JPH0336041B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel spherical polymer having one or more spherical vacuoles inside, including transparency, moisture retention, air permeability, rolling properties, elasticity, dispersibility, etc. The purpose of this invention is to obtain a spherical polymer having spherical vacuoles with an average particle diameter of 0.5 to 50 μm and excellent properties. Conventionally, emulsion polymerization and/or suspension polymerization are known as general methods for obtaining spherical polymers. The emulsion polymerization method is a method in which an emulsion (monomer phase/aqueous phase type) in which a monomer phase is stably dispersed in an aqueous phase is formed using an emulsifier, and then a polymerization reaction is performed using a water-soluble polymerization initiator. ,
The suspension polymerization method involves creating a dispersion of monomer droplets while vigorously stirring the monomer phase and aqueous phase using a dispersion stabilizer such as polyvinyl alcohol or gelatin, and then using a polymerization initiator that is soluble in the monomer. This is a method of carrying out a polymerization reaction. In the case of emulsion polymerization, the size of the monomer droplets in the emulsion is 0.1 to 10 μm due to the use of an emulsifier.
However, since the polymerization reaction itself occurs in micelles, the average particle size of the spherical polymers produced is extremely fine, ranging from several tens to several thousand angstroms, and usually takes the form of a latex. In order to increase the average particle size of latex, rather than continuously dropping the monomer or adding it in parts,
Although it is effective to polymerize by charging the entire amount at once, in this case it is difficult to obtain a polymer with a narrow particle distribution, which is the greatest advantage of emulsion polymerization.
There is also a method of sequentially adding the remaining emulsionized monomers to a system in which some monomers are first charged and prepolymerized, but this not only complicates the process, but also It had the drawback of exhibiting a very wide particle size distribution with an average particle size of several tens of angstroms to about 3 microns. On the other hand, in the suspension polymerization method, the polymerization reaction occurs in monomer droplets in the dispersion, and the average particle size is 0.1 to 1.
Since spherical polymers with a diameter of mm are formed, it is much easier to remove the solids by performing excessive operations compared to the emulsion polymerization method described above, but it is desirable to obtain particles with even smaller particle sizes. However, it is not just a change or improvement of the dispersion stabilizer or an improvement in stirring efficiency.
It was extremely difficult to obtain spherical polymers with a size of less than 50μ. In other words, it is difficult to apply existing general polymerization methods to obtain spherical polymers with an average particle size of 0.5 to 50μ, and it is extremely difficult to produce them. There was no hope of making it hollow into a spherical shape. On the other hand, various attempts have been made to solve the above-mentioned drawbacks. For example, Japanese Patent Publication No. 51-23994 discloses a method for producing porous divinylbenzene resin, in which a spherical resin with a three-dimensional network structure is produced by emulsion polymerization or suspension polymerization in an aqueous medium. This is a method in which countless micropores are formed by the action of an organic solvent that is insoluble in the polymer, but the spherical polymer obtained by this method first has a large number of micropores of various sizes randomly existing inside the polymer. However, due to diffused reflection of light, it is impossible to obtain a highly transparent product. Furthermore, by not using organic solvents, it is possible to keep the pores in molecular size and improve transparency, but in this case, the resin becomes dense inside, and the apparent specific gravity is large (heavy). Moreover, it becomes highly rigid (hard). Further, as another method for producing a product similar to the one of the present invention, a method using a foaming aid or the like can be considered.
In this case, suspension polymerization or emulsion polymerization is used to obtain particles containing a volatile liquid, then the liquid is vaporized by heating, etc., and the expansion pressure is used to form hollow particles. However, a drawback in this case is that the resins that can be applied are limited. In other words, when using highly airtight materials such as acrylonitrile or vinylidene chloride, it is easy to obtain particles with a high degree of hollowness, but there is a risk that volatile liquid may remain inside. If the material is made of a material with low elasticity, gas leaks during expansion and the desired purpose cannot be achieved. Therefore, in reality, the only option is to create a copolymer by combining a material with high airtightness and one with low airtightness to adjust the pore size, or to carry out the process under strict temperature and pressure control. It cannot be said that it is a useful method when considering the industrial scale, such as particle size control. Furthermore, there are also problems with the structure of the particles. That is, this method has the disadvantage that it is difficult to apply to crosslinked particles. The main reason for using cross-linked particles is to improve physical properties and chemical resistance, but because of the cross-linked structure, they do not expand uniformly during expansion, making it difficult to obtain spherical particles in the end. In some cases, partial destruction may occur. On the other hand, even in the case of non-crosslinked particles,
The tension during expansion caused crystallization and opacity due to molecular rearrangement, and the final spherical particles had the disadvantage of becoming more rigid (harder). In recent years, it has become important to incorporate spherical particles with an average particle diameter of about 1 to 50 microns in cosmetics. The purpose of this is the expected effects of spherical particles, such as ease of spreading and lightness during application, as well as good dispersibility during production. Furthermore, porous spherical powders may also be used in some cases, and in this case, in addition to the effects derived from the spherical particles, they also have sebum and moisture control functions derived from the porosity. In addition, particles with an average particle size of 1 to 50μ are selected because if the particle size is smaller than 1μ, the cosmetic finish will become whiter and rolling properties will be poor, and if it exceeds 50μ, it will be difficult to roll. This is because the foreign body sensation (roughness) becomes stronger. However, the above-mentioned conventional particles and powders do not have sufficient effects on other important factors in cosmetics, such as soft feel during application and transparency as a makeup finish. The emergence of a new material that has both these properties has been awaited. However, it has been technically difficult to solve these problems using the conventional methods described above. Therefore, as a result of intensive research to solve these problems, the present inventor found that the average particle diameter is in the range of 0.5 to 50μ, which was difficult to achieve with existing technology, the apparent specific gravity is small, and the elasticity is low. Rich in sex,
We have discovered a method for producing highly transparent spherical polymers, and have now completed the present invention. The present invention provides 1 selected from hydrophobic monomers.
When polymerizing a species or two or more raw material monomers in an aqueous dispersion medium, a nonionic surfactant is added to the monomer phase (dispersoid phase) and an ionic surfactant is added to the aqueous phase (dispersion medium phase). Contain aqueous phase/
After forming a monomer phase/aqueous phase type multiple emulsion, radical polymerization is carried out using a polymerization initiator soluble in a hydrophobic monomer. The present invention relates to a method for producing a spherical polymer having an average particle diameter of 0.5 to 50μ. Examples of hydrophobic monomers applicable to the present invention include vinyl monomers such as vinyl chloride, acrylonitrile, methacrylonitrile, vinyl acetate, and methyl vinyl ether; acrylic acids such as acrylic acid and acrylic esters (methyl, ethyl); methacrylic acid monomers such as methacrylic acid and methacrylic acid esters (methyl, ethyl), styrene monomers such as styrene and α-methylstyrene, and vinylidene chloride, divinylbenzene, ethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate. However, the monomers are not limited to the above monomers as long as they are essentially hydrophobic and have translucency when polymerized, and these monomers can be used alone or in combination of two or more. Is possible. Examples of nonionic surfactants added to the monomer phase include polyoxyethylene oleyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan monooleate, and trioleate. Sorbitan, sorbitan monooleate, polyoxyethylene glycerin monostearate, polyoxyethylene hydrogenated castor oil, polyethylene glycol monooleate,
Examples include glycerin monooleate and glycerin tree fatty acid ester, and these can be used alone or in combination of two or more. Examples of ionic surfactants added to the aqueous phase as a dispersion medium include soaps such as sodium laurate, potassium stearate, sodium oleate, and potassium rosinate, sodium lauryl sulfate, sodium cetyl sulfate, and polyoxyethylene. Anion such as sodium lauryl ether sulfate, sodium dodecylbenzenesulfonate, sodium α-olefin sulfonate, sodium lauroylmethyltaurine, sodium lauroylsarcosine, sodium dioctyl sulfosuccinate, sodium lauroyl-L-glutamate, sodium polyoxyethylene lauryl ether phosphate, etc. Ionic surfactants, cationic surfactants such as lauryltrimethylammonium chloride, benzalkonium chloride, cetylpyridium chloride, N-alkyl-N,N-dimethylglycine, lauryldimethylaminoacetic acid betaine, 2-alkyl-N- Examples include amphoteric surfactants such as carboxymethylhydroxyethylimidazolinium betaine and sodium β-laurylaminopropionate, which can be used alone or in combination of two or more. Further, as the polymerization initiator, an initiator soluble in a hydrophobic monomer is selected and used, and examples thereof include benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and cumene hydroperoxide. Ru. A polymerization reaction is carried out using the main raw materials configured as described above, and a spherical polymer having spherical vacuoles is obtained. In other words, a radical polymerization reaction is caused by using an emulsifier as in emulsion polymerization and a polymerization initiator soluble in monomers as in suspension polymerization. An essential condition is to form a phase (hereinafter abbreviated as W/M/W) type multiple emulsion. Furthermore, the formed W/M/W type multiple emulsion needs to be stable until the polymerization reaction progresses sufficiently to form a polymer. For this purpose, we formed W/M/
Depending on the disappearance rate of the W-type multiple emulsion, a polymerization initiator having an appropriate decomposition rate is selected and temperature conditions are set. Next, the general manufacturing process according to the present invention is shown. In an aqueous phase containing an ionic surfactant maintained at an appropriate temperature under inert gas substitution such as nitrogen,
A method is used in which a monomer phase containing a nonionic surfactant and a vertical and horizontal initiator is dispersed under stirring, a W/M/W type emulsion is formed all at once, and the emulsion is further polymerized. Of course, for the purpose of controlling apparent specific gravity, average particle diameter, number of vacuoles, etc.
First, a W/M type emulsion is created by adding an aqueous phase, which is to become the innermost phase, to the monomer phase, and then it is dispersed in the aqueous phase, which is the outermost phase, to form a W/M/W emulsion, and then polymerized. It goes without saying that the two-step method is possible, but the one-step method is industrially more advantageous because it shortens the process and simplifies equipment. In addition, as a method for adding a polymerization initiator, a method called post-addition is also used in normal emulsion polymerization, but in the method of the present invention, a monomer-soluble polymerization initiator is used, so there is a risk of a decrease in initiator efficiency, etc. However, it cannot be said that it is a very preferable method. The ratio of the monomer phase and water phase mixed here is 1:
3 to 1:30, more preferably 1:4 to 1:25. When the ratio of the aqueous phase to the monomer phase becomes less than 3 times, the polymerization reaction rapidly progresses, and the entire system becomes thickened or gelled.
Since it becomes difficult to control the reaction heat, abnormal temperature rise may cause deterioration in the quality of the spherical polymer and failure of the reaction apparatus. Moreover, if it exceeds 30 times, the yield, productivity, etc. will decrease. W/M/W after the polymerization reaction was completed as described above.
Since the multi-type emulsion becomes a spherical polymer containing vesicles and is dispersed in the aqueous phase, the solid content is removed by centrifugation, vacuum or pressurization, decantation, etc. and washed. The solvent used for washing may be water or an organic solvent that serves as a non-solvent for the spherical polymer, and may be used alone or in the form of a mixed solvent. At this time, a monomer to serve as a crosslinking agent, such as a combination of methyl methacrylate and ethylene glycol dimethacrylate or a combination of styrene and divinylbenzene, is added and polymerized to form a polymer.
Since dimensional structures have excellent solvent resistance, the range of solvents used for cleaning can be selected from a wider range. In this washing step, in addition to the ionic surfactant and nonionic surfactant, additive components such as electrolytes, unreacted monomers, and the like are removed.
Further, through a process of removing the solvent used for washing by drying under reduced pressure, hot air drying, etc., a spherical polymer having internal spherical vacuoles and an average particle size of 0.5 to 50 μm is obtained. In other words, the spherical polymer has countless pores large enough for molecules to pass through, and the internal vesicles communicate with the outside world, so when cleaning the spherical polymer, the internal vesicles are also cleaned at the same time. As a result, drying progresses simultaneously inside and outside. This is the greatest advantage of the production method of the present invention, which uses a W/M/W type multiple emulsion in which both the innermost and outermost phases are aqueous phases. Another advantage of the production method of the present invention is that the average particle diameter of the spherical polymer and the number of vacuoles present inside the spherical polymer can be easily controlled. That is, by appropriately selecting and balancing the combination of the nonionic surfactant contained in the monomer phase and the ionic surfactant contained in the aqueous phase, a W/M/W type multiple emulsion is formed. Compared to adjusting the particle size only by stirring conditions, dropping conditions, etc., it is much easier to adjust the particle size.
Similarly, the number of water droplets contained within a monomer droplet can also be adjusted. For example, when sodium dioctyl sulfosuccinate is added to the aqueous phase, when polyoxyethylene sorbitan monoolefinate is added to the monomer phase, 1 drop per monomer drop.
Only multiple emulsions containing 1,000 water droplets are formed, whereas addition of sorbitan trioleate results in multiple emulsions containing several tens of water droplets per monomer drop. Furthermore, the number of water droplets contained in the monomer droplets can be adjusted by changing the rate at which the monomer phase is added to the aqueous phase or the emulsifier concentration. Furthermore, although it is a secondary feature, polyhydric alcohols, electrolytes, PH regulators, etc. can be added to the aqueous phase within a range that does not destroy the W/M/W type multiple emulsion, so the state of the system can be controlled and used for the intended purpose. It is also possible to obtain spherical polymers with spherical vacuoles that meet the requirements. Here, examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol,
1,3-butanediol, sorbitol, xylide, D-mannite, maltitol, glucose,
Examples include sucrose. Examples of the electrolyte include sodium chloride, calcium chloride, sodium carbonate, sodium polyphosphate, and sodium metaphosphate. As the PH regulator, in addition to bases such as hydrochloric acid, sulfuric acid, acetic acid, sodium hydroxide, potassium hydroxide, aqueous ammonia, and the like, known buffers can also be used. As described above, the spherical polymer having spherical vacuoles inside produced by the production method of the present invention can freely control the size and number of spherical vacuoles, so it not only reduces the apparent specific gravity but also Compared to those with the same composition that are dense to the center or porous, they not only have superior light transmittance, but also have the ability to provide various changes in reflectivity and refraction as needed.
Combined with its elastic properties, it can be used as a completely new material for cosmetic fuels. It should be noted that the spherical polymer obtained by the method of the present invention is similar to conventional commercially available spherical particles (manufactured by Nippon Chemical Co., Ltd.,
MMA/EDMA type, average particle size approximately 10μ, non-porous) (Figure 1) and porous particle (manufactured by Nippon Chemical Co., Ltd., MMA/EDMA type, average particle size approximately 10μ, porous) (Figure 2). In order to show whether the structures are different, Example 2 (MMA/EDMA system, average particle diameter of about 17μ, number of spherical vacuoles: 1) (Figure 3) and Example 5 (MMA/EDMA system, average particle system of approx. 28μ,
The difference is shown with a micrograph (magnification x 100) along with a large number of spherical vacuoles (Figure 4). Similarly, in order to prove the excellent light transmittance of the spherical polymer obtained by the method of the present invention, a comparative test of light transmittance in the visible region was conducted, and the results are shown in Table 1. <Measurement method> Sample: Commercially available spherical particles (above) Commercially available porous particles (above) Example 2 Spherical polymer Measuring equipment: Hitachi model 323 self-recording spectrophotometer Sample preparation: Liquid paraffin for 20 parts of each sample
Make a paste by adding 80 parts and apply this on the glass cell (however, only liquid paraffin is used for reference). Measurement wavelength: 470nm (blue region), 530nm (edge region) 660nm (red region) Measurement value: Transmittance (%)

[Table] As is clear from the results in Table 1, the spherical polymer obtained by the method of the present invention has significantly superior translucency compared to commercially available spherical particles, and
As can be understood from the figure, since the inside is hollow, it is possible to obtain a product with excellent elasticity by controlling the degree of hollowness. It goes without saying that the spherical polymer of the present invention also has other properties (rollability, dispersibility, etc.) that conventional spherical particles have. Next, examples of the present invention will be shown. The blending ratios are parts by volume (ml) for the monomer and parts by weight (g) for the other components. Example 1 A Sodium lauryl sulfate Sodium hexamethanate water 0.50 2.25 447.25 B Methyl methacrylate ethylene glycol dimethacrylate Benzoyl peroxide Sorbitan monooleate 21.00 8.00 0.15 4.50 (Method) Condenser, stirrer, thermometer, nitrogen inlet A was charged and dissolved in the reactor equipped. After B was dissolved at room temperature, A was gradually added to the mixture while stirring. The temperature was maintained at 65° C. while being careful to keep the inside of the reactor constantly filled with nitrogen, and the polymerization reaction was carried out for 4 hours and then stopped. After the contents were filtered under reduced pressure, they were thoroughly washed with water, replaced with isopropyl alcohol and then hexane, and dried. The resulting spherical polymer has an average particle size of 19μ and a specific gravity of
0.58 and had one spherical vacuole inside. Example 2 A Sodium dioctyl sulfosuccinate Sodium hexametaphosphate aqueous 2.70 0.50 446.80 B Methyl methacrylate ethylene glycol methacrylate Benzoyl peroxide polysorbate 80 63.00 27.00 0.45 8.10 (Method) Produced in the same manner as in Example 1. The resulting spherical polymer has an average particle size of 17μ and a specific gravity of
0.52 and had one spherical vacuole inside. Example 3 A Sodium dioctyl sulfosuccinate Sodium hexametaphosphate aqueous 2.70 0.50 446.80 B Methyl methacrylate ethylene glycol methacrylate Benzoyl peroxide polyoxyethylene cetyl ether 21.00 9.00 0.15 2.70 (Method) Produced in the same manner as in Example 1. The resulting spherical polymer has an average particle diameter of 22μ and a specific gravity of
0.69, and had several dozen spherical vacuoles inside. Example 4 A Sodium dioctyl sulfosuccinate Sodium hexametaphosphate aqueous 2.70 0.50 446.80 B Methyl methacrylate Vinyl acetate ethylene glycol methacrylate Benzoyl peroxide Sorbitan monooleate 21.00 10.00 9.00 0.20 1.20 (Method) Produced in the same manner as in Example 1. The resulting spherical polymer had an average particle diameter of 20μ, a specific gravity of 0.73, and several dozen spherical vacuoles inside. Example 5 A Sodium dioctyl sulfosuccinate Sodium hexametaphosphate aqueous 2.70 0.50 446.80 B Methyl ethylene glycol methacrylate methacrylate Benzoyl peroxide Sorbitan monooleate 21.00 9.00 0.15 2.70 C Water 110.00 (Method) A was charged into the same reactor as in Example 1. It was dissolved in After dissolving B, C was gradually added while stirring to obtain a W/M type emulsion. This was put into stirring A to form a W/M/W type multiple emulsion. The subsequent operations were carried out in the same manner as in Example 1. The resulting spherical polymer has an average particle diameter of 28μ and a specific gravity of
It had a diameter of 0.77 and had several dozen spherical vacuoles inside. Example 6 Instead of adding B all at once in Example 2,
It was added dropwise over 15 minutes. The resulting spherical polymer has an average particle size of 13μ and a specific gravity of
0.47, and had one spherical vacuole inside. Example 7 Instead of adding B all at once in Example 2,
It was added dropwise over 30 minutes. The resulting spherical polymer has an average particle size of 14μ and a specific gravity of
It had a diameter of 0.72 and had 3 to 4 spherical vacuoles inside.

[Brief explanation of drawings]

Figure 1 shows commercially available spherical particles (manufactured by Nippon Chemical Co., Ltd.,
Microscope photo of MMA/EDMA type, average particle size approximately 10μ, non-porous). Figure 2 is a micrograph of commercially available porous particles (manufactured by Nippon Chemical Co., Ltd., MMA/EDMA type, average particle size approximately 10μ, porous). Figure 3 is a micrograph of the spherical polymer of Example 2 (MMA/EDMA system, average particle size of approximately 17μ, number of spherical vacuoles: 1), and Figure 4 is a photomicrograph of the spherical polymer of Example 5 (MMA/
Microscopic photograph of EDMA type, average particle diameter approximately 28μ, many spherical vacuoles). The magnification for both images is ×100. In addition, in the micrograph, the black parts seen inside the particles indicate vacuoles or pores where air exists.

Claims (1)

[Claims] 1. When polymerizing one or more raw material monomers selected from hydrophobic monomers in an aqueous dispersion medium, a nonionic surfactant is added to the monomer phase and a nonionic surfactant is added to the aqueous phase. A spherical vacuole characterized by containing an ionic surfactant to form an aqueous phase/monomer phase/aqueous phase multiple emulsion and then polymerizing it with a polymerization initiator soluble in a hydrophobic monomer. A method for producing a spherical polymer having 2. Claim 1, wherein the spherical polymer has an average particle diameter of 0.5 to 50μ and an apparent specific gravity of 0.8 or less.
A method for producing a spherical polymer having spherical vacuoles as described in . 3. The method for producing a spherical polymer having spherical vacuoles according to claim 1, wherein the number of spherical vacuoles present inside the spherical polymer is one or two or more.