Resin Composition and Resin Film

Abstract

To provide a resin composition and a resin film which have good mechanical properties and gas barrier properties while having biodegradability.SOLUTION: The resin composition contains a poly(3-hydroxyalkanoate)-based resin component (A) and a second resin component (B). The component (A) contains: a copolymer (A1) of a 3-hydroxybutyrate unit and a 3-hydroxyhexanoate unit, the content ratio of the 3-hydroxyhexanoate unit being 1-6 mol%; and a copolymer (A2) of a 3-hydroxybutyrate unit and a 3-hydroxyhexanoate unit, the content ratio of the 3-hydroxyhexanoate unit being 24 mol% or more. The proportion of the copolymer (A2) in the component (A) is 40 wt.% or more. The component (B) is selected from the group consisting of an aliphatic-aromatic polyester-based resin, polybutylene succinate, polybutylene succinate adipate, and polylactic acid.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition and a resin film formed from the resin composition.

Background Art

[0002] Petroleum-derived plastics are discarded in large quantities every year, and environmental pollution caused by these large amounts of waste has been taken up as a serious problem. Therefore, alternatives to biodegradable plastics are being considered.

[0003] In agricultural applications, resin films are utilized as mulch films that cover the surface of fields for the purpose of regulating soil temperature, suppressing soil drying and weed growth, etc. The resin film can efficiently fix fumigants in the soil, eliminate pests such as nematodes, bacteria, and fungi, and contribute to the production of high-quality vegetables, fruits, and flowers while suppressing undesirable side effects without releasing them into the environment. As the resin material contained in such a resin film, polybutylene adipate terephthalate (PBAT) is widely used among biodegradable plastics. Since PBAT has soil degradability, it can be incorporated into the soil after harvesting of agricultural crops, which can reduce labor.

[0004] Patent Document 1 describes that a polyester film containing 80 to 95% by mass of a biodegradable polyester such as PBAT, 5 to 20% by mass of polyhydroxyalkanoate, 10 to 20% by mass of calcium carbonate, and 3 to 15% by mass of talc can be used as an agricultural mulch film.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Polybutylene adipate terephthalate (PBAT) has the characteristic of low gas barrier properties. Therefore, when used as an agricultural multifilm, fumigants may escape into the environment, which may prevent the achievement of the intended purpose and may also have an undesirable impact on the environment. Therefore, in order to improve the gas barrier properties of the film, it has been proposed to blend poly(3-hydroxyalkanoate), which is also a biodegradable resin, with PBAT. However, when poly(3-hydroxyalkanoate) is blended, although the gas barrier properties of the film can be improved, the mechanical properties, especially the tear resistance, tend to deteriorate rapidly. Insufficient tear resistance causes problems when used as an agricultural multifilm. Patent Document 1 describes improving tear resistance by blending calcium carbonate and talc, but it is necessary to blend two specific types of inorganic fillers in specific amounts, and the composition of the film is extremely limited.

[0007] In view of the above situation, an object of the present invention is to provide a resin composition and a resin film that have biodegradability and good mechanical properties and gas barrier properties.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that in addition to blending poly(3-hydroxyalkanoate) with a second resin component such as polybutylene adipate terephthalate, by designing poly(3-hydroxyalkanoate) to be composed of two copolymers having different constituent monomer content ratios, it is possible to achieve both biodegradability and good mechanical properties and gas barrier properties, and thus the present invention has been completed.

[0009] That is, the present invention is a resin composition containing a poly(3-hydroxyalkanoate) resin component (A) and a second resin component (B), wherein the poly(3-hydroxyalkanoate) resin component (A) is a copolymer (A1) of 3-hydroxybutyrate units and 3-hydroxyhexanoate units with the content ratio of 3-hydroxyhexanoate units being 1 to 6 mol%, and a copolymer (A2) of 3-hydroxybutyrate units and 3-hydroxyhexanoate units with the content ratio of 3-hydroxyhexanoate units being 24 mol% or more, and the proportion of the copolymer (A2) in the whole poly(3-hydroxyalkanoate) resin component (A) is 40% by weight or more, and the second resin component (B) is at least one selected from the group consisting of aliphatic-aromatic polyester resins, polybutylene succinate, polybutylene succinate adipate, and polylactic acid. Preferably, the aliphatic-aromatic polyester resin has repeating units derived from an aliphatic dicarboxylic acid, repeating units derived from an aromatic dicarboxylic acid, and repeating units derived from a diol, the aliphatic dicarboxylic acid is at least one selected from the group consisting of succinic acid, adipic acid, azelaic acid, sebacic acid, brassilic acid, pimelic acid, suberic acid, fumaric acid, and itaconic acid, the aromatic dicarboxylic acid is at least one selected from the group consisting of terephthalic acid, isophthalic acid, and furandicarboxylic acid, and the diol is at least one selected from the group consisting of 1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol. Preferably, the proportion of the poly(3-hydroxyalkanoate) resin component (A) in the total of the poly(3-hydroxyalkanoate) resin component (A) and the second resin component (B) is 10% by weight or more and 50% by weight or less. Preferably, the second resin component (B) contains polybutylene adipate terephthalate as the aliphatic-aromatic polyester resin. Preferably, the proportion of polybutylene adipate terephthalate in the whole second resin component (B) is 50% by weight or more. Preferably, the second resin component (B) is polybutylene adipate terephthalate and at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polylactic acid. Preferably, the poly(3-hydroxyalkanoate) resin component (A) has a crosslinked structure. The resin composition may further contain a plasticizer. The present invention also relates to a resin film formed from the resin composition. Preferably, the thickness is 10 μm or more and 100 μm or less. The resin film may be an inflation molded article. Preferably, the resin film is an agricultural multifilm.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a resin composition and a resin film that have biodegradability and good mechanical properties and gas barrier properties. The resin composition and the resin film can achieve good mechanical properties without containing a specific amount of calcium carbonate and / or a specific amount of talc disclosed in Patent Document 1. Since the resin film has biodegradability and has good tear resistance and gas barrier properties, it can be suitably used as an agricultural multifilm.

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0012] The present embodiment relates to a resin composition containing a poly(3-hydroxyalkanoate) resin component (A) and a second resin component (B).

[0013] (Poly(3-hydroxyalkanoate) resin component (A)) The poly(3-hydroxyalkanoate) resin component (A) is a mixture of at least two types of copolymers of 3-hydroxybutyrate units and 3-hydroxyhexanoate units. Specifically, it includes a copolymer (A1) of 3-hydroxybutyrate units and 3-hydroxyhexanoate units with a 3-hydroxyhexanoate unit content ratio of 1 to 6 mol%, and a copolymer (A2) of 3-hydroxybutyrate units and 3-hydroxyhexanoate units with a 3-hydroxyhexanoate unit content ratio of 24 mol% or more.

[0014] The copolymer (A1) is a resin with higher crystallinity than the copolymer (A2). The content ratio of 3-hydroxybutyrate units contained in the copolymer (A1) is preferably higher than the average content ratio of 3-hydroxybutyrate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin component (A). The content ratio of 3-hydroxyhexanoate units contained in the copolymer (A1) is 1 to 6 mol%, preferably 1 to 5 mol%, and more preferably 2 to 4 mol%.

[0015] From the perspective of achieving both mechanical properties and productivity, the weight-average molecular weight of the copolymer (A1) is preferably 200,000 to 1,000,000, more preferably 220,000 to 800,000, and even more preferably 250,000 to 600,000. Only one type of the copolymer (A1) may be used, or two or more types may be used in combination.

[0016] The copolymer (A2) is a resin with lower crystallinity than the copolymer (A1). The content ratio of 3-hydroxybutyrate units contained in the copolymer (A2) is preferably lower than the average content ratio of 3-hydroxybutyrate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin component (A). The content ratio of 3-hydroxyhexanoate units contained in the copolymer (A2) is 24 to 99 mol%, preferably 24 to 50 mol%, more preferably 25 to 35 mol%, and particularly preferably 26 to 30 mol%.

[0017] From the viewpoint of achieving both good mechanical properties and productivity, the weight-average molecular weight of the copolymer (A2) is preferably from 200,000 to 2,500,000, more preferably from 250,000 to 2,300,000, and even more preferably from 300,000 to 2,000,000. Only one type of the copolymer (A2) may be used, or two or more types may be used in combination.

[0018] From the viewpoint of achieving both good mechanical properties and gas barrier properties, the proportion of the copolymer (A2) in the total poly(3-hydroxyalkanoate) resin component (A) is set to 40% by weight or more. When the proportion of the copolymer (A2) is less than 40% by weight, the mechanical properties cannot be sufficiently improved. The proportion is preferably 45% by weight or more, more preferably 50% by weight or more, and even more preferably 52% by weight or more. Also, from the viewpoints of productivity and gas barrier properties, the upper limit of the proportion of the copolymer (A2) is preferably 75% by weight or less, more preferably 70% by weight or less, and even more preferably 65% by weight or less.

[0019] From the viewpoint of achieving both good mechanical properties and gas barrier properties, the proportion of the copolymer (A1) in the total poly(3-hydroxyalkanoate) resin component (A) is preferably 60% by weight or less, more preferably 55% by weight or less, even more preferably 50% by weight or less, and still more preferably 48% by weight or less. Also, from the viewpoints of productivity and gas barrier properties, the lower limit of the proportion of the copolymer (A1) is preferably 25% by weight or more, more preferably 30% by weight or more, and even more preferably 35% by weight or more.

[0020] The average content ratios of 3-hydroxybutyrate units and 3-hydroxyhexanoate units in all monomer units constituting the poly(3-hydroxyalkanoate)-based resin component (A) containing the copolymer (A1) and the copolymer (A2) are, from the viewpoint of achieving both mechanical properties and productivity, preferably 3-hydroxybutyrate unit / 3-hydroxyhexanoate unit = 93 / 7 to 80 / 20 (mol% / mol%), more preferably 92 / 8 to 81 / 19 (mol% / mol%), still more preferably 90 / 10 to 82 / 18 (mol% / mol%), even more preferably 88 / 12 to 82 / 18 (mol% / mol%), and particularly preferably 86 / 14 to 82 / 18 (mol% / mol%).

[0021] The average content ratio of each monomer unit in all monomer units constituting the copolymer (A1), the copolymer (A2), or the poly(3-hydroxyalkanoate)-based resin component (A) 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 ratio means the average molar ratio. The average content ratio of each monomer unit in all monomer units constituting the poly(3-hydroxyalkanoate)-based resin component (A) means the molar ratio of each monomer unit in all monomer units contained in the whole poly(3-hydroxyalkanoate)-based resin component (A) containing the copolymer (A1) and the copolymer (A2).

[0022] The weight average molecular weight of the whole poly(3-hydroxyalkanoate)-based resin component (A) is not particularly limited, but from the viewpoint of achieving both mechanical properties and productivity, it is preferably 200,000 to 2,000,000, more preferably 250,000 to 1,500,000, and still more preferably 300,000 to 1,000,000.

[0023] The weight average molecular weight of the copolymer (A1), copolymer (A2), or poly(3-hydroxyalkanoate) resin component (A) can be measured in terms of polystyrene using gel permeation chromatography (HPLC GPC system manufactured by Shimadzu Corporation) with a chloroform solution. As the column for the gel permeation chromatography, a column suitable for measuring the weight average molecular weight may be used.

[0024] The method for producing the copolymer (A1) or copolymer (A2) is not particularly limited and may be a production method by chemical synthesis or a production method by microorganisms. Among them, the production method by microorganisms is preferred. For the production method by microorganisms, known methods can be applied. For example, as bacteria that produce a copolymer (P3HB3HH) of 3-hydroxybutyrate units and 3-hydroxyhexanoate units, Aeromonas caviae and the like are known. In particular, in order to increase the productivity of P3HB3HH, the Alcaligenes eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, p4821-4830 (1997)) into which the genes of the P3HA synthase group have been introduced is more preferred, and microbial cells in which P3HB3HH is accumulated in the cells by culturing these microorganisms under appropriate conditions are used. In addition to the above, according to the poly(3-hydroxyalkanoate) resin to be produced, genetically modified microorganisms into which various poly(3-hydroxyalkanoate) resin synthesis-related genes have been introduced may be used, or the culture conditions including the type of substrate may be optimized.

[0025] The method for obtaining the blend of the copolymer (A1) and the copolymer (A2) is not particularly limited, and it may be a method of directly obtaining the blend by microbial production or a method of directly obtaining the blend by chemical synthesis. Further, the copolymer (A1) and the copolymer (A2) produced individually may be melt-kneaded using an extruder, a kneader, a Banbury mixer, a roll, etc. to obtain a blend, or the copolymer (A1) and the copolymer (A2) may be dissolved in a solvent respectively, mixed and dried to obtain a blend.

[0026] (Crosslinked structure) The poly(3-hydroxyalkanoate)-based resin component (A) may not have a crosslinked structure or may have a crosslinked structure introduced by reaction with an organic peroxide. By introducing a crosslinked structure into the resin component (A), the productivity of the film (particularly the productivity in inflation molding) can be improved, and the mechanical properties can also be enhanced.

[0027] When the poly(3-hydroxyalkanoate)-based resin component (A) has a crosslinked structure, the resin component (A) may have a crosslinked structure introduced throughout the whole or may contain both a component with a crosslinked structure introduced and a component without a crosslinked structure introduced. In particular, from the viewpoints of productivity and mechanical properties, it is preferable that the copolymer (A2) contains a component with a crosslinked structure introduced.

[0028] The organic peroxide used for introducing a crosslinked structure into the poly(3-hydroxyalkanoate) resin component (A) is not particularly limited. For example, diisobutyl peroxide, cumyl peroxyneodecanoate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl) peroxydicarbonate, bis(2-ethylhexyl) peroxydicarbonate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, disuccinic peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butyl peroxy 2-ethylhexyl carbonate, t-butyl peroxyisopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-amyl peroxy 3,5,5-trimethylhexanoate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-di-t-butylperoxybutane, etc. can be mentioned. Among them, dibenzoyl peroxide, t-butyl peroxy 2-ethylhexyl carbonate, and t-butyl peroxyisopropyl carbonate are preferable. As the organic peroxide, one kind may be used alone, or two or more kinds may be used in combination.

[0029] Organic peroxides are used in various forms such as solid or liquid, and may be in a liquid form diluted with a diluent or the like. Among them, an organic peroxide in a form that can be mixed with the poly(3-hydroxyalkanoate) resin component (A) (particularly, an organic peroxide that is liquid at room temperature (25 °C)) is preferable because it can be uniformly dispersed in the poly(3-hydroxyalkanoate) resin component (A) and it is easy to suppress local modification reactions.

[0030] From the viewpoint of improving productivity and mechanical properties, the amount of the organic peroxide used is preferably 0.01 to 0.5 parts by weight, more preferably 0.05 to 0.4 parts by weight, and even more preferably 0.1 to 0.3 parts by weight with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin component (A).

[0031] In addition, the poly(3-hydroxyalkanoate) resin component (A) having a crosslinked structure introduced by reaction with an organic peroxide, and the resin composition or resin film containing the same may contain components derived from the organic peroxide (for example, decomposition products of the organic peroxide, compounds derived from the decomposition products, etc.).

[0032] The poly(3-hydroxyalkanoate) resin component (A) having a crosslinked structure can preferably be obtained by charging the poly(3-hydroxyalkanoate) resin component and the organic peroxide into an extruder and melt-kneading them. Thereby, the poly(3-hydroxyalkanoate) resin component can be uniformly crosslinked. Further, in addition to the poly(3-hydroxyalkanoate) resin component and the organic peroxide, other components such as a nucleating agent, a lubricant, an organic or inorganic filler as described later may also be charged into the extruder and melt-kneaded.

[0033] In the above melt-kneading, the poly(3-hydroxyalkanoate) resin component (A) or the copolymer (A1) and the copolymer (A2) and the organic peroxide may be individually charged into the extruder, or each component may be mixed and then charged into the extruder.

[0034] The above melt-kneading can be carried out according to known or conventional methods. For example, it can be carried out using an extruder (single-screw extruder, twin-screw extruder), a kneader, etc. The conditions for melt-kneading are not particularly limited and can be set as appropriate. However, it is preferable to set the resin temperature and residence time at which the organic peroxide can complete the reaction during melt-kneading. Specifically, it is preferable to carry out melt-kneading in the range where the resin temperature measured by the thermometer of the die is 155°C or higher and 175°C or lower. Also, it is preferable to carry out melt-kneading so that the residence time in the extruder is 60 seconds or longer and 300 seconds or shorter.

[0035] When the poly(3-hydroxyalkanoate) - based resin component (A) contains both a component into which a crosslinked structure is introduced and a component into which a crosslinked structure is not introduced, first, a part of the resin component (A) is melt-kneaded with the above-mentioned organic peroxide to introduce a crosslinked structure, and then the remaining resin component (A) may be mixed.

[0036] (Second resin component (B)) The resin composition according to the present embodiment contains, as the second resin component (B), at least one selected from the group consisting of an aliphatic - aromatic polyester - based resin, polybutylene succinate, polybutylene succinate adipate, and polylactic acid. Among these, since the mechanical properties are good, it is preferable that the second resin component (B) contains at least an aliphatic - aromatic polyester - based resin. The aliphatic - aromatic polyester - based resin is a polyester polymer having a repeating unit derived from an aliphatic dicarboxylic acid, a repeating unit derived from an aromatic dicarboxylic acid, and a repeating unit derived from a diol.

[0037] Examples of the aliphatic dicarboxylic acid that is a constituent component of the aliphatic - aromatic polyester - based resin include succinic acid, adipic acid, azelaic acid, sebacic acid, brassilic acid, pimelic acid, suberic acid, fumaric acid, and itaconic acid. These may be used alone or in combination of two or more. Among them, adipic acid, azelaic acid, sebacic acid, and succinic acid are preferable.

[0038] Examples of the aromatic dicarboxylic acids that are components of the aliphatic-aromatic polyester resin include terephthalic acid, isophthalic acid, and furandicarboxylic acid. These may be used alone or in combination of two or more. Among them, terephthalic acid and furandicarboxylic acid are preferred.

[0039] Examples of the diols that are components of the aliphatic-aromatic polyester resin include 1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol. These may be used alone or in combination of two or more. Among them, 1,4-butanediol is preferred.

[0040] Specific examples of the aliphatic-aromatic polyester resin include, for example, polybutylene succinate terephthalate (PBST), polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT), polybutylene azelate terephthalate (PBAzT), and the like. Among them, from the viewpoints of industrial availability, heat resistance, and / or biodegradability, polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT), and polybutylene azelate terephthalate (PBAzT) are preferred, and polybutylene adipate terephthalate (PBAT) is particularly preferred.

[0041] From the viewpoint of mechanical properties, the composition ratio of the repeating units of the aliphatic-aromatic polyester resin is preferably such that the composition ratio of the aliphatic dicarboxylic acid unit / aromatic dicarboxylic acid unit is 95 / 5 to 30 / 70 (mol / mol), and more preferably 90 / 10 to 40 / 60 (mol / mol). When the total of the aliphatic dicarboxylic acid unit and the aromatic dicarboxylic acid unit is 100 mol%, the mechanical properties are good if the aromatic dicarboxylic acid unit is 5 mol% or more. Also, the biodegradability is excellent if the aromatic dicarboxylic acid unit is 70 mol% or less.

[0042] The weight average molecular weight of the aliphatic-aromatic polyester resin is not particularly limited, but is preferably from 10,000 to 500,000, more preferably from 20,000 to 400,000. If the weight average molecular weight is 500,000 or less, processing becomes easy, and if it is 10,000 or more, the physical properties are excellent. The weight average molecular weight of the aliphatic-aromatic polyester resin can be determined by the same method as the weight average molecular weight of the poly(3-hydroxyalkanoate) resin component (A).

[0043] Particularly preferred PBAT as the aliphatic-aromatic polyester resin refers to a random copolymer of 1,4-butanediol, adipic acid, and terephthalic acid. PBAT obtained by the reaction of (a) a mixture mainly composed of 35 to 95 mol% of adipic acid or its ester-forming derivative or a mixture thereof, 5 to 65 mol% of terephthalic acid or its ester-forming derivative or a mixture thereof (the total of mol% is 100 mol%) and (b) a mixture containing butanediol (however, the molar ratio of (a) to (b) is 0.4:1 to 1.5:1), as described in Japanese Patent Application Laid-Open No. 10-508640, etc., is preferred. Commercially available products of PBAT include "Ecovio F blend C1200" (registered trademark) manufactured by BASF.

[0044] When the second resin component (B) contains PBAT, the proportion of PBAT in the whole of the second resin component (B) is not particularly limited, but is preferably 50% by weight or more and 100% by weight or less so as to obtain the advantages of PBAT blending. More preferably, it is 60% by weight or more, still more preferably 70% by weight or more, and even more preferably 80% by weight or more. Also, the upper limit is more preferably 95% by weight or less.

[0045] When the proportion of PBAT in the total amount of the second resin component (B) is less than 100% by weight, the second resin component (B) preferably contains PBAT and at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polylactic acid, and particularly preferably contains PBAT and polylactic acid. By using PBAT in combination with a resin other than PBAT, the productivity of the film (particularly the productivity in inflation molding) can be improved.

[0046] In the resin composition, the proportion of the poly(3-hydroxyalkanoate) - based resin component (A) is not particularly limited and can be appropriately determined in consideration of mechanical strength, gas barrier properties, biodegradability, etc. However, from the balance of each physical property, the proportion of the resin component (A) relative to the total of the resin component (A) and the second resin component (B) is preferably 10% by weight or more and 50% by weight or less. By setting the proportion of the resin component (A) to 10% by weight or more, the gas barrier property and biodegradability can be made good. More preferably 15% by weight or more, still more preferably 20% by weight or more, and even more preferably 25% by weight or more. Also, by setting the proportion of the resin component (A) to 50% by weight or less, the mechanical properties can be made good. More preferably 45% by weight or less, still more preferably 40% by weight or less, and even more preferably 35% by weight or less.

[0047] From the same viewpoint, the proportion of the second resin component (B) relative to the total of the resin component (A) and the second resin component (B) is preferably 50% by weight or more and 90% by weight or less. By setting the proportion of the second resin component (B) to 90% by weight or less, the gas barrier property and biodegradability can be made good. More preferably 85% by weight or less, still more preferably 80% by weight or less, and even more preferably 75% by weight or less. Also, by setting the proportion of the resin component (B) to 50% by weight or more, the mechanical properties can be made good. More preferably 55% by weight or more, still more preferably 60% by weight or more, and even more preferably 65% by weight or more.

[0048] (Additive) The resin film according to this embodiment may contain other components. For example, it may contain an organic or inorganic filler or the like within a range that does not inhibit the effects of the invention. The content of the organic or inorganic filler can be set as appropriate and is not particularly limited. The organic or inorganic filler can be used alone or in combination of two or more kinds.

[0049] (Silica) The resin film according to this embodiment may contain silica as an inorganic filler.

[0050] The type of the silica is not particularly limited, but from the viewpoint of versatility, synthetic amorphous silica produced by a dry method or a wet method is preferable. Also, either a hydrophobically treated or non-hydrophobically treated one can be used, and it can be used alone or in combination of two or more kinds.

[0051] As the silica, silica having an adsorbed moisture content of 0.5% by weight or more and 7% by weight or less is preferable. The adsorbed moisture content can be measured, for example, using an electromagnetic balance MX-50 manufactured by Ken Seiko Kogyo Co., Ltd., and taking the volatile content at 160°C as the adsorbed moisture content. When the adsorbed moisture content is greater than 7% by weight, it becomes difficult to disperse due to the cohesive force of the moisture adsorbed on the silica surface or between particles, and fish eyes may occur during molding, resulting in poor appearance. Conversely, when it is less than 0.5% by weight, the small amount of moisture remaining between the particles forms a crosslinked liquid film and generates a large binding force due to surface tension, and separation and dispersion tend to be extremely difficult.

[0052] The average primary particle diameter of the silica is not particularly limited as long as it can improve the tear strength of the resin film, hardly causes appearance defects such as fish eyes, and does not significantly impair transparency. However, in terms of easily obtaining the effect of improving mechanical properties such as tear strength and having excellent transparency, it is preferably 0.001 to 0.1 μm, and particularly preferably 0.005 to 0.05 μm. The average primary particle diameter is determined by arithmetically averaging the diameters of any 50 or more primary particles observed using a transmission electron microscope (TEM).

[0053] Considering the effects obtained by the blending of silica and the dispersibility of silica, etc., the blending amount (total blending amount) of the silica is preferably 1 to 12 parts by weight with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) - based resin component (A). The blending amount of the silica is more preferably 2 parts by weight or more, and even more preferably 4 parts by weight or more. Also, it is more preferably 11 parts by weight or less, and even more preferably 10 parts by weight or less.

[0054] For the purpose of improving the dispersibility of the silica, it is preferable to use the silica in combination with a dispersion aid.

[0055] Examples of the dispersion aid include glycerin ester compounds, adipic acid ester compounds, polyether ester compounds, phthalic acid ester compounds, isosorbide ester compounds, polycaprolactone compounds, and the like. Among these, modified glycerin compounds such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate; adipic acid ester compounds such as diethylhexyl adipate, dioctyl adipate, and diisononyl adipate; and polyether ester compounds such as polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate are preferred because of their excellent affinity for the resin component and difficulty in bleeding. Furthermore, those containing a large amount of biomass-derived components are particularly preferred because they can increase the biomass degree of the entire composition. Examples of such dispersion aids include acetylated monoglycerides BIOCIZER and PL series from Riken Vitamin Co., Ltd., and Polysorb series from ROQUETTE. The dispersion aid can be used alone or in combination of two or more kinds.

[0056] The blending amount (total blending amount) of the dispersion aid is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin component (A), considering the effects obtained by blending the dispersion aid and the possibility of bleeding out of the dispersion aid. The blending amount of the dispersion aid is more preferably 0.3 parts by weight or more, and even more preferably 0.5 parts by weight or more. Also, it is more preferably 10 parts by weight or less, and even more preferably 5 parts by weight or less.

[0057] In addition to organic or inorganic fillers, within the range that does not inhibit the effects of the invention, colorants such as pigments and dyes used as ordinary additives, odor absorbers such as activated carbon and zeolite, fragrances such as vanillin and dextrin, antioxidants, oxidation inhibitors, weather resistance improvers, ultraviolet absorbers, lubricants, mold release agents, water repellents, antibacterial agents, fluidity improvers, and one or more of other secondary additives may be included. The content of the additive can also be set as appropriate. Hereinafter, the crystallization nucleating agent, lubricant, and plasticizer will be described in more detail.

[0058] (Crystallization Nucleating Agent) The resin film according to this embodiment may also contain a crystallization nucleating agent. Examples of the crystallization nucleating agent include polyhydric alcohols such as pentaerythritol, galactitol, and mannitol; orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, boron nitride, and the like. Among them, pentaerythritol is preferable in that it has a particularly excellent effect of promoting the crystallization of the poly(3-hydroxyalkanoate) - based resin component. The amount of the crystallization nucleating agent used is not particularly limited, but is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, and even more preferably 0.7 to 1.5 parts by weight with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) - based resin component (A). Also, one type of crystallization nucleating agent may be used, or two or more types may be used, and the usage ratio can be appropriately adjusted according to the purpose.

[0059] (Lubricant) The resin film according to this embodiment may also contain a lubricant. Examples of the lubricant include behenic acid amide, oleic acid amide, erucic acid amide, stearic acid amide, palmitic acid amide, N-stearyl behenic acid amide, N-stearyl erucic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, ethylene bis lauric acid amide, ethylene bis capric acid amide, p-phenylene bis stearic acid amide, polycondensates of ethylenediamine, stearic acid, and sebacic acid, and the like. Among them, behenic acid amide or erucic acid amide is preferable in that the lubricating effect on the poly(3-hydroxyalkanoate)-based resin component is particularly excellent. The amount of the lubricant used is not particularly limited, but is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and still more preferably 0.1 to 1.5 parts by weight with respect to 100 parts by weight of the poly(3-hydroxyalkanoate)-based resin component (A). Also, one type of lubricant may be used, or two or more types may be used, and the use ratio can be appropriately adjusted according to the purpose. However, the resin film according to this embodiment may not contain a lubricant.

[0060] (Plasticizer) The resin film according to this embodiment may contain a plasticizer. Examples of the plasticizer include glycerin ester compounds, citric acid ester compounds, sebacic acid ester compounds, adipic acid ester compounds, polyether ester compounds, benzoic acid ester compounds, phthalic acid ester compounds, isosorbide ester compounds, polycaprolactone compounds, dibasic acid ester compounds, and the like. Among them, glycerin ester compounds, citric acid ester compounds, sebacic acid ester compounds, and dibasic acid ester compounds are preferred in that they have particularly excellent plasticizing effects on the poly(3-hydroxyalkanoate)-based resin component. Examples of the glycerin ester compound include glycerin diacetomonolaurate. Examples of the citric acid ester compound include tributyl acetylcitrate. Examples of the sebacic acid ester compound include dibutyl sebacate. Examples of the dibasic acid ester compound include benzylmethyl diethylene glycol adipate. The amount of the plasticizer used is not particularly limited, but is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, and even more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the poly(3-hydroxyalkanoate)-based resin component (A). The plasticizer may be used alone or in combination of two or more, and the usage ratio can be appropriately adjusted according to the purpose.

[0061] (Resin film) The resin composition can be preferably formed into a resin film. The resin film may be a single-layer film or a multilayer film. The thickness of the resin film is not particularly limited, but is preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 80 μm or less, and even more preferably 20 μm or more and 60 μm or less.

[0062] (Method for producing resin film) The resin film according to this embodiment can be manufactured by various molding methods such as T-die extrusion molding, inflation molding, and calendar molding, but it is preferably manufactured by inflation molding.

[0063] The inflation molding refers to a molding method in which a molten resin composition is extruded in a tube shape from an extruder with a cylindrical die attached to its tip, and immediately thereafter, a gas is blown into the tube to inflate it into a balloon shape to form a tube-shaped single-layer or multilayer film. The method of the inflation molding is not particularly limited, but for example, it can be carried out using a general inflation molding machine used when molding a thermoplastic resin into a film. A general inflation molding machine refers to one in which a single cylindrical die is attached to a single-screw extruder in the case of molding a single-layer film. In the case of molding a multilayer film, it refers to one in which molten resin is poured from a plurality of extruders into a single cylindrical die according to the type of resin used, and each resin can be laminated in the die. The above single-screw extruder only needs to melt and knead the input raw material resin and obtain a constant discharge while maintaining a desired temperature. The screw shape of the single-screw extruder is not particularly limited, but those equipped with a mixing element are preferable from the viewpoint of kneading property. Also, the structure of the cylindrical die is appropriately designed according to the single-layer and laminated films and is not particularly limited, but among them, a spiral mandrel die is preferable because it generates few welds and is easy to obtain thickness uniformity.

[0064] The molding temperature in inflation molding is not particularly limited as long as the resin can be appropriately melted, but for example, 135 to 200 °C is preferable. The molding temperature here refers to the resin temperature from after the extruder to when it is discharged from the die. The resin temperature can generally be measured by a thermometer installed in the adapter, for example.

[0065] As the take-up speed in inflation molding is determined by the thickness and width of the resin film and the resin discharge amount, it can be adjusted within the range where balloon stability can be maintained. Generally, 1 to 50 m / min is preferred.

[0066] In inflation molding, an air ring that blows from the outside of the balloon can be used to solidify the discharged molten resin and stabilize the balloon. As a spraying structure of the air ring preferably used, there is a slit type in which a plurality of annular slits through which air blows are provided, and the stability of the balloon is promoted by the chambers between the slits.

[0067] After inflation molding, a step of taking up the tubular molded film to a take-up roll in a state of being folded by pinch rolls, a step of blowing air into the interface of the film folded by pinch rolls in order to easily peel off the molded film after winding, and a step of cutting the film according to the application during the take-up may be performed. As the cutting method, there are a method of cutting both ends in the width direction of the folded tubular molded film to form two films, a method of hot-cutting the tubular molded film in the width direction and forming a bag-shaped film by performing fusion bonding by heat sealing, etc. Further, a step of blowing air into the interface of the film folded immediately before cutting may be included so that cutting is easy. Further, a step of performing so-called gusset folding in which both ends of the folded tubular film are folded inward may be performed. Further, a step of printing on the film surface may be performed after folding by pinch rolls and before winding, and further, corona treatment may be performed on the film surface before printing in order to improve the printing adhesion. The printing method is not particularly limited, but examples include gravure printing and flexographic printing.

[0068] Since the resin film according to this embodiment has excellent biodegradability, it can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, hygiene products, food industry, clothing, non-clothing, packaging, automobiles, building materials, and other fields. For example, it can be used in garbage bags, shopping bags, packaging bags for vegetables and fruits, pillow packaging, delivery bags, agricultural mulch films, fumigation sheets for forestry, binding tapes including flat yarns, root wrapping films for plants, back sheets for diapers, packaging sheets, shopping bags, drainage bags, and other applications such as compost bags. In particular, since the resin film has both biodegradability, good tear strength, and gas barrier properties, it can be suitably used as an agricultural mulch film.

Example

[0069] Hereinafter, the present invention will be specifically described by way of examples, but the technical scope of the present invention is not limited by these examples.

[0070] The following raw materials were used in each example and comparative example. P3HB3HH-1: P3HB3HH (average content ratio 3HB / 3HH = 97.2 / 2.8 (mol% / mol%), weight average molecular weight is 660,000 g / mol) Manufactured according to the method described in Example 2 of International Publication WO2019 / 142845. P3HB3HH-2: P3HB3HH (average content ratio 3HB / 3HH = 71.8 / 28.2 (mol% / mol%), weight average molecular weight is 660,000 g / mol) Manufactured according to the method described in Example 9 of International Publication WO2019 / 142845. P3HB3HH-3: P3HB3HH (average content ratio 3HB / 3HH = 94 / 6 (mol% / mol%), weight average molecular weight is 400,000 g / mol) P3HB3HH-4: P3HB3HH (average content ratio 3HB / 3HH = 89 / 11 (mol% / mol%), weight average molecular weight is 600,000 g / mol)

[0071] (Organic peroxide) Perbutyl I manufactured by Nippon Yushi Co., Ltd. (t-butyl peroxyisopropyl carbonate, 1-minute half-life temperature: 159°C)

[0072] (Plasticizer) BIOCIZER manufactured by Riken Vitamin Co., Ltd. (Glycerin fatty acid ester)

[0073] (Lubricant) BNT-22H manufactured by Nippon Seika Co., Ltd. (Behenic acid amide)

[0074] (Nucleating agent) Neutralizer P manufactured by Mitsubishi Chemical Corporation (Pentaerythritol)

[0075] The following evaluations were carried out in each example and comparative example. (Tear strength) Evaluation was carried out in accordance with JIS K7128-2 Plastics - Test method for tear strength of films and sheets - Part 2: Elmendorf tear method. For inflation molded products, evaluation was carried out in both the MD and TD directions, and for T-die molded products, evaluation was carried out only in the MD direction.

[0076] (Oxygen permeability) Evaluation was carried out in accordance with JIS K 7126-1 Plastics - Films and sheets - Gas permeability test method - Part 1: Differential pressure method, Annex 2 (Gas chromatography method).

[0077] (Biodegradability [soil decomposition]) (Sample) Film with an average thickness of 40 μm and a weight of 60 - 69 mg (Test conditions) For the evaluation of biodegradability (soil decomposition), a compost was prepared by mixing plant source (soil: 150 g, cured at 23 - 28°C for 9 days), sea sand (200 g), and water (110 g). The obtained compost was put into a 900 mL glass container, and then the film (60 - 69 mg) was embedded in the compost. After that, a decomposition test was carried out while maintaining the temperature at 27 - 29°C. The moisture of the compost was replenished every week, and it was adjusted to maintain the initial weight of the compost = 460 g. The film was collected every two weeks, weighed, and the weight loss rate at the 10-week mark was recorded and evaluated as follows. 〇: 7% or more ×: 2% or less

[0078] (Example 1) Method for producing a resin film P3HB3HH-1, P3HB3HH-2, a lubricant, and a crystal nucleating agent were dry-blended at the compounding ratios shown in Table 1, and using a co-rotating twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.: TEM26ss), melt-kneaded at a set temperature of 120°C or higher and 170°C or lower and a screw rotation speed of 100 rpm, and strand-cut to obtain a melt-kneaded product. The obtained melt-kneaded product and Ecovio(R) M2351 (a mixture of PBAT and polylactic acid (weight ratio 9:1), manufactured by BASF) as the second resin component (B) were dry-blended at a weight ratio of total P3HB3HH: second resin component (B) = 30:70, and fed into an inflation molding machine (manufactured by Hokushin Sangyo Co., Ltd.) connected to a die equipped with a cylindrical die lip with a diameter of 100 mm and having a single-screw with L / D = 32 to produce a film. The obtained film was evaluated for tear strength, oxygen permeability, and biodegradability, and the results are shown in Table 1.

[0079] (Example 2) Inflation molding was carried out in the same manner as in Example 1 except that an organic peroxide and a plasticizer were further added at the compounding ratios shown in Table 1 to obtain a melt-kneaded product, and a film was produced. The various evaluation results are shown in Table 1.

[0080] (Example 3) P3HB3HH-1, P3HB3HH-2, a lubricant, a crystal nucleating agent, and an organic peroxide were dry-blended at the compounding ratios shown in Table 1, and after obtaining a melt-kneaded product in the same manner as in Example 1, the obtained melt-kneaded product was dry-blended with the amount of P3HB3HH-3 shown in Table 1, and further, Ecovio M2351 was dry-blended at a weight ratio of total P3HB3HH: second resin component (B) = 30:70, and fed into the inflation molding machine described in Example 1 to produce a film. The various evaluation results are shown in Table 1.

[0081] (Example 4) Inflation molding was carried out in the same manner as in Example 3 except that a plasticizer was further added in the blending ratio shown in Table 1 to obtain a melt-kneaded product, and a film was produced. The various evaluation results are shown in Table 1.

[0082] (Example 5) A film was produced in the same manner as in Example 4 except that the blending ratios of P3HB3HH-1, P3HB3HH-2, P3HB3HH-3, and the organic peroxide were changed as shown in Table 1, and T-die molding was carried out instead of inflation molding. In T-die molding, compound pellets were put into a single-screw extruder (20 mmφ, L / D = 20, Toyo Seiki Seisaku-sho, Ltd. Laboplastmill), extruded from a T-die attached to the tip, and taken up by a metal roll to obtain a film with a predetermined thickness. The set temperatures of the cylinder and the die were 140_150_160_170 °C for the C1_C2_C3_die, the screw rotation speed was 30 rpm, and the take-up speed was adjusted to 4.0 m / min aiming for a film thickness of 30 μm. The various evaluation results are shown in Table 1.

[0083] (Comparative Example 1) Inflation molding was carried out in the same manner as in Example 1 using only Ecovio M2351 without using poly(3-hydroxyalkanoate), and a film was produced. The various evaluation results are shown in Table 1.

[0084] (Comparative Example 2) Inflation molding was carried out in the same manner as in Example 1 except that only P3HB3HH-4 was used as poly(3-hydroxyalkanoate), and a film was produced. The various evaluation results are shown in Table 1.

[0085] (Comparative Example 3) T-die molding was carried out in the same manner as in Example 5 except that the blending ratio of each component was changed as shown in Table 1, and a film was produced. The various evaluation results are shown in Table 1.

[0086]

Table 1

[0087] It can be seen from Table 1 that each film produced in Examples 1 to 5 had high tear strength, low oxygen permeability (high gas barrier property), and good biodegradability.

[0088] On the other hand, the film of Comparative Example 1 did not contain poly(3-hydroxyalkanoate), had high oxygen permeability (low gas barrier property), and insufficient biodegradability. The film of Comparative Example 2 used P3HB3HH in which the 3-hydroxyhexanoate unit was 11 mol% as poly(3-hydroxyalkanoate), and showed a small value for the tear strength, particularly the tear strength in the flow direction. The film of Comparative Example 3 contained both copolymers (A1) and (A2) as poly(3-hydroxyalkanoate), but the proportion of (A2) was as low as 37% by weight, and showed a small value for the tear strength.

Claims

1. A resin composition containing a poly(3-hydroxyalkanoate) resin component (A) and a second resin component (B), wherein the poly(3-hydroxyalkanoate) resin component (A) comprises a copolymer (A1) of a 3-hydroxybutyrate unit and a 3-hydroxyhexanoate unit, in which the content ratio of the 3-hydroxyhexanoate unit is 1 to 6 mol%, and a copolymer (A2) of a 3-hydroxybutyrate unit and a 3-hydroxyhexanoate unit, in which the content ratio of the 3-hydroxyhexanoate unit is 24 to 50 mol%, the proportion of the copolymer (A2) in the total poly(3-hydroxyalkanoate) resin component (A) is 40 to 75% by weight, the second resin component (B) is at least one selected from the group consisting of an aliphatic-aromatic polyester resin, polybutylene succinate, polybutylene succinate adipate, and polylactic acid, and the proportion of the poly(3-hydroxyalkanoate) resin component (A) with respect to the total of the poly(3-hydroxyalkanoate) resin component (A) and the second resin component (B) is 20% by weight or more and 50% by weight or less (however, excluding resin compositions containing 2 to 30 parts by weight of hydrophilic silica with respect to a total of 100 parts by weight of the poly(3-hydroxyalkanoate) resin and polybutylene adipate terephthalate, resin compositions containing 10 to 40 parts by weight of silicate with respect to a total of 100 parts by weight of polylactic acid, the poly(3-hydroxyalkanoate) resin, and the aliphatic-aromatic polyester resin, and resin compositions containing 10 to 50 parts by weight of modified glycerin with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin).

2. The aliphatic-aromatic polyester resin has repeating units derived from an aliphatic dicarboxylic acid, repeating units derived from an aromatic dicarboxylic acid, and repeating units derived from a diol, wherein the aliphatic dicarboxylic acid is at least one selected from the group consisting of succinic acid, adipic acid, azelaic acid, sebacic acid, brassilic acid, pimelic acid, suberic acid, fumaric acid, and itaconic acid, the aromatic dicarboxylic acid is at least one selected from the group consisting of terephthalic acid, isophthalic acid, and furandicarboxylic acid, and the diol is at least one selected from the group consisting of 1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol. The resin composition according to claim 1.

3. The resin composition according to claim 1 or 2, wherein the second resin component (B) contains polybutylene adipate terephthalate as the aliphatic-aromatic polyester resin.

4. The resin composition according to claim 3, wherein the proportion of polybutylene adipate terephthalate in the total of the second resin component (B) is 50 to 100% by weight.

5. The second resin component (B) is polybutylene adipate terephthalate and at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polylactic acid. The resin composition according to claim 3 or 4.

6. The resin composition according to any one of claims 1 to 5, wherein the poly(3-hydroxyalkanoate) resin component (A) has a crosslinked structure.

7. The resin composition according to any one of claims 1 to 6, further containing a plasticizer.

8. A resin film formed from the resin composition according to any one of claims 1 to 7.

9. The resin film according to claim 8, having a thickness of 10 μm or more and 100 μm or less.

10. The resin film according to claim 8 or 9, which is an inflation molded article.

11. The resin film according to any one of claims 8 to 10, wherein the resin film is an agricultural multifilm.

Images