Inflation molded body

Abstract

To provide an inflation molding which contains a poly(3-hydroxyalkanoate)-based resin, enables manufacture with good productivity while suppressing generation of perforation, has good blocking resistance and heat sealability, and has such strength as to be practically usable.SOLUTION: An inflation molding contains a poly(3-hydroxyalkanoate)-based resin component, and a plasticizer. The resin component contains a copolymer (A) having a content ratio of other hydroxyalkanoate unit of 1 mol% or more and less than 5 mol%, a copolymer (B) having the content ratio thereof of 24 mol% or more, and a copolymer (C) having the content ratio thereof 5 mol% or more and less than 24%, as copolymers of a 3-hydroxybutyrate unit and other hydroxyalkanoate unit. A ratio of (C) with respect to a total of the copolymers (A), (B) and (C) is 15 to 45 wt.%, and a content of the plasticizer is 3 pts.wt. or more and less than 10 pts.wt. with respect to 100 pts.wt. of the total of the resin component.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an inflation molded article containing a poly(3-hydroxyalkanoate) resin component.

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. In recent years, microplastics have become a major problem in the marine environment.

[0003] Poly(3-hydroxyalkanoate) resins have excellent seawater degradability and are materials that can solve environmental problems caused by discarded plastics. For example, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), which is one type of poly(3-hydroxyalkanoate) resin, can flexibly control mechanical properties by changing the composition ratio of 3-hydroxyhexanoate.

[0004] However, when the composition ratio of 3-hydroxyhexanoate is increased, the crystallinity decreases, and although the strength of the molded article improves, the productivity of the molded article tends to decrease. In order to achieve the mechanical properties required for the molded article, it was necessary to increase the composition ratio of 3-hydroxyhexanoate until it reached an extremely difficult level for industrial production. Therefore, it has been difficult to obtain a molded article that satisfies both good productivity and strength using poly(3-hydroxyalkanoate) resins.

[0005] In Patent Document 1, in an inflation molded article containing a poly(3-hydroxyalkanoate) resin, in order to achieve both high strength and good productivity, it is disclosed to use at least two types of poly(3-hydroxyalkanoate) resins having different types and / or content ratios of constituent monomers.

[0006] Furthermore, Patent Document 2 describes using a reaction product obtained by melt-kneading a poly(3-hydroxyalkanoate) resin with a specific amount of organic peroxide in order to provide inflation molding with good mechanical properties and productivity as well as blocking resistance. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2022-37396 [Patent Document 2] International Publication No. 2022 / 044836 [Overview of the project] [Problems that the invention aims to solve]

[0008] While the inflation-molded articles described in Patent Document 1 achieve high strength and good productivity, they have problems such as poor blocking resistance, poor opening of the bag when processed into a bag, and insufficient strength when processed into a bag shape by heat sealing, making them unsuitable for practical use.

[0009] Furthermore, while the inflation-molded articles described in Patent Document 2 offer improved blocking resistance, they suffer from a problem in that they are prone to defects such as holes (especially thin films).

[0010] In view of the above situation, the present invention aims to provide an inflation-molded article containing a poly(3-hydroxyalkanoate) resin that can be manufactured with good productivity while suppressing the occurrence of porosity, has good blocking resistance and heat sealability, and has strength that is suitable for practical use. [Means for solving the problem]

[0011] As a result of diligent research to solve the above problems, the present inventors have found that by constructing a poly(3-hydroxybutyrate) resin component from a combination of three copolymers having specific monomer ratios, and by incorporating a specific amount of plasticizer, it is possible to provide an inflation-molded article that can be manufactured with good productivity while suppressing the occurrence of porosity, has good blocking resistance and heat sealability, and has strength suitable for practical use, thus completing the present invention.

[0012] In other words, the present invention relates to an inflation-molded article containing a poly(3-hydroxyalkanoate) resin component and a plasticizer, The aforementioned poly(3-hydroxyalkanoate) resin component is A copolymer (A) of a 3-hydroxybutyrate unit and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 1 mol% or more and less than 5 mol%, A copolymer (B) of a 3-hydroxybutyrate unit and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 24 mol% or more, and The copolymer (C) comprises a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, wherein the content of other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%, The ratio of copolymer (C) to the total of copolymer (A), copolymer (B), and copolymer (C) is 15 to 45% by weight. The present invention relates to an inflation-molded article in which the content of the plasticizer is 3 parts by weight or more and less than 10 parts by weight per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate) resin component. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an inflation-molded article containing a poly(3-hydroxyalkanoate) resin that can be manufactured with good productivity while suppressing the occurrence of porosity, has good blocking resistance and heat sealability, and has strength that is suitable for practical use.

[0014] The inflation molded article according to the present invention can be processed into articles such as bags, gloves, shower caps, aprons, bag containers such as straw packaging bags, bag-shaped protective materials for equipment, storage bags for various documents such as instruction manuals, etc. by fusing a part by heat sealing, and the obtained articles can exhibit strength suitable for actual use.

Brief Description of the Drawings

[0015] [Figure 1] Figure showing the appearance of the bags produced in the examples and comparative examples

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0017] This embodiment relates to an inflation molded article containing a poly(3-hydroxyalkanoate) resin component and a plasticizer.

[0018] (Poly(3-hydroxyalkanoate) resin component) The poly(3-hydroxyalkanoate) resin component includes at least three types of poly(3-hydroxyalkanoate) resins having different content ratios of constituent monomers. Each poly(3-hydroxyalkanoate) resin is a copolymer of a 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) unit and another hydroxyalkanoate unit.

[0019] The other hydroxyalkanoate unit may be a 3-hydroxyalkanoate unit other than the 3HB unit, or may be a hydroxyalkanoate unit other than the 3-hydroxyalkanoate unit (for example, a 4-hydroxyalkanoate unit). Only one type of the other hydroxyalkanoate unit may be included, or two or more types may be included.

[0020] As the poly(3-hydroxyalkanoate) resin, a poly(3-hydroxyalkanoate) resin produced from microorganisms is particularly preferred. In the poly(3-hydroxyalkanoate) resin produced from microorganisms, all 3-hydroxyalkanoate units are contained as (R)-3-hydroxyalkanoate units.

[0021] Specific examples of the poly(3-hydroxyalkanoate) resin include, for example, poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviation: P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxynonanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-3-hydroxyundecanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviation: P3HB4HB), and the like. Particularly, from the viewpoints of productivity and mechanical properties of the inflation molded body, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is particularly preferred.

[0022] The poly(3-hydroxyalkanoate) resin component contains at least the following poly(3-hydroxyalkanoate) resin. A copolymer (A) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, in which the content ratio of the other hydroxyalkanoate unit is 1 mol% or more and less than 5 mol%, Copolymer (B) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 24 mol% or more. Copolymer (C) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%.

[0023] Copolymer (A) is a highly crystalline poly(3-hydroxyalkanoate) resin, while copolymer (B) is a low-crystalline poly(3-hydroxyalkanoate) resin. Copolymer (C) is a medium-crystalline poly(3-hydroxyalkanoate) resin with crystallinity intermediate between copolymer (A) and copolymer (B).

[0024] Generally, highly crystalline poly(3-hydroxyalkanoate) resins have excellent productivity but poor mechanical properties, while low-crystalline poly(3-hydroxyalkanoate) resins have poor productivity but excellent mechanical properties. By using a combination of the three types of resins described above, it becomes possible to produce inflation-molded articles with good productivity while suppressing the occurrence of porosity, and which have good blocking resistance, heat sealability, and strength suitable for practical use.

[0025] The content of other hydroxyalkanoate units in copolymer (A) is 1 mol% or more and less than 5 mol%. From the viewpoint of inflation moldability, the lower limit of the above percentage is preferably 2 mol% or more, and the upper limit is preferably 4 mol% or less.

[0026] The copolymer (A) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0027] The content of other hydroxyalkanoate units in copolymer (B) is 24 mol% or more. From the viewpoint of the strength of the inflated molded article, the lower limit of the above percentage is preferably 26 mol% or more, and more preferably 28 mol% or more. Furthermore, from the viewpoint of the productivity of copolymer (B), the upper limit of the above percentage is preferably 99 mol% or less, more preferably 50 mol% or less, even more preferably 40 mol% or less, and particularly preferably 30 mol% or less.

[0028] The copolymer (B) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0029] The proportion of each copolymer used relative to the total of copolymer (A) and copolymer (B) is not particularly limited, but from the viewpoint of productivity of poly(3-hydroxyalkanoate) resin, the proportion of copolymer (B) relative to the total of copolymer (A) and copolymer (B) is preferably 40% by weight or more, and more preferably 50% by weight or more. Furthermore, from the viewpoint of inflation moldability and practicality when processed into bags, etc., it is preferably 80% by weight or less, and more preferably 70% by weight or less.

[0030] The content of other hydroxyalkanoate units in copolymer (C) is 5 mol% or more and less than 24 mol%. From the viewpoint of inflation moldability, the upper limit of the above percentage is preferably 20 mol% or less, more preferably 15 mol% or less, and even more preferably 10 mol% or less.

[0031] The copolymer (C) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0032] In the inflation-molded article according to this embodiment, the ratio of copolymer (C) to the total of copolymer (A), copolymer (B), and copolymer (C) is 15 to 45% by weight. By setting the ratio of copolymer (C) to 15% by weight or more, blocking resistance can be improved, and the productivity of inflation molding can be improved while suppressing the occurrence of holes. Furthermore, by setting the ratio to 45% by weight or less, the inflation-molded article can be made less prone to cracking and given sufficient strength for practical use. Preferably, the ratio is 20% by weight or more and 40% by weight or less.

[0033] From the viewpoint of achieving both strength and productivity of the inflation-molded article, the average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units to the total monomer units constituting the poly(3-hydroxyalkanoate) resin component is preferably 93 / 7 to 80 / 20 (mol% / mol%), more preferably 92 / 8 to 81 / 19 (mol% / mol%), even more preferably 90 / 10 to 82 / 18 (mol% / mol%), and even more preferably 88 / 12 to 82 / 18 (mol% / mol%).

[0034] The average content ratio of each monomer unit to the total monomer units constituting the poly(3-hydroxyalkanoate) resin component can be determined by methods known to those skilled in the art, for example, by the method described in paragraph

[0047] of International Publication 2013 / 147139. The average content ratio means the molar ratio of each monomer unit to the total monomer units constituting the poly(3-hydroxyalkanoate) resin component, and if the poly(3-hydroxyalkanoate) resin component is a mixture of three types of poly(3-hydroxyalkanoate) resins, it means the molar ratio of each monomer unit contained in the entire mixture.

[0035] The weight-average molecular weight of the poly(3-hydroxyalkanoate) resin component is not particularly limited, but from the viewpoint of achieving both strength and productivity of the blown molded article, it is preferably 200,000 to 2,000,000, more preferably 250,000 to 1,500,000, and even more preferably 300,000 to 1,000,000.

[0036] Furthermore, the weight-average molecular weights of copolymer (A), copolymer (B), and copolymer (C) are not particularly limited. However, from the viewpoint of balancing the strength and productivity of the inflation-molded article, the weight-average molecular weight of copolymer (A) is preferably 200,000 to 1,000,000, more preferably 220,000 to 800,000, and even more preferably 250,000 to 700,000. On the other hand, from the viewpoint of balancing the strength and productivity of the inflation-molded article, the weight-average molecular weight of copolymer (B) is preferably 200,000 to 2,500,000, more preferably 250,000 to 2,300,000, and even more preferably 300,000 to 2,000,000. Furthermore, from the viewpoint of balancing the strength and productivity of the inflation-molded article, the weight-average molecular weight of copolymer (C) is preferably 200,000 to 2,500,000, more preferably 250,000 to 2,300,000, and even more preferably 300,000 to 2,000,000.

[0037] The weight-average molecular weight of the poly(3-hydroxyalkanoate) resin component, copolymer (A), copolymer (B), or copolymer (C) can be measured in polystyrene equivalent using gel permeation chromatography with chloroform solution (HPLC GPC system manufactured by Shimadzu Corporation). For the gel permeation chromatography, any column suitable for measuring weight-average molecular weight should be used.

[0038] The method for producing poly(3-hydroxyalkanoate) resins is not particularly limited and may be by chemical synthesis or by microbial production. Among these, microbial production is preferred. Known methods can be applied to microbial production. For example, known microorganisms that produce copolymers of 3-hydroxybutyrate and other hydroxyalkanoates include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB. In particular, with respect to P3HB3HH, to increase the productivity of P3HB3HH, strains such as Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, p4821-4830 (1997)) into which genes for the P3HA synthase group have been introduced are more preferable, and microbial cells that have accumulated P3HB3HH in their cells by culturing these microorganisms under appropriate conditions are used. In addition to the above, genetically modified microorganisms into which genes related to the synthesis of various poly(3-hydroxyalkanoate) resins may be introduced according to the poly(3-hydroxyalkanoate) resin to be produced, or the culture conditions, including the type of substrate, may be optimized.

[0039] The inflation-molded article according to this embodiment contains a poly(3-hydroxyalkanoate) resin component, but it is preferable that it substantially does not contain a molten mixture of the poly(3-hydroxyalkanoate) resin and an organic peroxide. If the inflation-molded article contains a molten mixture with the organic peroxide, although the blocking resistance can be improved, it is likely to cause holes during inflation molding, which can lead to a decrease in the stability of inflation molding or defects in the inflation-molded article.

[0040] A molten compound of poly(3-hydroxyalkanoate) resin and organic peroxide has a cross-linked structure formed by the reaction of the poly(3-hydroxyalkanoate) resin with the organic peroxide. For further details, please refer to Patent Document 2.

[0041] During the preparation of the aforementioned molten compound, the crosslinking reaction proceeds unevenly, making it prone to generating foreign matter. This can potentially cause holes to form during inflation molding.

[0042] Here, "substantially free of molten compound of poly(3-hydroxyalkanoate) resin and organic peroxide" means that the proportion of the molten compound in the total poly(3-hydroxyalkanoate) resin component contained in the blown molded article is 10% by weight or less. The proportion is preferably 5% by weight or less, and more preferably 1% by weight or less. The lower limit of the proportion may be 0% by weight.

[0043] However, even in the case of reaction products between poly(3-hydroxyalkanoate) resins and organic peroxides, it is presumed that the occurrence of pore formation can be avoided if the crosslinking reaction proceeds uniformly.

[0044] The aforementioned organic peroxides are not particularly limited, but examples include 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, and 1,1,3,3-tetramethylbutyl peroxydioxide. Examples include oxy-2-ethylhexanoate, disuccinate peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxy2-ethylhexyl carbonate, t-butylperoxyisopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyacetate, t-butylperoxybenzoate, t-amylperoxy,3,5,5-trimethylhexanoate, 2,2-bis(4,4-di-t-butylperoxycyclohexy)propane, and 2,2-di-t-butylperoxybutane. One type of organic peroxide may be used alone, or two or more types may be used in combination.

[0045] The amount of organic peroxide used is not particularly limited, but for example, it may be about 0.01 to 0.5 parts by weight per 100 parts by weight of the poly(3-hydroxyalkanoate) resin reacted with the organic peroxide.

[0046] The inflation-molded article according to this embodiment contains a plasticizer in addition to the poly(3-hydroxyalkanoate) resin component. By incorporating a plasticizer, the productivity of inflation molding can be improved, blocking resistance can be enhanced, and the inflation-molded article can be given strength that is suitable for practical use.

[0047] The aforementioned plasticizer is not particularly limited, but from the viewpoint of compatibility with poly(3-hydroxyalkanoate) resin components, it is preferable to use an ester compound having an ester bond in the molecule.

[0048] Examples of ester compounds that can be used as plasticizers include modified glycerin compounds, dibasic acid ester compounds, adipic acid ester compounds, polyether ester compounds, benzoic acid ester compounds, citrate ester compounds, isosorbide ester compounds, and polycaprolactone compounds. Among these, modified glycerin compounds, dibasic acid ester compounds, adipic acid ester compounds, polyether ester compounds, or isosorbide ester compounds are preferred, and modified glycerin compounds are particularly preferred. Furthermore, one of the ester compounds can be used alone, or two or more can be used in combination. When two or more are used in combination, the mixing ratio of the ester compounds can be adjusted as appropriate.

[0049] As the modified glycerin-based compound, glycerin ester compounds are preferred. As the glycerin ester compound, any of glycerin monoester, diester, or triester can be used, but from the viewpoint of compatibility with poly(3-hydroxyalkanoate) resin components, glycerin triesters are preferred. Among glycerin triesters, glycerin diacetone monoester is particularly preferred. Specific examples of glycerin diacetone monoesters include glycerin diacetone monolaurate, glycerin diacetone monooleate, glycerin diacetone monostearate, glycerin diacetone monocaprylate, and glycerin diacetone monodecanoate. Examples of the modified glycerin-based compound include Riken Vitamin Co., Ltd.'s "Rikemar" PL series and "BIOCIZER".

[0050] Specific examples of dibasic acid ester compounds include dibutyl adipate, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis(2-ethylhexyl) azelate, dibutyl sebacate, bis(2-ethylhexyl) sebacate, diethyl succinate, and mixed dibasic acid ester compounds.

[0051] Examples of adipic acid ester compounds include diethylhexyl adipate, dioctyl adipate, and diisononyl adipate.

[0052] Examples of polyether ester compounds include polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate.

[0053] As for the ester compounds, modified glycerin compounds are preferred due to their cost-effectiveness, versatility, and high biomass content. Glycerin triesters are more preferred, glycerin diacetone monoesters are even more preferred, and glycerin diacetone monolaurates are particularly preferred from the viewpoint of food contact.

[0054] The amount of plasticizer added is 3 parts by weight or more and less than 10 parts by weight per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate) resin component. By adding 3 parts by weight or more of plasticizer, the productivity of inflation molding is improved, blocking resistance is enhanced, and the inflation molded article is given sufficient strength for practical use. Furthermore, by adding less than 10 parts by weight, the productivity of inflation molding and heat sealability can be improved.

[0055] The lower limit of the amount of plasticizer blended is preferably 3.5 parts by weight or more. It may also be 4 parts by weight or more. The upper limit is preferably 9 parts by weight or less, more preferably 8 parts by weight or less, and even more preferably 7.5 parts by weight or less. It may also be 6 parts by weight or less.

[0056] (Other resins) The inflation-molded article according to this embodiment may contain other resins besides poly(3-hydroxyalkanoate) resins, to the extent that the effects of the invention are not impaired. Examples of such other resins include aliphatic polyester resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate, polybutylene sebacate terephthalate, and polybutylene azelate terephthalate. The article may contain only one of these other resins, or two or more.

[0057] The content of the other resins is not particularly limited, but is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 10 parts by weight or less, based on 100 parts by weight of the total amount of poly(3-hydroxyalkanoate) resin components. The lower limit of the content of the other resins is not particularly limited and may be 0 parts by weight.

[0058] (silica) The inflation-molded article according to this embodiment may further contain silica in order to obtain an improvement in its mechanical properties.

[0059] The type of silica is not particularly limited, but from the viewpoint of versatility, synthetic amorphous silica produced by a dry or wet method is preferred. Furthermore, silica that has been treated with either hydrophobic or non-hydrophobic methods can be used, and one type can be used alone, or two or more types can be used in combination.

[0060] The silica is preferably one with an adsorbed water content of 0.5% by weight or more and 7% by weight or less. The adsorbed water content can be measured, for example, using an electromagnetic scale MX-50 manufactured by Kensei Kogyo Co., Ltd., and the volatile content at 160°C is taken as the adsorbed water content. If the adsorbed water content is greater than 7% by weight, the cohesive force of the water adsorbed on the silica surface and between particles makes dispersion difficult, which can result in fisheyes and other appearance defects during inflation molding. Conversely, if it is less than 0.5% by weight, this small amount of remaining water between particles forms a cross-linking liquid film, creating a large bonding force due to surface tension, which tends to make separation and dispersion extremely difficult.

[0061] The average primary particle diameter of the silica is not particularly limited as long as it can improve the mechanical properties of the inflation molded body, is less likely to cause cosmetic defects such as fisheyes, and does not significantly impair transparency. However, it is preferably 0.001 to 0.1 μm, and particularly preferably 0.005 to 0.05 μm, as this provides an easy way to improve mechanical properties and maintains excellent transparency. The average primary particle diameter is determined by arithmetic mean of the diameters of 50 or more arbitrary primary particles observed using a transmission electron microscope (TEM).

[0062] The amount of silica is not particularly limited, but it is preferably 1 to 12 parts by weight per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate) resin component. If the amount is 1 part by weight or more, a sufficient improvement effect on the mechanical properties due to the silica can be observed when compounded with the poly(3-hydroxyalkanoate) resin component. If the amount is 12 parts by weight or less, the silica can be dispersed well. The amount of silica is more preferably 2 parts by weight or more, and even more preferably 4 parts by weight or more. It is also more preferably 11 parts by weight or less, and even more preferably 10 parts by weight or less.

[0063] To improve the dispersibility of the silica, it is preferable to use the silica in combination with a dispersion aid.

[0064] Examples of the aforementioned dispersing aids include glycerin ester compounds, adipic acid ester compounds, polyether ester compounds, phthalate ester compounds, isosorbide ester compounds, and polycaprolactone compounds. Of these, modified glycerin compounds such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate are preferred because they have excellent affinity for resin components and do not bleed easily; 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. Furthermore, those containing a large amount of biomass-derived components are particularly preferred because they can increase the overall biomass content of the composition. Examples of such dispersing aids include Riken Vitamin Co., Ltd.'s acetylated monoglyceride BIOCIZER and PL series, and ROQUETTE's Polysorb series. Dispersing agents can be used individually or in combination of two or more types.

[0065] The amount of the dispersion aid is not particularly limited, but is preferably 0.1 to 20 parts by weight per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate) resin component. If the amount is 0.1 parts by weight or more, the silica can fully exhibit its function as a dispersion aid, and when compounded with the poly(3-hydroxyalkanoate) resin component, the silica can sufficiently improve the mechanical properties. If the amount is 20 parts by weight or less, bleed-out can be suppressed. The 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. It is also more preferably 10 parts by weight or less, and even more preferably 5 parts by weight or less.

[0066] (Additives) The inflation-molded article according to this embodiment may contain additives to the extent that they do not impair the effects of the invention. Examples of additives that can be used, depending on the purpose, include crystallization nucleating agents, lubricants, antistatic agents, flame retardants, conductive agents, heat insulating agents, crosslinking agents, antioxidants, ultraviolet absorbers, colorants, inorganic fillers, organic fillers, hydrolysis inhibitors, and the like. Biodegradable additives are particularly preferred.

[0067] Examples of crystallization nucleating agents include pentaerythritol, orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride. Among these, pentaerythritol is preferred because it is particularly effective in promoting the crystallization of poly(3-hydroxyalkanoate) resin components. The amount of 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, per 100 parts by weight of the total amount of poly(3-hydroxyalkanoate) resin components. Furthermore, 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 depending on the purpose.

[0068] Examples of lubricants include behenamide, oleamide, erucamide, stearamide, palmitamide, N-stearylbehenamide, N-stearylerucamide, ethylenebisstearate, ethylenebisoleamide, ethylenebiserucamide, ethylenebislaurylamide, ethylenebiscaprate, p-phenylenebisstearate, and polycondensates of ethylenediamine, stearic acid, and sebacic acid. Among these, behenamide and erucamide are preferred because they have particularly excellent lubricating effects on poly(3-hydroxyalkanoate) resin components. The amount of 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 even more preferably 0.1 to 1.5 parts by weight, per 100 parts by weight of the total amount of poly(3-hydroxyalkanoate) resin components. Furthermore, one type of lubricant may be used, or two or more types may be used, and the ratio of use can be adjusted as appropriate depending on the purpose.

[0069] (Thickness of the inflated molded body) The thickness of the inflation molded article is not particularly limited, but is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less, and even more preferably 15 μm or more and 60 μm or less.

[0070] (Method for manufacturing an inflated molded body) The method for obtaining the blend of copolymer (A), copolymer (B), and copolymer (C) is not particularly limited and may be by microbial production or by chemical synthesis. Alternatively, the blend may be obtained by melt-kneading two or more resins using an extruder, kneader, Banbury mixer, rolls, etc., or by dissolving two or more resins in a solvent, mixing, and drying. Furthermore, multiple of the above methods may be combined.

[0071] The inflation-molded article according to this embodiment can be manufactured by melt-kneading resin components and various additives as needed, and then performing inflation molding. The aforementioned inflation molding refers to a molding method in which a molten resin composition is extruded in a tubular shape from an extruder equipped with a cylindrical die at its tip, and immediately afterward, gas is blown into the tube to inflate it into a balloon shape, thereby forming a tubular single-layer or multi-layer film. The method of inflation molding is not particularly limited, but it can be carried out using, for example, a general inflation molding machine used when molding thermoplastic resins into films. A general inflation molding machine, in the case of molding a single-layer film, refers to one in which a single cylindrical die is attached to one single-screw extruder. In the case of molding a multi-layer film, it refers to a machine that can pour molten resin from multiple extruders into one cylindrical die according to the type of resin used, and laminate each resin within the die. The single-screw extruder only needs to be capable of melting and kneading the raw resin that is fed in, and obtaining a constant discharge while maintaining the desired temperature. The screw shape of the single-screw extruder is not particularly limited, but one equipped with a mixing element is preferable from the viewpoint of kneading ability. Furthermore, the structure of the cylindrical die is not particularly limited and is designed appropriately to suit single-layer and laminated films, but among them, spiral mandrel dies are preferred because they produce less weld and make it easier to achieve uniform thickness.

[0072] The molding temperature in inflation molding is not particularly limited as long as it is a temperature at which the resin can be properly melted, but for example, 135 to 200°C is preferred. Here, the molding temperature refers to the resin temperature from the extruder to the point where it is ejected from the die. The resin temperature can generally be measured by a thermometer installed in an adapter, for example.

[0073] The take-up rate in inflation molding is determined by the film thickness, width, and resin discharge rate of the molded body, but it can be adjusted within a range that maintains balloon stability. Generally, 1 to 50 m / min is preferred.

[0074] In inflation molding, an air ring blown from the outside of the balloon can be used to solidify the extruded molten resin and stabilize the balloon. A preferred air ring structure is a slit type, which has multiple annular slits from which air is blown, and chambers between each slit promote balloon stabilization.

[0075] After inflation molding, the process may include steps such as taking the tubular molded film, folded on pinch rolls, to a winding roll, blowing air into the interface of the folded film on the pinch rolls to easily separate the folded molded film after winding, and cutting the film according to the application during the take-up process. Cutting methods include cutting both ends of the folded tubular molded film in the width direction to form two films, or hot cutting the tubular molded film in the width direction and fusing it by heat sealing to form a bag-shaped film. It may also include a step of blowing air into the interface of the folded film just before cutting to make it easier to cut. It may also include a step of folding both ends of the folded tubular film inward, a so-called gusset fold. Furthermore, after folding on pinch rolls, it may be printed on the film surface before winding, and corona treatment may be performed on the film surface before printing to further improve print adhesion. The printing method is not particularly limited, but examples include gravure printing and flexographic printing.

[0076] Because the inflation-molded body 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 products, packaging, automobiles, building materials, and other fields. For example, it can be used for garbage bags, shopping bags, vegetable and fruit packaging bags, pillow packaging, delivery bags, bags for gloves, shower caps, aprons, straw packaging bags and other bag containers, bag-shaped protective materials for equipment, storage bags for various documents such as instruction manuals, agricultural mulch films, forestry fumigation sheets, binding tapes including flat yarn, root wrapping films for plants, diaper backsheets, packaging sheets, shopping bags, drainer bags, and other compost bags.

[0077] In particular, the inflation-molded article according to this embodiment has good heat-sealability and can therefore be suitably used in a form that includes a portion fused by heat sealing. Although there are no particular limitations on such a form, the inflation-molded article according to this embodiment has good heat-sealability, good blocking resistance (opening ability), and strength that is sufficient for practical use, so it can be particularly suitably used as various bags, bag containers such as gloves, shower caps, aprons, and straw packaging bags, bag-shaped protective materials for equipment, and storage bags for various documents such as instruction manuals.

[0078] The heat sealing method refers to a processing method in which an inflated molded body is pressed together under heat. By fusing a portion of the inflated molded body through heat sealing, the inflated molded body can be secondarily processed into the shape of bags, bags for gloves, shower caps, aprons, straw packaging bags and other bag containers, protective materials in the form of bags for equipment, and storage bags for various documents such as instruction manuals. The heat sealing temperature is not particularly limited and can be set appropriately by those skilled in the art, but for example, it may be around 120 to 250°C. Similarly, the heat sealing pressure is not particularly limited and can be set appropriately by those skilled in the art, but for example, it may be 0.1 MPa or higher.

[0079] The following sections list preferred embodiments of this disclosure, but the present invention is not limited to these sections. [Item 1] An inflation-molded article containing a poly(3-hydroxyalkanoate) resin component and a plasticizer, The aforementioned poly(3-hydroxyalkanoate) resin component is A copolymer (A) of a 3-hydroxybutyrate unit and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 1 mol% or more and less than 5 mol%, A copolymer (B) of a 3-hydroxybutyrate unit and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 24 mol% or more, and The copolymer (C) comprises a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, wherein the content of other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%, The ratio of copolymer (C) to the total of copolymer (A), copolymer (B), and copolymer (C) is 15 to 45% by weight. An inflation-molded article in which the content of the plasticizer is 3 parts by weight or more and less than 10 parts by weight per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate) resin component. [Item 2] An inflation-molded article as described in item 1, which substantially does not contain a molten compound of poly(3-hydroxyalkanoate) resin and organic peroxide. [Item 3] The inflation molded article according to item 1 or 2, wherein the average content of the other hydroxyalkanoate units in relation to the total monomer units constituting the poly(3-hydroxyalkanoate) resin component is 10 to 18 mol%. [Item 4] The inflation molded article according to any one of items 1 to 3, wherein the other hydroxyalkanoate unit is a 3-hydroxyhexanoate unit. [Item 5] The inflation-molded article according to any one of items 1 to 4, wherein the plasticizer is a modified glycerol-based compound. [Item 6] The inflation-molded article according to item 5, wherein the modified glycerin compound comprises at least one selected from the group consisting of glycerin diacetomonolaurate, glycerin diacetomonolate, glycerin diacetomonostearate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate. [Item 7] The inflation molded body according to any one of items 1 to 6, wherein the inflation molded body includes a portion that has been fused by heat sealing. [Item 8] The inflation molded body according to item 7, wherein the inflation molded body is a bag. [Item 9] The inflation-molded body according to any one of items 1 to 8, wherein the film thickness of the inflation-molded body is 10 to 100 μm. [Examples]

[0080] The present invention will be specifically described below with reference to examples, but the technical scope of the present invention is not limited by these examples.

[0081] The following raw materials were used in the examples and comparative examples. P3HB3HH-1:P3HB3HH (Average content ratio 3HB / 3HH = 97.2 / 2.8 (mol% / mol%), weight-average molecular weight is 620,000 g / mol) P3HB3HH-2: P3HB3HH (Average content ratio 3HB / 3HH = 71.8 / 28.2 (mol% / mol%), weight-average molecular weight is 620,000 g / mol) P3HB3HH-3:P3HB3HH (Average content ratio 3HB / 3HH = 94 / 6 (mol% / mol%), weight-average molecular weight is 400,000 g / mol)

[0082] (organic peroxide) NOF Corporation's Perbutyl I (t-butyl peroxyisopropyl carbonate, 1-minute half-life temperature: 159°C)

[0083] (Plasticizer) Glycerin diacetone monolaurate (manufactured by Riken Vitamin Co., Ltd., Biocizer)

[0084] (Crystallizing agent) Pentaerythritol (manufactured by Mitsubishi Chemical Corporation, Neurizer P)

[0085] (Lubricant) Erucic acid amide, behenic acid amide

[0086] The following evaluations were performed for each example and comparative example. (Inflation moldability) We measured the maximum take-up speed at which the balloon could stably perform inflation molding while maintaining a fold width of 400 mm and an average thickness of 30 μm for the inflation film. Furthermore, regardless of the fold width, inflation molding was performed while maintaining a take-up speed of 10 m / min or more, with an average film thickness of 25 μm, and the presence or absence of holes in the resulting inflation film was evaluated.

[0087] <Productivity> ○: Maximum take-up speed is 10m / min or more, and the variation in fold width within a 20m length of obtained film is less than 20mm. ×: Other than the above The aforementioned fold width refers to the width of the double film when the balloon-shaped molded film extruded from the die is folded into a double film by passing it through a cooling roll. Note that if the variation in fold width becomes large, the variation in thickness will also become large, making it difficult to maintain the cylindrical shape (i.e., it becomes difficult to stably form a balloon).

[0088] <Hole> ○: A hole has formed in the film. ×: No holes were created in the film. When holes occur, air escapes from inside the tube, causing the width to fluctuate, making it difficult to maintain the stability of the inflation molding process. Furthermore, holes in the manufactured film are considered defects and are evaluated as poor quality.

[0089] (bag processability) The bottom of a tubular film roll obtained by inflation molding is heat-sealed to one or both ends, and in some cases, punched out to create handles. These are then processed into shapes such as bags, gloves, shower caps, aprons, straw packaging bags, protective bags for equipment, and storage bags for various documents such as instruction manuals. These processed products are required to open easily. Furthermore, it is necessary to efficiently achieve sufficient heat-seal strength to hold the contents inside the processed product. From these perspectives, the ease of opening and heat-sealing properties were evaluated.

[0090] <Opening angle> From the rolled-up tubular inflation film, a long sample of double-layered film measuring 5 cm wide x 15 cm long was cut out. This double-layered film was evaluated by rubbing it between the thumb and index finger to see if it would open or close. 〇: Open ×: Do not open

[0091] <Heat sealability> Bag making was performed using an inflation film with an average thickness of 50 μm, and the heat seal strength was evaluated according to the evaluation method specified in JIS Z 1711. ○: Can produce bags at a speed of 25 bags / minute or more, and achieve a seal strength of 8N / 15mm or more. △: Capable of producing bags at a speed of 20 bags / minute or more, and achieving a seal strength of 8N / 15mm or more. ×: None of the above are satisfied.

[0092] (Evaluation of the practicality of the bag) The practical usability evaluation of the bags was conducted on the examples and comparative examples that received a "○" rating for both the productivity of inflation molding and the ease of opening the bag. Using the resin formulations of each example and comparative example, film rolls with a folded width of 450 mm and an average thickness of 50 μm were produced by inflation molding. The obtained inflation films were processed into bags with the specifications shown in Figure 1. The obtained bags were subjected to a vibration test using a vibration testing machine with a 3kg weight placed inside, applying a vibration load equivalent to one hour of walking (100 times / min, vertical amplitude ±5cm) to check whether the bags would break. Passed: The bag was not destroyed during the vibration test. Failure: The bag was destroyed during the vibration test.

[0093] Example 1 (Method for manufacturing resin film) P3HB3HH-1, P3HB3HH-2, P3HB3HH-3, and each additive were mixed in the proportions shown in Table 1 using a co-meshing twin-screw extruder (Toshiba Machine Co., Ltd.: TEM26ss) at a set temperature of 120°C to 170°C and a screw rotation speed of 150 rpm. After obtaining a molten mixture by strand cutting, an inflation film was produced using an inflation molding machine (Hokushin Sangyo Co., Ltd.) which had a die with a 100 mm diameter cylindrical die slip attached to an extruder with a single-screw L / D=32. We evaluated the inflation moldability, bag processability, and bag practicality, and the results are shown in Table 1.

[0094] Examples 2-4 A molten compound was prepared in the same manner as in Example 1, except that the proportions of the resin or each additive were changed as shown in Table 1. Then, an inflation film was prepared in the same manner, and each evaluation was performed. The evaluation results are shown in Table 1.

[0095] Comparative Examples 1-5 A molten compound was prepared in the same manner as in Example 1, except that the proportions of the resin or each additive were changed as shown in Table 1. Then, an inflation film was prepared in the same manner, and each evaluation was performed. The evaluation results are shown in Table 1.

[0096] Comparative Example 6 Except for adding organic peroxides in the proportions shown in Table 1, a molten compound was prepared in the same manner as in Comparative Example 1, and then an inflation film was prepared in the same manner, and each evaluation was performed. The evaluation results are shown in Table 1.

[0097] [Table 1]

[0098] Table 1 shows the following: Examples 1-4 yielded good results in all evaluations, including inflation molding productivity, perforation, bag processability (opening and heat sealability), and bag practicality. On the other hand, Comparative Examples 1-6 did not yield good results in any of the evaluations. Comparative Examples 1 and 6 had low amounts of P3HB3HH-3, which corresponds to copolymer (C), while Comparative Examples 2-5 either did not contain plasticizers, or contained low or high amounts of plasticizers. [Explanation of Symbols]

[0099] 10 bags 11. Punched handle

Claims

1. An inflation-molded article containing a poly(3-hydroxyalkanoate) resin component and a plasticizer, The aforementioned poly(3-hydroxyalkanoate) resin component is A copolymer (A) of a 3-hydroxybutyrate unit and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 1 mol% or more and less than 5 mol%, A copolymer (B) of a 3-hydroxybutyrate unit and other hydroxyalkanoate units, wherein the content of other hydroxyalkanoate units is 24 mol% or more, and The copolymer (C) comprises a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, wherein the content of other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%, The ratio of copolymer (C) to the total of copolymer (A), copolymer (B), and copolymer (C) is 15 to 45% by weight. The content of the plasticizer is 3 parts by weight or more and less than 10 parts by weight per 100 parts by weight of the total amount of the poly(3-hydroxyalkanoate) resin component. The inflation-molded body includes portions that have been fused together by heat sealing.

2. The inflation molded article according to claim 1, which substantially does not contain a molten mixture of poly(3-hydroxyalkanoate) resin and organic peroxide.

3. The inflation molded article according to claim 1 or 2, wherein the average content of the other hydroxyalkanoate units in relation to the total monomer units constituting the poly(3-hydroxyalkanoate) resin component is 10 to 18 mol%.

4. The inflation-molded article according to claim 1 or 2, wherein the other hydroxyalkanoate unit is a 3-hydroxyhexanoate unit.

5. The inflation-molded article according to claim 1 or 2, wherein the plasticizer is a modified glycerin-based compound.

6. The inflation molded article according to claim 5, wherein the modified glycerin compound comprises at least one selected from the group consisting of glycerin diacetomonolaurate, glycerin diacetomonolate, glycerin diacetomonostearate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate.

7. The inflation molded body according to claim 1 or 2, wherein the inflation molded body is a bag.

8. The inflation-molded body according to claim 1 or 2, wherein the film thickness of the inflation-molded body is 10 to 100 μm.

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