Thermoplastic resin composition

Abstract

Provided is a thermoplastic resin composition comprising 40-90 parts by weight of a thermoplastic resin (A), and 10-60 parts by weight [provided that the total amount of (A) and (B) being100 parts by weight] of crosslinked resin particles (B) containing a polyhydroxyalkanoate-based resin and having a gel fraction of 50% or higher. The polyhydroxyalkanoate-based resin may be a poly(3-hydroxyalkanoate)-based resin. The crosslinked resin particles (B) may have a volume average particle size of 0.1-10 µm. The thermoplastic resin composition can be formed into a molded body.

Description

thermoplastic resin composition

[0001] The present invention relates to a thermoplastic resin composition.

[0002] Plastic waste is a burden on the global environment, affecting ecosystems, emitting harmful gases when burned, and contributing to global warming due to the large amount of heat generated by combustion. Biodegradable plastics are being actively developed as a material that can solve these problems.

[0003] Patent Document 1 describes a biodegradable and environmentally friendly thermoplastic resin composition that is obtained by blending 0.1 to 20 parts by weight of poly(3-hydroxyalkanoate) particles having an average particle size of 300 μm or less with 100 parts by weight of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0004] Japanese Patent Application Laid-Open No. 2004-161802

[0005] The technique of blending poly(3-hydroxyalkanoate) particles into a thermoplastic resin, as described in Patent Document 1, can improve the flexibility of the thermoplastic resin, but does not contribute to improving the impact resistance of the thermoplastic resin.

[0006] In view of the above-mentioned current situation, an object of the present invention is to provide a thermoplastic resin composition having improved mechanical strength such as impact strength.

[0007] As a result of extensive research, the present inventors have discovered that mechanical strength such as impact strength can be improved by blending crosslinked resin particles made of a polyhydroxyalkanoate resin and satisfying a specific gel fraction with a thermoplastic resin, and have thus completed the present invention.

[0008] Specifically, the present invention relates to a thermoplastic resin composition comprising 40 to 90 parts by weight of a thermoplastic resin (A) and 10 to 60 parts by weight of crosslinked resin particles (B) containing a polyhydroxyalkanoate resin and having a gel fraction of 50% or more (where the total amount of (A) and (B) is 100 parts by weight). The present invention also relates to a molded article of the thermoplastic resin composition. Furthermore, the present invention also relates to a modifier for a thermoplastic resin comprising crosslinked resin particles (B) containing a polyhydroxyalkanoate resin and having a gel fraction of 50% or more.

[0009] According to the present invention, a thermoplastic resin composition having improved mechanical strength, such as impact strength, can be provided. The thermoplastic resin composition according to the present invention contains crosslinked resin particles composed of a polyhydroxyalkanoate resin, and is therefore advantageous from the viewpoint of biodegradability. The crosslinked resin particles can be used as a modifier or impact modifier for thermoplastic resins.

[0010] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0011] The thermoplastic resin composition according to the present embodiment contains at least a thermoplastic resin (A) and crosslinked resin particles (B) containing a polyhydroxyalkanoate resin and having a gel fraction of 50% or more. In the thermoplastic resin composition, the impact strength of the thermoplastic resin (A) is improved, and the thermoplastic resin composition exhibits good impact resistance. First, the crosslinked resin particles (B) will be described.

[0012] <Crosslinked Resin Particles (B)> The crosslinked resin particles (B) are particles composed of a polyhydroxyalkanoate-based resin as a main resin component. Hereinafter, the polyhydroxyalkanoate-based resin may be abbreviated as "PHA."

[0013] <PHA> "PHA" is a general term for polymers having hydroxyalkanoic acid as a monomer unit, and is generally biodegradable. PHA is an aliphatic polyester, preferably a polyester not containing an aromatic ring.

[0014] The PHA is not particularly limited, but examples thereof include polyglycolic acid, poly(3-hydroxyalkanoate)-based resins, and poly(4-hydroxyalkanoate)-based resins. Only one type of PHA may be used, or two or more types may be used in combination. Of these, poly(3-hydroxyalkanoate)-based resins are preferred. Hereinafter, poly(3-hydroxyalkanoate)-based resins may be abbreviated as "P3HA."

[0015] The P3HA has the formula: [—CHR—CH ２3-hydroxyalkanoic acid repeating units represented by the formula: —CO—O— (wherein R is C ｎ H ２ｎ＋１ where n is an integer of 1 to 15.) as an essential repeating unit. The P3HA preferably contains 50 mol % or more, and more preferably 70 mol % or more, of the total monomer repeating units (100 mol %) of the 3-hydroxyalkanoic acid repeating units.

[0016] P3HA is not particularly limited, but examples thereof include poly(3-hydroxybutyrate) (abbreviation: P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), etc. Only one type of P3HA may be used, or two or more types may be used in combination.

[0017] P3HA can be produced by microorganisms. Such microbially produced P3HA is usually P3HA composed only of D-form (R-form) hydroxyalkanoic acid repeating units. Among microbially produced P3HAs, P3HB and P3HB3HH are preferred, with P3HB3HH being more preferred, due to ease of industrial production.

[0018] When P3HA contains 3-hydroxybutanoic acid (3HB) repeating units, from the viewpoint of the balance between flexibility and strength, the composition ratio of 3HB repeating units in all monomer repeating units (100 mol%) is preferably 60 to 99 mol%, more preferably 65 to 97 mol%, and even more preferably 67 to 95 mol%. Having a composition ratio of 3HB repeating units of 60 mol% or more makes the crosslinked resin particles (B) easier to handle. On the other hand, having a composition ratio of 3HB repeating units of 99 mol% or less tends to ensure the flexibility of the crosslinked resin particles (B). The monomer composition ratio of P3HA can be measured by gas chromatography or the like (see, for example, WO 2014 / 020838). Two or more types of P3HA having different composition ratios of 3HB repeating units may be used in combination.

[0019] The microorganism that produces P3HA is not particularly limited as long as it has the ability to produce P3HA. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other naturally occurring microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus are known. In these microorganisms, P3HB accumulates intracellularly.

[0020] Furthermore, Aeromonas caviae, a P3HB3HH-producing bacterium, is known as a producer of copolymers of 3HB and other hydroxyalkanoates. In particular, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)) into which genes encoding P3HA synthases have been introduced is preferred to increase the productivity of P3HB3HH. Microbial cells obtained by culturing such microorganisms under appropriate conditions and accumulating P3HA within the cells are used. In addition to the above, genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced may be used depending on the P3HA to be produced, or the culture conditions, including the type of substrate, may be optimized.

[0021] The molecular weight of the PHA is not particularly limited, but the weight-average molecular weight is preferably 50,000 to 3,000,000, more preferably 100,000 to 2,000,000, and more preferably 150,000 to 1,500,000. By setting the weight-average molecular weight to 50,000 or more, it is possible to avoid the tendency for the crosslinked resin particles to have low strength or to be sticky due to low molecular weight components. On the other hand, PHAs with a weight-average molecular weight exceeding 3,000,000 may be difficult to produce or handle for the purposes of the present invention. The weight-average molecular weight is measured before the PHA is crosslinked.

[0022] The weight-average molecular weight can be measured using gel permeation chromatography (GPC) (Shimadzu Corporation's "High Performance Liquid Chromatograph 20A System"), using polystyrene gel (Showa Denko K.K.'s "K-G 4A" or "K-806M" or the like) as a column, and chloroform as a mobile phase, and can be determined as a molecular weight converted into polystyrene. In this case, a calibration curve can be prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. As the column for the GPC, a column appropriate for measuring the molecular weight can be used.

[0023] <Gel fraction> The crosslinked resin particles (B) have a crosslinked structure in which molecular chains of PHA are bonded to each other. Since the crosslinked resin particles (B) have a certain amount or more of such crosslinked structure, they exhibit a high gel fraction, specifically, a gel fraction of 50% or more. By exhibiting such a high gel fraction, the effect of improving the mechanical strength, such as impact strength, of the thermoplastic resin (A) can be enhanced.

[0024] From the viewpoint of improving impact strength, the gel fraction value is preferably 60% or more, more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more. It may also be 85% or more, or even 90% or more. The upper limit of the gel fraction is not particularly limited as long as it is 100% or less. From the viewpoint of production efficiency of the crosslinked resin particles (B) and improving impact strength, it is preferably 99.5% or less, more preferably 99% or less. It may also be 98% or less, 97% or less, or 96% or less.

[0025] The gel fraction is a value measured as follows. A dried product of crosslinked resin particles (B) is added to chloroform so that the concentration becomes 0.7% by weight, and the mixture is dissolved at 60°C for 30 minutes to obtain a chloroform solution. After that, the mixture is left to stand at room temperature for 3 hours, and the chloroform solution is filtered through a membrane filter with a pore size of 0.45 µm. The gel remaining on the filter is dried, and the weight of the filter is measured, and the gel fraction is calculated using the following formula: Gel fraction = (weight of filter including dried gel - weight of filter only) / weight of crosslinked resin particles used for measurement x 100 (%)

[0026] <Average particle size> The crosslinked resin particles (B) preferably have a volume average particle size in the range of 0.1 μm to 10 μm. Such a particle size can further improve the mechanical strength, such as impact strength, of the thermoplastic resin (A). From the viewpoint of practical use, the lower limit of the particle size is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. Furthermore, from the viewpoint of productivity (such as PHA production and crosslinking treatment), the upper limit of the particle size is preferably 8 μm or less, more preferably 5 μm or less. However, melt-kneading the crosslinked resin particles (B) with the thermoplastic resin (A) may cause the original shape of the crosslinked resin particles (B) to be destroyed, resulting in a decrease in the volume average particle size.

[0027] The volume average particle diameter is a value measured when the crosslinked resin particles (B) are dispersed in an aqueous solvent. A general-purpose measuring device can be used as the measuring device, and an example of such a device is Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.

[0028] <Peroxide> The crosslinking type of the crosslinked resin particles (B) is not particularly limited, but it is preferable that the crosslinking is performed using a peroxide. When a peroxide is used, radicals generated by decomposition of the peroxide act on PHA molecules to directly bond PHA molecular chains to each other, thereby forming the crosslinked structure.

[0029] The peroxide may be an organic peroxide or an inorganic peroxide, but is preferably an organic peroxide because it can increase the gel fraction more efficiently.

[0030] As the organic peroxide, it is preferable to use at least one selected from the group consisting of diacyl peroxides, alkyl peroxy esters, dialkyl peroxides, hydroperoxides, peroxyketals, peroxycarbonates, and peroxydicarbonates, taking into consideration the heating temperature and time during the crosslinking treatment.

[0031] Specific examples of such organic peroxides include butyl peroxy neododecanoate, octanoyl peroxide, dilauroyl peroxide, succinic peroxide, a mixture of toluoyl peroxide and benzoyl peroxide, benzoyl peroxide, bis(butylperoxy)trimethylcyclohexane, butyl peroxylaurate, dimethyldi(benzoylperoxy)hexane, bis(butylperoxy)methylcyclohexane, bis(butylperoxy)cyclohexane, and butylperoxybenzo ester, butyl bis(butylperoxy)valerate, dicumyl peroxide, di-t-hexyl peroxide, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxymethyl monocarbonate, t-pentylperoxymethyl monocarbonate, t-hexylperoxymethyl monocarbonate, t-heptylperoxymethyl monocarbonate, t-octylperoxymethyl monocarbonate, 1 , 1,3,3-tetramethylbutylperoxymethyl monocarbonate, t-butylperoxyethyl monocarbonate, t-pentylperoxyethyl monocarbonate, t-hexylperoxyethyl monocarbonate, t-heptylperoxyethyl monocarbonate, t-octylperoxyethyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyethyl monocarbonate, t-butylperoxy n-propyl monocarbonate, t-pentylperoxy n-propyl monocarbonate, t-hexylperoxy peroxy isopropyl monocarbonate, t-heptylperoxy isopropyl monocarbonate, t-octylperoxy isopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isopropyl monocarbonate, t-butylperoxy isopropyl monocarbonate, t-pentylperoxy isopropyl monocarbonate, t-hexylperoxy isopropyl monocarbonate, t-heptylperoxy isopropyl monocarbonate, t-octylperoxy isopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isopropyl monocarbonate, t-butylperoxy n-butyl monocarbonate, t-pentylperoxy n-butyl monocarbonate, t-hexylperoxy n-butyl monocarbonate, t-heptylperoxy n-butyl monocarbonate, t-octylperoxy n-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy n-butyl monocarbonate, t-butylperoxy isobutyl monocarbonate, t-pentylperoxy isobutyl monocarbonate, t -Hexylperoxy isobutyl monocarbonate, t-heptylperoxy isobutyl monocarbonate, t-octylperoxy isobutyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy isobutyl monocarbonate, t-butylperoxy sec-butyl monocarbonate, t-pentylperoxy sec-butyl monocarbonate, t-hexylperoxy sec-butyl monocarbonate, t-heptylperoxy sec-butyl monocarbonate, t-octylperoxy sec-butyl monocarbonate t-butylperoxy t-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy sec-butyl monocarbonate, t-butylperoxy t-butyl monocarbonate, t-pentylperoxy t-butyl monocarbonate, t-hexylperoxy t-butyl monocarbonate, t-heptylperoxy t-butyl monocarbonate, t-octylperoxy t-butyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy t-butyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-pentylperoxy 2-ethylhexyl monocarbonate ethylhexyl monocarbonate, t-hexylperoxy 2-ethylhexyl monocarbonate, t-heptylperoxy 2-ethylhexyl monocarbonate, t-octylperoxy 2-ethylhexyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexyl monocarbonate, diisobutyl peroxide, cumyl peroxy neodecanoate, 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-tetramethylbutylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy) Examples of organic peroxides include hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxy-2-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-butylperoxycyclohexyl)propane, and 2,2-di-t-butylperoxybutane. One organic peroxide may be used alone, or two or more organic peroxides may be used in combination.

[0032] Among these, t-butylperoxyisopropyl monocarbonate, t-pentylperoxyisopropyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy2-ethylhexyl monocarbonate, t-pentylperoxy2-ethylhexyl monocarbonate, t-hexylperoxy2-ethylhexyl monocarbonate, t-amylperoxyisopropyl monocarbonate, di-t-hexyl peroxide, t-butylperoxy2-ethylhexyl monocarbonate, Peroxymethylbutylperoxyisobutyrate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate are preferred organic peroxides because they can efficiently promote crosslinking of PHA.

[0033] The peroxide is preferably a compound having a one-hour half-life temperature of 200° C. or less, more preferably 170° C. or less, and even more preferably 140° C. or less, so that the heating temperature during the crosslinking treatment can be set low. The lower limit may be 50° C. or more, 60° C. or more, or 70° C. or more.

[0034] Particularly preferred organic peroxides exhibiting such a one-hour half-life temperature include t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate.

[0035] When the peroxide is an inorganic peroxide, examples of the inorganic peroxide include hydrogen peroxide, potassium peroxide, calcium peroxide, sodium peroxide, magnesium peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate, taking into consideration the heating temperature and time during the crosslinking treatment. Among these, hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate are preferred because they are easy to handle and have decomposition temperatures suitable for the heating temperature during the crosslinking treatment. One type of inorganic peroxide may be used alone, or two or more types may be used in combination. Furthermore, an organic peroxide and an inorganic peroxide may be used in combination.

[0036] <Polyfunctional Compound> The crosslinked structure in the crosslinked resin particles (B) may be introduced using only a peroxide, or may be introduced using both a peroxide and a polyfunctional compound, which makes it possible to increase the gel fraction of the crosslinked resin particles (B) with a smaller amount of peroxide.

[0037] The polyfunctional compound refers to a compound having two or more functional groups capable of crosslinking PHA in one molecule. Although not particularly limited, a compound having reactivity with radicals generated from peroxide is preferred, and a compound having two or more radical reactive groups in one molecule is particularly preferred. The radical reactive group is preferably at least one selected from the group consisting of a vinyl group, an allyl group, an acryloyl group, or a methacryloyl group.

[0038] Such polyfunctional compounds are not particularly limited, but examples thereof include allyl (meth)acrylate, allyl alkyl (meth)acrylates, allyloxyalkyl (meth)acrylates, polyfunctional (meth)acrylates having two or more (meth)acrylic groups such as ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol (meth)acrylate, divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. Preferred are allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene, and particularly preferred are allyl methacrylate and triallyl isocyanurate.

[0039] When a crosslinked structure is formed in the presence of a polyfunctional compound, the resulting crosslinked resin particles (B) may generally contain a structure derived from the polyfunctional compound, in which case molecular chains of the PHA are bonded to each other via the structure derived from the polyfunctional compound.

[0040] The crosslinked resin particles (B) may be composed solely of a PHA having a crosslinked structure, or may further contain components other than the PHA having a crosslinked structure, such as resins other than PHA, antioxidants, hydrolysis inhibitors, antiblocking agents, crystal nucleating agents, and ultraviolet absorbers.

[0041] The proportion of PHA in the crosslinked resin particles (B) is not particularly limited, but may be 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more. It may also be 99% by weight or more. The upper limit is not particularly limited, and it may be 100% by weight or less.

[0042] Examples of resins other than PHA include aliphatic polyesters having a structure in which an aliphatic diol and an aliphatic dicarboxylic acid are polycondensed, and aliphatic-aromatic polyesters having both an aliphatic compound and an aromatic compound as monomers. Examples of the former include polyethylene succinate, polybutylene succinate (PBS), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (PBSA), polyethylene sebacate, and polybutylene sebacate. Examples of the latter include poly(butylene adipate-co-butylene terephthalate) (PBAT), poly(butylene sebacate-co-butylene terephthalate), poly(butylene azelate-co-butylene terephthalate), poly(butylene succinate-co-butylene terephthalate) (PBST), etc. The other resins may be used singly or in combination of two or more.

[0043] The crosslinked resin particles (B) are different from the expanded resin particles disclosed in WO 2007 / 049694 and WO 2019 / 146555, and are preferably non-expanded, i.e., do not contain substantially any air bubbles inside the particles.

[0044] When not expanded, the crosslinked resin particles (B) have a relatively high apparent density of 0.6 g / cm ３ It is preferable that the density exceeds 0.7 g / cm ３ More preferably, it is 0.9 g / cm or more. ３ The apparent density of the crosslinked resin particles (B) can be determined by the method described in JIS K0061 (Method for measuring density and specific gravity of chemical products) or JIS Z8807 (Method for measuring density and specific gravity of solids).

[0045] The average weight per particle of the crosslinked resin particles (B) is not particularly limited, but since the crosslinked resin particles (B) have a small particle size with a volume average particle diameter of 10 μm or less, the value is far less than 0.1 mg.

[0046] The crosslinked resin particles (B) may be dried, and the shape of the dried particles may be powder, pellets, crumbs, sheets, or the like, depending on the drying method.

[0047] <Method for producing crosslinked resin particles (B)> An example of a method for producing crosslinked resin particles (B) will be specifically described. The crosslinked resin particles (B) can be produced by crosslinking PHA in the presence of a peroxide in an aqueous dispersion containing PHA particles before crosslinking treatment. In order to efficiently crosslink the PHA, it is preferable to heat the aqueous dispersion of PHA particles containing a peroxide to a temperature suitable for decomposing the peroxide.

[0048] More specifically, the method for producing the crosslinked resin particles (B) preferably includes the steps of: (1) preparing an aqueous dispersion of PHA particles in which pre-crosslinked PHA particles are dispersed in water; (2) adding a peroxide to the aqueous dispersion of PHA particles to impregnate the PHA particles with the peroxide; and (3) heating the aqueous dispersion of PHA particles impregnated with the peroxide to a heating temperature to crosslink the PHA. Furthermore, the method more preferably includes the step of (4) maintaining the heating temperature after all the peroxide has been added.

[0049] In step (1), the aqueous dispersion of PHA particles may be an aqueous dispersion obtained by culturing a PHA-producing microorganism to accumulate PHA in the cells, disrupting the cells in the culture solution, and separating and removing the cell components, or an aqueous dispersion obtained by concentrating or diluting the aqueous dispersion. According to such a method, the process from producing PHA particles by culturing a PHA-producing microorganism to crosslinking treatment can be carried out without separating the PHA particles from water.

[0050] Alternatively, an aqueous dispersion of PHA particles can be prepared by dispersing dried PHA particles in water. The aqueous dispersion may contain, in addition to water, an organic solvent that is compatible with water.

[0051] In the aqueous dispersion, the volume average particle diameter of the PHA particles is preferably within the same range as that of the crosslinked resin particles (B) described above. In the case of PHA particles produced by a PHA-producing microorganism, the volume average particle diameter can usually be within the above range, so that an aqueous dispersion of PHA particles having a desired volume average particle diameter can be obtained without carrying out a special step for adjusting the particle diameter.

[0052] The concentration of the PHA particles in the aqueous dispersion is not particularly limited and can be set appropriately, but may be, for example, about 1 to 70% by weight, preferably about 5 to 50% by weight.

[0053] The aqueous dispersion of PHA particles preferably contains a dispersant in order to improve the dispersibility of PHA particles and to make the crosslinking reaction proceed uniformly.As the dispersant, for example, anionic surfactants such as dioctyl sodium sulfosuccinate, sodium dodecyl sulfate, sodium lauryl sulfate, sodium oleate, etc.; cationic surfactants such as lauryl trimethyl ammonium chloride, etc.; nonionic surfactants such as glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polyoxypropylene glycol, etc.; water-soluble polymers such as polyvinyl alcohol, ethylene-modified polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polymethacrylic acid, sodium polymethacrylate, etc.These dispersants may be used alone or in combination of two or more.

[0054] When a dispersant is used, the amount thereof to be added is not particularly limited, but may be, for example, 0.1 to 10 parts by weight, and preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of PHA particles.

[0055] In step (2), a peroxide is added to the aqueous dispersion of PHA particles obtained in step (1) to impregnate the PHA particles with the peroxide. The peroxide may be any of those described above. The peroxide may be added in various forms, such as a solid or liquid. Alternatively, a liquid diluted with a diluent or the like may be added. The peroxide may be added all at once, continuously, or in portions.

[0056] When a peroxide and the polyfunctional compound are used in combination, it is preferable to add the polyfunctional compound to the aqueous dispersion of PHA particles in step (2). The polyfunctional compound can be any of those described above. The polyfunctional compound can be added in various forms, such as solid or liquid. A liquid diluted with a diluent or the like may also be added. The polyfunctional compound may be added all at once, continuously, or in portions.

[0057] To impregnate the PHA particles with the peroxide and any polyfunctional compound, after or while adding these compounds to an aqueous dispersion of PHA particles, the temperature of the aqueous dispersion is set to, for example, 0°C or higher but lower than a temperature suitable for decomposing the peroxide employed in the next step (3), and the temperature is maintained for, for example, about 1 minute to 5 hours while stirring the aqueous dispersion. Specifically, the temperature of the aqueous dispersion during impregnation may be about 10 to 60°C.

[0058] The amount of peroxide used can be appropriately set in consideration of the gel fraction of the crosslinked resin particles (B), and is, for example, preferably 0.01 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, even more preferably 0.3 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, relative to 100 parts by weight of the PHA particles.

[0059] According to the manufacturing method of crosslinking PHA particles in aqueous dispersion using peroxide, crosslinking can be easily carried out while maintaining the particle size (volume) before crosslinking, and crosslinked resin particles can be easily obtained.On the other hand, it may be difficult to achieve this in the method of crosslinking resin by melt kneading in the presence of peroxide.In addition, according to the manufacturing method of crosslinking PHA particles in aqueous dispersion using peroxide, it is easy to control the temperature rise caused by the heat generated during the crosslinking reaction, and it is advantageous in efficiently obtaining crosslinked resin particles with a safe and stable crosslinked structure (quality).

[0060] The amount of the polyfunctional compound used may also be appropriately determined in consideration of the gel fraction of the crosslinked resin particles (B). For example, the amount is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 15 parts by weight, even more preferably 0.1 to 10 parts by weight, even more preferably 0.2 to 5 parts by weight, and particularly preferably 0.3 to 3 parts by weight, relative to 100 parts by weight of the PHA particles.

[0061] In step (3), the aqueous dispersion of PHA particles impregnated with peroxide is heated to a temperature suitable for decomposing the peroxide. The heating temperature is preferably within a range of about 25°C above or below the one-hour half-life temperature of the peroxide. Specifically, the heating temperature is preferably 30 to 140°C, more preferably 50 to 135°C, and even more preferably 60 to 130°C. This method makes it possible to crosslink the PHA at a temperature lower than the melting temperature of the PHA, thereby avoiding deterioration of the PHA due to heating during the crosslinking treatment.

[0062] In the subsequent step (4), it is preferable to maintain the heating temperature. This allows the crosslinking reaction using the peroxide to proceed sufficiently. The time for maintaining the heating temperature is not particularly limited, but is preferably 1 minute to 15 hours, and more preferably 1 hour to 10 hours.

[0063] After the crosslinking reaction is complete, the crosslinked resin particles (B) are separated from the aqueous dispersion and the water is removed to obtain dried crosslinked resin particles (B). The method for separating the crosslinked resin particles (B) is not particularly limited, and examples thereof include filtration, centrifugation, heat drying, freeze drying, and spray drying. For example, spray drying can be used to obtain dried crosslinked resin particles (B) directly from the aqueous dispersion. Furthermore, by extruding the crosslinked resin particles (B) alone after separation from the aqueous dispersion, the remaining water can be completely removed, and the crosslinked resin particles (B) can be obtained in pellet form. Furthermore, an aggregation process using a coagulant or pH adjustment may be performed.

[0064] In the thermoplastic resin composition according to this embodiment, the amount of crosslinked resin particles (B) is 10 to 60 parts by weight per 100 parts by weight of the total of the thermoplastic resin (A) and the crosslinked resin particles (B). Using the crosslinked resin particles (B) in this range can improve the mechanical strength, such as the impact strength, of the thermoplastic resin (A). The amount may be 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more. The upper limit of the amount is preferably 55 parts by weight or less, more preferably 50 parts by weight or less, and particularly preferably 45 parts by weight or less.

[0065] <Thermoplastic Resin (A)> In the thermoplastic resin composition according to this embodiment, the thermoplastic resin (A) serving as the matrix resin is not particularly limited as long as it is a resin that can be molded into a desired shape by being melted by heating and then cooled and solidified. Specific examples include polyolefin resins such as polyethylene and polypropylene, acrylic resins such as polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, and polymethyl methacrylic acid, AS resin, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyester resin, and cyclic polyolefin. These thermoplastic resins may be used alone or in combination of two or more.

[0066] As the thermoplastic resin (A), polyester-based resins are particularly preferred. Examples of such polyester-based resins include PHAs such as polyglycolic acid, poly(3-hydroxyalkanoate)-based resins, and poly(4-hydroxyalkanoate)-based resins; polylactic acid; aliphatic polyesters such as polyesters having a structure obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid; and aliphatic-aromatic polyesters having both an aliphatic compound and an aromatic compound as monomers. Examples of aliphatic polyesters other than PHAs include polycaprolactone, polyethylene succinate, polybutylene succinate (PBS), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (PBSA), polyethylene sebacate, and polybutylene sebacate. Examples of aliphatic aromatic polyesters include poly(butylene adipate-co-butylene terephthalate) (PBAT), poly(butylene sebacate-co-butylene terephthalate), poly(butylene azelate-co-butylene terephthalate), poly(butylene succinate-co-butylene terephthalate) (PBST), polyethylene furanoate, etc. These polyester resins may be used alone or in combination of two or more.

[0067] Since the crosslinked resin particles (B) are composed of a biodegradable PHA, it is preferable that the thermoplastic resin (A) also contains a biodegradable resin, which can enhance the biodegradability of the thermoplastic resin composition as a whole.

[0068] Furthermore, when the crosslinked resin particles (B) are produced from plant-derived raw materials, it is preferable that the thermoplastic resin (A) is also a resin produced from plant-derived raw materials from the viewpoint of resource circulation.

[0069] When the thermoplastic resin (A) contains a biodegradable resin, the content thereof is preferably 10 to 100% by weight, more preferably 30% by weight or more, even more preferably 50% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more, of the entire thermoplastic resin (A).

[0070] The biodegradable resin used as the thermoplastic resin (A) preferably contains the aliphatic polyester described above, and particularly preferably contains PHA and / or polylactic acid, because the crosslinked resin particles (B) have an excellent impact resistance improving effect. The PHA used as the thermoplastic resin (A) preferably does not have a crosslinked structure.

[0071] When the thermoplastic resin (A) contains PHA and / or polylactic acid, the content thereof is preferably 10 to 100% by weight, more preferably 30% by weight or more, even more preferably 50% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight or more, of the entire thermoplastic resin (A).

[0072] The PHA that can be used as the thermoplastic resin (A) is not particularly limited, and examples thereof include polyglycolic acid, P3HA, poly(4-hydroxyalkanoate)-based resins, etc. As the PHA, one type may be used alone, or two or more types may be used in combination. Of these, P3HA is particularly preferred.

[0073] The P3HA that can be used as the thermoplastic resin (A) is the same as the P3HA related to the crosslinked resin particles (B), and the various P3HAs described above can be used. The P3HA used as the thermoplastic resin (A) is preferably different from the P3HA used for the crosslinked resin particles (B), and is more preferably a resin that is harder than the P3HA used for the crosslinked resin particles (B).

[0074] When the P3HA used as the thermoplastic resin (A) contains 3-hydroxybutanoic acid (3HB) repeating units, from the viewpoint of the balance between flexibility and strength, the composition ratio of 3HB repeating units is preferably 80 to 99 mol%, more preferably 82 to 97 mol%, of all monomer repeating units (100 mol%). When the composition ratio of 3HB repeating units is 80 mol% or more, the rigidity of the P3HA can be further improved. On the other hand, when the composition ratio of 3HB repeating units is 99 mol% or less, the flexibility of the P3HA tends to be further improved. As P3HA, two or more types having different composition ratios of 3HB repeating units may be used in combination.

[0075] The molecular weight of the PHA used as the thermoplastic resin (A) is not particularly limited, but the weight-average molecular weight is preferably 50,000 to 3,000,000, more preferably 100,000 to 2,000,000, and more preferably 150,000 to 1,500,000. By setting the weight-average molecular weight to 50,000 or more, sufficient rigidity and strength can be obtained in the thermoplastic resin composition according to this embodiment. On the other hand, PHAs with a weight-average molecular weight exceeding 3,000,000 may be difficult to prepare or handle to achieve the objectives of the present invention.

[0076] The polylactic acid usable as the thermoplastic resin (A) may be any conventionally known polylactic acid, and may be either crystalline or amorphous. The polylactic acid may be a homopolymer of lactic acid or a copolymer of lactic acid and another monomer. Alternatively, it may be a blend of these. Examples of the other monomer include aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic polyhydric alcohols, aliphatic polycarboxylic acids, and polyfunctional polysaccharides.

[0077] The lactic acid raw material for producing polylactic acid is not particularly limited, and examples thereof include L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof, and L-lactide, D-lactide, meso-lactide, or a mixture thereof. Lactic acid obtained by microbial fermentation from renewable plant-derived raw materials such as starch is preferably used. The method for producing polylactic acid is not particularly limited, and known methods such as dehydration condensation polymerization and ring-opening polymerization can be used.

[0078] The molecular weight of the polylactic acid (A) used as the thermoplastic resin (A) is not particularly limited, but the weight-average molecular weight is preferably 50,000 to 1,000,000, more preferably 70,000 to 700,000, and more preferably 100,000 to 400,000. By setting the weight-average molecular weight to 50,000 or more, sufficient rigidity and strength can be obtained in the thermoplastic resin composition according to this embodiment. On the other hand, polylactic acid with a weight-average molecular weight exceeding 1,000,000 may be difficult to produce or handle to achieve the objectives of the present invention.

[0079] <Crystal Nucleating Agent> The thermoplastic resin composition may further contain a crystal nucleating agent. When the thermoplastic resin (A) is a crystalline resin, the inclusion of a crystal nucleating agent in the thermoplastic resin composition promotes crystallization during molding, thereby improving molding processability, productivity, etc. Furthermore, a thermoplastic resin composition having excellent heat resistance or mechanical properties can be obtained.

[0080] The crystal nucleating agent is not particularly limited, and conventionally known ones can be used, for example, inorganic substances such as talc, kaolinite, montmorillonite, mica, synthetic mica, clay, zeolite, silica, carbon black, graphite, boron nitride, zinc oxide, titanium oxide, tin oxide, calcium carbonate, magnesium carbonate, aluminum oxide, neodymium oxide, barium sulfate, sodium chloride, and metal phosphates; sugar alcohol compounds derived from natural products such as erythritol, pentaerythritol, galactitol, mannitol, and arabitol; polysaccharides such as chitin and chitosan; polyols such as aliphatic alcohols (polyols), polyvinyl alcohol, and polyethylene oxide;Sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, calcium oxalate, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, sodium cyclohexanecarboxylate and other organic carboxylic acid metal salts, organic sulfonates, such as sodium p-toluenesulfonate and sodium sulfoisophthalate, ethylenestearamide, ethylenebislauricamide, palmitic amide, hydroxybenzoates ... Carboxylic acid amides such as hydroxystearic acid amide, erucic acid amide, trimesic acid tris(t-butylamide), lauric acid esters, palmitic acid esters, oleic acid esters, stearic acid esters, erucic acid esters, N-oleyl palmitic acid esters, N-oleyl oleic acid esters, N-oleyl stearate esters, N-stearyl oleic acid esters, N-stearyl stearate esters, N-stearyl erucic acid esters, methylene bisstearate esters, ethylene bislaurate esters, ethylene bis(hydroxystearic acid amide), Carboxylic acid esters such as scapric acid ester, ethylene bisoleic acid ester, ethylene bisstearate ester, ethylene biserucic acid ester, ethylene bisisostearate ester, butylene bisstearate ester, and p-xylylene bisstearate ester; dicarboxylic acid derivatives such as dimethyl adipate, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate; cyclic compounds having a functional group C═O and a functional group selected from NH, S, and O in the molecule, such as indigo, quinacridone, and quinacridone magenta;Examples of suitable crystal nucleating agents include sorbitol derivatives such as bisbenzylidene sorbitol and bis(p-methylbenzylidene)sorbitol; compounds containing a nitrogen-containing heteroaromatic nucleus such as pyridine, triazine, and imidazole; phosphate ester compounds, bisamides of higher fatty acids, and metal salts of higher fatty acids; branched polylactic acid; and low-molecular-weight poly(3-hydroxybutyrate). These crystal nucleating agents may be used alone or in combination of two or more.

[0081] The content of the crystal nucleating agent is not particularly limited as long as it can promote the crystallization of the thermoplastic resin (A), but is preferably 0.05 to 12 parts by weight, more preferably 0.1 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight, relative to 100 parts by weight of the thermoplastic resin (A). When the content of the crystal nucleating agent is within the above range, the effect as a crystal nucleating agent can be obtained while suppressing a decrease in viscosity during molding and a decrease in the physical properties of the molded product.

[0082] <Lubricant> The thermoplastic resin composition may further contain a lubricant. The inclusion of a lubricant can improve the surface smoothness of the resulting molded article. Examples of the lubricant include, but are not limited to, fatty acid metal salts such as magnesium stearate and calcium stearate; fatty acid amides such as behenic acid amide, stearic acid amide, erucic acid amide, oleic acid amide, methylene bisstearic acid amide, and ethylene bisstearic acid amide; polyethylene wax, oxidized polyester wax; glycerin monofatty acid esters such as glycerin monostearate, glycerin monobehenate, and glycerin monolaurate; organic acid monoglycerides such as succinic acid saturated fatty acid monoglycerides; sorbitan fatty acid esters such as sorbitan behenate, sorbitan stearate, and sorbitan laurate; polyglycerin fatty acid esters such as diglycerin stearate, diglycerin laurate, tetraglycerin stearate, tetraglycerin laurate, decaglycerin stearate, and decaglycerin laurate; and higher alcohol fatty acid esters such as stearyl stearate. The lubricants may be used alone or in combination of two or more.

[0083] The content of the lubricant (when multiple lubricants are used, the total content) is not particularly limited as long as it can impart lubricity to the molded article, but is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, even more preferably 0.1 to 10 parts by weight, even more preferably 0.2 to 5 parts by weight, and particularly preferably 0.3 to 4 parts by weight, relative to 100 parts by weight of the thermoplastic resin (A). When the content of the lubricant is within the above range, it is possible to obtain the effect as a lubricant while avoiding bleeding out of the lubricant onto the surface of the molded article.

[0084] <Other Components> The thermoplastic resin composition according to this embodiment may contain other components such as a plasticizer; an organic filler; an inorganic filler; an antioxidant; a hydrolysis inhibitor; an ultraviolet absorber; a colorant such as a dye or a pigment; or an antistatic agent, to the extent that the functionality of the resulting molded article is not impaired.

[0085] The plasticizer is not particularly limited, and examples thereof include polyester-based plasticizers such as polypropylene glycol sebacate ester; aliphatic dibasic acid ester-based plasticizers such as di-1-butyl adipate, di-n-butyl sebacate, and di-2-ethylhexyl azelate; glycerin-based plasticizers such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate; polycarboxylic acid ester-based plasticizers such as tri-2-ethylhexyl acetylcitrate and tributyl acetylcitrate; polyethylene glycol, polypropylene glycol, poly(ethylene oxide-propylene oxide) block and / or random copolymer, and polytetramethylene glycol. and polyalkylene glycol-based plasticizers such as diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate; epoxy-based plasticizers such as epoxidized soybean oil and epoxidized linseed oil fatty acid butyl ester; and castor oil-based plasticizers such as castor oil fatty acid esters, methyl ricinoleate, ethyl ricinoleate, isopropyl ricinoleate, butyl ricinoleate, ethylene glycol monoricylate, propylene glycol monoricylate, trimethylolpropane monoricylate, sorbitan monoricylate, castor oil fatty acid polyethylene glycol esters, castor oil ethylene oxide adducts, castor oil-based polyols, castor oil-based toluene, and castor oil-based diols. These may be used alone or in combination of two or more.

[0086] The organic filler is not particularly limited, and examples thereof include fillers composed of wood-based materials such as wood chips, wood flour, and sawdust, and naturally-derived materials such as rice husks, rice flour, starch, corn starch, rice straw, wheat straw, and natural rubber; organic fibers such as natural plant fibers, natural animal fibers, and synthetic fibers; and fillers composed of synthetic resin materials such as polyester, polyacrylic, polyamide, nylon, polyethylene, polyolefin, polyvinyl alcohol, polyvinyl chloride, polyurethane, polyacetal, aramid, PBO (poly-p-phenylene benzobisoxazole), polyphenylene sulfide, acetyl cellulose, polybenzazole, polyarylate, polyvinyl acetate, and synthetic rubber.

[0087] Examples of the natural plant fibers include kenaf fiber, abaca fiber, bamboo fiber, jute fiber, hemp fiber, linen fiber, henequen (sisal), ramie fiber, hemp, cotton, banana fiber, coconut fiber, palm, paper mulberry, Mitsumata, bagasse, etc. Other examples include pulp and cellulose fiber processed from plant fibers, and regenerated fibers such as rayon. Examples of natural animal fibers include wool, silk, cashmere, mohair, etc.

[0088] The inorganic filler is not particularly limited, but examples thereof include silica-based inorganic fillers such as quartz, fumed silica, silicic anhydride, fused silica, crystalline silica, amorphous silica, fillers formed by condensing alkoxysilanes, and ultrafine amorphous silica, as well as alumina, zircon, iron oxide, zinc oxide, titanium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, glass, silicone rubber, silicone resin, titanium oxide, carbon fiber, mica, graphite, carbon black, ferrite, graphite, diatomaceous earth, clay, clay, talc, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, and silver powder. These may be surface-treated to improve dispersibility in the resin composition. These may be used alone or in combination of two or more.

[0089] The antioxidant is not particularly limited, but examples thereof include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, etc. These may be used alone or in combination of two or more.

[0090] The hydrolysis inhibitor is not particularly limited, but examples thereof include carbodiimide compounds, epoxy compounds, isocyanate compounds, oxazoline compounds, etc. These may be used alone or in combination of two or more.

[0091] The ultraviolet absorber is not particularly limited, and examples thereof include benzophenone-based compounds, benzotriazole-based compounds, triazine-based compounds, salicylic acid-based compounds, cyanoacrylate-based compounds, nickel complex salt-based compounds, etc. These may be used alone or in combination of two or more.

[0092] The colorants such as pigments and dyes are not particularly limited, and examples thereof include inorganic colorants such as titanium oxide, calcium carbonate, chromium oxide, cuprous oxide, calcium silicate, iron oxide, carbon black, graphite, titanium yellow, and cobalt blue, soluble azo pigments such as lake red, lithol red, and brilliant carmine, insoluble azo pigments such as dinitrian orange and fast yellow, phthalocyanine pigments such as monochlorophthalocyanine blue, polychlorophthalocyanine blue, and polybromophthalocyanine green, condensed polycyclic pigments such as indigo blue, perylene red, isoindolinone yellow, and quinacridone red, and dyes such as oracet yellow. These may be used alone or in combination of two or more.

[0093] The antistatic agent is not particularly limited, but examples thereof include low molecular weight antistatic agents such as fatty acid ester compounds, aliphatic ethanolamine compounds, and aliphatic ethanolamide compounds, and polymeric antistatic agents, etc. These may be used alone or in combination of two or more.

[0094] The thermoplastic resin composition according to the present embodiment may further contain any of the following additives: catalyst deactivators (hindered phenol compounds, thioether compounds, vitamin compounds, triazole compounds, polyamine compounds, hydrazine derivative compounds, phosphorus compounds, etc.), mold release agents (montanic acid and its salts, esters thereof, half esters thereof, stearyl alcohol, stearamide, polyethylene wax, etc.), color inhibitors (phosphites, hypophosphites, etc.), silane coupling agents (epoxy silane coupling agents, amino silane coupling agents, (meth)acrylic silane coupling agents, isocyanate silane coupling agents, etc.), flame retardants (red phosphorus, phosphate esters, brominated polystyrene, brominated polyphenylene ether, etc.), , brominated polycarbonate, aluminum hydroxide, magnesium hydroxide, melamine and cyanuric acid or salts thereof, silicon compounds, etc.), conductive agents (carbon black, etc.), sliding property improvers (graphite, fluororesin, etc.), epoxy compounds (glycidyl ether compounds, glycidyl ester compounds, polymer compounds grafted or copolymerized with a glycidyl compound, etc.), acid anhydride compounds (maleic anhydride, succinic anhydride, polymer compounds grafted or copolymerized with an acid anhydride, etc.), carbodiimide compounds (N,N'-di-2,6-diisopropylphenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, polycarbodiimide, etc.), etc.

[0095] The content of each of the other components described above is not particularly limited as long as the effects of the invention are achieved, and can be appropriately determined by a person skilled in the art.

[0096] [Method for producing thermoplastic resin composition] The thermoplastic resin composition according to this embodiment can be produced by a known method. Specifically, a method of melt-kneading the thermoplastic resin (A), crosslinked resin particles (B), and optional components such as a crystal nucleating agent, a lubricant, and other components using an extruder, kneader, Banbury mixer, kneading roll, or the like can be mentioned. When melt-kneading, it is preferable to mix them while taking care to avoid a decrease in molecular weight due to thermal decomposition. Alternatively, the thermoplastic resin composition can be produced by dissolving each component in a soluble solvent and then removing the solvent.

[0097] When producing by melt kneading, each component may be charged separately into an extruder, etc., or each component may be mixed in advance and then charged into an extruder, etc. For example, an aqueous dispersion of the thermoplastic resin (A) and an aqueous dispersion of the crosslinked resin particles (B) may be mixed and then dried to obtain a mixed powder, which may then be charged into an extruder, etc.

[0098] When melt-kneaded using an extruder, the obtained thermoplastic resin composition may be extruded into a strand shape and then cut to be processed into particle shapes such as a bar shape, a cylindrical shape, an elliptical cylindrical shape, a sphere shape, a cube shape, a rectangular parallelepiped shape, or the like.

[0099] The resin temperature during melt-kneading cannot be generally specified because it depends on the melting point, melt viscosity, etc. of the resin used. However, from the viewpoint of uniformly dispersing the crosslinked resin particles (B) while avoiding thermal decomposition of the thermoplastic resin (A), the temperature is preferably 140 to 220°C, more preferably 150 to 210°C, and even more preferably 160 to 200°C.

[0100] <Method for producing molded article> A molded article can be produced from the thermoplastic resin composition according to this embodiment. The molding method is not particularly limited, and a commonly used molding method can be applied, but specific examples include inflation film molding, extrusion blow molding, injection blow molding, extrusion molding, calendar molding, vacuum forming, and injection molding.

[0101] According to this embodiment, these molding methods can produce molded articles with improved impact resistance, specifically, sheets, films, blow molded articles, extrusion molded articles, vacuum molded articles, and injection molded articles, with good productivity.

[0102] Molded articles made from the thermoplastic resin composition according to this embodiment can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and other fields.

[0103] The following items are preferred embodiments of the present disclosure, but the present invention is not limited to them. [Item 1] A thermoplastic resin composition comprising 40 to 90 parts by weight of a thermoplastic resin (A) and 10 to 60 parts by weight of crosslinked resin particles (B) containing a polyhydroxyalkanoate resin and having a gel fraction of 50% or more (where the total amount of (A) and (B) is 100 parts by weight). [Item 2] The thermoplastic resin composition according to item 1, wherein the polyhydroxyalkanoate resin is a poly(3-hydroxyalkanoate) resin. [Item 3] The thermoplastic resin composition according to item 1 or 2, wherein the crosslinked resin particles (B) have a volume average particle diameter of 0.1 μm or more and 10 μm or less. [Item 4] The thermoplastic resin composition according to any one of items 1 to 3, wherein the crosslinked resin particles (B) are crosslinked using a peroxide. [Item 5] The thermoplastic resin composition according to any one of items 1 to 4, wherein the crosslinked resin particles (B) are further crosslinked in the presence of a polyfunctional compound. [Item 6] The thermoplastic resin composition according to any one of Items 1 to 5, wherein the crosslinked resin particles (B) are not foamed. [Item 7] The thermoplastic resin composition according to any one of Items 1 to 6, wherein the proportion of the polyhydroxyalkanoate resin in the crosslinked resin particles (B) is 80% by weight or more. [Item 8] The thermoplastic resin composition according to any one of Items 1 to 7, wherein the thermoplastic resin (A) comprises a biodegradable resin. [Item 9] The thermoplastic resin composition according to Item 8, wherein the biodegradable resin is a polyester resin. [Item 10] The thermoplastic resin composition according to any one of Items 1 to 9, further comprising a crystal nucleating agent and / or a lubricant. [Item 11] A molded article of the thermoplastic resin composition according to any one of Items 1 to 10. [Item 12] The molded article according to Item 11, which is a sheet, film, blow-molded article, extrusion-molded article, vacuum-molded article, or injection-molded article. [Item 13] A modifier for thermoplastic resins, comprising crosslinked resin particles (B) containing a polyhydroxyalkanoate resin and having a gel fraction of 50% or more.

[0104] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0105] [1] Measurement conditions 1-1. Weight average molecular weight The resin to be measured was dissolved in chloroform and heated in a hot water bath at 60°C for 30 minutes. The soluble matter was filtered through a disposable PTFE filter with a 0.45 μm pore size. The filtrate was then subjected to GPC measurement under the following conditions to determine the weight average molecular weight. GPC measurement device: High performance liquid chromatograph 20A system manufactured by Shimadzu Corporation Column: K-G 4A (1 column), K-806M (2 columns) manufactured by Showa Denko K.K. Sample concentration: 1 mg / ml Free liquid: chloroform solution Free liquid flow rate: 1.0 ml / min Sample injection amount: 100 μL Analysis time: 30 minutes Standard sample: standard polystyrene

[0106] 1-2. Volume average particle diameter The volume average particle diameter of the crosslinked resin particles or uncrosslinked resin particles was measured in the state of resin particle latex. The measuring device used was a Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.

[0107] 1-3. Gel Fraction A dried product of crosslinked resin particles or uncrosslinked resin particles was added to chloroform to a concentration of 0.7% by weight, and dissolved at 60°C for 30 minutes to obtain a chloroform solution. After leaving the solution at room temperature for 3 hours, the chloroform solution was filtered through a membrane filter with a pore size of 0.45 μm. Losses were prevented by pouring chloroform over the inside of the container and the filter multiple times to thoroughly wash the solution before filtration. The gel remaining on the filter was dried, and the weight of the filter was measured, and the gel fraction was calculated using the following formula: Formula: Gel fraction = (weight of filter including dried gel - weight of filter only) / weight of crosslinked resin particles or uncrosslinked resin particles used in measurement x 100 (%)

[0108] [2] Raw materials for crosslinked resin particles 2-1. Uncrosslinked resin particles PHA-1: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): (3-hydroxybutyrate) / (3-hydroxyhexanoate) = 72 / 28 (mol / mol), weight average molecular weight Mw: 700,000 to 1,500,000 PHA-2: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): (3-hydroxybutyrate) / (3-hydroxyhexanoate) = 68 / 32 (mol / mol), weight average molecular weight Mw: 700,000 to 1,500,000 PHA-3: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): (3-hydroxybutyrate) / (3-hydroxyhexanoate) = 75 / 25 (mol / mol), weight average molecular weight Mw: 600,000 to 1,500,000 2-2. 2-3. Peroxides PO-1: t-butyl peroxypivalate ("Luperox 11" manufactured by Arkema Yoshitomi Co., Ltd., 1-hour half-life temperature: 76°C) PO-2: t-butylperoxy-2-ethylhexanoate ("Luperox 26" manufactured by Arkema Yoshitomi Co., Ltd., 1-hour half-life temperature: 95°C) PO-3: t-butylperoxy-2-ethylhexyl monocarbonate ("Perbutyl E" manufactured by NOF Corporation, 1-hour half-life temperature: 119°C) PO-4: di-sec-butyl peroxydicarbonate ("Luperox 225" manufactured by Arkema Yoshitomi Co., Ltd., 1-hour half-life temperature: 69°C) 2-3. Polyfunctional compounds CA-1: allyl methacrylate CA-2: triallyl isocyanurate

[0109] [3] Method for Producing Crosslinked Resin Particles The crosslinked resin particles of Production Examples 1 to 19 were produced using the types of raw materials listed in Table 1 in the amounts listed in Table 1 and according to the procedure described below. An aqueous dispersion (100 parts by weight of solids) of uncrosslinked resin particles dispersed in water, 200 parts by weight of deionized water, a predetermined amount of peroxide, 2 parts by weight of sodium dioctyl sulfosuccinate, and a predetermined amount of polyfunctional compound were added to an autoclave equipped with a stirrer, baffles, a nitrogen inlet / outlet, and a thermometer. Stirring was initiated at room temperature, and the autoclave was simultaneously purged with nitrogen. The contents of the autoclave were then stirred at the temperature and for the time specified in Table 1 to impregnate the uncrosslinked resin particles with the peroxide and polyfunctional compound. The temperature was then raised to the reaction temperature specified in Table 1. After reaching the reaction temperature, the mixture was reacted at the reaction temperature for the reaction time specified in Table 1 under the crosslinking conditions, yielding an aqueous dispersion of crosslinked resin particles dispersed in water. After adjusting the pH of the aqueous dispersion, the crosslinked resin particles were dried in an oven to obtain solidified crosslinked resin particles. The volume average particle size and gel fraction of the crosslinked resin particles obtained in each production example were measured by the above-mentioned methods, and the results are shown in Table 1.

[0110] The volume average particle size and gel fraction of the uncrosslinked resin particles before the crosslinking reaction were measured by the above-mentioned methods, and the results are shown as a reference example in Table 1. The uncrosslinked resin particles or their aqueous dispersions were used in Comparative Examples 2 to 4 and 8.

[0111]

[0112]

[0113] [4] Physical property evaluation 4-1. Components of test specimens (a) Thermoplastic resin (A): Amount (parts by weight) shown in Table 2 Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (Kaneka Biodegradable Polymer PHBH (registered trademark) manufactured by Kaneka Corporation), (3-hydroxybutyrate) / (3-hydroxyhexanoate)=94.4 / 5.6 (mol / mol), weight average molecular weight Mw: 530,000 (b) Crosslinked resin particles (B) or uncrosslinked resin particles prepared in Production Examples 1 to 19: Amount (parts by weight) shown in Table 2 (c) Pentaerythritol (Neuraizer P manufactured by Nippon Synthetic Chemical Industry Co., Ltd.): 1 part by weight (d) Behenic acid amide (BNT22H manufactured by Nippon Fine Chemical Co., Ltd.): 0.5 part by weight

[0114] 4-2. Method for preparing test pieces (Examples 1 to 21 and Comparative Examples 1 to 4) The mixtures of (a), (b), (c), and (d) were kneaded for 180 seconds at a screw rotation speed of 100 rpm in a small twin-screw kneader (Xplore MC5 manufactured by DSM) with the barrel temperature heated to the temperature shown in Table 2, to obtain a kneaded product. This kneaded product was dried in a dryer at 80°C for 4 hours to sufficiently reduce the moisture content, and then press-molded to a predetermined thickness at 165°C to prepare test pieces.

[0115] (Example 22) An aqueous dispersion of thermoplastic resin (A) particles and an aqueous dispersion of crosslinked resin particles (B) prepared in Production Example 11 were mixed to a weight ratio of 70 / 30% solids, the pH was adjusted to 3.8, and the mixture was dried in an oven to obtain a resin mixture. This resin mixture and a mixture of (c) and (d) were kneaded under the same conditions as above to prepare test pieces.

[0116] 4-3. Conditions for measuring tensile impact strength After aging the 500 μm thick sheet prepared by the method described above for 7 days under conditions of 23°C and 50% RH, test pieces according to JIS K 71603 were punched out and subjected to a tensile impact test according to JIS K 7160 Method A. The results are shown in Table 2.

[0117]

[0118]

[0119] Table 2 shows that Examples 1, 4, and 7 to 22, in which crosslinked resin particles (B) were blended with thermoplastic resin (A), had higher tensile impact strength values ​​and improved impact resistance compared to Comparative Example 1, in which only thermoplastic resin (A) was used. Furthermore, Examples 1, 4, 7 to 10, 12, and 15 to 21 had higher tensile impact strength values ​​and improved impact resistance compared to Comparative Example 3, in which the same blending amount of uncrosslinked resin particles was blended. The same can be said from the comparison between Comparative Example 2 and Example 11, and the comparison between Comparative Example 4 and Example 13.

[0120] [5] Evaluation of physical properties related to polylactic acid systems 5-1. Components of test specimens (a) Thermoplastic resin (A): Amount (parts by weight) shown in Table 3 Polylactic acid: 2003D manufactured by NatureWorks (b) Crosslinked resin particles (B), PBAT, or uncrosslinked resin particles prepared in Production Examples 1, 8, 11, 15, or 17: Amount (parts by weight) shown in Table 3 PBAT: Poly(butylene adipate-co-butylene terephthalate) (Ecoflex C1200 manufactured by BASF)

[0121] 5-2. Method for preparing test pieces (Examples 23 to 29 and Comparative Examples 5 to 8) The mixture of (a) and (b) was mixed for 180 seconds at a screw rotation speed of 100 rpm in a small twin-screw mixer (Xplore MC5 manufactured by DSM) with the barrel temperature heated to 175°C, to obtain a kneaded product. This kneaded product was dried in a dryer at 90°C for 2 hours to sufficiently reduce the moisture content, and then press-molded to a predetermined thickness at 170°C to prepare test pieces.

[0122] 5-3. Tensile impact strength measurement conditions The 500 μm thick sheets prepared by the method described above were aged for 7 days under conditions of 23°C and 50% RH, and then punched out into JIS K 71603 type test pieces, and subjected to a tensile impact test according to JIS K 7160 Method A. The results are shown in Table 3.

[0123]

[0124] Table 3 shows that in Examples 23 to 29, in which crosslinked resin particles (B) were blended with polylactic acid, which is the thermoplastic resin (A), the tensile impact strength values ​​were greater than in Comparative Example 5, which contained only polylactic acid, and that the impact resistance of polylactic acid was improved by blending crosslinked resin particles (B).

[0125] Furthermore, in Examples 23 to 29, the tensile impact strength values ​​were equal to or greater than those of Comparative Examples 6 to 8, in which PBAT or uncrosslinked resin particles were blended instead of the crosslinked resin particles (B), demonstrating the excellent effect of the crosslinked resin particles (B) in improving the impact resistance of polylactic acid. Comparing Comparative Example 7 with Example 25, the tensile impact strength when 10 parts by weight of crosslinked resin particles (B) were blended was significantly higher than that when 20 parts by weight of PBAT was blended, demonstrating the high impact resistance improving effect of the crosslinked resin particles (B).

[0126] [6] Evaluation of Bottle-Shaped Molded Articles 6-1. Method for Producing Bottle-Shaped Molded Articles (Examples 30 and 31 and Comparative Example 9) The raw materials used were (a), (b), (c), and (d) described in the section "4-1. Components of Test Pieces" above. However, as (b), the crosslinked resin particles (B) produced in Production Example 11 were used in the amount (parts by weight) described in Table 4. A mixture of these (a), (b), (c), and (d) was kneaded in a twin-screw kneader (KZW15TWIN-45WG, manufactured by Technovel Co., Ltd.) with the barrel temperature heated to 140 to 165°C and the screw rotation speed at 80 rpm to obtain a kneaded product. This kneaded product was dried in a dryer at 80°C for 4 hours to sufficiently reduce the moisture content. Thereafter, a bottle-shaped molded body having a volume of 328 ml, a thickness of 1.2 mm, an opening diameter of 66 mm, and a height of 1010 mm was produced using a 30MT injection molding machine (Si-30IV manufactured by Toyo Machinery & Metal Co., Ltd.) under conditions of a cylinder temperature of 140 to 165°C and a mold temperature of 40°C.

[0127] 6-2. Drop test of bottle-shaped molded body The bottle-shaped molded body prepared by the method described above and the water to be placed in the bottle-shaped molded body were placed in a thermostatic chamber adjusted to the test temperature shown in Table 4 for 12 hours or more for aging. Thereafter, the bottle-shaped molded body was filled with the amount of water shown in Table 4, the lid was placed on the bottle-shaped molded body, and the bottle-shaped molded body was allowed to free-fall vertically from the height shown in Table 4 up to 10 times in succession. The condition of the bottle-shaped molded body was checked immediately after each drop, and the test was terminated when cracks or breakage occurred. The results are shown in Table 4. If the bottle did not break after 10 consecutive drops, it was marked with "Good", and if it did break, the number of tries before it broke was recorded as a number.

[0128]

[0129] Table 4 shows that in Comparative Example 9, in which the thermoplastic resin (A) was not blended with crosslinked resin particles (B), the bottle-shaped molded body broke upon the first drop at 23°C with 100 g of water and a drop height of 100 cm. In contrast, in Examples 30 and 31, in which the crosslinked resin particles (B) were blended, the water weight was increased to 200 g and the bottle-shaped molded body remained unbroken even after 10 drops. Furthermore, under conditions of 2°C with 100 g of water and a drop height of 100 cm, Comparative Example 9, in which the crosslinked resin particles (B) were not blended, broke upon the second drop. In contrast, in Examples 30 and 31, in which the crosslinked resin particles (B) were blended, the bottle-shaped molded body remained unbroken even after 10 drops. Furthermore, in Example 31, the water weight was increased to 200 g and the bottle-shaped molded body remained unbroken even after 10 drops. From these results, it can be said that blending the crosslinked resin particles (B) with the thermoplastic resin (A) significantly improved the drop resistance of the bottle-shaped molded body.

Claims

1. Thermoplastic resin (A) 40 to 90 parts by weight, and A thermoplastic resin composition comprising: 10 to 60 parts by weight of crosslinked resin particles (B) containing a polyhydroxyalkanoate resin and having a gel fraction of 50% or more (wherein the total amount of (A) and (B) is 100 parts by weight).

2. 2. The thermoplastic resin composition according to claim 1, wherein the polyhydroxyalkanoate resin is a poly(3-hydroxyalkanoate) resin.

3. The thermoplastic resin composition according to claim 1 or 2, wherein the crosslinked resin particles (B) have a volume average particle size of 0.1 μm or more and 10 μm or less.

4. 3. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (B) are crosslinked using a peroxide.

5. The thermoplastic resin composition according to claim 4, wherein the crosslinked resin particles (B) are further crosslinked in the presence of a polyfunctional compound.

6. 3. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (B) are not foamed.

7. 3. The thermoplastic resin composition according to claim 1, wherein the crosslinked resin particles (B) contain the polyhydroxyalkanoate resin in an amount of 80% by weight or more.

8. The thermoplastic resin composition according to claim 1 or 2, wherein the thermoplastic resin (A) comprises a biodegradable resin.

9. The thermoplastic resin composition according to claim 8 , wherein the biodegradable resin is a polyester-based resin.

10. The thermoplastic resin composition according to claim 1 or 2, further comprising a crystal nucleating agent and / or a lubricant.

11. A molded article of the thermoplastic resin composition according to claim 1 or 2.

12. The molded article according to claim 11, which is a sheet, a film, a blow molded article, an extrusion molded article, a vacuum molded article, or an injection molded article.

13. A modifier for thermoplastic resins, comprising crosslinked resin particles (B) which contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more.

14. The poly(3-hydroxyalkanoate) resin contains 3-hydroxybutanoic acid repeat units, The thermoplastic resin composition according to claim 2, wherein the composition ratio of the 3-hydroxybutanoic acid repeating unit is 60 to 99 mol % in 100 mol % of all monomer repeating units of the poly(3-hydroxyalkanoate) resin.

15. A thermoplastic resin composition described in claim 1 or 2, wherein the crosslinked resin particles (B) are solidified.

16. A thermoplastic resin composition as described in Claim 7, wherein the proportion of the polyhydroxyalkanoate resin in the crosslinked resin particles (B) is 90 weight % or more.

17. The thermoplastic resin composition described in claim 1 or 2, wherein the gel fraction is 70% to 98%.

18. The modifier of claim 13, wherein the modifier is an impact modifier for thermoplastic resins.

19. A method for improving the impact resistance of a thermoplastic resin, comprising the steps of: The method includes a step of blending 40 to 90 parts by weight of a thermoplastic resin (A) with 10 to 60 parts by weight of crosslinked resin particles (B) (wherein the total amount of (A) and (B) is 100 parts by weight); The method for improving the impact resistance of a thermoplastic resin, wherein the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more.