JP7354335B2 - polymer particles - Google Patents

Description

FIELD OF THE INVENTION This invention relates to polymer particles.

Polymer particles such as (meth)acrylic particles are widely used in various applications such as toner components, paint additives, optical materials, cosmetics, and molding resins.

Polymer particles are often used in combination with a base resin, and if the polymer particles have poor heat resistance, they will decompose due to heating during molding, and the molded product will have poor appearance and mechanical properties. Therefore, polymer particles are required to have excellent heat resistance.

One way to improve the heat resistance of (meth)acrylic polymer particles is to copolymerize a certain amount of acrylic monomer with methacrylic monomer. There was a problem in that the glass transition temperature (Tg) of the polymer particles was lower than in the case without it, leading to fusion between particles and a decrease in handling properties in the powder manufacturing process.

Another method for improving the heat resistance of (meth)acrylic polymer particles is to copolymerize a certain amount of a styrene monomer. Although this method can improve the heat resistance of the particles without causing problems such as fusion between particles during the manufacturing process, there is a problem of yellowing during heating.

For example, Patent Document 1 discloses a light-diffusing polycarbonate-based resin composition that has sufficient light-diffusing properties and light transmittance, exhibits little discoloration during molding, and has improved ability to prevent discoloration. Patent Document 1 proposes a light-diffusing polycarbonate resin composition comprising a polycarbonate resin and crosslinked (meth)acrylic polymer particles containing a phosphite antioxidant dispersed in the resin. has been done.

Japanese Patent Application Publication No. 2006-307140

Although it has been desired to improve the heat resistance of polymer particles, polymer particles with sufficient heat resistance have not yet been provided.

An object of the present invention is to provide polymer particles with excellent heat resistance (thermal decomposition resistance and heat yellowing resistance) that are suppressed from decomposition and yellowing when exposed to high temperatures.

As a result of intensive studies to solve the above problems, the present inventors found that polymer particles obtained by polymerizing specific monomer components in the presence of an antioxidant and thiosulfate have heat resistance ( The present invention was completed based on the discovery that the composition has excellent thermal decomposition resistance and thermal yellowing resistance.

That is, the present invention relates to, for example, the following [1] to [3].

[1] A method for producing polymer particles, in which a monomer component containing a styrenic monomer is polymerized in the presence of an antioxidant and a thiosulfate.

[2] The method for producing polymer particles according to [1], wherein the antioxidant is a phosphorous antioxidant.

[3] Polymer particles containing constituent components derived from monomer components containing styrene monomers, which satisfy the following conditions (i) and (ii).
(i) The YI value measured after heating the polymer particles at 150° C. for 1 hour in the atmosphere is 10 or less.
(ii) The polymer particles are heated at a rate of 10° C./min in a nitrogen atmosphere, and the weight loss rate when reaching 350° C. is 10% by weight or less.

By the method for producing polymer particles of the present invention, polymer particles having excellent heat resistance (thermal decomposition resistance and heat yellowing resistance) can be provided.

Next, the present invention will be specifically explained.

<Method for producing polymer particles>
In the method for producing polymer particles of the present invention, a monomer component containing a styrenic monomer is polymerized in the presence of an antioxidant and a thiosulfate.

The monomer component may contain a styrene monomer, and the content of the styrene monomer in 100% by mass of the monomer component is preferably 10 to 100% by mass, more preferably 15 to 80% by mass, particularly preferably It is in the range of 20 to 65% by mass.

Examples of styrenic monomers include styrene; alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; fluorostyrene; , chlorostyrene, bromostyrene, dibromostyrene, chloromethylstyrene, and halogenated styrenes such as iodized styrene; nitrostyrene; acetylstyrene; methoxystyrene, and the like. As the styrene monomer, one type may be used alone, or two or more types may be used.

The monomer component may contain monomers other than styrene monomers, and examples of monomers other than styrene monomers include (meth)acrylic acid alkyl esters, which are vinyl monomers, Polyfunctional monomers having three or more ethylenically unsaturated groups, alkoxyalkyl (meth)acrylates, alkoxypolyalkylene glycol (meth)acrylates, monomers containing functional groups, (meth)acrylates containing alicyclic groups or aromatic rings, vinyl acetate etc. Monomers other than styrene monomers may be used alone or in combination of two or more.

The content of monomers other than styrene monomers in 100% by mass of the monomer components is preferably in the range of 0 to 90% by mass, more preferably 20 to 85% by mass, particularly preferably 35 to 80% by mass.

In addition, in this specification, "(meth)acrylic" means acrylic or methacrylic, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryloyl" means acryloyl or methacryloyl. means.

((meth)acrylic acid alkyl ester)
In the present invention, it is preferable to use a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 18 carbon atoms as a monomer component other than the styrene monomer. The number of carbon atoms in the alkyl group is preferably 1 to 12, more preferably 1 to 10, particularly preferably 1 to 8.

Examples of (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 18 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl ( meth)acrylate, isobutyl(meth)acrylate, tert-butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, octyl(meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, stearyl ( Examples include meth)acrylate and isostearyl (meth)acrylate. These may be used alone or in combination of two or more.

The content of (meth)acrylic acid alkyl ester in 100% by mass of monomer components is not particularly limited, but is usually 0 to 90% by mass, preferably 15 to 80% by mass, more preferably 30 to 75% by mass. % range.

(polyfunctional monomer)
In the present invention, it is preferable to use a polyfunctional monomer having two or more ethylenically unsaturated groups in one molecule as the monomer component. The number of ethylenically unsaturated groups in one molecule of the polyfunctional monomer is preferably 2 to 8, more preferably 2 to 6.

Examples of polyfunctional monomers having two or more ethylenically unsaturated groups in one molecule include ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, Tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, modified bisphenol A di(meth)acrylate, tricyclodecane dimethanol Di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxytri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethylene oxide modified trimethylolpropane tri(meth)acrylate, propylene oxide modified trimethylolpropane Tri(meth)acrylate, glycerin propoxytri(meth)acrylate, tris(acryloxyethyl)isocyanurate, caprolactone-modified tris(acryloxyethyl)isocyanurate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate , pentaerythritol ethoxytetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, propionic acid modified dipentaerythritol penta(meth)acrylate, alkyl modified dipentaerythritol penta(meth)acrylate ) acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, divinylbenzene, and other polyfunctional monomers. These may be used alone or in combination of two or more.

The content of the polyfunctional monomer having two or more ethylenically unsaturated groups in one molecule in 100% by mass of the monomer component is usually 0 to 15% by mass, preferably 0.1 to 10% by mass, and more preferably is in the range of 0.5 to 8% by mass. When the amount of the polyfunctional monomer having two or more ethylenically unsaturated groups in one molecule is within the above range, a polymer having an appropriate degree of crosslinking, high molecular weight, and excellent heat resistance and solvent resistance can be obtained. This is preferable in that coalesced particles can be obtained.

(Alkoxyalkyl (meth)acrylate)
In the present invention, alkoxyalkyl (meth)acrylate may be used as a monomer component.

Examples of alkoxyalkyl (meth)acrylates include methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, and 3-ethoxypropyl (meth)acrylate. Examples include meth)acrylate, 4-methoxybutyl(meth)acrylate, and 4-ethoxybutyl(meth)acrylate.

(Alkoxypolyalkylene glycol (meth)acrylate)
In the present invention, alkoxy polyalkylene glycol (meth)acrylate may be used as the monomer component.

Examples of alkoxy polyalkylene glycol (meth)acrylates include methoxydiethylene glycol mono(meth)acrylate, methoxydipropylene glycol mono(meth)acrylate, ethoxytriethylene glycol mono(meth)acrylate, ethoxydiethylene glycol mono(meth)acrylate, and methoxydiethylene glycol mono(meth)acrylate. Triethylene glycol mono(meth)acrylate is mentioned.

(Functional group-containing monomer)
In the present invention, a functional group-containing monomer may be used as a monomer component.

Examples of functional group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl. Hydroxyl group-containing monomers such as (meth)acrylate; β-carboxyethyl (meth)acrylate, 5-carboxypentyl (meth)acrylate, mono(meth)acryloyloxyethyl succinate, ω-carboxypolycaprolactone mono(meth) Carboxyl group-containing monomers such as acrylate, acrylic acid, and methacrylic acid; Glycidyl group-containing monomers such as allyl glycidyl ether and glycidyl (meth)acrylate; Amino group-containing monomers such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate ; Examples include amide group-containing monomers such as (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, and N-hexyl (meth)acrylamide.

(Alicyclic group or aromatic ring-containing (meth)acrylate)
In the present invention, an alicyclic group or an aromatic ring-containing (meth)acrylate may be used as the monomer component.

Examples of alicyclic group- or aromatic ring-containing (meth)acrylates include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate. .

The above alkoxyalkyl (meth)acrylate, alkoxypolyalkylene glycol (meth)acrylate, functional group-containing monomer, alicyclic group or aromatic ring-containing (meth)acrylate may be used alone or in combination of two or more. May be used.

In 100% by mass of monomer components, the total content of alkoxyalkyl (meth)acrylate, alkoxypolyalkylene glycol (meth)acrylate, functional group-containing monomer, alicyclic group or aromatic ring-containing (meth)acrylate is usually 10% by mass. % or less, preferably 8% by mass or less, more preferably 5% by mass or less.

(Antioxidant)
In producing the (meth)acrylic polymer particles of the present invention, the above-mentioned monomer components are polymerized in the presence of an antioxidant and a thiosulfate.

Examples of antioxidants include phosphorus-based antioxidants, phenolic antioxidants, amine-based antioxidants, sulfur-based antioxidants, etc., but from the viewpoint of effectively suppressing yellowing when exposed to high temperatures. Therefore, it is preferable to use a phosphorous antioxidant.

Examples of phosphorus antioxidants include tris(2,5-di-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris[2,4-bis(1, 1-dimethylpropyl)phenyl]phosphite, tris(mono- or di-tert-butylphenyl)phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecylphosphite) ), cyclic neopentane tetrayl bis(2,6-di-t-butyl-4-methylphenyl phosphite), tris(nonylphenyl) phosphite, 2-ethylhexyldiphenyl phosphite, diphenylisodecyl phosphite , triisodecyl phosphite, triphenyl phosphite, 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecene, 2,2'- Methylenebis(4,6-di-tert-butylphenyl)-2-ethylhexylphosphite, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8, Examples include 10-tetraoxa-3,9-diphosphaspiro[5,5]undecane (ADEKA STAB PEP-36: manufactured by ADEKA).

Examples of phenolic antioxidants include α-tocopherol, 4-methoxyphenol, 4-hydroxyphenyl (meth)acrylate, β-tocopherol, 2,6-di-tert-butylphenol, 2,6-di-tert-4- Methoxyphenol, 2-tert-butyl-4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, Stearyl-β-propionate (3. 5-di-tert-butyl-4-hydroxyphenyl) and the like.

Examples of amine antioxidants include octylated diphenylamine, dicumyldiphenylamine, N-phenyl-1-naphthylamine, 2,2'-diethyl-4-nonyldiphenylamine and 2,2'-diethyl-4,4'-dinonyl. Examples include mixtures with diphenylamine.

Sulfur-based antioxidants include thiodipropionic acid, dilaurylthiodipropionate, distearylthiodipropionate, laurylstearylthiodipropionate, dimyristylthiodipropionate, distearyl-β,β'-thio Dibutyrate, thiobis(β-naphthol), thiobis(N-phenyl-β-naphthylamine, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel diptyldithiocarbamate, etc.) can be mentioned.

The antioxidants may be used alone or in combination of two or more.

The antioxidant is preferably used in an amount of 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, per 100 parts by weight of the monomer components.

(thiosulfate)
In producing the (meth)acrylic polymer particles of the present invention, the above-mentioned monomer components are polymerized in the presence of an antioxidant and a thiosulfate.

Examples of the thiosulfate include sodium thiosulfate, ammonium thiosulfate, potassium thiosulfate, and calcium thiosulfate, with sodium thiosulfate being preferred.

One type of thiosulfate may be used alone, or two or more types may be used.

The thiosulfate is preferably used in an amount of 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, per 100 parts by weight of the monomer components.

In the present invention, polymer particles obtained by polymerizing monomer components including styrenic monomers in the presence of an antioxidant and thiosulfate decompose and yellow when exposed to high temperatures. It's difficult. That is, the polymer particles obtained by the production method of the present invention have excellent heat resistance (thermal decomposition resistance and heat yellowing resistance). Although the reason for this is not clear, the present inventors believe that the polymer particles obtained by the production method of the present invention have excellent heat resistance due to the improved active radical scavenging ability due to the synergistic effect of thiosulfate and antioxidant. estimated.

(manufacturing conditions)
In the method for producing polymer particles of the present invention, a monomer component containing a styrenic monomer is polymerized in the presence of an antioxidant and a thiosulfate.

In the production method of the present invention, the monomer component may be polymerized in the presence of an antioxidant and a thiosulfate, and the polymerization method is not particularly limited, but examples include solution polymerization, bulk polymerization, emulsification. It can be produced by conventionally known polymerization methods such as polymerization and suspension polymerization.

As a specific polymerization method, for example, a polymerization solvent or dispersion medium and monomer components are charged into a reaction vessel, a polymerization initiator is added under an inert gas atmosphere such as nitrogen gas, and the reaction initiation temperature is usually set at 40 to 100°C. , preferably at 50 to 90°C, and maintaining the reaction system at a temperature of usually 50 to 90°C, preferably 60 to 90°C, and reacting for 1 to 20 hours, preferably 1 to 5 hours, to form a polymer. particles can be obtained.

Examples of the polymerization initiator include azo initiators and peroxide polymerization initiators.

Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2- cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carboxylic acid), nitrile), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'- Azobis(N,N'-dimethyleneisobutyramidine), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(isobutyramide) dihydrate, 4 , 4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-cyanopropanol), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis( Examples include azo compounds such as 2-methyl-N-(2-hydroxyethyl)propionamide) and 2,2'-azobis(2-amidinopropane) dihydrochloride.

Examples of peroxide-based polymerization initiators include organic peroxides and persulfates.

Examples of organic peroxides include t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, and dicumyl peroxide. -2-ethylhexyl peroxydicarbonate, t-butyl peroxybivalate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-bis(4,4-di- t-amylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-octylperoxycyclohexyl)propane, 2,2-bis(4,4-di-α-cumylperoxycyclohexyl)propane , 2,2-bis(4,4-di-t-butylperoxycyclohexyl)butane, and 2,2-bis(4,4-di-t-octylperoxycyclohexyl)butane.

Examples of persulfates include ammonium persulfate, potassium persulfate, sodium persulfate, and the like.

One type of polymerization initiator may be used alone, or two or more types may be used in combination. Furthermore, there is no restriction on adding the polymerization initiator multiple times during polymerization.

The polymerization initiator is used in an amount usually in the range of 0.001 to 5 parts by weight, preferably 0.005 to 3 parts by weight, based on 100 parts by weight of the monomer components.

Further, in the production method of the present invention, a polymerization initiator, a chain transfer agent, a monomer component, and a polymerization solvent may be additionally added as appropriate during the polymerization reaction.

Examples of the dispersion medium include aqueous media. In the present invention, the aqueous medium means water or a medium containing water as a main component. Specifically, water alone or a mixture of water and a lower alcohol such as methanol or ethanol may be used, and among these, water alone is preferable. The amount of the aqueous medium to be used is not particularly limited as it depends on the polymerization conditions, but is preferably 100 to 3000 parts by weight, more preferably 200 to 1000 parts by weight, based on 100 parts by weight of the monomer component.

A chain transfer agent may be used in the method for producing polymer particles of the present invention. Examples include chain transfer agents that do not contain polar groups, such as methyl mercaptan, n-dodecyl mercaptan, and α-methylstyrene dimer.

These thiol-based chain transfer agents may be used alone or in combination of two or more.

The amount of the chain transfer agent used is not particularly limited as it depends on the type of chain transfer agent and polymerization conditions, but is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 10 parts by weight per 100 parts by weight of the monomer components. It is 0.1 to 5 parts by mass.

In the method for producing polymer particles of the present invention, the obtained polymer particles are usually recovered after polymerization. As a method for recovering the polymer particles, conventionally known methods can be appropriately selected, and there are no particular limitations.

Since the polymer particles obtained by the production method of the present invention have excellent heat resistance (thermal decomposition resistance and heat yellowing resistance), they can be used as toner components, as additives for paints, as additives for films, as optical materials, It can be widely used in various applications such as cosmetics and molding resins.

<Polymer particles>
The polymer particles of the present invention are polymer particles containing components derived from monomer components containing styrenic monomers, and satisfy the following conditions (i) and (ii).

(i) The YI value measured after heating the polymer particles at 150° C. for 1 hour in the atmosphere is 10 or less.

(ii) The polymer particles are heated at a rate of 10° C./min in a nitrogen atmosphere, and the weight loss rate when reaching 350° C. is 10% by weight or less.

The polymer particles of the present invention have (i) a YI value of 10 or less, preferably 8 or less, measured after heating the polymer particles at 150° C. for 1 hour in the atmosphere.

The polymer particles of the present invention have (ii) a weight loss rate of 10% by weight or less when the polymer particles are heated at 10°C/min in a nitrogen atmosphere and the temperature reaches 350°C, preferably 0 to 8%. % by weight, more preferably 0 to 5% by weight.

Since the polymer particles of the present invention satisfy (i), they have excellent resistance to heat yellowing, and because they satisfy (ii), they have excellent heat decomposition resistance. Therefore, the polymer particles of the present invention can be widely used in various applications such as toner components, paint additives, optical materials, film additives, cosmetics, and molding resins. It is possible.

The polymer particles of the present invention have high heat-resistant decomposition properties because they contain constituent components derived from styrenic monomers. Furthermore, as the monomer component, it is preferable to use the monomer components described in the section <Method for producing polymer particles>.

The polymer particles of the present invention preferably contain an antioxidant and a thiosulfate from the viewpoint of heat resistance (thermal decomposition resistance and heat yellowing resistance). It is preferable that the antioxidant is a phosphorus antioxidant.

The average particle size of the polymer particles of the present invention is preferably 0.01 to 10,000 μm, more preferably 0.01 to 100 μm.

The polymer particles of the present invention are preferably produced by the method described in the above-mentioned <Method for producing polymer particles> because (i) and (ii) can be easily satisfied.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[Example 1]
59 parts by mass of MMA (methyl methacrylate), 40 parts by mass of St (styrene), 1 part by mass of EGDMA (ethylene glycol dimethacrylate), and antioxidant in a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet pipe. (ADEKA STAB PEP-36: manufactured by ADEKA) 0.2 parts by mass and 400 parts by mass of ion-exchanged water were charged, and the temperature was raised to 70° C. while introducing nitrogen gas.

Next, 0.3 parts by mass of potassium persulfate (KPS) and 0.3 parts by mass of sodium thiosulfate were added, and a polymerization reaction was carried out at 70° C. for 7 hours in a nitrogen atmosphere.

After cooling the reaction solution, it was filtered and dried to obtain polymer particles (A-1) with an average particle size of 0.4 μm.

[Example 2]
The same procedure as in Example 1 was carried out, except that 0.5 parts by mass of 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) was used instead of potassium persulfate (KPS) as a polymerization initiator. Polymer particles (A-2) having an average particle diameter of 0.4 μm were obtained.

[Comparative Examples 1 to 3]
The same procedure as in Example 1 was conducted except that the composition of each component used during polymerization was changed as shown in Table 1, and polymer particles (A'-1) to (A' -3) was obtained.

In addition, BA in Table 1 means n-butyl acrylate.

The weight loss rate, YI value, and average particle diameter of the polymer particles obtained in Examples and Comparative Examples were measured by the following methods.

(Weight reduction rate)
The weight loss rate (thermal decomposition resistance) of the obtained polymer particles was determined by thermogravimetric/differential thermal analysis (TG-DTA) under the following conditions.・Measuring device: STA7220 (manufactured by Hitachi High-Tech Science Co., Ltd.) ・Atmosphere: Nitrogen 200ml/min ・Heating temperature: 500°C ・Heating rate: 10°C/min ・Sample measurement container: Aluminum open cell

5 mg of the polymer particles obtained in the Examples and Comparative Examples were placed in an aluminum open cell and set in the measurement section. Thereafter, the measuring section was heated to 500° C. at a temperature increase rate of 10° C./min while nitrogen was injected at a rate of 200 ml/min.

The weight of the polymer particles when the temperature reached 350°C was measured, and the weight loss rate (wt%) was determined. The smaller the amount of decrease, the less likely thermal decomposition of the polymer particles will occur, indicating that the thermal decomposition resistance is excellent.

(YI value)
2 g of the obtained polymer particles were placed in a dryer set at 150° C. and heated at 150° C. for 1 hour in an air atmosphere.

Next, the YI value of the heated polymer particles was determined using a spectrophotometer CM-700d (manufactured by Konica Minolta, Inc.). Note that the YI value was calculated as the average value of three measurements.

The smaller the YI value, the better the resistance to heat yellowing.

Table 1 summarizes each component used in the polymerization of Examples and Comparative Examples and the evaluation results.

(Average particle size)
The average particle size of the obtained polymer particles is determined by measuring the particle size of 100 arbitrary particles from an image obtained using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation), and calculating the average value as the average particle size. did. The average particle diameter was observed using a microscope at an observation magnification of 15,000 times.

Claims (2)

A polymer particle containing a component derived from a monomer component containing styrene, methyl methacrylate, and a polyfunctional monomer having 2 to 6 ethylenically unsaturated groups in one molecule, wherein in 100 % by mass of the monomer component, the The content of styrene is in the range of 20 to 65% by mass, the content of the methyl methacrylate is in the range of 30 to 75% by mass, and the content of the polyfunctional monomer is in the range of 0.5 to 8% by mass. A polymer particle that satisfies the following conditions (i) and (ii).
(i) The YI value measured after heating the polymer particles at 150° C. for 1 hour in the atmosphere is 10 or less.
(ii) The polymer particles are heated at a rate of 10° C./min in a nitrogen atmosphere, and the weight loss rate when reaching 350° C. is 10% by weight or less. The polymer particles according to claim 1, wherein the polyfunctional monomer is ethylene glycol dimethacrylate.