JP2016138178A - Fine powder of (meth)acryl polymer and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine particle of a (meth)acryl polymer high in affinity with rubber and plastic, functioning as a reinforcement agent or a rheology control agent when blended to the above-mentioned compositions or dispersed in a resin monomer to cure the resin monomer, and excellent in handling ability of the resulting composition, and a manufacturing method therefor.SOLUTION: There is provided a fine particle of a (meth)acryl polymer capable of being obtained by polymerizing a monomer component containing a (meth)acryl-based polyfunctional monomer of 50 mass% or more and of which a primary particle having average particle diameter of 0.5 μm or less aggregates to form a secondary particle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fine powder of (meth) acrylic polymer and a method for producing the same.

  Conventionally, inorganic silica powder has been widely used as a filler for rubber and plastic, but the surface of inorganic silica powder that is widely used has a hydrophilic surface to increase the affinity for rubber and plastic. It was necessary to perform a special surface treatment.

  On the other hand, when a fine powder of a (meth) acrylic polymer polymerized in a non-aqueous solvent is used as a filler, there is an advantage that the affinity for rubber or plastic is higher than that of the silica powder.

  As fine powders of (meth) acrylic polymer obtained by polymerization in a non-aqueous solvent, for example, fine powders disclosed in Patent Documents 1 to 3 are known.

  Patent Document 1 discloses a polymer fine particle having a uniform particle size while a crosslinkable monomer such as diethylene glycol dimethacrylate is polymerized in an organic solvent to leave a secondary reactive functional group that can be modified on the surface. A manufacturing method is disclosed.

  Patent Document 2 discloses microporous oil-absorbing polymer fine particles obtained by polymerizing a polyunsaturated monomer in a silicon-based solvent. Patent Document 2 also discloses the form of aggregates and agglomerates formed from the fine particles.

  In Patent Document 3, a raw material monomer is dissolved in a raw material monomer including a monomer having two or more unsaturated double bonds and an unsaturated monomer having a hydrophilic functional group or an active hydrogen group. A method for producing crosslinked spherical polymer fine particles obtained by polymerizing in a medium in which the produced polymer is not dissolved is disclosed.

JP 2007-197565 A Japanese Patent Laid-Open No. 10-244153 JP 2006-282774 A

  The problem of the present invention is that it has a high affinity with rubber and plastic, and functions as a reinforcing agent and a rheology control agent when blended in the above components or when dispersed in a resin monomer to cure the resin monomer, and Another object of the present invention is to provide a (meth) acrylic polymer fine powder and a method for producing the same, in which the resulting composition has excellent handling properties.

  As a result of intensive studies to solve the above problems, the present inventors use a specific (meth) acrylic polymer fine powder obtained by polymerizing a monomer component containing a specific amount of a (meth) acrylic polyfunctional monomer. Thus, it has been found that the above problems can be solved.

  The present invention includes, for example, the following [1] to [7].

  [1] A fine powder of a (meth) acrylic polymer obtained by polymerizing a monomer component containing 50% by mass or more of a (meth) acrylic polyfunctional monomer, and the fine powder has an average particle size of 0.5 μm or less. A fine powder of (meth) acrylic polymer in which primary particles are aggregated to form secondary particles.

  [2] The (meth) acrylic polymer is obtained by polymerizing a monomer component containing 98% by mass or more of a (meth) acrylic polyfunctional monomer in 100% by mass of the monomer component ( Fine powder of (meth) acrylic polymer.

  [3] The (meth) acrylic polymer contains 50% by mass or more of a (meth) acrylic polyfunctional monomer having 3 or more (meth) acryloyl groups in 100% by mass of the monomer component, and (meth) A monomer component containing a total of 98% by mass or more of a (meth) acrylic bifunctional monomer having two acryloyl groups and a (meth) acrylic polyfunctional monomer having three or more (meth) acryloyl groups, or (meth) The fine powder of the (meth) acrylic polymer according to [2], obtained by polymerizing a monomer component containing 98% by mass or more of a (meth) acrylic polyfunctional monomer having 3 or more acryloyl groups.

[4] The height (A) of the maximum absorption peak derived from a carbonyl group, measured in the range of 1797 to 1662 cm ⁻¹ in FT-IR of the (meth) acrylic polymer, and from 1662 to 1587 cm ⁻¹ . The absorption peak height ratio (B) / (A) × 100 with respect to the height (B) of the maximum absorption peak derived from the vinyl group measured in the range is 1.5 or more, [1] to [3 ] The fine powder of the (meth) acrylic polymer in any one of.

  [5] The (meth) acrylic polymer is obtained by polymerizing the monomer component in a polymerization solvent in which the monomer component is dissolved but the (meth) acrylic polymer is not dissolved. [4] The fine powder of the (meth) acrylic polymer according to any one of [4].

  [6] A method for producing a fine powder of the (meth) acrylic polymer according to any one of [1] to [5], comprising a monomer component containing 50% by mass or more of a (meth) acrylic polyfunctional monomer. A method for producing a fine powder of a (meth) acrylic polymer, comprising a step of polymerizing in a polymerization solvent in which the monomer component is dissolved but the produced (meth) acrylic polymer is not dissolved.

  [7] The method for producing a fine powder of the (meth) acrylic polymer according to [6], wherein the monomer component is polymerized while being irradiated with ultrasonic waves.

  According to the present invention, it is possible to provide a fine powder of a (meth) acrylic polymer, which has high affinity with rubber and plastic, and excellent handleability of a composition obtained by blending with the above components, and a method for producing the same. it can. The fine powder of the (meth) acrylic polymer also functions as a reinforcing agent or a rheology control agent when kneaded into rubber or plastic or dispersed in a resin monomer to cure the resin monomer.

FIG. 1 is a scanning electron microscope image of the fine powder of (meth) acrylic polymer obtained in Example 1. FIG. 2 is a scanning electron microscope image of the fine powder of (meth) acrylic polymer obtained in Example 2. FIG. 3 is a scanning electron microscope image of the fine powder of (meth) acrylic polymer obtained in Comparative Example 1.

  Hereinafter, the fine powder of the (meth) acrylic polymer of the present invention and the production method thereof will be described.

  Herein, “(meth) acryloyl” is used to indicate acryloyl and / or methacryloyl, “(meth) acrylate” is used to indicate acrylate and / or methacrylate, and “ “(Meth) acryl” is used to indicate both or one of acrylic and methacrylic.

[Fine powder of (meth) acrylic polymer]
The fine powder of the (meth) acrylic polymer of the present invention includes secondary particles formed by agglomerating primary particles of a (meth) acrylic polymer having an average particle size of 0.5 μm or less. Hereinafter, the fine powder of the (meth) acrylic polymer is also referred to as “fine powder”.

  Since the fine powder of the (meth) acrylic polymer of the present invention has high lipophilicity, it has a high affinity for rubber and plastic. Therefore, it is not necessary to perform a special surface treatment when blending the fine powder with the above components. This fine powder exhibits a high function as a reinforcing agent and a rheology control agent when kneaded into rubber and plastic or dispersed in a resin monomer to cure the resin monomer.

  The (meth) acrylic polymer is obtained by polymerizing a monomer component containing 50% by mass or more of a (meth) acrylic polyfunctional monomer described below. As said monomer component, you may use at least 1 type chosen from a functional group containing monomer and another monomer with a (meth) acrylic polyfunctional monomer.

[(Meth) acrylic polyfunctional monomer]
A (meth) acrylic polyfunctional monomer is a compound having two or more (meth) acryloyl groups, a (meth) acrylic bifunctional monomer having two (meth) acryloyl groups, and 3 (meth) acryloyl groups. Examples include (meth) acrylic trifunctional monomers having four (meth) acrylic tetrafunctional monomers having four (meth) acryloyl groups.

  The number of (meth) acryloyl groups in the (meth) acrylic polyfunctional monomer is usually 2 or more, preferably 3 or more and 6 or less.

Examples of (meth) acrylic bifunctional monomers include:
(Poly) alkylene glycol di (meth) acrylates such as (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, (poly) tetramethylene glycol di (meth) acrylate;
1,6-hexanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1, 12-dodecanediol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 2,4-diethyl-1,5-pentanediol di (meth) acrylate, butylethylpropanediol di ( Alkanediol di ((meth) acrylate, 3-methyl-1,7-octanediol di (meth) acrylate, 2-methyl-1,8-octanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. (Meth) acrylate;
Ethoxylated cyclohexanedimethanol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, 1,1,1- Trishydroxymethylethanedi (meth) acrylate;
Is mentioned.

  Examples of the (meth) acrylic polyfunctional monomer having three or more (meth) acryloyl groups include trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, and trimethylolpropane propoxytri (meth). Examples include acrylate, glycerin propoxy tri (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

  The (meth) acrylic polyfunctional monomer may be used alone or in combination of two or more.

  The (meth) acrylic polymer is a monomer component containing 50% by mass or more, preferably 80% by mass or more, more preferably 98% by mass or more of the (meth) acrylic polyfunctional monomer in 100% by mass of the monomer component. Is obtained. By polymerizing the monomer component containing the (meth) acrylic polyfunctional monomer within the above range, carbon-carbon double bonds can be present in the fine powder of the (meth) acrylic polymer at a predetermined ratio. . The fine powder of (meth) acrylic polymer has a higher function as a reinforcing agent or a rheology control agent as the amount of carbon-carbon double bonds is larger.

  In 100% by mass of the monomer component, it is preferable to contain 50% by mass or more, more preferably 80% by mass or more, and more preferably 98% by mass or more of a (meth) acrylic polyfunctional monomer having 3 or more (meth) acryloyl groups. It is further preferable to include it. When a (meth) acrylic polyfunctional monomer having three or more (meth) acryloyl groups is used, the fine powder of the (meth) acrylic polymer produced is dispersed when kneaded into rubber or plastic or in the resin monomer. When the resin monomer is cured, the elongation to break can be lengthened, and the reinforcing material exhibits a high function.

[Functional group-containing monomer]
The fine powder of the (meth) acrylic polymer of the present invention has a high affinity for rubber and plastics without being subjected to a special surface treatment. However, in order to control the surface state of the fine powder, a fluorine substituent, a hydroxy group The monomer component may contain a functional group-containing monomer having a functional group such as a glycidyl group.

  Examples of the functional group-containing monomer include a fluorine substituent-containing monomer, a hydroxy group-containing monomer, and a glycidyl group-containing monomer.

  As a fluorine substitution containing monomer, fluorine substitution (meth) acrylate is mentioned, for example.

  Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and chloro-2-hydroxyethyl (meth) acrylate.

  Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate.

  The said functional containing monomer may be used individually by 1 type, and may use 2 or more types.

  When the functional-containing monomer is used, the functional group-containing monomer is preferably included in an amount of 0.01 to 50% by mass, more preferably 0.01 to 10% by mass in 100% by mass of the monomer component. It is particularly preferable to contain 01 to 2% by mass.

[Other monomers]
Other monomers include, for example, (meth) acrylic monofunctional monomers, aromatic monovinyl monomers, aromatic divinyl monomers, addition polymerizable unsaturated aliphatic monocarboxylic acids, addition polymerizable unsaturated aliphatic dicarboxylic acids, Examples include vinyl ester monomers, vinyl ether monomers, monoolefin monomers, halogenated olefin monomers, and diolefin monomers.

  Examples of the (meth) acrylic monofunctional monomer include (meth) acrylic acid, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, N-methyl (meth) acrylamide, and N-ethyl. (Meth) acrylamide, N-propyl (meth) acrylamide, N-hexyl (meth) acrylamide, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, diethylene glycol mono (meth) acrylate, methoxyethyl (meth) acrylate, dicyclopenta Le (meth) acrylate, dicyclopentenyl (meth) acrylate and isobornyl (meth) acrylate.

  Examples of the aromatic monovinyl monomer include styrene, α-methylstyrene, vinyl toluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, and sodium styrenesulfonate.

  Examples of the aromatic divinyl monomer include divinylbenzene, divinylbiphenyl, divinylnaphthalene, and diallyl phthalate.

  Examples of the addition polymerizable unsaturated aliphatic monocarboxylic acid include crotonic acid, α-methylcrotonic acid, α-ethylcrotonic acid, isocrotonic acid, tiglic acid, and ungelic acid.

  Examples of the addition polymerizable unsaturated aliphatic dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, and hydromuconic acid.

  Examples of vinyl ester monomers include vinyl formate, vinyl acetate, and vinyl propionate.

  Examples of vinyl ether monomers include vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, and vinyl cyclohexyl ether.

  Examples of the monoolefin monomer include ethylene, propylene, butene-1, pentene-1, and 4-methylpentene-1.

  Examples of the halogenated olefin monomer include vinyl chloride and vinylidene chloride.

  Examples of the diolefin monomer include butadiene, isoprene, and chloroprene.

  Other monomers may be used alone or in combination of two or more.

[Configuration of fine powder of (meth) acrylic polymer]
In the fine powder of the (meth) acrylic polymer of the present invention, primary particles of the (meth) acrylic polymer having an average particle size of 0.5 μm or less aggregate to form secondary particles. The average particle diameter can be measured by observation with an electron microscope. The average particle size of the primary particles is 0.5 μm or less, preferably 0.01 μm or more and less than 0.1 μm. Moreover, the average particle diameter of secondary particle | grains is 1-10000 micrometers normally from points, such as a use and productivity, Preferably it is 1-1000 micrometers. The fine powder of (meth) acrylic polymer containing secondary particles as described above is excellent in handling properties.

In the fine powder of the (meth) acrylic polymer of the present invention, the absorption peak height ratio (B) / (A) × 100 is preferably 1.5 or more, more preferably 2.0 or more and 13 or less. preferable. Here, when FT-IR (Fourier transform infrared absorption spectrum) is measured for the fine powder, (A) is a maximum absorption peak derived from a carbonyl group measured in a range of 1797 to 1662 cm ⁻¹ . (B) is the height of the maximum absorption peak derived from the vinyl group, measured in the range of 1662 to 1587 cm ⁻¹ . A larger value of the absorption peak height ratio (B) / (A) × 100 indicates that the fine powder contains more double bonds.

  The amount of double bonds in the fine powder can be adjusted according to the type of monomer component used. When the amount of carbon-carbon double bonds is large, the fine powder can be used as a reinforcing agent and a rheology control agent when kneaded into rubber or plastic or dispersed in a resin monomer to cure the resin monomer. High performance.

[Method for producing fine powder of (meth) acrylic polymer]
A known method can be adopted as a method for producing a (meth) acrylic polymer for forming a fine powder of a (meth) acrylic polymer, and examples thereof include precipitation polymerization. Here, precipitation polymerization refers to polymerization performed in a solvent in which a monomer component is dissolved and a produced polymer is not dissolved. Precipitation polymerization is preferable in terms of control of the particle diameter of the polymer particles and dispersibility.

  The polymerization solvent is not particularly limited, and can be appropriately selected from common solvents according to the raw materials used. It is preferable to use a polymerization solvent that dissolves the monomer component and does not dissolve the (meth) acrylic polymer produced. It is particularly preferable to use an organic solvent in that a polymer having high lipophilicity and excellent affinity to rubber and plastic can be obtained.

  Examples of the polymerization solvent include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethylbutanol, 1-heptanol, 2- Alcohols such as heptanol, 3-heptanol, 2-octanol, 2-ethyl-1-hexanol, benzyl alcohol, cyclohexanol; methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, diethylene glycol monob Ether alcohols such as ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl propionate, (alkyl) cellosolve acetate, ethyl carbitol acetate, butyl carbitol acetate Pentane, 2-methylbutane, n-hexane, cyclohexane, 2-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, heptane, n-octane, isooctane, 2,2,3-trimethylpentane, decane , Nonane, cyclopentane, methylcyclopentane, methylcyclohexane, ethylcyclohexane, p-menthane, dicyclohexyl, benzene, toluene, xylene, ethylbenzene, etc. aliphatic or aromatic Halogenated hydrocarbons such as carbon tetrachloride, trichloroethylene, chlorobenzene, and tetrabromoethane; Ethers such as ethyl ether, dimethyl ether, trioxane, and tetrahydrofuran; Acetals such as methylal and diethyl acetal; Formic acid, acetic acid, propion Fatty acids such as acids; sulfur and nitrogen-containing organic compounds such as nitropropene, nitrobenzene, dimethylamine, monoethanolamine, pyridine, dimethylformamide, dimethyl sulfoxide, acetonitrile, and N-methyl-2-pyrrolidone. These may be used alone or in combination of two or more.

  The polymerization solvent is not particularly limited, but from the viewpoint of dissolving monomer components such as a (meth) acrylic polyfunctional monomer and a (meth) acrylic monofunctional monomer, and precipitating the produced (meth) acrylic polymer, the solubility parameter ( It is preferable to use a polymerization solvent having an SP value of about 7 to 15. Moreover, it is preferable to use the polymerization solvent whose boiling point is 60-105 degreeC under a normal pressure from a viewpoint of the solvent removal at the time of collect | recovering the secondary particles which precipitated.

  The usage-amount of a polymerization solvent is 200-2000 mass parts normally with respect to 100 mass parts of monomer components, Preferably it is 500-2000 mass parts, More preferably, it is 800-2000 mass parts. When the amount of the polymerization solvent is in the above range, it is preferable because the form of the secondary particles during the polymerization reaction can be easily controlled.

  When producing the (meth) acrylic polymer, it is preferable to use a polymerization initiator in order to initiate polymerization of the monomer component. The polymerization initiator is preferably a polymerization initiator that is soluble in the polymerization solvent used in the polymerization, and examples of the polymerization initiator that can be suitably used include peroxides and azo compounds. .

  Examples of peroxides include potassium persulfate, ammonium persulfate, benzoyl peroxide, lauroyl peroxide, and dialkyl peresters. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropylpropionitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), dimethyl-2 , 2′-azobis (2-methylpropionate) and the like.

  A polymerization initiator may be used individually by 1 type, and may use 2 or more types.

  It is preferable that the usage-amount of a polymerization initiator is 0.01-10 mass parts with respect to a total of 100 mass parts of a monomer component. When the amount of the polymerization initiator is within the above range, a fine powder of (meth) acrylic polymer in which many unsaturated double bonds remain can be produced.

  When the (meth) acrylic polymer is produced, other components can be used as necessary. Other components are not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include a dispersion stabilizer and a surfactant.

  In order to improve the lipophilicity and obtain a fine powder excellent in affinity to rubber and plastic, the amount of the dispersion stabilizer and the surfactant used is 1 mass for each 100 mass parts of the monomer component. It is preferably no greater than 0.1 parts, more preferably no greater than 0.1 parts by mass, and particularly preferably 0 parts by mass.

  Any dispersion stabilizer and surfactant can be used without particular limitation as long as they are soluble in the organic solvent to be used.

  The polymerization temperature is appropriately selected according to the type of monomer. The polymerization temperature is usually 50 to 90 ° C, more preferably 60 to 80 ° C. Moreover, superposition | polymerization time is 0.1 to 5 hours normally, More preferably, it is 0.5 to 1 hour.

  Polymerization may be performed while stirring by a known mechanical means.

  Ultrasonic irradiation may be performed during the polymerization. By performing ultrasonic irradiation, it is possible to adjust the aggregation of primary particles to obtain secondary particles having an appropriate size, and to further suppress the aggregation of secondary particles. Although it does not restrict | limit especially as an intensity | strength of an ultrasonic wave, 100-1000 W / L is preferable.

  The fine powder of (meth) acrylic polymer is manufactured through a solvent removal process such as suction filtration, centrifugal separation, and cross-flow cleaning equipment, a drying process such as shelf drying, vacuum drying, and spray drying, and a pulverizing process. It is preferable. Moreover, the obtained fine powder may be classified as necessary in order to make the particle diameter uniform.

[Use]
The fine powder of the (meth) acrylic polymer of the present invention can be suitably used as a general filler or additive, and when kneaded into rubber or plastic, the carbon-carbon double bond in the particles It functions as a reinforcing agent and rheology control agent. In particular, when the resin matrix is made of a (meth) acrylic copolymer, a cross-linked structure can be formed by a carbon-carbon double bond between the resin matrix and the fine powder of the present invention, so the strength is greatly improved. Can be made.

  When the fine powder is used as a filler, it can be used by dispersing it in a resin monomer such as an acrylic monomer and curing the resin monomer containing the fine powder, or by kneading it into rubber or plastic. You can also.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

[Average particle size]
The average particle diameter of the fine powder of the (meth) acrylic polymer was measured using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation). For the primary particles, 10 arbitrary particle sizes were measured, and the average value was taken as the average particle size.

[FT-IR measurement]
Using FT-IR (HORIBA Ltd.) (meth) measuring the fine powder of the acrylic polymer, the maximum absorption peak height derived from the carbonyl group of 1797~1662cm ^-1 (A) and 1662～1587Cm ^-1 The maximum absorption peak height (B) derived from the vinyl group was measured, and the absorption peak height ratio (B) / (A) × 100 was calculated.

[Example 1]
In a reactor equipped with a stirrer, a nitrogen gas inlet tube, a thermometer and a reflux condenser, 100 parts by mass of trimethylolpropane triacrylate, 900 parts by mass of ethyl acetate (manufactured by Aldrich) as a polymerization solvent, and a polymerization initiator 1 part by mass of 2,2′-azobisisobutyronitrile (manufactured by Aldrich) was charged to obtain a reaction solution.

  While introducing nitrogen gas and applying ultrasonic waves to the reaction solution, the temperature of the reaction solution was raised to 70 ° C. to proceed the polymerization reaction. As soon as the temperature of the reaction solution reached 70 ° C., polymer deposition was confirmed.

  After maintaining the reaction solution at 70 ° C. for 1 hour, the reactor was cooled to room temperature to stop the polymerization reaction. Thereafter, the reaction solution was filtered to separate precipitates and then dried to obtain a fine powder of a (meth) acrylic polymer.

  The average particle size of primary particles of the obtained fine powder was 0.04 μm, and the average particle size of secondary particles was 1 μm or more. Moreover, the absorption peak height ratio (B) / (A) × 100 measured by FT-IR was 2.5. A scanning electron microscope image of the fine powder of the (meth) acrylic polymer obtained in Example 1 is shown in FIG.

[Example 2]
A fine powder of (meth) acrylic polymer was obtained in the same manner as in Example 1 except that 100 parts by mass of trimethylolpropane triacrylate was changed to 100 parts by mass of ethylene glycol dimethacrylate.

  The average particle size of primary particles of the obtained fine powder was 0.04 μm, and the average particle size of secondary particles was 1 μm or more. The absorption peak height ratio (B) / (A) × 100 measured by FT-IR was 4.4. A scanning electron microscope image of the fine powder of (meth) acrylic polymer obtained in Example 2 is shown in FIG.

[Comparative Example 1]
(Meth) acrylic was prepared in the same manner as in Example 1 except that 100 parts by mass of trimethylolpropane triacrylate was changed to 60 parts by mass of methyl methacrylate and 40 parts by mass of trimethylolpropane triacrylate, and ethyl acetate was changed to isopropyl alcohol. A fine polymer powder was obtained.

  The average particle diameter of the primary particles of the obtained fine powder was 2.1 μm, and the average particle diameter of the secondary particles was 10 μm or more. Moreover, the absorption peak area ratio (B) / (A) × 100 measured by FT-IR was 1.0. A scanning electron microscope image of the fine powder of (meth) acrylic polymer obtained in Comparative Example 1 is shown in FIG.

〔Breaking strength〕
A monomer mixture composed of 90 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of acrylic acid was mixed with 0.5 part by mass of Irgacure 500 (manufactured by BASF) as a photopolymerization initiator, and prepared in the above examples or comparative examples. A fine powder of (meth) acrylic polymer was dispersed so as to be 5% by volume to obtain a dispersion. The obtained dispersion was applied in a sheet form on a polyethylene terephthalate (PET) separator and cured by irradiation with ultraviolet rays to obtain an acrylic rubber molded body. About the obtained molded object, the breaking strength was evaluated by the tensile test as follows.

  The obtained molded body was cut into a width of 20 mm and a length of 30 mm, a marked line was drawn at a position of 10 mm from both ends, and the both ends of the sample were fixed with vinyl tape to be reinforced, leaving a measurement length of 10 mm. Both ends of this sample were fixed to a chuck of a tensile tester and measured at a pulling speed of 200 mm / min to obtain a breaking strength (MPa). In addition, the elongation to break was measured.

  The results are shown in Table 1.

Claims (7)

It is a fine powder of a (meth) acrylic polymer obtained by polymerizing a monomer component containing 50% by mass or more of a (meth) acrylic polyfunctional monomer,
The fine powder is a fine powder of a (meth) acrylic polymer in which primary particles having an average particle size of 0.5 μm or less aggregate to form secondary particles.   The (meth) acrylic polymer according to claim 1, wherein the (meth) acrylic polymer is obtained by polymerizing a monomer component containing 98% by mass or more of a (meth) acrylic polyfunctional monomer in 100% by mass of the monomer component. Polymer fine powder. The (meth) acrylic polymer is 100% by mass of the monomer component,
A (meth) acrylic bifunctional monomer and a (meth) acryloyl group containing 50% by mass or more of a (meth) acrylic polyfunctional monomer having 3 or more (meth) acryloyl groups and 2 (meth) acryloyl groups (Meth) acrylic polyfunctional monomer having 3 or more and a monomer component containing 98% by mass or more in total, or
The fine powder of the (meth) acrylic polymer according to claim 2, obtained by polymerizing a monomer component containing 98% by mass or more of a (meth) acrylic polyfunctional monomer having three or more (meth) acryloyl groups. The height of the maximum absorption peak derived from the carbonyl group (A) measured in the range of 1797 to 1662 cm ⁻¹ in FT-IR of the (meth) acrylic polymer, and measured in the range of 1662 to 1587 cm ^−1. The absorption peak height ratio (B) / (A) × 100 with the height (B) of the maximum absorption peak derived from a vinyl group is 1.5 or more. A fine powder of the (meth) acrylic polymer according to item.   The said (meth) acryl polymer is obtained by superposing | polymerizing the said monomer component in the polymerization solvent in which the said monomer component melt | dissolves, but the said (meth) acryl polymer does not melt | dissolve. A fine powder of the (meth) acrylic polymer according to item 1.   It is a method of manufacturing the fine powder of the (meth) acrylic polymer of any one of Claims 1-5, Comprising: The monomer component containing 50 mass% or more of (meth) acrylic-type polyfunctional monomers is said monomer. A method for producing a fine powder of a (meth) acrylic polymer, comprising a step of polymerizing in a polymerization solvent in which components are dissolved but a produced (meth) acrylic polymer is not dissolved.   The method for producing a fine powder of the (meth) acrylic polymer according to claim 6, wherein the monomer component is polymerized while irradiating ultrasonic waves.