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
  • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
  • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
  • C08J3/075—Macromolecular gels
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
• • 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
  • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
• • 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
  • C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones

Definitions

• the present invention relates to crosslinked resin particles and a method for producing the same.
• Acrylic resins acrylic silicone resins, polystyrene, and the like are known as resin materials constituting such crosslinked resin particles (see, for example, Patent Documents 1 and 2).
• plastic waste is causing a burden on the global environment, including its impact on the ecosystem, the generation of harmful gases during combustion, and global warming due to the large amount of heat generated by combustion.As a material that can solve this problem, Development of biodegradable plastics is gaining momentum.
• Patent Document 3 describes that poly(3-hydroxyalkanoate), which is a type of biodegradable plastic, is melt-kneaded in the presence of an organic peroxide to crosslink the resin. .
• the cross-linked resin produced by melt-kneading in this way is used to construct films and sheets, and there is no mention at all of the production of small-sized cross-linked resin particles. .
• the present invention aims to provide novel crosslinked resin particles having biodegradability.
• the present invention relates to crosslinked resin particles containing a polyhydroxyalkanoate resin, having 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 an aqueous dispersion in which the crosslinked resin particles are dispersed in an aqueous medium.
• the present invention provides a method for producing the crosslinked resin particles, wherein the polyhydroxyalkanoate resin is crosslinked in the presence of a peroxide in an aqueous dispersion of the polyhydroxyalkanoate resin particles. It also relates to a manufacturing method including a step of causing.
• novel crosslinked resin particles having biodegradability can be provided.
• the crosslinked resin particles according to this embodiment are particles composed of a polyhydroxyalkanoate resin as a main resin component.
• polyhydroxyalkanoate resin may be abbreviated as "PHA”.
• PHA is a general term for polymers containing hydroxyalkanoic acids as monomer units, and is generally biodegradable.
• PHA is an aliphatic polyester, preferably a polyester containing no aromatic rings.
• the PHA is not particularly limited, but includes, for example, polyglycolic acid, poly(3-hydroxyalkanoate) resin, poly(4-hydroxyalkanoate) resin, and the like. As PHA, only one type may be used, or two or more types may be used in combination. Among these, poly(3-hydroxyalkanoate) resins are preferred. Hereinafter, poly(3-hydroxyalkanoate) resin may be abbreviated as "P3HA".
• the P3HA is 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 1 or more is an integer of 15 or less) as an essential repeating unit.
• the P3HA preferably contains the 3-hydroxyalkanoic acid repeating unit in an amount of 50 mol% or more of the total monomer repeating units (100 mol%), more preferably 70 mol% or more.
• P3HA is not particularly limited, but examples include poly(3-hydroxybutyrate) (abbreviation: P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), etc. .
• P3HA poly(3-hydroxybutyrate)
• P3HB3HH poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)
• P3HA3HH poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)
• P3HA can be produced by microorganisms. Such microorganism-produced P3HA is usually P3HA composed only of D-form (R-form) hydroxyalkanoic acid repeating units. Among microorganism-produced P3HA, P3HB and P3HB3HH are preferred, and P3HB3HH is more preferred, since industrial production is easy.
• the composition ratio of 3HB repeating units is 60 to 99 mol% in all monomer repeating units (100 mol%) from the viewpoint of balance between flexibility and strength. It is preferably 65 to 97 mol%, and even more preferably 67 to 95 mol%.
• the composition ratio of 3HB repeating units is 60 mol% or more, the rigidity of the crosslinked resin particles can be further improved.
• the composition ratio of 3HB repeating units is 99 mol % or less, the flexibility of the crosslinked resin particles tends to be further improved.
• the monomer composition ratio of P3HA can be measured by gas chromatography or the like (for example, see International Publication No. 2014/020838). As P3HA, two or more types having mutually different composition ratios of 3HB repeating units may be used in combination.
• the microorganism that produces P3HA is not particularly limited as long as it has the ability to produce P3HA.
• the first P3HB-producing bacterium was Bacillus megaterium, which was discovered in 1925, and other bacteria include Cupriavidus necator (former classification: Alcaligenes eutrophus), Ralstonia eutrophus Hua (Ralstonia eutropha)) , Alcaligenes latus and other natural microorganisms are known. In these microorganisms, P3HB accumulates inside the cells.
• Aeromonas caviae which is a P3HB3HH producing bacterium
• Aeromonas caviae which is a P3HB3HH producing bacterium
• a producing bacterium of copolymers of 3HB and other hydroxyalkanoates in particular, in order to increase the productivity of P3HB3HH, the Alcaligenes eutrophus AC32 strain (FERM BP-6038) into which genes of the P3HA synthetase group were introduced (T. Fukui, Y. Doi, J. Bateriol., 17 9 , p. 4821-4830 (1997)) is preferred. Microbial cells obtained by culturing such microorganisms under appropriate conditions and accumulating P3HA inside 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, and culture conditions including the type of substrate may be optimized, depending on the P3HA to be produced.
• the molecular weight of PHA is not particularly limited, but the weight average molecular weight is preferably 50,000 to 3,000,000, preferably 100,000 to 2,000,000, and preferably 150,000 to 1,500,000. More preferred. By setting the weight average molecular weight to 50,000 or more, it is possible to avoid a tendency for the strength of the crosslinked resin particles to decrease, or to avoid a tendency for the crosslinked resin particles to become sticky due to low molecular weight components. On the other hand, PHAs with weight average molecular weights exceeding 3,000,000 may be difficult to produce themselves or to handle for purposes of the present invention.
• the numerical value of the weight average molecular weight is a value measured before performing the crosslinking treatment of PHA.
• the method for measuring the weight average molecular weight is to use gel permeation chromatography (GPC) ("High Performance Liquid Chromatograph 20A System” manufactured by Shimadzu Corporation) and use polystyrene gel ("K-G 4A", "K -806M, etc.), using chloroform as a mobile phase, and calculating the molecular weight in terms of polystyrene.
• GPC gel permeation chromatography
• K-G 4A "K -806M, etc.
• the calibration curve can be created using polystyrene having weight average molecular weights of 31,400, 197,000, 668,000, and 1,920,000.
• a column suitable for measuring the molecular weight may be used as a column in the GPC.
• the crosslinked resin particles according to this embodiment have a crosslinked structure in which molecular chains of PHA are bonded to each other. Since the crosslinked resin particles have a certain amount or more of such a crosslinked structure, the crosslinked resin particles according to the present embodiment exhibit a high gel fraction, specifically, a gel fraction of 50% or more. By exhibiting such a high gel fraction, the hardness, heat resistance, solvent resistance, etc. of the resin particles containing PHA can be improved.
• the value of 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. Further, it may be 85% or more, or 90% or more.
• the upper limit of the gel fraction is not particularly limited and may be 100% or less, but from the viewpoint of production efficiency of crosslinked resin particles, it is preferably 99.5% or less, more preferably 99% or less. Moreover, it may be 98% or less, 97% or less, or 96% or less.
• the gel fraction is a value measured as follows. Dry crosslinked resin particles are added to chloroform at a concentration of 0.7% by weight, and dissolved at 60° C. for 30 minutes to obtain a chloroform solution. After that, the chloroform solution is left to stand at room temperature for 3 hours, and then filtered through a membrane filter with a pore size of 0.45 ⁇ m. The gel remaining on the filter is dried and weighed together with the filter, and the gel fraction is calculated using the following formula.
• Gel fraction (weight of filter containing dry gel - weight of filter only) / weight of crosslinked resin particles used for measurement x 100 (%)
• the crosslinked resin particles according to this embodiment have a volume average particle diameter within a range of 0.1 ⁇ m or more and 10 ⁇ m or less. By having such a particle size, it becomes possible to use it for various purposes as described below.
• the lower limit of the particle size is preferably 0.1 ⁇ m or more, more preferably 0.3 ⁇ m or more, and even more preferably 0.5 ⁇ m or more, from the viewpoint of practical use opportunities.
• the upper limit of the particle size is preferably 8 ⁇ m or less, more preferably 5 ⁇ m or less.
• the volume average particle diameter is a value measured in a state where crosslinked resin particles are dispersed in an aqueous solvent.
• a general-purpose measuring device can be used, and an example of such a device is Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.
• the type of crosslinking in the crosslinked resin particles according to this embodiment is not particularly limited, it is preferable that the particles be crosslinked using a peroxide.
• peroxide radicals generated by decomposition of peroxide act on PHA molecules, and the PHA molecular chains are directly bonded 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.
• the organic peroxide may include diacyl peroxide, alkyl peroxy ester, dialkyl peroxide, hydroperoxide, peroxy ketal, peroxy carbonate, and peroxy, taking into account the heating temperature and time during crosslinking treatment. It is preferred to use at least one selected from the group consisting of dicarbonates.
• organic peroxides include butyl peroxyneododecanoate, octanoyl peroxide, dilauroyl peroxide, succinic peroxide, a mixture of toluoyl peroxide and benzoyl peroxide, and benzoyl peroxide.
• t-butylperoxyisopropyl monocarbonate t-pentylperoxyisopropyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-pentylperoxy 2-ethylhexyl Monocarbonate, t-hexylperoxy 2-ethylhexyl monocarbonate, t-amylperoxyisopropyl monocarbonate, di-t-hexyl peroxide, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyl rate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-he
• the peroxide is preferably a compound whose 1-hour half-life temperature is 200°C or lower, more preferably 170°C or lower, and 140°C or lower, since the heating temperature during crosslinking treatment can be set low. It is even more preferable that there be.
• the lower limit may be 50°C or higher, 60°C or higher, or 70°C or higher.
• Organic peroxides exhibiting such a 1-hour half-life temperature include t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, di-sec-butylperoxydicarbonate, and t-butylperoxy.
• the inorganic peroxide may be, for example, hydrogen peroxide, potassium peroxide, calcium peroxide, or Examples include sodium, magnesium peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, and the like.
• hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate are preferred because they are easy to handle and have a decomposition temperature suitable for the heating temperature during crosslinking treatment.
• One type of inorganic peroxide may be used alone, or two or more types may be used in combination. Further, organic peroxides and inorganic peroxides may be used in combination.
• the crosslinked structure in the crosslinked resin particles according to this embodiment may be introduced using only peroxide, but it may be introduced using both peroxide and a polyfunctional compound. It's okay. The latter makes it possible to increase the gel fraction of crosslinked resin particles with a smaller amount of peroxide.
• the polyfunctional compound refers to a compound that has two or more functional groups in one molecule that can crosslink PHA.
• compounds having reactivity with radicals generated from peroxides are preferred, and compounds having two or more radical-reactive groups in one molecule are 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 include, for example, allyl (meth)acrylate; allyl alkyl (meth) acrylates; allyloxyalkyl (meth) acrylates; ethylene glycol di (meth) acrylate, butane diol di (meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, etc.
• Polyfunctional (meth)acrylates having two or more meth)acrylic groups examples include divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene.
• examples include 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.
• the resulting crosslinked resin particles can usually contain a structure derived from the polyfunctional compound.
• the molecular chains of PHA are bonded to each other via a structure derived from the polyfunctional compound.
• the crosslinked resin particles according to the present embodiment 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, and the like.
• the proportion of PHA in the crosslinked resin particles according to the present embodiment 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, and more preferably 90% by weight or more. It is more preferable, and 95% by weight or more is particularly preferable. It may be 99% by weight or more.
• the upper limit is not particularly limited, as long as it is 100% by weight or less.
• resins other than PHA include aliphatic polyesters having a structure in which aliphatic diols and aliphatic dicarboxylic acids are polycondensed, and aliphatic aromatic polyesters having both an aliphatic compound and an aromatic compound as monomers. It will be done.
• the former include polyethylene succinate, polybutylene succinate (PBS), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (PBSA), polyethylene sebacate, poly Examples include butylene 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), and poly(butylene succinate-co-butylene terephthalate). co-butylene terephthalate) (PBST).
• PBAT poly(butylene adipate-co-butylene terephthalate)
• PBST poly(butylene sebacate-co-butylene terephthalate)
• PBST co-butylene terephthalate
• the other resins may be used alone or in combination of two or more.
• the crosslinked resin particles according to the present embodiment are different from the foamed resin particles disclosed in International Publication No. 2007/049694 and International Publication No. 2019/146555, and are not foamed. That is, it is preferable that the particles do not substantially contain air bubbles inside the particles.
• the apparent density of the crosslinked resin particles according to this embodiment exhibits a relatively large value, preferably exceeding 0.6 g/cm 3 , more preferably 0.7 g/cm 3 or more. , more preferably 0.9 g/cm 3 or more.
• the apparent density of the crosslinked resin particles 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 according to the present embodiment is not particularly limited, but since the crosslinked resin particles have a small volume average particle size of 10 ⁇ m or less, the weight is far less than 0.1 mg. It is.
• the crosslinked resin particles according to this embodiment may be dried.
• the shape after drying can be powder, pellet, crumb, sheet, etc. depending on the drying method.
• One aspect of this embodiment may be an aqueous dispersion in which the crosslinked resin particles are dispersed in an aqueous medium.
• the aqueous medium contained in the aqueous dispersion may be only water, or may be a mixed solvent of water and an organic solvent that is compatible with water.
• the concentration of the water-compatible organic solvent is not particularly limited as long as it is below the solubility of the organic solvent used in water.
• the organic solvent is not particularly limited, but includes, for example, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, pentanol, hexanol, and heptanol; acetone, methyl ethyl ketone, etc. Ketones such as; 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
• acetone methyl ethyl ketone
• Ketones
• methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, propionitrile and the like are preferred from the standpoint of easy removal.
• methanol, ethanol, 1-propanol, 2-propanol, butanol, acetone, etc. are more preferred because they are easily available.
• methanol, ethanol and acetone are particularly preferred.
• the content of water in the entire aqueous medium constituting the aqueous dispersion is preferably 5 to 100% by weight, preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, and 70% by weight or more. Particularly preferably % by weight or more. It may be 90% by weight or more, or 95% by weight or more.
• the concentration of the crosslinked resin particles in the aqueous dispersion is not particularly limited, but may be, for example, about 1 to 60% by weight. Further, the aqueous dispersion may contain a dispersant described below.
• the crosslinked resin particles according to this embodiment can be produced by crosslinking PHA in the presence of peroxide in an aqueous dispersion containing PHA particles before crosslinking treatment.
• the method for producing crosslinked resin particles includes a step (1) of preparing an aqueous dispersion of PHA particles in which PHA particles before crosslinking treatment are dispersed in water; A step (2) of adding an oxide to impregnate the PHA particles with the peroxide, and a step (3) of crosslinking the PHA by heating the aqueous dispersion of the PHA particles impregnated with the peroxide to a heating temperature. It is preferable to include. Furthermore, it is more preferable to include a step (4) of maintaining the heating temperature after all the peroxide is added.
• the aqueous dispersion of PHA particles is prepared by culturing PHA-producing microorganisms to accumulate PHA in the microbial cells, and then destroying the microbial cells in the culture solution and separating and removing the bacterial components.
• the aqueous dispersion may be the obtained aqueous dispersion, 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 PHA-producing microorganisms to crosslinking treatment can be carried out without separating the PHA particles from water.
• an aqueous dispersion of PHA particles can also be prepared by dispersing dried PHA particles in water.
• the aqueous dispersion may contain, in addition to water, the above-mentioned organic solvent that is compatible with water.
• 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 described above.
• the volume average particle size can usually be within the above range, so a desired volume average particle size can be achieved without implementing a special process to adjust the particle size.
• An aqueous dispersion of PHA particles can be obtained.
• the concentration of PHA particles in the aqueous dispersion is not particularly limited and can be set as appropriate, but may be, for example, about 1 to 70% by weight, preferably about 5 to 50% by weight.
• the aqueous dispersion of PHA particles preferably contains a dispersant in order to improve the dispersibility of the PHA particles and 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 trimethylammonium chloride; glycerin fatty acid ester, sorbitan fatty acid ester.
• nonionic surfactants such as sucrose fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polyoxypropylene glycol; polyvinyl alcohol, ethylene-modified polyvinyl alcohol, polyvinylpyrrolidone, methylcellulose, ethylcellulose, Examples include water-soluble polymers such as hydroxymethyl cellulose, hydroxyethyl cellulose, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polymethacrylic acid, and sodium polymethacrylate. These dispersants may be used alone or in combination of two or more.
• 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, based on 100 parts by weight of PHA particles. , 0.5 to 3 parts by weight are particularly preferred.
• step (2) peroxide is added to the aqueous dispersion of PHA particles obtained in step (1) to impregnate the PHA particles with peroxide.
• peroxide those mentioned above can be used.
• Peroxide can be added in various forms such as solid or liquid. Alternatively, a liquid diluted with a diluent or the like may be added. Peroxide may be added all at once, continuously or in portions.
• the polyfunctional compound is also added to the aqueous dispersion of PHA particles in this step (2).
• the polyfunctional compound those mentioned above can be used.
• the polyfunctional compound can be added in various forms such as solid or liquid. Alternatively, a liquid diluted with a diluent or the like may be added.
• the polyfunctional compound may be added all at once, continuously or in portions.
• the temperature of the aqueous dispersion is increased, e.g.
• the temperature may be set below a temperature suitable for decomposing the peroxide used in the next step (3), and the temperature may be maintained, for example, for about 1 minute to 5 hours while stirring the aqueous dispersion.
• the temperature of the aqueous dispersion during impregnation may be about 10 to 60°C.
• the amount of peroxide to be used can be appropriately set in consideration of the gel fraction of the crosslinked resin particles, but for example, it is preferably 0.01 to 10 parts by weight based on 100 parts by weight of PHA particles. It is 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.
• the amount of the polyfunctional compound to be used may be appropriately determined in consideration of the gel fraction of the crosslinked resin particles, and is preferably 0.01 to 20 parts by weight based on 100 parts by weight of the PHA particles. , 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.
• 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 and below the 1-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, since it is possible to crosslink PHA at a temperature lower than the melting temperature of PHA, it is possible to avoid deterioration of PHA due to heating during crosslinking treatment.
• the heating temperature is not particularly limited, but is preferably from 1 minute to 15 hours, more preferably from 1 hour to 10 hours.
• dry crosslinked resin particles can be obtained by separating the crosslinked resin particles from the aqueous dispersion and removing water.
• the method for separating crosslinked resin particles is not particularly limited, and for example, filtration, centrifugation, heat drying, freeze drying, spray drying, etc. can be used.
• spray drying can be used to obtain dried crosslinked resin particles directly from an aqueous dispersion.
• by extruding the crosslinked resin particles alone after separation from the aqueous dispersion it is possible to completely remove residual moisture and obtain crosslinked resin particles in the form of pellets.
• a coagulation step using a coagulant or pH adjustment may be carried out.
• aqueous dispersion itself after the completion of the crosslinking reaction, the aqueous dispersion obtained by concentrating the aqueous dispersion after the completion of the crosslinking reaction to increase the concentration of crosslinked resin particles, or the aqueous dispersion after the completion of the crosslinking reaction,
• An aqueous dispersion diluted with the addition of a medium also constitutes an aspect of the present invention.
• crosslinked resin particles The use of the crosslinked resin particles according to this embodiment is not particularly limited, and can be used in any use in which conventionally known crosslinked resin particles are used.
• resin modifiers, rheology modifiers for paints or adhesives, paint pigments, paper coating agents, matting agents, anti-blocking agents, cosmetic additives, toner additives, spacers for liquid crystals, and coatings examples include, but are not limited to, agents, fillers for adhesive tapes, fiber processing agents, test particles for medical diagnosis, fillers, and the like.
• crosslinked resin particles according to the present embodiment are composed of biodegradable PHA, they are expected to be useful as crosslinked resin particles that are environmentally friendly and address the issue of plastic waste.
• [Item 1] Contains polyhydroxyalkanoate resin, Crosslinked resin particles having a gel fraction of 50% or more and a volume average particle diameter of 0.1 ⁇ m or more and 10 ⁇ m or less.
• [Item 2] The crosslinked resin particles according to item 1, wherein the polyhydroxyalkanoate-based resin is a poly(3-hydroxyalkanoate)-based resin.
• [Item 3] The crosslinked resin particles according to item 1 or 2, wherein the crosslinked resin particles are crosslinked using a peroxide.
• [Item 4] The crosslinked resin particles according to any one of items 1 to 3, wherein the crosslinked resin particles are further crosslinked in the presence of a polyfunctional compound.
• [Item 5] The crosslinked resin particles according to any one of items 1 to 4, wherein the crosslinked resin particles are not foamed.
• [Item 6] The crosslinked resin particles according to any one of items 1 to 5, wherein the proportion of the polyhydroxyalkanoate resin in the crosslinked resin particles is 80% by weight or more.
• [Item 7] Crosslinked resin particles according to any one of items 1 to 6, wherein the gel fraction is 70 to 100%.
• [Item 8] An aqueous dispersion in which the crosslinked resin particles according to any one of items 1 to 7 are dispersed in an aqueous medium.
• volume average Particle Diameter The volume average particle diameter of the crosslinked resin particles or base resin particles was measured in the state of resin particle latex. As a measuring device, Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. was used.
• the contents in the autoclave were stirred at the temperature and time specified in the impregnation conditions listed in the table to impregnate the peroxide and the polyfunctional compound into the base resin particles, and then the crosslinking conditions specified in the table were applied.
• the temperature was raised to the reaction temperature.
• the reaction was carried out at the reaction temperature for the reaction time under the crosslinking conditions listed in the table to obtain an aqueous dispersion in which crosslinked resin particles were dispersed in water.
• After adjusting the pH of the aqueous dispersion it was dried in an oven to obtain solidified crosslinked resin particles.
• the volume average particle diameter and gel fraction of the crosslinked resin particles obtained in each example were measured by the above-mentioned method, and the results are shown in the table.

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• 2023
  • 2023-03-24 JP JP2024512369A patent/JPWO2023190183A1/ja active Pending
  • 2023-03-24 WO PCT/JP2023/011870 patent/WO2023190183A1/ja not_active Ceased
  • 2023-03-24 US US18/850,708 patent/US20250230273A1/en active Pending
  • 2023-03-24 EP EP23780193.1A patent/EP4506395A4/en active Pending
  • 2023-03-24 CN CN202380029876.6A patent/CN118922477A/zh active Pending

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