JP3940620B2 - Method for producing non-spherical polymer fine particles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to non-spherical polymer particles and production thereof. The polymer fine particles are effective in adding to paints and cosmetics to give them a viscous property, a light scattering property, a unique surface property, and a moist feeling to the skin.
[0002]
[Prior art]
Polymer fine particles having an average particle size of 2 to 300 μm are usually obtained by subjecting a liquid polymerizable vinyl monomer to droplet dispersion by forcibly dispersing a liquid polymerizable vinyl monomer in an aqueous medium using a homomixer or the like in the presence of a dispersion stabilizer. Manufactured. In the production of polymer fine particles by this suspension polymerization, the liquid polymerizable vinyl monomer is usually spherical due to its surface tension in an aqueous medium, and the polymer fine particles obtained by polymerization also become spherical fine particles with a smooth surface. . As a method for producing cage-like polymer particles, a hydrophilic vinyl monomer is used as a polymerizable vinyl monomer, and a crosslinkable monomer is subjected to suspension polymerization in the presence of an oil-soluble substance (Japanese Patent Laid-Open Nos. 61-87734 and 2). -255704) is known, but non-spherical polymer particles having irregular irregularities are not yet known.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide novel non-spherical polymer fine particles and a method for producing non-spherical polymer fine particles by suspension polymerization.
[0004]
[Means for Solving the Problems]
The present inventors have previously applied for a patent on a novel spherical polymer fine particle having a regular wrinkle-like structure on the fine particle surface and a method for producing the same (Japanese Patent Laid-Open No. 11-14139). When a liquid rubber is dissolved in a mixture of a polymerizable vinyl monomer and a crosslinkable monomer and subjected to suspension polymerization in an aqueous medium, the previous surface is different from a regular wrinkled structure, and the surface is rounded. Non-spherical polymer particles with regular irregularities can be obtained, and the non-spherical polymer particles have viscosity characteristics, light scattering characteristics, and surface characteristics that are different from those of regular wrinkle structures, and are mixed with cosmetics. As a result, it was found that the skin has a unique feel and the present invention was completed.
That is, the present invention
(1) 1 to 30 parts by weight of a liquid rubber is dissolved in a monomer mixture comprising 40 to 90 parts by weight of a hydrophobic polymerizable vinyl monomer and 1 to 40 parts by weight of a crosslinkable monomer. Except when the mixture of 40 to 90 parts by weight and the crosslinkable monomer 1 to 40 parts by weight contains 5 to 30 parts by weight of a styrenic elastomer and further contains 5 to 20 parts by weight of liquid rubber with respect to 100 parts by weight of the monomer mixture. )) Nonspherical block polymer having a particle size of 0.5 to 300 μm, an average particle size of 2 to 100 μm, an aspect ratio of 1.10 to 5.00, and a sphericity of 65 or less. Production method of fine particles,
(2) The non-spherical polymer fine particles according to (1), wherein the compressive strength at a deformation rate of 20% of the particles is in the range of 0.1 to 3.0 kgf / mm ² ;
(3) The method for producing non-spherical polymer fine particles according to (1) or (2), wherein the polymerizable vinyl monomer is a (meth) acrylic acid alkyl ester,
(4) The method for producing non-spherical polymer fine particles according to (1) or (2), wherein the crosslinkable monomer is alkylene glycol di (meth) acrylate,
It is.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The non-spherical mass in the non-spherical polymer fine particles in the present invention does not include a certain percentage or more of particles having a true spherical shape, but includes a certain percentage or more of massive fine particles having irregular irregularities with rounded surfaces. It means to be a thing. In other words, it is not thread-like, needle-like, rod-like, rod-like, extremely flat, etc., and has no sharp ridges or protrusions such as square protrusions or crushed grains, and a lump having a plurality of rounded irregularities on the surface, For example, it has a shape such as rice grain or potato, and a specific example thereof is as shown in FIG.
[0006]
The range of the average particle size is 2 to 100 μm, the particle size is desirably in the range of 0.5 to 300 μm, and more preferably, the range of the average particle size is 3 to 50 μm, and the particle size is 1 to 100 μm. More preferably, the average particle diameter is 3 to 30 μm and the particle diameter is 1 to 70 μm. If it is smaller than this range, it will be unpleasant, and it will be unpreferable, and if it is larger than this range, it will be unpleasant. The fine particles of the present invention preferably have an aspect ratio in the range of 1.10 to 5.00, more preferably 1.20 to 4.00. If it is lower than 1.10, the rolling effect is too great, and a moist feel cannot be obtained, and if it is higher than 5.00, it is often harsh and is not preferred.
[0007]
For the measurement of the aspect ratio, the ratio of the major axis (equivalent circle diameter) and the thickness of the particle is calculated by the following formula.
Aspect ratio = equivalent circle diameter (major axis) / thickness (minor axis)
The fine particles of the present invention preferably have a sphericity of 65 or less, more preferably 60 or less. If the sphericity is higher than this, the rolling effect is too great, and a moist feel cannot be obtained.
[0008]
To measure the sphericity, take an electron micrograph of solid particles with a scanning electron microscope, randomly select 100 particles that do not overlap each other, and the projected image of the particles is a perfect circle or projected image The number of particles having a shape in which the contour of the projected image is entirely included between the concentric circle having a semicircle of 90% of the radius of the circumscribed circle and the circumscribed circle To do. The compressive strength at a deformation rate of 20% of the particles is preferably in the range of 0.1 to 3.0 kgf / mm ² , more preferably 0.3 to 2.8 kgf / mm ² . If the compressive strength is lower than this, it is not preferable because it feels like a net, and if it is high, it is not preferable because a sufficiently moist feeling does not appear. The compressive strength is measured by measuring the compressive strength when the deformation rate of the particles at 25 ° C. is 20% with a micro compressive strength measuring machine such as MCTM-500 manufactured by Shimadzu Corporation.
[0009]
Examples of the hydrophobic polymerizable vinyl monomer used in the present invention include aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyl toluene, and alkyl acrylates such as methyl acrylate, ethyl acrylate, and butyl acrylate. Esters, alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, vinyl ester monomers such as vinyl acetate and vinyl propionate, vinylcyan monomers such as (meth) acrylonitrile, Hydrophobic vinyl monomers that do not have hydrophilic groups such as hydroxyl groups, carboxyl groups, amino groups, and sulfonic acid groups can be used in molecules such as vinyl halide monomers such as vinyl chloride and vinylidene chloride. .
[0010]
Examples of the crosslinkable monomer used in the present invention include aromatic divinyl compounds such as divinylbenzene and divinyltoluene, alkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and the like. Examples thereof include compounds having two or more polymerizable unsaturated bonds in one molecule such as tri (meth) acrylate such as methylolpropane tri (meth) acrylate and pentaerythritol tetra (meth) acrylate, and tetra (meth) acrylate.
[0011]
Examples of the liquid rubber used in the present invention include polyisoprene, polybutene, polybutadiene, and the like, and synthetic rubber that is liquid at room temperature, such as liquid chloroprene rubber, liquid nitrile rubber, liquid fluororubber, liquid silicone rubber, and liquid isoprene rubber. Is mentioned. These elastomers and rubbers can be used alone or in combination of two or more. The amount of each of the hydrophobic polymerizable vinyl monomer, the crosslinkable monomer, and the low crystalline elastomer or liquid rubber used is usually 40 to 90: 1 to 40: 1 to 30, preferably 45 to 80: 3 by weight. 30: 3-20. If the use amount of the hydrophobic polymerizable vinyl monomer, the crosslinkable monomer and the liquid rubber is out of the above range, polymer fine particles having non-spherical particles cannot be obtained.
[0012]
Moreover, in order to accelerate | stimulate the phase separation in the droplet which occurs during superposition | polymerization, the oil-soluble solvent which is compatible with a monomer mixture can be used as needed.
[0013]
Examples of the oil-soluble solvent include esters such as methyl acetate, ethyl acetate, butyl butyrate and isoamyl butyrate: ketones such as diethyl ketone and methyl ethyl ketone: and further aromatic hydrocarbons such as benzene, toluene and xylene: butane and pentane. And aliphatic hydrocarbons such as hexane: long-chain alkyl derivatives such as olive oil, lath oil, coconut oil, and castor oil. These oil-soluble solvents are used in an amount of about 5 to 20 parts by weight per 100 parts by weight of the monomer mixture. The dispersion solution obtained by dissolving the above-mentioned monomers and liquid rubber used in the present invention into droplets in an aqueous medium is subjected to suspension polymerization in the next step, which improves the dispersibility of the raw material droplets and the generated polymer particles. Therefore, an appropriate amount of a dispersion stabilizer such as various surfactants and polymer protective colloids is used.
[0014]
Examples of the dispersion stabilizer include surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, water-soluble polymers such as gelatin, methylcellulose, hydroxyethylcellulose, polyvinyl alcohol, and polyacrylate, tricalcium phosphate, magnesium carbonate, and the like. The slightly water-soluble inorganic substance is used. These dispersion stabilizers may be used alone or in combination of two or more. These dispersion stabilizers can be stably polymerized in the amount used in the usual suspension polymerization.
[0015]
In the suspension polymerization of the present invention, an appropriate amount of a chain transfer agent, a polymerization inhibitor or the like may be used as necessary in addition to the weight initiator. As the polymerization initiator, those usually used for this kind of reaction, for example, peroxide initiators such as benzoyl peroxide and lauroyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-iso Examples include azo polymerization initiators such as valeronitrile. These polymerization initiators are used by dissolving in a polymerizable monomer. Chain transfer agents may also be those commonly used for this type of reaction, such as monothiol, polythiol, xanthogen disulfide, thiuram disulfide, mercaptoacetic acid 2-ethylhexyl ester, octanoic acid 2-mercaptoethyl ester, mercaptoacetic acid methoxybutyl ester, mercapto. Propionic acid methoxybutyl ester, α-methylstyrene dimer, terpinolene and the like are preferably used. As the polymerization inhibitor, for example, an appropriate amount of a commonly used polymerization inhibitor such as sodium nitrite, sodium sulfite, cupric chloride and the like is used.
[0016]
The average particle size of the polymer fine particles is obtained by dispersing a mixed solution of hydrophobic polymerizable vinyl monomer, crosslinkable monomer, liquid rubber, etc., and having the same diameter as the dispersion-stabilized droplet size is obtained by the subsequent polymerization reaction. It is done. The size of the droplet diameter can be arbitrarily controlled by selecting the type and amount of the dispersion stabilizer and the rotational speed of a forced dispersing machine such as a homomixer. By adjusting a droplet having a target particle size and then polymerizing, a polymer fine particle of 2 to 300 μm can be optionally produced. The polymerization temperature in the polymerization reaction of the present invention varies depending on the type of polymerization initiator used, monomer, polymerization inhibitor added as necessary, chain transfer agent, etc., but is usually 30 to 100 ° C., preferably 50 to 90 ° C. After suspension polymerization, polymer fine particles are filtered off, washed with water and dried to obtain a dry powder composed of non-spherical polymer fine particles.
[0017]
【Example】
The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. In the examples, “parts” represents parts by weight.
Example 1
A mixture of 75 parts of methyl methacrylate and 5 parts of ethylene glycol dimethacrylate dissolved in 20 parts of polybutene (Nippon Petrochemical Co., Ltd., Nisseki Polybutene HV300) and 0.5 part of azobisisovaleronitrile 25 parts of a 10% aqueous solution of alcohol (Kuraray Co., Ltd., PVA205), 1 part of a 1% ethylene oxide-propylene oxide nonionic surfactant (Nippon Yushi Co., Ltd., Pronon 208) and 275 parts of ion-exchanged water were injected. did. The obtained mixed liquid was stirred at 7,000 rpm for 20 minutes using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a raw material dispersion. This raw material dispersion was charged into a polymerization reaction vessel equipped with a stirrer and a reflux condenser, heated to 80 ° C. with stirring under a nitrogen stream, and polymerized for 3 hours. The obtained polymer fine particle dispersion was dehydrated, washed, dried, and sieved to obtain an average particle size of 9 μm, a sphericity of 40, an aspect ratio of 1.20, and a compressive strength at 20% deformation of 1.65 kgf / mm. ² rice-like polymer fine particles [FIG. 1] 85 parts by weight were obtained. These particles are referred to as non-spherical polymer fine particles A.
[0018]
Comparative Example 1
The same operation was performed except that the amount of liquid rubber used in Example 1 was changed from 20 parts to 0 parts. The obtained particles become a spherical polymer having an average particle diameter of 11 μm, a sphericity of 92, an aspect ratio of 1.00, and a compressive strength at 20% deformation of 3.47 kgf / mm ² , thereby obtaining non-spherical polymer fine particles. I couldn't. [Figure 2]
[0019]
Comparative Example 2
The same operation as in Example 1 was performed except that 5 parts of ethylene glycol dimethacrylate was not added. An average particle diameter of 9 μm, a sphericity of 81, an aspect ratio of 1.02, and a compressive strength at 20% deformation of 3.21 kgf / mm ² spherical polymer fine particles (FIG. 3) 86 parts by weight were obtained. The particles had a smooth particle surface, and it was not possible to obtain nonspherical polymer particles. [Figure 3]
[0020]
Next, formulation examples using these non-spherical polymer fine particles are shown.
Formulation Example 1 Oily Compact Foundation Weight%
Carnavalo 4.0
Solid paraffin 4.0
Cetanol 4.0
Lanolin 7.0
Liquid paraffin 5.0
Behenyl alcohol 3.0
Activator 2.0
Pigment paste 25.0
Non-spherical polymer fine particle A 35.0
Sericite 10.0
Fragrance 1.0
An oily compact foundation was produced by the above formulation.
[0021]
【The invention's effect】
According to the present invention, non-spherical polymer fine particles can be obtained by dissolving a liquid rubber in a mixture of a hydrophobic polymerizable vinyl polymer and a crosslinkable monomer and subjecting it to suspension polymerization in an aqueous medium. The non-spherical polymer fine particles having a peculiar shape obtained in this way give a uniform composition that does not cause layer separation when blended with, for example, paints and cosmetics, and have the viscosity characteristics, light scattering characteristics and surface characteristics. It can be advantageously used to change and adjust. In particular, in cosmetics blended in cosmetics, a soft and silky feel that is not found in polymethyl methacrylate fine particles, polystyrene fine particles, etc. can be obtained.
[0022]
[Brief description of the drawings]
FIG. 1 is an enlarged photograph of fine particles obtained in Example 1. FIG.
2 is an enlarged photograph of the fine particles obtained in Comparative Example 1. FIG.
3 is an enlarged photograph of the fine particles obtained in Comparative Example 2. FIG.

Claims (4)

1 to 30 parts by weight of a liquid rubber is dissolved in a monomer mixture composed of 40 to 90 parts by weight of a hydrophobic polymerizable vinyl monomer and 1 to 40 parts by weight of a crosslinkable monomer. A mixture of 1 part by weight and 1 to 40 parts by weight of the crosslinkable monomer contains 5 to 30 parts by weight of a styrenic elastomer, and further includes a case where 5 to 20 parts by weight of liquid rubber is added to 100 parts by weight of the monomer mixture) Production of non-spherical polymer fine particles having a particle diameter of 0.5 to 300 μm, an average particle diameter of 2 to 100 μm, an aspect ratio of 1.10 to 5.00, and a sphericity of 65 or less. Law. The method for producing non-spherical polymer fine particles according to claim 1, wherein the compressive strength at a deformation rate of 20% of the particles is in the range of 0.1 to 3.0 kgf / mm ² . The method for producing non-spherical polymer fine particles according to claim 1 or 2, wherein the polymerizable vinyl monomer is an alkyl (meth) acrylate. The method for producing non-spherical polymer fine particles according to claim 1 or 2, wherein the crosslinkable monomer is alkylene glycol di (meth) acrylate.

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