JP2008101119A - Method for producing vinyl resin particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing vinyl resin fine particles having a dent on the surface of the particle, wherein the method for producing vinyl resin fine particles can economically produce the resin particles without using any complex production step. <P>SOLUTION: The method for producing vinyl resin particles having dent of 1-200 μm average particle diameter on the surface comprises a dispersing step for preparing a mixture liquid finely dispersed with drops of the vinyl monomer by agitating the vinyl monomer containing a plasticizer in an aqueous medium, and a polymerizing step for polymerizing in a reactor the vinyl monomer in the mixture liquid, wherein vinyl monomer in the dispersing step is added with one or more selected from the group consisting of a fatty acid ester, a liquid paraffin and an olefin as the plasticizer at a ratio of 0.1-3 pts.wt. per 100 pts.wt. vinyl monomer, and in the polymerizing step, a hydrocarbon having 13-17 (MPa)<SP>1/2</SP>solubility parameter is added into the mixture solution, on the condition that the polymerization conversion of the vinyl monomer is 40-98%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing vinyl resin fine particles, and more particularly to a method for producing vinyl resin particles having a depression on the surface and an average particle diameter of 1 to 200 μm.

In recent years, resin fine particles having an average particle size of several μm to several tens of μm have been used for various purposes in fields such as paints, cosmetics, and light diffusing agents.
However, since the shape of commonly used resin fine particles is a true sphere, it is necessary to improve the functions such as the matte and concealing properties of the paint and the scattering and adhesion properties of cosmetics. There was room for improvement.

  Therefore, in order to further improve the function of the spherical resin fine particles, development of resin fine particles having depressions on the surface has been attempted. However, there are many particles in which the obtained particles are porous or the shape of the dent is distorted. On the other hand, it has become possible to obtain resin fine particles having good depressions on the surface by the method disclosed in Patent Document 1. In the method of Patent Document 1, in the absence of a crosslinking agent, 100 parts by weight of the polymerizable vinyl monomer does not have a copolymerizability with the polymerizable vinyl monomer, and the viscosity at 25 ° C. is less than 0.1 to 3 cSt. 3 to 40 parts by weight of the hydrophobic fluorine-based liquid organic compound is dissolved and subjected to aqueous suspension polymerization to obtain spherical resin particles having a bowl-shaped depression on the surface thereof. However, since this method uses a special fluorinated liquid compound, it requires a separation operation between the resin particles and the fluorinated compound in the end, so that it can be produced and used on an industrial scale. There was a cost difficulty.

JP 2002-88102 A

  The present invention has been made in order to solve the above-described conventional problems, and is a method for producing vinyl resin fine particles having depressions on the particle surface, which does not go through complicated production steps and is inexpensive. It aims at providing the manufacturing method of the vinyl resin fine particle which can manufacture particle | grains.

  As a result of various studies to solve the above problems, the present inventors finely disperse the vinyl monomer droplets by stirring the vinyl monomer containing the specific plasticizer at high speed. When the resin particles are polymerized while the mixture is stirred in the reactor, a specific hydrocarbon is added with the conversion rate of the polymerization reaction as a guideline. The inventors have found that resin fine particles can be produced, and reached the present invention.

That is, according to this invention, the manufacturing method of the vinyl resin particle shown below is provided.
[1] A dispersion step of stirring a vinyl monomer containing a plasticizer in an aqueous medium to obtain a mixed liquid in which droplets of the vinyl monomer are finely dispersed; A method for producing vinyl resin particles having an average particle diameter of 1 to 200 μm having depressions on the particle surface, the polymerization step comprising polymerizing a vinyl monomer of
In the vinyl monomer in the dispersion step, one or more selected from the group of fatty acid ester, liquid paraffin, or olefin as a plasticizer is added in an amount of 0.001 part by weight based on 100 parts by weight of the vinyl monomer. 1-3 parts by weight are added,
In the polymerization step, a hydrocarbon having a solubility parameter of 13 to 17 (MPa) ^1/2 is added to the mixed solution in a state where the polymerization conversion rate of the vinyl monomer is 40 to 98%. A method for producing vinyl resin particles.
[2] The method for producing vinyl resin particles as described in [1] above, wherein the amount of the hydrocarbon added is 1 to 30 parts by weight with respect to 100 parts by weight of the vinyl monomer.
[3] The method for producing vinyl resin particles according to [1] or [2], wherein the hydrocarbon has a boiling point of less than 80 ° C.
[4] The above [1] to [3], wherein the vinyl monomer comprises an acrylate ester or one or more vinyl monomers other than the acrylate ester and the acrylate ester. The manufacturing method of the vinyl-type resin particle in any one of.
[5] The method for producing vinyl resin particles according to [4], wherein the vinyl monomer is composed of methyl methacrylate, styrene, and α-methylstyrene.

  According to the production method of the present invention, in the dispersion step, the vinyl monomer having a specific amount of a specific plasticizer added is dispersed, and in the polymerization step, a specific hydrocarbon is added and the hydrocarbon is added. By adjusting the addition time and polymerizing the vinyl monomer, vinyl resin particles having an average particle diameter of 1 to 200 μm and having depressions on the surface can be easily obtained. According to the production method of the present invention, it is possible to obtain vinyl resin particles having depressions on the surface without using a special fluorinated liquid compound such as that employed in Patent Document 1. There is no need for a complicated process such as a separation operation with a compound. Therefore, vinyl resin particles having a depression on the surface can be produced in large quantities and at low cost on an industrial scale. In addition, according to the present invention, the number and size of the depressions formed on the surface of the resin particles can be easily adjusted by adjusting the timing of addition of the specific hydrocarbon in the polymerization step. Resin particles that can be adapted to the demands of fields, medical fields, chemical fields, cosmetics fields, and other industrial fields can be easily provided.

Hereinafter, the manufacturing method of the vinyl resin particle of this invention is demonstrated in detail.
The method for producing vinyl resin particles (hereinafter also simply referred to as resin particles) of the present invention comprises 1) a dispersion step and 2) a polymerization step, and through these steps, the average particle size becomes 1. Resin particles having a diameter of ˜200 μm and having depressions on the surface are obtained.

  The 1) dispersing step is a step of stirring the vinyl monomer in an aqueous medium to obtain a mixed liquid in which droplets of the vinyl monomer are finely dispersed, and 2) polymerization. The step is a step of polymerizing the vinyl monomer in the mixed solution in the reactor. Examples of the method for producing resin particles comprising 1) a dispersion step and 2) a polymerization step include an emulsion polymerization method, a suspension polymerization method, a seed polymerization method, etc. Among them, the suspension weight as shown below as a specific example. Legal is preferred. First, 1) In the dispersion step, an aqueous medium, a suspending agent and an anionic surfactant are charged into a container equipped with an emulsifying device, and then a vinyl monomer and a polymerization initiator are charged. The vinyl monomer is dispersed as a fine liquid in an aqueous medium by high-shear stirring in the emulsifying device to form an emulsified liquid. 2) In the polymerization step, the emulsified liquid is put into a reactor equipped with a stirrer. Then, after removing oxygen in the reactor by nitrogen substitution, the reactor is heated with stirring, and the vinyl monomer is polymerized at a predetermined temperature for a predetermined time. In the present specification, the suspension polymerization method will be described below as an example, but vinyl resin particles having depressions on the surface of the resin particles can naturally be produced in other polymerization methods based on the technique of the present invention.

  Examples of the aqueous medium used in the present invention include deionized water and pure water.

  Examples of the vinyl monomer used in the present invention include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, vinyl toluene, p-ethyl styrene, and 2,4-dimethyl styrene. , P-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, pn-hexylstyrene, p-octylstyrene, styrenesulfonic acid, styrene Vinyl aromatic compounds such as sodium sulfonate; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethyl methacrylate Acrylic acid esters sill like; acrylonitrile, methacrylonitrile group-containing unsaturated compounds such as nitrites and the like.

  The vinyl monomer is used alone or in combination of two or more depending on the intended use of the resin particles obtained. In addition, since it becomes easy to adjust the number and size of the dents on the surface of the resin particles in the present invention, the vinyl monomer may be the acrylic ester or 1 other than the acrylic ester and the acrylic ester. A combination with at least one kind of vinyl monomer is preferable, and methyl methacrylate, styrene and α-methylstyrene are preferably used in combination. In this case, as a blending amount, in the combination of the acrylic ester and one or more vinyl monomers other than the acrylic ester, the acrylic ester is 50 to 100% by weight, and other vinyl single monomers. The body is preferably 0 to 50% by weight (however, the total of these is 100% by weight). In the combination of methyl methacrylate, styrene and α-methylstyrene, 50% by weight or more of methyl methacrylate Less than 100% by weight, more than 0% by weight of styrene and less than 50% by weight, and more than 0% by weight of α-methylstyrene and 15% by weight or less (however, the total of these is 100% by weight) are preferable.

  Examples of the polymerization initiator used in the present invention include azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, t Examples thereof include initiators soluble in monomers such as butyl peroxybenzoate, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, lauroyl peroxide. Usually, the amount of the polymerization initiator is preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the total weight of the charged vinyl monomer.

  In the present invention, in order to adjust the molecular weight of the obtained resin particles, for example, a chain transfer agent such as n-dodecyl mercaptan or α-methylstyrene dimer may be added to the vinyl monomer.

  Examples of the suspension added in the present invention include tricalcium phosphate, hydroxyapatite, magnesium pyrophosphate, magnesium phosphate, aluminum hydroxide, ferric hydroxide, titanium hydroxide, and magnesium hydroxide. And fine particulate water-insoluble inorganic salts such as barium phosphate, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, talc, kaolin and bentonite. More preferred are tricalcium phosphate, hydroxyapatite, and magnesium pyrophosphate.

  The amount of the suspending agent used is usually 0. 0 as a solid content with respect to 100 parts by weight of an aqueous medium of a suspension polymerization system (referring to all water in the system including water such as a reaction product-containing slurry). 05 to 20 parts by weight, preferably 0.3 to 15 parts by weight. If the amount is less than 0.05 parts by weight, the vinyl monomer cannot be suspended and stabilized, and a resin mass may be generated. If the amount exceeds 20 parts by weight, it is not preferable from the viewpoint of production cost. In addition, the problem that the particle size distribution becomes wide is likely to occur.

  Examples of the anionic surfactant added in the present invention include sodium alkyl sulfonate, sodium alkylbenzene sulfonate, sodium lauryl sulfate, sodium α-oleate sulfonate, sodium dodecylphenyl oxide disulfonate, dipotassium alkenyl succinate and the like. Can be mentioned. Preferably, it is an alkylsulfonic acid alkali metal salt (preferably sodium salt) having 8 to 20 carbon atoms, more preferably an alkali metal laurylsulfonic acid salt (preferably sodium salt). Thereby, the effect of the outstanding suspension stabilization is acquired. Moreover, electrolytes, such as inorganic salts, such as lithium chloride, potassium chloride, sodium chloride, sodium sulfate, sodium nitrate, sodium carbonate, sodium bicarbonate, can be added to a suspending agent as needed.

  The average particle diameter of the resin particles obtained by the method of the present invention is 1 to 200 μm. In order to adjust the average particle diameter within this range, the dispersion state of the vinyl monomer may be controlled by the type and amount of an anionic surfactant added to the suspending agent, stirring conditions, and the like. As a matter of course, the average particle diameter can be adjusted by classifying the obtained resin particles.

  The average particle diameter of the resin particle in this specification means a volume average particle diameter. The volume average particle size is determined by dispersing resin particles in water and measuring the particle size distribution by a laser diffraction scattering method (Microtrack MT-3300EX manufactured by Nikkiso Co., Ltd.), and the cumulative volume with respect to the volume of all particles is 50%. It is determined as the particle size of time.

In order to obtain resin particles having depressions on the surface of the resin particles, 1) one or more plasticizers selected from the group of fatty acid esters, liquid paraffin, and olefins as vinyl monomers in the dispersion step Is required to be added in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the vinyl monomer, and 2) the polymerization conversion rate of the vinyl monomer in the polymerization step is 40 to 98. %, It is necessary to add a hydrocarbon having a solubility parameter of 13 to 17 (MPa) ^{1/2 as} a deforming agent to the mixed solution.

  As described above, the plasticizer-containing vinyl monomer used in the dispersion step 1) includes one or more selected from the group of fatty acid ester, liquid paraffin, and olefin as the plasticizer. Among them, fatty acid esters are preferably used from the viewpoint that the density, depth, and diameter of the opening can be adjusted relatively easily. The density, depth, and diameter of the opening will be described later in detail.

  Examples of the fatty acid ester include hexadecyl 2-ethylhexanoate, methyl palm fatty acid, methyl laurate, isopropyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, beef tallow fatty acid methyl, octyldodecyl myristate, methyl stearate, stearic acid Butyl, 2-ethylhexyl stearate, isotridecyl stearate, methyl caprate, methyl myristate, methyl oleate, isobutyl oleate, octyl oleate, lauryl oleate, oleyl oleate, myristyl myristate, stearyl stearate, oleic acid Esters of fatty acids such as 2-ethylhexyl, decyl oleate, isobutyl oleate and monohydric alcohols, sorbitan monolaurate, sorbitan monopa Mitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, pentaerythritol monostearate, glycerin Examples include esters of fatty acids and polyhydric alcohols such as monostearate, glycerol distearate, glycerol tristearate, glycerol monooleate, glycerol tri-2-ethylhexarate, hydrogenated beef tallow, hydrogenated castor oil. Moreover, these fatty acid esters can be used alone or in combination.

Among these fatty acid esters, it is preferable to use glycerin tristearate because resin particles having a dent density of 0.5 / 100 μm ² or more and a dent depth of 0.05 μm or more can be easily obtained.

As examples of the liquid _{paraffin, C m H n (n <} 2m + 2, m is the number of carbon atoms) include branched structure, alicyclic hydrocarbon compounds having a cyclic structure or mixtures thereof represented by. From the viewpoint of adjusting the size and number of the recesses, the average carbon number of the liquid paraffin is preferably 10 to 40, and particularly preferably 20 to 35. If the carbon number is too small, it is difficult to form a recess. On the other hand, if the carbon number is too large, the diameter of the opening of the recess tends to be small.

  Moreover, as said olefin, although a C10-C40 olefin or a mixture thereof is meant, a C15-C35 thing or a mixture thereof is preferable. As the olefin, α-olefin is particularly preferable. When the number of carbon atoms of the olefin is too small, it is difficult to form a recess. On the other hand, when the number of carbon atoms is too large, the diameter of the opening of the recess tends to be small.

The addition amount of the plasticizer (the total addition amount when a plurality of plasticizers are used) is 0.1 to 3 parts by weight, preferably 0.3 to 2 parts per 100 parts by weight of the vinyl monomer. Parts by weight. Within this range, a plurality of depressions can be easily formed on the surface of the obtained resin particles. If it is less than 0.1 part by weight, there is a possibility that the object of forming a depression on the surface of the resin particle cannot be achieved. On the other hand, if it exceeds 3 parts by weight, the suspension system becomes unstable and the resin particles may be condensed during the polymerization.
The method for adding the plasticizer to the vinyl monomer is not particularly limited, but a method in which a predetermined amount is added and dissolved in advance in the vinyl monomer used for the polymerization is preferable.

In 2) polymerization step of the present invention, act together with the plasticizer as a hydrocarbon to form a recess (deformed agent), solubility parameter (hereinafter, also referred to as SP value.) Is 13 to 17 (MPa) ^{1 / 2} , preferably 14 to 16 (MPa) ^1/2 of hydrocarbon is used. Examples of the hydrocarbon having an SP value of 13 to 17 (MPa) ^1/2 include butane, pentane, hexane, heptane, octane, cyclopentane, cyclohexane, decane, and limonene, among which pentane and limonene are vinyl. From the viewpoint of compatibility with the monomer.

The SP value in this specification corresponds to the square root of the cohesive energy density between molecules, and this value is necessary for physically evaporating a 1 cm ³ liquid as shown in the following equation (1). It is a numerical value indicating the magnitude of the polarity per unit volume by a value obtained by raising the energy amount to a power of 1/2. SP value in this specification shall be a value calculated | required based on following (1) Formula.
SP value (MPa) ^1/2 = (ΔE / V) ^1/2 = ((ΔH−RT) / V) ^1/2
= (((ΔH−RT) d / M) ^1/2 (1)
ΔE: evaporation energy (J / mol), V: molecular volume (cm ³ / mol), ΔH: latent heat of evaporation (J / mol), R: gas constant = 8.314 J / (mol · K), T: Absolute temperature (K), d: density (g / cm ³ ), M: molecular weight (g / mol)

  Moreover, it is preferable that the boiling point of the hydrocarbon used by this invention is less than 80 degreeC. When the boiling point is less than 80 ° C., hydrocarbons can be easily removed from the obtained resin particles, and the remaining of the hydrocarbons in the resin particles can be suppressed as much as possible.

In the polymerization step 2) of the method of the present invention, the hydrocarbon is added to the mixed solution in the reactor with the polymerization conversion rate of the vinyl monomer being 40 to 98%, preferably 40 to 80%. The
In addition, the specific temperature and time reaction condition adjustment for setting the polymerization conversion rate of adding 40% to 98% of the hydrocarbon to the mixed solution is generally determined by the blending of various compositions, the polymerization conditions, and the like. For example, (1) While stirring the slurry in the reactor, the temperature is raised to approximately 80 ° C. at 0.4 to 0.8 ° C./min, and then stirred at that temperature for 3 to 9 hours. (2) While stirring the slurry in the reactor, the temperature is raised to approximately 80 ° C. at 0.4 to 0.8 ° C./min, and then the heating rate is decreased to approximately 115 ° C. Hold with stirring over 3 to 9 hours while raising the temperature, or (3) After raising the temperature to about 80 ° C. at a rate of 0.4 to 0.8 ° C./min while stirring the slurry in the reactor , Slow down the heating rate, further increase the temperature to approximately 115 ° C, and hold at that temperature with stirring Together operation of the 80 ° C. after arrival can be adjusted such as by performing over 3-9 hours.

In addition, the polymerization conversion rate in this invention can be calculated | required as follows.
About 5 g of soot-like polymer is taken out from the reactor before adding the hydrocarbon to the filter paper, the polymer is lightly pressed with the filter paper, and moisture is sucked into the filter paper. About 1.5 g of cocoon-shaped polymer is taken from a filter paper in a 20 ml beaker and weighed (g) to 4 digits after the decimal point to obtain “weight before reprecipitation”.
Next, chloroform is added to the polymer in a 20 ml beaker at a ratio of 5 to 6 ml of chloroform with respect to 1 g of polymer (100% purity), and the polymer is dissolved in chloroform. 120-130 ml of methanol is put into a separately prepared 200 ml beaker, and the previously prepared chloroform solution is dropped little by little into the beaker containing methanol while stirring with a stirrer chip. Finally, 10 ml of methanol is poured into a 20 ml beaker, the polymer attached to the vessel wall is collected, and the solution is added to the 200 ml beaker. The solution in the 200 ml beaker is then stirred for several hours and then filtered to recover the polymer. The recovered polymer is air-dried and then dried in a vacuum dryer at 80 ° C. for 1 day or more. The recovered amount of the polymer obtained by this operation is weighed (g) to 4 digits after the decimal point to obtain “weight after reprecipitation”.

By substituting the “weight before reprecipitation” and “weight after reprecipitation” obtained as described above into the following equation (2), the polymerization conversion rate (%) can be obtained.
Polymerization conversion rate (%) = (“weight after reprecipitation” / “weight before reprecipitation”) × 100 (2)

When the polymerization conversion is less than 40% and a hydrocarbon is added or when a hydrocarbon having an SP value of less than 13 (MPa) ^1/2 is used, phase separation described later hardly occurs, and the surface of the resin particle is depressed. Some resin particles may not be obtained. On the other hand, even when the polymerization conversion rate exceeds 98%, there is a possibility that resin particles having dents on the surface of the resin particles cannot be obtained. In addition, when hydrocarbons having an SP value of more than 17 (MPa) ^1/2 are used, the resin particles may aggregate, and in a severe case, the particles may solidify and be integrated and condensed.

  The amount of the hydrocarbon added to the mixed solution is preferably 1 to 30 parts by weight, more preferably 3 to 20 parts by weight, and particularly 4 to 17 parts by weight with respect to 100 parts by weight of the vinyl monomer. preferable. If the amount of the hydrocarbon added is too small relative to 100 parts by weight of the vinyl monomer, phase separation described later is unlikely to occur, and resin particles having dents on the surface of the resin particles may not be obtained. If the amount of the hydrocarbon added is too large, the suspension system may become unstable and resin particles may not be obtained.

As a method for adding the hydrocarbon to the mixed solution, it may be supplied continuously or intermittently. Moreover, the diameter of the opening part of a hollow, the depth of a hollow, and the density of a hollow can be adjusted with the kind of hydrocarbon, addition amount, addition time, and addition speed. Specifically, by using a hydrocarbon having an SP value of 13 to 17 (MPa) ^{1/2 as} a hydrocarbon, an amount of hydrocarbon necessary for causing phase separation is easily absorbed by the resin particles. Increasing the amount of the hydrocarbon added can cause the resin particles to absorb an amount of hydrocarbons necessary to cause phase separation. However, if the amount is too large, the resin particles will aggregate, and if it is severe, they will consolidate and aggregate. There is a risk that. In addition, if the addition timing of the hydrocarbon is advanced, it is possible to secure a sufficient time for the resin particles to absorb an amount of hydrocarbon necessary for causing phase separation. On the other hand, if the addition timing of the hydrocarbon is too late, it is not possible to secure a sufficient time for the resin particles to absorb the amount of hydrocarbon necessary to cause phase separation. Further, if the addition rate of the hydrocarbon to the mixed solution is increased, it becomes easy for the resin particles to absorb an amount of hydrocarbon necessary for causing phase separation. Further, in relation to the diameter of the dent opening, the depth of the dent, and the density of the dent, the larger the SP value of the hydrocarbon, the greater the amount added, the earlier the addition time, the faster the addition rate, There is a tendency that the diameter of the recesses increases, the depth of the recesses increases, and the density of the recesses decreases.

  In the present invention, the mechanism for obtaining vinyl resin particles having a plurality of depressions on the particle surface is not clear, but the hydrocarbon dissolved in the monomer or polymer and the plasticizer are polymerized as the polymerization proceeds. It is presumed that the phase and the phase of the hydrocarbon or plasticizer undergo phase separation, the hydrocarbon or plasticizer is removed, and the trace becomes a depression. In the present invention, in order to control the state of phase separation, α-methylstyrene or α-methylstyrene dimer is used to control the polymerization rate and polymer viscosity, but the chain other than α-methylstyrene dimer is used. It is also possible to adjust by using a transfer agent or changing the type and amount of the polymerization initiator or the polymerization temperature condition.

Next, the vinyl-type resin particle which has a hollow in the resin particle surface obtained by the method of this invention is explained in full detail.
As shown in the conceptual diagram of FIG. 1, the vinyl resin particles obtained by the method of the present invention have depressions on the surface thereof. As shown in FIGS. 2 to 4, the shape of the dent is a substantially circular dent shape, which is like a crater. One or more, preferably a plurality of such depressions are formed on the surface of the resin particles with respect to one resin particle.

The average number of depressions of the resin particles formed according to the present invention is generally 1.0 to 200, and preferably 1.2 to 20 depending on the use of the resin particles. The diameter of the opening of the depression is approximately 0.1 to 15 μm, and is preferably 0.8 to 10 μm although it depends on the use of the resin particles. The depth of the recess of the resin particles is approximately 0.03 to 5 μm, and is preferably 0.05 to 3 μm although it depends on the use of the resin particles. Density of the recess of the resin particles is roughly from 0.3 to 200 pieces / 100 [mu] m ^2, depending on the application of the resin particles is preferably 0.5 to 20 pieces / 100 [mu] m ^2.

  The average number of depressions is a value calculated as an arithmetic average value of the values obtained by measuring the number of depressions on the surface of resin particles for 20 arbitrary resin particles. Specifically, the surface of the vinyl-based resin particles was magnified 2000 times with a scanning electron microscope and photographed, and the number of each depression was measured for 20 arbitrary resin particles. It is a value calculated as an arithmetic average value of the number of depressions.

  The diameter of the opening of the dent is a value calculated as an arithmetic average value of the values obtained by measuring the diameter of the opening at 20 arbitrary dents on the surface of the resin particles. Specifically, the surface of the vinyl resin particles is magnified 2000 times with a scanning electron microscope and photographed, the maximum diameter is measured for any 20 recessed openings, and the arithmetic of the measured 20 diameters is performed. It is a value calculated as an average value.

  The depth of the dent is a value calculated as an arithmetic average value of values obtained by measuring the depth of the dent at 20 arbitrary dents on the surface of the resin particles. Specifically, the resin particles were photographed with a nanoscale hybrid microscope at a magnification of 1250 times, and the maximum depth of the dent was measured arbitrarily at 20 locations by the amount of deflection of the cantilever (20 nm), and 20 locations were measured. It is a value calculated as an arithmetic average value of the depth of.

The density of the depressions was measured by measuring the number of depressions on the surface of each resin particle with respect to 20 arbitrary resin particles by taking a photograph by enlarging the surface of the resin particles 2000 times with a scanning electron microscope. the surface area of the resin particles was calculated based on the diameter of the resin particles, and calculates the number of depressions of the surface area of 100 [mu] m ² per each of the resin particles, the surface area of 100 [mu] m ² per calculated 20 resin particle indentations number of It is a value calculated as an arithmetic average value.

  The vinyl-based resin particles having depressions on the surface obtained by the present invention can be used as additives for light diffusing agents, cosmetics, latencies, paints, etc., and for various applications that make use of the functionality by having depressions. It can be used.

  Hereinafter, the present invention will be described in detail with reference to specific examples. However, the present invention is not limited to the examples.

Example 1
1 kg of deionized water was put into a 3 L reactor (autoclave) equipped with a stirring blade, and 16.2 g of sodium pyrophosphate was added and dissolved, and then 37.5 g of powdered magnesium nitrate hexahydrate was added. In addition, the mixture was stirred at room temperature for 30 minutes to synthesize magnesium pyrophosphate as a suspending agent to prepare a reaction product-containing slurry.

  Next, to this reaction product-containing slurry, 5 g of a 10% by weight aqueous solution of sodium lauryl sulfonate, 375 g of methyl methacrylate in advance as a vinyl monomer, 90 g of styrene, and 35 g of α-methylstyrene were added to benzoyl peroxide as a polymerization initiator. 2.5g (NIPPER BW, manufactured by NOF Corporation), 1g of α-methylstyrene dimer (NOFMER MSD manufactured by NOF Corporation) as chain transfer agent, and glycerin tristearate (Japan) as fatty acid ester (plasticizer) After adding a solution in which 5 g of oil and fat (beef tallow extremely hardened oil) was dissolved, the mixed solution was stirred with a homogenizer (manufactured by M Technique Co., Ltd.) at a rotation speed of 10,000 rpm for 10 minutes. The body was finely dispersed.

  Next, after the inside of the autoclave was purged with nitrogen, the temperature was raised while stirring the stirring blade at 200 rpm, and the temperature was raised to 80 ° C. (polymerization start temperature) over 1 hour and a half. After reaching 80 ° C., the temperature was raised to 115 ° C. over 6 hours, kept at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours. In the temperature raising step, 75 g of pentane (a mixture of n-pentane 80% and isopentane 20%) was added as a hydrocarbon (deformation agent) 5 hours after the inside of the autoclave reached 80 ° C. (polymerization start temperature). It was added into the autoclave over about 60 minutes.

After cooling, the contents were taken out, 25 ml of a 67.5 wt% nitric acid aqueous solution was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent attached to the surface of the resin particles. Thereafter, dehydration and washing were performed with a centrifuge, and moisture was removed with a vacuum dryer to obtain resin particles.
In addition, the microscope picture of the resin particle obtained in Example 1 is shown in FIG.

Example 2
Three hours after the inside of the autoclave reached 80 ° C. (polymerization start temperature), 75 g of pentane (a mixture of n-pentane 80% and isopentane 20%) as a hydrocarbon (deformation agent) was placed in the autoclave over 60 minutes. Except for the addition, the same procedure as in Example 1 was performed to obtain resin particles.

Example 3
2.5 g of glyceryl tristearate (beef fat hardened oil from Nippon Oil & Fats Co., Ltd.) as fatty acid ester (plasticizer) and 50 g of butane (mixture of 20% normal butane and 80% isobutane) as hydrocarbon (deformer) are used Except that, resin particles were obtained in the same manner as in Example 1.
In addition, the microscope picture of the resin particle obtained in Example 3 is shown in FIG.

Example 4
Resin particles were obtained in the same manner as in Example 1 except that 10 g of glycerin tri-2-ethylhexalate (Exepal TGO manufactured by Kao Corporation) was used as the fatty acid ester (plasticizer).

Example 5
Resin particles were obtained in the same manner as in Example 1 except that 465 g of methyl methacrylate and 35 g of α-methylstyrene were used as vinyl monomers.

Example 6
Resin particles were obtained in the same manner as in Example 1 except that 1.5 g of glycerin monostearate was used as the fatty acid ester (plasticizer) and 25 g of cyclohexane was used as the hydrocarbon (deformation agent).

Example 7
Autoclave using 285 g of methyl methacrylate, 180 g of styrene, 35 g of α-methylstyrene, 10 g of glyceryl tristearate (beef fat hardened by Nippon Oil & Fats Co., Ltd.) as fatty acid ester (plasticizer) and limonene as hydrocarbon (deformer) The same procedure as in Example 1 was conducted except that 50 g of limonene as a hydrocarbon (deforming agent) was added to the autoclave over 60 minutes after the inside reached 80 ° C. (polymerization start temperature). Resin particles were obtained.

Example 8
The same procedure as in Example 1 was performed except that 5 g of sorbitan monooleate (Emazol O-10 (F) manufactured by Kao Corporation) was used as the fatty acid ester (plasticizer) and 75 g of decane was used as the hydrocarbon (deformer). Resin particles were obtained.
In addition, the microscope picture of the resin particle obtained in Example 8 is shown in FIG.

Example 9
9 hours after the inside of the autoclave reached 80 ° C. (polymerization start temperature), 75 g of pentane (a mixture of n-pentane 80% and isopentane 20%) as a hydrocarbon (deformation agent) was placed in the autoclave over 60 minutes. Except for the addition, the same procedure as in Example 1 was performed to obtain resin particles.

Example 10
Into a reactor (autoclave) having a capacity of 3 L equipped with a stirring blade, 1200 kg of deionized water was added, and 19.4 g of sodium pyrophosphate was further added and dissolved, and then 45 g of powdered magnesium nitrate hexahydrate was added, The mixture was stirred at room temperature for 30 minutes to synthesize magnesium pyrophosphate as a suspending agent to prepare a reaction product-containing slurry.
Next, 6 g of a 10% by weight aqueous solution of sodium lauryl sulfonate, 300 g of methyl methacrylate as a vinyl monomer, and 1.2 g of benzoyl peroxide as a polymerization initiator (Nyper manufactured by NOF Corporation) were added to the reaction product-containing slurry. BW, water-diluted powder product), a solution in which 3 g of glycerin tristearate (beef fat hardened oil manufactured by Nippon Oil & Fats Co., Ltd.) was dissolved as a fatty acid ester (plasticizer) was added, and the mixed solution was homogenized (M Technique Co., Ltd.) In the above, the vinyl monomer was finely dispersed in the slurry.

  Next, after the inside of the autoclave was purged with nitrogen, the temperature was raised while stirring the stirring blade at 200 rpm, and the temperature was raised to 80 ° C. (polymerization start temperature) over 1 hour and a half. After reaching 80 ° C., the temperature was raised to 115 ° C. over 6 hours, kept at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours. In the above temperature raising step, 45 g of pentane (a mixture of n-pentane 80% and isopentane 20%) was added as a hydrocarbon (deformation agent) 5 hours after the inside of the autoclave reached 80 ° C. (polymerization start temperature). It was added into the autoclave over about 60 minutes.

  After cooling, the contents were taken out, 25 ml of a 67.5 wt% nitric acid aqueous solution was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent attached to the surface of the resin particles. Thereafter, dehydration and washing were performed with a centrifuge, and moisture was removed with a vacuum dryer to obtain resin particles.

Comparative Example 1
Two hours after the inside of the autoclave reached 80 ° C. (polymerization start temperature), 75 g of pentane (a mixture of n-pentane 80% and isopentane 20%) as a hydrocarbon (deformation agent) was placed in the autoclave over 60 minutes. Except for the addition, the same procedure as in Example 1 was performed to obtain resin particles. No depression was formed on the surface of the obtained resin particles.

Comparative Example 2
Resin particles were obtained in the same manner as in Example 1 except that 25 g of neopentane was used as the hydrocarbon (deformation agent). No depression was formed on the surface of the obtained resin particles.
In addition, the microscope picture of the resin particle obtained by the comparative example 2 is shown in FIG.

Comparative Example 3
Resin particles were obtained in the same manner as in Example 1 except that 25 g of xylene was used as the hydrocarbon (deformation agent). The obtained resin particles were coagulated, and the average diameter of the aggregate was in a state larger than 200 μm.

Comparative Example 4
Resin particles were obtained in the same manner as in Example 1 except that 5 g of xylene was used instead of the fatty acid ester (plasticizer). Although depressions were formed on the surface of the obtained resin particles, the average number (converted per resin particle) was 0.3.

Comparative Example 5
Resin particles were obtained in the same manner as in Example 1 except that no hydrocarbon (deformation agent) was used. No depression was formed on the surface of the obtained resin particles.

Comparative Example 6
10 hours after the inside of the autoclave reached 80 ° C. (polymerization start temperature), 75 g of pentane (a mixture of n-pentane 80% and isopentane 20%) as a hydrocarbon (deformation agent) was placed in the autoclave over 60 minutes. Except for the addition, the same procedure as in Example 1 was performed to obtain resin particles. No depression was formed on the surface of the obtained resin particles.

Comparative Example 7
Except not using fatty acid ester (plasticizer), it implemented similarly to Example 1 and obtained the resin particle. No depression was formed on the surface of the obtained resin particles.

Comparative Example 8
Resin particles were obtained in the same manner as in Example 1 except that 25 g of glycerin tristearate (Nippon Yushi Co., Ltd. beef tallow extremely hardened oil) was added as a fatty acid ester (plasticizer). The obtained resin particles were coagulated, and the average diameter of the aggregate was in a state larger than 200 μm.

  The average particle diameter, the average number of dents, the density, the diameter of the opening, and the depth of the resin particles obtained in the above Examples and Comparative Examples were measured, and the results are shown in Tables 1 and 2.

  In the measurement of the average particle size in Tables 1 and 2, the particle size distribution is measured by a laser diffraction scattering method using a Microtrac MT-3300EX manufactured by Nikkiso Co., Ltd. as a measuring device, and the cumulative volume with respect to the volume of all particles is 50%. The volume average particle size when At that time, the shape factor of the particles was non-spherical.

  Further, in the measurement of the average number of dents, the density of the dents, and the diameter of the opening of the dents in Tables 1 and 2, the surface of the resin particle was photographed using a scanning electron microscope VE7800 manufactured by Keyence Corporation as a measuring device. The value was measured.

  In addition, in the measurement of the depth of the dents in Tables 1 and 2, resin particles were photographed using a nanoscale hybrid microscope VN8000 manufactured by Keyence Corporation as a measuring device, and the depth of the dents on the surface of the resin particles was cantilever (20 nm) The amount of deflection was measured.

FIG. 1 is a conceptual diagram showing the maximum diameter of the recess opening and the maximum depth of the recess. FIG. 2 is a photomicrograph of the resin particles obtained in Example 1. FIG. 3 is a photomicrograph of the resin particles obtained in Example 3. FIG. 4 is a photomicrograph of the resin particles obtained in Example 8. FIG. 5 is a photomicrograph of the resin particles obtained in Comparative Example 2.

Claims (5)

A dispersion step of obtaining a liquid mixture in which droplets of the vinyl monomer are finely dispersed by stirring the vinyl monomer containing a plasticizer in an aqueous medium, and a vinyl system in the liquid mixture A method for producing vinyl resin particles having an average particle diameter of 1 to 200 μm having depressions on the particle surface, comprising a polymerization step of polymerizing monomers in a reactor,
In the vinyl monomer in the dispersion step, one or more selected from the group of fatty acid ester, liquid paraffin, or olefin as a plasticizer is added in an amount of 0.001 part by weight based on 100 parts by weight of the vinyl monomer. 1-3 parts by weight are added,
In the polymerization step, a hydrocarbon having a solubility parameter of 13 to 17 (MPa) ^1/2 is added to the mixed solution in a state where the polymerization conversion rate of the vinyl monomer is 40 to 98%. A method for producing vinyl resin particles.   The method for producing vinyl resin particles according to claim 1, wherein the amount of the hydrocarbon added is 1 to 30 parts by weight with respect to 100 parts by weight of the vinyl monomer.   The method for producing vinyl-based resin particles according to claim 1 or 2, wherein the hydrocarbon has a boiling point of less than 80 ° C.   4. The vinyl monomer according to claim 1, wherein the vinyl monomer comprises an acrylate ester, or one or more vinyl monomers other than the acrylate ester and the acrylate ester. 5. A method for producing vinyl resin particles.   The method for producing vinyl resin particles according to claim 4, wherein the vinyl monomer comprises methyl methacrylate, styrene, and α-methylstyrene.