Biodegradable resin particles

Abstract

To provide a biodegradable resin particle having a biodegradation speed over time while the initial biodegradation speed is slow.SOLUTION: A biodegradable resin particle includes: a base particle containing a biodegradable resin; a first layer on a surface of the base particle, the first layer containing at least one cationic resin of a polyalkyleneimine, a polyallylamine and a polyvinylamine; and a second layer on the first layer, the second layer containing an anionic or nonionic hydrophobic compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to biodegradable resin particles.

Background Art

[0002] Patent Document 1 discloses a "cellulose material with improved biodegradability by coating with a water-soluble polymer". Patent Document 1 discloses polyethyleneimine as the water-soluble polymer.

[0003] Patent Document 2 discloses "a makeup method for changing the appearance of the skin, changing the touch of the skin, and / or protecting the skin, including the step of applying a self-standing cosmetic sheet containing at least one biocompatible and / or biodegradable hydrophobic polymer layer onto the skin, wherein the self-standing cosmetic sheet has a thickness of 10 to 1000 nm, preferably 30 to 500 nm, more preferably 50 to 300 nm". Patent Document 2 discloses a layer containing polyethyleneimine as the hydrophobic polymer layer.

[0004] Patent Document 3 discloses "a biodegradable resin composition comprising (A) a thermoplastic synthetic resin, (B) an inorganic filler, and (C) a biodegradable organic substance, wherein the blending amount of the component (A) is 49% by mass or less based on the total amount of the composition, and the blending ratio of the component (B) to the component (C) ((B) / (C)) is in the range of 3 / 7 to 7 / 3 by mass ratio". Patent Document 3 discloses that at least one selected from liquid paraffin, metal soap, silicone, side-chain crystalline polyolefin, stearic acid, and polyglutamic acid is blended as the (D) binder component in the biodegradable resin composition.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem of the present invention is to provide biodegradable resin particles having a biodegradation rate over time and a slow initial biodegradation rate compared to biodegradable resin particles having only a layer containing at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine on the surface of mother particles containing a biodegradable resin.

Means for Solving the Problems

[0007] Specific means for solving the above problems include the following aspects.

[0008] <1> Mother particles containing a biodegradable resin, A first layer containing at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine, which is on the surface of the mother particles, A second layer containing an anionic or nonionic hydrophobic compound, which is on the first layer, and biodegradable resin particles having the above. <2> The biodegradable resin particles according to <1>, wherein the hydrophobic compound is at least one selected from the group consisting of silicone compounds, hydrocarbon compounds, fatty acid compounds, acrylic resins, polyester resins, and urethane resins. <3> The biodegradable resin particles according to <2>, wherein the silicone compound is at least one selected from the group consisting of dimethylpolysiloxane, methylpolysiloxane, MQ resin, and silicone rubber. <4> The biodegradable resin particles according to <2> or <3>, wherein the hydrocarbon compound is at least one selected from the group consisting of paraffin wax, microcrystalline wax, polyethylene wax, and polypropylene wax. <5> The biodegradable resin particles according to any one of <2> to <4>, wherein the fatty acid compound is at least one selected from the group consisting of carnauba wax, rice wax, candelilla wax, palm wax, castor oil wax, soybean oil wax, and sunflower oil wax. <6> The biodegradable resin particles according to any one of <1> to <5>, wherein the polyalkyleneimine is a polyalkyleneimine having a structural unit having an alkylene group having 1 to 4 carbon atoms. <7> The biodegradable resin particles according to <6>, wherein the polyalkyleneimine having a structural unit having an alkylene group having 1 to 4 carbon atoms is polyethyleneimine. <8> The biodegradable resin particles according to any one of <1> to <7>, wherein the biodegradable resin is at least one selected from the group consisting of a cellulose resin and a polyester resin. <9> The biodegradable resin particles according to <8>, wherein the biodegradable resin is a cellulose resin. <10> The biodegradable resin particles according to <9>, wherein the cellulose resin is cellulose acetate having two or more acyl groups. <11> The biodegradable resin particles according to <9> or <10>, which do not have a functional group that reacts with the cellulose resin, and include at least one of an aromatic compound having at least one of a phenolic hydroxyl group and a monoglycidyl ether group directly bonded to an aromatic group together with a long-chain aliphatic group, and a fatty acid ester. <12> The biodegradable resin particles according to <11>, wherein the aromatic compound is a cardanol compound. <13> The biodegradable resin particles according to <12>, wherein the cardanol compound is at least one compound selected from the group consisting of a compound represented by the following general formula (CDN1) and a compound represented by the following general formula (CDN1-e). [Chemistry] (In general formula (CDN1), R 1 represents an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. R 2 represents a hydroxy group, a carboxy group, an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. P2 represents an integer of 0 or more and 4 or less. When P2 is 2 or more and there are a plurality of R 2 they may be the same group or different groups.) [Chemistry] (In general formula (CDN1-e), L EP represents a single bond or a divalent linking group. In general formula (CDN1-e), R 1 , R 2 and P2 are respectively synonymous with R 1 , R 2 and P2 in general formula (CDN1).) <14> The biodegradable resin particles according to any one of <11> to <13>, wherein the mother particles contain cellulose acetate propionate as the cellulose resin and a cardanol compound as the aromatic compound. <15> The biodegradable resin particles according to any one of <11> to <13>, wherein the mother particles contain cellulose acetate butyrate as the cellulose resin and the fatty acid ester. <16> The biodegradable resin particles according to any one of <1> to <15>, wherein the mass ratio of the coating amount of the cationic resin to the coating amount of the hydrophobic compound (coating amount of the cationic resin / coating amount of the hydrophobic compound) is 0.1 or more and 10 or less. <17> The biodegradable resin particles according to <16>, wherein the coating amount of the cationic resin with respect to the mother particles is 0.1% by mass or more and 10% by mass or less. <18> The biodegradable resin particles according to any one of <1> to <17>, wherein the number average molecular weight of the cationic resin is 10,000 or more and 85,000 or less. <19> Mother particles containing a biodegradable resin, A compound layer on the surface of the mother particles, having, Biodegradable resin particles having a water contact angle of 70° or more and 120° or less when the biodegradable resin particles are pelletized. <20> Mother particles containing a biodegradable resin, A compound layer on the surface of the mother particles, having, Biodegradable resin particles having an aerobic biodegradation rate of 20% or less after 3 months measured by a method according to ISO - 14855 - 2 (2018). <21> Mother particles containing a biodegradable resin, A compound layer on the surface of the mother particles, having, Biodegradable resin particles in which when the surface of the biodegradable resin particles is measured by X - ray photoelectron spectroscopy (XPS), the relationship between the carbon atomic weight Cs, the silicon atomic weight Sis, and the oxygen atomic weight Os satisfies the formula A: (Cs + Sis) / Os ≥ 3. <22> The biodegradable resin particles according to <21>, in which when the surface of the biodegradable resin particles after 3 minutes of surface etching is measured by X - ray photoelectron spectroscopy (XPS), the relationship between the carbon atomic weight Ce, the silicon atomic weight Sie, and the oxygen atomic weight Oe satisfies the formula B: (Ce + Sie) / Oe ≥ 3.

Advantages of the Invention

[0009] According to the invention according to <1>, <2>, <3>, <4>, <5>, <6>, <7>, or <8>, compared with biodegradable resin particles having only a layer containing at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine on the surface of mother particles containing a biodegradable resin, biodegradable resin particles having a biodegradation rate over time and a slow initial biodegradation rate are provided. According to the invention according to <9>, biodegradable resin particles are provided that have a faster biodegradation rate over time and a slower initial biodegradation rate compared to the case where the biodegradable resin is a polyester resin. According to the invention according to <10>, biodegradable resin particles are provided that have a faster biodegradation rate over time and a slower initial biodegradation rate compared to the case where the cellulose resin is a cellulose acylate having one type of acyl group. According to the invention according to <11>, compared to biodegradable resin particles having only a layer containing at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine on the surface of the mother particles containing the biodegradable resin, even when containing an aromatic compound and at least one of fatty acid esters together with a cellulose resin as the biodegradable resin, biodegradable resin particles are provided that have biodegradability and excellent hydrolysis resistance. According to the invention according to <12> or <13>, biodegradable resin particles are provided that have biodegradability and excellent hydrolysis resistance compared to the case where an alkyl-modified product of a phenol novolac type epoxy resin is applied as the aromatic compound. According to the invention according to <14> or <15>, when the mother particles contain cellulose acetate butyrate as the cellulose resin and a cardanol compound as the aromatic compound, or when the mother particles contain cellulose acetate propionate as the cellulose resin and a fatty acid ester, compared to these cases, biodegradable resin particles are provided that have biodegradability and excellent hydrolysis resistance.

[0010] According to the invention according to <16>, biodegradable resin particles are provided that have a faster biodegradation rate over time and a slower initial biodegradation rate compared to the case where the mass ratio of the cationic resin to the hydrophobic compound is less than 0.1 or more than 10. According to the invention according to <17>, biodegradable resin particles are provided that have a faster biodegradation rate over time and a slower initial biodegradation rate compared to the case where the coating amount of the cationic resin on the mother particles is less than 0.1 mass% or more than 10 mass%. According to the invention according to <18>, biodegradable resin particles are provided which have a faster biodegradation rate over time and a slower initial biodegradation rate compared to the case where the number average molecular weight of the cationic resin is less than 10,000 or exceeds 85,000.

[0011] According to the invention according to <19>, biodegradable resin particles are provided which have a biodegradation rate over time and a slower initial biodegradation rate compared to biodegradable resin particles having a compound layer on the surface of the mother particles containing the biodegradable resin and a water contact angle of less than 70° when the biodegradable resin particles are pelletized. According to the invention according to <20>, biodegradable resin particles are provided which have a biodegradation rate over time and a slower initial biodegradation rate compared to biodegradable resin particles having a compound layer on the surface of the mother particles containing the biodegradable resin and having an aerobic biodegradation rate of more than 20% after 3 months measured by a method according to ISO - 14855 - 2 (2018). According to the invention according to <21>, biodegradable resin particles are provided which have a biodegradation rate over time and a slower initial biodegradation rate compared to biodegradable resin particles having a compound layer on the surface of the mother particles containing the biodegradable resin and not satisfying the formula A: (Cs + Sis) / Os ≥ 3. According to the invention according to <22>, biodegradable resin particles are provided which have a biodegradation rate over time and a slower initial biodegradation rate compared to biodegradable resin particles having a compound layer on the surface of the mother particles containing the biodegradable resin and not satisfying the formula B: (Ce + Sie) / Oe ≥ 3.

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments which are an example of the present invention will be described. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the embodiments.

[0013] In the numerical ranges described step - by - step in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical ranges described in other step - by - step descriptions. Also, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.

[0014] In this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved. Each component may contain a plurality of corresponding substances. When referring to the amount of each component, if there are a plurality of substances corresponding to each component, unless otherwise specified, it means the total amount of the plurality of substances. "(Meth)acryl" means at least one of acrylic and methacrylic, and "(meth)acrylate" means at least one of acrylate and methacrylate.

[0015] <Biodegradable resin particles> - First Embodiment - The biodegradable resin particles according to the first embodiment include mother particles containing a biodegradable resin, a first layer containing at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine on the surface of the mother particles, and a second layer containing an anionic or nonionic hydrophobic compound on the first layer.

[0016] The biodegradable resin particles according to the first embodiment, with the above configuration, have a biodegradation rate over time (for example, 12 months under aerobic conditions) while having a slow biodegradation rate in the initial stage (for example, 3 months under aerobic conditions). The reason is speculated as follows.

[0017] Biodegradable resin particles are required to have a fast biodegradation rate. However, if the biodegradation rate is too fast, the durability of the resin particles themselves will decrease rapidly. That is, during a certain period (for example, a period of several years during the use period), it is required to maintain the function as resin particles.

[0018] Therefore, a second layer containing an anionic or nonionic hydrophobic compound is provided on the surface of the mother particles containing the biodegradable resin via a first layer containing at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine. Due to the presence of the first layer containing a cationic resin, an anionic or nonionic hydrophobic compound is adsorbed on the surface of the mother particles to form a hydrophobic second layer, thereby increasing the hydrophobicity of the surface of the biodegradable resin particles. As a result, the initial biodegradation rate becomes slow, and for a certain period, the function as resin particles is maintained. Then, as the biodegradation of the hydrophobic compound in the second layer proceeds over time, the biodegradability of the mother particles themselves containing the biodegradable resin is exhibited over time.

[0019] Therefore, it is presumed that the biodegradable resin particles according to the first embodiment are biodegradable resin particles having a biodegradation rate over time while having a slow initial biodegradation rate.

[0020] - Second Embodiment - The biodegradable resin particles according to the second embodiment have a mother particle containing a biodegradable resin and a compound layer on the surface of the mother particle, and the water contact angle when the biodegradable resin particles are pelletized is 70° or more and 120° or less.

[0021] The biodegradable resin particles according to the second embodiment become biodegradable resin particles having a biodegradation rate over time (for example, 12 months under aerobic conditions) while having a slow initial (for example, 3 months under aerobic conditions) biodegradation rate due to the above configuration. The reason is that the surface of the compound layer in the biodegradable resin particles shows hydrophobicity within the range of the above contact angle, and the hydrolysis of the biodegradable resin of the mother particle is suppressed to slow down the initial biodegradation rate, and for a certain period, the function as resin particles is maintained. Then, after a certain period has passed, the decomposition of the components of the compound layer of the biodegradable resin particles proceeds, so that the biodegradability of the mother particles themselves containing the biodegradable resin is exhibited over time.

[0022] - Third Embodiment - The biodegradable resin particles according to the third embodiment have a mother particle containing a biodegradable resin and a compound layer on the surface of the mother particle, and the aerobic biodegradation rate after 3 months measured by a method according to ISO - 14855 - 2 (2018) is 20% or less. The biodegradable resin particles according to the third embodiment are biodegradable resin particles that have a biodegradation rate over time (for example, 12 months under aerobic conditions) while having a slow biodegradation rate in the initial stage (for example, 3 months under aerobic conditions) due to the above configuration. The reason is that the compound layer in the biodegradable resin particles lowers the aerobic biodegradation rate after 3 months, suppresses the hydrolyzability of the biodegradable resin of the mother particle, slows down the initial biodegradation rate, and for a certain period, the function as resin particles is maintained. Then, after a certain period has elapsed, since the decomposition of the components of the compound layer of the biodegradable resin particles progresses, over time, the biodegradability of the mother particle itself containing the biodegradable resin is exhibited.

[0023] -Fourth Embodiment- The biodegradable resin particles according to the fourth embodiment have a mother particle containing a biodegradable resin and a compound layer on the surface of the mother particle. When the surface of the biodegradable resin particles is measured by X-ray photoelectron spectroscopy (XPS), the relationship between the carbon atomic weight Cs, the silicon atomic weight Sis, and the oxygen atomic weight Os satisfies the formula A: (Cs + Sis) / Os ≥ 3. The biodegradable resin particles according to the fourth embodiment are biodegradable resin particles that have a biodegradation rate over time (for example, 12 months under aerobic conditions) while having a slow biodegradation rate in the initial stage (for example, 3 months under aerobic conditions) due to the above configuration. The reason is that the compound layer in the biodegradable resin particles increases the amount of carbon atoms and silicon atoms present on the surface of the biodegradable resin particles so as to satisfy formula A, thereby increasing the hydrophobicity of the surface of the biodegradable resin particles, suppressing the hydrolyzability of the biodegradable resin of the mother particle, slowing down the initial biodegradation rate, and for a certain period, the function as resin particles is maintained. Then, after a certain period has elapsed, since the decomposition of the components of the compound layer of the biodegradable resin particles progresses, over time, the biodegradability of the mother particle itself containing the biodegradable resin is exhibited.

[0024] Also, by increasing the amount of carbon atoms and silicon atoms present on the particle surface, the lipophilicity of the surface of the biodegradable resin particles is improved, and the oil absorption rate of the resin particles increases. Conventional biodegradable resin particles are excellent in degradability in the natural environment. However, since their structure is relatively hydrophilic, their compatibility with oil or oil absorption capacity is low. For example, when conventional biodegradable resin particles are added to cosmetics or the like, due to their low oil absorption capacity, makeup smudging is likely to occur due to sebum or the like. Also, when conventional biodegradable resin particles are added to paints, if their oil absorption capacity is low and their compatibility with oil is poor, a phenomenon of aggregation and solidification occurs. Therefore, biodegradable resin particles with a high oil absorption rate are useful in fields such as cosmetics and paints. For example, even when added to cosmetics, makeup smudging is less likely to occur, and even when added to paints, they are less likely to aggregate.

[0025] Here, in the biodegradable resin particles according to the second to fourth embodiments, for example, as the compound layer, there is a two-layer compound layer including a first layer containing at least one cationic resin such as polyalkyleneimine, polyallylamine, and polyvinylamine, and a second layer having an anionic or nonionic hydrophobic compound on the first layer. However, in the biodegradable resin particles according to the second and third embodiments, for example, the compound layer is not particularly limited as long as it is a compound layer that imparts the above characteristics to the biodegradable resin particles according to the second and third embodiments.

[0026] Hereinafter, biodegradable resin particles (hereinafter also referred to as "biodegradable resin particles according to the present embodiment") that correspond to any of the first to fourth embodiments of the biodegradable resin particles will be described in detail. However, an example of the biodegradable resin particles of the present invention may be any biodegradable resin particles that correspond to any of the first to fourth embodiments of the biodegradable resin particles.

[0027] Hereinafter, the biodegradable resin particles according to the present embodiment will be described in detail.

[0028] [Mother particles] The mother particles are the particles on which the first layer and the second layer are formed and contain a biodegradable resin. The mother particles include particles mainly composed of a biodegradable resin. Specifically, examples include particles containing 90% by mass, 95% by mass, 98% by mass, or 100% by mass of the biodegradable resin with respect to the entire mother particles.

[0029] -Biodegradable resin- A biodegradable resin is a resin that is decomposed by microorganisms into water and carbon dioxide. Specifically, a biodegradable resin means a resin with an aerobic biodegradation rate of 50% or more in one month as measured by a method conforming to ISO-14855-2 (2018).

[0030] Examples of biodegradable resins include polyester resins, natural polymers, polyvinyl alcohol, etc.

[0031] Examples of polyester resins include aliphatic polyester resins, aliphatic-aromatic polyester resins, etc. Examples of aliphatic polyester resins include polyhydroxyalkanoic acids such as polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxybutyrate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), polycaprolactone, polybutylene succinate (PBS), polybutylene succinate / adipate (PBSA), polyethylene succinate (PBA), etc. Examples of aliphatic-aromatic polyester resins include polybutylene adipate / terephthalate copolymer resin (PBAH), polytetramethylene adipate / terephthalate copolymer resin, etc.

[0032] Examples of natural polymers include starch, cellulose, chitin, chitosan, gluten, gelatin, zein, soy protein, collagen, keratin, etc.

[0033] Among these, as biodegradable resins, from the viewpoint of improving the biodegradation rate over time, at least one selected from the group consisting of cellulose resins and polyester resins is preferred, and cellulose resins are more preferred.

[0034] As the cellulose resin, cellulose acylate is preferred. Cellulose acylate is a cellulose derivative in which at least a part of the hydroxy groups in cellulose is substituted (acylated) with an acyl group. The acyl group is a group having the structure of -CO-R AC (R AC represents a hydrogen atom or a hydrocarbon group.).

[0035] Cellulose acylate is, for example, a cellulose derivative represented by the following general formula (CA).

[0036]

Chemical formula

[0037] In the general formula (CA), A 1 , A 2 and A 3 each independently represents a hydrogen atom or an acyl group, and n represents an integer of 2 or more. However, at least a part of the n A 1 , the n A 2 and the n A 3 represents an acyl group. The n A 1 in the molecule may all be the same, partly the same, or different from each other. Similarly, the n A 2 and the n A 3 in the molecule may each be all the same, partly the same, or different from each other.

[0038] A 1 , A 2 and A 3 The acyl group represented by may be linear, branched, or cyclic, but is preferably linear or branched, and more preferably linear.

[0039] A 1 , A 2 and A 3The acyl group represented by the formula (I) may have a hydrocarbon group which is either a saturated hydrocarbon group or an unsaturated hydrocarbon group, but is more preferably a saturated hydrocarbon group.

[0040] A 1 , A 2 and A 3 The acyl group represented by the formula (I) is preferably an acyl group having a carbon number of 1 to 6. That is, the cellulose acylate is preferably an acyl group having a carbon number of 1 to 6.

[0041] A 1 , A 2 and A 3 The acyl group represented by may be a group in which a hydrogen atom in the acyl group is substituted with a halogen atom (for example, a fluorine atom, a bromine atom, an iodine atom), an oxygen atom, a nitrogen atom or the like, but is preferably unsubstituted.

[0042] A 1 , A 2 and A 3 Examples of the acyl group represented by include a formyl group, an acetyl group, a propionyl group, a butyryl group (butanoyl group), a propenoyl group, a hexanoyl group, etc. Among these, from the viewpoint of improving the biodegradation rate of the resin particles, the acyl group is more preferably an acyl group having 2 to 4 carbon atoms, and even more preferably an acyl group having 2 or 3 carbon atoms.

[0043] Examples of the cellulose acylate include cellulose acetate (cellulose monoacetate, cellulose diacetate (DAC), cellulose triacetate), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB).

[0044] From the perspective of improving the biodegradation rate of resin particles, cellulose acylate preferably has two or more types of acyl groups. Specifically, as cellulose acylate, from the perspective of improving the biodegradation rate of resin particles, cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) are preferred, and cellulose acetate propionate (CAP) is more preferred.

[0045] Cellulose acylate may be used alone or in combination of two or more.

[0046] The weight-average degree of polymerization of cellulose acylate is preferably 200 or more and 1000 or less, more preferably 500 or more and 1000 or less, and still more preferably 600 or more and 1000 or less.

[0047] The weight-average degree of polymerization of cellulose acylate is determined from the weight-average molecular weight (Mw) by the following procedure. First, the weight-average molecular weight (Mw) of cellulose acylate is measured in terms of polystyrene using a gel permeation chromatography apparatus (GPC apparatus: manufactured by Tosoh Corporation, HLC-8320GPC, column: TSKgel α-M) with tetrahydrofuran. Next, the degree of polymerization of cellulose acylate is determined by dividing by the molecular weight of the constituent unit of cellulose acylate. For example, when the substituent of cellulose acylate is an acetyl group, the molecular weight of the constituent unit is 263 when the degree of substitution is 2.4 and 284 when the degree of substitution is 2.9.

[0048] From the perspective 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, still more preferably 2.3 or more and 2.9 or less, and particularly preferably 2.6 or more and 2.9 or less.

[0049] In cellulose acetate propionate (CAP), the ratio of the degree of substitution of the acetyl group to the propionyl group (acetyl group / propionyl group) is preferably 0.01 or more and 1 or less, more preferably 0.05 or more and 0.1 or less, from the viewpoint of improving the biodegradation rate of the resin particles.

[0050] In cellulose acetate butyrate (CAB), the ratio of the degree of substitution of the acetyl group to the butyryl group (acetyl group / butyryl group) is preferably 0.05 or more and 3.5 or less, more preferably 0.5 or more and 3.0 or less, from the viewpoint of improving the biodegradation rate of the resin particles.

[0051] The degree of substitution of cellulose acylate is an index indicating the degree to which the hydroxy groups possessed by cellulose are substituted by acyl groups. That is, the degree of substitution is an index indicating the degree of acylation of cellulose acylate. Specifically, the degree of substitution means the average number of substitutions of the three hydroxy groups in the D-glucopyranose unit of cellulose acylate by acyl groups within the molecule. The degree of substitution is 1 determined from the integration ratio of the peaks of hydrogen derived from cellulose and hydrogen derived from acyl groups by 1H-NMR (JMN-ECA manufactured by JEOL RESONANCE).

[0052] These biodegradable resins may be used alone or in combination of two or more.

[0053] -Other components- The mother particles may contain other components. Examples of other components include plasticizers, flame retardants, compatibilizers, mold release agents, light stabilizers, weathering agents, colorants, pigments, modifiers, anti-dripping agents, antistatic agents, hydrolysis inhibitors, fillers, reinforcing agents (such as glass fibers, carbon fibers, talc, clay, mica, glass flakes, milled glass, glass beads, crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, etc.), acid acceptors for preventing acetic acid release (oxides such as magnesium oxide and aluminum oxide; metal hydroxides such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, hydrotalcite, etc.; calcium carbonate; talc; etc.), reactive trap agents (such as epoxy compounds, acid anhydride compounds, carbodiimides, etc.). The content of each of the other components is preferably 0% by mass or more and 5% by mass or less based on the total amount of the mother particles. Here, "0% by mass" means not containing the other components.

[0054] Examples of plasticizers include ester compounds, camphor, metal soaps, polyols, polyalkylene oxides, etc. From the viewpoint of improving the mechanical properties of the resin particles, ester compounds are preferred as plasticizers. The plasticizer may be used alone or in combination of two or more.

[0055] Examples of ester compounds include fatty acid esters (adipic acid esters, citric acid esters, sebacic acid esters, azelaic acid esters, phthalic acid esters, acetic acid esters), phosphate esters, condensed phosphate esters, glycol esters (such as glycol benzoate), modified fatty acid esters (such as epoxidized fatty acid esters), etc. Examples of the above esters include monoesters, diesters, triesters, polyesters, etc. Among them, dicarboxylic acid diesters (such as adipic acid diesters, sebacic acid diesters, azelaic acid diesters, phthalic acid diesters) are preferred.

[0056] As the plasticizer, an adipic acid ester is preferable. The adipic acid ester has a high affinity with cellulose acylate and disperses in a state closer to uniform with respect to cellulose acylate, thereby improving the thermal fluidity more than other plasticizers.

[0057] As the adipic acid ester, a mixture of an adipic acid ester and other components may be used. Examples of commercially available products of such a mixture include Daifatty 101 manufactured by Daihachi Chemical Industry Co., Ltd.

[0058] Examples of fatty acid esters such as citrate, sebacate, azelate, phthalate, acetate, etc. include esters of fatty acids and alcohols. Examples of the alcohol include monohydric alcohols such as methanol, ethanol, propanol, butanol, 2-ethylhexanol; polyhydric alcohols such as glycerin, polyglycerin (diglycerin, etc.), pentaerythritol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, trimethylolpropane, trimethylolethane, sugar alcohol; and the like.

[0059] Examples of the glycol in the benzoic acid glycol ester include ethylene glycol, diethylene glycol, propylene glycol, etc.

[0060] Epoxidized fatty acid esters are ester compounds having a structure in which the carbon-carbon unsaturated bond of an unsaturated fatty acid ester is epoxidized (that is, oxacyclopropane). Examples of epoxidized fatty acid esters include esters of fatty acids in which some or all of the carbon-carbon unsaturated bonds in unsaturated fatty acids (for example, oleic acid, palmitoleic acid, vaccenic acid, linoleic acid, linolenic acid, nervonic acid, etc.) are epoxidized and alcohols. Examples of the alcohol include monohydric alcohols such as methanol, ethanol, propanol, butanol, 2-ethylhexanol; polyhydric alcohols such as glycerin, polyglycerin (diglycerin, etc.), pentaerythritol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, trimethylolpropane, trimethylolethane, sugar alcohol; and the like.

[0061] The ester compound as a plasticizer preferably has a molecular weight (or weight average molecular weight) of 200 or more and 2000 or less, more preferably 250 or more and 1500 or less, and still more preferably 280 or more and 1000 or less. The weight average molecular weight of the ester compound is a value measured in accordance with the measurement method of the weight average molecular weight of cellulose acylate unless otherwise specified.

[0062] Here, when a cellulose resin is applied as a biodegradable resin, the master particles preferably contain, together with the cellulose resin, as a plasticizer, an aromatic compound having no functional group reactive with the cellulose resin and having at least one of a phenolic hydroxyl group and a monoglycidyl ether group directly bonded to an aromatic group together with a long-chain aliphatic group (hereinafter also referred to as "aromatic compound (B1)"), and at least one kind of fatty acid ester (hereinafter also referred to as "fatty acid ester (B2)"). Cellulose resin is difficult to hydrolyze alone, but it is difficult to perform molding processing because of its poor flexibility. Therefore, it is preferable to add a plasticizer to the cellulose resin to impart flexibility. However, the cellulose resin to which a plasticizer is added is liable to hydrolyze. Therefore, coating a second layer containing a hydrophobic compound on the master particle containing the cellulose resin and the plasticizer is effective in imparting hydrolysis resistance while ensuring biodegradability. On the other hand, in order to slow down the initial biodegradation rate, it is preferable that the second layer containing the hydrophobic compound is firmly coated by the master particle.

[0063] In this regard, when at least one of an aromatic compound (B1) and a fatty acid ester (B2) is adopted as the plasticizer to be contained in the master particle, a first layer containing a cationic resin that functions as an adhesive layer between the surface of the master particle and the second layer containing the hydrophobic compound is more firmly coated on the surface of the master particle. As a result, the second layer containing the hydrophobic compound is more firmly coated on the master particle, and high hydrolysis resistance can be imparted to the biodegradable resin particles while ensuring biodegradability. The reason is presumed as follows.

[0064] Since the aromatic compound (B1) has a benzene ring, the benzene ring attracts electrons and the OH group becomes more acidic. Therefore, the reactivity with the cationic compound is high. Further, since the fatty acid ester (B2) is a more acidic compound, the reactivity with the cationic compound is high. As a result, the first layer containing the cationic resin is more firmly coated on the surface of the master particle. Therefore, it is presumed that the second layer containing the hydrophobic compound is more firmly coated on the master particle, and high hydrolysis resistance can be imparted to the biodegradable resin particles while ensuring biodegradability. As a result, biodegradable resin particles excellent in hydrolysis resistance while ensuring biodegradability are obtained.

[0065] In particular, from the viewpoint of ensuring biodegradability and improving hydrolysis resistance, when cellulose acetate propionate is applied as the cellulose resin, it is preferable to apply a cardanol compound as the aromatic compound as the plasticizer. From the same perspective, when applying cellulose acetate propionate as the cellulose resin, it is preferable to apply an aliphatic ester as the plasticizer.

[0066] Hereinafter, the aromatic compound (B1) will be described. The aromatic compound (B1) is an aromatic compound that has no functional group reactive with the cellulose resin and has at least one of a phenolic hydroxyl group and a monoglycidyl ether group directly bonded to an aromatic group together with a long-chain aliphatic group. That is, the aromatic compound (B1) is a compound that has no functional group reactive with the cellulose acylate (A), has a long-chain aliphatic group, and has at least one of a phenolic hydroxyl group and a monoglycidyl ether group. Here, the long-chain aliphatic group includes a saturated aliphatic group (alkyl group), an unsaturated aliphatic group (alkenyl group, alkynyl group) having 6 to 30 carbon atoms (preferably 10 to 20 carbon atoms). The aliphatic group may be linear, branched, or cyclic, but linear and branched are preferred, and linear is more preferred.

[0067] Examples of the aromatic compound (B1) include compounds in which a phenolic hydroxyl group is substituted on a monocyclic ring, a condensed ring (a polycyclic ring having two or more aromatic rings), a polynuclear ring (a polycyclic ring in which aromatic rings are bonded by carbon-carbon bonds), a heterocyclic ring (a monocyclic heterocyclic ring, a condensed ring containing a heterocyclic ring, a polynuclear ring containing a heterocyclic ring, etc.) together with a long-chain aliphatic group.

[0068] Specific examples of the aromatic compound (B1) include cardanol compounds, phenalkamine compounds, phenolic resins, phenol novolak type epoxy resins, phenol resol type epoxy resins, phenol-modified palm oil, phenol-modified soybean oil, phenol-modified linseed oil, and the like. Among these, from the viewpoint of improving biodegradability, the aromatic compound (B1) is preferably a cardanol compound.

[0069] The cardanol compound refers to a component contained in a natural compound derived from cashew nuts as a raw material (for example, compounds represented by the following structural formulas (b-1) to (b-4)) or a derivative from said component.

[0070]

Chem.

[0071] The cardanol compound may be a mixture of natural compounds derived from cashew nuts as a raw material (hereinafter also referred to as "cashew nut-derived mixture").

[0072] The cardanol compound may be a derivative from the cashew nut-derived mixture. Examples of derivatives from the cashew nut-derived mixture include the following mixtures, monomers, etc.

[0073] · A mixture with the composition ratio of each component in the cashew nut-derived mixture adjusted · A monomer obtained by isolating only a specific component from the cashew nut-derived mixture · A mixture containing a modified product of the components in the cashew nut-derived mixture · A mixture containing a polymer obtained by polymerizing the components in the cashew nut-derived mixture · A mixture containing a modified polymer obtained by modifying and polymerizing the components in the cashew nut-derived mixture · A mixture containing a modified product obtained by further modifying the components in the mixture with the adjusted composition ratio · A mixture containing a polymer obtained by further polymerizing the components in the mixture with the adjusted composition ratio · A mixture containing a modified polymer obtained by further modifying and polymerizing the components in the mixture with the adjusted composition ratio · A modified product obtained by further modifying the isolated monomer · A polymer obtained by further polymerizing the isolated monomer · A modified polymer obtained by further modifying and polymerizing the isolated monomer Here, the monomer is assumed to include multimers such as dimers and trimers.

[0074] The cardanol compound is preferably at least one compound selected from the group consisting of a compound represented by the general formula (CDN1) and a polymer obtained by polymerizing the compound represented by the general formula (CDN1) from the viewpoint of improving the biodegradation rate of resin particles.

[0075]

Chemical formula

[0076] In the general formula (CDN1), R 1 represents an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. R 2 represents a hydroxy group, a carboxy group, an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. P2 represents an integer of 0 or more and 4 or less. When P2 is 2 or more and a plurality of R 2 are present, they may be the same group or different groups.

[0077] In the general formula (CDN1), the alkyl group which may have a substituent represented by R 1 is preferably an alkyl group having 3 or more and 30 or less carbon atoms, more preferably an alkyl group having 5 or more and 25 or less carbon atoms, and still more preferably an alkyl group having 8 or more and 20 or less carbon atoms. Examples of the substituent include a hydroxy group; a substituent containing an ether bond such as an epoxy group or a methoxy group; a substituent containing an ester bond such as an acetyl group or a propionyl group; and the like. Examples of the alkyl group which may have a substituent include a pentadecane-1-yl group, a heptane-1-yl group, an octane-1-yl group, a nonane-1-yl group, a decane-1-yl group, an undecane-1-yl group, a dodecane-1-yl group, a tetradecane-1-yl group, and the like.

[0078] In the general formula (CDN1), R 1The unsaturated aliphatic group having a double bond represented by and optionally having a substituent is preferably an unsaturated aliphatic group having 3 to 30 carbon atoms, more preferably an unsaturated aliphatic group having 5 to 25 carbon atoms, and still more preferably an unsaturated aliphatic group having 8 to 20 carbon atoms. The number of double bonds in the unsaturated aliphatic group is preferably 1 to 3. Examples of the substituent include those listed as the substituent of the alkyl group. Examples of the unsaturated aliphatic group having a double bond and optionally having a substituent include pentadeca-8-en-1-yl group, pentadeca-8,11-dien-1-yl group, pentadeca-8,11,14-trien-1-yl group, pentadeca-7-en-1-yl group, pentadeca-7,10-dien-1-yl group, pentadeca-7,10,14-trien-1-yl group, and the like.

[0079] In general formula (CDN1), R 1 is preferably a pentadeca-8-en-1-yl group, a pentadeca-8,11-dien-1-yl group, a pentadeca-8,11,14-trien-1-yl group, a pentadeca-7-en-1-yl group, a pentadeca-7,10-dien-1-yl group, or a pentadeca-7,10,14-trien-1-yl group.

[0080] In general formula (CDN1), R 2 The optionally substituted alkyl group and the unsaturated aliphatic group having a double bond and optionally having a substituent represented by are preferably the same as those listed as the optionally substituted alkyl group and the unsaturated aliphatic group having a double bond and optionally having a substituent represented by R 1 Examples thereof.

[0081] The compound represented by the general formula (CDN1) may be further modified. For example, it may be epoxidized. From the viewpoint of improving the biodegradation rate of the resin particles, specifically, it is preferable that the compound is a compound having a structure in which the hydroxy group of the compound represented by the general formula (CDN1) is replaced by the following group (EP), that is, a compound represented by the following general formula (CDN1-e).

[0082]

Chemical formula

[0083] In the group (EP) and the general formula (CDN1-e), L EP represents a single bond or a divalent linking group. In the general formula (CDN1-e), R 1 , R 2 and P2 are respectively synonymous with R 1 , R 2 and P2 in the general formula (CDN1).

[0084] In the group (EP) and the general formula (CDN1-e), examples of the divalent linking group represented by L EP include an alkylene group which may have a substituent (preferably an alkylene group having 1 to 4 carbon atoms, more preferably an alkylene group having 1 carbon atom), -CH 2 CH 2 OCH 2 CH 2 - group and the like. Examples of the above-mentioned substituent include those enumerated as substituents in R 1 of the general formula (CDN1).

[0085] L EP is preferably a methylene group.

[0086] The polymer obtained by polymerizing the compound represented by the general formula (CDN1) refers to a polymer in which at least two or more compounds represented by the general formula (CDN1) are polymerized with or without a linking group.

[0087] Examples of the polymer obtained by polymerizing the compound represented by the general formula (CDN1) include the compound represented by the following general formula (CDN2).

[0088]

Chemical formula

[0089] In the general formula (CDN2), R 11 , R 12 and R 13 each independently represent an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. R 21 , R 22 and R 23 each independently represent a hydroxy group, a carboxy group, an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. P21 and P23 each independently represent an integer of 0 or more and 3 or less, and P22 represents an integer of 0 or more and 2 or less. L 1 and L 2 each independently represent a divalent linking group. n represents an integer of 0 or more and 10 or less. When P21 is 2 or more, the plurality of R 21 , when P22 is 2 or more, the plurality of R 22 , and when P23 is 2 or more, the plurality of R 23 may each be the same group or different groups. When n is 2 or more, the plurality of R 12 , R 22 and L 1 may each be the same group or different groups, and when n is 2 or more, the plurality of P22 may be the same number or different numbers.

[0090] In the general formula (CDN2), R 11 , R 12 , R 13 , R 21 , R 22 and R 23An alkyl group which may have a substituent represented by and an unsaturated aliphatic group which has a double bond and may have a substituent, examples of which are preferably the same as those listed as R in the general formula (CDN1). 1 Those listed as are also preferably cited as examples.

[0091] In the general formula (CDN2), L 1 and L 2 Examples of the divalent linking group represented by include, for example, an alkylene group which may have a substituent (preferably an alkylene group having 2 to 30 carbon atoms, more preferably an alkylene group having 5 to 20 carbon atoms), and the like. Examples of the above-mentioned substituent are the same as those listed as substituents in R of the general formula (CDN1). 1

[0092] In the general formula (CDN2), n is preferably 1 or more and 10 or less, more preferably 1 or more and 5 or less.

[0093] The compound represented by the general formula (CDN2) may be further modified. For example, it may be epoxidized. Specifically, it may be a compound having a structure in which the hydroxy group of the compound represented by the general formula (CDN2) is replaced by a group (EP), that is, a compound represented by the following general formula (CDN2-e).

[0094]

Chemical formula

[0095] 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 R in the general formula (CDN2). 11 , R 12 , R 13 , R 21 , R 22 , R​23 , P21, P22, P23, L 1 , L 2 and is synonymous with n. In general formula (CDN2-e), L EP1 , L EP2 and L EP3 each independently represents a single bond or a divalent linking group. When n is 2 or more, a plurality of Ls EP2 may be the same group or different groups.

[0096] In general formula (CDN2-e), L EP1 , L EP2 and L EP3 The divalent linking group represented by is preferably exemplified by the same ones as those listed as the divalent linking group represented by L in general formula (CDN1-e). EP

[0097] As the polymer obtained by polymerizing the compound represented by general formula (CDN1), for example, a polymer obtained by three-dimensionally crosslinking and polymerizing at least three or more compounds represented by general formula (CDN1) with or without a linking group may be used. Examples of the polymer obtained by three-dimensionally crosslinking and polymerizing the compound represented by general formula (CDN1) include compounds represented by the following structural formulas.

[0098]

Chemical formula

[0099] In the above structural formula, R 10 , R 20 and P20 are respectively synonymous with R 1 , R 2 and P2 in general formula (CDN1). L 10 represents a single bond or a divalent linking group. A plurality of Rs 10 , R 20 and L 10 may be the same group or different groups. A plurality of Ps 20 may be the same number or different numbers.

[0100] In the above structural formula, L 10 Examples of the divalent linking group represented by include an alkylene group which may have a substituent (preferably an alkylene group having 2 to 30 carbon atoms, more preferably an alkylene group having 5 to 20 carbon atoms), and the like. Examples of the above substituent are the same as those listed as substituents in R of general formula (CDN1). 1

[0101] The compound represented by the above structural formula may be further modified. For example, it may be epoxidized. Specifically, it may be a compound having a structure in which the hydroxy group of the compound represented by the above structural formula is replaced by a group (EP). For example, a compound represented by the following structural formula, that is, a polymer in which the compound represented by general formula (CDN1-e) is three-dimensionally crosslinked and polymerized can be mentioned.

[0102]

Chemical formula

[0103] In the above structural formula, R 10 , R 20 and P20 are synonymous with R 1 , R 2 and P2 in general formula (CDN1-e), respectively. L 10 represents a single bond or a divalent linking group. A plurality of R 10 , R 20 and L 10 may each be the same group or different groups. A plurality of P 20 may be the same number or different numbers.

[0104] In the above structural formula, L 10 Examples of the divalent linking group represented by include an alkylene group which may have a substituent (preferably an alkylene group having 2 to 30 carbon atoms, more preferably an alkylene group having 5 to 20 carbon atoms), and the like. Examples of the above substituent are the same as those of R of general formula (CDN1).​1 Those listed as substituents can be similarly listed.

[0105] From the viewpoint of improving the transparency of the resin molded body, the cardanol compound preferably contains a cardanol compound having an epoxy group, and more preferably is a cardanol compound having an epoxy group.

[0106] Commercially available products may be used as the cardanol compound. Examples of commercially available products 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, LB-7000, LB-7250, CD-5L manufactured by Tohoku Chemical Industry Co., Ltd., etc. Examples of commercially available products of cardanol compounds having an epoxy group include NC-513, NC-514S, NC-547, LITE513E, Ultra LTE 513 manufactured by Cardolite, etc.

[0107] From the viewpoint of improving the biodegradation rate of the resin molded body, the hydroxyl value of the cardanol compound is preferably 100 mgKOH / g or more, more preferably 120 mgKOH / g or more, and still more preferably 150 mgKOH / g or more. The measurement of the hydroxyl value of the cardanol compound is carried out according to Method A of ISO14900.

[0108] When a cardanol compound having an epoxy group is used as the cardanol compound, from the viewpoint of improving the transparency of the resin molded body, the epoxy equivalent is preferably 300 or more and 500 or less, more preferably 350 or more and 480 or less, and still more preferably 400 or more and 470 or less. The measurement of the epoxy equivalent of the cardanol compound having an epoxy group is carried out according to ISO3001.

[0109] From the viewpoint of improving the biodegradation rate of the resin molded body, the molecular weight of the cardanol compound is preferably 250 or more and 1000 or less, more preferably 280 or more and 800 or less, and still more preferably 300 or more and 500 or less.

[0110] The cardanol compound may be used alone or in combination of two or more kinds.

[0111] Hereinafter, the fatty acid ester (B2) will be described. The fatty acid ester (B2) may be any of a monoester, a diester, a triester, and a polyester.

[0112] Examples of the fatty acid ester (B2) include aliphatic monocarboxylic acid esters (such as acetic acid esters), aliphatic dicarboxylic acid esters (such as succinic acid esters, adipic acid esters, azelaic acid esters, sebacic acid esters, stearic acid esters, etc.), aliphatic tricarboxylic acid esters (such as citric acid esters, isocitric acid esters, etc.), epoxidized fatty acid esters (such as epoxidized soybean oil, epoxidized linseed oil, epoxidized rapeseed fatty acid isobutyl, epoxidized fatty acid 2-ethylhexyl), fatty acid methyl esters, sucrose esters, and the like. The fatty acid ester may be acylated with an alkylcarboxylic acid anhydride (for example, a linear or branched alkylcarboxylic acid anhydride having 2 or more and 6 or less carbon atoms (preferably 2 or more and 3 or less carbon atoms) such as acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, etc.).

[0113] Preferred examples of the fatty acid ester (B2) include aliphatic dicarboxylic acid esters (especially adipic acid esters, sebacic acid), and aliphatic tricarboxylic acid esters (especially citric acid esters).

[0114] Specific examples of the adipic acid ester include adipic acid diesters represented by the following general formula (AE) and adipic acid polyesters represented by the following general formula (APE).

[0115]

Chemical formula

[0116] In general formula (AE), R AE1 and R AE2 each independently represents an alkyl group or a polyoxyalkyl group [-(C x H 2x -O) y -R A1 (wherein R A1 represents an alkyl group, x represents an integer of 1 or more and 10 or less, and y represents an integer of 1 or more and 10 or less).

[0117] In general formula (APE), R AE1 and R AE2 each independently represents an alkyl group or a polyoxyalkyl group [-(C x H 2x -O) y -R A1 (wherein R A1 represents an alkyl group, x represents an integer of 1 or more and 10 or less, and y represents an integer of 1 or more and 10 or less), and R AE3 represents an alkylene group. m1 represents an integer of 1 or more and 10 or less, and m2 represents an integer of 1 or more and 20 or less.

[0118] In general formulas (AE) and (APE), as the alkyl group represented by R AE1 and R AE2 , an alkyl group having 1 to 12 carbon atoms is preferable, an alkyl group having 4 to 10 carbon atoms is more preferable, and an alkyl group having 8 carbon atoms is still more preferable. The alkyl group represented by R AE1 and R AE2 may be linear, branched, or cyclic, and linear or branched is preferable.

[0119] In general formulas (AE) and (APE), in the polyoxyalkyl group [-(C AE1 H AE2 -O) x H 2x -O) y -R A1 represented by R A1 and R A1The alkyl group represented by [alkyl group] may be linear, branched, or cyclic, with linear or branched being preferred.

[0120] In the general formula (APE), R AE3 As the alkylene group represented by [alkylene group], an alkylene group having 1 to 6 carbon atoms is preferred, and an alkylene group having 1 to 4 carbon atoms is more preferred. The alkylene group may be linear, branched, or cyclic, with linear or branched being preferred.

[0121] In the general formula (APE), m1 is preferably an integer of 1 to 5, and m2 is preferably an integer of 1 to 10.

[0122] In the general formulas (AE) and (APE), the groups represented by each symbol may be substituted with substituents. Examples of the substituents include an alkyl group, an aryl group, a hydroxy group, and the like.

[0123] As the adipic acid ester, a mixture of an adipic acid ester and other components may be used. Commercially available products of such mixtures include Daifatty 101 manufactured by Daihachi Chemical Industry Co., Ltd.

[0124] Examples of the sebacic acid ester and the citric acid ester include alkyl esters of citric acid having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms).

[0125] Examples of the citric acid ester include alkyl esters of citric acid having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms). The citric acid ester may be a citric acid ester acylated with an alkyl carboxylic acid anhydride (for example, a linear or branched alkyl carboxylic acid anhydride having 2 to 6 carbon atoms (preferably 2 to 3 carbon atoms) such as acetic anhydride, propionic anhydride, butyric anhydride, and valeric anhydride).

[0126] The molecular weight (or weight-average molecular weight) of the fatty acid ester (B2) is preferably 200 or more and 2000 or less, more preferably 250 or more and 1500 or less, and still more preferably 280 or more and 1000 or less. Unless otherwise specified, the weight-average molecular weight of the ester compound is a value measured in accordance with the measurement method of the weight-average molecular weight of cellulose acylate.

[0127] The content of the aromatic compound, the fatty acid ester, or the total of the aromatic compound and the fatty acid ester is preferably 1% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 30% by mass or less, based on the cellulose resin.

[0128] The master particle may contain a resin other than the biodegradable resin. However, when other resins are included, the content of the other resins relative to the total amount of the resin composition is preferably 5% by mass or less, and preferably less than 1% by mass. It is more preferable not to contain other resins (that is, 0% by mass). Examples of other resins include conventionally known thermoplastic resins. Specifically, polycarbonate resin; polypropylene resin; polyester resin; polyolefin resin; polyester carbonate resin; polyphenylene ether resin; polyphenylene sulfide resin; polysulfone resin; polyether sulfone resin; polyarylene resin; polyetherimide resin; polyacetal resin; polyvinyl acetal resin; polyketone resin; polyether ketone resin; polyether ether ketone resin; polyaryl ketone resin; polyether nitrile resin; liquid crystal resin; polybenzimidazole resin; polyparabanic acid resin; vinyl polymers or copolymers obtained by polymerizing or copolymerizing one or more vinyl monomers selected from the group consisting of aromatic alkenyl compounds, methacrylic acid esters, acrylic acid esters, and vinyl cyanide compounds; diene-aromatic alkenyl compound copolymers; vinyl cyanide-diene-aromatic alkenyl compound copolymers; aromatic alkenyl compound-diene-vinyl cyanide-N-phenylmaleimide copolymers; vinyl cyanide-(ethylene-diene-propylene (EPDM))-aromatic alkenyl compound copolymers; vinyl chloride resins; chlorinated vinyl chloride resins; and the like. These resins may be used alone or in combination of two or more.

[0129] [First layer] The first layer is a resin layer on the surface of the mother particles. The first layer contains at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine.

[0130] The cationic resin may be any of polyalkyleneimine, polyallylamine, and polyvinylamine, but polyalkyleneimine is preferred from the viewpoints of improving the biodegradation rate over time and reducing the initial biodegradation rate.

[0131] As the polyalkyleneimine, from the viewpoints of improving the biodegradation rate over time and decreasing the initial biodegradation rate, polyalkyleneimine having a structural unit with an alkylene group having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms) is preferred, and polyethyleneimine is more preferred.

[0132] In particular, polyethyleneimine is a compound having high adhesiveness and high water absorbency. This is because the amino group of polyethyleneimine forms a hydrogen bond with a hydroxyl group, an ionic bond with a carboxyl group, and a covalent bond with a carbonyl group. Polyethyleneimine has a polar group (amino group) and a hydrophobic group (ethylene group) in its structure, so it has the property of easily binding different substances. Also, polyethyleneimine is a compound having high cationicity. Thereby, polyethyleneimine exists as a polycation under water and neutralizes and adsorbs anionic substances. Also, polyethyleneimine has a highly reactive primary amino group or secondary amino group, so it is a compound having high reactivity. Thereby, it easily reacts with various compounds. Therefore, when polyethyleneimine is applied as the polyalkyleneimine, the second layer containing a hydrophobic compound is more firmly coated on the mother particles, and while having a biodegradation rate over time, the initial biodegradation rate tends to be slow.

[0133] From the viewpoints of improving the biodegradation rate over time and decreasing the initial biodegradation rate, 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. The number average molecular weight of the cationic resin is measured in terms of polystyrene using a gel permeation chromatography apparatus (GPC apparatus: manufactured by Tosoh Corporation, HLC-8320GPC, column: TSKgel α-M) using tetrahydrofuran.

[0134] [Second Layer] The second layer is a compound layer provided on the first layer. The second layer contains an anionic or nonionic compound or a hydrophobic compound.

[0135] Examples of the anionic or nonionic compound or hydrophobic compound include hydrophobic compounds having an anionic group (-COOH (carboxyl group), -SO 3 H (sulfone group), etc.), hydrophobic compounds having no cationic group and anionic group. The hydrophobic compound refers to a compound that imparts hydrophobicity (specifically, water contact angle) to the biodegradable resin particles described later.

[0136] Examples of the hydrophobic compound include silicone compounds, hydrocarbon compounds, fatty acid compounds, acrylic resins, polyester resins, urethane resins, and the like. Among these, from the viewpoints of improving the biodegradation rate over time and decreasing the initial biodegradation rate, at least one selected from the group consisting of at least one selected from the group consisting of silicone compounds, hydrocarbon compounds, fatty acid compounds, acrylic resins, polyester resins, and urethane resins is preferable.

[0137] Examples of the silicone compound include dimethylpolysiloxane, methylpolysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, methylcyclopolysiloxane, 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, silicone rubber, and the like. Among these, as the silicone compound, from the viewpoints of improving the biodegradation rate over time and decreasing the initial biodegradation rate, at least one selected from the group consisting of dimethylpolysiloxane, methylpolysiloxane, MQ resin, and silicone rubber is preferable. Here, the MQ resin refers to a monofunctional siloxane unit [(CH 3 ) 3 SiO 1 / 2 of the M unit and the tetrafunctional siloxane unit [SiO4 / 2 It shows a silicone resin having a Q unit represented by ]].

[0138] Commercially available silicone compounds include silicone compounds 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 silicone compounds manufactured by Asahi Kasei Wacker Silicone Co., Ltd. (BELSIL DM3112VP)

[0139] Examples of hydrocarbon compounds include petroleum waxes (paraffin wax, microcrystalline wax, petrolatum wax, etc.), synthetic hydrocarbon waxes (polyethylene wax, polypropylene wax, polybutene wax, Fischer-Tropsch wax, etc.). Among these, from the viewpoints of improving the biodegradation rate over time and reducing the initial biodegradation rate, as the hydrocarbon compound, at least one selected from the group consisting of paraffin wax, microcrystalline wax, polyethylene wax, and polypropylene wax is preferable.

[0140] 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 Co., Ltd., polyethylene wax (AQUACER507, AQUACER840, AQUACER1547, AQUACER272, etc.) manufactured by BYK Co., Ltd., polyethylene wax (Hi-Tech E-2213, Hi-Tech E-6324, etc.) manufactured by Toho Chemical Co., Ltd., polypropylene wax (AQUACER593, etc.) manufactured by BYK Co., Ltd., polypropylene (Hi-Tech P-9018, Hi-Tech P-5060P, etc.) manufactured by Toho Chemical Co., Ltd., etc.

[0141] Examples of the fatty acid compound 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, palm oil, walnut oil, olive oil, peanut oil, almond oil, jojoba oil, cocoa butter, shea butter, neem oil, safflower oil, candelilla wax, rice wax, carnauba wax, etc.). Among these, from the viewpoints of improving the biodegradation rate over time and reducing the initial biodegradation rate, at least one selected from the group consisting of carnauba wax, rice wax, candelilla wax, palm wax, castor oil wax, soybean oil wax, and sunflower oil wax is preferable.

[0142] Examples of commercially available products of the fatty acid compound include carnauba wax (EMUSTAR-0413 (carnauba wax)) manufactured by Nippon Seiro Co., Ltd., rice 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., palm oil wax (Kakko Ace TKE, etc.) manufactured by Nippon Seiro Co., Ltd., etc.

[0143] Examples of the acrylic resin include well-known acrylic resins such as polymers of acrylic acid and polymers of alkyl acrylates. Examples of commercially available products of the acrylic resin include, for example, acrylic resins (3WX-2015, 3MF-320, 3MF-333, 3MF-407, etc.) manufactured by Daisheng Fine Co., Ltd., and acrylic resins (Coat SFC-6440, Boncoat CE-6270, Boncoat CE-6400, Boncoat CF-2800, etc.) manufactured by DIC Corporation.

[0144] Examples of the polyester resin include well-known polyester resins such as polycondensates of polyhydric alcohols and polyhydric alcohols, and ring-opening polycondensates of cyclic lactams. Examples of commercially available polyester resins include, for example, polyester resins (A-110F, A-160P, A-520, A-613D, A-615GE, A-640, A-645GH, A-647GEX, etc.) manufactured by Takamatsu Yushi Co., Ltd.

[0145] Examples of the urethane resin include well-known urethane resins such as polyester-based polyurethanes, polyether-based polyurethanes, and polycarbonate-based polyurethanes. Further, as the urethane resin, a material having a urethane polymer shell layer around the core of an acrylic polymer may be used. Examples of commercially available urethane resins include, for example, urethane resins (WEM-031U, WEM-200U, WEM-321U, WEM-3000, WBR-016U, WBR-2101, etc.) manufactured by Daisheng Fine Co., Ltd.

[0146] [Content of each layer] In the biodegradable resin particles according to the present embodiment, from the viewpoints of improving the biodegradation rate over time and reducing the initial biodegradation rate, the mass ratio (coating amount of cationic resin / coating amount of hydrophobic compound) of the coating amount of the cationic resin in the first layer to the coating amount of the hydrophobic compound in the second layer 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.

[0147] Further, from the viewpoints of improving the biodegradation rate over time and reducing the initial biodegradation rate, the content of the cationic resin with respect to the mother particles is preferably 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. Further, from the viewpoints of improving the biodegradation rate over time and reducing the initial biodegradation rate, the content of the hydrophobic compound with respect to the mother particles is preferably 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.

[0148] Here, the coating amounts of the cationic resin and the hydrophobic compound (i.e., the coating amounts of the first layer and the second layer) are measured as follows. The coating amount of the cationic resin is determined by the difference between the treatment amount of the cationic resin and the cationic resin obtained by drying the supernatant after treatment. Similarly, the coating amount of the hydrophobic compound is determined by the difference between the treatment amount of the hydrophobic compound and the hydrophobic compound obtained by drying the supernatant after treatment.

[0149] [Properties of Biodegradable Resin Particles] In the biodegradable resin particles according to this embodiment, the water contact angle when the biodegradable resin particles are pelletized is 70° or more and 120° or less. When the contact angle is within the above range, the initial biodegradation rate decreases. The water contact angle is preferably 72° or more and 110° or less, more preferably 75° or more and 105° or less.

[0150] The water contact angle is measured after pelletizing the prepared biodegradable particles. In an environment of 23°C, using a contact angle meter (model number: CA-X type manufactured by Kyowa Interface Science Co., Ltd.), drop 1 μl of water droplets onto the surface of the pellet with a syringe and measure after 1 minute.

[0151] The biodegradable resin particles according to this embodiment have an aerobic biodegradation rate after 3 months of 20% or less as measured by a method according to ISO-14855-2 (2018). When the aerobic biodegradation rate after 3 months is within the above range, the initial biodegradation rate decreases. The aerobic biodegradation rate after 3 months is preferably 15% or less, more preferably 10% or less, still more preferably 5% or less. The lower limit is ideally 0%, but for example, it is 1% or more.

[0152] For the biodegradable resin particles according to this embodiment, the ratio of the aerobic biodegradation rate after 6 months to the aerobic biodegradation rate after 3 months (aerobic biodegradation rate after 6 months / aerobic biodegradation rate after 3 months) as measured by a method according to ISO-14855-2 (2018) is preferably 1.20 or more, preferably 1.50 or more, and more preferably 2.00 or more. Also, the ratio of the aerobic biodegradation rate after 12 months to the aerobic biodegradation rate after 3 months (aerobic biodegradation rate after 12 months / aerobic biodegradation rate after 3 months), measured by a method according to ISO - 14855 - 2 (2018), is preferably 3.50 or more, preferably 5.00 or more, more preferably 10.00 or more, still more preferably 15.00 or more, and even more preferably 20.00 or more.

[0153] In the biodegradable resin particles according to this embodiment, when the surface of the biodegradable resin particles is measured by X - ray photoelectron spectroscopy (XPS), the relationship between the carbon atomic weight Cs, the silicon atomic weight Sis, and the oxygen atomic weight Os satisfies the formula A: (Cs + Sis) / Os ≥ 3. When the formula A is satisfied, the initial biodegradation rate decreases. Also, the lipophilicity of the surface of the biodegradable resin particles is improved, and the oil absorption rate of the resin particles increases. From the viewpoints of reducing the initial biodegradation rate and improving the oil absorption rate, the value of "(Cs + Sis) / Os" is preferably 4 or more, and more preferably 7 or more. However, the upper limit of the value of "(Cs + Sis) / Os" is, for example, 95 or less from the viewpoint of the biodegradation rate over time. In order to make the value of "(Cs + Sis) / Os" within the above range, it is preferable to coat the mother particles with a second layer containing a hydrophobic compound.

[0154] In the biodegradable resin particles according to this embodiment, when the surface of the biodegradable resin particles after 3 minutes of surface etching is measured by X - ray photoelectron spectroscopy (XPS), the relationship between the carbon atomic weight Ce, the silicon atomic weight Sie, and the oxygen atomic weight Oe preferably satisfies the formula B: (Ce + Sie) / Oe ≥ 3. When the formula B is satisfied, the period during which the biodegradation rate is decreased becomes longer. Also, it becomes easier to maintain a high oil absorption rate. Furthermore, even when a mechanical load is applied to the biodegradable resin particles (for example, when the biodegradable resin particles are stirred by ultrasonic homogenization, etc.), the oil absorption rate is less likely to decrease. The value of "(Ce + Sie) / Oe" is more preferably 4 or more, and even more preferably 7 or more, from the viewpoints of maintaining the initial biodegradation rate and the oil absorption rate. However, the upper limit of the value of "(Ce + Sie) / Oe" is, for example, 95 or less from the viewpoint of the biodegradation rate over time. In order to make the value of "(Ce + Sie) / Oe" within the above range, it is preferable to sequentially coat the mother particles with a first layer containing a cationic resin and a second layer containing a hydrophobic compound.

[0155] Here, the method for measuring each atomic weight (atom%) by X-ray photoelectron spectroscopy (XPS) is as follows. The measurement is performed on the prepared biodegradable particles. Using "PHI5000 Versa Probe II manufactured by ULVAC-PHI" as the XPS measurement device, using monochromatized AlKα rays as the X-ray source, and setting the acceleration voltage to 15 kV to perform the measurement. Specifically, with an analysis area of 100 μmφ, based on the spectra of each atom (carbon atom, silicon atom, and oxygen atom) measured, the number of each atom (carbon atom, silicon atom, and oxygen atom) is determined, and the atomic weight of each atom (carbon atomic weight, silicon atomic weight, and oxygen atomic weight) with respect to the total atomic weight in the measurement area is calculated.

[0156] Then, when measuring the surface of the biodegradable resin particles before etching, the carbon atomic weight, silicon atomic weight, and oxygen atomic weight are determined as the carbon atomic weight Cs, silicon atomic weight Sis, and oxygen atomic weight Os. Also, when measuring the surface of the biodegradable resin particles after performing surface etching for 3 minutes, the carbon atomic weight, silicon atomic weight, and oxygen atomic weight are determined as the carbon atomic weight Ce, silicon atomic weight Sie, and oxygen atomic weight Oe. However, when the compound contained in the second layer does not contain a silicon atom, the silicon atomic weight becomes 0 atom%.

[0157] Note that the surface etching is performed on the prepared biodegradable particles as follows. As an etching device, "PHI5000 Versa Probe II manufactured by ULVAC-PHI, Inc." was used, and argon gas cluster etching was performed for 3 minutes under the conditions of an acceleration voltage of 5 kV and a scanning area of 2 mm × 2 mm using argon as the etching gas.

[0158] The volume average particle diameter 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. When the particle diameter of the granular material is 3 μm or more, the number of particles per unit weight does not become too large, so a decrease in the biodegradation rate is suppressed. On the other hand, when the particle diameter of the biodegradable resin particles is 100 μm or less, the specific surface area increases, and the biodegradation rate can be further improved. Therefore, the volume average particle diameter of the granular material is preferably in the above range.

[0159] The large-diameter side particle size distribution index GSDv of the biodegradable resin particles is preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.2 or less. When the particle size distribution of the biodegradable resin particles approaches uniformity, regular hydrolysis proceeds by providing a certain contact opportunity with water, and the biodegradation rate can be further improved.

[0160] The volume average particle diameter and the large-diameter side particle size distribution index GSDp of the biodegradable resin particles are measured as follows. The particle diameter is measured using an LS particle size distribution measuring device "Beckman Coulter LS13 320 (manufactured by Beckman Coulter, Inc.)", and the cumulative distribution of the particle diameter is drawn from the small-diameter side on a volume basis, and the particle diameter at which the cumulative value reaches 50% is determined as the volume average particle diameter. On the other hand, the cumulative distribution of the particle diameter is drawn from the small-diameter side on a volume basis, and the particle diameter at which the cumulative value reaches 50% is defined as the number average particle diameter D50v, and the particle diameter at which the cumulative value reaches 84% is defined as the number particle diameter D84v. Then, the large-diameter side number particle size distribution index GSDv is calculated by the formula GSDv = (D84v / D50v) 1 / 2 is calculated.

[0161] [Method for producing biodegradable resin particles] As a method for producing the biodegradable resin particles according to the present embodiment, for example, a first step of mixing an aqueous dispersion in which mother particles are dispersed and an aqueous solution containing a cationic resin; a second step of taking out the mother particles from the mixed solution to obtain an aqueous dispersion in which the mother particles are dispersed, mixing the aqueous dispersion with an emulsion solution of an anionic or nonionic hydrophobic compound, and then drying; A method having the above is exemplified.

[0162] Hereinafter, it will be specifically described.

[0163] - First step - In the first step, mother particles are prepared. Examples of the method for producing the mother particles include the following methods. 1) A kneading and pulverizing method in which each component is kneaded, and the obtained kneaded product is pulverized and classified to obtain granular materials; 2) A dry method in which the granular materials obtained by the kneading and pulverizing method are changed in shape by mechanical impact force or thermal energy to obtain granular materials; 3) An aggregation and integration method in which particle dispersions of each component are mixed, and the particles in the dispersion are aggregated and heat-fused to obtain granular materials; 4) A dissolution and suspension method in which an organic solvent in which each component is dissolved is suspended in an aqueous solvent to granulate granular materials containing each component.

[0164] Among these, from the viewpoint of obtaining biodegradable resin particles having a volume average particle diameter and a large-diameter side particle size distribution index GSDv described later, wet methods such as the aggregation and integration method and the dissolution and suspension method are preferable.

[0165] Next, an aqueous dispersion in which the obtained mother particles are dispersed is prepared. Before preparing the aqueous dispersion, it is preferable to wash the mother particles with an acid.

[0166] Next, the aqueous dispersion and the aqueous dispersion in which the mother particles are dispersed and an aqueous solution containing a cationic resin are mixed. Thereby, for example, the hydroxyl group of the resin contained in the mother particles reacts with the amine site of the cationic resin, and the first layer is formed.

[0167] - Second step - In the second step, the mother particles with the first layer formed are taken out from the mixed solution. The mother particles are taken out, for example, by filtering the mixed solution. The taken-out mother particles are preferably washed with water. Thereby, unreacted cationic resin can be removed.

[0168] Next, after preparing an aqueous dispersion in which the mother particles are dispersed, the aqueous dispersion and an emulsion solution of an anionic or nonionic hydrophobic compound are mixed. Thereby, the emulsion of the hydrophobic compound is adsorbed onto the first layer of the mother particles. After that, when the mixed solution is dried, the emulsion of the hydrophobic compound breaks, and the hydrophobic compound forms a film on the first layer. Thereby, the second layer is formed.

[0169] Through the above steps, the biodegradable resin particles according to this embodiment are obtained.

[0170] As uses of the biodegradable resin particles according to this embodiment, there are mentioned cosmetic base materials, rolling agents, abrasives, scrubbing agents, display spacers, bead molding materials, light diffusing particles, resin strengthening agents, refractive index controlling agents, biodegradation accelerators, fertilizers, water-absorbing particles, and granular toner particles.

Examples

[0171] Examples are given below to more specifically explain the resin composition and resin molded article according to this embodiment. The materials, amounts used, ratios, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the resin composition and resin molded article according to this embodiment should not be construed in a limited manner by the specific examples shown below.

[0172] <Preparation of Each Material> The following materials were prepared.

[0173] [Biodegradable Resin of Mother Particles] · DAC: "L-50" manufactured by Daicel Corporation, cellulose diacetate, weight average degree of polymerization 570 · CAB: Eastman Chemical "CAP504-0.2", cellulose acetate propionate, weight average degree of polymerization 133, degree of acetyl substitution 0.04, degree of propionyl substitution 2.09 · CAP: cellulose acetate propionate, weight average degree of polymerization 716, degree of acetyl substitution 0.18, degree of propionyl substitution 2.49 · PLA: polylactic acid, weight average molecular weight 180000 · PHA: polyhydroxyalkanoic acid · PBS: polybutylene succinate, weight average molecular weight 200000 · PBSA: polybutylene succinate adipate, weight average molecular weight 110000 · PBAT: polybutylene adipate terephthalate, weight average molecular weight 100000 · PETS: polyethylene terephthalate / succinate copolymer, weight average molecular weight 150000

[0174] [Plasticizer for masterbatch] · CDNl: Cardolite "NX-2503", hydroxyethylated cardanol, molecular weight 296 - 320 · CDN2: Cardolite "Ultra LITE 513", glycidyl ether of cardanol, molecular weight 354 - 361. · CDN3: Alkyl-modified product of DIC's "EPICLON865 - alkyl-modified product", alkyl-modified product of phenol novolak type epoxy resin · DBA: Diisobutyl adipate · ATBC: Triethyl O-acetylcitrate · DPS: Diisopropyl sebacate

[0175] [Cationic resin for the first layer] · PEI: Polyethyleneimine, the number average molecular weight Mn of the material used is shown in Table 1. · PAA: Polyallylamine, the number average molecular weight Mn of the material used is shown in Table 1. · PVAM: Polyvinylamine, the number average molecular weight Mn of the material used is shown in Table 1.

[0176] [Second layer, anionic or cationic hydrophobic compound] ·EMUSTAR-0135: Paraffin wax manufactured by Nippon Seiro Co., Ltd. ·POLON-MN-ST: Dimethyl silicone manufactured by Shin-Etsu Chemical Co., Ltd. ·KM-9717: MQ resin manufactured by Shin-Etsu Chemical Co., Ltd. ·BELSIL DM3112VP: Dimethicone (dimethyl silicone) manufactured by Asahi Kasei Wacker Silicone Co., Ltd. ·Hi-Tech E-2213: Polyethylene wax manufactured by Toho Chemical Industry Co., Ltd. ·Hi-Tech P-9018: Polypropylene wax manufactured by Toho Chemical Industry Co., Ltd. ·EMUSTAR-0413: Carnauba wax manufactured by Nippon Seiro Co., Ltd. ·3MF-320: Acrylic resin manufactured by Daisheng Fine Co., Ltd. ·A-647GEX: Polyester resin manufactured by Takamatsu Yushi Co., Ltd. ·WBR-016U: Urethane resin manufactured by Daisheng Fine Co., Ltd.

[0177] [Examples A1 to A30, B1 to B29, Comparative Examples A1 to A2, B1 to B2] (Preparation of resin pellets) The cylinder temperature was adjusted according to the charging composition ratios shown in Tables 1 to 2, and kneading was carried out using a twin-screw kneading apparatus (TEX41SS, manufactured by Toshiba Machine Co., Ltd.) to obtain a resin composition in pellet form (hereinafter referred to as resin pellets).

[0178] (Preparation of masterbatch) When DAC, CAB, and CAP were used as resins, masterbatch was obtained as follows. 300 g of resin pellets were completely dissolved in 700 g of methyl ethyl ketone. This was added to an aqueous liquid in which 100 g of calcium carbonate, 4 g of carboxymethyl cellulose, and 200 g of methyl ethyl ketone were dispersed in 1100 g of pure water, and stirred for 3 hours. 10 g of sodium hydroxide was added thereto, heated to 80 °C, and stirred for 3 hours to remove methyl ethyl ketone. After filtering the residue, it was dispersed again in pure water to obtain a slurry of masterbatch.

[0179] On the other hand, when using a resin other than DAC, CAB, and CAP as the resin, master particles were obtained as follows. 2000 g of resin pellets were melt-kneaded (in a kneader), the kneaded product was rolled with two rolls to form a plate shape, and after the formed product was cooled, it was roughly pulverized with a pulverizer. The master particles were obtained by finely pulverizing this roughly pulverized product with a jet mill. The master particles were dispersed in pure water to obtain a slurry of the master particles.

[0180] (Preparation of biodegradable resin particles) Using the materials for the first layer and the second layer shown in Tables 1 to 2, biodegradable resin particles were obtained as follows so that the coating amounts of each layer were the amounts shown in Tables 1 to 2. After adjusting the slurry of the master particles so that the solid content became 20%, a predetermined amount of a solution of a cationic resin was added in terms of pure content to the solid content contained in this slurry, and the mixture was stirred at 25 °C for 1 hour. After completion of the stirring, the residue was filtered, redispersed in pure water, adjusted so that the solid content became 20%, and a predetermined amount of a hydrophobic compound was added in terms of pure content to the solid content contained in this slurry, and the mixture was stirred at 25 °C for 1 hour. After completion of the stirring, the residue was filtered, and the solid content was freeze-dried to obtain biodegradable resin particles. Through the above steps, biodegradable resin particles were obtained. In Comparative Examples A2 and B2, the first layer was not formed, and a treatment (addition treatment of a hydrophobic compound) for forming the second layer so as to have the same coating amount as in Examples A1 and B1 was carried out. However, the hydrophobic compound was difficult to adsorb, and the coating amount of the second layer was 0.0001%.

[0181] <Properties of biodegradable resin particles> According to the described method, the properties of the following biodegradable resin particles were measured. The results are shown in Tables 1 to 2. · Water contact angle (denoted as "contact angle" in the table) · Volume average particle diameter D50v · (Cs + Sis) / Os value (denoted as "(C + Si) / O ratio T = 0" in the table) · (Ce + Sie) / Oe value (denoted as "(C + Si) / O ratio T = 3" in the table)

[0182] <Hydrolysis resistance> The hydrolysis resistance of the biodegradable resin particles was evaluated as follows. However, the evaluation of hydrolysis was carried out only on the biodegradable resin particles of Examples B1 to B29 and Comparative Examples B1 to B2. 50 g of the biodegradable resin particles were enclosed in a bag made of #508 / 585-1μm nylon mesh (mesh opening 1μm) and immersed in distilled water adjusted to 50°C and pH 7.8 for 90 days. Then, the nylon mesh containing the resin particles was taken out, and the resin particles in the nylon mesh were vacuum dried. The mass of the biodegradable resin particles after vacuum drying was measured, and the mass reduction rate of the biodegradable resin particles was measured. And it was evaluated according to the following criteria. A: The mass reduction rate is 0% or more and less than 10% B: The mass reduction rate is 10% or more and less than 20% C: The mass reduction rate is 20% or more and less than 30% D: The mass reduction rate is 30% or more

[0183] <Oil absorption> -Initial oil absorption rate- After dispersing 1 g of the biodegradable resin particles in 10 g of linseed oil, centrifugation was performed at 10,000 rpm for 20 minutes. After gently removing the supernatant, the mass of the biodegradable resin particles was measured. And the oil absorption rate was calculated by the following formula. ·Formula: Oil absorption rate = (Increase in mass after centrifugation / Mass before dispersion in linseed oil) × 100

[0184] -Oil absorption rate after stirring- An ultrasonic homogenizer was installed in a solution of 1 g of the biodegradable resin particles dispersed in 10 g of linseed oil, irradiated with ultrasonic waves of 20 kHz, and the solution was stirred for 10 minutes. After centrifuging the stirred solution at 10,000 rpm for 20 minutes and gently removing the supernatant, the mass of the biodegradable resin particles was measured. And the oil absorption rate was calculated by the above formula.

[0185] In addition, the oil absorption rate was evaluated according to the following criteria. (A): 110% or more (B): 90% or more and 109% or less (C): 70% or more and 89% or less (D): 69% or less

[0186] <Measurement of biodegradability> Using the obtained biodegradable resin particles, the aerobic biodegradation rates after 3 months, 6 months, and 12 months were measured by a method in accordance with ISO-14855-2 (2018). The results are shown in Tables 1 to 2.

[0187]

Table 1-1

[0188]

Table 1-2

[0189]

Table 2-1

[0190]

Table 2-2

[0191] From the above results, it can be seen that the biodegradable resin particles of this example have a biodegradation rate over time and a slow initial biodegradation rate compared to the biodegradable resin particles of the comparative example. Also, it can be seen that the biodegradable resin particles of this example have a higher oil absorption rate compared to the biodegradable resin particles of the comparative example. In addition, in the biodegradable resin particles of this example, the biodegradable resin particles obtained by sequentially coating a mother particle obtained by adding a specific plasticizer to a cellulose resin as the biodegradable resin with a first layer containing a cationic resin and a second layer containing a hydrophobic compound are found to have biodegradability and excellent hydrolysis resistance.

Claims

1. Master particles containing a biodegradable resin, A first layer containing at least one cationic resin of polyalkyleneimine, polyallylamine, and polyvinylamine, which is present on the surface of the master particles, A second layer containing an anionic or nonionic hydrophobic compound, which is present on the first layer, Biodegradable resin particles having the above.

2. The biodegradable resin particles according to Claim 1, wherein the hydrophobic compound is at least one selected from the group consisting of silicone compounds, hydrocarbon compounds, fatty acid compounds, acrylic resins, polyester resins, and urethane resins.

3. The biodegradable resin particles according to Claim 2, wherein the silicone compound is at least one selected from the group consisting of dimethylpolysiloxane, methylpolysiloxane, MQ resin, and silicone rubber.

4. The biodegradable resin particles according to Claim 2 or Claim 3, wherein the hydrocarbon compound is at least one selected from the group consisting of paraffin wax, microcrystalline wax, polyethylene wax, and polypropylene wax.

5. The biodegradable resin particles according to any one of Claims 2 to 4, wherein the fatty acid compound is at least one selected from the group consisting of carnauba wax, rice wax, candelilla wax, palm wax, castor oil wax, soybean oil wax, and sunflower oil wax.

6. The biodegradable resin particles according to any one of Claims 1 to 5, wherein the polyalkyleneimine is a polyalkyleneimine having a structural unit having an alkylene group having 1 to 4 carbon atoms.

7. The biodegradable resin particles according to Claim 6, wherein the polyalkyleneimine having a structural unit having an alkylene group having 1 to 4 carbon atoms is polyethyleneimine.

8. The biodegradable resin particles according to any one of Claims 1 to 7, wherein the biodegradable resin is at least one selected from the group consisting of cellulose resins and polyester resins.

9. The biodegradable resin particles according to Claim 8, wherein the biodegradable resin is a cellulose resin.

10. The biodegradable resin particles according to Claim 9, wherein the cellulose resin is cellulose acylate having two or more acyl groups.

11. An aromatic compound that does not have a functional group reactive with the cellulose resin and has at least one of a phenolic hydroxyl group and a monoglycidyl ether group directly bonded to an aromatic group together with a long-chain aliphatic group, and at least one kind of fatty acid ester, the biodegradable resin particles according to claim 9 or claim 10.

12. The biodegradable resin particles according to claim 11, wherein the aromatic compound is a cardanol compound.

13. The biodegradable resin particles according to claim 12, wherein the cardanol compound is at least one compound selected from the group consisting of a compound represented by the following general formula (CDN1) and a compound represented by the following general formula (CDN1-e). 【Chemical 1】 (In the general formula (CDN1), R １ represents an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. R ２ represents a hydroxy group, a carboxy group, an alkyl group which may have a substituent, or an unsaturated aliphatic group which has a double bond and may have a substituent. P2 represents an integer of 0 or more and 4 or less. When P2 is 2 or more and a plurality of R ２ are present, they may be the same group or different groups.) 【Chemical Formula 2】 (In the general formula (CDN1-e), L ＥＰ represents a single bond or a divalent linking group. In the general formula (CDN1-e), R １ , R ２ and P2 each have the same meaning as R １ , R ２ and P2 in the general formula (CDN1).)

14. The biodegradable resin particles according to any one of claims 11 to 13, wherein the mother particles contain cellulose acetate propionate as the cellulose resin and a cardanol compound as the aromatic compound.

15. The biodegradable resin particles according to any one of claims 11 to 13, wherein the mother particles contain cellulose acetate butyrate as the cellulose resin and the fatty acid ester.

16. The biodegradable resin particles according to any one of claims 1 to 15, wherein the mass ratio of the coating amount of the cationic resin to the coating amount of the hydrophobic compound (coating amount of the cationic resin / coating amount of the hydrophobic compound) is 0.1 or more and 10 or less.

17. The biodegradable resin particles according to claim 16, wherein the coating amount of the cationic resin with respect to the mother particles is 0.1% by mass or more and 10% by mass or less.

18. The biodegradable resin particles according to any one of claims 1 to 17, wherein the number average molecular weight of the cationic resin is 10,000 or more and 85,000 or less.

Images