JP2004196859A - Nonspherical resin particle containing inorganic compound and preparation process therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin particle with a high functionality or capable of being used for various purposes. <P>SOLUTION: The nonspherical resin particle containing an inorganic compound is characterized in that the inorganic compound is unevenly distributed on the surfaces of a lens-shaped particle having a plurality of curved surfaces or of an almost hemispherical particle having a plurality of curved surfaces and a flat surface. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to inorganic compound-containing non-spherical resin particles and a method for producing the same. More specifically, the present invention relates to inorganic compound-containing non-spherical resin particles in which an inorganic compound is unevenly distributed on a surface and has a lens shape or a substantially hemispherical shape, and a method for producing the same. The inorganic compound-containing non-spherical resin particles of the present invention include surface modifiers for silver salt films, film modifiers for magnetic tapes, thermal paper running stabilizers, toners, low shrinkage agents, dental materials, resin modifiers and the like. It is also suitable as a raw material for products in the fields of electronics, adhesives, medicine, cosmetics, papermaking, and general industry.
[0002]
[Prior art]
The purpose of improving the mechanical properties of plastics, the purpose of improving the cleaning properties without changing the chargeability of the developer, the purpose of improving the matte and concealing properties of paint, the purpose of improving the slipperiness of cosmetics, etc. Various resin particles are used for various purposes.
[0003]
Since the resin particles are produced by a pulverization method, an emulsion polymerization method, a suspension polymerization method, a seed polymerization method, a dispersion polymerization method, or the like, they usually have any of an amorphous shape and a spherical shape. However, development of resin particles having shapes other than those described above has been performed in order to realize further functionalization.
[0004]
For example, a pamphlet of International Publication No. WO01 / 70826 (Patent Document 1) discloses a non-spherical resin particle having a lens shape having a plurality of curved surfaces, or a substantially hemispherical shape formed by a plurality of curved surfaces and one plane. Is described. The shapes described in this pamphlet can be usefully used as the resin particles for the above purpose.
[0005]
Further, in order to realize functionalization from another viewpoint, an inorganic compound for imparting a desired function to resin particles is also included. As such a technique, for example, there is a technique described in JP-A-1-178558 (Patent Document 2) and JP-A-2-34602 (Patent Document 3). In these publications, an inorganic compound is uniformly dispersed in spherical resin particles.
[0006]
In addition, a technique for unevenly distributing an inorganic compound to resin particles has been proposed with the expectation that it will be used for further various purposes (Japanese Patent Application Laid-Open No. 10-88841; Patent Document 4). In this publication, a desired surface of a spherical resin particle is treated with a drug such as a protein to obtain a resin particle having a surface modified to have a different kind of anisotropy such as hydrophilicity and hydrophobicity.
[0007]
[Patent Document 1]
Pamphlet of International Publication Number WO01 / 70826
[Patent Document 2]
JP-A-1-178558
[Patent Document 3]
JP-A-2-34602
[Patent Document 4]
Japanese Patent Application Laid-Open No. 10-88841
[0008]
[Problems to be solved by the invention]
However, in any of the above techniques, it has not been possible to obtain resin particles in which the inorganic compound is unevenly distributed and which has an irregular or non-spherical shape. Therefore, to cope with high functionality and various purposes of use, it is desired to provide non-spherical resin particles in which the properties of particles are changed only on a specific surface by unevenly distributing an inorganic compound and a method for producing the same.
[0009]
[Means for Solving the Problems]
The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, the following inorganic compound-containing non-spherical resin particles and a method for producing the same have a lens-like or substantially hemispherical shape, and the inorganic compound has a surface It was found that non-spherical resin particles unevenly distributed were obtained, and the present invention was completed. That is, in the present invention, when an oil phase composed of a polymerizable vinyl monomer is subjected to suspension polymerization, the polymerization proceeds by previously mixing an inorganic compound and a hydrophobic organic compound having a specific viscosity with the polymerizable vinyl monomer. As a result, the fact that inorganic compounds and hydrophobic organic compounds move to the surface side of the particles is utilized.
[0010]
Thus, according to the present invention, an inorganic compound characterized in that the inorganic compound is unevenly distributed on the surface of a substantially hemispherical particle formed by a lens or a plurality of curved surfaces and one flat surface having a plurality of curved surfaces. Compound-containing non-spherical resin particles are provided.
[0011]
Furthermore, according to the present invention, 0.001 to 5 parts by weight of a phosphoric ester having a polymerizable functional group and / or alkoxysilane having a polymerizable functional group is mixed with 100 parts by weight of a polymerizable vinyl monomer in which an inorganic compound is dispersed. After mixing and dissolving 7 to 50 parts by weight of a hydrophobic liquid compound having a viscosity of 10 to 10,000,000 cSt at 25 ° C. in the mixture, the mixture is subjected to suspension polymerization in an aqueous system, and then the liquid compound is removed to remove the inorganic compound-containing compound. There is provided a method for producing non-spherical resin particles containing an inorganic compound, which is characterized by obtaining spherical resin particles.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The shape of the inorganic compound-containing non-spherical resin particles obtained by the present invention is not particularly limited as long as it is a lens shape having a plurality of curved surfaces or a substantially hemispherical shape formed by a plurality of curved surfaces and one plane. More specifically, examples include a hemispherical shape, a stone-like shape, a convex lens shape, a concave lens shape, and shapes similar thereto. Resin particles having such a shape have characteristics that are not found in ordinary disk-shaped particles, flat particles, and plate-shaped particles, such as optical characteristics such as light scattering and light condensing, and friction such as slipperiness. Has characteristics. Further, since it has a flat surface or a curved surface having a larger radius of curvature than a spherical shape, it also has properties that are not present in ordinary spherical particles, for example, adhesion or sticking properties.
[0013]
Furthermore, since the specific surface area is large, the surface reactivity and the carrying capacity of the functional substance are increased. In addition, because it is non-spherical, it not only has unique optical characteristics that could not be expected with conventional hollow or porous spherical particles, aggregates of spherical particles, but also improves chemical characteristics by surface modification of resin particles etc. It can also be expected to improve physical properties such as fluidity and fluidity.
[0014]
Further, the inorganic compound is unevenly distributed in the resin particles. Here, the uneven distribution does not mean a state in which the inorganic compound is uniformly distributed over the entire particle, but means a state in which the inorganic compound is included only near a specific surface layer of the particle. For example, in the case of lenticular particles, the compound is unevenly distributed on one of two curved surfaces intersecting with the minimum particle diameter line, and in the case of a substantially hemispherical particle, an inorganic compound is present on one of surfaces or planes intersecting with the minimum particle diameter line Is unevenly distributed.
Due to the uneven distribution of the inorganic compound, it is possible to obtain resin particles having a surface having directionality and anisotropy in order to cope with high functionality and various usage purposes.
The state in which the inorganic compound is unevenly distributed can be observed by a method such as a transmission microscope, a transmission electron microscope, and a scanning electron microscope.
[0015]
The resin particles of the present invention preferably have a range of 1.0 μm ≦ D ≦ 500 μm, where D is the maximum particle diameter of the particles as observed by a scanning electron microscope. More preferably, when 2 μm ≦ D ≦ 100 μm and the minimum particle diameter is d, the shape is 0.05 ≦ d / D ≦ 0.8. When d / D is less than 0.05, it is not preferable because the shape is close to a plate shape and the functional properties such as slipping property and concealing property are not improved. When the ratio is larger than 0.8, the shape becomes spherical or substantially spherical, and the improvement in the functionality cannot be expected as in the case where the ratio is less than 0.05. In addition, the maximum particle diameter and the minimum particle diameter in this specification mean the average of the values obtained by calculating the maximum particle diameter and the minimum particle diameter of each of 50 arbitrarily selected particles from a micrograph.
These shapes can be adjusted by selecting the type and the use ratio of the hydrophobic liquid compound and the polymerizable vinyl monomer described below.
[0016]
Hereinafter, the inorganic compound-containing non-spherical resin particles of the present invention will be described with reference to the production method.
First, an inorganic compound is dispersed in a polymerizable vinyl monomer.
The polymerizable vinyl monomer is uniformly mixed and dissolved with a hydrophobic liquid compound described below, and is reactive with the liquid compound during polymerization, for example, as long as it does not have polymerization reactivity or cross-linking reactivity. However, it may be monofunctional or polyfunctional.
[0017]
Examples of the monofunctional polymerizable vinyl monomer include, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert. -Butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, n-methoxystyrene, p-phenylstyrene, styrene such as p-chlorostyrene and 3,4-dichlorostyrene and derivatives thereof,
Ethylene unsaturated olefins such as ethylene, propylene, butylene and isobutylene; vinyl chlorides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Vinyl esters,
[0018]
Methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, acrylic acid Phenyl, α-methyl methyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate Α-methylene aliphatic monocarboxylic acids such as phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate Borate esters,
[0019]
Acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and the like. . Further, acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like can also be used.
[0020]
Also, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl compounds such as N-vinylpyrrolidone, vinyl naphthalene salts and the like can be used alone or in combination of two or more as long as the effects of the present invention are not impaired.
[0021]
Examples of the polyfunctional polymerizable vinyl monomer include a vinyl monomer having an allyl group such as allyl (meth) acrylate, and one molecule of a vinyl group such as divinyl adipate, divinylbenzene, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate. And a vinyl monomer having a plurality thereof. (Meth) acrylate means acrylate or methacrylate.
[0022]
The inorganic compound can be appropriately selected according to the function given to the resin particles. For example, an inorganic pigment or an inorganic magnetic material may be used. As the inorganic compound, for example, alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, various inorganic oxide pigments , Chromium oxide, cerium oxide, iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silica fine powder, silicon carbide, silicon nitride, boron carbide, tungsten carbide, titanium carbide, cerium oxide And the like. In particular, metal oxides such as zirconium oxide, titanium dioxide, and iron oxide can be suitably used.
[0023]
In addition, when titanium dioxide, zirconium oxide, zinc oxide, or the like is used as the inorganic compound, it is possible to impart ultraviolet shielding ability, and when magnetic iron oxide is used, magnetism is imparted. Can be.
The shape of these inorganic compounds is not particularly limited, and examples thereof include a spherical shape, an irregular shape, a scale shape, and a needle shape. Further, the particle size is preferably 1 μm or less, more preferably 0.5 μm or less, and still more preferably 0.3 μm or less. In particular, the particle diameter is preferably about 1/10 or less of the particle diameter of the finally obtained resin particles.
[0024]
The blending amount of the inorganic compound in the polymerizable vinyl monomer is not particularly limited, and depends on the type, specific gravity, and the like of the inorganic compound used. For example, based on 100 parts by weight of the polymerizable vinyl monomer, the amount of the inorganic compound is preferably 1 to 50 parts by weight, more preferably about 3 to 30 parts by weight. If the amount of the inorganic compound is less than 1 part by weight, the resulting resin particles do not have sufficient effects such as concealability due to the compounding of the inorganic compound, which is not preferable. On the other hand, if it exceeds 50 parts by weight, the effect of increasing the amount of addition is not so much seen, and the deformation of the resin particles may be inhibited, which is not preferable.
[0025]
In the present invention, such an inorganic compound needs to be dispersed in the polymerizable vinyl monomer in the presence of a phosphoric acid ester having a polymerizable functional group and / or an alkoxysilane having a polymerizable functional group. It is. As such, phosphates such as acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate, acid phosphoxypolyoxyethylene glycol monomethacrylate, γ-methacryloxypropyltrimethoxysilane, γ -Alkoxysilanes such as methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane and vinylethoxysilane can be suitably used. In particular, the above-mentioned phosphates are suitable because they have a high affinity for inorganic compounds and can effectively make the inorganic compounds hydrophobic.
[0026]
In the absence of a phosphoric acid ester having a polymerizable functional group and / or an alkoxysilane having a polymerizable functional group, a silane having no reactivity with the resin particles of the present invention which is generally used as a surface treatment agent for an inorganic compound When an inorganic compound is subjected to a hydrophobizing treatment using a coupling agent such as a coupling agent or a titanate coupling agent, the inorganic compound is not immobilized on the surface of the resin particles, and the production of the resin particles of the present invention. In the step, the inorganic compound is detached from the surface of the resin particles in the process of removing the liquid compound. Therefore, in the present invention, the use of a phosphoric acid ester having a polymerizable functional group and / or an alkoxysilane having a polymerizable functional group is used for the purpose of immobilizing the inorganic compound on the surface of the resin particles.
[0027]
In the present invention,
(1) A phosphoric acid ester having a polymerizable functional group and / or an alkoxysilane having a polymerizable functional group is previously dissolved or dispersed in a polymerizable vinyl monomer, and then an inorganic compound is added, or
(2) adding phosphates having a polymerizable functional group and / or alkoxysilanes having a polymerizable functional group simultaneously with the inorganic compound,
Thereafter, it is preferable to perform a dispersion treatment of the inorganic compound using a suitable stirring device or the like.
[0028]
The addition amount of the phosphoric acid ester having a polymerizable functional group and / or the alkoxysilane having a polymerizable functional group also depends on the type and amount of the inorganic compound used and the type of the phosphoric ester used. . For example, the amount is preferably 0.001 to 20 parts by weight, more preferably about 2 to 10 parts by weight, based on 100 parts by weight of the composition containing the polymerizable vinyl monomer. That is, if the amount is less than 0.001 part by weight, the effect of improving the dispersion stability of the inorganic compound by addition thereof and the effect of preventing the inorganic compound from migrating into the aqueous phase during suspension and during the polymerization process cannot be sufficiently expected. On the other hand, if it exceeds 20 parts by weight, the effect is not so much improved even if the added amount is increased, so that it is not preferable.
[0029]
The apparatus for dispersing the inorganic compound in the polymerizable vinyl monomer in the presence of the phosphoric acid ester and / or the alkoxysilane is not particularly limited, but examples thereof include a ball mill, an attritor, and a sand mill. Preferred examples include a shear type dispersion device such as a media type dispersion device, a homomixer, a homogenizer, and a biomixer, and an ultrasonic dispersion device.
[0030]
Next, 7 to 50 parts by weight of a hydrophobic liquid compound having a viscosity at 25 ° C of 10 to 1,000,000 cSt is mixed and dissolved in the obtained mixture.
The hydrophobic liquid compound used in the present invention has a viscosity at 25 ° C. of 10 to 10,000,000 cSt and has no copolymerizability with a polymerizable vinyl monomer, or a suspension with a functional group present in the vinyl monomer. It is preferable that the compound is a hydrophobic compound which does not undergo a cross-linking reaction during polymerization and which does not react with water as a medium or is not deteriorated by water.
[0031]
Specifically, organopolysiloxane or paraffin is preferable. Examples of the organopolysiloxane include polysiloxanes such as dimethylpolysiloxane, diphenylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and various organically modified polysiloxanes such as alkyl or fluorine alkyl modified. More preferred are dimethylpolysiloxane, diphenylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and fluorinated alkyl-modified methylpolysiloxane having a viscosity at 25 ° C. of 20 to 100000 cSt.
Examples of the paraffin include liquid paraffin, monocyclic cycloparaffin, bicyclic cycloparaffin, isoparaffin, and n-paraffin.
[0032]
Further, a polymerization initiator can be used as needed. As the polymerization initiator, oil-soluble peroxide-based or azo-based initiators usually used for suspension polymerization can be used. For example, for example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t -Peroxide initiator such as butyl hydroperoxide, diisopropylbenzene hydroperoxide,
[0033]
2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,3-dimethylbutyronitrile), 2,2'- Azobis (2-methylbutyronitrile), 2,2'-azobis (2,3,3-trimethylbutyronitrile), 2,2'-azobis (2-isopropylbutyronitrile), 1,1'-azobis (Cyclohexane-1-carbonitrile), 2,2'-azobis (4-methix-2,4-dimethylvaleronitrile), 2- (carbamoylazo) isobutyronitrile, 4,4'-azobis (4-cyanovalerin Acid), dimethyl-2,2'-azobisisobutyrate and the like.
[0034]
Among them, 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile) are preferable in that the desired resin particles are easily obtained. The polymerization initiator is preferably used in an amount of 0.01 to 10% by weight, particularly preferably 0.1 to 5.0% by weight, based on the polymerizable vinyl monomer.
[0035]
The monomer composition is subjected to suspension polymerization using an aqueous medium. In the suspension polymerization, usually 100 to 1000 parts by weight of an aqueous medium is used for 100 parts by weight of the monomer composition in order to stabilize the suspended particles. Examples of the aqueous medium include water and a mixed medium of water and a water-soluble medium such as alcohol.
[0036]
Further, a suspension stabilizer for stabilizing suspension polymerization of the monomer composition may be added to the aqueous medium. The suspension stabilizer is not particularly limited as long as the desired resin particles can be obtained. For example, phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate, and zinc phosphate, pyrophosphates such as calcium pyrophosphate, magnesium pyrophosphate, aluminum pyrophosphate, and zinc pyrophosphate, calcium carbonate, magnesium carbonate, and calcium hydroxide , Magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, colloidal silica and the like. Among them, it is preferable to use tribasic calcium phosphate, magnesium pyrophosphate or calcium pyrophosphate produced by a double decomposition method, or colloidal silica, because the target resin particles can be stably obtained.
[0037]
It is also possible to use a surfactant such as an anionic surfactant, a cationic surfactant, a zwitterionic surfactant or a nonionic surfactant in combination with the above suspension stabilizer.
Examples of the anionic surfactant include fatty acid oils such as sodium oleate and castor oil, alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, and alkyl naphthalene sulfonates. Alkane sulfonates, dialkyl sulfosuccinates, alkyl phosphates, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene alkyl sulfates, and the like.
[0038]
Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene- Oxypropylene block polymers and the like.
Examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride.
Examples of the amphoteric surfactant include lauryl dimethylamine oxide.
[0039]
These suspension stabilizers and surfactants may be used alone or in combination of two or more, but in consideration of the diameter of particles obtained from the monomer composition before polymerization and the dispersion stability during polymerization. It is preferable to use the dispersion stabilizer by appropriately selecting and using the dispersion stabilizer. Usually, the addition amount of the suspension stabilizer to the monomer is 0.5 to 15% by weight, and the addition amount of the surfactant is usually 0.001 to 0.2% by weight based on water.
[0040]
The monomer composition is added to the aqueous medium thus prepared, and suspension polymerization is performed. Examples of the addition method include a method in which a monomer composition is directly added to an aqueous medium and dispersed into monomer droplets by a stirring force of a propeller blade or the like, and a homomixer which is a disperser using a high shear force composed of a rotor and a stator. , Dispersion using an ultrasonic disperser or the like, high-pressure disperser or MPG (microporous glass) utilizing the collision force between droplets such as a microfluidizer and a nanomizer, and the collision force against the machine wall For example, there is a method in which the monomer composition is pressed into an aqueous medium through a porous membrane. Among these methods, the method using a high-pressure type disperser or MPG can make the particle diameters more uniform.
[0041]
The particle size can be adjusted by controlling the mixing conditions of the monomer composition and the aqueous medium, the amount of the dispersion stabilizer and the like, and the above-mentioned stirring conditions and dispersion conditions. The particle size is determined according to the intended use. According to this production method, particles having a diameter of 1.0 to 500 μm can be obtained, but preferably particles having a diameter of 2.0 to 100 μm are easily obtained.
[0042]
Next, polymerization is started by heating the aqueous medium in which the monomer composition is dispersed as spherical droplets. The stirring during the polymerization may be performed slowly enough to prevent the floating of the monomer droplets and the sedimentation of the resin particles after the polymerization. In the above suspension polymerization reaction, the polymerization temperature is preferably 30 to 100C, more preferably 40 to 80C. In general, the polymerization time while maintaining the temperature is preferably about 0.1 to 10 hours.
After completion of the polymerization, if necessary, the dispersion stabilizer is dissolved with hydrochloric acid or the like, and the resin particles are separated from the aqueous medium by operations such as suction filtration, centrifugation, and centrifugal filtration. Further, the obtained water-containing cake of the resin particles is washed with water and dried to obtain the target resin particles.
[0043]
Since the resin particles thus obtained are obtained as a mixture with a liquid compound, the liquid compound dissolves, but the resin is preferably removed by washing with a solvent that does not dissolve. Such solvents, depending on the type of liquid compound and the type of resin particles, are generally alcohols such as methanol, ethanol, isopropanol and isobutanol, pentane, hexane, heptane, octane, cyclohexane and the like. Washing is preferably performed using lower hydrocarbons, ethers such as ethyl ether and butyl ether, aromatics such as benzene, toluene and xylene, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone. The operation of removing the liquid compound may be repeated as necessary.
[0044]
The shape of the resin particles should be controlled in various ways depending on the type and viscosity of the monofunctional polymerizable vinyl monomer or polyfunctional polymerizable vinyl monomer, the liquid compound, the amount used, the polymerization rate, and the particle size of the resin particles. Is possible. Of these, the viscosity is greatly influenced by the viscosity of the liquid compound.
[0045]
For example, when a high-viscosity liquid compound is used for methacrylic acid ester, a hemispherical or thin convex lens-shaped resin particle composed of a spherical surface and a flat surface is easily obtained, and a low-viscosity liquid compound is used. , It is easy to obtain thick convex lens-shaped particles composed of a spherical surface and a curved surface.
According to the method of the present invention, it is possible to easily and inexpensively produce resin particles having a novel shape and an uneven distribution of inorganic compounds for a wide variety of resin types.
[0046]
The inorganic compound-containing non-spherical resin particles of the present invention include surface modifiers for silver salt films, film modifiers for magnetic tapes, thermal paper running stabilizers, toners, low shrinkage agents, dental materials, resin modifiers and the like. It is also suitable as a raw material for products in the fields of electronics, adhesives, medicine, cosmetics, papermaking, and general industry.
[0047]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[0048]
Example 1
In 200 g of water, a dispersion medium containing 5 g of magnesium pyrophosphate generated by a metathesis method as a dispersion stabilizer was added to a 500 ml separable flask, and 0.04 g of sodium lauryl sulfate and 0.02 g of sodium nitrite were dissolved as surfactants. An aqueous medium was used.
[0049]
Separately, 72 g of methyl methacrylate, 10 g of dimethylpolysiloxane (viscosity 1000 cSt, 25 ° C.) as a liquid compound, 18 g of titanium dioxide (trade name CR-50, manufactured by Ishihara Sangyo Co., average particle diameter 0.25 μm) as an inorganic compound, polymerization 0.5 g of acid phosphoxyethyl methacrylate (trade name: Light Ester P-1M, manufactured by Kyoeisha Co., Ltd.) was mixed as a phosphoric ester having a functional functional group, and the mixture was used using a homomixer (ULTRA TURRAX T-25 manufactured by IKA). At 8000 rpm for 10 minutes to obtain a monomer composition. Thereafter, 0.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was mixed and dissolved in the monomer composition.
[0050]
Further, the monomer composition was added to the aqueous medium. This mixture was finely dispersed at 8000 rpm for about 10 seconds using a homomixer (ULTRA TURRAX T-25 manufactured by IKA). The flask was equipped with a stirring blade, a thermometer, and a reflux condenser. After purging with nitrogen, the flask was placed in a 60 ° C water bath. Heating was continued at a stirring speed of 200 rpm for 10 hours to carry out a polymerization reaction.
[0051]
After confirming that the polymerization reaction was completed, the reaction solution was cooled, and hydrochloric acid was added until the pH of the slurry became about 2, to decompose the dispersant. The particles were suction-filtered with a Buchner funnel using filter paper and washed with 1.2 liters of ion-exchanged water to remove the suspension stabilizer. After drying the dehydrated cake after suction filtration, the resultant was dispersed in normal heptane, and suction filtration was repeated several times to obtain desired resin particles, and the shape was observed with an electron micrograph.
The obtained particles were hemispherical resin particles consisting of a flat surface and a spherical surface having a maximum particle size distribution of about 5 to 40 μm, and titanium dioxide was unevenly distributed on the flat surface. FIG. 1 shows a transmission micrograph of the resin particles, and FIG. 2 shows a schematic diagram thereof. Even if the obtained resin particles were dispersed in normal heptane and filtered by suction three times, titanium dioxide did not desorb from the resin particles.
[0052]
Further, the reflected light characteristics of the resin particles of Example 1 are evaluated as follows.
The reflected light characteristics of the fine particles (PMMA particles; trade name: Techpolymer MBT-0530A, average particle size: 5 μm, containing 30% titanium oxide) of the commercial product A containing the resin particles of Example 1 and a commercially available titanium oxide pigment inside the particles are as follows. Was measured as follows.
[0053]
First, a double-sided tape is attached to a black-and-white concealing test paper (manufactured by Toyo Seiki Co., Ltd.) so as not to block air. The resin particles are uniformly spread and applied to the adhesive side of the double-sided tape with a cosmetic puff. Use a brush to remove excess resin particles. As a sample, a three-dimensional photometer (Goniophotometer GP-200, manufactured by Murakami Color Research Laboratory Co., Ltd.), as shown in the schematic diagram of FIG. 3, a reflection angle of 0 ° to 90 ° at an incident angle of -45 °. Is measured. FIG. 4 shows luminous intensity at a reflection angle of 0 ° to 80 ° when the reflected light intensity is set to 100 at a reflection angle of 45 °.
[0054]
As is clear from the reflected light characteristic evaluation of FIG. 4, the resin particles of Example 1 have high reflected light intensity not only in the regular reflection direction but also in a wide angle with respect to the incident light. This indicates that, for example, when blended in a cosmetic such as a foundation, a soft focus effect that cannot be obtained with conventional resin particles in which a pigment is uniformly dispersed inside can be expected.
[0055]
Example 2
In Example 1, 64 g of methyl methacrylate, 20 g of dimethylpolysiloxane (viscosity 1000 cSt, 25 ° C.) as a liquid compound, 16 g of titanium dioxide (trade name: CR-50, manufactured by Ishihara Sangyo Co., Ltd.) as an inorganic compound, and alkoxysilane having a polymerizable functional group Resin particles were obtained in the same manner as in Example 1, except that 0.5 g of γ-methacryloxypropyltrimethoxysilane was used.
The obtained particles were hemispherical resin particles consisting of a flat surface and a spherical surface having a maximum particle size distribution of about 5 to 40 μm, and titanium dioxide was unevenly distributed on the flat surface. FIG. 5 shows a transmission micrograph of the resin particles, and FIG. 2 shows a schematic diagram thereof. Even if the obtained resin particles were dispersed in normal heptane and filtered by suction three times, titanium dioxide did not desorb from the resin particles.
[0056]
Example 3
Resin particles were obtained in the same manner as in Example 1 except that dimethylpolysiloxane having a viscosity of 100 cSt was used instead of dimethylpolysiloxane (viscosity: 1000 cSt, 25 ° C.) as the liquid compound.
The obtained particles were convex lens-shaped resin particles composed of a curved surface and a spherical surface having a maximum particle diameter of about 5 to 40 μm, and titanium dioxide was unevenly distributed on the curved surface. FIG. 6 shows a transmission micrograph of the resin particles, and FIG. 7 shows a schematic diagram thereof. Even if the obtained resin particles were dispersed in normal heptane and filtered by suction three times, titanium dioxide did not desorb from the resin particles.
[0057]
Example 4
Resin particles were obtained in the same manner as in Example 1, except that liquid paraffin having a viscosity of 100 cSt was used instead of dimethylpolysiloxane (viscosity 1000 cSt, 25 ° C.) as the liquid compound.
The obtained particles are convex lens-shaped resin particles having a curved surface and a spherical surface having a maximum particle diameter of about 5 to 40 μm, and titanium dioxide is unevenly distributed on the curved surface. was gotten. FIG. 8 shows a transmission micrograph of the resin particles, and FIG. 7 shows a schematic diagram thereof. Even if the obtained resin particles were dispersed in normal heptane and filtered by suction three times, titanium dioxide did not desorb from the resin particles.
[0058]
Example 5
Example 1 was repeated except that dimethylpolysiloxane (viscosity 1000 cSt, 25 ° C.) was used as the liquid compound, and a fluorinated alkyl-modified polysiloxane (fluorine-modified silicone oil, product name: Toray Dow Corning Silicone, product name FS1265) having a viscosity of 1000 cSt was used. Similarly, resin particles were obtained.
The obtained particles were hemispherical resin particles composed of a flat surface and a spherical surface having a maximum particle size distribution of about 5 to 40 μm, and titanium dioxide was unevenly distributed on the spherical surface. FIG. 9 shows a schematic diagram of the resin particles. Even if the obtained resin particles were dispersed in normal heptane and filtered by suction three times, titanium dioxide did not desorb from the resin particles.
[0059]
Example 6
Resin particles were obtained in the same manner as in Example 1 except that magnetic iron oxide (Talox synthetic iron oxide BL-100 manufactured by Titanium Industry Co., Ltd., average particle diameter: 0.4 μm) was used instead of titanium dioxide. .
The obtained particles were convex lens-shaped resin particles composed of a curved surface and a spherical surface having a maximum particle diameter of about 5 to 40 μm, and iron oxide was unevenly distributed on the curved surface as in Example 3. Even when the obtained resin particles were dispersed in normal heptane and filtered by suction three times, the magnetic iron oxide did not desorb from the resin particles.
[0060]
Comparative Example 1
Resin particles were prepared in the same manner as in Example 1, except that the phosphate esters were replaced with isopropyl triisostearoyl titanate (trade name: Plenact TTS manufactured by Ajinomoto Fine Techno Co.) which is a titanate coupling agent in Example 1. Obtained.
The obtained resin particles were convex lens-shaped resin particles having a flat surface and a spherical surface with a maximum particle diameter of 5 to 40 μm. However, when the obtained resin particles were dispersed in normal heptane and suction-filtered three times, titanium dioxide was detached from the resin particles.
[0061]
Comparative Example 2
Resin particles were obtained in the same manner as in Example 1 except that 1000 cSt of dimethylpolysiloxane was changed to normal heptane (0.2 cSt) as the liquid compound.
The obtained resin particles were spherical resin particles having a particle diameter of 8 to 50 μm, and the titanium dioxide was uniformly dispersed in the resin particles.
[0062]
Comparative Example 3
Example 1 was repeated except that 85 g of methyl methacrylate, 5 g of dimethylpolysiloxane (viscosity 1000 cSt, 25 ° C.) as a liquid compound, and 10 g of titanium dioxide (trade name: CR-50, manufactured by Ishihara Sangyo Co., Ltd.) as an inorganic pigment were used. Resin particles were obtained in the same manner as in Example 1.
The obtained resin particles were spherical resin particles having a particle diameter of 4 to 50 μm, and titanium dioxide was unevenly distributed in a part of the resin particles. FIG. 10 shows a schematic diagram of the obtained resin particles.
[0063]
【The invention's effect】
The inorganic compound-containing non-spherical resin particles of the present invention have a lens shape having a plurality of curved surfaces, or a substantially hemispherical shape formed by a plurality of curved surfaces and one plane, and the inorganic compound is formed on the curved surface or the plane. Are unevenly distributed, for example, light scattering property, hydrophilicity and hydrophobicity, or anisotropy such as positive charge and negative charge, magnetism, and the like, which are not present in conventional resin particles, can be imparted.
[0064]
Therefore, utilizing these properties, particles for diagnostic agents, medical materials, biocompatible materials, dental materials, cosmetic powders, antifouling paints, antifogging materials, antistatic agents, conductive adhesives There is a possibility of application to conductive sealing materials, magnetic particles, recording media, packing materials for chromatography and the like.
[Brief description of the drawings]
FIG. 1 is an electron micrograph of resin particles of Example 1.
FIG. 2 is a schematic view of resin particles of Examples 1 and 2.
FIG. 3 is a schematic diagram for explaining a method of measuring a reflected light intensity distribution.
FIG. 4 is a distribution diagram of reflected light intensity of the resin particles of Example 1.
FIG. 5 is a transmission micrograph of a resin particle of Example 2.
FIG. 6 is a transmission micrograph of a resin particle of Example 3.
FIG. 7 is a schematic diagram of resin particles of Examples 3 and 4.
FIG. 8 is a transmission micrograph of the resin particles of Example 4.
FIG. 9 is a schematic view of a resin particle of Example 5.
FIG. 10 is a schematic view of a resin particle of Comparative Example 3.

Claims (5)

Non-spherical resin particles containing an inorganic compound, wherein the inorganic compound is unevenly distributed on the surface of a substantially hemispherical particle formed by a lens having a plurality of curved surfaces or a plurality of curved surfaces and one plane. The inorganic compound-containing non-spherical resin particles have a shape of 1.0 μm ≦ D ≦ 500 μm and 0.05 ≦ d / D ≦ 0.8, where D is the maximum particle size and d is the minimum particle size. 2. The particles according to 1. In the case of lenticular particles, the inorganic compound is unevenly distributed on one of two curved surfaces intersecting the minimum particle diameter line, and in the case of substantially hemispherical particles, unevenly distributed on one of the curved surface or flat surface intersecting the minimum particle diameter line A particle according to claim 1. A mixture obtained by mixing 0.001 to 5 parts by weight of a phosphoric acid ester having a polymerizable functional group and / or an alkoxysilane having a polymerizable functional group with 100 parts by weight of a polymerizable vinyl monomer in which an inorganic compound is dispersed, has a viscosity at 25 ° C. The inorganic compound-containing non-spherical resin according to claim 1, wherein 7 to 50 parts by weight of a hydrophobic liquid compound having a viscosity of 10 to 1,000,000 cSt is mixed and dissolved, and then suspension polymerization is performed in an aqueous system, and then the liquid compound is removed. A method for producing non-spherical resin particles containing an inorganic compound, characterized by obtaining particles. The method according to claim 4, wherein the hydrophobic liquid compound is an organopolysiloxane or paraffin.

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