Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
  • C08J3/122—Pulverisation by spraying
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2300/00—Characterised by the use of unspecified polymers
  • C08J2300/16—Biodegradable polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2300/00—Characterised by the use of unspecified polymers
  • C08J2300/22—Thermoplastic resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2371/00—Characterised by the use of polyethers obtained by reactions forming an ether link in the main chain; Derivatives of such polymers
  • C08J2371/02—Polyalkylene oxides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2400/00—Characterised by the use of unspecified polymers
  • C08J2400/16—Biodegradable polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2400/00—Characterised by the use of unspecified polymers
  • C08J2400/22—Thermoplastic resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2467/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2471/00—Characterised by the use of polyethers obtained by reactions forming an ether link in the main chain; Derivatives of such polymers
  • C08J2471/02—Polyalkylene oxides

Definitions

• the present invention relates to a resin powder containing crosslinked resin particles and a method for producing the same.
• Acrylic resins, acrylic silicone resins, polystyrene, etc. are known as resin materials that make up such crosslinked resin particles (see, for example, Patent Documents 1 and 2).
• 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 as a material that can solve this problem.
• Patent Document 3 describes how poly(3-hydroxyalkanoate), a type of biodegradable plastic, is crosslinked by melt-kneading the resin in the presence of an organic peroxide. However, it describes how the crosslinked resin produced by melt-kneading in this way is used to form films or sheets, and makes no mention at all of producing small crosslinked resin particles.
• crosslinked resin particles that are made of biodegradable plastics and exhibit biodegradability have not been known.
• the present inventors have succeeded in producing crosslinked resin particles made of a polyhydroxyalkanoate resin, which is a biodegradable resin, in an aqueous dispersion.
• the crosslinked resin particles are expected to be useful as environmentally friendly crosslinked resin particles that address the problem of plastic waste.
• the crosslinked resin particles adhere to each other as the water evaporates, forming a rubber-like sheet or a lump-like solid, making it difficult to separate the particles in a form that is easy to handle.
• the present invention aims to provide crosslinked resin particles composed of polyhydroxyalkanoate resin in a form that is easy to handle.
• the present invention relates to a resin powder having a median diameter of 20 to 1000 ⁇ m, the resin powder containing a thermoplastic resin (A) and crosslinked resin particles (B), the crosslinked resin particles (B) containing a polyhydroxyalkanoate-based resin, a gel fraction of 50% or more, and a volume average particle diameter of 0.1 ⁇ m or more and 10 ⁇ m or less.
• the present invention also relates to a method for producing the resin powder, comprising the steps of preparing an aqueous dispersion containing a thermoplastic resin (A) and crosslinked resin particles (B), and spray-drying the aqueous dispersion.
• crosslinked resin particles composed of polyhydroxyalkanoate resin can be provided in a form that is easy to handle.
• the resin powder according to the present embodiment contains at least a thermoplastic resin (A) and crosslinked resin particles (B).
• the resin powder has a particle size within a specific range, and therefore has good handleability.
• the crosslinked resin particles (B) will be described.
• the crosslinked resin particles (B) are particles composed of a polyhydroxyalkanoate resin as a main resin component.
• PHA polyhydroxyalkanoate resin
• 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.
• PHA is not particularly limited, but examples include polyglycolic acid, poly(3-hydroxyalkanoate)-based resins, poly(4-hydroxyalkanoate)-based resins, etc. 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. In the following, poly(3-hydroxyalkanoate)-based resins may be abbreviated as "P3HA.”
• the P3HA is a polyhydroxyalkanoate containing, as an essential repeating unit, a 3-hydroxyalkanoic acid repeating unit represented by the formula: [-CHR-CH 2 -CO-O-] (wherein R is an alkyl group represented by C n H 2n+1 , and n is an integer of 1 to 15).
• the P3HA preferably contains 50 mol % or more, and more preferably 70 mol % or more, of the 3-hydroxyalkanoic acid repeating units out of all monomer repeating units (100 mol %).
• P3HA is not particularly limited, and may be a homopolymer containing the repeating unit described above, or a copolymer containing the repeating unit described above.
• the copolymer include copolymers of 3-hydroxybutanoic acid (hereinafter sometimes referred to as "3HB") and one or more monomers selected from the group consisting of 3-hydroxypropionic acid, 3-hydroxypentanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 3-hydroxyundecanoic acid, 3-hydroxydodecanoic acid, 3-hydroxytridecanoic acid, 3-hydroxytetradecanoic acid, 3-hydroxyhexadecanoic acid, and 3-hydroxyoctadecanoic acid.
• 3HB 3-hydroxybutanoic acid
• copolymer examples include copolymers of 3HB and one or more monomers selected from the group consisting of 4-hydroxybutanoic acid, 4-hydroxypentanoic acid, 4-hydroxyhexanoic acid, 4-hydroxyheptanoic acid, 4-hydroxyoctanoic acid, 4-hydroxynonanoic acid, 4-hydroxydecanoic acid, 4-hydroxyundecanoic acid, 4-hydroxydodecanoic acid, 4-hydroxytridecanoic acid, 4-hydroxytetradecanoic acid, 4-hydroxyhexadecanoic acid, and 4-hydroxyoctadecanoic acid.
• monomers selected from the group consisting of 4-hydroxybutanoic acid, 4-hydroxypentanoic acid, 4-hydroxyhexanoic acid, 4-hydroxyheptanoic acid, 4-hydroxyoctanoic acid, 4-hydroxynonanoic acid, 4-hydroxydecanoic acid, 4-hydroxyundecanoic acid, 4-hydroxydodecanoic acid, 4-hydroxytridecanoic acid, 4-hydroxyt
• homopolymer or copolymer examples include, but are not limited to, poly(3-hydroxybutyrate) (abbreviation: P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviation: P3HB4HB), and the like.
• P3HA poly(3-hydroxybutyrate)
• P3HB3HH poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)
• P3HB4HB poly(3-hydroxybutyrate-co-4-hydroxybutyrate)
• P3HB4HB poly(3-hydroxybutyrate-co-4-hydroxybutyrate)
• poly(X-co-Y) refers to a copolymer containing X repeating units and Y repeating units, and is formed by copolymerizing a monomer from which the X repeating units are derived and a monomer from which the Y repeating units are derived.
• a small amount (less than 1 mol%) of a monomer may be copolymerized, but if this does not significantly affect the physical properties of the resulting P3HA, the monomer is considered not to be copolymerized, and the product will be called by a name that does not include that monomer.
• 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 P3HA, P3HB, P3HB3HH, and P3HB4HB are preferred, with P3HB3HH and P3HB4HB being more preferred, in terms of ease of industrial production.
• the composition ratio of the 3HB repeating units in all monomer repeating units is preferably 60 to 99 mol%, more preferably 61 to 97 mol%, and even more preferably 62 to 95 mol%, from the viewpoint of the balance between flexibility and strength.
• the composition ratio of the 3HB repeating units is 60 mol% or more, the crosslinked resin particles (B) or the resin particles before the crosslinking treatment are easily handled.
• the composition ratio of the 3HB repeating units is 99 mol% or less, the flexibility of the crosslinked resin particles (B) tends to be easily ensured.
• the monomer composition ratio of P3HA can be measured by gas chromatography or the like (see, for example, International Publication No. 2014/020838).
• P3HA two or more types having different composition ratios of the 3HB repeating units may be used in combination.
• the microorganisms that produce P3HA are not particularly limited as long as they have the ability to produce P3HA.
• the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other natural microorganisms are known, including Cupriavidus necator (formerly classified as Alcaligenes eutrophus, Ralstonia eutropha) and Alcaligenes latus. In these microorganisms, P3HB accumulates within the bacterial cells.
• 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.
• the weight average molecular weight 50,000 or more it is possible to avoid the tendency for the crosslinked resin particles (B) to have a low strength or to be sticky due to low molecular weight components.
• the weight average molecular weight 3,000,000 or less it is possible to make the PHA easier to produce and handle.
• the weight average molecular weight is a value measured before the PHA is crosslinked.
• the weight average molecular weight can be measured using gel permeation chromatography (GPC) (Shimadzu Corporation's "High Performance Liquid Chromatograph 20A System"), a polystyrene gel (Showa Denko KK's "K-G 4A", “K-806M”, etc.) as a column, chloroform as the mobile phase, and the molecular weight calculated as polystyrene.
• GPC gel permeation chromatography
• a polystyrene gel Showa Denko KK's "K-G 4A", “K-806M”, etc.
• chloroform as the mobile phase
• a calibration curve can be created using polystyrene with weight average molecular weights of 31,400, 197,000, 668,000, and 1,920,000.
• the column used in the GPC can be a column appropriate for measuring the molecular weight.
• 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 show a high gel fraction, specifically, a gel fraction of 50% or more. By showing such a high gel fraction, the hardness, heat resistance, solvent resistance, etc. of the resin particles containing PHA can be improved.
• the gel fraction 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 90% or more. There is no particular upper limit to the gel fraction, and it may be 100% or less, but from the viewpoint of production efficiency of the crosslinked resin particles (B), it is preferably 99.5% or less, and more preferably 99% or less. It may also be 98% or less, 97% or less, or 96% or less.
• the gel fraction is a value measured as follows. A dried product of the crosslinked resin particles (B) is added to chloroform so as to have a concentration of 0.7% by weight, and dissolved at 60° C. for 30 minutes to obtain a chloroform solution. After that, the solution is left to stand at room temperature for 3 hours, and then the chloroform solution is filtered through a membrane filter having a pore size of 0.45 ⁇ m. The gel remaining on the filter is dried, and the weight of the gel and the filter are measured, and the gel fraction is calculated according to the following formula.
• Formula: Gel fraction (weight of filter including dry gel ⁇ weight of filter only)/weight of crosslinked resin particles used in measurement ⁇ 100(%)
• the crosslinked resin particles (B) have a volume average particle diameter in the range of 0.1 ⁇ m to 10 ⁇ m.
• a resin powder having a particle diameter in a specific range according to the present embodiment can be formed, and can be used for various applications as described below.
• the lower limit of the particle diameter is preferably 0.1 ⁇ m or more, more preferably 0.3 ⁇ m or more, and even more preferably 0.5 ⁇ m or more.
• the upper limit of the particle diameter is preferably 8 ⁇ m or less, and more preferably 5 ⁇ m or less.
• 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 one example of such a device is the Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.
• 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.
• a peroxide When a peroxide is used, radicals generated by decomposition of the peroxide act on the PHA molecules to directly bond the molecular chains of the PHA to each other, thereby forming the crosslinked structure.
• the peroxide may be an organic peroxide or an inorganic peroxide.
• Organic peroxides are preferred because they can increase the gel fraction more efficiently.
• 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.
• 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 peroxy laurate, dimethyl di(benzoylperoxy)hexane, bis(butylperoxy)methylcyclohexane, bis(butylperoxy)cyclohexane, butyl peroxybenzoate, butyl bis(butylperoxy)valerate, dicumyl peroxide, di-t-hexyl peroxide, and t-butylperoxy 2-ethylhexanoate.
• t-butyl peroxyisobutyrate t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxymethyl monocarbonate, t-pentyl peroxymethyl monocarbonate, t-hexyl peroxymethyl monocarbonate, t-heptyl peroxymethyl monocarbonate, t-octyl peroxymethyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxymethyl monocarbonate, t-butyl peroxyethyl monocarbonate, t-pentyl peroxyethyl monocarbonate, t-hexyl peroxyethyl monocarbonate, t-heptyl peroxyethyl monocarbonate, t-octyl peroxyethyl monocarbonate, 1, 1,3,3-tetramethylbutylperoxyethyl monocarbonate, t-butylperoxy n-propyl monocarbonate,
• 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-ethyl Hexanoate, t-butylperoxyisobutyrate, t-hexylperoxy2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-hex
• 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.
• Particularly preferred organic peroxides exhibiting such a one-hour half-life temperature are t-butylperoxyisopropylmonocarbonate, t-butylperoxy2-ethylhexylmonocarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxy2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and 1,1,3,3-tetramethylbutylperoxyneodecanoate.
• 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.
• hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate are preferred in that they are easy to handle and have decomposition temperatures suitable for the heating temperature during the crosslinking treatment.
• the inorganic peroxide may be used alone or in combination of two or more types. Also, an organic peroxide and an inorganic peroxide may be used in combination.
• 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, since the latter method makes it possible to increase the gel fraction of the crosslinked resin particles (B) with a smaller amount of peroxide.
• the polyfunctional compound refers to a compound having two or more functional groups in one molecule that can crosslink PHA.
• a compound that is reactive with radicals generated from a 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.
• Such polyfunctional compounds are not particularly limited, but examples thereof include allyl (meth)acrylate; allyl alkyl (meth)acrylates; allyloxy alkyl (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. Allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene are preferred, and ally
• the resulting crosslinked resin particles (B) may usually contain a structure derived from the polyfunctional compound.
• the molecular chains of the PHA are bonded to each other via the structure derived from the polyfunctional compound.
• the crosslinked resin particles (B) may be composed only of PHA having a crosslinked structure, or may further contain components other than PHA having a crosslinked structure.
• components other than PHA having a crosslinked structure include resins other than PHA, antioxidants, hydrolysis inhibitors, antiblocking agents, crystal nucleating agents, ultraviolet absorbers, etc.
• 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. There is no particular upper limit, and it may be 100% by weight or less.
• resins other than PHA include polycaprolactone (PCL), polylactic acid (PLA), aliphatic polyesters consisting of a structure in which aliphatic diols and aliphatic dicarboxylic acids are polycondensed, and aliphatic aromatic polyesters having both aliphatic and aromatic compounds as monomers.
• the aliphatic polyesters include polyethylene succinate, polybutylene succinate (PBS), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (PBSA), polyethylene sebacate, and polybutylene sebacate.
• aliphatic aromatic polyester examples 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.
• PBAT poly(butylene adipate-co-butylene terephthalate)
• PBST poly(butylene sebacate-co-butylene terephthalate)
• PBST poly(butylene succinate-co-butylene terephthalate)
• 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 substantially contain air bubbles inside the particles.
• the crosslinked resin particles (B) When not expanded, the crosslinked resin particles (B) have a relatively large apparent density, preferably exceeding 0.6 g/cm 3 , more preferably 0.7 g/cm 3 or more, and even more preferably 0.9 g/cm 3 or more.
• 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).
• 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 ⁇ m or less, the value is far below 0.1 mg.
• the crosslinked resin particles (B) can be produced by crosslinking PHA in the presence of peroxide in an aqueous dispersion containing PHA particles before crosslinking treatment. In order to crosslink PHA efficiently, it is preferable to heat the aqueous dispersion of PHA particles containing peroxide to a temperature suitable for decomposing the peroxide.
• the method for producing the crosslinked resin particles (B) preferably includes the steps of: (1) preparing an aqueous dispersion of PHA particles in which the PHA particles before crosslinking treatment 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. It is even more preferable that the method further includes the step of (4) maintaining the heating temperature after all the peroxide has been added.
• the aqueous dispersion of PHA particles may be an aqueous dispersion obtained by culturing a PHA-producing microorganism to accumulate PHA in the cells, and then disrupting the cells in the culture medium to separate and remove the cell components, or an aqueous dispersion obtained by concentrating or diluting the aqueous dispersion.
• 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.
• 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, as described below.
• the volume average particle diameter of the PHA particles is preferably within the same range as the volume average particle diameter of the crosslinked resin particles (B) described above.
• 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 process for adjusting the particle diameter.
• the concentration of 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, and preferably about 5 to 50% by weight.
• the aqueous dispersion of PHA particles preferably contains a dispersant to increase the dispersibility of the PHA particles and to allow the crosslinking reaction to proceed uniformly.
• dispersants include anionic surfactants such as sodium dioctyl sulfosuccinate, sodium dodecyl sulfate, sodium lauryl sulfate, and sodium oleate; cationic surfactants such as lauryl trimethyl ammonium chloride; nonionic surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and polyoxyethylene polyoxypropylene glycol; and water-soluble polymers such as polyvinyl alcohol, ethylene-modified polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl
• the amount added is not particularly limited, but may be, for example, 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, per 100 parts by weight of PHA particles.
• 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 mentioned above.
• Peroxide may be added in various forms, such as solid or liquid. Alternatively, a liquid form diluted with a diluent may be added. The peroxide may be added all at once, or may be added continuously or in portions.
• the polyfunctional compound may be any of those mentioned above.
• the polyfunctional compound may 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, or may be added continuously or in portions.
• the temperature of the aqueous dispersion is set to, for example, 0°C or higher but lower than a temperature suitable for the decomposition of the peroxide employed in the next step (3), and while stirring the aqueous dispersion, the temperature is maintained, for example, for about 1 minute to 5 hours.
• the temperature of the aqueous dispersion during impregnation may be about 10 to 60°C.
• the amount of peroxide used can be set appropriately taking into consideration the gel fraction of the crosslinked resin particles (B), but for example, it is 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, per 100 parts by weight of PHA particles.
• the manufacturing method of crosslinking PHA particles in an aqueous dispersion using a peroxide it is easy to obtain crosslinked resin particles by proceeding with crosslinking while maintaining the particle size (volume) before crosslinking.
• the manufacturing method in which PHA particles are crosslinked in an aqueous dispersion using a peroxide makes it easy to control the temperature increase caused by the heat generated during the crosslinking reaction, which is advantageous for efficiently obtaining crosslinked resin particles having a safe and stable crosslinked structure (quality).
• the amount of the polyfunctional compound used may also be set appropriately taking into consideration the gel fraction of the crosslinked resin particles (B). For example, it 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, per 100 parts by weight of the PHA particles.
• 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 described above. Specifically, the heating temperature is preferably 30 to 140°C, more preferably 50 to 135°C, and even more preferably 60 to 130°C. According to this method, it is possible to crosslink the PHA at a temperature lower than the melting temperature of the PHA, so deterioration of the PHA due to heating during the crosslinking process can be avoided.
• the heating temperature is maintained. This allows the crosslinking reaction using peroxide to proceed sufficiently.
• the time for which the heating temperature is maintained is not particularly limited, but is preferably 1 minute to 15 hours, and more preferably 1 hour to 10 hours.
• an aqueous dispersion of crosslinked resin particles (B) can be obtained.
• This aqueous dispersion can be used to manufacture the resin powder according to this embodiment. Details will be described later.
• the resin powder according to the present embodiment contains a thermoplastic resin (A) in addition to the crosslinked resin particles (B).
• the thermoplastic resin (A) By containing the thermoplastic resin (A), the crosslinked resin particles (B) can be contained. In spite of this, it is possible to form a resin powder that has good handleability.
• the thermoplastic resin (A) is not particularly limited as long as it is a thermoplastic resin that can form a resin powder together with the crosslinked resin particles (B).
• 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 resins, and cyclic polyolefins. Only one type of these thermoplastic resins may be used, or two or more types may be used in combination.
• polyester resins are particularly preferred because of their good compatibility with the crosslinked resin particles (B) composed of polyhydroxyalkanoate resins.
• the polyester resins include PHAs such as polyglycolic acid, poly(3-hydroxyalkanoate) resins, and poly(4-hydroxyalkanoate) resins; polylactic acid; aliphatic polyesters such as polyesters having a structure in which aliphatic diols and aliphatic dicarboxylic acids are polycondensed; and aliphatic aromatic polyesters having both aliphatic and aromatic compounds as monomers.
• 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.
• PBS polybutylene succinate
• PBSA polyhexamethylene adipate
• PBSA polyhexamethylene adipate
• sebacate polybutylene sebacate
• polyesters examples 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.
• PBAT poly(butylene adipate-co-butylene terephthalate)
• PBST poly(butylene sebacate-co-butylene terephthalate)
• PBST poly(butylene succinate-co-butylene terephthalate)
• polyethylene furanoate etc.
• thermoplastic resin (A) also contains a biodegradable resin. In this case, the biodegradability of the resin powder as a whole can be increased.
• thermoplastic resin (A) is also a resin produced from raw materials derived from plants.
• the content is preferably 10 to 100% by weight of the entire thermoplastic resin (A), 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.
• 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, since it has good compatibility with the crosslinked resin particles (B) and is easy to produce a resin powder with good handleability.
• the PHA used as the thermoplastic resin (A) preferably does not have a crosslinked structure.
• the content is preferably 10 to 100% by weight of the entire thermoplastic resin (A), 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.
• thermoplastic resin (A) examples include polyglycolic acid, P3HA, poly(4-hydroxyalkanoate) resins, etc.
• PHA only one type may be used, or two or more types may be used in combination. Of these, P3HA is particularly preferred.
• 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 mentioned 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).
• the composition ratio of the 3HB repeat units in all monomer repeat units (100 mol%) is preferably 80 to 99 mol%, and more preferably 82 to 97 mol%.
• the composition ratio of the 3HB repeat units is 80 mol% or more, the rigidity of the P3HA can be further improved.
• the composition ratio of the 3HB repeat units is 99 mol% or less, the flexibility of the P3HA tends to be further improved.
• Two or more types of P3HA having different composition ratios of the 3HB repeat units may be used in combination.
• 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.
• the weight average molecular weight 50,000 or more the resin powder according to this embodiment can achieve good rigidity and strength.
• the weight average molecular weight 3,000,000 or less the production and handling of the PHA can be facilitated.
• any conventionally known polylactic acid can be used, and it may be either crystalline or amorphous.
• the polylactic acid may be a homopolymer of lactic acid, a copolymer of lactic acid and another monomer, or a blend thereof.
• the other monomers include aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic polyhydric alcohols, aliphatic polycarboxylic acids, and polyfunctional polysaccharides.
• the lactic acid raw material for producing polylactic acid is not particularly limited either, and L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof, or L-lactide, D-lactide, meso-lactide, or a mixture thereof, etc., can be used. Lactic acid obtained by microbial fermentation from renewable raw materials derived from plants such as starch can be suitably used.
• the method for producing polylactic acid is not particularly limited, and any known method such as dehydration condensation polymerization or ring-opening polymerization can be used.
• the molecular weight of the polylactic acid 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.
• the weight average molecular weight 50,000 or more the resin powder according to this embodiment can achieve good rigidity and strength.
• the weight average molecular weight 1,000,000 or less the production and handling of the polylactic acid can be facilitated.
• the resin powder according to this embodiment contains the thermoplastic resin (A) and the crosslinked resin particles (B).
• the content of the crosslinked resin particles (B) in the total of the thermoplastic resin (A) and the crosslinked resin particles (B) is preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 30% by weight or more, since the effect of the crosslinked resin particles (B) is easily realized. It may be 40% by weight or more.
• the upper limit of the content of the crosslinked resin particles (B) is preferably 90% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less, since the handleability of the resin powder can be further improved. It may be 60% by weight or less.
• the resin powder according to this embodiment may be substantially composed only of a thermoplastic resin (A) and crosslinked resin particles (B), but may also contain one or more of the following, as long as the effects of the invention are not impaired: a dispersant or emulsifier, a pH adjuster, an inorganic filler, a colorant such as a pigment or dye, an odor absorber such as activated carbon or zeolite, a fragrance such as vanillin or dextrin, a plasticizer, an antioxidant, an antioxidant, a weather resistance improver, an ultraviolet absorber, a crystal nucleating agent, a lubricant, a release agent, a water repellent, an antibacterial agent, a sliding property improver, and the like. Furthermore, the resin powder according to this embodiment may contain various components resulting from the process of the production method, as long as the effects of the invention are not impaired.
• the resin powder according to this embodiment is mainly composed of thermoplastic resin (A) and crosslinked resin particles (B).
• the total proportion of thermoplastic resin (A) and crosslinked resin particles (B) in the entire resin powder may usually be 60 to 100% by weight, 80 to 100% by weight, 90 to 100% by weight, 95 to 100% by weight, or 99 to 100% by weight.
• the upper limit may be 99.9% by weight or less, or 99% by weight or less.
• the resin powder according to the present embodiment may have a median diameter in the range of 20 ⁇ m or more and 1000 ⁇ m or less, from the viewpoint of improving the handleability of the resin powder.
• the lower limit may be 30 ⁇ m or more.
• the upper limit may be 500 ⁇ m or less, 300 ⁇ m or less, 200 ⁇ m or less, or 100 ⁇ m or less.
• the median diameter of the resin powder is a value measured by a dry or wet laser diffraction/scattering method using, for example, an LMS-3000 manufactured by Seishin Enterprise Co., Ltd. When measuring by a wet method, it is preferable to add the resin powder to an aqueous solution to which a small amount of a surfactant is added as a dispersant, and to measure the resin powder in a state where it is not aggregated.
• the resin powder according to this embodiment preferably has a low moisture content; specifically, the moisture content is preferably 5% by weight or less, more preferably 3% by weight or less, and even more preferably 1% by weight or less.
• the method for producing the resin powder according to the present embodiment is not particularly limited, but the resin powder can be suitably produced by preparing an aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) and spray-drying the aqueous dispersion.
• An aqueous dispersion containing a thermoplastic resin (A) and crosslinked resin particles (B) can be prepared by adding the thermoplastic resin (A) to an aqueous dispersion of the crosslinked resin particles (B).
• the aqueous dispersion of the crosslinked resin particles (B) can be produced as described above.
• thermoplastic resin (A) added to the aqueous dispersion of the crosslinked resin particles (B) may be in powder form or may be an aqueous dispersion of the thermoplastic resin (A).
• the volume average particle diameter of the thermoplastic resin (A) in the aqueous dispersion is preferably in the range of 0.1 ⁇ m or more and 10 ⁇ m or less.
• a thermoplastic resin (A) having such a particle diameter it is possible to suitably manufacture a resin powder having a particle diameter in the specific range according to this embodiment.
• the lower limit of the particle diameter is preferably 0.1 ⁇ m or more, more preferably 0.3 ⁇ m or more, and even more preferably 0.5 ⁇ m or more.
• the upper limit of the particle diameter is preferably 8 ⁇ m or less, and more preferably 5 ⁇ m or less.
• thermoplastic resin (A) when powdered thermoplastic resin (A) is added to an aqueous dispersion of crosslinked resin particles (B), it is preferable that the volume average particle size of the thermoplastic resin (A) after addition is in the range of 0.1 ⁇ m to 10 ⁇ m, as described above.
• the aqueous dispersion of the thermoplastic resin (A) may be an emulsion.
• the resin may be dissolved in a solvent by heating, crystallized, and then pulverized by high-speed stirring with glass beads (see, for example, paragraph [0008] of JP-A-9-78494), or may be produced by mixing and kneading a molten resin with an aqueous solution of a surfactant (see, for example, paragraph [0006] of JP-A-11-92712 and paragraph [0006] of JP-A-2001-354841), or may be produced by freeze-pulverizing the resin and then dispersing it in water.
• the aqueous dispersion of the thermoplastic resin (A) may be an aqueous dispersion obtained by culturing a PHA-producing microorganism to accumulate the PHA in the cells, and then destroying the cells in the culture medium to separate and remove the cell components, or an aqueous dispersion obtained by concentrating or diluting the aqueous dispersion.
• the aqueous medium contained in the aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) may be water alone, or may be a mixed solvent of water and a water-compatible organic solvent.
• the concentration of the water-compatible organic solvent is not particularly limited as long as it is equal to or lower than the solubility in water of the organic solvent used.
• the organic solvent is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, pentanol, hexanol, and heptanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; nitriles such as acetonitrile and propionitrile; amides such as dimethylformamide and acetamide; dimethyl sulfoxide, pyridine, and piperidine.
• alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, pentanol, hexanol, and heptanol
• ketones such as acetone and methyl ethyl ketone
• ethers
• methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, and propionitrile are preferred because they are easy to remove.
• methanol, ethanol, 1-propanol, 2-propanol, butanol, and acetone are more preferred because they are easily available.
• methanol, ethanol, and acetone are particularly preferred.
• the water content in the entire aqueous medium contained in the aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) is preferably 5% by weight or more, more preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, and particularly preferably 70% by weight or more. It may be 90% by weight or more, or 95% by weight or more. There is no particular upper limit, and it may be 100% by weight or less.
• the total concentration of the thermoplastic resin (A) and the crosslinked resin particles (B) in the aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) is not particularly limited, but is preferably 20% by weight or more, more preferably 30% by weight or more, and even more preferably 40% by weight or more, because it is economically advantageous in terms of drying utility and improves productivity.
• the upper limit of the total concentration is preferably 65% by weight or less, more preferably 60% by weight or less, in order to ensure the fluidity of the aqueous dispersion.
• the method of adjusting the total concentration is not particularly limited, and examples thereof include adding an aqueous medium and removing a part of the aqueous medium (for example, by removing the supernatant after centrifugation).
• the pH of the aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) is preferably adjusted to 8 or less, more preferably 7 or less, and more preferably 6 or less, as necessary, in order to suppress a decrease in the molecular weight of the resin component, for example, during spray drying and in the processing step after drying.
• the lower limit of the pH is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, from the viewpoint of the acid resistance of the container.
• the method of adjusting the pH and examples include a method of adding an acid.
• the acid may be either an organic acid or an inorganic acid. More specifically, examples of the acid that can be used include sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid.
• the aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) may contain one or more of the following, provided that the effects of the invention are not impaired: dispersants or emulsifiers, pH adjusters, inorganic fillers, colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolite, fragrances such as vanillin and dextrin, plasticizers, antioxidants, weather resistance improvers, ultraviolet absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and sliding property improvers. Furthermore, the aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) may contain various components resulting from the process of the production method, as long as the effects of the invention are not impaired.
• thermoplastic resin (A) and crosslinked resin particles (B) are the main components.
• the total proportion of the thermoplastic resin (A) and the crosslinked resin particles (B) in the total solid content of the aqueous dispersion may usually be 60 to 100% by weight, 80 to 100% by weight, 90 to 100% by weight, 95 to 100% by weight, or 99 to 100% by weight.
• the upper limit may be 99% by weight or less, or 95% by weight or less.
• the resin powder according to this embodiment can be suitably produced by spray-drying the aqueous dispersion containing the thermoplastic resin (A) and the crosslinked resin particles (B) described above.
• the spray drying method include a method in which the aqueous dispersion is supplied in the form of fine droplets into a dryer and dried while contacting with hot air in the dryer.
• the method of supplying the aqueous dispersion in the form of fine droplets into the dryer (atomizer) is not particularly limited, and includes known methods such as a method using a rotating disk and a method using a nozzle.
• the contact method between the droplets and hot air in the dryer is not particularly limited, and includes a parallel flow method, a countercurrent method, and a method using both of these.
• the drying temperature during spray drying may be any temperature that can remove most of the aqueous medium from the droplets of the aqueous dispersion. It can be set appropriately under conditions that allow drying to the desired moisture content and minimize the occurrence of quality deterioration (reduction in molecular weight, loss of color, etc.) and melting.
• the temperature of the hot air blown into the spray dryer can be selected appropriately within the range of 40 to 300°C.
• the volume of hot air inside the dryer can also be set appropriately depending on, for example, the size of the dryer.
• the use of the resin powder according to the present embodiment is not particularly limited, and it can be used in the applications in which conventionally known crosslinked resin particles are used.
• Specific examples include, but are not limited to, resin modifiers, rheology adjusters for paints or adhesives, paint pigments, paper coating agents, matting agents, antiblocking agents, cosmetic additives, toner additives, liquid crystal spacers, coating agents, fillers for adhesive tapes, fiber processing agents, medical diagnostic test particles, and fillers.
• the resin powder according to this embodiment may be processed into articles other than the powder.
• Such articles are not particularly limited, but include, for example, granules and molded articles described below.
• one aspect of the present disclosure extends to a resin composition containing a thermoplastic resin (A) and crosslinked resin particles (B), in which the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin and have a gel fraction of 50% or more. Details of the thermoplastic resin (A) and the crosslinked resin particles (B) and the content ratio of both components may follow the description above.
• the shape of the granules processed from the resin composition according to the present disclosure is not particularly limited, and may be, for example, approximately spherical, flat, cubic, spindle-shaped, needle-shaped, etc.
• the median diameter of the granules is not particularly limited, and may be, for example, about 1 mm to 10 mm.
• the granules may be pellets.
• the resin powder according to this embodiment When the resin powder according to this embodiment is processed into granules, there is an advantage in that it prevents classification when mixing with other thermoplastic resins described below in pellet form, and prevents the resin powder from clinging to the screw in a kneader.
• Examples of manufacturing methods for processing the resin powder according to this embodiment into granules include, but are not limited to, a method in which the resin powder is melted and extruded using an extruder, and then cut with a blade.
• a molded body can be produced from the resin powder according to this embodiment.
• the molded body is expected to have improved mechanical properties such as impact resistance.
• a molded body may be produced using only the resin powder according to this embodiment, or a molded body may be produced after mixing with optional additives and/or other thermoplastic resins. When mixing with optional additives and other thermoplastic resins, it is preferable to produce a molded body after obtaining a thermoplastic resin composition by a melt-kneading process.
• thermoplastic resin composition can be produced by a known method. Specifically, the resin powder according to this embodiment and any additives and/or other thermoplastic resins can be melt-kneaded using an extruder, kneader, Banbury mixer, kneading roll, or the like. When melt-kneading, it is preferable to mix while taking care not to reduce the molecular weight due to thermal decomposition.
• the thermoplastic resin composition can also be produced by dissolving each component in a soluble solvent and then removing the solvent.
• thermoplastic resin As the other thermoplastic resin, the resins exemplified for thermoplastic resin (A) can be used. The same resin as thermoplastic resin (A) may be used, or a different resin may be used.
• the optional additive may contain the resin powder according to this embodiment, or the additives described above may be used.
• each component When manufacturing by melt kneading, each component may be fed separately into an extruder, etc., or each component may be mixed in advance and then fed into an extruder, etc.
• the resulting thermoplastic resin composition may be extruded into strands and then cut to process into particle shapes such as bars, cylinders, elliptical cylinders, spheres, cubes, rectangular prisms, etc.
• the resin temperature during melt kneading cannot be generally defined because it depends on the melting point and melt viscosity of the resin used, but from the viewpoint of uniformly dispersing the crosslinked resin particles (B) while avoiding thermal decomposition of the thermoplastic resin (A) and the other thermoplastic resins, it is preferably 140 to 250°C, more preferably 150 to 230°C, and even more preferably 160 to 220°C.
• the molding method is not particularly limited, and any commonly used molding method can be applied, specifically including inflation film molding, extrusion blow molding, injection blow molding, extrusion molding, calendar molding, vacuum molding, injection molding, etc. These molding methods can be used to produce, for example, sheets, films, blow molded products, extrusion molded products, vacuum molded products, and injection molded products.
• the molded bodies formed from the resin powder according to this embodiment can be suitably used in the fields of agriculture, fishing, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and other fields.
• a resin powder having a median diameter of 20 to 1000 ⁇ m contains a thermoplastic resin (A) and crosslinked resin particles (B),
• the crosslinked resin particles (B) contain a polyhydroxyalkanoate resin, have a gel fraction of 50% or more, and have a volume average particle diameter of 0.1 ⁇ m or more and 10 ⁇ m or less. Resin powder.
• a resin powder according to item 1 wherein the content of the crosslinked resin particles (B) is 10 to 90% by weight in the total of the thermoplastic resin (A) and the crosslinked resin particles (B).
• thermoplastic resin (A) comprises a biodegradable resin.
• thermoplastic resin (A) comprises a biodegradable resin.
• biodegradable resin is a polyester-based resin.
• a method for producing the resin powder according to any one of items 1 to 8, A method of making a polymerizable composition comprising the steps of: preparing an aqueous dispersion comprising a thermoplastic resin (A) and crosslinked resin particles (B); and spray drying the aqueous dispersion.
• volume average particle diameter The volume average particle diameter of the crosslinked resin particles or the uncrosslinked resin particles was measured in the state of the resin particle latex.
• the measuring device used was a Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.
• the contents in the autoclave were stirred at room temperature for 1 hour to allow the peroxide and the polyfunctional compound to be impregnated into the uncrosslinked resin particles, and then the temperature was raised to the reaction temperature of 75° C. After the reaction temperature was reached, the reaction was continued for 3.5 hours at the reaction temperature, thereby obtaining an aqueous dispersion in which the crosslinked resin particles (B) were dispersed in water.
• the volume average particle size of the crosslinked resin particles (B) in the aqueous dispersion was measured by the above-mentioned method and was found to be 1.7 ⁇ m.
• the solidified crosslinked resin particles (B) were obtained by drying in an oven. The gel fraction of the particles was measured by the above-mentioned method and was found to be 95%.
• thermoplastic resin (A) solids concentration: 50%
• Thermoplastic resin (A): 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, volume average particle size: 2.2 ⁇ m
• Aqueous dispersion (a) and aqueous dispersion (b) were mixed in the ratio (based on solids weight) shown in Table 1, and the temperature was raised to approximately 50-55°C. The pH was then adjusted until it stabilized at 3.8, yielding a mixed aqueous dispersion.
• the median diameter of the resin powder obtained by spray drying was measured in a dry state using the laser diffraction/scattering method with an LMS-3000 manufactured by Seishin Enterprise Co., Ltd. The results are shown in Table 1.
• thermoplastic resin (A) and crosslinked resin particles (B) were obtained by spray drying an aqueous dispersion containing thermoplastic resin (A) and crosslinked resin particles (B).
• the resin powder obtained in each Example had good handleability.
• Comparative Example 1 (not shown in the table), spray drying of an aqueous dispersion containing only crosslinked resin particles (B) was attempted, but the resin particles adhered to the inner wall of the spray dryer while agglomerating, making recovery difficult, and it was impossible to obtain a resin powder like that obtained in each Example.

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