Resin particles

Abstract

A resin particle having a parent particle containing a biodegradable resin, wherein the amount of alkali metal atoms A present in the surface of the resin particle relative to the total amount of atoms present in the surface of the resin particle, measured by X-ray photoelectron spectroscopy, and the amount of alkali metal atoms B present in the resin particle relative to the total amount of atoms present in the resin particle, measured by X-ray fluorescence spectroscopy, satisfy the relationship 0 ≤ (A / B) < 0.15 and 0.005 atomic% ≤ B ≤ 0.5 atomic%.

Description

Technical Field

[0001] This invention relates to a resin particle. Background Technology

[0002] Patent Document 1 discloses "a biodegradable resin composition, characterized in that it comprises a recalcitrant biodegradable resin (A), an ester decomposition promoter (B) composed of an easily hydrolyzable polymer, and an ester decomposition promoting aid (C) composed of inorganic particles that promotes the hydrolysis of the ester decomposition promoter, wherein the biodegradable resin (A) contains 0.01 to 30 parts by weight of the ester decomposition promoter (B) per 100 parts by weight, and the ester decomposition promoter (B) contains 28 to 200 parts by weight of the ester decomposition promoting aid (C) per 100 parts by weight."

[0003] Patent document 2 discloses "a biodegradable resin composition, characterized in that it comprises polylactic acid (A), polyglycolic acid (B), and calcium carbonate particles (C) as an ester decomposition promoter, wherein the content of polyglycolic acid (B) is 1 to 10 parts by weight relative to 100 parts by weight of polylactic acid (A), and the content of calcium carbonate particles (C) is 30 to 100 parts by weight relative to 100 parts by weight of polyglycolic acid (B)."

[0004] Patent document 3 proposes "a resin composition characterized in that it contains a biodegradable polyester resin and a compound NaX(1) represented by general formula (1) as a nucleating agent (where X represents a halogen atom), wherein the compound represented by general formula (1) is dispersed in the polyester resin in the form of particles with an average particle size of less than 10 μm."

[0005] Patent Document 1: Japanese Patent No. 5633291

[0006] Patent Document 2: Japanese Patent No. 5829393

[0007] Patent Document 3: Japanese Patent Application Publication No. 2009-249577 Summary of the Invention

[0008] The subject of this invention is the situation in which the amount of alkali metal atoms A present on the surface of resin particles having parent particles containing biodegradable resin, relative to the total atomic mass present on the surface of the resin particles as measured by X-ray photoelectron spectroscopy, and the amount of alkali metal atoms B present on the surface of the resin particles relative to the total atomic mass present on the resin particles as measured by X-ray fluorescence spectroscopy, satisfy the relationship (A / B) > 0.15, 0.005 atomic% > B, or B > 0.5 atomic%; or the amount of alkali metal atoms B present relative to the total atomic mass present on the surface of the resin particles as measured by X-ray photoelectron spectroscopy. Compared to the cases where the atomic weight of alkali metals on the surface of resin particles is [AL1], the atomic weight of alkali metals on the surface of resin particles after etching a 2 mm square area on the surface of resin particles with an argon cluster ion gun with an output of 5 kV for 5 minutes [AL2], and the atomic weight of alkali metals on the surface of resin particles after etching a 2 mm square area on the surface of resin particles with an argon cluster ion gun with an output of 5 kV for 30 minutes [AL3], resin particles with excellent biodegradability and storage properties in aqueous solutions can be obtained.

[0009] The above-mentioned problem was solved through the following solution. That is,

[0010] <1> A resin particle having a parent particle containing a biodegradable resin, wherein,

[0011] The alkali metal atomic weight A on the surface of resin particles, measured by X-ray photoelectron spectroscopy relative to the total atomic weight present on the surface of resin particles, and the alkali metal atomic weight B on the surface of resin particles, measured by X-ray fluorescence spectroscopy relative to the total atomic weight present on the surface of resin particles, satisfy the relationship that 0 ≤ (A / B) < 0.15 and 0.005atomic% ≤ B ≤ 0.5atomic%.

[0012] <2> The resin particles according to <1>, wherein the alkali metal comprises Na.

[0013] <3> The resin particles according to <1> or <2>, wherein the content of cellulose acylate is 50% by mass or more relative to the total amount of the parent particles.

[0014] <4> According to the resin particles described in <3>, wherein the cellulose acylated compound is a cellulose acylated compound having at least two or more acyl groups.

[0015] <5> According to the resin particles described in <4>, the cellulose acylated product having at least two or more acyl groups is cellulose acetate butyrate.

[0016] <6> The resin particles according to any one of <1> to <5> have, in sequence, the following on the surface of the parent particle:

[0017] The first layer comprises at least one cationic resin selected from polyalkyleneimide, polyacrylamide, and polyethyleneimine; and

[0018] The second layer contains anionic or nonionic hydrophilic compounds.

[0019] <7> According to the resin particles described in <6>, the coating amount based on the first layer is more than 0.01% by mass and less than 20% by mass relative to the total amount of the parent particles.

[0020] <8> A resin particle having a parent particle containing a biodegradable resin, wherein,

[0021] The alkali metal atomic weights were measured by X-ray photoelectron spectroscopy, and the alkali metal atomic weights on the surface of the resin particles [AL1], the alkali metal atomic weights on the surface of the resin particles after etching a 2 mm square area of ​​the resin particle surface with an argon cluster ion gun with an output of 5 kV for 5 minutes [AL2], and the alkali metal atomic weights on the surface of the resin particles after etching a 2 mm square area of ​​the resin particle surface with an argon cluster ion gun with an output of 5 kV for 30 minutes [AL3] satisfy the relationship [AL1]<[AL3]<[AL2].

[0022] Invention Effects

[0023] According to the invention described in <1>, a resin particle is provided that, compared to the case where the amount of alkali metal atoms A present on the surface of the resin particle relative to the total atomic mass present on the surface of the resin particle, as measured by X-ray photoelectron spectroscopy, and the amount of alkali metal atoms B present in the resin particle relative to the total atomic mass present on the surface of the resin particle, as measured by X-ray fluorescence spectroscopy, satisfy the relationship (A / B)≥0.15, 0.005atomic%>B, or B>0.5atomic% in a parent particle containing a biodegradable resin particle, is biodegradable and has excellent shelf life in an aqueous solution.

[0024] According to the invention described in <2>, a resin particle is provided that has excellent biodegradability and storage properties in aqueous solutions compared to cases where the alkali metal contains alkali metal elements other than Na.

[0025] According to the invention described in <3>, a resin particle is provided that is biodegradable and has excellent storage properties in an aqueous solution compared to a case where the content of cellulose acylate is less than 50% by mass relative to the total amount of the parent particles.

[0026] According to the invention described in <4>, a resin particle is provided that has excellent biodegradability and excellent storage properties in aqueous solutions compared to the case where the cellulose acylate is a cellulose acylate having an acyl group.

[0027] According to the invention described in <5>, a resin particle is provided that has excellent biodegradability and shelf life in aqueous solutions compared to the case where the cellulose acylate having at least two or more acyl groups is other than cellulose acetate butyrate.

[0028] According to the invention described in <6>, a resin particle is provided that, compared to a resin particle having a parent particle containing a biodegradable resin, wherein the amount of alkali metal atoms A present on the surface of the resin particle relative to the total atomic mass present on the surface of the resin particle, as measured by X-ray photoelectron spectroscopy, and the amount of alkali metal atoms B present on the surface of the resin particle relative to the total atomic mass present on the surface of the resin particle, as measured by X-ray fluorescence spectroscopy, satisfies the relationship 0 ≤ (A / B) < 0.15 and 0.005 atomic% ≤ B ≤ 0.5 atomic% in which the parent particle does not sequentially have a first layer containing at least one cationic resin selected from polyalkyleneimide, polyacrylamide, and polyethyleneamine, and a second layer containing anionic or nonionic hydrophobic compounds, has excellent biodegradability and shelf life in aqueous solutions.

[0029] According to the invention described in <7>, a resin particle is provided that, compared to a resin particle having sequentially formed on the surface of the parent particle a first layer comprising at least one cationic resin selected from polyalkylimide, polyacrylamide, and polyethyleneamine, and a second layer comprising anionic or nonionic hydrophobic compound, exhibits excellent biodegradability and shelf life in aqueous solutions, based on the case where the coating amount of the first layer is less than 0.01% by mass or more than 20% by mass relative to the total amount of the parent particle.

[0030] According to the invention described in <8>, a resin particle is provided that, compared to the case where the alkali metal atomic weight in a resin particle containing a parent particle of biodegradable resin is measured by X-ray photoelectron spectroscopy, and the alkali metal atomic weight [AL1] on the surface of the resin particle, the alkali metal atomic weight [AL2] on the surface of the resin particle after etching a 2 mm square area on the surface of the resin particle with an argon cluster ion gun with an output of 5 kV for 5 minutes, and the alkali metal atomic weight [AL3] on the surface of the resin particle after etching a 2 mm square area on the surface of the resin particle with an argon cluster ion gun with an output of 5 kV for 30 minutes satisfies [AL1] > [AL2] and [AL1] > [AL3], has excellent biodegradability and shelf life in an aqueous solution. Detailed Implementation

[0031] The following describes one example, or embodiment, of the present invention. These descriptions and examples are illustrative and do not limit the scope of the invention.

[0032] Within the numerical ranges described in this specification, the upper or lower limit value described as a single numerical range can be replaced with the upper or lower limit value of other numerical ranges described in different stages. Furthermore, within the numerical ranges described in this specification, the upper or lower limit value of the numerical range can be replaced with the values ​​shown in the embodiments.

[0033] Each component may contain multiple corresponding substances.

[0034] When referring to the amount of each component in a composition, if a plurality of substances corresponding to each component are present in the composition, it indicates the total amount of such plurality of substances present in the composition unless otherwise specified.

[0035] <Resin Particles>

[0036] The resin particles according to the first embodiment have parent particles containing biodegradable resin, and the alkali metal atomic mass A (hereinafter also simply "atomic mass A") present on the surface of the resin particles relative to the total atomic mass present on the surface of the resin particles, as measured by X-ray photoelectron spectroscopy, and the alkali metal atomic mass B (hereinafter also simply "atomic mass B") present on the surface of the resin particles relative to the total atomic mass present on the resin particles, as measured by X-ray fluorescence spectroscopy, satisfy the relationship 0 ≤ (A / B) < 0.15 and 0.005 atomic% ≤ B ≤ 0.5 atomic%.

[0037] Based on the above structure, the resin particles according to the first embodiment are biodegradable and have excellent storage properties in aqueous solutions. The reasons are as follows.

[0038] Resin particles containing biodegradable resins (hereinafter also referred to as biodegradable resin particles) are sometimes contained in aqueous solutions, depending on their intended use. However, biodegradable resin particles are readily hydrolyzed in aqueous solutions. Therefore, the shelf life of biodegradable resin particles in aqueous solutions is not adequate.

[0039] While the exact reasons are not yet clear, the presence of alkali metals in biodegradable resin particles tends to promote hydrolysis in aqueous solutions. Furthermore, the shelf life of biodegradable resin particles in aqueous solutions tends to depend on the ease of hydrolysis on the surface of the biodegradable resin particles. Therefore, the presence of alkali metals on the surface of biodegradable resin particles reduces their shelf life in aqueous solutions.

[0040] The atomic weights A and B of the resin particles involved in the first embodiment satisfy the relationship 0 ≤ (A / B) < 0.15 and 0.005 atomic% ≤ B ≤ 0.5 atomic% . Because the resin particles satisfy 0 ≤ (A / B) < 0.15, the amount of alkali metal present near the surface of the resin particles is reduced. Therefore, hydrolysis of the resin particle surface is less likely to occur. As a result, the shelf life in aqueous solutions is improved.

[0041] On the other hand, because the resin particles satisfy the relationship 0.005atomic% ≤ B ≤ 0.5atomic% and contain alkali metals, alkali metals also tend to promote the biodegradability of biodegradable resins, thereby ensuring the biodegradability of the resin particles.

[0042] Therefore, based on the above structure, it is estimated that the resin particles involved in the first embodiment are biodegradable and have excellent storage properties in aqueous solutions.

[0043] The resin particles involved in the second embodiment have parent particles containing biodegradable resin, and the atomic weight of alkali metals is measured by X-ray photoelectron spectroscopy. The atomic weight of alkali metals on the surface of the resin particles [AL1], the atomic weight of alkali metals on the surface of the resin particles after etching a 2 mm square area on the surface of the resin particles with an argon cluster ion gun with an output of 5 kV for 5 minutes [AL2], and the atomic weight of alkali metals on the surface of the resin particles after etching a 2 mm square area on the surface of the resin particles with an argon cluster ion gun with an output of 5 kV for 30 minutes [AL3] satisfy the relationship [AL1]<[AL3]<[AL2].

[0044] Based on the above structure, the resin particles involved in the second embodiment are biodegradable and have excellent storage properties in aqueous solutions. The reasons are as follows.

[0045] Here, [AL1] represents the atomic weight of alkali metals in the region near the surface of the resin particles, [AL2] represents the atomic weight of alkali metals in the region approximately 100 nm deep from the surface of the resin particles, and [AL3] represents the atomic weight of alkali metals in the region close to the center of the resin particles. Therefore, by satisfying the relationship [AL1] < [AL3] < [AL2], the amount of alkali metals present near the surface of the resin particles is minimized. This improves the storeability in aqueous solutions. Furthermore, by setting the atomic weight of alkali metals in the region approximately 100 nm deep from the surface of the resin particles to be the maximum, biodegradation is promoted when it reaches this region. Moreover, by setting the atomic weight of alkali metals in the region close to the center of the resin particles to be the second maximum, promoted biodegradation is easily ensured.

[0046] Therefore, based on the above structure, it is estimated that the resin particles involved in the second embodiment are biodegradable and have excellent storage properties in aqueous solutions.

[0047] Hereinafter, resin particles corresponding to the resin particles involved in the first or second embodiment will be described in detail. However, any example of the resin particles of the present invention may be any resin particle corresponding to any one of the resin particles involved in the first or second embodiment.

[0048] (mother particle)

[0049] -Biodegradable resin-

[0050] The parent particles contain biodegradable resin.

[0051] Parent particles may include particles that contain biodegradable resin as the main component, specifically particles that contain 90%, 95%, 98%, or 100% biodegradable resin relative to the total amount of parent particles.

[0052] Here, biodegradable resin refers to resin that is broken down into water and carbon dioxide by microorganisms. Specifically, biodegradable resin is defined as resin whose aerobic biodegradation rate, measured using a method based on ISO-14855-2 (2018), is greater than 50% within one month.

[0053] Examples of biodegradable resins include cellulose acylates, polyesters, and natural polymers.

[0054] Cellulose acylated products are cellulose derivatives in which at least a portion of the hydroxyl groups in cellulose are replaced (acylated) by acyl groups. The acyl group has a -CO-R group. AC (R AC A group representing a hydrogen atom or a hydrocarbon group. Examples of cellulose acylates include cellulose derivatives represented by the general formula (CA).

[0055] Examples of polyesters include aliphatic polyesters and aliphatic aromatic polyesters.

[0056] Examples of aliphatic polyesters include polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxybutyrate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), polycaprolactone, polybutylene succinate (PBS), polybutylene succinate / adipate (PBSA), and polyethylene glycol succinate (PBA), among other polyhydroxy fatty acid esters.

[0057] Examples of aliphatic aromatic polyesters include polybutylene adipate / terephthalate copolymer resin (PBAH) and polytetramethylene adipate / terephthalate copolymer resin.

[0058] Examples of natural macromolecules include starch, cellulose, chitin, chitosan, gluten, gelatin, casein, soy protein, collagen, and keratin.

[0059] From the viewpoint of improving biodegradability, cellulose acylates are preferred as biodegradable resins.

[0060] Cellulose acylates

[0061] Cellulose acylated compounds are, for example, cellulose derivatives represented by the following general formula (CA).

[0062] [Chemical Formula 1]

[0063]

[0064] In the general formula (CA), A1, A2, and A3 independently represent hydrogen atoms or acyl groups, and n represents an integer greater than 2. At least some of the n A1, n A2, and n A3 atoms represent acyl groups. The n A1 atoms in a molecule can be all identical, partially identical, or different from each other. Similarly, the n A2 atoms and n A3 atoms in a molecule can be all identical, partially identical, or different from each other.

[0065] In the acyl groups represented by A1, A2 and A3, the hydrocarbon group in the acyl group can be any one of straight chain, branched chain and cyclic, but is preferably straight chain or branched chain, and more preferably straight chain.

[0066] In the acyl groups represented by A1, A2 and A3, the hydrocarbon group in the acyl group can be a saturated hydrocarbon group or an unsaturated hydrocarbon group, but is more preferably a saturated hydrocarbon group, for example.

[0067] The acyl groups represented by A1, A2, and A3 are preferably acyl groups with one or more but no more than six carbon atoms. That is, as a cellulose acylated product, a cellulose acylated product with one or more but no more than six carbon atoms in the acyl group is preferred.

[0068] In the acyl groups represented by A1, A2, and A3, the hydrogen atom in the acyl group can be replaced by a halogen atom (e.g., a fluorine atom, a bromine atom, an iodine atom), an oxygen atom, a nitrogen atom, etc., but is preferably unsubstituted.

[0069] Examples of acyl groups represented by A1, A2, and A3 include formyl, acetyl, propionyl, butyryl, acryloyl, and hexanoyl. From the viewpoint of improving the biodegradation rate of resin particles, acyl groups with two or more but less than four carbon atoms are more preferred, and those with two or three carbon atoms are even more preferred.

[0070] Examples of cellulose acylates include cellulose acetate (cellulose monoacetate, cellulose diacetate (DAC), cellulose triacetate), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB).

[0071] From the viewpoint of improving the biodegradation rate of resin particles, cellulose acylates are preferably, for example, cellulose acylates having two or more acyl groups. Specifically, from the viewpoint of improving the biodegradation rate of resin particles, cellulose acetate, cellulose propionate (CAP), and cellulose acetate butyrate (CAB) are preferred as cellulose acylates, more preferably cellulose propionate (CAP), and even more preferably cellulose acetate butyrate (CAB).

[0072] Cellulose acylates with two or more acyl groups tend to have a high biodegradability rate. Therefore, by using cellulose acylates with two or more acyl groups, even resin particles with low alkali metal content on the particle surface can more easily maintain biodegradability.

[0073] Cellulose acetate has a particularly high tendency to biodegrade, so it is easier to improve biodegradability by using cellulose acetate.

[0074] Cellulose acylates can be used alone or in combination with two or more.

[0075] The weight-average degree of polymerization of the cellulose acylate is preferably 200 or more and 1000 or less, more preferably 500 or more and 1000 or less, and even more preferably 600 or more and 1000 or less.

[0076] The weight-average degree of polymerization of cellulose acylates is determined from the weight-average molecular weight (Mw) in the following order.

[0077] First, the weight-average molecular weight (Mw) of cellulose acylates was measured using tetrahydrofuran and by gel permeation chromatography (GPC apparatus: TOSOH CORPORATION, HLC-8320GPC, column: TSKgelα-M) to polystyrene conversion.

[0078] Next, the degree of polymerization of the cellulose acylate is determined by dividing by the molecular weight of the structural unit. For example, when the substituent of the cellulose acylate is acetyl, the molecular weight of the structural unit is 263 when the degree of substitution is 2.4, and 284 when the degree of substitution is 2.9.

[0079] From the viewpoint of improving the biodegradation rate of resin particles, the degree of substitution of cellulose acylate is preferably 2.1 or more and 2.9 or less, more preferably 2.2 or more and 2.9 or less, even more preferably 2.3 or more and 2.9 or less, and especially preferably 2.6 or more and 2.9 or less.

[0080] From the viewpoint of improving the biodegradation rate of resin particles, in cellulose acetate propionate (CAP), the ratio of the degree of substitution of acetyl groups to propionyl groups (acetyl / propionyl) is preferably 0.01 or more and 1 or less, more preferably 0.05 or more and 0.1 or less.

[0081] From the viewpoint of improving the biodegradation rate of resin particles, in cellulose acetate butyrate (CAB), the ratio of the degree of substitution of acetyl groups to butyryl groups (acetyl / butyryl) is preferably 0.05 or more and 3.5 or less, more preferably 0.5 or more and 3.0 or less.

[0082] The degree of substitution of cellulose acylates refers to the extent to which the hydroxyl groups of cellulose are replaced by acyl groups. In other words, the degree of substitution becomes an indicator of the degree of acylation of cellulose acylates. Specifically, the degree of substitution represents the intramolecular average number of substitutions in the D-pyranose units of cellulose acylates where three hydroxyl groups are replaced by acyl groups. The degree of substitution is determined by the integral ratio of the peak values ​​of hydrogen from cellulose to hydrogen from acyl groups using 1H-NMR (prepared by JMN-ECA / JEOL RESONANCE).

[0083] These biodegradable resins can be used alone or in combination.

[0084] The content of cellulose acylates relative to the total amount of parent particles is preferably 50% by mass or more. Cellulose acylates tend to have a high biodegradation rate. Therefore, by setting the content of cellulose acylates to the above range, even resin particles with low alkali metal content on the particle surface are more likely to maintain biodegradability.

[0085] -Plasticizer-

[0086] The parent material may contain plasticizers.

[0087] Examples of plasticizers include ester compounds, cashew nut compounds, camphor, metal soaps, polyols, and polyepoxides. From the viewpoint of improving the mechanical properties of resin particles, at least one of ester compounds and cashew nut compounds is preferred as a plasticizer. Furthermore, a single plasticizer or two or more plasticizers can be used in combination.

[0088] Examples of ester compounds include fatty acid esters (adipate esters, citrate esters, sebate esters, azelaate esters, phthalate esters, acetate esters), phosphate esters, condensed phosphate esters, ethylene glycol esters (e.g., ethylene glycol benzoate), and modified fatty acid esters (e.g., epoxidized fatty acid esters). Examples of the aforementioned esters include monoesters, diesters, triesters, and polyesters. Among these, dicarboxylic acid diesters (adipate diesters, sebate diesters, azelaate diesters, phthalate diesters, etc.) are preferred, for example.

[0089] As a plasticizer, adipate ester is preferred, for example. Adipate ester has high compatibility with cellulose acylates and disperses in a near-uniform manner with cellulose acylates, thereby further improving thermal fluidity compared to other plasticizers.

[0090] As an adipic acid ester, a mixture of the adipic acid ester with other ingredients can be used. Commercially available examples of such mixtures include Daifatty 101 manufactured by DAIHACHI CHEMICAL INDUSTRY CO.,LTD.

[0091] Examples of fatty acid esters, such as citrate, sebacic acid ester, azelaic acid ester, phthalate, and acetate, include esters of fatty acids and alcohols. Examples of alcohols include monohydric alcohols such as methanol, ethanol, propanol, butanol, and 2-ethylhexanol; and polyhydric alcohols such as glycerol, polyglycerol (diglycerol, etc.), pentaerythritol, ethylene glycol, diethylene glycol, propylene glycol, butanediol, trimethylolpropane, trimethylolethane, and sugar alcohols.

[0092] Ethylene glycol, as a component of ethylene glycol benzoate, can be exemplified by ethylene glycol, diethylene glycol, propylene glycol, etc.

[0093] Epoxidized fatty acid esters are ester compounds having a structure in which the carbon-carbon unsaturated bonds of an unsaturated fatty acid ester are epoxidized (i.e., oxadiol). Examples of epoxidized fatty acid esters include esters of fatty acids and alcohols in which some or all of the carbon-carbon unsaturated bonds in unsaturated fatty acids (e.g., oleic acid, palmitoleic acid, isoleic acid, linoleic acid, linolenic acid, nervonic acid, etc.) are epoxidized. Examples of alcohols include monohydric alcohols such as methanol, ethanol, propanol, butanol, and 2-ethylhexanol; and polyhydric alcohols such as glycerol, polyglycerols (diglycerol, etc.), pentaerythritol, ethylene glycol, diethylene glycol, propylene glycol, butanediol, trimethylolpropane, trimethylolethane, and sugar alcohols.

[0094] The molecular weight (or weight-average molecular weight) of the ester compound used as a plasticizer is preferably 200 or more and 2000 or less, more preferably 250 or more and 1500 or less, and even more preferably 280 or more and 1000 or less. Unless otherwise specified, the weight-average molecular weight of the ester compound is the value measured in accordance with the method for measuring the weight-average molecular weight of cellulose acylates.

[0095] Cashew phenol compounds are preferred as plasticizers, for example.

[0096] Cashew phenol compounds refer to components contained in natural compounds derived from cashew trees (e.g., compounds represented by the following structural formulas (b-1) to (b-4)) or derivatives of said components.

[0097] [Chemical Formula 2]

[0098]

[0099] Cashew phenol compounds can be mixtures of naturally derived compounds made from the cashew tree (hereinafter also referred to as "cashew tree-derived mixtures").

[0100] Cashew phenol compounds can also be derivatives derived from mixtures derived from the cashew tree. Examples of derivatives derived from mixtures derived from the cashew tree include the following mixtures or monomers.

[0101] • A mixture in which the proportions of each component in a blend derived from cashew trees have been adjusted.

[0102] • Monomers from which specific components were isolated from a mixture derived from cashew trees

[0103] • A mixture containing modified compounds derived from cashew trees.

[0104] • A mixture containing polymers that aggregate components derived from cashew trees.

[0105] • A mixture containing modified polymers that modify and polymerize components derived from cashew trees.

[0106] • A mixture containing a modified body that further modifies the components in the mixture with the adjusted composition ratio.

[0107] • A mixture containing polymers from which components in a mixture with adjusted composition ratios are further polymerized.

[0108] • A mixture comprising modified polymers that further modify and polymerize the components in the mixture with the adjusted composition ratio.

[0109] • Modified products obtained by further modifying the separated monomers

[0110] • Polymers obtained by further polymerization of the separated monomers

[0111] • Modified polymers obtained by further modifying and polymerizing the separated monomers.

[0112] Here, it is assumed that the monomer also contains polymers such as dimers and trimers.

[0113] From the viewpoint of improving the biodegradation rate of resin particles, cashew phenol compounds are preferably, for example, compounds represented by general formula (CDN1) and at least one compound selected from the group consisting of compounds polymerized from compounds represented by general formula (CDN1).

[0114] [Chemical Formula 3]

[0115]

[0116] In the general formula (CDN1), R 1 R represents an alkyl group that may have substituents or an unsaturated aliphatic group that has a double bond and may have substituents. 2 This indicates a hydroxyl group, a carboxyl group, an alkyl group that may have substituents, or an unsaturated aliphatic group that has a double bond and may have substituents. P2 represents an integer greater than or equal to 0 and less than 4. When P2 is 2 or more, there are multiple R groups. 2 They can be the same group or different groups.

[0117] In the general formula (CDN1), R 1 The alkyl group that may have substituents is preferably an alkyl group with 3 or more and 30 or less carbon atoms, more preferably an alkyl group with 5 or more and 25 or less carbon atoms, and even more preferably an alkyl group with 8 or more and 20 or less carbon atoms.

[0118] Examples of substituents include hydroxyl groups; substituents containing ether bonds such as epoxy and methoxy groups; and substituents containing ester bonds such as acetyl and propionyl groups.

[0119] Examples of alkyl groups that may have substituents include pentadecane-1-yl, heptane-1-yl, octane-1-yl, nonanane-1-yl, decane-1-yl, undecane-1-yl, dodecane-1-yl, tetradecane-1-yl, etc.

[0120] In the general formula (CDN1), R 1The unsaturated aliphatic group having double bonds and substituents is preferably an unsaturated aliphatic group with 3 or more and 30 or less carbon atoms, more preferably an unsaturated aliphatic group with 5 or more and 25 or less carbon atoms, and even more preferably an unsaturated aliphatic group with 8 or more and 20 or less carbon atoms.

[0121] The number of double bonds in the unsaturated aliphatic group is preferably one or more and three or less.

[0122] As substituents, examples of substituents that are substituents of the alkyl group can also be cited.

[0123] Examples of unsaturated aliphatic groups that have double bonds and may have substituents include pentadecane-8-en-1-yl, pentadecane-8,11-dien-1-yl, pentadecane-8,11,14-trien-1-yl, pentadecane-7-en-1-yl, pentadecane-7,10-dien-1-yl, and pentadecane-7,10,14-trien-1-yl.

[0124] In the general formula (CDN1), as R 1 For example, pentadecane-8-en-1-yl, pentadecane-8,11-dien-1-yl, pentadecane-8,11,14-trien-1-yl, pentadecane-7-en-1-yl, pentadecane-7,10-dien-1-yl, and pentadecane-7,10,14-trien-1-yl are preferred.

[0125] In the general formula (CDN1), as R 2 The alkyl groups that may have substituents and the unsaturated aliphatic groups that have double bonds and may have substituents, as represented by R, can also be exemplified by R. 1 Examples of preferred embodiments are alkyl groups that may have substituents and unsaturated aliphatic groups that have double bonds and may have substituents.

[0126] The compound represented by the general formula (CDN1) can be further modified. For example, it can be epoxidized. From the viewpoint of improving the biodegradation rate of resin particles, in particular, it is preferred, for example, to be a compound represented by the general formula (CDN1) in which the hydroxyl groups are replaced with the following group (EP), i.e., a compound represented by the following general formula (CDN1-e).

[0127] [Chemical Formula 4]

[0128]

[0129] In the group (EP) and general formula (CDN1-e), L EP Represents a single bond or a divalent linkage group. In the general formula (CDN1-e), R 1 R2 And P2 and R in general formula (CDN1) 1 R 2 P2 has the same meaning.

[0130] In the group (EP) and general formula (CDN1-e), as L EP Examples of divalent linking groups include alkylene groups that may have substituents (preferably alkylene groups with 1 or more but less than 4 carbon atoms, more preferably alkylene groups with 1 carbon atom), -CH2CH2OCH2CH2- groups, etc.

[0131] As a substituent mentioned above, another example can be found in R of the general formula (CDN1). 1 Substituents listed in the table are those that are used as substituents.

[0132] As L EP For example, methylene is preferred.

[0133] A polymer of compounds represented by general formula (CDN1) is a polymer of at least two compounds represented by general formula (CDN1) polymerized, with or without the use of linking groups.

[0134] As a polymer of a compound represented by the general formula (CDN1), for example, a compound represented by the general formula (CDN2) can be cited.

[0135] [Chemical Formula 5]

[0136]

[0137] In the general formula (CDN2), R 11 R 12 and R 13 Each can be independently represented as an alkyl group that may have substituents or an unsaturated aliphatic group that has a double bond and may have substituents. R 21 R 22 and R 23 Each group independently represents a hydroxyl group, a carboxyl group, an alkyl group that may have substituents, or an unsaturated aliphatic group that has a double bond and may have substituents. P21 and P23 independently represent integers greater than or equal to 0 and less than 3, and P22 represents an integer greater than or equal to 0 and less than 2. L 1 and L 2 Each of these groups independently represents a divalent linker. n represents an integer greater than 0 and less than 10. When P21 is greater than 2, there exist a complex number of R groups. 21 When P22 is 2 or more, there exist a complex number of R. 22 And when P23 is 2 or more, there exist multiple R's. 23 They can be the same or different. When n is 2 or more, there exist a complex number of R. 12R 22 and L 1 They can be the same group or different groups. When n is 2 or more, there are multiple P22s, which can be the same number or different numbers.

[0138] In the general formula (CDN2), as R 11 R 12 R 13 R 21 R 22 and R 23 The alkyl groups that may have substituents and the unsaturated aliphatic groups that have double bonds and may have substituents, as exemplified by R as a general formula (CDN1), are also mentioned. 1 The examples listed here are preferred examples.

[0139] In the general formula (CDN2), L is used as 1 and L 2 The divalent linking group represented can be, for example, an alkylene group that may have substituents (preferably an alkylene group with 2 or more and 30 or less carbon atoms, more preferably an alkylene group with 5 or more and 20 or less carbon atoms).

[0140] As a substituent mentioned above, another example can be found in R of the general formula (CDN1). 1 Substituents listed in the table are those that are used as substituents.

[0141] In the general formula (CDN2), n is preferably 1 or more and 10 or less, and more preferably 1 or more and 5 or less.

[0142] Compounds represented by the general formula (CDN2) can be further modified. For example, they can be epoxidized, specifically, compounds with the structure of having hydroxyl groups replaced by groups (EP) in compounds represented by the general formula (CDN2), i.e., compounds represented by the following general formula (CDN2-e).

[0143] [Chemical Formula 6]

[0144]

[0145] In the general formula (CDN2-e), R 11 R 12 R 13 R 21 R 22 R 23 P21, P22, P23, L 1 L 2 and n are respectively related to R in the general formula (CDN2) 11 R 12 R 13 R21 R 22 R 23 P21, P22, P23, L 1 L 2 The meanings of "and n" are the same.

[0146] In the general formula (CDN2-e), L EP1 L EP2 and L EP3 Each can independently represent a single bond or a divalent linker. When n is 2 or more, there are multiple L's. EP2 They can be the same group or different groups.

[0147] In the general formula (CDN2-e), L is used as EP1 L EP2 and L EP3 The divalent linker represented can also be exemplified as L in the general formula (CDN1-e). EP Examples of preferred embodiments are listed using the divalent linking groups represented.

[0148] The polymer, which is a polymer of a compound represented by the general formula (CDN1), may be, for example, a polymer in which at least three or more compounds represented by the general formula (CDN1) are three-dimensionally cross-linked, with or without the help of linking groups. Examples of polymers in which compounds represented by the general formula (CDN1) are three-dimensionally cross-linked, include compounds represented by the following structural formulas.

[0149] [Chemical Formula 7]

[0150]

[0151] In the above structural formula, R 10 R 20 And P20 and R in general formula (CDN1) 1 R 2 The meaning is the same as P2. L 10 Indicates a single bond or a divalent linkage group. Multiple R groups exist. 10 R 20 and L 10 These can be the same group or different groups. There can be a plurality of P20s, which can be the same number or different numbers.

[0152] In the above structural formula, as L 10 The divalent linking group represented can be, for example, an alkylene group that may have substituents (preferably an alkylene group with 2 or more and 30 or less carbon atoms, more preferably an alkylene group with 5 or more and 20 or less carbon atoms).

[0153] As a substituent mentioned above, another example can be found in R of the general formula (CDN1). 1 Substituents listed in the table are those that are used as substituents.

[0154] The compounds represented by the above structural formulas can be further modified, for example, by epoxidation. Specifically, it can be a compound in which the hydroxyl groups of the compound represented by the above structural formulas are replaced by groups (EP), such as a compound represented by the following structural formula, namely a polymer of a compound represented by the general formula (CDN1-e) through three-dimensional cross-linking polymerization.

[0155] [Chemical Formula 8]

[0156]

[0157] In the above structural formula, R 10 R 20 And P20 and R in the general formula (CDN1-e) 1 R 2 The meaning is the same as P2. L 10 Indicates a single bond or a divalent linkage group. Multiple R groups exist. 10 R 20 and L 10 These can be the same group or different groups. There can be a plurality of P20s, which can be the same number or different numbers.

[0158] In the above structural formula, as L 10 The divalent linking group represented can be, for example, an alkylene group that may have substituents (preferably an alkylene group with 2 or more and 30 or less carbon atoms, more preferably an alkylene group with 5 or more and 20 or less carbon atoms).

[0159] As a substituent mentioned above, another example can be found in R of the general formula (CDN1). 1 Substituents listed in the table are those that are used as substituents.

[0160] From the viewpoint of improving the transparency of the resin molded article, the cashew nut compound preferably includes, for example, a cashew nut compound having an epoxy group, and more preferably a cashew nut compound having an epoxy group.

[0161] Commercially available cashew nutshell compounds can be used. Examples of commercially available cashew nutshell compounds include NX-2024, Ultra LITE 2023, NX-2026, GX-2503, NC-510, LITE 2020, NX-9001, NX-9004, NX-9007, NX-9008, NX-9201, NX-9203 manufactured by Cardolite, and LB-7000, LB-7250, and CD-5L manufactured by TOHOKU CHEMICAL INDUSTRIES, LTD. Commercially available cashew nutshell compounds with epoxy groups include NC-513, NC-514S, NC-547, LITE513E, and Ultra LTE 513 manufactured by Cardolite.

[0162] From the viewpoint of improving the biodegradation rate of the resin molded article, the hydroxyl value of the cashew nut shell compound is preferably 100 mg KOH / g or more, more preferably 120 mg KOH / g or more, and even more preferably 150 mg KOH / g or more. The hydroxyl value of the cashew nut shell compound is measured according to Method A of ISO 14900.

[0163] When using a cashew nut compound with an epoxy group, from the viewpoint of improving the transparency of the resin molded article, its epoxy equivalent is preferably 300 or more and 500 or less, more preferably 350 or more and 480 or less, and even more preferably 400 or more and 470 or less. The epoxy equivalent of the cashew nut compound with an epoxy group is measured according to ISO 3001.

[0164] From the viewpoint of improving the biodegradation rate of the resin molded article, the molecular weight of the cashew phenol compound is preferably 250 or more and 1000 or less, more preferably 280 or more and 800 or less, and even more preferably 300 or more and 500 or less.

[0165] Cashew phenol compounds can be used alone or in combination with two or more.

[0166] The content of plasticizer relative to the total amount of resin particles is preferably 0% or more and 50% or less by mass, more preferably 5% or more and 40% or less by mass, and even more preferably 10% or more and 30% or less by mass.

[0167] -Other ingredients-

[0168] Other components may be contained in the parent particle.

[0169] Other components include, for example, plasticizers, flame retardants, compatibilizers, anti-sticking agents, lightfastness agents, weathering agents, colorants, pigments, modifiers, anti-drip agents, antistatic agents, hydrolysis inhibitors, fillers, reinforcing agents (glass fiber, carbon fiber, talc, clay, mica, glass flakes, cullet, glass beads, crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, etc.), acid-sensitive agents used to prevent the release of acetic acid (oxides such as magnesium oxide and aluminum oxide; metal hydroxides such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, and hydrotalcite; calcium carbonate; talc, etc.), and reactive scavenging agents (e.g., epoxy compounds, acid anhydride compounds, carbodiimide, etc.).

[0170] The content of other components relative to the total amount of parent particles is preferably 0% by mass or more and 5% by mass or less. Here, "0% by mass" means that no other components are included.

[0171] The parent material may contain resins other than biodegradable resins. However, when other resins are included, their content relative to the total amount of parent material should be, for example, less than 5% by mass, and preferably less than 1% by mass. More preferably, no other resins are contained (i.e., 0% by mass).

[0172] Other resins include, for example, conventionally known thermoplastic resins, specifically, polycarbonate resins; polypropylene resins; polyester resins; polyolefin resins; polyester carbonate resins; polyphenylene ether resins; polyphenylene sulfide resins; polysulfone resins; polyethersulfone resins; polyaryl resins; polyetherimide resins; polyacetal resins; polyvinyl alcohol acetal resins; polyketone resins; polyetherketone resins; polyetheretherketone resins; polyaryl ketone resins; polyether nitrile resins; liquid crystal resins; polybenzimidazole resins; polyurethane resins; and resins selected from aromatic olefins. Vinyl polymers or copolymers obtained by polymerization or copolymerization of one or more vinyl monomers from the group consisting of vinyl compounds, methacrylates, acrylates, and ethylene cyanide compounds; diene-aromatic alkenyl compound copolymers; ethylene cyanide-diene-aromatic alkenyl compound copolymers; aromatic alkenyl compound-diene-ethylene cyanide-N-phenylmaleimide copolymers; ethylene cyanide-(ethylene-diene-propylene (EPDM))-aromatic alkenyl compound copolymers; vinyl chloride resins; vinyl chloride resins, etc. These resins can be used alone or in combination of two or more.

[0173] (Floor 1 and Floor 2)

[0174] The resin particles involved in this embodiment preferably have, for example, a first layer comprising at least one cationic resin selected from polyalkyleneimide, polyacrylamide, and polyethyleneamine, and a second layer comprising anionic or nonionic hydrophobic compounds on the surface of the parent particle.

[0175] By having the first and second layers, the atomic weight A of alkali metals on the surface of the resin particles is more easily reduced. Therefore, shelf life in aqueous solutions is further improved.

[0176] -Level 1-

[0177] The first layer is a resin layer present on the surface of the parent particle. Furthermore, the first layer comprises at least one cationic resin selected from polyalkyleneimide, polyacrylamide, and polyethyleneimine.

[0178] The cationic resin can be any of polyalkylene imide, polyacrylamide, and polyethyleneimine, but from the viewpoint of increasing biodegradation rate over time and decreasing initial biodegradation rate, polyalkylene imide is preferred, for example.

[0179] From the viewpoint of increasing biodegradation rate over time and decreasing initial biodegradation rate, polyalkylene imides are preferred, for example, those having structural units having alkylene groups having 1 or more and 6 or less carbon atoms (preferably 1 or more and 4 or less carbon atoms, more preferably 1 or more and 2 or less carbon atoms), and polyethyleneimine is even more preferred.

[0180] Polyethyleneimine, in particular, is a compound with high adhesiveness and high water absorption. This is because the amino and hydroxyl groups of polyethyleneimine are hydrogen-bonded, ion-bonded with carboxyl groups, and covalently bonded with carbonyl groups. Furthermore, polyethyleneimine possesses both polar groups (amino) and hydrophobic groups (vinyl) in its structure, thus exhibiting the property of readily bonding with different substances.

[0181] Furthermore, polyethyleneimine is a highly cationic compound. Therefore, polyethyleneimine exists in water in a polycationic form and neutralizes and adsorbs anionic substances.

[0182] Furthermore, polyethyleneimine possesses highly reactive primary or secondary amine groups, making it a highly reactive compound. Consequently, it readily reacts with a wide variety of compounds.

[0183] Therefore, as a polyalkylene imide, if polyethyleneimine is used, the second layer containing the aqueous compound is more firmly coated by the parent particle, thus having a biodegradation rate that varies over time, and the initial biodegradation rate tends to slow down.

[0184] From the viewpoint that the rate of biodegradation increases over time and the initial rate of biodegradation decreases, the number average molecular weight of the cationic resin is preferably 300 or more and 100,000 or less, more preferably 10,000 or more and 85,000 or less, and even more preferably 50,000 or more and 80,000 or less.

[0185] The number-average molecular weight of the cationic resin was measured using tetrahydrofuran and converted to polystyrene by gel permeation chromatography (GPC apparatus: TOSOH CORPORATION, HLC-8320GPC, column: TSKgelα-M).

[0186] -Level 2-

[0187] The second layer is a compound layer present on top of the first layer. Furthermore, the second layer contains anionic or nonionic compounds or hydrophobic compounds.

[0188] Examples of anionic or nonionic compounds or hydrophobic compounds include hydrophobic compounds with anionic groups (-COOH (carboxyl group), -SO3H (sulfone group), etc.) and hydrophobic compounds without cationic or anionic groups.

[0189] Furthermore, the term "water-degradable compound" refers to a compound that imparts water degradability (specifically, water contact angle) to the biodegradable resin particles described later.

[0190] Examples of aqueous compounds include silicone compounds, hydrocarbon compounds, fatty acid compounds, acrylic resins, polyester resins, and urethane resins.

[0191] From the viewpoint of increasing biodegradation rate over time and decreasing initial biodegradation rate, it is preferably selected from at least one of the group consisting of silicone compounds, hydrocarbon compounds, fatty acid compounds, acrylic resins, polyester resins and urethane resins.

[0192] Examples of silicone compounds include dimethyl polysiloxane, methyl polysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, cyclopolymethylsiloxane, various modified silicone oils (alkyl-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, fluorine-modified silicone oil, amino-modified silicone oil, etc.), MQ resin, and silicone rubber.

[0193] Among them, from the viewpoint of increasing biodegradation rate over time and decreasing initial biodegradation rate, the silicone compound is preferably selected from at least one of the group consisting of dimethyl polysiloxane, methyl polysiloxane, MQ resin and silicone rubber.

[0194] Here, MQ resin refers to a silicone resin having a monofunctional siloxane unit [(CH3)3SiO1 / 2], i.e., the M unit, and a tetrafunctional siloxane unit [SiO4 / 2], i.e., the Q unit.

[0195] Commercially available silicone compounds include those manufactured by Shin-Etsu Chemical Co., Ltd. (KM-902, KM-903, KM-910, KM-9729, POLON-MN-ST, KM-9737A, KM-9782, KM-9738A, KM-752T, POLON-MF-33, KM-9717, X-51-1302M (MQ resin), POLON-MF-56, KM-2002-L-1, KM-2002-T, KM-9772, KM-9749, POLON-MF-40, KM-9729, X-52-1133, etc.) and those manufactured by Wacker Asahikasei SiliconeCo., Ltd. (BELSIL DM3112VP).

[0196] Examples of hydrocarbon compounds include petroleum waxes (paraffin wax, microcrystalline wax, petrolatum wax, etc.) and synthetic hydrocarbon waxes (polyethylene wax, polypropylene wax, polybutene wax, Fischer-Tropsch synthetic wax, etc.).

[0197] From the viewpoint of increasing biodegradation rate over time and decreasing initial biodegradation rate, the hydrocarbon compound is preferably selected from at least one of the group consisting of paraffin wax, microcrystalline wax, polyethylene wax, and polypropylene wax.

[0198] Commercially available hydrocarbon compounds include microcrystalline wax (EMUSTAR-0001, etc.) manufactured by NIPPON SEIRO CO.,LTD., paraffin wax (EMUSTAR-0135, etc.) manufactured by NIPPON SEIRO CO.,LTD., paraffin wax (AQUACER497, etc.) manufactured by BYK, polyethylene wax (AQUACER507, AQUACER840, AQUACER1547, AQUACER272, etc.) manufactured by BYK, polyethylene wax (HITEC E-2213, HITEC E-6324, etc.) manufactured by TOHO Chemical Industry Co.,Ltd., polypropylene wax (AQUACER593, etc.) manufactured by BYK, and polypropylene (HITEC P-9018, HITEC P-5060P, etc.) manufactured by TOHO Chemical Industry Co.,Ltd.

[0199] Examples of fatty acid compounds include vegetable oils containing fatty acids (castor oil, tung oil, linseed oil, shortening, corn oil, soybean oil, sesame oil, rapeseed oil, sunflower oil, rice bran oil, camellia oil, coconut oil, palm oil, walnut oil, olive oil, peanut oil, almond oil, jojoba oil, cocoa butter, shea butter, neem oil, safflower oil, wood wax, candelilla wax, rice bran wax, carnauba wax, etc.).

[0200] From the viewpoint of increasing biodegradation rate over time and decreasing initial biodegradation rate, it is preferably selected from at least one of the group consisting of carnauba wax, rice bran wax, candelilla wax, palm wax, castor oil wax, soybean oil wax and sunflower oil wax.

[0201] Commercially available fatty acid compounds include canopy wax (EMUSTAR-0413 (Brazilian carnauba wax)) manufactured by NIPPON SEIRO CO.,LTD., rice bran wax (AQUASPROUT-7300, etc.) manufactured by NIPPON SEIRO CO.,LTD., palm wax (AQUASPROUT-7100, etc.) manufactured by NIPPON SEIRO CO.,LTD., castor oil wax (AQUASPROUT-7500, etc.) manufactured by NIPPON SEIRO CO.,LTD., soybean oil wax (AQUASPROUT-7200, etc.) manufactured by NIPPON SEIRO CO.,LTD., sunflower oil wax (AQUASPROUT-7400, etc.) manufactured by NIPPON SEIRO CO.,LTD., and palm oil wax (kakkokasei TKE, etc.) manufactured by NIPPON SEIRO CO.,LTD., etc.

[0202] Examples of acrylic resins include polymers of acrylic acid and polymers of alkyl acrylates.

[0203] Commercially available acrylic resins include, for example, those manufactured by TAISEI FINE CHEMICAL CO,.LTD. (3WX-2015, 3MF-320, 3MF-333, 3MF-407, etc.) and those manufactured by DIC CORPORATION (KOTE SFC-6440, BONKOTE CE-6270, BONKOTE CE-6400, BONKOTE CF-2800, etc.).

[0204] Examples of polyester resins include condensation polymers of polycarboxylic acids and polyols, and ring-opening condensation polymers of cyclic lactams.

[0205] Commercially available polyester resins include, for example, polyester resins manufactured by Takamatsu Oil & Fat Co., Ltd. (A-110F, A-160P, A-520, A-613D, A-615GE, A-640, A-645GH, A-647GEX, etc.).

[0206] Examples of urethane resins include polyester polyurethanes, polyether polyurethanes, and polycarbonate polyurethanes. Furthermore, materials in which a urethane polymer shell surrounds the core of a propylene polymer fiber can also be used as urethane resins.

[0207] Commercially available urethane resins include, for example, those manufactured by TAISEI FINE CHEMICAL CO,.LTD. (WEM-031U, WEM-200U, WEM-321U, WEM-3000, WBR-016U, WBR-2101, etc.).

[0208] -Content of each layer-

[0209] In the biodegradable resin particles involved in this embodiment, from the viewpoint of increasing biodegradation rate over time and decreasing initial biodegradation rate, the mass ratio of the amount of cationic resin coating in the first layer to the amount of aqueous compound coating in the second layer (the amount of cationic resin coating / the amount of aqueous compound coating) is preferably 0.05 or more and 20 or less, more preferably 0.1 or more and 10 or less, and even more preferably 0.1 or more and 3 or less.

[0210] Furthermore, the content of cationic resin relative to the master particles (based on the coating amount of the first layer relative to the total amount of master particles) is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, and even more preferably 0.1% by mass or more and 3% by mass or less.

[0211] By setting the content of cationic resin relative to the parent particles within the aforementioned range, the atomic weight A of alkali metals on the surface of the resin particles is further reduced. Therefore, the shelf life in aqueous solutions is further improved.

[0212] Furthermore, from the viewpoint of further improving the storeability in aqueous solutions, the content of the aqueous compound relative to the parent particles (based on the amount of the second layer coating relative to the total amount of the parent particles) is preferably, for example, 0.05% by mass or more and 15% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, and even more preferably 0.1% by mass or more and 3% by mass or less.

[0213] Here, the coating amounts of the cationic resin and the aqueous compound (i.e., the coating amounts of the first and second layers) are measured as follows. The coating amount of the cationic resin is determined by the difference between the amount of cationic resin processed and the amount of cationic resin obtained by drying and curing the treated supernatant. Similarly, the coating amount of the aqueous compound is determined by the difference between the amount of aqueous compound processed and the amount of aqueous compound obtained by drying and curing the treated supernatant.

[0214] <Properties of Resin Particles>

[0215] (particle size)

[0216] The volume average particle size of the biodegradable resin particles is preferably 3 μm or more and 100 μm or less, more preferably 5 μm or more and 70 μm or less, and even more preferably 8 μm or more and 60 μm or less.

[0217] If the particle size of the granules is set to 3 μm or larger, the number of particles per unit weight will not become excessive, thus suppressing the decrease in biodegradation rate. On the other hand, if the particle size of the biodegradable resin particles is set to 100 μm or smaller, the specific surface area increases, which can further improve the biodegradation rate.

[0218] Therefore, the volume average particle size of the granules is preferably within the range described above.

[0219] The particle size distribution index GSDv of the large diameter side number of biodegradable resin particles is preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.2 or less.

[0220] If the particle size distribution of biodegradable resin particles is made nearly uniform, it provides them with a certain opportunity to come into contact with water, thereby enabling regular hydrolysis and further increasing the rate of biodegradation.

[0221] The volume average particle size and large diameter side particle size distribution index GSDp of biodegradable resin particles were measured as follows.

[0222] The particle size was measured using the Beckman Coulter LS13 320 (BECKMAN COULTER) particle size distribution measurement device. The cumulative distribution of the particle size was plotted from the small diameter side with a volume reference, and the particle size that constituted the cumulative 50% was determined as the volume average particle size.

[0223] On the other hand, describing the cumulative distribution of particle size on the small-diameter side using a volumetric criterion, the particle size that accounts for the cumulative 50% is defined as the number average particle size D50v, and the particle size that accounts for the cumulative 84% is defined as the number particle size D84v. Furthermore, the number particle size distribution index GSDv on the large-diameter side is given by the formula GSDv = (D84v / D50v).1 / 2 calculate.

[0224] (Atomic weight A and atomic weight B)

[0225] The alkali metal atomic weight A on the surface of resin particles, measured by X-ray photoelectron spectroscopy relative to the total atomic weight present on the surface of resin particles, and the alkali metal atomic weight B on the surface of resin particles, measured by X-ray fluorescence spectroscopy relative to the total atomic weight present on the surface of resin particles, satisfy the relationship that 0 ≤ (A / B) < 0.15 and 0.005atomic% ≤ B ≤ 0.5atomic%.

[0226] From the viewpoint of further improving the storeability in aqueous solutions, the atomic weights A and B preferably satisfy, for example, 0 ≤ (A / B) ≤ 0.12, more preferably 0 ≤ (A / B) ≤ 0.10, and even more preferably 0 ≤ (A / B) ≤ 0.07.

[0227] Furthermore, from the viewpoint of improving biodegradability, the atomic weight B preferably satisfies, for example, 0.05 atomic% ≤ B ≤ 0.40 atomic, more preferably 0.10 atomic% ≤ B ≤ 0.35 atomic, and even more preferably 0.15 atomic% ≤ B ≤ 0.30 atomic.

[0228] As an alkali metal, Na is preferred.

[0229] Here, the atomic mass of Na present on the surface of the resin particles is A, relative to the total atomic mass present on the surface of the resin particles. Na and the atomic weight of Na in the resin particles, as measured by X-ray fluorescence spectroscopy, relative to the total atomic weight present in the resin particles. Na For example, it is preferable to satisfy 0≤(A) Na / B Na ) < 0.15 and 0.005atomic% ≤ B Na The relationship is ≤0.5 atomic%.

[0230] The biodegradability of resins is improved by the presence of Na in alkali metals, which tend to have a higher Na content. Therefore, the presence of Na in alkali metals further enhances the biodegradability of resin particles. Furthermore, the atomic weight of Na... Na and atomic weight B Na Satisfying the above relationship increases the proportion of Na, an alkali metal, in the resin particles, thereby further improving the biodegradability of the resin particles.

[0231] The atomic weight A is calculated as follows.

[0232] The X-ray photoelectron spectroscopy apparatus used was a "ULVAC-PHI, Inc. PHI5000 Versa Probe II". The X-ray source used a monochromatic AlKα spectral line, and the accelerating voltage was set to 15 kV for measurement. The sample tilt angle was adjusted, and the incident angle θ was set to 15°. Only the outermost surface of the particles was measured. Based on the measured spectra of each atom, the number of each atom was determined, and the alkali metal atomic weight relative to the total atomic weight in the measurement area was calculated. Furthermore, the alkali metal atomic weight A (atomic%) is the percentage of the total number of detected alkali metal atoms relative to the total detected atomic weight.

[0233] The atomic weight B is calculated as follows.

[0234] Using an X-ray fluorescence analyzer (Shimadzu Corporation, XRF1500), with X-ray output at 40V and 70mA, the area was measured. Qualitative and quantitative analyses were performed under a 15-minute measurement period. Here, all elements in the measurement area were analyzed. Based on the measured spectra of each atom and referring to separately prepared calibration curves capable of quantifying each element, the atomic weight of each element was calculated, and the alkali metal atomic weight relative to the total atomic weight in the measurement area was also calculated. Furthermore, the alkali metal atomic weight B (atomic%) is the percentage of the total number of detected alkali metal atoms relative to the total number of detected atoms.

[0235] (The relationship between [AL1], [AL2] and [AL3])

[0236] The following definitions apply to [AL1], [AL2], and [AL3].

[0237] • [AL1]: The amount of alkali metal atoms on the surface of resin particles as measured by X-ray photoelectron spectroscopy.

[0238] ·[AL2]: Alkali metal atomic mass on the surface of resin particles after etching a 2 mm square area on the surface of the resin particles for 5 minutes using an argon cluster ion gun with an output of 5 kV.

[0239] ·[AL3]: Alkali metal atomic mass on the surface of resin particles after etching a 2 mm square area on the surface of the resin particles for 30 minutes using an argon cluster ion gun with an output of 5 kV.

[0240] Furthermore, the resin particles involved in this embodiment satisfy the relationship [AL1]<[AL3]<[AL2].

[0241] From the viewpoint of being resin particles that are more biodegradable and have better storage properties in aqueous solutions, [AL1], [AL2] and [AL3] are preferably configured as follows, for example.

[0242] [AL1] Preferably, the content is 0% or more and 0.08% or less, more preferably 0% or more and 0.06% or less, and even more preferably 0% or more and 0.03% or less.

[0243] [AL2] Preferably, it is 0.1 atomic% or more and 10 atomic% or less, more preferably 0.2 atomic% or more and 9 atomic% or less, and even more preferably 0.3 atomic% or more and 8 atomic% or less.

[0244] [AL3] Preferably, it is 0.09 atomic% or more and 4 atomic% or less, more preferably 0.09 atomic% or more and 3 atomic% or less, and even more preferably 0.09 atomic% or more and 2 atomic% or less.

[0245] From the viewpoint of being resin particles that are more biodegradable and have better storage properties in aqueous solutions, [AL1], [AL2] and [AL3] are, for example, further preferably satisfying the following relationship.

[0246] The absolute value of the difference between [AL1] and [AL3] (|[AL1]-[AL3]|) is preferably 0.01 or more and 4 or less, more preferably 0.01 or more and 3 or less, and even more preferably 0.01 or more and 2 or less.

[0247] The absolute value of the difference between [AL3] and [AL2] (|[AL3]-[AL2]|) is preferably 0.01 or more and 9.91 or less, more preferably 0.01 or more and 8.91 or less, and even more preferably 0.01 or more and 7.91 or less.

[0248] The atomic weights of alkali metals are measured by XPS (X-ray photoelectron spectroscopy).

[0249] The order of measurement for the atomic weights of alkali metals [AL1], [AL2], and [AL3] is the same as the order of measurement for atomic weight A.

[0250] Specifically, [AL1] was measured in the same order as atomic weight A (i.e., [AL1] is the same as atomic weight A). Furthermore, the alkali metal atomic weight [AL2] was measured under the same XPS measurement conditions as atomic weight A on the surface of a 2 mm square area of ​​the resin particles after etching for 5 minutes using an argon cluster ion gun with an output of 5 kV. Moreover, the alkali metal atomic weight [AL3] was measured under the same XPS measurement conditions as atomic weight A on the surface of a 2 mm square area of ​​the resin particles after etching for 30 minutes using an argon cluster ion gun with an output of 5 kV.

[0251] Furthermore, the etching method for the surface of resin particles is described.

[0252] Specifically, an argon cluster ion gun with an output of 5kV was used to etch a 2mm square area on the outermost surface of the resin particles.

[0253] -Etching Conditions-

[0254] Etching gun: Argon cluster ion gun

[0255] Accelerating voltage: 5kV

[0256] Scanning area: 2mm × 2mm

[0257] Speed: 20 nm / min (converted to polyester)

[0258] <Method for manufacturing resin particles>

[0259] Examples of methods for manufacturing resin particles include the following.

[0260] (1) Mixing and crushing the components, crushing the resulting mixture and classifying it to obtain granular material;

[0261] (2) A dry method of obtaining granules by changing the shape of granules obtained by mixing and pulverizing through mechanical impact or heat.

[0262] (3) Mix the particle dispersion of each component, so that the particles in the dispersion aggregate and are heated and fused together to obtain the particle aggregation and fusion method.

[0263] (4) The organic solvent in which each component is dissolved is suspended in an aqueous solvent to produce granules containing each component by dissolution and suspension method.

[0264] (5) The components and binder are mixed and extruded to form granules. The granules are obtained by stirring in a solvent that dissolves only the binder. This is a mixing and dissolving method for granulation.

[0265] As a method for manufacturing resin particles, from the viewpoint that the atomic weights A and B satisfy the relationship 0 ≤ (A / B) < 0.15 and 0.005 atomic% ≤ B ≤ 0.5 atomic%, it is preferable to manufacture them by the method described above (4).

[0266] In the manufacture of resin particles based on the above (4) method, it is preferred to have the following steps: after suspending an organic solvent in which each component is dissolved in an aqueous solvent, an alkali metal element source is added to the suspension solution, for example, at a temperature range of 60°C or higher and 90°C or lower, for example, after stirring for 2 hours or more and 5 hours or less, the solvent is removed, thereby obtaining coarse particles (hereinafter also referred to as step A).

[0267] Furthermore, for example, it is preferable to have a step that involves adding dilute acid to the coarse particles after step A and then filtering them (hereinafter also referred to as step B).

[0268] Furthermore, for example, it is preferable to have the following steps: after step B, a step of dispersing the coarse particles obtained in step B into water and filtering the dispersion is performed (hereinafter also referred to as step C).

[0269] -Process A-

[0270] As a source of alkali metal elements added to the suspension, a hydroxide containing alkali metal elements is preferred, for example.

[0271] Examples of hydroxides containing alkali metal elements include lithium hydroxide, sodium hydroxide, potassium hydroxide, and rubidium hydroxide.

[0272] The amount of alkali metal element source added relative to the total amount of solid components contained in the suspension solution is preferably 2% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 10% by mass or less.

[0273] Here, as a method for adding an alkali metal element source to a suspension, a preferred method is, for example, to add an aqueous solution containing an alkali metal element source to the suspension.

[0274] -Process B-

[0275] The dilute acid added to the coarse particles obtained in step A is preferably, for example, dilute hydrochloric acid. The concentration of hydrogen chloride relative to the total amount of dilute hydrochloric acid is preferably, for example, 9% by mass or more and 11% by mass or less.

[0276] The amount of dilute acid added relative to 100 parts by mass of coarse particles obtained in step A is preferably 100 parts by mass or more and 3,000 parts by mass or less, more preferably 200 parts by mass or more and 1,000 parts by mass or less, and even more preferably 400 parts by mass or more and 800 parts by mass or less.

[0277] In step B, there are no particular limitations on the method used to filter the dispersion containing coarse particles and dilute acid; any known filtration method can be used. The same applies to the filtration method applicable in step C.

[0278] -Process C-

[0279] The amount of water used to disperse the coarse particles obtained in step B is preferably 100 parts by mass or more and 3,000 parts by mass or less, more preferably 200 parts by mass or more and 1,000 parts by mass or less, and even more preferably 400 parts by mass or more and 800 parts by mass or less, relative to 100 parts by mass of coarse particles obtained in step B.

[0280] In step C, for example, it is preferable to perform a series of steps, consisting of dispersing the coarse particles obtained in step B into water and filtering the dispersion, multiple times under the same conditions. When this series of steps is performed multiple times, the number of times is preferably more than two and less than four.

[0281] After step C, resin particles are obtained by drying the filtered residue.

[0282] Methods for manufacturing resin particles having the first layer and the second layer can be exemplified by the following methods.

[0283] -Step 1-

[0284] In the first step, the mother particle is prepared.

[0285] The manufacturing methods of the parent particles can be exemplified by the manufacturing methods of the resin particles (1) to (5).

[0286] Next, an aqueous dispersion of the obtained parent particles is prepared. Before preparing the aqueous dispersion, it is preferable to acid wash the parent particles, for example.

[0287] Next, an aqueous dispersion and an aqueous solution containing the dispersed parent particles and a cationic resin are mixed. Thereby, for example, the hydroxyl groups of the resin contained in the parent particles react with the amine sites of the cationic resin to form a first layer.

[0288] -Step 2-

[0289] In the second step, the masterbatch particles with the first layer formed are removed from the mixture. The removal of the masterbatch particles is carried out, for example, by filtering the mixture. The removed masterbatch particles are preferably washed with water, for example. This removes unreacted cationic resin.

[0290] Next, after preparing an aqueous dispersion containing the parent particles, the aqueous dispersion is mixed with a latex solution of anionic or nonionic aqueous compound. Thus, the latex of the aqueous compound is adsorbed onto the first layer of the parent particles.

[0291] Then, if the mixture is dried, the latex of the aqueous compound is destroyed, and the aqueous compound is film-formed on the first layer. Thus, the second layer is formed.

[0292] Through the above processes, the resin particles involved in this embodiment are obtained.

[0293] <Uses>

[0294] Examples of uses for the resin particles involved in this embodiment include cosmetic substrates, rolling materials, abrasives, washing agents, display pads, bead forming materials, light diffusing particles, resin reinforcing agents, refractive index control agents, biodegradation promoters, fertilizers, water-absorbing particles, toner particles, and granular particles that prevent adhesion.

[0295] Example

[0296] The following describes embodiments, but the present invention is not limited to these embodiments in any way. Furthermore, unless otherwise specified, "parts" and "%" in the following description refer to mass.

[0297] <Preparation of materials>

[0298] The following materials have been prepared.

[0299] [Biodegradable resins]

[0300] •CAB1: Eastman Chemical "CAB381-20", cellulose acetate butyrate, weight average degree of polymerization 890, degree of acetyl substitution 1.05, degree of butyryl substitution 1.74.

[0301] •CAB2: Eastman Chemical "CAB171-15", cellulose acetate butyrate, weight average degree of polymerization 754, degree of acetyl substitution 2.07, degree of butyryl substitution 0.73.

[0302] •CAP: Eastman Chemical "CAP482-20", cellulose acetate propionate, weight average degree of polymerization 716, degree of acetyl substitution 0.18, degree of propionyl substitution 2.49.

[0303] PA12: DAIAMID, Polyamide 12.

[0304] PA11: Arkema "Rilsan", polyamide 11.

[0305] •PBS: BioPBS, manufactured by Mitsubishi Chemical Corporation, is polybutylene succinate.

[0306] •DAC: Daicel Corporation. "L-50", cellulose diacetate, weight average degree of polymerization 570.

[0307] [Plasticizer]

[0308] ·DBA: Kao Corporation "Vinizer40", diisobutyl adipate

[0309] CDN: Cardolite "NX-2026", cashew phenol, molecular weight = 298-305

[0310] •ATBC: Citroflex A4, manufactured by MORIMURA BROS., INC., is a tributyl acetyl citrate.

[0311] • DPS: NIKKOL GROUP "NIKKOL DIS", diisopropyl sebacate

[0312] [Catonic resin in layer 1]

[0313] The number-average molecular weights of each cationic resin are listed in the table.

[0314] ·PEI1: Polyethyleneimine

[0315] ·PEI2: Polyethyleneimine

[0316] ·PEI3: Polyethyleneimine

[0317] • PAA: "PAA-25" manufactured by NITTOBO MEDICAL CO.,LTD., is polyacrylamide.

[0318] • PBAM: "PVAM-0595B" manufactured by Mitsubishi Chemical Corporation, polyvinylamine

[0319] [Anionic or cationic hydrophilic compounds in the second layer]

[0320] ·EMUSTAR-0413: Canopa wax manufactured by NIPPON SEIRO CO.,LTD.

[0321] • POLON-MN-ST: Dimethyl silicone manufactured by Shin-Etsu Chemical Co., Ltd.

[0322] KM-9717: MQ resin manufactured by Shin-Etsu Chemical Co., Ltd.

[0323] ·BELSIL DM3112VP: Polydimethylsiloxane manufactured by Wacker Asahikasei Silicone Co., Ltd.

[0324] HITEC E-2213: Polyethylene wax manufactured by TOHO Chemical Industry Co., Ltd.

[0325] HITEC P-9018: Polypropylene wax manufactured by TOHO Chemical Industry Co., Ltd.

[0326] 3MF-320: Acrylic resin manufactured by TAISEI FINE CHEMICAL CO,.LTD.

[0327] A-647GEX: Polyester resin manufactured by Takamatsu Oil & Fat Co., Ltd.

[0328] WBR-016U: A urethane resin manufactured by TAISEI FINE CHEMICAL CO,.LTD.

[0329] [Examples 1-11, 15-33, 34-36, 38-41, Comparative Examples 1, 2, 6-8]

[0330] (The creation of the mother particle)

[0331] The total amount of biodegradable resin and plasticizer shown in Table 1 (200g) was completely dissolved in 800g of methyl ethyl ketone according to the composition ratio shown in Table 1. This was then added to an aqueous solution containing 2g of calcium carbonate, 2g of carboxymethyl cellulose, and 200g of methyl ethyl ketone in 600g of distilled water, and stirred at 8000rpm for 5 minutes in a high-speed emulsifier (IKA). 200g of 1mol / L sodium hydroxide was added, and the mixture was heated to 80°C and stirred for 3 hours to remove the methyl ethyl ketone.

[0332] Next, 10% dilute hydrochloric acid, as shown in Table 1, was added to dissolve the calcium carbonate. Then, filtration was performed to recover the solid components.

[0333] Furthermore, the recovered solid components were dispersed in the amounts of pure water shown in Table 1, and a series of filtrations were performed in the order shown in Table 1 to obtain the mother particle slurry.

[0334] (Production of resin particles)

[0335] 500 parts of a slurry with a 20% solids content were prepared. For the solids content (100 parts) of this slurry, the cationic resin solution was added in the amounts shown in Table 1 (converted to purity), and the mixture was stirred at 25°C for 1 hour. After stirring, the residue was filtered, redispersed in pure water, and 500 parts of a slurry with a 20% solids content were prepared. For the solids content (100 parts) of this slurry, the aqueous compound was added in the amounts shown in Table 1 (converted to purity), and the mixture was stirred at 25°C for 1 hour. After stirring, the residue was filtered, and the solids were freeze-dried to obtain biodegradable resin particles.

[0336] Through the above processes, biodegradable resin particles were obtained.

[0337] [Example 12]

[0338] The 200g of 1mol / L sodium hydroxide added during the preparation of the master particles was replaced with 120g of 1mol / L lithium hydroxide. Otherwise, resin particles were obtained in the same manner as in Example 1.

[0339] [Example 13]

[0340] The 200g of 1mol / L sodium hydroxide added during the preparation of the master particles was replaced with 280g of 1mol / L potassium hydroxide. Otherwise, resin particles were obtained in the same manner as in Example 1.

[0341] [Example 14]

[0342] The 200g of 1mol / L sodium hydroxide added during the preparation of the masterbatch was replaced with 515g of 1mol / L rubidium hydroxide. Otherwise, the masterbatch slurry was obtained in the same manner as in Example 1.

[0343] [Example 37, Comparative Examples 3-5]

[0344] (Production of resin particles)

[0345] The total amount of biodegradable resin and plasticizer shown in Table 1 (200g) was completely dissolved in 800g of methyl ethyl ketone according to the composition ratio shown in Table 1. This was then added to an aqueous solution containing 2g of calcium carbonate, 2g of carboxymethyl cellulose, and 200g of methyl ethyl ketone in 600g of distilled water, and stirred at 8000rpm for 5 minutes in a high-speed emulsifier (IKA). 200g of 1mol / L sodium hydroxide was added, and the mixture was heated to 80°C and stirred for 3 hours to remove the methyl ethyl ketone.

[0346] Next, 10% dilute hydrochloric acid, as shown in Table 1, was added to dissolve the calcium carbonate. Then, filtration was performed to recover the solid components.

[0347] Furthermore, the recovered solid components were dispersed in the amount of pure water shown in Table 1, and a series of filtrations were performed in the order shown in Table 1. The solid components were then freeze-dried to obtain resin particles.

[0348] <Evaluation>

[0349] (Measurement of atomic weight and particle size)

[0350] The atomic weights A, B, [AL1], [AL2], [AL3], and number-average particle size D50v of the obtained resin particles were measured according to the described method.

[0351] (Shelf life evaluation: Measurement of mass loss rate in distilled water)

[0352] Five g of the obtained resin particles were sealed in a bag made of nylon mesh with a pore size of 1 μm (manufactured by AS ONE Corporation, nylon mesh #508 / 585-1 μm) and placed in pure water at 70°C for 14 days. The mass of the nylon mesh containing the resin particles was measured before and after the storage period, and the mass reduction rate was calculated. The shelf life was evaluated according to the following evaluation criteria.

[0353] A(◎): Weight reduction is less than 5%

[0354] B(〇): The reduction in quality is more than 5% but less than 10%.

[0355] C(△): The reduction in mass is more than 10% but less than 30%.

[0356] D(×): Mass reduction of 30% or more

[0357] (Biodegradability assessment: Measurement of mass reduction rate in compost)

[0358] Five g of the obtained resin particles were sealed in a bag made of nylon mesh with a pore size of 1 μm (manufactured by AS ONE Corporation, nylon mesh #508 / 585-1 μm) and buried in compost (manufactured by IRIS OHYAMA INC., compost bed). The compost contained more than 2% and less than 4% by mass in total, of which more than 1% and less than 3% by mass in total nitrogen, more than 0.1% and less than 1% by mass in total phosphate, and a carbon-nitrogen ratio (C / N ratio) of more than 20 and less than 30. The bag was placed in an oven set at 55°C for 14 days. The mass of the nylon mesh containing the resin particles was measured before and after the placement, and the mass reduction rate was calculated. The shelf life was evaluated according to the following evaluation criteria.

[0359] A(◎): The reduction in quality is over 95%.

[0360] B(〇): The reduction in quality is more than 90% but less than 95%.

[0361] C(△): Mass reduction exceeding 70% but less than 90%

[0362] D(×): The reduction in quality is less than 70%.

[0363]

[0364]

[0365]

[0366]

[0367] As can be seen from the above results, the resin particles in this embodiment are biodegradable resin particles with excellent storage properties in aqueous solutions.

[0368] The embodiments of the present invention described above are provided for illustrative purposes. Furthermore, these embodiments do not encompass the entirety of the invention, nor do they limit the invention to the disclosed methods. It will be apparent to those skilled in the art that various modifications and variations will be readily understood. These embodiments were chosen and described to most readily explain the principles and applications of the invention. Thus, those skilled in the art can understand the invention through various modifications that are assumed to be optimized for specific uses of various embodiments. The scope of the invention is defined by the foregoing claims and their equivalents.

Claims

1. A resin particle having a parent particle containing a biodegradable resin, wherein, The biodegradable resin is selected from at least one of cellulose acylates and aliphatic polyesters, and the volume average particle size of the resin particles is greater than 3 μm and less than 100 μm. The alkali metal atomic weight A on the surface of resin particles, measured by X-ray photoelectron spectroscopy relative to the total atomic weight of resin particles, and the alkali metal atomic weight B on the surface of resin particles, measured by X-ray fluorescence spectroscopy relative to the total atomic weight of resin particles, satisfy the relationship that 0 ≤ (A / B) < 0.15 and 0.005 atomic% ≤ B ≤ 0.5 atomic% Furthermore, the alkali metal atomic weights measured by X-ray photoelectron spectroscopy, and the alkali metal atomic weights on the surface of the resin particles [AL1], the alkali metal atomic weights on the surface of the resin particles after etching a 2 mm square area of ​​the resin particle surface with an argon cluster ion gun with an output of 5 kV for 5 minutes [AL2], and the alkali metal atomic weights on the surface of the resin particles after etching a 2 mm square area of ​​the resin particle surface with an argon cluster ion gun with an output of 5 kV for 30 minutes [AL3], satisfy the relationship [AL1] < [AL3] < [AL2], where [AL1] is 0 atomic% or more and 0.08 atomic% or less; [AL2] is 0.1 atomic% or more and 10 atomic% or less; and [AL3] is 0.09 atomic% or more and 4 atomic% or less.

2. The resin particles according to claim 1, wherein, The alkali metal includes Na.

3. The resin particles according to claim 1 or 2, wherein, The content of cellulose acylate is 50% by mass or more relative to the total amount of the parent particles.

4. The resin particles according to claim 3, wherein, The cellulose acylated product is a cellulose acylated product having two or more acyl groups.

5. The resin particles according to claim 4, wherein, Cellulose acylated products having two or more of the aforementioned acyl groups are cellulose acetate butyrate.

6. The resin particles according to claim 1 or 2, wherein the surface of the parent particles sequentially comprises: The first layer comprises at least one cationic resin selected from polyalkyleneimide, polyacrylamide, and polyethyleneimine; and The second layer contains anionic or nonionic hydrophobic compounds.

7. The resin particles according to claim 6, wherein, The coating amount of the first layer is between 0.01% and 20% by mass relative to the total amount of the parent particles.

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