least one selected from the group consisting of tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone.

4. The biodegradable polyester solution according to any one of claims 1 to 3, wherein the average content of 3-hydroxyhexanoate in the copolymer is 10 mol% or more and less than 16%.

5. A biodegradable adhesive comprising the biodegradable polyester solution according to any one of claims 1 to 4.

6. A biodegradable ink comprising the biodegradable polyester solution according to any one of claims 1 to 4 and a pigment and / or a dye.

7. A coating material comprising a substrate and a resin layer on at least a portion of a surface of the substrate, A coating material, wherein the resin layer is formed by applying the biodegradable polyester solution according to any one of claims 1 to 4 to the substrate.

8. A biodegradable laminate comprising a biodegradable substrate and a resin layer on at least one surface of the biodegradable substrate, A biodegradable laminate, wherein the resin layer is formed by applying the biodegradable polyester solution according to any one of claims 1 to 4 to the biodegradable substrate.

9. The biodegradable laminate according to claim 8, wherein the biodegradable substrate is paper or a biodegradable polyester.

10. A method for producing a biodegradable laminate comprising a biodegradable substrate and a resin layer, A method for producing a biodegradable laminate, comprising a coating step of coating the biodegradable polyester solution according to any one of claims 1 to 4 onto at least one surface of the biodegradable substrate to form the resin layer.

11. The method for producing a biodegradable laminate according to claim 10, wherein the biodegradable substrate is paper or a biodegradable polyester.

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