Polymer particles and method for producing the same, and method for producing molded article

Abstract

To provide a molded article with improved durability characteristics including toughness, heat resistance, oil resistance, and water resistance through production and molding of polymer particles having a large molecular weight.SOLUTION: A method for producing polymer particles, comprising suspending an oil phase containing a polymerizable monomer and a polymerization initiator in an aqueous phase to induce suspension polymerization, wherein the aqueous phase comprises at least one selected from the group consisting of phosphorus oxoacids and salts thereof, alkali metal iodides, alkali metal fluorides, and quaternary ammonium salts, and the polymerization initiator is an organic boron compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to polymer particles, a method for producing the same, and a method for producing a molded article. [Background technology]

[0002] Polymers using (meth)acrylates, styrene, etc. are expected to be used as implant materials because they are relatively gentle on the human body. However, molded articles using these polymers inherently lack toughness and are prone to durability problems. Therefore, Patent Document 1 proposes that an elastomeric polymer be added to improve toughness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-59094 Summary of the Invention [Problem to be solved by the invention]

[0004] However, although blending an elastomer as in Patent Document 1 improves flexibility, it also reduces mechanical strength. Therefore, for applications that also require mechanical strength, such as artificial joints (including bone cement for artificial joint fixation), artificial bones, interbody fusion devices (materials) such as interbody cages, bone spacers such as cervical spacers, and internal fixation devices (materials) used to fix fractures (including osteotomy), such as pedicle screws, there is a demand for polymers that can produce molded articles with excellent durability without relying on elastomers.

[0005] Generally, the larger the molecular weight of a polymer, the easier it is to obtain a molded article having improved durability properties such as toughness, heat resistance, oil resistance, and water resistance. In view of the above circumstances, an object of the present invention is to provide polymer particles having a high molecular weight, and to provide a molded article having improved durability properties such as toughness, heat resistance, oil resistance, and water resistance by molding the high molecular weight polymer particles. [Means for solving the problem]

[0006] The present invention employs the following configuration. [1] A method for producing polymer particles by suspending an oil phase containing a polymerizable monomer and a polymerization initiator in an aqueous phase and carrying out suspension polymerization, the aqueous phase contains one or more selected from the group consisting of phosphorus oxoacids and salts thereof, alkali metal iodides, alkali metal fluorides, and quaternary ammonium salts; The method for producing polymer particles, wherein the polymerization initiator is an organic boron compound. [2] The method for producing polymer particles according to [1], wherein the amount of the polymerization initiator is 1.0 to 15.0 parts by mass per 100 parts by mass of the polymerizable monomer. [3] The method for producing polymer particles according to [1] or [2], wherein the polymerizable monomer is at least one selected from the group consisting of (meth)acrylates and styrenes. [4] A method for producing a molded article, comprising obtaining polymer particles by the method for producing polymer particles according to any one of [1] to [3] and molding the obtained polymer particles. [5] The method for producing a molded article according to [4], wherein the molded article is a bioimplant material. [6] Polymer particles having a boron element content of 0.01% by mass or more and 0.30% by mass or less, based on the total mass of the polymer particles. [7] The polymer particles according to [6], wherein the polymer particles have units derived from one or more polymerizable monomers selected from the group consisting of (meth)acrylates and styrenes. [8] The polymer particles according to [7], wherein the polymer particles are mainly composed of units derived from methyl methacrylate and have a weight average molecular weight (Mw) of 250,000 or more. [9] The polymer particles according to [7], wherein the polymer particles are mainly composed of units derived from methyl acrylate and have a weight average molecular weight (Mw) of 1,200,000 or more.

[10] The polymer particles according to [7], wherein the polymer particles are mainly composed of units derived from butyl methacrylate and have a weight average molecular weight (Mw) of 140,000 or more.

[11] The polymer particles according to [7], wherein the polymer particles are mainly composed of units derived from methyl (meth)acrylate and styrene, and have a weight average molecular weight (Mw) of 300,000 or more.

[12] The polymer particles according to [7], wherein the polymer particles are mainly composed of units derived from styrene and have a weight average molecular weight (Mw) of 150,000 or more. [Effects of the Invention]

[0007] The polymer particles obtained by the production method of the present invention and the polymer particles of the present invention have a high molecular weight. Furthermore, according to the method for producing a molded article of the present invention, it is easy to obtain a molded article having excellent durability properties such as toughness, heat resistance, oil resistance, and water resistance. DETAILED DESCRIPTION OF THE INVENTION

[0008] In this specification and claims, the term "unit" refers to a moiety derived from a monomer that exists in a polymer and constitutes the polymer. Additionally, "(meth)acrylate" is a general term for acrylate and methacrylate. Furthermore, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid, and for example, "methyl (meth)acrylate" is a general term for methyl acrylate (methyl acrylate) and methyl methacrylate (methyl methacrylate). Furthermore, the phrase "mainly composed of" a unit derived from a certain monomer means that the proportion of the unit in question to all units is 90% by mass or more.

[0009] <Method of producing polymer particles> A method for producing polymer particles according to one embodiment of the present invention is a method for producing polymer particles in which an oil phase containing a polymerizable monomer and a polymerization initiator is suspended in an aqueous phase and subjected to suspension polymerization. In this embodiment, the aqueous phase contains one or more dispersants selected from the group consisting of phosphorus oxoacids and their salts, alkali metal iodides, alkali metal fluorides, and quaternary ammonium salts (hereinafter, these may be collectively referred to as "specific dispersants"). The polymerization initiator in this embodiment is an organoboron compound.

[0010] [Polymerizable monomer] There are no particular limitations on the polymerizable monomer used in this embodiment, but from the viewpoint of reducing the biotoxicity of the polymer particles obtained by polymerization, it is preferable to use one or more types selected from the group consisting of (meth)acrylates and styrenes. As the (meth)acrylate, either a monofunctional monomer or a polyfunctional monomer can be used depending on the purpose of use.

[0011] The monofunctional (meth)acrylate is preferably a monomer represented by the following general formula (1).

[0012] [ka]

[0013] In formula (1), R 1 is a hydrogen atom or a methyl group. In formula (1), R 2 is a linear, branched or cyclic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent.

[0014] R 2Examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, an n-pentyl group, a 1-ethylpropyl group, an isopentyl group, a sec-pentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, a 1,1-diethylpropyl group, an n-hexyl group, an isohexyl group, a tert-hexyl group, a cyclohexyl group, a 2-ethyl ... alkyl groups such as xyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and adamantan-1-yl groups; aryl groups such as phenyl; arylalkyl groups such as benzyl; alkenyl groups such as vinyl, allyl, 3-butenyl, and 3-methyl-3-butenyl groups; and alkynyl groups such as propargyl.

[0015] R 2 Of the above, the hydrocarbon group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate, with methyl (meth)acrylate and ethyl (meth)acrylate being preferred.

[0016] R 2 The substituent that may be possessed by may be, for example, a halogen atom. R having a halogen atom as a substituent 2 is a perfluorooctyl group, a hexafluorobutyl group, or the like.

[0017] R 2 An example of the substituent that may be present is a hydroxy group. R having a hydroxy group as a substituent 2Examples of the alkyl group include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxy-1-methylethyl group, a 2-hydroxy-1-methylethyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, a 4-hydroxybutyl group, a 5-hydroxypentyl group, a 6-hydroxyhexyl group, a 1,2-dihydroxypropyl group, and a 1,3-dihydroxypropyl group.

[0018] Further examples of monofunctional (meth)acrylates other than the monomer represented by general formula (1) include silane compounds having a (meth)acryloxyalkyl group, such as γ-(meth)acryloxypropyltrimethoxysilane and γ-(meth)acryloxypropyltri(trimethylsiloxy)silane; (meth)acrylates having a heterocycle, such as tetrahydrofurfuryl (meth)acrylate; and metal (meth)acrylates, such as zinc (meth)acrylate, potassium (meth)acrylate, magnesium (meth)acrylate, and calcium (meth)acrylate.

[0019] As the monofunctional (meth)acrylate, a monomer represented by the following general formula (2) having an alkylene glycol chain in its molecular structure may be used.

[0020] [ka]

[0021] In formula (2), R 1 is R in the formula (1) 1 is a hydrogen atom or a methyl group, and R 3 represents an alkylene group having 1 to 4 carbon atoms, and R 4 represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and n represents a number from 1 to 100. When n is 2 or more, multiple R 3 may be the same or different from each other.

[0022] R 3Examples of the alkylene group having 1 to 4 carbon atoms include a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, and an isobutylene group, and an ethylene group is preferred.

[0023] R 4 Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-dodecyl group (an n-lauryl group), an n-undecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, an eicosyl group, an ethyl ... Examples of suitable alkyl groups include alkyl groups such as cyclohexyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, and triacontyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl; arylalkyl groups such as benzyl and nonylphenyl; alkenyl groups such as vinyl, allyl, 3-butenyl, and 3-methyl-3-butenyl; and alkynyl groups such as propargyl. The alkyl group may be a linear or branched alkyl group. As the hydrocarbon group, an alkyl group having 1 to 18 carbon atoms is preferred, an alkyl group having 1 to 12 carbon atoms is more preferred, and an alkyl group having 1 to 3 carbon atoms is even more preferred.

[0024] n represents a number from 1 to 100. n is "-(R 3 n is the average number of "-O)-" groups. n may be appropriately set depending on the application. For example, when polymer particles obtained by the polymerization reaction are molded and used as an implant material, n is preferably 1 to 20, more preferably 1 to 10. The value of n can be, for example, 1 It can be measured by 1 H NMR (nuclear magnetic resonance) method.

[0025] Specific examples of the monomer represented by general formula (2) being a (poly)alkylene glycol mono(meth)acrylate include (poly)methylene glycol mono(meth)acrylates such as (poly)methylene glycol mono(meth)acrylate, (poly)methylene glycol mono(meth)acrylate, (poly)methylene glycol mono(meth)acrylate, and (poly)methylene glycol mono(meth)acrylate; (Poly)ethylene glycol mono(meth)acrylates such as (poly)ethylene glycol mono(meth)acrylate, (poly)ethylene glycol mono(meth)acrylate, (poly)ethylene glycol mono(meth)acrylate, (poly)ethylene glycol mono(meth)acrylate; (poly)propylene glycol mono(meth)acrylates such as (poly)propylene glycol mono(meth)acrylate, (poly)propylene glycol mono(meth)acrylate, (poly)propylene glycol mono(meth)acrylate, (poly)propylene glycol mono(meth)acrylate; Examples thereof include (poly)tetramethylene glycol mono(meth)acrylates such as (poly)tetramethylene glycol mono(meth)acrylate, (poly)tetramethylene glycol mono(meth)acrylate, and (poly)tetramethylene glycol mono(meth)acrylate. Of these, (poly)ethylene glycol mono(meth)acrylate is preferred.

[0026] Specific examples of the monomer represented by general formula (2) being a (poly)alkylene glycol monoalkyl ether (meth)acrylate include (poly)methylene glycol monomethyl ether (meth)acrylate, (poly)methylene glycol monoethyl ether (meth)acrylate, (poly)methylene glycol monopropyl ether (meth)acrylate, (poly)methylene glycol monobutyl ether (meth)acrylate, and other (poly)methylene glycol monoalkyl ether (meth)acrylates; (poly)ethylene glycol monoalkyl ether (meth)acrylates such as (poly)ethylene glycol monomethyl ether (meth)acrylate, (poly)ethylene glycol monoethyl ether (meth)acrylate, (poly)ethylene glycol monopropyl ether (meth)acrylate, and (poly)ethylene glycol monobutyl ether (meth)acrylate; (poly)propylene glycol monoalkyl ether (meth)acrylates such as (poly)propylene glycol monomethyl ether (meth)acrylate, (poly)propylene glycol monoethyl ether (meth)acrylate, (poly)propylene glycol monopropyl ether (meth)acrylate, and (poly)propylene glycol monobutyl ether (meth)acrylate; Examples thereof include (poly)tetramethylene glycol monoalkyl ether (meth)acrylates such as (poly)tetramethylene glycol monomethyl ether (meth)acrylate, (poly)tetramethylene glycol monoethyl ether (meth)acrylate, (poly)tetramethylene glycol monopropyl ether (meth)acrylate, and (poly)tetramethylene glycol monobutyl ether (meth)acrylate. Of these, (poly)ethylene glycol monoalkyl ether (meth)acrylate is preferred.

[0027] The monomer represented by general formula (1) may be represented by R 2 Similarly, the monomer represented by general formula (2) may be changed to one having an acidic group. 4 may be changed to one having an acidic group.

[0028] The acidic group is a group that can exhibit acidity (Brønsted acidity) in water, and includes not only the acidic group itself, but also its ester group and acid anhydride group. Specific examples of the acidic group include a carboxyl group (-COOH), a sulfo group (-SOH), a phosphono group (-P(=O)(OH)), a phosphinico group (>P(=O)(OH)), a boronic acid group (-B(OH)), a borinic acid group (>BOH), and a silicic acid group (-Si(=O)(OH), -Si(OH)). The acidic group may be an anion in which a proton is dissociated, such as a carboxylato group (-COO-), or may be an acid salt formed with an alkali metal ion such as a sodium ion or a potassium ion.

[0029] The ester group of the acidic group is a carboxylic acid ester (-COOR 5 ), sulfonic acid esters (-SO3R 5 ), phosphate ester (-P(=O)(OR 5 )2), (>P(=O)(OR 5 )), boronic acid ester (-B(OR 5 )2), boric acid ester (>BOR 5 ) etc. The acid anhydride group of the acidic group is a carboxylic acid anhydride (R 5 -CO-O-CO-R 5 ) etc.

[0030] where R 5 is, for example, an alkyl group having 1 to 8 carbon atoms, and in this case, the number of carbon atoms is preferably 1 to 4. 5 is, for example, an alkenyl group having 2 to 8 carbon atoms, and in this case, the number of carbon atoms is preferably 2 to 4. 5 is, for example, an alkynyl group having 2 to 8 carbon atoms, and in this case, the number of carbon atoms is preferably 2 to 4. 5 is, for example, an aryl group having 6 to 10 carbon atoms, and in this case, the number of carbon atoms is preferably 6 to 8.

[0031] Polymerizable monomers with acidic groups act as decomplexing agents, as described below. For example, when an alkylborane-amine complex is mixed with a polymerizable monomer with an acidic group, the monomer decomplexes the alkylborane-amine complex, liberating the alkylborane. Therefore, when an alkylborane-amine complex is used as a polymerization initiator, the polymerization reaction can be initiated by using a polymerizable monomer with an acidic group.

[0032] Specific examples of monomers having an acidic group include (meth)acrylic acid and its anhydride, 1,4-di(meth)acryloxyethylpyromellitic acid, 6-(meth)acryloxyethylnaphthalene-1,2,6-tricarboxylic acid, N-(meth)acryloyl-p-aminobenzoic acid, N-(meth)acryloyl-o-aminobenzoic acid, N-(meth)acryloyl-m-aminobenzoic acid, N-(meth)acryloyl-5-aminosalicylic acid, N-(meth)acryloyl-4-aminosalicylic acid, 4-(meth)acryloxyethyltrimellitic acid and its anhydride, 4-(meth)acryloxybutyltrimellitic acid and its anhydride, 4-(meth)acryloxyhexyltrimellitic acid and its anhydride, 4-(meth)acryloxydecyltrimellitic acid and its anhydride, and 2-(meth)acryloyloxybenzoic acid. Examples of suitable monomers include carboxylic acid or anhydride monomers such as aromatic acid, 3-(meth)acryloyloxybenzoic acid, 4-(meth)acryloyloxybenzoic acid, β-(meth)acryloyloxyethyl hydrogen succinate, β-(meth)acryloyloxyethyl hydrogen maleate, β-(meth)acryloyloxyethyl hydrogen phthalate, 11-(meth)acryloyloxy-1,1-undecanedicarboxylic acid, and p-vinylbenzoic acid; phosphate monomers such as (2-(meth)acryloxyethyl)phosphoric acid, (2-(meth)acryloxyethylphenyl)phosphoric acid, and 10-(meth)acryloxydecylphosphoric acid; and sulfonic acid monomers such as p-styrenesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid. Among these, 4-methacryloxyethyltrimellitic acid and its anhydride are preferred.

[0033] These monomers having an acidic group may be used in combination of two or more kinds. The monomers having an acidic group may also be used as calcium salts.

[0034] Among the above-mentioned exemplified compounds, examples of the monofunctional (meth)acrylate include alkyl (meth)acrylates such as methyl (meth)acrylate and ethyl (meth)acrylate; hydroxyalkyl esters of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate and 1,3-dihydroxypropyl mono(meth)acrylate; Polyethylene glycol mono(meth)acrylates such as triethylene glycol monomethyl ether (meth)acrylate and triethylene glycol mono(meth)acrylate are preferred.

[0035] Specific examples of polyfunctional (meth)acrylates include poly(meth)acrylates of alkane polyols such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hexylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate; Examples of the poly(meth)acrylate include polyoxyalkane polyol poly(meth)acrylates such as colesulfone di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, dibutylene glycol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; aromatic di(meth)acrylates, alicyclic or aromatic epoxy di(meth)acrylates, and polyfunctional (meth)acrylates having a urethane bond in the molecule.

[0036] Moreover, as the polyfunctional (meth)acrylate, a di(meth)acrylate having an ethylene glycol chain in the molecule, such as triethylene glycol di(meth)acrylate or polyethylene glycol di(meth)acrylate, is preferred. Two or more types of (meth)acrylates may be used in combination.

[0037] When styrene is selected as the polymerizable monomer and an organoboron compound is used as the polymerization initiator described below, it is preferable to ensure a long polymerization reaction time (e.g., 72 hours or more) in order to obtain a sufficient polymerization yield. This is because when an organoboron compound is used as the polymerization initiator, it exhibits selectivity for the polymerizable monomer. For example, the e value of styrene monomer does not fall within the range of e values ​​in which the polymerization initiation ability of organoboron compounds is believed to be effectively expressed, and it is thought that the polymerization reaction tends to proceed less easily.

[0038] The e value is an index that is said to represent the degree of resonance stabilization and polarity of a polymerizable monomer. For example, Non-Patent Document 1 [Collection of Polymers, 46, 223-231, 1989 (Polymerization of Vinyl Compounds with Dibutylborinic Acid Ester)] discloses the range of e values ​​(-0.4 to 1.3) of polymerizable monomers that allow organoboron compounds (trialkylborons) to effectively exhibit polymerization initiation ability, and Non-Patent Document 2 [Journal of Computer Chemistry Japan, 23, A9-A14, 2024 (First Calculation of the Qe Value of a Polymer Radical)] discloses the e value (-0.8) of styrene monomer.

[0039] Examples of polymerizable monomers other than (meth)acrylates and styrene include ethylene oxide, maleic anhydride, N-phenylmaleimide, N-cyclohexylmaleimide, and N-vinyl-2-pyrrolidone. These may be used in combination of two or more. They may also be used in combination with either or both of (meth)acrylates and styrene.

[0040] [Polymerization initiator] In this embodiment, an organic boron compound is used as the polymerization initiator. Examples of the organic boron compound include trialkylboron, alkoxyalkylboron, dialkylborane, partially oxidized trialkylboron, and alkylborane-amine complex.

[0041] Specific examples of trialkylborons include trialkylborons having an alkyl group having 2 to 8 carbon atoms, such as triethylboron (TEB), tripropylboron, triisopropylboron, tributylboron (TBB), tri-sec-butylboron, triisobutylboron, tripentylboron, trihexylboron, triheptylboron, trioctylboron, tricyclopentylboron, and tricyclohexylboron. The alkyl group may be a linear alkyl group, a branched alkyl group, or a cycloalkyl group, and the three alkyl groups contained in the trialkylboron may be the same or different.

[0042] Specific examples of alkoxyalkylboron include monoalkoxydialkylboron (alkylborinic acid ester) such as butoxydibutylboron (BDBB), and dialkoxymonoalkylboron (alkylboronic acid ester). The alkyl group of the alkoxyalkylboron and the alkyl portion of the alkoxy group may be the same or different.

[0043] Specific examples of dialkylboranes include dicyclohexylborane and diisoamylborane. The two alkyl groups in a dialkylborane may be the same or different. The two alkyl groups in a dialkylborane may be bonded to form a monocyclic or bicyclic structure. An example of such a compound is 9-borabicyclo[3.3.1]nonane.

[0044] Partially oxidized trialkylboron is a partial oxide of trialkylboron. Partially oxidized tributylboron (TBBO) is preferred. The number of oxygen atoms chemically and structurally contained per molecule of trialkylboron is preferably 0.4 to 1.8, more preferably 0.6 to 1.6, and even more preferably 0.8 to 1.2. That is, when exposing trialkylborane to oxygen gas or air, the amount of oxygen molecules added per 1 mol of trialkylborane is preferably 0.2 to 0.9 mol, more preferably 0.3 to 0.8 mol, and even more preferably 0.4 to 0.6 mol. Tributylboron partial oxide (TBBO) contains butoxydibutylboron (BDBB) as its main component.

[0045] The method for producing the partially oxidized trialkylboron containing the above-mentioned suitable number of oxygen atoms is not particularly limited, and known methods can be used. For example, Patent Document 2 (JP 1974-5143 A) discloses a method for obtaining partially oxidized tributylboron (TBBO) by exposing tributylboron (TBB) to oxygen gas or air. Meanwhile, the above-mentioned Non-Patent Document 1 [Collection of Polymers, 46, 223-231, 1989 (Polymerization of vinyl compounds with dibutylborinic acid ester)] discloses a method for obtaining butoxydibutylboron (BDBB) by reacting tributylboron (TBB) with n-butanol under heating.

[0046] Recently, methods for obtaining butoxydibutylborane (BDBB) with higher purity have been proposed. For example, Non-Patent Document 3 [Journal of Materials Chemistry B, 12, 8911-8918, 2024 (High-purity butoxydibutylborane catalyst enable the low-exothermic polymerization of PMMA bone cement with enhanced biocompatibility and osseointegration)] discloses a method for obtaining BDBB with higher purity by further improving the above-mentioned BDBB production method.

[0047] Specific examples of alkylborane-amine complexes include triethylborane-diaminopropane (TEB-DAP), triethylborane-diethylenetriamine (TEB-DETA), tri-n-butylborane-3-methoxypropylamine (TnBB-MOPA), tri-n-butylborane-diaminopropane (TnBB-DAP), tri-sec-butylborane-diaminopropane (TsBB-DAP), methylaminoethoxydiethylborane (MAEDEB), methylaminoethoxydicyclohexylborane (MAEDCB), and derivatives derived from these. These alkylborane-amine complexes can be used alone or in combination. When using alkylborane-amine complexes, it is preferable to use a decomplexing agent, which is a compound capable of liberating alkylborane from the alkylborane-amine complex, thereby allowing the initiation of polymerization.

[0048] Suitable decomplexing agents include, for example, any acid, the polymerizable monomers having an acidic group described above, or phosphorus oxoacids and their salts among the specific dispersants described below. Suitable acids include Lewis acids (e.g., SnCl4, TiCl4) and Bronsted acids (e.g., carboxylic acids, HCl, H2SO4, phosphonic acid, phosphinic acid, and silicic acid). Suitable carboxylic acids include those represented by general formula (3):

[0049] The above-mentioned suitable acid can be added to the aqueous phase when an oil phase containing a polymerizable monomer and a polymerization initiator is suspended in the aqueous phase to carry out suspension polymerization, and the amount of the acid to be added may be appropriately determined.

[0050] [ka]

[0051] In general formula (3), R 6 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms (preferably an alkyl group having 1 to 4 carbon atoms), an alkenyl group having 2 to 8 carbon atoms (preferably an alkenyl group having 2 to 4 carbon atoms), an alkynyl group having 2 to 8 carbon atoms (preferably an alkynyl group having 2 to 4 carbon atoms), or an aryl group having 6 to 10 carbon atoms (preferably an aryl group having 6 to 8 carbon atoms).

[0052] R 6 The alkyl group, alkenyl group, and alkynyl group in the formula (I) may be linear or branched. R 6 The aliphatic group in may be saturated or unsaturated. R 6 The aryl group in may be unsubstituted or substituted with a substituent such as an alkyl group, an alkoxy group or a halogen atom.

[0053] Examples of the carboxylic acid represented by the general formula (3) include acrylic acid, methacrylic acid, acetic acid, benzoic acid, and p-methoxybenzoic acid.

[0054] Among the organic boron compounds, tributyl boron and partially oxidized tributyl boron are preferred, and partially oxidized tributyl boron is particularly preferred, because these compounds have relatively strong Lewis acidity and exhibit good reactivity with oxygen molecules necessary for functioning as a polymerization initiator. These organic boron compounds can be used alone or in combination of two or more.

[0055] The organoboron compound may be used with the addition of an alcohol. By adding an alcohol to the organoboron compound, the reaction caused by the organoboron compound becomes milder without reducing the polymerization activity, and scorching or ignition when the organoboron compound comes into contact with a material such as paper in the air tends to be suppressed. As will be described later, the alcohol to be added may contain water.

[0056] The alcohol to be added to the organoboron compound preferably has a boiling point at 1 atmospheric pressure of 60°C to 180°C, more preferably 60°C to 120°C. By setting the boiling point of the alcohol to at least the lower limit of the above-mentioned preferred range, it is possible to easily avoid the alcohol added to the polymerization initiator volatilizing and scattering during transportation or storage, which would reduce the ignition suppression effect of the organoboron compound. On the other hand, since the viscosity of alcohol generally tends to increase with its boiling point, by setting the boiling point of the alcohol to at most the upper limit of the above-mentioned preferred range, it is possible to prevent the mixture of the organoboron compound and the alcohol from becoming too viscous, improving the handleability of the polymerization initiator itself, and facilitating mixing of the polymerization initiator and the polymerizable monomer, thereby improving the homogeneity of the resulting mixture of the polymerization initiator and the polymerizable monomer.

[0057] The boiling points of the organic boron compounds tributylboron (TBB) and butoxydibutylboron (BDBB) are suggested in Non-Patent Document 4 [Journal of the American Chemical Society, 83, 3051-3056, 1961 (Air oxidation of trialkylboranes)] and Non-Patent Document 1 [Collection of Polymers, 46, 223-231, 1989 (Polymerization of vinyl compounds with dibutylborinic acid ester)], respectively, and are thought to be 73 to 74°C (2.5 to 3 mmHg) for TBB and 92 to 94°C (8 mmHg) for BDBB.

[0058] Specific examples of alcohols include methanol, ethanol, n-propanol and its isomers, n-butanol and its isomers, n-pentanol and its isomers, n-hexanol and its isomers, and n-heptanol and its isomers. Among these, alcohols having 4 or fewer carbon atoms, i.e., methanol, ethanol, n-propanol and its isomers, and n-butanol and its isomers, are preferred, with ethanol and n-propanol being more preferred. These alcohols can be used alone or in combination.

[0059] The alcohol may contain water. The water content in the alcohol is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of alcohol (pure content excluding water). When the water content is equal to or less than the upper limit of the above-mentioned preferred range, it is easy to avoid the alcohol containing water added to the organoboron compound from volatilizing or scattering during transportation or storage, which would reduce the ignition suppression effect of the organoboron compound. Furthermore, when the organoboron compound is mixed with the alcohol containing water, the formation of liquid-liquid phase separation and / or precipitation of crystalline components can be suppressed, thereby improving the stability of quality.

[0060] The precipitated crystalline components tend to contain a large amount of boric acid compounds derived from organic boron compounds (e.g., boric acid, boric acid esters, boronic acids (alkyldihydroxyboron), and boronic acid esters (alkyldialkoxyboron)).

[0061] When an alcohol is added to an organoboron compound, the organoboron compound to which the alcohol has been added may be heat-treated before use. Heat treatment tends to improve the long-term stability of the quality and performance of the polymerization initiator.

[0062] Among organic boron compounds, trialkylboranes react with alcohols under heating to produce monoalkoxydialkylboranes. For example, the aforementioned Non-Patent Document 1 [Polymers, 46, 223-231, 1989 (Polymerization of vinyl compounds with dibutylborinic acid ester)] and Non-Patent Document 3 [Journal of Materials Chemistry B, 12, 8911-8918, 2024 (High-purity butoxydibutylborane catalyst enable the low-exothermic polymerization of PMMA bone cement with enhanced biocompatibility and osseointegration)] disclose that tributylborane (TBB) reacts with n-butanol under heating to produce butoxydibutylborane (BDBB).

[0063] On the other hand, among organic boron compounds, monoalkoxydialkylborons and dialkoxymonoalkylborons are susceptible to nucleophilic attack on the boron atom by alcohols and water, resulting in exchange reactions. For example, Non-Patent Document 5 [Journal of the Society of Organic Synthetic Chemistry, 56, 45-53, 1998 (New Developments in Arylboron Compounds as Lewis Acid Catalysts)] suggests the instability of dialkoxymonoalkylborons due to exchange reactions caused by alcohols and water.

[0064] In this way, when an alcohol is added to an organoboron compound, a heat treatment is carried out to cause a reaction that may occur due to heating in advance, and further, when a thermally unstable organoboron compound is present, the compound can be transformed or modified in advance to have a thermally stable structure, thereby improving the long-term stability of the quality and performance of the polymerization initiator.

[0065] The heat treatment temperature for the organoboron compound to which an alcohol has been added is desirably 30 to 120°C, preferably 50 to 100°C, and more preferably 60 to 90°C. By keeping the heat treatment temperature at or below the upper limit of the above-mentioned preferred range, evaporation, volatilization, and scattering of the alcohol added to the organoboron compound, and if water is included, the alcohol or water, can be suppressed, and a decrease in the amount of alcohol or water that can react with the organoboron compound can be easily avoided. On the other hand, by keeping the heat treatment temperature at or above the lower limit of the above-mentioned preferred range, reactions that may occur due to heating and / or alteration or modification of the thermally unstable organoboron compound can be promoted.

[0066] The amount of alcohol added (including water when water is included) is preferably 0 to 120 parts by mass, more preferably 5 to 110 parts by mass, and even more preferably 10 to 100 parts by mass, per 100 parts by mass of the organoboron compound. When the amount of alcohol added is at least the lower limit of the above-mentioned preferred range (excluding the case where the lower limit is 0), the effect of suppressing heat generation or ignition is easily exhibited. On the other hand, by ensuring that the amount of alcohol added is equal to or less than the upper limit of the above-mentioned preferred range, the polymerization initiator can fully exhibit its polymerization initiation ability when used.

[0067] The organoboron compound may be used with an aprotic solvent in addition to or instead of alcohol. By adding an aprotic solvent to the organoboron compound, the reaction caused by the organoboron compound becomes more moderate without reducing the polymerization activity, and scorching or ignition tends to be more easily suppressed even when the organoboron compound comes into contact with a member such as paper in air.

[0068] The boiling point of the aprotic solvent added to the organoboron compound at 1 atmosphere is usually preferably 30°C to 150°C, more preferably 50°C to 120°C. Having a boiling point at or above the lower limit of the above preferred range makes it easier to avoid the aprotic solvent added to the polymerization initiator volatilizing and scattering during transportation or storage, which would reduce the ignition suppression effect of the organoboron compound. Meanwhile, since the viscosity of an aprotic solvent generally tends to increase with its boiling point, having a boiling point at or below the upper limit of the above preferred range prevents the mixture of the organoboron compound and the aprotic solvent from becoming too viscous, improving the handleability of the polymerization initiator itself and facilitating the mixing of the polymerization initiator and polymerizable monomer, thereby improving the homogeneity of the resulting mixture of the polymerization initiator and polymerizable monomer.

[0069] The aprotic solvent is preferably a solvent that does not have a group containing active hydrogen, such as a hydroxy group or a mercapto group, that can react with the organoboron compound and that can form a homogeneous solution with the organoboron compound.

[0070] Specific examples of aprotic solvents include hydrocarbons such as n-pentane, n-hexane, cyclohexane, n-heptane, n-octane, benzene, toluene, and xylene; halogenated hydrocarbons such as fluorobenzene, 1,1-dichloroethane, and 1,2-dichloroethane (so-called chlorofluorocarbons); ethers such as diethyl ether, diisopropyl ether, ethylene glycol dimethyl ether, and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, and diethyl ketone; and esters such as methyl acetate, ethyl acetate, and isopropyl acetate. Among these, saturated aliphatic hydrocarbons such as pentane, n-hexane, and heptane, ethers, and esters are preferred, with hexane, diisopropyl ether, and ethyl acetate being more preferred. These aprotic solvents can be used alone or in combination.

[0071] The amount of the aprotic solvent added is preferably 0 to 40 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 10 to 25 parts by mass, relative to 100 parts by mass of the organoboron compound. When the amount of the aprotic solvent added is at least the lower limit of the above-mentioned preferred range (excluding the case where the lower limit is 0), the effect of suppressing heat generation or ignition is easily exhibited. On the other hand, by ensuring that the amount of the aprotic solvent added is equal to or less than the upper limit of the above-mentioned preferred range, the polymerization initiator can fully exhibit its polymerization initiation ability when used.

[0072] When an alcohol and an aprotic solvent are used in combination, the total amount of the alcohol and the aprotic solvent (including water if the alcohol contains water) added is preferably 0 to 150 parts by mass, more preferably 5 to 125 parts by mass, and even more preferably 10 to 100 parts by mass, per 100 parts by mass of the organoboron compound. When the amount of the aprotic solvent added is at least the lower limit of the above-mentioned preferred range (excluding the case where the lower limit is 0), the effect of suppressing heat generation or ignition is easily exhibited. On the other hand, when the total amount of the alcohol and the aprotic solvent added is equal to or less than the upper limit of the above-mentioned preferred range, the polymerization initiator can fully exhibit its polymerization initiation ability when used.

[0073] When either or both of an alcohol and an aprotic solvent are added to an organoboron compound, the alcohol and the aprotic solvent may be used with a reduced amount of dissolved oxygen. By reducing the amount of dissolved oxygen, the amount of oxygen reacting with the organoboron compound can be reduced, thereby preventing a decrease in the polymerization activity of the organoboron compound.

[0074] The method for reducing the amount of dissolved oxygen in the alcohol and aprotic solvent is not particularly limited, and known methods can be used, such as vacuum (reduced pressure) degassing, inert gas bubbling, ultrasonic treatment, and freeze degassing. The methods for reducing the amount of dissolved oxygen may be used alone or in combination of two or more.

[0075] The amount of dissolved oxygen in alcohols and aprotic solvents is desirably 60 mg / L or less, preferably 40 mg / L, and more preferably 20 mg / L, at around room temperature (16 to 30° C.) and under atmospheric pressure of 1 atmosphere. Generally, the lower the polarity of the solvent, the higher the solubility of oxygen. The oxygen solubilities (O2-mol / (O2-mol+solvent-mol)) of major alcohols, aprotic solvents, and water at room temperature (25°C) and an oxygen partial pressure of 1 atmosphere (atm) are calculated in Non-Patent Document 6 [Chemical Reviews, 73, 1-9, 1973 (Thermodynamic Functions of the Solubilities of Gases in Liquids at 25°C)] and Non-Patent Document 7 [Chemical Reviews, 77, 219-262, 1977 (Low-Pressure Solubility of Gases in Liquid Water)], and are as follows (unit: × 10 -4 O2-mol / (O2-mol+solvent-mol)).

[0076] Methanol: 4.147 (Non-Patent Document 6), ethanol: 5.841 (Non-Patent Document 6), n-hexane: 19.3 (Non-Patent Document 6), cyclohexane: 12.48 (Non-Patent Document 6), benzene: 8.165 (Non-Patent Document 6), toluene: 9.09 (Non-Patent Document 6), m-xylene: 11.96 (Non-Patent Document 6), water: 0.2298 (Non-Patent Document 7).

[0077] Using the above literature values, the oxygen solubility (unit: mg / L) at room temperature (approximately 20 to 25°C) and atmospheric pressure of 1 atmosphere (atm) is calculated as follows: Methanol: 69, ethanol: 67, n-hexane: 100, cyclohexane: 78, benzene: 62, toluene: 58, m-xylene: 67, water: 8.6.

[0078] By ensuring that the oxygen solubility of the alcohol and the aprotic solvent at 1 atmospheric pressure (atm) is equal to or less than the upper limit of the above-mentioned preferred range, when either or both of the alcohol and the aprotic solvent are added to the organoboron compound, it is possible to prevent the organoboron compound from being denatured by dissolved oxygen and losing its polymerization activity.

[0079] The amount of the polymerization initiator (net amount excluding both the alcohol and the aprotic solvent when either or both of the alcohol and the aprotic solvent are added) is preferably 0.01 to 36.6 parts by mass, more preferably 0.05 to 18.8 parts by mass, and even more preferably 1.0 to 15.0 parts by mass, per 100 parts by mass of the polymerizable monomer. When the amount of the polymerization initiator is equal to or greater than the lower limit of the above-mentioned preferred range, the polymerization proceeds easily, whereas when the amount is equal to or less than the upper limit of the above-mentioned preferred range, polymer particles having a high molecular weight are easily obtained.

[0080] [Dispersant] In this embodiment, one or more dispersants (specific dispersants) selected from the group consisting of phosphorus oxoacids and their salts (phosphoric acid and / or phosphates, phosphorous acid and / or phosphites, hypophosphorous acid and / or hypophosphites), alkaline (earth) metal iodides, alkaline (earth) metal fluorides, and quaternary ammonium salts are added to the aqueous phase. In addition to the specific dispersant, a polymer dispersant such as polyethylene glycol (PEG) or polyvinyl alcohol (PVA) may be used in combination.

[0081] Phosphoric acid and phosphates include, for example, phosphoric acid (H3PO4), strong phosphoric acid (H (n+2) P n O (3n+1) (n≧2)), sodium dihydrogen phosphate (NaH2PO4), disodium hydrogen phosphate (Na2HPO4), trisodium phosphate (Na3PO4·12H2O), sodium pyrophosphate (Na4P2O4), sodium tripolyphosphate (Na5P3O 10), sodium acid pyrophosphate (Na2H2P2O7), sodium tetrapolyphosphate (Na6P4O 13 ), sodium pentapolyphosphate (Na7P5O 16 ), sodium metaphosphate (Na n H2P n O 3n+1 ), Ultraporin (Na n H m (PO3) (n+m) (n, m≧1)) and other sodium phosphate salts; Calcium phosphate salts such as monocalcium phosphate (Ca(H2PO4)2·0~1H2O), calcium hydrogen phosphate (CaHPO4·0~2H2O), tricalcium phosphate (3Ca3(PO4)2·Ca(OH)2), calcium dihydrogen pyrophosphate (CaH2P2O7), calcium pyrophosphate (Ca2P2O7), tricalcium phosphate (Ca3(PO4)2), octacalcium phosphate (Ca8H2(PO4)6·5H2O), α-TCP (monoclinic tricalcium phosphate), α'-TCP (hexagonal tricalcium phosphate), β-TCP (low-temperature polymorph tricalcium phosphate), hydroxyapatite (HAP, 3Ca3(PO4)2·Ca(OH)2), tetracalcium phosphate (TTCP, Ca4(PO4)2O), and amorphous calcium phosphate (ACP, Ca3(PO4)2·nH2O); aluminum phosphate salts such as monoaluminum phosphate (Al(H2PO4)3), dialuminum phosphate (Al2(HPO4)3), trialuminum phosphate (AlPO4), and aluminum metaphosphate (Al(PO3)3); ammonium phosphate salts such as monoammonium phosphate (NH4H2PO4) and diammonium phosphate ((NH4)2HPO4); Monopotassium phosphate (KH2PO4), dipotassium phosphate (K2HPO4), tripotassium phosphate (K3PO4 0~3H2O), potassium pyrophosphate (K4P2O7), potassium tripolyphosphate (K5P3O 10 ), potassium metaphosphate ((KPO3) n (n≒10,000)) and other potassium phosphate salts; magnesium phosphate salts such as monobasic magnesium phosphate (Mg(H2PO4)2·4H2O), dibasic magnesium phosphate (MgHPO4·3H2O), tribasic magnesium phosphate (Mg3(PO4)2·8H2O), magnesium pyrophosphate (Mg2P2O7), and magnesium metaphosphate (Mg(PO3)2); Examples include iron phosphates such as ferric pyrophosphate (Fe4(P2O7)3).

[0082] Examples of phosphorous acid and phosphites include phosphorous acid (H3PO3) and disodium phosphite (Na2HPO3·0-5H2O). Examples of hypophosphorous acid and hypophosphites include hypophosphorous acid (H3PO2) and disodium hypophosphite (Na2HPO2·0-5H2O).

[0083] Examples of alkali metals that constitute alkali metal iodides and alkali metal fluorides include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Examples of alkaline earth metals that constitute alkaline earth metal iodides and alkaline earth metal fluorides include magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0084] Examples of quaternary ammonium salts include ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, tetra-n-hexylammonium hydroxide, choline, hexadecyltrimethylammonium hydroxide, N,N,N-tris(polyoxyethylene)-N-methylammonium hydroxide, phenyltrimethylammonium hydroxide (PTAH), 3-(trifluoromethyl)phenyltrimethylammonium hydroxide, benzyltrimethylammonium hydroxide, and N,N,N-trimethyl-1-adamantylammonium hydroxide, as well as aqueous solutions, methanol solutions, and tetrahydrofuran (THF) solutions thereof; Ammonium fluorides such as tetra-n-butylammonium fluoride hydrate, as well as their aqueous, methanolic and tetrahydrofuran (THF) solutions; Tetramethylammonium chloride, triethylmethylammonium chloride, tetraethylammonium chloride, choline chloride, chlorocholine chloride, bis(2-hydroxyethyl)-dimethylammonium chloride, (2-methoxyethoxymethyl)triethylammonium chloride, tritria-n-propylammonium chloride, tetra-n-butylammonium chloride, trimethyl[3-(trimethoxysilyl)-propyl]ammonium chloride, trimethyl[3-(triethoxysilyl)-propyl]ammonium chloride, tetra-n-pentylammonium chloride, tetrabutylmethylammonium chloride, methyltri-n-octylammonium chloride, n-octyltrimethylammonium chloride, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, trimethyltetradecylammonium chloride, hexadecyltrimethylammonium chloride, trimethylstearylammonium chloride, diallyldimethylammonium chloride, didodecyldimethylammonium chloride Phosphocholine chloride, methacholine chloride, β-metahcholine chloride, (3-chloro-2-hydroxypropyl)trimethylammonium chloride, carbachol, lauroylcholine chloride, hexamethonium chloride hydrate, phosphocholine chloride sodium hydrate, phosphocholine chloride calcium hydrate, (3-acrylamidopropyl)trimethylammonium chloride, methacroylcholine chloride, succinylcholine chloride hydrate, bethanechol chloride, trimethylphenylammonium chloride, benzyltrimethylammonium chloride ethylammonium chloride, benzyltriethylammonium chloride, benzyltri-n-butylammonium chloride, benzyldodecyldimethylammonium chloride, benzalkonium chloride, tetradecyldimethylammonium chloride, benzylcetyldimethylammonium chloride, benzyldimethylstearylammonium chloride, benzoylcholine chloride, benzyldimethylphenylammonium chloride, benzethonium chloride, N-(2-acryloyloxyethyl)-N-benzyl-N,Ammonium chlorides such as N-dimethylammonium chloride, glycidyltrimethylammonium chloride, N-benzylcinchonidinium chloride (BCDC), 1-butyl-1-methylpyrrolidinium chloride, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM), cetylpyridinium chloride, and their aqueous, methanol, and tetrahydrofuran (THF) solutions; Acetylcholine bromide, tetramethylammonium bromide, tetraethylammonium bromide, choline bromide, tetra-n-propylammonium bromide, tetra-n-butylammonium bromide, tetra-n-pentylammonium bromide, tetra-n-hexylammonium bromide, tetra-n-heptylammonium bromide, tetra-n-octylammonium bromide, tetra(decyl)ammonium bromide, trimethylpropylammonium bromide, bromocholine bromide, (3-bromopropyl)trimethylammonium bromide n-Butyltrimethylammonium bromide, n-Hexyltrimethylammonium bromide, n-Octylammonium bromide, Trimethylnonylammonium bromide, Decyltrimethylammonium bromide, Dodecyltrimethylammonium bromide, Lauryltrimethylammonium bromide, Tetradecylammonium bromide, Hexadecyltrimethylammonium bromide, Heptadecyltrimethylammonium bromide, Trimethylstearylammonium bromide, Hexyldimethyloctylammonium bromide, Dimethylammonium bromide Methyldioctylammonium bromide, didecyldimethylammonium bromide, dilauryldimethylammonium bromide, dimethyldimyristylammonium bromide, ethylhexadecyldimethylammonium bromide, dimethyldipalmitylammonium bromide, dimethyldioctadecylammonium bromide, trimethylvinylammonium bromide, hexamethonium bromide, decanonium bromide, methacholine bromide, trimethylphenylammonium bromide, benzyltrimethylammonium bromide, benzyltriethylammonium bromide ammonium bromide, benzyltri-n-butylammonium bromide, benzyldodecyldimethylammonium bromide, benzoylcholine bromide, 1-methyl-1-propylpyrrolidinium bromide, 1-butyl-1-methylpyrrolidinium bromide, 3-(trifluoromethyl)phenyltrimethylammonium bromide, neostigmine bromide, valethamate bromide, methylnaltrexone bromide, buscopan, N-methylhomatropinium bromide, scopolamine methyl bromide, tiotropium bromide hydrate, 1,1'-(decane-1,Ammonium bromides such as (10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2.]octane]dibromide, glycopyrrolate, (11bS)-2,6-bis[bis[3,5-bis(trifluoromethyl)phenyl]hydroxymethyl]-3,5-dihydrospiro[4H-dinaphtho[2,1-c:1',2'-e]azepine-4,4'-morpholinium]bromide, and 4-ethyl-4-methylmorpholinium bromide, as well as their aqueous, methanol, and tetrahydrofuran (THF) solutions; Choline iodide, acetylcholine iodide, butyrylcholine iodide, butyrylthiocholine iodide, tetramethylammonium iodide, ethyltrimethylammonium iodide, tetraethylammonium iodide, triethylcholine iodide, tetra-n-propylammonium iodide, tetra-n-butylammonium iodide, tetra-n-pentylammonium iodide, tetra-n-hexylammonium iodide, tetra-n-heptylammonium iodide, tetra-n-octylammonium iodide, ethyltri-n-propylammonium iodide, tri-n-butylmethylammonium iodide, dimethyldioctylammonium iodide Examples of ammonium iodides include tadecylammonium iodide, β-methylcholine iodide, decamethonium iodide, trimethylphenylammonium iodide, triethylphenylammonium iodide, benzyltriethylammonium iodide, benzoylcholine iodide, benzoylthiocholine iodide, 3-(trifluoromethyl)phenyltrimethylammonium iodide, trimethyl[2-[(trimethylsilyl)methyl]benzyl]ammonium iodide, isopropamide iodide, and 5-azoniaspiro[4.4]nonane iodide, as well as aqueous, methanol, and tetrahydrofuran (THF) solutions thereof.

[0085] Among the specific dispersants, phosphates, alkali metal iodides, alkali metal fluorides, and tetra-n-butylammonium salts are preferred because they have high affinity with the boron atoms contained in the polymerization initiator, and therefore can effectively and efficiently transfer the polymerization initiator from the oil phase to the aqueous phase, thereby substantially reducing the amount of polymerization initiator in the oil phase during suspension polymerization. The specific dispersants may be used alone or in combination of two or more.

[0086] When a polymeric dispersant is not used, the amount of the specific dispersant is preferably 0.01 to 35.5 parts by mass, more preferably 0.05 to 20.6 parts by mass, and even more preferably 0.1 to 15.0 parts by mass, per 100 parts by mass of polymerizable monomer. When the amount of the specific dispersant is equal to or greater than the lower limit of the above-mentioned preferred range, migration of the polymerization initiator from the surface of the droplets (oil phase) formed by the mixture of polymerizable monomer and polymerization initiator to the aqueous phase during the suspension polymerization reaction proceeds effectively and efficiently. Additionally, aggregation (adhesion) between droplets (oil phase) is suppressed, allowing for efficient production of spherical polymer particles. When the amount is equal to or less than the upper limit, the amount of specific dispersant adhering to the particle surface after removal of the polymer particles from the polymerization system can be reduced, making the washing process of the polymer particles easier and simpler.

[0087] Dispersants that can be used in combination with the specific dispersant include polymeric dispersants, such as polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyoxyethylene alkyl ether, polyalkylene polyamine, polyacrylamide, polyoxypropylene-polyoxyethylene block copolymer, and polymer starch; Cationic (cationic) polymeric dispersants such as polyethyleneimine (PEI), aminoalkyl (meth)acrylate copolymers, polyvinylimidazole (PVI), and satokinesan; Examples include anionic polymer dispersants such as styrene-maleic anhydride copolymer, naphthalene sulfonate formalin condensate, polyacrylate, carboxymethyl cellulose (CMC), polystyrene sulfonate, acrylamide-acrylic acid copolymer, and sodium alginate.

[0088] When a polymeric dispersant is used in combination, the amount of the specific dispersant is preferably 0.01 to 15.2 parts by mass, more preferably 0.05 to 10.6 parts by mass, and even more preferably 0.1 to 6.5 parts by mass, per 100 parts by mass of the polymerizable monomer. When the amount of the specific dispersant is equal to or greater than the lower limit of the above-mentioned preferred range, aggregation (adhesion) of droplets (oil phase) formed by the polymerizable monomer during the suspension polymerization reaction can be suppressed, thereby efficiently obtaining spherical polymer particles. When the amount is equal to or less than the upper limit, the amount of the specific dispersant, polymeric dispersant, etc. adhering to the particle surface after the polymer particles are removed from the polymerization system can be reduced, making the washing process of the polymer particles easier and simpler.

[0089] When a polymeric dispersant is used, the amount of polymeric dispersant is preferably 0.01 to 35.5 parts by mass, more preferably 0.05 to 20.6 parts by mass, and even more preferably 0.1 to 15.0 parts by mass, per 100 parts by mass of polymerizable monomer. When the amount of polymeric dispersant is equal to or greater than the lower limit of the above-mentioned preferred range, aggregation (adhesion) of droplets (oil phase) formed by the polymerizable monomer during the suspension polymerization reaction can be suppressed, thereby efficiently obtaining spherical polymer particles. When the amount is equal to or less than the upper limit, the amount of polymeric dispersant adhering to the particle surface after removal of the polymer particles from the polymerization system can be reduced, making the washing process of the polymer particles easier and simpler.

[0090] [Polymerization conditions] The polymerization method in this embodiment is suspension polymerization. To suspend the oil phase containing the polymerizable monomer and the polymerization initiator in the aqueous phase, it is preferable to drop the oil phase into the aqueous phase while stirring the aqueous phase. After sufficient suspension, the reaction is carried out by maintaining a predetermined reaction temperature for a predetermined time.

[0091] The reaction temperature is preferably 20 to 100°C, more preferably 40 to 90°C, and even more preferably 50 to 70°C. The reaction time varies depending on the reaction temperature, but is preferably 2 to 168 hours, more preferably 3 to 24 hours, and even more preferably 3 to 16 hours.

[0092] <Mechanism of action> [Molecular weight] When polymerizing a polymerizable monomer using an organoboron compound as a polymerization initiator, the polymerization mechanism is radical polymerization. In radical polymerization, the polymerization initiator generates an active radical, which reacts with the polymerizable monomer to generate a growing radical (initiation reaction), and this growing radical then adds to another polymerizable monomer in a chain reaction (propagation reaction), resulting in a polymer.

[0093] On the other hand, a reaction in which growing radicals lose their polymerization activity due to recombination or disproportionation between them is called a "termination reaction," and a reaction in which a growing radical reacts with other chemical species in the polymerization system and moves or restarts is called a "chain transfer reaction." These termination and chain transfer reactions hinder the improvement of the degree of polymerization of the polymer.

[0094] Since the amount (concentration) of radicals does not change during the stage where propagation reactions are dominant, it is thought that the rate of radical generation originating from the polymerization initiator and the rate of radical disappearance due to termination reactions are equal. Therefore, if termination reactions do not occur, as long as polymerizable monomers are present in the polymerization system, the degree of polymerization will increase and the molecular weight of the polymer will also increase. In other words, if only the termination reactions can be suppressed, the molecular weight of the resulting polymer can be increased.

[0095] The termination reaction is a diffusion-controlled reaction. This is because the viscosity of the polymerization system increases as the polymerization reaction progresses, and the diffusion rate of the growing radicals in the polymerization system decreases, suppressing the termination reaction due to recombination or disproportionation of the growing radicals. For example, this is described in Non-Patent Document 8 [Network Polymer, 30, 234-249, 2009 (Radical Polymerization)].

[0096] Generally, in bulk polymerization, in which only polymerizable monomers are radically polymerized without using a solvent, the increase in viscosity of the polymerization system that occurs during the polymerization process suppresses termination reactions, resulting in a cycle of "progression of polymerization → increase in viscosity → suppression of termination reactions → further progression of polymerization," ultimately resulting in an explosive increase in polymerization yield. This phenomenon has been known for a long time and is called the cage effect (Trommsdorff-Norrish effect, gel effect, or cage effect).

[0097] This cage effect is further enhanced by adding particles that are partially soluble in the polymerizable monomer, such as polymer particles with a molecular structure similar to that of the polymerizable monomer. Hard tissue repair compositions (including orthopedic bone cements) that utilize this property are disclosed, for example, in Patent Document 3 (WO2019-181477).

[0098] As described above, the termination reaction is a diffusion-controlled reaction. Therefore, it is generally considered that the termination reaction can be suppressed and the molecular weight of the produced polymer can be improved by reducing the amount (concentration) of radicals in the polymerization system and / or setting the polymerization temperature low. Therefore, in general, the smaller the amount of polymerization initiator used, the easier it is to obtain a polymer with a higher molecular weight. However, if the amount of polymerization initiator used is too small, it becomes difficult to initiate the polymerization reaction, so there is a limit to how much the amount of polymerization initiator can be reduced.

[0099] According to this embodiment, polymer particles having a large molecular weight can be easily obtained while using a polymerization initiator in an amount (concentration) that can sufficiently initiate the polymerization reaction. This is thought to be due to the following three factors.

[0100] (First factor) During suspension polymerization, a specific dispersant and, if necessary, a polymeric dispersant are used, so that the droplets (oil phase) formed by the mixture of polymerizable monomer and polymerization initiator are maintained in a good suspension state, with the droplets being finely dispersed and spherical. As a result, the interface between the oil phase and the aqueous phase increases, making it easier for the polymerization initiator present in the oil phase to migrate to the aqueous phase in an appropriate amount, and the amount (concentration) of the polymerization initiator in the oil phase decreases.

[0101] (Second factor) It is presumed that this is because the specific dispersant used during suspension polymerization has a high affinity with the boron atoms contained in the polymerization initiator, effectively and efficiently transferring the polymerization initiator from the oil phase to the aqueous phase and substantially reducing the amount (concentration) of the polymerization initiator in the oil phase. According to frontier orbital theory, the boron atom contained in the polymerization initiator has an empty p orbital, making it Lewis acidic, and therefore it is thought to exhibit high affinity with specific dispersants that exhibit Lewis basicity.

[0102] For example, among the specific dispersants, anion species (negative ion species) such as phosphate ions, phosphite ions, hypophosphite ions, iodide ions, and fluoride ions derived from phosphoric acid and phosphate salts, phosphorous acid and phosphites, hypophosphorous acid and hypophosphites, alkali metal iodides, and alkali metal fluorides are thought to easily act directly on the vacant p orbital on the boron atom and exhibit high affinity.

[0103] Furthermore, cationic species (cationic species) such as alkali metal ions derived from alkali metal iodides, alkali metal fluorides, and quaternary ammonium salts, and ammonium ions, are thought to exhibit high affinity with polymerization initiators containing boron atoms by coordinating with water or oxygen (dissolved oxygen in water or oxygen atoms possessed by organoboron-based polymerization initiators) present in the polymerization system and / or by undergoing complex formation. In this way, it is presumed that the specific dispersant has a high affinity for the boron atoms contained in the polymerization initiator, and therefore effectively and efficiently transfers the polymerization initiator in the oil phase to the aqueous phase.

[0104] When an alkali metal chloride or an alkali metal bromide is used instead of the specific dispersant, it is difficult to obtain polymer particles with a large molecular weight. This is thought to be because, as will be explained below, chloride ions or bromide ions have poor affinity with polymerization initiators containing boron atoms. According to the HSAB (hard and soft acids and bases) principle, acids and bases can be classified as hard or soft based on a scale (index) that represents the affinity of the acid or base with its pair. Hard acids and bases generally have a small central atom, high electronegativity (the relative strength with which an atom attracts electrons), and a high charge density. Soft acids and bases have the opposite properties.

[0105] Hard acids have a high positive charge density, so they have a high affinity with hard bases, which have a high negative charge density, due to electrostatic interactions.On the other hand, soft acids and soft bases have a high affinity due to frontier orbital interactions, because the difference in energy levels between their LUMO (Lowest Unoccupied Molecular Orbital) and HOMO (Highest Occupied Molecular Orbital) is small. The classification of acids and bases based on this HSAB (hard and soft acids and bases) principle is described, for example, in Non-Patent Document 9 [Colorants, 70, 526-537, 1997 (Adhesion and Acids and Bases)].

[0106] In contrast, a base with an intermediate hardness / softness index has a low affinity with an acid, regardless of the hardness / softness index of the acid. Therefore, chloride ions or bromide ions derived from alkali metal chlorides or alkali metal bromides, which are generally classified as medium to slightly hard bases, are also thought to have poor affinity with polymerization initiators containing boron atoms. For this reason, it is presumed that chloride ions or bromide ions cannot effectively transfer the polymerization initiator in the oil phase to the aqueous phase, and as a result, the resulting polymer particles do not achieve a high molecular weight.

[0107] (Third factor) In the case of organic peroxides and the like, which are commonly used as polymerization initiators in suspension polymerization reactions, the polymerization temperature must be set relatively high (generally about 70°C or higher) to improve reactivity. However, in this embodiment, an organic boron-based polymerization initiator is used as the polymerization initiator, so the polymerization reaction proceeds even at a relatively low temperature. This is thought to enable the molecular weight of the resulting polymer to be improved.

[0108] [Glass transition temperature Tg] According to this embodiment, the glass transition temperature Tg of the obtained polymer particles is likely to be high, that is, the heat resistance is likely to be improved. The reason for this is presumably due to the increase in the molecular weight of the polymer particles, particularly the number average molecular weight (Mn). The glass transition temperature (Tg) of the polymer particles is thought to improve depending on the decrease in the amount (free volume) of the polymer terminals that accompanies the increase in the number average molecular weight (Mn). Therefore, the polymer particles obtained in this embodiment, which have a relatively large number average molecular weight (Mn), have a high glass transition temperature (Tg).

[0109] The improvement in the glass transition temperature Tg associated with an increase in the number-average molecular weight (Mn) of polymer particles is suggested in Non-Patent Document 10 [Journal of Applied Physics, 21, 581-591, 1950 (Second-Order Transition Temperatures and Related Properties of Polystyrene. I. Influence of Molecular Weight)].

[0110] [Water absorption rate, oil absorption rate, G IC value] According to this embodiment, the water absorption rate and oil absorption rate of the molded article obtained from the polymer particles, as well as the surface dissipation energy limit value (GIC This is thought to be due to the following two factors.

[0111] (First factor) In this embodiment, an organic boron-based polymerization initiator is used as the polymerization initiator, and therefore the resulting polymer particles are thought to contain boric acid-based compounds derived from the polymerization initiator (e.g., boric acid, boric acid esters, boronic acids (alkyldihydroxyboron), and boronic acid esters (alkyldialkoxyboron)). The boric acid compound or the like contained in the obtained polymer particles in a suitable amount is G IC It is presumed that it acts as a functional agent that is effective in improving values, etc.

[0112] (Second factor) In this embodiment, since an organic boron-based polymerization initiator is used as the polymerization initiator, it is considered that boron atoms are incorporated into the main chain of the resulting polymer. When boron atoms are incorporated into the polymer main chain, it is expected that the chemical properties and three-dimensional structure of the resulting polymer particles and / or their molded bodies will be different from those of the original polymer (a polymer obtained using an organic peroxide or the like that is commonly used as a polymerization initiator). This difference will affect the water absorption rate, oil absorption rate, and G IC It is estimated that this has contributed to the improvement of values.

[0113] The possibility of incorporating boron atoms into the polymer main chain is suggested in Non-Patent Document 11 [Reports of Institute of Biomaterials and Bioengineering, 37, 4-15, 2003 (study on MMA resins in dentistry using tributylborane as a polymerization initiator)].

[0114] <Polymer particles> [Boron element content] The polymer particles according to one embodiment of the present invention have an elemental boron content of 0.01 to 0.30 mass%, preferably 0.01 to 0.30 mass%, more preferably 0.025 to 0.30 mass%, and even more preferably 0.05 to 0.25 mass%, based on the total mass of the polymer particles.

[0115] When the content of boron element is equal to or greater than the above lower limit, it becomes possible to shorten the time required for the suspension polymerization reaction and / or set the set temperature relatively low, thereby facilitating the production of polymer particles (suspension polymerization).When the content of boron element is equal to or less than the above upper limit, it becomes possible to obtain polymer particles with a high molecular weight.

[0116] Polymer particles having a boron content of 0.25% by mass or less can be suitably produced by the method for producing polymer particles of this embodiment, which is believed to be because, as described above, the method for producing polymer particles of this embodiment reduces the amount (concentration) of the polymerization initiator in the oil phase and allows the set temperature to be set low. The content of boron element is a value determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0117] [Units that make up polymer particles] The polymer particles of this embodiment are preferably polymer particles having units derived from one or more polymerizable monomers selected from the group consisting of (meth)acrylates and styrenes. Specific examples and preferred examples of (meth)acrylates are the same as those explained in the method for producing polymer particles of this embodiment.

[0118] The proportion of units derived from one or more polymerizable monomers selected from the group consisting of (meth)acrylate and styrene in all units constituting the polymer particles of this embodiment is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and particularly preferably 100 mass%.

[0119] [Molecular weight and glass transition temperature] When the polymer particles are polymer particles mainly composed of units derived from methyl methacrylate (preferably polymer particles consisting of units derived from methyl methacrylate), the weight average molecular weight (Mw) is preferably 250,000 or more, more preferably 250,000 to 2,000,000, and even more preferably 300,000 to 1,700,000. The glass transition temperature is preferably 84°C or more, more preferably 84 to 130°C, and even more preferably 85 to 110°C.

[0120] When the polymer particles are polymer particles mainly composed of units derived from methyl acrylate (preferably polymer particles consisting of units derived from methyl acrylate), the weight average molecular weight (Mw) is preferably 1,200,000 or more, more preferably 1,200,000 to 2,000,000, and even more preferably 1,500,000 to 1,950,000. The glass transition temperature is preferably 5.0°C or more, more preferably 5.0 to 10°C, and even more preferably 5.0 to 7.5°C.

[0121] When the polymer particles are polymer particles mainly composed of units derived from butyl acrylate (preferably polymer particles consisting of units derived from butyl acrylate), the weight average molecular weight (Mw) is preferably 140,000 or more, more preferably 140,000 to 1,000,000, and even more preferably 300,000 to 950,000.The glass transition temperature is preferably 2.5°C or more, more preferably 2.5 to 10°C, and even more preferably 2.5 to 7.0°C.

[0122] When the polymer particles are polymer particles mainly composed of units derived from methyl (meth)acrylate and styrene (preferably polymer particles composed of units derived from methyl methacrylate and styrene), the weight average molecular weight (Mw) is preferably 300,000 or more, more preferably 300,000 to 1,500,000, and even more preferably 300,000 to 1,000,000. The glass transition temperature is preferably 50°C or more, more preferably 50 to 130°C, and even more preferably 50 to 110°C.

[0123] When the polymer particles are polymer particles mainly composed of units derived from styrene (preferably polymer particles consisting of units derived from styrene), the weight average molecular weight (Mw) is preferably 150,000 or more, more preferably 150,000 to 1,000,000, and even more preferably 150,000 to 700,000. The glass transition temperature is preferably 59°C or more, more preferably 60 to 130°C, and even more preferably 70 to 110°C.

[0124] When the polymer particles have a molecular weight equal to or greater than the lower limit of the above-mentioned preferred range, it becomes easier to obtain a molded article having improved durability properties such as toughness, heat resistance, oil resistance, and water resistance.

[0125] The polymer particles preferably have a polydispersity (Mw / Mn) calculated by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn) of 2.0 to 10.0, more preferably 2.0 to 9.0, and even more preferably 2.5 to 8.5. When the polydispersity (Mw / Mn) is within the above-mentioned preferred range, it is possible to impart molding processability, such as the ability to mold the polymer particles at a relatively low temperature, and excellent mechanical strength to a molded article obtained from the polymer particles.

[0126] The weight average molecular weight (Mw), number average molecular weight (Mn) and polydispersity (Mw / Mn) of the polymer particles are values ​​determined by gel permeation chromatography (GPC) in terms of standard polystyrene. The glass transition temperature (Tg) of the polymer particles is the "midpoint glass transition temperature: Tmg" among the glass transition temperatures specified in JIS K 7121-1987 "Method for measuring transition temperatures of plastics." The specific measurement method will be described in detail in the examples.

[0127] [Volume average particle size (D50)] The volume average particle size D50 of the polymer particles is preferably from 5 to 300 μm, more preferably from 15 to 200 μm, and even more preferably from 20 to 150 μm. When the volume average particle diameter D50 of the polymer particles is at least the lower limit of the above-mentioned preferred range, the step of removing the polymer particles from the polymerization system by filtration or the like and / or the step of washing the polymer particles can be carried out more easily and simply. Furthermore, the mechanical strength and rigidity of the polymer particles themselves tend to be high. When the volume average particle diameter D50 is at most the upper limit, the surface area per volume (specific surface area) of the polymer particles is large, and when the polymer particles are to be given additional properties and / or modified, the chemical reactions, adsorption, and other reactions can be carried out more quickly and easily. The volume average particle size D50 of the polymer particles is a value measured by a laser diffraction / scattering method.

[0128] <Molded body> A method for producing a molded article according to one aspect of the present invention is a method for molding polymer particles obtained by the method for producing a polymer according to the present aspect. The method for forming the polymer particles is not particularly limited, and known molding methods can be used, such as injection molding, compression molding, blow molding, extrusion molding, rotational molding, casting, solvent casting, and 3D printing using fused deposition modeling (FDM).

[0129] Examples of the shapes of the molded bodies include, in addition to general-purpose shapes such as flat plates, sheets, and films, three-dimensional shapes such as cell culture vessels (materials) such as petri dishes, flasks, multi-plates, and cell culture scaffolds; artificial joints such as acetabular cups, artificial femoral heads, and stems; interbody fusion devices (materials) such as intervertebral cages, spinal cages, and vertebral stents; bone spacers such as cervical spacers, lumbar spacers, spinous process spacers, vertebral arch spacers, and iliac spacers; internal fixation devices (materials) used to fix fractures (including osteotomy) such as pituitary plates, epiphyseal plates, tibial plates, femoral plates, pedicle screws, and intramedullary nails; artificial organ materials such as artificial esophagus, artificial valves, artificial blood vessels, cochlear implants, and intraocular lenses; and biological implant materials such as artificial bones, artificial teeth / dentures, dental composite resins, denture bases, and implant scaffolds. The molded article obtained by the manufacturing method of this embodiment tends to have excellent durability properties such as toughness, heat resistance, oil resistance, and water resistance.

[0130] The polymer particles or molded articles may be sterilized as needed. For the sterilization, an appropriate sterilization method selected from known methods for medical materials, such as autoclave (high-pressure steam) sterilization, dry heat sterilization, radiation (gamma rays, electron beams, X-rays) sterilization, gas-phase sterilization with EO (ethylene oxide) gas or hydrogen peroxide gas, and supercritical carbon dioxide treatment, can be used. Among these, radiation sterilization or gas-phase sterilization with EO (ethylene oxide) gas is preferred from the viewpoint of suppressing changes in the quality and performance of the polymer particles or molded articles, and gas-phase sterilization with EO (ethylene oxide) gas is particularly preferred from the viewpoint of suppressing a decrease in molecular weight.

[0131] The significant decrease in the weight-average molecular weight (Mw) and polydispersity (Mw / Mn) of polymethyl methacrylate (PMMA) due to radiation sterilization is described, for example, in Patent Document 4 (JP 2003-12816 A) and Non-Patent Document 12 [Journal of the Mechanical Behavior of Biomedical Materials, 3, 94-101, 2010 (Dependence of in vitro fatigue properties of PMMA bone cement on the polydispersity index of its powder)]. Patent Document 4 also discloses that a good correlation is observed between the radiation dose and the reciprocal of the weight-average molecular weight (Mw) of polymethyl methacrylate (PMMA) after radiation exposure.

[0132] (Sterilization or Aseptic Standards) The sterilization conditions may be set so as to satisfy the standards for the sterility required in the environment in which the polymer particles or molded articles for treatment are used in Japan and other countries. As for the sterility, the polymer particles or molded articles sterilized by the above sterilization method have a sterility assurance level (SAL) of 10 or more. -6 It is preferable to adopt a state in which a minimum of 1 part per million (1 part per million) is achieved. It is also preferable to adopt the same standard as above for aseptic packaging of polymer particles or molded articles.

[0133] When the polymer particles or molded articles are sterilized and aseptically packaged in a packaging material or the like, examples of the packaging material include sealable resin containers (blisters, pouches, bags) that have gas barrier properties and can prevent moisture absorption by the polymer particles or molded articles, as well as ampoules and vials. Other examples include resin nonwoven fabrics and sterilized paper for gas-phase sterilization using ethylene oxide (EO) gas, hydrogen peroxide gas, or the like. [Example]

[0134] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples.

[0135] <Methods for measuring and evaluating polymer particles> The physical properties of the polymer particles in each example were measured and evaluated by the following methods.

[0136] [Molecular weight] The weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity (Mw / Mn) were measured by gel permeation chromatography (GPC) in terms of standard polystyrene. Specifically, the polymer particles obtained in each example were dissolved in reagent-grade tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the solution was filtered through a hydrophobic 0.45 μm polytetrafluoroethylene filter.

[0137] The filtered solution was used as the measurement sample, and the weight-average molecular weight (Mw) of the polymer was measured in terms of standard polystyrene using a high-performance liquid chromatograph (Shimadzu Corporation, LC-10AD), two serially connected separation columns (Agilent Technologies, PLgel (10 μm) MIXED-B, 7.5 × 300 mm), and a detector (Shodex, RI-101). The eluent was tetrahydrofuran for high-performance liquid chromatograph (with stabilizer) (Fujifilm Wako Pure Chemical Industries, Ltd.).

[0138] The flow rate of the eluent was 1.0 mL / min, the amount of the measurement sample injected was 100 μL, and the temperature of the separation column was 40°C. In addition, polystyrene from Agilent Technologies (10 types with Mp (peak top molecular weight) of 580, 2880, 10330, 29460, 75050, 128700, 316500, 739500, 2328000, and 6570000) was used to create calibration curves for Mw and Mn.

[0139] [Boron element content] The boron element content (B content) of the polymer particles was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). Specifically, approximately 50 mg of polymer particles from each example was weighed and subjected to wet decomposition using a microwave decomposition method using nitric acid (manufactured by Kanto Chemical Co., Ltd.). The solution was then adjusted to 50 mL with pure water to serve as the test solution, which was then quantified using a measuring device 720-ES (manufactured by Agilent Technologies). The standard reagent for the calibration curve was B1000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., for ICP analysis), the internal standard element was Y (yttrium), and the RF output was 1.3 kW.

[0140] [Glass transition temperature] First, in each example, polymer particles obtained by drying at 70°C for 12 hours were pretreated by further drying at 80°C for 6 hours in vacuum (approximately 0.5 kPa) to prepare a sample for measuring the glass transition temperature.

[0141] Approximately 5 mg of the pretreated measurement sample was weighed and placed in an aluminum hermetic pan. An empty aluminum hermetic pan was used as a reference, and measurements were performed under conditions appropriate for the type (material) of polymer particles in each example. The measurement device used was a differential scanning calorimeter "Discovery DSC2500" (manufactured by TA Instruments).

[0142] Regarding the polymer particles, polymethyl methacrylate (PMMA) or a copolymer of styrene monomer and methyl methacrylate (MMA), the glass transition temperature (Tg) was measured under the following conditions. The measurement temperature range was 30°C to 250°C, and the sample was heated from 30°C to 250°C at a rate of 10°C / min, then held at that temperature for 1 minute, and then cooled from 250°C to 30°C at a rate of 10°C / min, and held at that temperature for 1 minute. The sample was then heated again to 250°C at a rate of 10°C / min, and the midpoint glass transition temperature (Tmg) was taken as the glass transition temperature (Tg).

[0143] Of the polymer particles, the glass transition temperature (Tg) of polybutyl methacrylate (PBMA) was measured under the following conditions. The measurement temperature range was -40°C to 250°C, and the sample was heated from -40°C to 250°C at a heating rate of 10°C / min, then held at that temperature for 1 minute, and then cooled from 250°C to -40°C at a heating rate of 10°C / min, and held at that temperature for 1 minute. The sample was again heated to 250°C at a heating rate of 10°C / min, and the midpoint glass transition temperature (Tmg) was taken as the glass transition temperature (Tg).

[0144] For polymethyl acrylate (PMA) among the polymer particles, the glass transition temperature (Tg) is measured under the following conditions. The measurement temperature range was -40°C to 300°C, and the sample was heated from -40°C to 300°C at a heating rate of 10°C / min, then held at that temperature for 1 minute, and then cooled from 300°C to -40°C at a cooling rate of 10°C / min, and held at that temperature for 1 minute. The sample was again heated to 300°C at a heating rate of 10°C / min, and the midpoint glass transition temperature (Tmg) was taken as the glass transition temperature (Tg).

[0145] Regarding the polymer particles, polystyrene or a copolymer of styrene monomer and methyl acrylate (MA), the glass transition temperature (Tg) was measured under the following conditions. The measurement temperature range was 30°C to 300°C, and the sample was heated from 30°C to 300°C at a heating rate of 10°C / min, then held at that temperature for 1 minute, and then cooled from 300°C to 30°C at a cooling rate of 10°C / min, and held at that temperature for 1 minute. The sample was again heated to 300°C at a heating rate of 10°C / min, and the midpoint glass transition temperature (Tmg) was taken as the glass transition temperature (Tg).

[0146] [Volume average particle size (D50)] The volume average particle size (D50) was measured using reagent-grade methanol (solvent refractive index: 1.33) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the dispersion solvent, dispersing the particles for 5 minutes (output: 25 W) using the device's built-in ultrasonic homogenizer, and measuring the volume average particle size (D50) using a Microtrac MT3300EXII (a particle size distribution analyzer manufactured by Microtrac) at a circulation speed of 50% (65 mL / sec at 100%) under concentration conditions within the appropriate range of the device's Loading Index.

[0147] <Forming method> To evaluate the molded articles obtained using the polymer particles of each example, pellet-shaped resin compositions were prepared under the following conditions, and molded articles were obtained using the obtained pellet-shaped resin compositions by compression molding for polymethyl methacrylate (PMMA) among the polymer particles and injection molding for the other polymer particles. The specific preparation method and molding conditions for the pellet-shaped resin compositions are as follows:

[0148] [Preparation of pellet-shaped resin composition] First, in each example, polymer particles obtained by drying at 70°C for 12 hours were subjected to a pretreatment of further drying at 80°C for 6 hours in vacuum (approximately 0.5 kPa). The pretreated polymer particles of each example were fed from the hopper of a Parker Corporation co-rotating twin-screw extruder HK-25D (41D) (screw diameter: φ25 mm, L / D=41) using a twin-screw feeder, and a pellet-shaped resin composition was obtained after kneading and extrusion. The screw rotation speed was 100 rpm, the kneading temperature was 230°C, and the torque was 55–60 N·m.

[0149] The kneading temperature was 230°C for the polymer particles of polymethyl methacrylate (PMMA), 150°C for the polymer particles of polymethyl acrylate (PMA) and polybutyl methacrylate (PBMA), 230°C for the polymer particles of polystyrene (PST), and 200°C for the polymer particles of copolymers of styrene monomer (ST) and methyl methacrylate (MMA) (P(ST-MMA)) and copolymers of styrene monomer (ST) and methyl acrylate (MA) (P(ST-MA)).

[0150] [Compression molding method] The resulting pelletized resin composition was molded using a 70t automatic press manufactured by Oji Kikai Co., Ltd. to obtain a plate-shaped molded sample having a thickness of 4.0 mm. The pressure pressing conditions were a molding temperature (set temperature) of 270°C, a preheating time of 6 minutes, a pressure rise time of 10 seconds, a pressure time of 1 minute, and a gauge pressure of 20 MPa. The cooling pressing conditions were a set temperature of 23°C, a cooling time of 1 minute, and a gauge pressure of 20 MPa. A fluorine-based mold release agent (FC-252 manufactured by Fine Chemical Japan Co., Ltd.) was used as the mold release agent.

[0151] [Injection molding method] The resulting pelletized resin composition was molded using an electric injection molding machine NEX140 III (injection type 25E, screw diameter: φ40 mm) manufactured by Nissei Plastic Industrial Co., Ltd., to obtain a flat plate-shaped molded sample having a thickness of 4.0 mm. The screw rotation speed was 150 rpm, and the kneading temperature was 230°C for the pellet-shaped resin composition of polymethyl methacrylate (PMMA), 150°C for the pellet-shaped compositions of polymethyl acrylate (PMA) and polybutyl methacrylate (PBMA), 230°C for the pellet-shaped composition of polystyrene (PST), and 200°C for the pellet-shaped compositions of a copolymer of styrene monomer (ST) and methyl methacrylate (MMA) (P(ST-MMA)) and a copolymer of styrene monomer (ST) and methyl acrylate (MA) (P(ST-MA)).

[0152] <Methods for measuring and evaluating molded products> The physical properties of the molded articles of each example were measured and evaluated by the following methods.

[0153] [Water absorption rate] The above-mentioned 4.0 mm thick flat molded samples were cut into square test pieces with length and width of 61 ± 1 mm. Using the obtained test pieces, the water absorption of each molded sample was measured in accordance with Method A (excluding immersion temperature and immersion time) specified in the international standard ISO 62:1999 for plastic materials (Plastics - Determination of water absorption). The immersion temperature in distilled water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was 37°C, and the immersion time was 48 hours.

[0154] [Oil absorption rate] The oil absorption rate of each molded body sample was measured in the same manner as the water absorption rate, except that a mixture of oleic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and linoleic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in the same volume ratio was used instead of distilled water.

[0155] [Surface dissipation energy limit] Among the molded specimens in each example, the surface dissipation energy limit value (G IC The bending strength (Single-edge-notch-bending value) was measured by the SENB (Single-edge-notch-bending) method specified in the American standard for plastic materials, ASTM D5045-14. The test speed was 10 mm / min.

[0156] <Raw materials> The raw materials used in each of the examples and comparative examples are as follows. [Polymerizable monomer] MMA: Methyl methacrylate (methyl methacrylate), manufactured by Mitsubishi Chemical Corporation, product name "Acryester (registered trademark) M." MA: Methyl acrylate (special grade), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. BMA: Butyl methacrylate (butyl methacrylate) (special grade), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0157] ST: Styrene monomer (special grade) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., which was pretreated to remove the polymerization inhibitor. The pretreatment was carried out as follows. First, 100 parts by volume of styrene monomer (special grade) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. and 100 parts by volume of 0.1 M aqueous sodium hydroxide solution were placed in a separatory funnel and shaken for 5 minutes using a powerful shaker for separatory funnels, the Strong Shaker "SR-2EW" manufactured by Taitec Co., Ltd. The shaking speed was 60 rpm, and the styrene monomer phase was removed. The above procedure was repeated twice and the resulting mixture was used in each of the Examples and Comparative Examples. Note that no aqueous phase was mixed into the styrene monomer used in each of the Examples and Comparative Examples.

[0158] [Polymerization initiator] In Examples 1 to 39 and Comparative Examples 1 to 26, a mixture of 85 mass% partially oxidized tributylboron and 15 mass% ethanol (manufactured by Mitsui Chemicals, Inc., product name "BC-S1i") (the total amount of the polymerization initiator is taken as 100 mass%) was used as the polymerization initiator. "BC-S[a]i" (where [a] represents any integer between 0 and 99) refers to medical bone cement manufactured by Mitsui Chemicals, Inc., product name "JOINEXUS (registered trademark) Bone Cement R" (bone cement for artificial joint fixation), product name "JOINEXUS (registered trademark) Bone Cement V" (bone cement for percutaneous vertebroplasty (PVP), bone cement for percutaneous balloon kyphoplasty (BKP), and bone cement for percutaneous vertebroplasty with vertebral stent (VBS)), or a component of some of Mitsui Chemicals' medical devices for orthopedic use.

[0159] In Example 40 and Comparative Example 27, 100% by mass of partially oxidized tributylboron (manufactured by Mitsui Chemicals, Inc., "TBBO") (the total amount of the polymerization initiator is taken as 100% by mass) was used. In Example 41 and Comparative Example 28, a mixture of 51 mass % partially oxidized tributylboron and 49 mass % ethanol (manufactured by Mitsui Chemicals, Inc., product name "BC-S2i") (the total amount of the polymerization initiator is taken as 100 mass %) was used.

[0160] In Example 42 and Comparative Example 29, a mixture of 80% by mass of partially oxidized tributylboron, 19% by mass of n-hexane, and 1% ethanol (manufactured by Mitsui Chemicals, Inc., product name "BC-S1006ikoa") (the total mass of the polymerization initiator is taken as 100% by mass) was used. "BC-S[b]ikoa" (where [b] represents an integer between 1000 and 1009) is a component of the medical adhesive manufactured by Mitsui Chemicals, Inc., product name "EPINEXUS (registered trademark)."

[0161] [Dispersant] Na2HPO4: Disodium hydrogen phosphate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. K2HPO4: Manufactured by FUJIFILM Wako Pure Chemical Corporation, dipotassium hydrogen phosphate. Na4P2O4: Manufactured by Taihei Chemical Industry Co., Ltd., sodium pyrophosphate. Na3PO4: Manufactured by Taihei Chemical Industry Co., Ltd., sodium phosphate dodecahydrate. Na2HPO3: Manufactured by Taihei Chemical Industry Co., Ltd., sodium hydrogen phosphite pentahydrate.

[0162] KI: Manufactured by FUJIFILM Wako Pure Chemical Corporation, potassium iodide. NaF: Manufactured by FUJIFILM Wako Pure Chemical Corporation, sodium fluoride. TBAF: Manufactured by FUJIFILM Wako Pure Chemical Corporation, tetra-n-butylammonium fluoride trihydrate. TBACl: Manufactured by Tokyo Chemical Industry Co., Ltd., tetra-n-butylammonium chloride. TBAI: Manufactured by Tokyo Chemical Industry Co., Ltd., tetra-n-butylammonium iodide.

[0163] NaCl: Manufactured by FUJIFILM Wako Pure Chemical Corporation, sodium chloride. MgCl2: Manufactured by FUJIFILM Wako Pure Chemical Corporation, magnesium chloride. C2H6O2: Manufactured by FUJIFILM Wako Pure Chemical Corporation, ethylene glycol. SDS: Manufactured by FUJIFILM Wako Pure Chemical Corporation, sodium dodecyl sulfate (CH3(CH2) 11 OSO3Na). PVA: Manufactured by Denka Co., Ltd., polyvinyl alcohol, product name "Denka Poval (registered trademark) B-20".

[0164] <Examples and Comparative Examples of PMMA (Organic Boron-Based Polymerization Initiator: BC-S1i)> [Example 1] Into a reactor (four-necked round-bottom flask) equipped with a stirrer, a cooling tube, and a thermometer, 4960 parts by mass of purified water (manufactured by FUJIFILM Wako Pure Chemical Corporation), 10 parts by mass of PVA, and 2.4 parts by mass of Na2HPO4 were added and stirred to dissolve PVA and Na2HPO4 to form an aqueous phase (continuous phase). Furthermore, 45 parts by mass of an organoboron-based polymerization initiator (including parts by mass of ethanol) was added to 890 parts by mass of MMA to form an oil phase (dispersed phase). Because organoboron-based polymerization initiators have the property of denaturing and losing their polymerization activity when in contact with oxygen (air), the oil phase was prepared under a nitrogen atmosphere.

[0165] While stirring the aqueous phase at 300 rpm with a stirring blade, the entire amount of the oil phase was added dropwise to the reactor using a dropping funnel over about 10 minutes to prepare a suspension. Thereafter, while continuing stirring, the temperature inside the reaction system was raised to 60° C. While continuing stirring, the temperature was maintained at 60° C. for 6 hours to carry out suspension polymerization, and then the mixture was cooled to room temperature (about 23° C.). During the preparation of the suspension and the polymerization, nitrogen gas was supplied to the reactor at a rate of 1 L / min to create a nitrogen atmosphere.

[0166] After the suspension polymerization was completed, the polymer particles and the aqueous medium were removed from the reactor and separated using a filter, etc. Since the aqueous medium was still attached to the surface of the polymer particles immediately after separation, the polymer particles were thoroughly washed with purified water to completely remove the attached aqueous medium, and then dried at 70°C for 12 hours using a dryer to obtain polymethyl methacrylate (PMMA) polymer particles of Example 1. Furthermore, a pellet-shaped resin composition was prepared using the obtained polymer particles, and the pellet-shaped resin composition was compression molded to obtain a molded article of Example 1.

[0167] [Examples 2 to 7, Comparative Examples 1 to 5] Polymer particles (PMMA) of each example were obtained in the same manner as in Example 1, except that a dispersant shown in Table 1 was blended in the amount shown in Table 1 instead of 2.4 parts by mass of NaHPO and PVA was used to prepare an aqueous phase. Also, molded bodies of each example were obtained in the same manner as in Example 1. Table 1 shows the polymer particles obtained in each example and the physical properties and evaluation results of the molded products obtained from the polymer particles.

[0168] [Table 1]

[0169] As shown in Table 1, the polymer particles of Examples 1 to 7, which used the specific dispersant, had a lower B content, a higher molecular weight, and a higher glass transition temperature Tg than the polymer particles of Comparative Examples 1 to 5. Furthermore, the molded articles obtained from the polymer particles of Examples 1 to 7 had lower water absorption and oil absorption than the molded articles obtained from the polymer particles of Comparative Examples 1 to 5. IC The value was high.

[0170] [Example 8] Except for preparing the aqueous phase by blending 10 parts by mass of PVA and 31 parts by mass of NaHPO instead of 2.4 parts by mass of NaHPO, polymer particles (PMMA) of Example 8 were obtained in the same manner as in Example 1. Furthermore, a pellet-shaped resin composition was prepared using the obtained polymer particles, and the pellet-shaped resin composition was compression molded to obtain a molded product of Example 8.

[0171] [Examples 9 to 12, Comparative Examples 6 to 9] Polymer particles (PMMA) of each example were obtained in the same manner as in Example 8, except that the aqueous phase (continuous phase) was prepared by blending the dispersant shown in Table 2 in the amount shown in Table 2 instead of 31 parts by mass of NaHPO. Also, molded bodies of each example were obtained in the same manner as in Example 8. Table 2 shows the polymer particles obtained in each example and the physical properties and evaluation results of the molded products obtained from the polymer particles.

[0172] [Table 2]

[0173] As shown in Table 2, the polymer particles of Examples 8 to 12, which used a specific dispersant without using PVA, had a lower B content, a higher molecular weight, and a higher glass transition temperature Tg than the polymer particles of Comparative Examples 6 to 8. Furthermore, the molded articles obtained from the polymer particles of Examples 8 to 12 had lower water absorption and oil absorption than the molded articles obtained from the polymer particles of Comparative Examples 6 to 8. IC The value was high. In Comparative Example 9, polymer particles were not obtained.

[0174] <Examples and Comparative Examples of PMA (Organic Boron-based Polymerization Initiator: BC-S1i)> [Example 13] Into a reactor (four-neck round-bottom flask) equipped with a stirrer, a cooling tube, and a thermometer, 4960 parts by mass of purified water (manufactured by Fujifilm Wako Pure Chemical Corporation), 10 parts by mass of PVA, and 2.4 parts by mass of Na2HPO4 were placed and stirred to dissolve PVA and Na2HPO4 to form an aqueous phase (continuous phase). Also, under a nitrogen atmosphere, 20 parts by mass of an organic boron-based polymerization initiator (including the parts by mass of ethanol) was added to 900 parts by mass of MA to form an oil phase (dispersed phase). Polymer particles of polymethyl acrylate (PMA) were obtained in the same manner as in Example 1, except that the obtained aqueous phase and oil phase were used. Also, a pellet-shaped resin composition was prepared using the obtained polymer particles, and further, the pellet-shaped resin composition was injection-molded to obtain a molded body of Example 13.

[0175] [Examples 14 to 17, Comparative Examples​​​​​​​​​​​​​​​​​​​

[0178] <Examples and Comparative Examples of PBMA (Organic Boron-Based Polymerization Initiator: BC-S1i)> [Example 18] Into a reactor (four-neck round-bottom flask) equipped with a stirrer, a cooling tube, and a thermometer, 4960 parts by mass of purified water (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), 10 parts by mass of PVA, and 2.2 parts by mass of Na2HPO4 were added and stirred to dissolve PVA and Na2HPO4 to form an aqueous phase (continuous phase). Also, under a nitrogen atmosphere, 45 parts by mass of an organic boron-based polymerization initiator (including parts by mass of ethanol) was added to 900 parts by mass of BMA to form an oil phase (dispersion phase). Polymer particles of polybutyl methacrylate (PBMA) of Example 18 were obtained in the same manner as in Example 1, except that the obtained aqueous phase and oil phase were used. Also, a pelletized resin composition was prepared using the obtained polymer particles, and further, the pelletized resin composition was injection-molded to obtain a molded body of Example 18.

[0179] [Examples 19 to 21, Comparative Examples 14 to 17] Polymer particles of each example were obtained in the same manner as in Example 18, except that the dispersant shown in Table 4 was blended in the amount shown in Table 4 instead of 2.2 parts by mass of Na2HPO4 to prepare an aqueous phase together with PVA. Also, molded bodies of each example were obtained in the same manner as in Example 18.

[0180] [Table 4]

[0181] As shown in Table 4, the polymer particles of Examples 18 to 21 using a specific dispersant had a lower B content, a higher molecular weight, and a higher glass transition temperature Tg compared to the polymer particles of Comparative Examples 14, 15, and 17. Also, the molded bodies obtained from the polymer particles of Examples 18 to 21 had a lower water absorption rate and oil absorption rate compared to the molded bodies obtained from the polymer particles of Comparative Examples 14, 15, and 17. Note that no polymer particles were obtained in Comparative Example 16.

[0182] <Examples and Comparative Examples of PST (Organic Boron-based Polymerization Initiator: BC-S1i)> [Example 22] Into a reactor (four-necked round-bottom flask) equipped with a stirrer, a cooling tube, and a thermometer, 4960 parts by mass of purified water (manufactured by Fujifilm Wako Pure Chemical Corporation), 10 parts by mass of PVA, and 2.4 parts by mass of Na2HPO4 were added and stirred to dissolve PVA and Na2HPO4 to form an aqueous phase (continuous phase). Also, under a nitrogen atmosphere, 50 parts by mass of an organic boron-based polymerization initiator (including the mass part of ethanol) was added to 880 parts by mass of ST to form an oil phase (dispersion phase). Polymer particles of polystyrene (PST) of Example 22 were obtained in the same manner as in Example 1 except that the obtained aqueous phase and oil phase were used. The suspension polymerization time was 120 hours. Also, a pellet-shaped resin composition was prepared using the obtained polymer particles, and further, the pellet-shaped resin composition was injection-molded to obtain a molded body of Example 22.

[0183] [Examples 23 to 28, Comparative Examples 18 to 20] Polymer particles of each example were obtained in the same manner as in Example 22 except that the dispersant described in Table 5 was blended in the amount described in Table 5 instead of 2.4 parts by mass of Na2HPO4 to prepare an aqueous phase together with PVA. Also, molded bodies of each example were obtained in the same manner as in Example 22.

[0184] [Table 5]

[0185] As shown in Table 5, the polymer particles of Examples 22 to 28 using a specific dispersant had a lower B content, a higher molecular weight, and a higher glass transition temperature Tg compared to the polymer particles of Comparative Examples 18 to 20. Also, the molded bodies obtained from the polymer particles of Examples 22 to 28 had a lower water absorption rate and oil absorption rate compared to the molded bodies obtained from the polymer particles of Comparative Examples 18 to 20.

[0186] <Examples and Comparative Examples of P(ST-MMA) (Organoboron Polymerization Initiator: BC-S1i)> [Example 29] Into a reactor (four-necked round-bottom flask) equipped with a stirrer, a cooling pipe, and a thermometer, 4960 parts by mass of purified water (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), 10 parts by mass of PVA, and 2.4 parts by mass of Na2HPO4 were placed and stirred to dissolve PVA and Na2HPO4 to form an aqueous phase (continuous phase). Also, under a nitrogen atmosphere, 45 parts by mass of an organoboron polymerization initiator (including parts by mass of ethanol) were added to 440 parts by mass of MMA and 420 parts by mass of ST to form an oil phase (dispersion phase). Polymer particles of a copolymer (P(ST-MMA)) of styrene monomer (ST) and methyl methacrylate (MMA) of Example 29 were obtained in the same manner as in Example 1 except that the obtained aqueous phase and oil phase were used.

[0187] [Examples 30 to 33, Comparative Examples 21 to 23] Polymer particles of each example were obtained in the same manner as in Example 29 except that the dispersants described in Table 6 were blended in the amounts described in Table 6 instead of 2.4 parts by mass of Na2HPO4 to prepare an aqueous phase together with PVA. Also, molded bodies of each example were obtained in the same manner as in Example 29.

[0188] [Table 6]

[0189] As shown in Table 6, the polymer particles of Examples 29 to 33 using a specific dispersant had a lower B content, a higher molecular weight, and a higher glass transition temperature Tg compared to the polymer particles of Comparative Examples 21 to 23. Also, the molded bodies obtained from the polymer particles of Examples 29 to 33 had a lower water absorption rate and oil absorption rate compared to the molded bodies obtained from the polymer particles of Comparative Examples 21 to 23. '

[0190] <Examples and Comparative Examples of P(ST-MA) (Organoboron Polymerization Initiator: BC-S1i)>[[ID= 33]] [Example 34] Into a reactor (four-neck round-bottom flask) equipped with a stirrer, a cooling pipe, and a thermometer, 4960 parts by mass of purified water (manufactured by Fujifilm Wako Pure Chemical Corporation), 10 parts by mass of PVA, and 2.5 parts by mass of Na2HPO4 were added and stirred to dissolve PVA and Na2HPO4 to form an aqueous phase (continuous phase). Also, under a nitrogen atmosphere, 45 parts by mass of an organoboron-based polymerization initiator (including parts by mass of ethanol) was added to 440 parts by mass of MA and 420 parts by mass of ST to form an oil phase (dispersion phase). Polymer particles of a copolymer (P(ST-MA)) of styrene monomer (ST) and methyl acrylate (MA) of Example 34 were obtained in the same manner as in Example 1 except that the obtained aqueous phase and oil phase were used. Also, a pellet-shaped resin composition was prepared using the obtained polymer particles, and further, the pellet-shaped resin composition was injection-molded to obtain a molded body of Example 34.

[0191] [Examples 35 to 39, Comparative Examples 24 to 26] Polymer particles of each example were obtained in the same manner as in Example 34 except that the dispersant described in Table 7 was blended in the amount described in Table 7 instead of 2.5 parts by mass of Na2HPO4 to prepare an aqueous phase together with PVA. Also, molded bodies of each example were obtained in the same manner as in Example 34.

[0192]

Table 7

[0193] As shown in Table 7, the polymer particles of Examples 34 to 39 using a specific dispersant had a lower B content, a higher molecular weight, and a higher glass transition temperature Tg compared to the polymer particles of Comparative Examples Also, the molded bodies obtained from the polymer particles of Examples 34 to 39 had a lower water absorption rate and oil absorption rate compared to the molded bodies obtained from the polymer particles of Comparative Examples 24 to 26.

[0194] <Examples and Comparative Examples of PMMA (Organoboron-Based Polymerization Initiator: TBBO, BC-S2i or BC-S1006ikoa)> [Example 40] A reactor (four-neck round-bottom flask) equipped with a stirrer, a condenser, and a thermometer was charged with 4,960 parts by mass of purified water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 10 parts by mass of PVA, and 3.0 parts by mass of Na4P2O4, and the mixture was stirred to dissolve the PVA and Na4P2O4 and form an aqueous phase (continuous phase). Further, under a nitrogen atmosphere, 45 parts by mass of an organoboron-based polymerization initiator was added to 890 parts by mass of MMA to form an oil phase (dispersed phase). Polymer particles (PMMA) of Example 40 were obtained in the same manner as in Example 1, except that the obtained aqueous phase and oil phase were used. Furthermore, a pellet-shaped resin composition was prepared using the obtained polymer particles, and the pellet-shaped resin composition was compression molded to obtain a molded product of Example 40.

[0195] [Examples 41 to 42, Comparative Examples 27 to 29] Instead of 3.0 parts by mass of Na4P2O4, the dispersant shown in Table 8 was blended in the amount shown in Table 8 (including parts by mass of ethanol for Example 41 and Comparative Example 28, and including parts by mass of n-hexane and ethanol for Example 42 and Comparative Example 29), and the aqueous phase was prepared together with PVA. Except for this, polymer particles of each example were obtained in the same manner as in Example 40. Further, in the same manner as in Example 40, molded bodies of each example were obtained.

[0196] [Table 8]

[0197] As shown in Table 8, in Examples 40 to 42, in which a specific dispersant was used, the polymer particles obtained had a lower B content, a higher molecular weight, and a higher glass transition temperature Tg than the polymer particles of Comparative Examples 27 to 29, regardless of whether the organoboron-based polymerization initiator used was partially oxidized tributylboron itself without any alcohol or aprotic solvent added (Example 40), an organoboron-based polymerization initiator (BC-S2i) with a relatively large amount of alcohol added (Example 41), or an organoboron-based polymerization initiator (BC-S1006ikoa) with both alcohol and an aprotic solvent added (Example 42). Moreover, the molded articles obtained from the polymer particles of Examples 40 to 42 had lower water absorption and oil absorption than the molded articles obtained from the polymer particles of Comparative Examples 27 to 29. [Industrial Applicability]

[0198] According to the present invention, it is possible to provide polymer particles having a large molecular weight and a molded article having excellent durability properties such as toughness, heat resistance, oil resistance, and water resistance.

[0199] The polymer particles obtained by the production method of the present invention and the polymer particles of the present invention are useful as dental adhesive resin cements, which are used, for example, for molding and repairing cavities and defects in hard tissues such as teeth in the oral cavity, and for repairing and bonding artificial dental crowns.

[0200] The polymer particles obtained by the production method of the present invention and the polymer particles of the present invention are further useful as bone cement, a filler for bone defects, a bone substitute, and an artificial bone. Bone cement is used to bond hard tissues such as bones together, to fill the interior of hard tissues, to bond and / or adhere hard tissues to artificial materials such as titanium, ceramics, and stainless steel, to bond and / or adhere hard tissues to other tissues such as soft tissues, and to fix hard tissues such as bone and cartilage to artificial joints.

[0201] In addition, it is useful as a dressing material (wound covering material) to protect, (temporarily) cover, promote healing, or adhere wounds. Dressing materials are used by applying them to wounds caused by accidents or other factors in soft tissues such as skin, muscles, organs, and blood vessels of living organisms, i.e., the surface of severed tissue.

[0202] The polymer particles obtained by the production method of the present invention and the polymer particles of the present invention are also useful as constituent materials (raw materials) for medical materials (medical devices). Medical professionals, primarily physicians, can use the polymer particles obtained by the production method of the present invention and the polymer particles of the present invention as raw materials to prepare medical materials (medical devices) including implant materials or surgical materials just before use.

[0203] Furthermore, the molded article obtained by the production method of the present invention is useful as a cell culture vessel (material) such as a multi-plate. Furthermore, it is useful as a vertebral cage or vertebral fixation spacer used to fill the gap between upper and lower vertebrae in interbody fusion surgery in the treatment of degenerative diseases and trauma of the thoracic or lumbar vertebrae, such as herniated disc, spinal canal stenosis, and spinal compression fractures.

[0204] In addition, they are also useful as dental materials and implant scaffolds such as artificial teeth and dentures, dental composite resins, and denture bases for replacing damaged hard tissues or organs with healthy hard tissues or organs or restoring their functions, interbody fusion devices (materials) such as vertebral stents, bone spacers such as vertebral arch spacers, internal fixation devices (materials) used to fix fractures, etc. such as intramedullary nails, and materials for artificial organs such as artificial blood vessels.

Claims

1. A method for producing polymer particles by suspending an oil phase containing a polymerizable monomer and a polymerization initiator in an aqueous phase and carrying out suspension polymerization, comprising the steps of: the aqueous phase contains one or more selected from the group consisting of phosphorus oxoacids and salts thereof, alkali metal iodides, alkali metal fluorides, and quaternary ammonium salts; The method for producing polymer particles, wherein the polymerization initiator is an organic boron compound.

2. 2. The method for producing polymer particles according to claim 1, wherein the amount of the polymerization initiator is 1.0 to 15.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

3. The method for producing polymer particles according to claim 1, wherein the polymerizable monomer is at least one selected from the group consisting of (meth)acrylates and styrenes.

4. A method for producing a molded article, comprising obtaining polymer particles by the method for producing polymer particles according to any one of claims 1 to 3, and molding the obtained polymer particles.

5. The method for producing a molded article according to claim 4, wherein the molded article is a bioimplant material.

6. Polymer particles having a boron element content of 0.01% by mass or more and 0.30% by mass or less, based on the total mass of the polymer particles.

7. The polymer particles according to claim 6, wherein the polymer particles have units derived from one or more polymerizable monomers selected from the group consisting of (meth)acrylates and styrenes.

8. 8. The polymer particles according to claim 7, wherein the polymer particles are composed mainly of units derived from methyl methacrylate and have a weight average molecular weight (Mw) of 250,000 or more.

9. 8. The polymer particles according to claim 7, wherein the polymer particles are composed mainly of units derived from methyl acrylate and have a weight average molecular weight (Mw) of 1,200,000 or more.

10. 8. The polymer particles according to claim 7, wherein the polymer particles are composed mainly of units derived from butyl methacrylate and have a weight average molecular weight (Mw) of 140,000 or more.

11. 8. The polymer particles according to claim 7, wherein the polymer particles are composed mainly of units derived from methyl (meth)acrylate and styrene, and have a weight average molecular weight (Mw) of 300,000 or more.

12. 8. The polymer particles according to claim 7, wherein the polymer particles are composed mainly of units derived from styrene and have a weight average molecular weight (Mw) of 150,000 or more.

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