JP5214922B2 - Method for producing vinyl-based crosslinked resin particles - Google Patents

Description

  The present invention relates to a method for producing vinyl-based crosslinked resin particles. More specifically, the present invention efficiently uses vinyl-based crosslinked resin particles having an average particle diameter of 1 to 200 μm having depressions on the surface, which are useful in the electrical, electronic, medical, chemical, cosmetic and other industrial fields. It relates to a method of manufacturing.

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 resin fine particles that are generally used have a true spherical shape, it is required to have high functionality such as providing matte and concealing properties for paints, and providing scattering and adhesion properties for cosmetics. In such a case, the above function could not be sufficiently exhibited, and there was room for improvement.
For example, in order to further enhance the function of spherical resin fine particles, Patent Document 1 discloses a method for producing disk-shaped resin fine particles, Patent Document 2 discloses plate-shaped resin fine particles, and Patent Document 3 discloses a method for producing hollow non-spherical resin fine particles. Yes.
In addition, 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, many particles obtained were porous or the shape of the dent was distorted. On the other hand, resin fine particles having a good depression on the surface can be obtained by the method disclosed in Patent Document 4. In the method of Patent Document 4, 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, in this method, since a special fluorinated liquid compound is used, it is necessary to finally separate the resin particles from the fluorinated compound, so that the production and use on an industrial scale is necessary. Due to the difficulty in cost and the absence of a cross-linking agent, it could not be used for applications requiring heat resistance and solvent resistance.

JP-A-63-117040 JP-A-3-234734 Japanese Patent Laid-Open No. 7-157672 JP 2002-88102 A

  Under such circumstances, the present invention can be used for applications requiring heat resistance and solvent resistance, and the vinyl-based crosslinked resin particles having dents on the surface do not require complicated steps and are inexpensive and efficient. It is an object to provide a method for manufacturing well.

  As a result of intensive studies in order to solve the above-mentioned problems, the present inventors prepared an aqueous dispersion in which droplets of a vinyl monomer containing a specific plasticizer in a predetermined ratio are dispersed. The vinyl-based monomer in the aqueous dispersion is polymerized using a specific operation, so that vinyl cross-linked resin particles having a depression on the target surface and an average particle diameter of 1 to 200 μm are obtained. It was found that it can be obtained. The present invention has been completed based on such findings.

That is, the present invention
[1] (a) An aqueous dispersion preparation step of preparing an aqueous dispersion by dispersing droplets of vinyl monomer A in an aqueous medium, and (b) a vinyl-based monomer in the aqueous dispersion. A method for producing vinyl-based crosslinked resin particles having an average particle diameter of 1 to 200 μm having depressions on the particle surface, including a polymerization step of polymerizing the body A,
(1) The droplet of the vinyl monomer A in the step (a) includes a plasticizer that is at least one selected from fatty acid esters and liquid paraffin, and the amount of the plasticizer added is 0.1 to 3 parts by weight with respect to 100 parts by weight of vinyl monomer A,
(2) In the step (b), the solubility parameter is 13.0-15. In a state where the polymerization conversion rate of the vinyl monomer A is 30% or more and less than 50%, or more than 80% and 95% or less. 0 (MPa) ^1/2 of a hydrocarbon compound is added to the polymerization reaction system, and (3) In the step (b), following the operation of (2), the vinyl monomer B and the crosslinking agent are added. Added to the polymerization reaction system, and the addition amount of the vinyl monomer B is 1 to 10 parts by weight with respect to 100 parts by weight of the vinyl monomer A;
A method for producing vinyl-based crosslinked resin particles,
[2] The method for producing vinyl-based crosslinked resin particles according to the above [1], wherein the addition amount of the hydrocarbon compound is 1 to 30 parts by weight with respect to 100 parts by weight of the vinyl-based monomer A.
[3] The method for producing vinyl-based crosslinked resin particles according to [1] or [2], wherein the hydrocarbon compound has a boiling point of less than 60 ° C.
[4] The above [1] to [1], wherein the vinyl monomer A contains a (meth) acrylic ester as a main component, and the vinyl monomer B contains a vinyl aromatic compound as a main component. [3] A method for producing a vinyl-based crosslinked resin particle according to any one of the above,
[5] The method for producing vinyl-based crosslinked resin particles according to any one of the above [1] to [4], wherein the vinyl-based monomer A contains methyl (meth) acrylate and α-methylstyrene,
[6] The method for producing vinyl-based crosslinked resin particles according to any one of [1] to [5] above, wherein the crosslinking agent added in step (b) is divinylbenzene, and step [7] (b). The amount of the cross-linking agent added in the step is 0.5 to 20 parts by weight with respect to 100 parts by weight of the vinyl-based monomer A. Method,
Is to provide.

  According to the production method of the present invention, in the aqueous dispersion preparation step, a vinyl monomer having a specific amount of at least one plasticizer selected from fatty acid esters and liquid paraffin added is dispersed in an aqueous medium. In the polymerization step, after adding a hydrocarbon compound having a specific solubility parameter (SP value), a cross-linking agent and an additional vinyl monomer are added and polymerized to obtain an average particle size of 1 to 200 μm. And the vinyl type crosslinked resin particle which has a hollow in the surface can be obtained easily. In addition, according to the production method of the present invention, vinyl resin particles having depressions on the surface can be obtained without using a special fluorine-based liquid compound such as that employed in Patent Document 4, A complicated process such as a separation operation with a fluorine compound is not required. Accordingly, vinyl-based crosslinked resin particles having depressions on the surface can be produced in large quantities and inexpensively on an industrial scale. Further, according to the present invention, the depression formed on the surface of the resin particle by adjusting the addition time of the hydrocarbon compound, the vinyl monomer and the crosslinking agent having a specific solubility parameter (SP value) in the polymerization step. Since the number and size can be easily adjusted, it is possible to easily provide resin particles that can be adapted to the demands of the electrical, electronic, medical, chemical, cosmetic, and other industrial fields.

The method for producing vinyl-based crosslinked resin particles of the present invention (hereinafter sometimes simply referred to as crosslinked resin particles) includes: (a) Dispersing droplets of vinyl-based monomer A containing a plasticizer in an aqueous medium. An aqueous dispersion preparation step for preparing an aqueous dispersion, and (b) a polymerization step for polymerizing the vinyl monomer A in the aqueous dispersion, and performing the steps (a) and (b). To produce crosslinked resin particles having an average particle diameter of 1 to 200 μm and having depressions on the surface. Here, the crosslinked resin particles refer to resin particles having a degree of swelling of about 0 to 20. The degree of swelling will be described in detail later.
As the method for producing the crosslinked resin particles of the present invention, an emulsion polymerization method, a suspension polymerization method, or the like can be used. Among them, the suspension polymerization method is preferable because it can be easily adjusted to the target average particle diameter.
In this specification, although the said suspension polymerization method is demonstrated as an example, the vinyl-type resin particle which has a hollow in the resin particle surface naturally also in other polymerization methods based on the technique of this invention can be manufactured.

[Step (a)]
Step (a) in the production method of the present invention is an aqueous dispersion preparation step of preparing an aqueous dispersion by dispersing droplets of vinyl monomer A containing a plasticizer in an aqueous medium.
In the aqueous dispersion preparation step, an aqueous medium, a suspending agent, an anionic surfactant, and the like are put into a container equipped with an emulsifying device, and then a vinyl monomer A, a plasticizer, a polymerization initiator, Add chain transfer agent. An aqueous dispersion is prepared by dispersing vinyl-based monomer A containing a plasticizer as fine droplets in an aqueous medium by high-shear stirring in an emulsifier.

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

(Vinyl monomer A)
Examples of the vinyl monomer A used in the present invention include alkyl esters having 1 to 10 carbon atoms of acrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; C 1-10 alkyl esters of methacrylic acid such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate; styrene, α-methylstyrene, o-methylstyrene, m- Methylstyrene, p-methylstyrene, vinyltoluene, p-ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2, 4-dichlorostyrene, pn-hexyl Styrene, p- octyl styrene, styrene sulfonic acid, vinyl aromatic compounds such as sodium styrenesulfonate; acrylonitrile, methacrylonitrile group-containing unsaturated compounds such as nitrites and the like.
These vinyl monomers can be used singly or in combination of two or more according to the intended use of the resulting crosslinked resin particles.

In the present invention, the vinyl monomer A preferably contains a (meth) acrylic acid ester as a main component because the shape of the depression on the surface of the crosslinked resin particles can be easily adjusted. Among (meth) acrylic acid esters, methyl (meth) acrylate is more preferable, and methyl methacrylate is more preferable. In addition, a main component means containing 50-100 weight% of (meth) acrylic acid ester in the vinyl-type monomer A, The said (meth) acrylic acid ester is acrylic acid ester or methacrylic acid ester. Refers to both. Hereinafter, similar expressions are also the same.
From this point of view, the vinyl monomer A particularly preferably contains α-methylstyrene. In this case, the blending amount of α-methylstyrene is preferably more than 0% by weight and 15% by weight or less with respect to the vinyl monomer A.

(Plasticizer)
As the plasticizer, one or more selected from fatty acid esters and liquid paraffin are used. As will be described later, the hydrocarbon compound dissolved in the vinyl monomer is presumed that a depression is formed by phase separation from the polymer as the monomer is polymerized. When the above plasticizer is used, the viscosity of the polymer can be adjusted to an appropriate viscosity range for forming the depression. Among these, fatty acid esters are preferably used from the viewpoint that the density of the recesses and the diameter of the opening can be adjusted relatively easily. The density of the recesses and the diameter of the opening will be described in detail later.
Examples of the fatty acid esters 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, stearin Butyl acid, 2-ethylhexyl stearate, isotridecyl stearate, methyl caprate, methyl myristate, methyl oleate, isobutyl oleate, octyl oleate, lauryl oleate, oleyl oleate, myristyl myristate, stearyl stearate, olein Esters of fatty acids and monohydric alcohols such as 2-ethylhexyl acid, decyl oleate, isobutyl oleate; sorbitan monolaurate, sorbitan mono Lumitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, pentaerythritol monostearate, Examples include esters of fatty acids and polyhydric alcohols such as glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monooleate, glycerin tri-2-ethylhexanoate, cured beef tallow, and cured 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 crosslinked resin particles having a dent density of 0.5 / 100 μm ² 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 depressions, the average carbon number of the liquid paraffin is preferably 10 to 40, and particularly preferably 20 to 35. When the carbon number is too small or too large, it is difficult to form a recess.
The addition amount of the plasticizer (when using a plurality of plasticizers, the total addition amount thereof) is 0.1 to 3 parts by weight per 100 parts by weight of the vinyl monomer A. Within this range, when the depression is formed, the viscosity of the polymer can be adjusted to a viscosity range suitable for the depression formation, so that the depression can be easily formed on the surface of the obtained crosslinked resin particles. . If it is less than 0.1 part by weight, the purpose of forming a depression on the surface of the crosslinked resin particles cannot be achieved. On the other hand, if it exceeds 3 parts by weight, the crosslinked resin particles aggregate. From this viewpoint, the amount of the plasticizer added is preferably 0.3 to 2 parts by weight.
The method for adding the plasticizer is not particularly limited, but a method in which a predetermined amount is added and dissolved in advance in the vinyl monomer A used for the polymerization is preferable.

(Polymerization initiator, chain transfer agent)
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 -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 monomers (total of A and B).
In the present invention, a chain transfer agent such as n-dodecyl mercaptan or α-methylstyrene dimer may be appropriately added to the vinyl monomer A in order to adjust the molecular weight of the resulting crosslinked resin particles.

(Suspending agent)
Examples of the suspending agent added in the present invention include tricalcium phosphate, hydroxyapatite, magnesium pyrophosphate, magnesium phosphate, aluminum hydroxide, ferric hydroxide, titanium hydroxide, magnesium hydroxide, and phosphorus. Examples thereof include particulate water-insoluble inorganic salts such as barium acid, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, talc, kaolin and bentonite. These may be used alone or in combination of two or more, but are preferably tricalcium phosphate, hydroxyapatite, and magnesium pyrophosphate.
The amount of the suspension used is usually preferably 0.05 to 20 parts by weight, more preferably 0.3 to 15 parts by weight, based on 100 parts by weight of the aqueous medium in the aqueous dispersion. . If the amount of the suspending agent used is too small, the vinyl monomer A cannot be suspended and stabilized, and a lump of resin may be generated. Not only is it not preferable, but a problem that the particle size distribution becomes wide is likely to occur.

(Anionic surfactant)
Examples of the anionic surfactant added in the present invention include sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium lauryl sulfate, sodium α-olein sulfonate, sodium dodecylphenyl oxide disulfonate, and the like. These may be used alone or in combination of two or more, preferably an alkali metal salt of an alkyl sulfonic acid having 8 to 20 carbon atoms (preferably a sodium salt), more preferably lauryl. A sulfonic acid alkali metal salt (preferably a 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 hydrogencarbonate, can be added to an aqueous dispersion as needed.

[Step (b)]
Step (b) in the production method of the present invention is a polymerization step in which the vinyl monomer A in the aqueous dispersion prepared in step (a) is polymerized.
In the polymerization step, for example, the aqueous dispersion prepared in the step (a) is put into a reactor equipped with a stirrer, oxygen in the reactor is removed by nitrogen replacement, and then the reactor is stirred. And the vinyl monomer is polymerized at a predetermined temperature for a predetermined time.
The average particle diameter of the crosslinked resin particles obtained by the production method of the present invention is 1 to 200 μm. In order to adjust the average particle size within this range, the dispersion state of the vinyl monomer A may be controlled by the type and amount of an anionic surfactant added to the aqueous dispersion, 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 crosslinked resin particle in this specification means a volume average particle diameter. The volume average particle diameter is obtained as the particle diameter when the crosslinked resin particles are dispersed in water, the particle size distribution is measured by a laser diffraction scattering method, and the cumulative volume with respect to the volume of all particles is 50%. As the measuring device, for example, “Microtrack MT-3300EX” manufactured by Nikkiso Co., Ltd. can be used.

In order to obtain crosslinked resin particles having depressions on the surface, as described in the step (a), the droplets are dispersed using the vinyl monomer A containing a specific plasticizer in a predetermined ratio. In the step (b), the polymerization conversion rate of the vinyl monomer A is 30% or more and less than 50%, or more than 80% and 95% or less. Then, a hydrocarbon compound having a solubility parameter (SP value) of 13.0 to 15.0 (MPa) ^1/2 is added to the reaction system, and then vinyl monomer B and a crosslinking agent are added to the reaction system. The addition amount of the monomer B is required to be 1 to 10 parts by weight with respect to 100 parts by weight of the vinyl monomer A.

(Hydrocarbon compounds)
In the polymerization step, a hydrocarbon compound having a solubility parameter (SP value) of 13.0 to 15.0 (MPa) ^1/2 is used as the hydrocarbon compound (deforming agent) for forming the depression. Examples of the hydrocarbon compound having an SP value of 13.0 to 15.0 (MPa) ^1/2 include butane, pentane, hexane, limonene and the like, and these may be used alone or in combination of two or more. Among them, pentane is particularly preferable from the viewpoint of compatibility with the vinyl monomer.
Hydrocarbon compounds having an SP value of less than 13.0 (MPa) ^1/2 or more than 15.0 (MPa) ^1/2 are unlikely to cause phase separation, which will be described later, and crosslinked resin particles having dents on the surface are obtained. Absent.
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 formula (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 vaporization (J / mol), R: gas constant = 8.314 J / (mol · K), T: absolute temperature (K), d: density (g / cm ³ ), M: molecular weight (g / mol)

The amount of the hydrocarbon compound added to the reaction system is preferably 10 to 30 parts by weight, and more preferably 15 to 25 parts by weight with respect to 100 parts by weight of the vinyl monomer A. When the addition amount of the hydrocarbon compound is too small relative to 100 parts by weight of the vinyl monomer A, phase separation described later is unlikely to occur, and there is a possibility that crosslinked resin particles having depressions on the surface cannot be obtained. If the amount of the hydrocarbon compound added is too large, the suspension system may become unstable and crosslinked resin particles may not be obtained.
Moreover, it is preferable that the boiling point of the hydrocarbon compound used by this invention is less than 60 degreeC. When the boiling point is less than 60 ° C., the hydrocarbon compound can be easily removed from the obtained crosslinked resin particles, and the remaining of the hydrocarbon compound in the crosslinked resin particles can be suppressed as much as possible.
In the polymerization step, the solubility parameter (SP value) is 13.0 to 15 in a state where the polymerization conversion rate of the vinyl monomer A is 30% or more and less than 50% or more than 80% and 95% or less. After adding the 0 (MPa) ^1/2 hydrocarbon compound, the vinyl monomer B and the crosslinking agent are added. When the polymerization conversion is less than 30% or exceeds 95%, when a hydrocarbon compound is added, the phase separation described later hardly occurs and crosslinked resin particles having dents on the surface cannot be obtained. On the other hand, even when the polymerization conversion is 50 to 80% and a hydrocarbon compound is added, the reason is not clear, but only the wrinkles are formed on the surface of the crosslinked resin particles. Not formed.

The reaction conditions of specific temperature and time for adding the hydrocarbon compound to the reaction system and for achieving a polymerization conversion rate of 30% or more and less than 50% or more than 80% and 95% or less are various. Although it cannot be generally determined depending on the blending of components, polymerization conditions, and the like, for example, the temperature is raised to about 80 ° C. at about 0.4 to 0.8 ° C./minute, and then about 115 ° C. to about 0.05 to about 0.00. The temperature can be adjusted by holding at about 15 ° C./min for about 3 to 9 hours with stirring.
In addition, as a method of adding the hydrocarbon compound, the vinyl monomer B, and the crosslinking agent to the reaction system, they may be supplied continuously or intermittently. Specifically, the addition rate is preferably 10 ml / min or less with a metering pump. If the addition rate exceeds 10 ml / min, the suspension system may become unstable and crosslinked resin particles may not be obtained.

In addition, the polymerization conversion rate in this invention can be calculated | required as follows.
About 5 g of the soot-like polymer is taken out from the reactor before the hydrocarbon compound is added 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”.
It is then dissolved in 5-6 ml of chloroform per gram of polymer (100% purity). 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 longer. 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)

  In the present invention, the mechanism by which vinyl-based crosslinked resin particles having depressions on the surface are obtained is not clear, but is presumed as follows. It is inferred that the hydrocarbon compound initially dissolved in the monomer phase undergoes phase separation from the polymer due to the change in solubility as the monomer polymerization proceeds, 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 control the state of phase separation by using a transfer agent, or changing the type and amount of the polymerization initiator or the polymerization temperature condition.

(Vinyl monomer B)
In the present invention, cross-linked resin particles are produced by adding a cross-linking agent. However, as the cross-linking of the polymer proceeds, the solubility of the hydrocarbon compound in the polymer changes, and in a state where a depression is formed. Disappear. Therefore, by adding a specific amount of vinyl monomer B in the polymerization step, the solubility of the hydrocarbon compound in the polymer can be adjusted to a range suitable for the formation of the depression.
Examples of the vinyl monomer B include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, vinyl toluene, p-ethyl styrene, 2,4-dimethyl styrene, p-methoxy styrene. P-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, pn-hexylstyrene, p-octylstyrene, styrenesulfonic acid, sodium styrenesulfonate, etc. Vinyl aromatic compounds; alkyl esters having 1 to 10 carbon atoms of acrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, Propyl methacrylate, butyl methacrylate, Alkyl esters having a carbon number of 1 to 10 methacrylic acid such as methacrylic acid 2-ethylhexyl; acrylonitrile, methacrylonitrile group-containing unsaturated compounds such as nitrites and the like. These may be used individually by 1 type, and may be used in combination of 2 or more types.
In the present invention, since the vinyl monomer B is easy to adjust the solubility of the hydrocarbon compound as described above, it is preferable that the vinyl monomer B is mainly composed of a vinyl aromatic compound, and styrene is mainly used. More preferably, it is a component. In this case, the main component means that 50 to 100% by weight of the vinyl aromatic compound is contained in the vinyl monomer B.
When a vinyl monomer other than the vinyl aromatic compound is used in combination, the vinyl monomer is preferably a (meth) acrylic acid ester and more preferably methyl methacrylate.
The amount of the vinyl monomer B to be added is 1 to 10 parts by weight and 3 to 8 parts by weight with respect to 100 parts by weight of the vinyl monomer A used in the step (a). preferable. When the addition amount of the vinyl monomer B is less than 1 part by weight or more than 10 parts by weight, crosslinked resin particles having depressions on the surface cannot be obtained.

(Crosslinking agent)
As the crosslinking agent, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, (meth) acrylic monomers such as pentaerythritol tetra (meth) acrylate, divinylbenzene, Crosslinkable monomers such as aromatic divinyl compounds such as divinylnaphthalene can be used. These crosslinking agents may be used alone or in combination of two or more. Of these, divinylbenzene is particularly preferred from the viewpoint of compatibility with vinyl monomers.
The amount of the crosslinking agent to be added is preferably 0.5 to 20 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the vinyl monomer A used in the step (a). preferable. When the amount of the crosslinking agent is within the above range, the suspension resin is less likely to be unstable, and crosslinked resin particles having depressions on the surface with good solvent resistance can be obtained.
Further, the vinyl monomer B and the cross-linking agent are added to a mixed solution containing water and an emulsifier, and stirred in an emulsifying apparatus (for example, at a rotation speed of 10,000 rpm for 5 minutes or more) to emulsify with water. It is preferable to add as. About the water and emulsifier used when making it into an emulsion, when the sum total of the vinyl-type monomer B and the crosslinking agent to add is 100 weight part, about 10-100 weight part water and 0.01-1 An anionic surfactant of about part by weight is preferred.

In the present invention, the vinyl monomer B and the crosslinking agent are added after the hydrocarbon compound is added. When the vinyl monomer B and the crosslinking agent are added before the hydrocarbon compound, a crosslinking reaction occurs before the hydrocarbon compound dissolves in the polymer. Therefore, the solubility of the hydrocarbon compound in the polymer, and the polymer Since the viscosity cannot be adjusted to an appropriate range for forming the depression, the depression is not formed. Further, when the vinyl monomer B and the crosslinking agent are added simultaneously with the hydrocarbon compound, the crosslinked resin particles are condensed.
In order to easily form the dent, the addition of the vinyl monomer B and the cross-linking agent progressed by 2 to 20% after the addition of the hydrocarbon compound, compared to the polymerization conversion at the time of adding the hydrocarbon compound. It is preferable to carry out at the time (however, the polymerization conversion rate when the vinyl monomer B and the crosslinking agent are added is less than 100%), and more preferably at the time when it has progressed 3 to 15% (however, The polymerization conversion rate when adding the vinyl monomer B and the cross-linking agent is less than 100%.) It is more preferable to carry out at the time when it proceeds 4 to 10% (however, the vinyl monomer B and The polymerization conversion rate when adding the cross-linking agent is less than 100%).

The crosslinked resin particles thus formed are taken out from the reaction-finished liquid by a known solid-liquid separation means such as filtration or centrifugation, and after removing the suspending agent attached to the surface, washing and drying treatment are performed. Vinyl-based crosslinked resin particles having a depression on the target surface can be obtained.
Next, the vinyl type | system | group crosslinked resin particle obtained by the method of this invention is demonstrated.
[Vinyl cross-linked resin particles]
As shown in the conceptual diagram of FIG. 1, the vinyl-based crosslinked resin particles obtained by the method of the present invention have depressions on the surface thereof. The shape of the dent is that the shape of the opening of the dent is circular or elliptical, a dish shape with a shallow dent depth, or a bowl shape with a deep dent depth, that is, a shape that is recessed in a substantially hemispherical shape. It is like a crater. One or more, preferably a plurality of such depressions are formed on the surface of the crosslinked resin particles with respect to one crosslinked resin particle.
The average diameter of the openings of the depressions of the crosslinked resin particles formed according to the present invention is generally 0.1 to 15 μm, preferably 0.8 to 10 μm, although it depends on the average particle diameter of the resin particles and the use thereof. And 1 to 20% of the average particle size. Density of the depression of the crosslinked resin particles are generally 0.3 to 200 pieces / 100 [mu] m ^2, depending on the application of the resin particles is preferably 0.5 to 50 pieces / 100 [mu] m ^2.
Moreover, although the average depth of a hollow is based also on the average particle diameter of crosslinked resin particle, it is about 0.02-5 micrometers normally, Preferably it is 0.05-3 micrometers, and is 0.1-0.1 with respect to an average particle diameter. It is 10% deep.

The average diameter of the opening of the depression is a value calculated as an arithmetic average value of the values obtained by measuring the diameter of the opening at 20 arbitrary depressions on the surface of the crosslinked resin particles. Specifically, the surface of the vinyl-based crosslinked resin particles is enlarged and photographed with a scanning electron microscope, the maximum diameter is measured for any 20 recessed openings, and the arithmetic average of the measured 20 maximum diameters is measured. It is a value calculated as a value. In addition, the measurement of the maximum diameter of a hollow opening part may measure 20 places about one particle | grain, and may measure 20 places over several particle | grains. However, when 20 depressions do not exist in one particle, 20 spots are measured over a plurality of particles.
The density of the depressions was measured by enlarging the surface of the crosslinked resin particles with a scanning electron microscope and taking a photograph, and measuring the number of depressions on the surface of each crosslinked resin particle for 20 arbitrary crosslinked resin particles. Based on the diameter of the crosslinked resin particles, the surface area of the resin particles is calculated, the number of depressions per 100 μm ² surface area of each crosslinked resin particle is calculated, and the calculated depressions per 100 μm ² surface area of the 20 crosslinked resin particles are calculated. It is a value calculated as an arithmetic average value of numbers. In addition, even when only a part of the depression can be observed, it is measured as one depression. If the entire cross-linked resin particle does not fit in the photograph, the magnification is changed so that the whole fits in the photomicrograph.
The average depth of the depression is specifically a value measured as follows. Vinyl-based crosslinked resin particles are photographed using a nanoscale hybrid microscope, and the depth of the depression on the surface of the crosslinked resin particles is measured based on the amount of deflection of the cantilever at any 20 locations. The arithmetic average value of the measured values at 20 locations is defined as the average depth of the depression.

Next, the degree of swelling of the crosslinked resin particles obtained by the method of the present invention will be described in detail.
The degree of swelling of the crosslinked resin fine particles means that 1 g of crosslinked resin particles is precisely weighed in a graduated cylinder, tapped several times, and then the crosslinked portion of the resin particles is dissolved and not swollen at room temperature such as toluene, and the uncrosslinked portion is dissolved. The solvent which can be swollen is gently transferred along the wall surface and put to 50 ml. Then, let stand at 25 ° C. for 24 hours, read the height of the swollen gel in ml,
Swelling degree [−] = (reading value [ml] × 0.5 [g / ml]) / sampled amount [g]. In the above formula, 0.5 [g / ml] is the bulk density of the crosslinked resin particles.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the various characteristics in each example were calculated | required according to the method shown below.
(1) Volume average particle diameter (d50): Measurement of 50% particle diameter of crosslinked resin particles Crosslinked resin particles are dispersed in water, and laser diffraction scattering method ("Microtrack MT-3300EX" (trade name) manufactured by Nikkiso Co., Ltd.) ) To measure the particle size distribution, and the particle size when the cumulative volume with respect to the volume of all particles was 50% was determined as the 50% particle size. The shape factor of the particles was non-spherical.
(2) Dispersity (d90 / d10): Measurement of ratio of 90% particle diameter to 10% particle diameter of crosslinked resin particles Crosslinked resin particles were dispersed in water, and laser diffraction scattering method ("Microtrack MT" manufactured by Nikkiso Co., Ltd. -3300EX "(trade name)), the particle size when the cumulative volume with respect to the volume of all particles becomes 10% and 90% is set to 10% particle size and 90% particle size, respectively. The value obtained by dividing the diameter by the 10% particle diameter was used. The shape factor of the particles was non-spherical.

(3) Density density of crosslinked resin particles, average diameter of openings, average depth For measurement of the average diameter of depressions on the surface of particles and the density of depressions, a scanning electron microscope “manufactured by Keyence Corporation” The surface of the crosslinked resin particles was photographed using “VE7800” (trade name).
As described above, the average diameter of the openings of the depressions is a value calculated as an arithmetic average value of the values obtained by measuring the diameter of the openings at 20 arbitrary depressions on the surface of the crosslinked resin particles. . Specifically, the surface of the vinyl-based crosslinked resin particles was magnified 2000 times with a scanning electron microscope and photographed, the maximum diameter was measured for any 20 recessed openings, and the 20 maximum diameters measured. It was calculated as an arithmetic average value of
As described above, the density of the depressions means that the surface of the crosslinked resin particles is magnified 2000 times with a scanning electron microscope and photographed, and the number of depressions on each crosslinked resin particle surface for 20 arbitrary resin particles. And calculating the surface area of the resin particles based on the measured resin particle diameter, etc., calculating the number of depressions per 100 μm ² surface area of each crosslinked resin particle, and calculating the calculated 20 crosslinked resin particles. It was calculated as the arithmetic average value of the number of depressions per surface area of 100 μm ² .

(4) Average Depth of Depression Vinyl-based crosslinked resin particles were photographed at a magnification of 1250 times using a nanoscale hybrid microscope (VN8000 (trade name) manufactured by Keyence Corporation). The depth of the depression on the particle surface was measured by the amount of deflection of the cantilever. The arithmetic average value of the measured values at 20 locations was defined as the average depth of the depressions.
(5) Swelling degree of crosslinked resin particles 1 g of resin particles are precisely weighed in a measuring cylinder, tapped several times, and toluene is gently transferred along the wall surface to 50 ml. Then, let stand at 25 ° C. for 24 hours, read the height of the swollen gel in ml,
The degree of swelling [−] = (reading value [ml] × 0.5 [g / ml]) / sampled amount [g] was calculated.
(6) Measurement of total light transmittance and haze of diffusive film A 50 mm x 50 mm sample piece was cut out from the light diffusing film, and the total light transmittance was measured with a haze meter ("NDH5000" (trade name) manufactured by Nippon Denshoku). And measured haze.

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 a magnesium pyrophosphate slurry as a suspending agent.
Next, to this reaction product-containing slurry, 5 g of a 10% by weight aqueous solution of sodium lauryl sulfonate and 375 g of methyl methacrylate as a vinyl monomer A, 90 g of styrene and 35 g of α-methylstyrene in advance as a polymerization initiator Benzoyl (Nippa Oil & Fats Co., Ltd. “Niper BW” (trade name), water diluted powder product) 2.5 g, t-butyl peroxy 2-ethylhexyl carbonate 0.67 g, α-methylstyrene dimer (Nippon Yushi) as chain transfer agent After adding 1 g of “NOFMER MSD” (trade name) manufactured by KK and 5 g of glycerin tristearate (beef fat hardened by Nippon Oil & Fats Co., Ltd.) as a plasticizer, the mixture was homogenized (M Technique Co., Ltd.). Product), and the vinyl monomer A is finely separated in water. Scattered.

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 6.5 hours, maintained at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours. Two hours and 30 minutes after reaching 80 ° C. (polymerization start temperature), 60 g of pentane (a mixture of n-pentane 80% and isopentane 20%) was added as a hydrocarbon compound (deforming agent) for about 10 minutes and added to the autoclave. Next, 3 hours after reaching 80 ° C. (polymerization start temperature), the previously prepared emulsion was added for about 20 minutes and added to the autoclave. This emulsion is obtained by adding 30 g of styrene as a vinyl monomer B and 20 g of divinylbenzene as a cross-linking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate, and adding it to a homogenizer (manufactured by M Technique). The vinyl monomer B is finely dispersed in water by stirring for 5 minutes at a rotational speed of 10,000 rpm.
After cooling, the contents were taken out, 25 ml of nitric acid (67.5% by weight) was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent adhering to the surface of the crosslinked resin particles. Then, it spin-dry | dehydrated and wash | cleaned with the centrifuge, the water | moisture content was removed with the vacuum dryer, and the crosslinked resin particle was obtained.
In addition, the microscope picture of the crosslinked resin particle obtained in Example 1 is shown in FIG.

Example 2
75 g of pentane (a mixture of 80% n-pentane and 20% isopentane) is used as a hydrocarbon compound (deforming agent), and is added over 20 minutes 5 hours and 30 minutes after reaching 80 ° C. (polymerization start temperature). 6 hours after reaching 80 ° C. (polymerization start temperature), the emulsion prepared in advance was applied for about 20 minutes, and the mixture was added to the autoclave in the same manner as in Example 1 to obtain crosslinked resin particles. Obtained. This emulsion was prepared by adding 30 g of styrene as a vinyl monomer B and 20 g of divinylbenzene as a cross-linking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. ), The vinyl monomer B is finely dispersed in water by stirring at 10000 rpm for 5 minutes.
In addition, the microscope picture of the crosslinked resin particle obtained in Example 2 is shown in FIG.

Example 3
100 g of pentane (a mixture of 80% n-pentane and 20% isopentane) is used as the hydrocarbon compound (deforming agent), added over 20 minutes after reaching 80 ° C. (polymerization start temperature), and then 6 hours after reaching 80 ° C. (polymerization start temperature), the emulsion prepared in advance was applied for about 20 minutes, and the mixture was added to the autoclave in the same manner as in Example 1 to obtain crosslinked resin particles. Obtained. The emulsion was prepared by adding 12 g of methyl methacrylate as vinyl monomer B, 18 g of styrene and 20 g as a crosslinking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. (Manufactured by Technic Co., Ltd.), and the vinyl monomer B is finely dispersed in water by stirring at 10,000 rpm for 5 minutes.
Example 4
A crosslinked resin was prepared in the same manner as in Example 1 except that 5 g of glycerin monostearate was used as the plasticizer and 125 g of butane (mixture of 70% n-butane and 30% isobutane) was used as the hydrocarbon compound (deforming agent). Particles were obtained.

Example 5
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 a magnesium pyrophosphate slurry as a suspending agent.
Next, to this reaction product-containing slurry, 5 g of a 10% by weight aqueous solution of sodium lauryl sulfonate, 465 g of methyl methacrylate as vinyl monomer A in advance and 35 g of α-methylstyrene were added to benzoyl peroxide as a polymerization initiator (Japan). “Nyper BW” (trade name) manufactured by Yushi Co., Ltd., 2.5 g of water-diluted powder product, 0.67 g of t-butylperoxy 2-ethylhexyl carbonate, α-methylstyrene dimer (manufactured by Nippon Yushi Co., Ltd. “ 1 g of NOFMER MSD "(trade name)) and a solution in which 10 g of 2-ethylhexanoic acid triglyceride (" EXEPEARL TGO "(trade name) manufactured by Kao Corporation) was dissolved as a plasticizer were added. (Made by Technic Co., Ltd.) and stirring for 10 minutes at a rotation speed of 10,000 rpm, It was allowed to 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 6.5 hours, maintained at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours. Five hours and 30 minutes after reaching 80 ° C. (polymerization start temperature), 75 g of decane was added as a hydrocarbon compound (deforming agent) for about 10 minutes and added to the autoclave. Next, 6 hours after reaching 80 ° C. (polymerization start temperature), the previously prepared emulsion was added for about 20 minutes and added to the autoclave. This emulsion was prepared by adding 10 g of methyl methacrylate as vinyl monomer B, 20 g of styrene and 30 g of divinylbenzene as a crosslinking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. (Manufactured by Technic Co., Ltd.), and the vinyl monomer B is finely dispersed in water by stirring at 10,000 rpm for 5 minutes.
After cooling, the contents were taken out, 25 ml of nitric acid (67.5% by weight) was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent adhering to the surface of the crosslinked resin particles. Then, it spin-dry | dehydrated and wash | cleaned with the centrifuge, the water | moisture content was removed with the vacuum dryer, and the crosslinked resin particle was obtained.

Example 6
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 a magnesium pyrophosphate slurry as a suspending agent.
Next, to this reaction product-containing slurry, 5 g of a 10% by weight aqueous solution of sodium lauryl sulfonate and 300 g of methyl methacrylate as a vinyl monomer A, 165 g of styrene, and 35 g of α-methylstyrene were previously oxidized as a polymerization initiator. Benzoyl (Nippa Oil & Fats Co., Ltd. “Niper BW” (trade name), water diluted powder product) 2.5 g, t-butyl peroxy 2-ethylhexyl carbonate 0.67 g, α-methylstyrene dimer (Nippon Yushi) as chain transfer agent After adding 1 g of “NOFMER MSD” (trade name) manufactured by the company and 12.5 g of sorbitan monooleate (“Emazole O10 (F)” (trade name) manufactured by Kao Corporation) as a plasticizer, The mixed solution is stirred with a homogenizer (manufactured by M Technique Co., Ltd.) for 10 minutes at a rotation speed of 10,000 rpm, Nyl monomer A 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 6.5 hours, maintained at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours. Five hours and 30 minutes after reaching 80 ° C. (polymerization start temperature), 75 g of pentane (a mixture of 80% n-pentane and 20% isopentane) was added as a hydrocarbon compound (deforming agent) for about 10 minutes and added to the autoclave. Next, 6 hours after reaching 80 ° C. (polymerization start temperature), the previously prepared emulsion was added for about 20 minutes and added to the autoclave. This emulsion was prepared by adding 10 g of methyl methacrylate as vinyl monomer B, 20 g of styrene and 20 g of divinylbenzene as a crosslinking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. (Manufactured by Technic Co., Ltd.), and the vinyl monomer B is finely dispersed in water by stirring at 10,000 rpm for 5 minutes.
After cooling, the contents were taken out, 25 ml of nitric acid (67.5% by weight) was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent adhering to the surface of the crosslinked resin particles. Then, it spin-dry | dehydrated and wash | cleaned with the centrifuge, the water | moisture content was removed with the vacuum dryer, and the crosslinked resin particle was obtained.

Example 7
1150 g of deionized water was placed in a 3 L reactor (autoclave) equipped with a stirring blade, 18.6 g of sodium pyrophosphate was further added and dissolved, and then 43.1 g of powdered magnesium nitrate hexahydrate was added. In addition, the mixture was stirred at room temperature for 30 minutes to synthesize a magnesium pyrophosphate slurry as a suspending agent.
Next, this reaction product-containing slurry was polymerized into 5.8 g of a 10% by weight aqueous solution of sodium lauryl sulfonate and 262.5 g of methyl methacrylate, 63 g of styrene and 24.5 g of α-methylstyrene as the vinyl monomer A in advance. 1.75 g of benzoyl peroxide as an initiator (“NIPPER BW” (trade name) manufactured by NOF Corporation, water-diluted powder product), 0.47 g of t-butylperoxy 2-ethylhexyl carbonate, α- as a chain transfer agent 2. 0.7 g of methylstyrene dimer (“NOFMER MSD” (trade name) manufactured by NOF Corporation), liquid paraffin as a plasticizer (27 carbon atoms, “Moresco White P150” (trade name) manufactured by Matsumura Oil Research Co., Ltd.) After adding 5 g of the dissolved solution, the mixed solution was rotated at 10,000 rpm with a homogenizer (manufactured by M Technique). For 10 minutes to disperse the vinyl monomer A finely in water.

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 6.5 hours, maintained at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours. 5 hours and 30 minutes after reaching 80 ° C. (polymerization start temperature), 52.5 g of pentane (a mixture of n-pentane 80% and isopentane 20%) is added as a hydrocarbon compound (deforming agent) for about 10 minutes and added to the autoclave. did. Next, 6 hours after reaching 80 ° C. (polymerization start temperature), the previously prepared emulsion was added for about 20 minutes and added to the autoclave. This emulsion is obtained by adding 21 g of styrene as a vinyl monomer B and 28 g of divinylbenzene as a cross-linking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate, and adding it to a homogenizer (manufactured by M Technique). The vinyl monomer B is finely dispersed in water by stirring for 5 minutes at a rotational speed of 10,000 rpm.
After cooling, the contents were taken out, 25 ml of nitric acid (67.5% by weight) was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent adhering to the surface of the crosslinked resin particles. Then, it spin-dry | dehydrated and wash | cleaned with the centrifuge, the water | moisture content was removed with the vacuum dryer, and the crosslinked resin particle was obtained.

Example 8
In a 3 L reactor (autoclave) equipped with a stirring blade, 1070 g of deionized water was added, and 17.3 g of sodium pyrophosphate was added and dissolved, and then 40.1 g of powdered magnesium nitrate hexahydrate was added. In addition, the mixture was stirred at room temperature for 30 minutes to synthesize a magnesium pyrophosphate slurry as a suspending agent.
Next, 5.4 g of a 10% by weight aqueous solution of sodium lauryl sulfonate and 322.5 g of methyl methacrylate as a vinyl monomer A, 77.4 g of styrene, and 30.1 g of α-methylstyrene were added to the reaction product-containing slurry. Benzoyl peroxide as a polymerization initiator (“Nyper BW” (trade name) manufactured by NOF Corporation, water diluted powder product) 2.2 g, 0.6 g of t-butylperoxy 2-ethylhexyl carbonate, as a chain transfer agent α-methylstyrene dimer (“NOFMER MSD” (trade name) manufactured by NOF Corporation), liquid paraffin (30 carbon atoms, “Moresco White P260” (trade name) manufactured by Matsumura Oil Research Co., Ltd.) After adding a solution in which 4.3 g was dissolved, the mixed solution was rotated at 10,000 rpm with a homogenizer (manufactured by M Technique). Was stirred for 10 minutes to finely disperse the vinyl monomer A in the water.

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 6.5 hours, maintained at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours. Five hours and 30 minutes after reaching 80 ° C. (polymerization start temperature), 64.5 g of pentane (a mixture of n-pentane 80% and isopentane 20%) is added as a hydrocarbon compound (deforming agent) for about 10 minutes and added to the autoclave. did. Next, 6 hours after reaching 80 ° C. (polymerization start temperature), the previously prepared emulsion was added for about 20 minutes and added to the autoclave. This emulsion was prepared by adding 25.8 g of styrene as a vinyl monomer B and 8.6 g of divinylbenzene as a crosslinking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. The vinyl monomer B is finely dispersed in water by stirring at 10000 rpm for 5 minutes.
After cooling, the contents were taken out, 25 ml of nitric acid (67.5% by weight) was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent adhering to the surface of the crosslinked resin particles. Then, it spin-dry | dehydrated and wash | cleaned with the centrifuge, the water | moisture content was removed with the vacuum dryer, and the crosslinked resin particle was obtained.

Example 9
A hydrocarbon compound (deformation agent) was added over 10 minutes after 2 hours 15 minutes at 80 ° C. (polymerization start temperature), and the emulsion emulsified with water was reached at 80 ° C. (polymerization start temperature) 2 hours 30 hours. This was carried out in the same manner as in Example 2 except that the addition was carried out over 20 minutes, to obtain crosslinked resin particles.
Example 10
A hydrocarbon compound (amorphizing agent) was added over 10 minutes after reaching 80 ° C. (polymerization start temperature) over 10 minutes, and the emulsion emulsified with water was added after 3 hours 30 minutes when reaching 80 ° C. (polymerization start temperature). The same procedure as in Example 2 was conducted except that the addition was performed over 20 minutes to obtain crosslinked resin particles.

Example 11
A hydrocarbon compound (deformation agent) was added over 10 minutes after reaching 80 ° C. (polymerization start temperature) over 10 minutes, and the emulsion emulsified with water was reached after 6 hours 30 minutes reaching 80 ° C. (polymerization start temperature). The same procedure as in Example 2 was conducted except that the addition was performed over 20 minutes to obtain crosslinked resin particles.
Example 12
After adding a hydrocarbon compound (deformation agent), 6 g of styrene as vinyl monomer B and 20 g of divinylbenzene as a crosslinking agent are added to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate, and a homogenizer. (M Technique Co., Ltd.) and Example 2 except that the emulsion in which the vinyl monomer B was finely dispersed in water was added to the autoclave with stirring at 10000 rpm for 5 minutes. In the same manner, crosslinked resin particles were obtained.

Example 13
After adding a hydrocarbon compound (deformation agent), 47.5 g of styrene as vinyl monomer B and 20 g of divinylbenzene as a crosslinking agent are added to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. In Example, except that the homogenizer (manufactured by M Technique Co., Ltd.) was stirred for 5 minutes at a rotational speed of 10,000 rpm, and an emulsion in which the vinyl monomer B was finely dispersed in water was added to the autoclave. In the same manner as in No. 2, crosslinked resin particles were obtained.
Example 14
A hydrocarbon compound (deformation agent) was added over 10 minutes after reaching 80 ° C. (polymerization start temperature) for 10 minutes, and the emulsion emulsified with water was added 5 hours after reaching 80 ° C. (polymerization start temperature). The same procedure as in Example 2 was conducted except that the addition was performed over 20 minutes to obtain crosslinked resin particles.

Comparative Example 1
The same procedure as in Example 2 was carried out except that the hydrocarbon compound (deforming agent) was not added, to obtain crosslinked resin particles. No depression was formed on the surface of the obtained crosslinked resin particles.
In addition, the microscope picture of the resin particle obtained by the comparative example 1 is shown in FIG.
Comparative Example 2
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 a magnesium pyrophosphate slurry as a suspending agent.
Next, to this reaction product-containing slurry, 5 g of a 10% by weight aqueous solution of sodium lauryl sulfonate and 300 g of methyl methacrylate as a vinyl monomer A, 165 g of styrene, and 35 g of α-methylstyrene were previously oxidized as a polymerization initiator. Benzoyl (Nippa Oil & Fats Co., Ltd. “Niper BW” (trade name), water diluted powder product) 2.5 g, t-butyl peroxy 2-ethylhexyl carbonate 0.67 g, α-methylstyrene dimer (Nippon Yushi) as chain transfer agent After adding 1 g of “NOFMER MSD” (trade name) manufactured by KK and 5 g of glycerin tristearate (beef fat hardened by Nippon Oil & Fats Co., Ltd.) as a plasticizer, the mixture was homogenized (M Technique Co., Ltd.). Product) and stirring at a rotational speed of 10,000 rpm for 10 minutes to make the vinyl monomer A fine in water. Dispersed.

Next, 75 g of pentane (a mixture of 80% n-pentane and 20% isopentane) as a hydrocarbon compound (a deforming agent) and an emulsion prepared in advance were added into the autoclave. This emulsion was prepared by adding 10 g of methyl methacrylate as vinyl monomer B, 20 g of styrene and 20 g of divinylbenzene as a crosslinking agent to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. (Manufactured by Technic Co., Ltd.), and the vinyl monomer B is finely dispersed in water by stirring at 10,000 rpm for 5 minutes.
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 6.5 hours, maintained at 115 ° C. for 5 hours, and then cooled to 30 ° C. over about 6 hours.
After cooling, the contents were taken out, 25 ml of nitric acid (67.5% by weight) was added, and the mixture was stirred for 15 minutes to dissolve the suspending agent adhering to the surface of the crosslinked resin particles. Then, it spin-dry | dehydrated and wash | cleaned with the centrifuge, the water | moisture content was removed with the vacuum dryer, and the crosslinked resin particle was obtained.

Comparative Example 3
A hydrocarbon compound (amorphizing agent) was added over 10 minutes after reaching 80 ° C. (polymerization start temperature) over 10 minutes, and an emulsion emulsified with water was added after 2 hours 30 minutes after reaching 80 ° C. (polymerization start temperature). The same procedure as in Example 2 was conducted except that the addition was performed over 20 minutes to obtain crosslinked resin particles. The obtained crosslinked resin particles were agglomerated and were larger than 200 μm.
Comparative Example 4
A hydrocarbon compound (amorphizing agent) was added over 10 minutes after reaching 80 ° C. (polymerization start temperature) for 10 minutes, and the emulsion emulsified with water was added 4 hours after reaching 80 ° C. (polymerization start temperature). The same procedure as in Example 2 was conducted except that the addition was performed over 20 minutes to obtain crosslinked resin particles. No depression was formed on the surface of the obtained crosslinked resin particles.

Comparative Example 5
A hydrocarbon compound (deformation agent) was added over 10 minutes after reaching 80 ° C. (polymerization start temperature) for 10 minutes, and the emulsion emulsified with water was added after 5 hours 30 minutes at 80 ° C. (polymerization start temperature). The same procedure as in Example 2 was conducted except that the addition was performed over 20 minutes to obtain crosslinked resin particles. No depression was formed on the surface of the obtained crosslinked resin particles.
Comparative Example 6
A hydrocarbon compound (deformation agent) was added over 10 minutes after reaching 80 ° C. (polymerization start temperature) for 10 minutes, and the emulsion emulsified with water was 7 hours after reaching 80 ° C. (polymerization start temperature). The same procedure as in Example 2 was conducted except that the addition was performed over 20 minutes to obtain crosslinked resin particles. No depression was formed on the surface of the obtained crosslinked resin particles.

Comparative Example 7
A crosslinked resin particle was obtained in the same manner as in Example 2 except that 75 g of neopentane was used as the hydrocarbon compound (deforming agent). No depression was formed on the surface of the obtained crosslinked resin particles.
Comparative Example 8
A crosslinked resin particle was obtained in the same manner as in Example 2 except that 75 g of heptane was used as the hydrocarbon compound (deforming agent). No depression was formed on the surface of the obtained crosslinked resin particles.
Comparative Example 9
A crosslinked resin particle was obtained in the same manner as in Example 2 except that 75 g of xylene was used as the hydrocarbon compound (deforming agent). The obtained crosslinked resin particles were agglomerated and were larger than 200 μm.

Comparative Example 10
The same procedure as in Example 2 was carried out except that xylene was used as a plasticizer to obtain crosslinked resin particles. The obtained crosslinked resin particles were agglomerated and were larger than 200 μm.
Comparative Example 11
Except not using a plasticizer, it implemented similarly to Example 2 and obtained the crosslinked resin particle. No depression was formed on the surface of the obtained crosslinked resin particles.
Comparative Example 12
Resin particles were obtained in the same manner as in Example 2 except that 25 g of glycerin tristearate (Nippon Yushi Co., Ltd. beef tallow extremely hardened oil) was added as a plasticizer. The obtained crosslinked resin particles were agglomerated and were larger than 200 μm.
Comparative Example 13
Resin particles were obtained in the same manner as in Example 2 except that divinylbenzene was not added as a crosslinking agent.

Comparative Example 14
After adding a hydrocarbon compound (deformation agent), 20 g of divinylbenzene as a cross-linking agent was added to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate, and the number of rotations was increased with a homogenizer (manufactured by M Technique). Stirring was performed at 10,000 rpm for 5 minutes, and the same procedure as in Example 2 was performed except that an emulsion in which a crosslinking agent was finely dispersed in water was added to the autoclave, to obtain crosslinked resin particles. No depression was formed on the surface of the obtained crosslinked resin particles.
Comparative Example 15
An emulsion emulsified with water was added over 20 minutes after reaching 80 ° C. (polymerization start temperature) for 20 minutes, and a hydrocarbon compound (deformer) was added 10 hours after reaching 80 ° C. (polymerization start temperature). Except that it was added over a period of time, the same procedure as in Example 2 was performed to obtain crosslinked resin particles. The obtained crosslinked resin particles were agglomerated and were larger than 200 μm.

Comparative Example 16
Carried out in the same manner as in Example 2 except that an emulsion emulsified with a hydrocarbon compound (a deforming agent) and water was added over 20 minutes after reaching 80 ° C. (polymerization start temperature) for 5 hours and 30 minutes, Crosslinked resin particles were obtained. The obtained crosslinked resin particles were agglomerated and were larger than 200 μm.
Comparative Example 17
After adding a hydrocarbon compound (deformation agent), 55 g of styrene as vinyl-based monomer B and 20 g of divinylbenzene as a cross-linking agent are added to a dispersion of 30 g of pure water and 1 g of a 10% by weight aqueous solution of sodium lauryl sulfonate. (M Technique Co., Ltd.) and Example 2 except that the emulsion in which the vinyl monomer B was finely dispersed in water was added to the autoclave with stirring at 10000 rpm for 5 minutes. In the same manner, crosslinked resin particles were obtained. No depression was formed on the surface of the obtained crosslinked resin particles.
The polymerization conditions of the crosslinked resin particles obtained in Examples 1 to 14 and Comparative Examples 1 to 17, the density of the depressions, the average diameter of the openings, the average depth of the depressions, d50, the degree of dispersion (d90 / d10), The degree of swelling is shown in Tables 1 to 4.

As is clear from Tables 1 to 4, the crosslinked resin particles obtained in Examples 1 to 14 all have depressions on the surface, good solvent resistance, no condensation, and average particle diameter. Is in the range of 7 to 23 μm. On the other hand, the crosslinked resin particles obtained in Comparative Examples 1 to 12 and Comparative Examples 14, 16, and 17 have no dents, and Comparative Examples 2, 3, 9, 10, 12, and 16 among these have no condensation. Has occurred.
The cross-linked resin particles obtained in Comparative Example 13 have poor solvent resistance because no cross-linking agent is used, and the cross-linked resin particles obtained in Comparative Example 15 have depressions but are condensed.

Example 15
A predetermined amount (0.2 g, 0.5 g, 1 g) of the crosslinked resin fine particles obtained in Example 1 is weighed. Each of the measured cross-linked resin particles and 10 g of binder resin (Toyobo Co., Ltd. “Vylonal MD-1200” (trade name)) is stirred and mixed for 5 minutes, and a PET film (manufactured by Toray Industries Inc.) with a small coating apparatus It was applied to “Luminer 100T6” (trade name) with a thickness of 100 μm. Then, it heated at 80 degreeC with the dryer for 1 hour, and produced the light-diffusion film.
Example 16
A light diffusion film was produced in the same manner as in Example 15 except that the crosslinked resin particles of Example 2 were used.
Example 17
A light diffusion film was produced in the same manner as in Example 15 except that the crosslinked resin particles of Example 3 were used.
Comparative Example 18
A light diffusion film was produced in the same manner as in Example 15 except that the crosslinked resin particles of Comparative Example 1 were used.
The optical properties of the light diffusion films obtained in Examples 15 to 17 and Comparative Example 18 were evaluated (total light transmittance and haze were measured). The results are shown in Table 5. From these results, when the cross-linked resin particles having depressions on the surface obtained in the present invention are used as a light diffusing agent, compared with the conventional case of using cross-linked resin particles having no depressions on the surface, the same addition amount and In this case, a light diffusing film having a high haze can be obtained while maintaining the total light transmittance, and it can be seen that when the light diffusing film having the same haze is produced, the amount of the crosslinked fine particles added can be reduced.

  The vinyl-based crosslinked resin particles having a depression on the surface obtained by the present invention can be used for additives to light diffusing agents, cosmetics, paints, etc., and further used for various applications utilizing the functionality by having depressions. It can be done.

It is a conceptual diagram of the particle | grains which have a dent on the surface. 2 is a photomicrograph of the crosslinked resin particles obtained in Example 1. 2 is a photomicrograph of crosslinked resin particles obtained in Example 2. 2 is a photomicrograph of crosslinked resin particles obtained in Comparative Example 1.

Claims (7)

(A) an aqueous dispersion preparation step of preparing an aqueous dispersion by dispersing droplets of the vinyl monomer A in an aqueous medium; and (b) a vinyl monomer A in the aqueous dispersion. A method for producing vinyl-based crosslinked resin particles having an average particle diameter of 1 to 200 μm having depressions on the particle surface, including a polymerization step for polymerization,
(1) The droplet of the vinyl monomer A in the step (a) includes a plasticizer that is at least one selected from fatty acid esters and liquid paraffin, and the amount of the plasticizer added is vinyl. 0.1 to 3 parts by weight relative to 100 parts by weight of the monomer A
(2) In the step (b), the solubility parameter is 13.0-15. In a state where the polymerization conversion rate of the vinyl monomer A is 30% or more and less than 50%, or more than 80% and 95% or less. 0 (MPa) ^1/2 of a hydrocarbon compound is added to the polymerization reaction system, and (3) In the step (b), following the operation of (2), the vinyl monomer B and the crosslinking agent are added. Added to the polymerization reaction system, and the addition amount of the vinyl monomer B is 1 to 10 parts by weight with respect to 100 parts by weight of the vinyl monomer A;
A method for producing vinyl-based cross-linked resin particles.   The method for producing vinyl-based crosslinked resin particles according to claim 1, wherein the amount of the hydrocarbon compound added is 1 to 30 parts by weight with respect to 100 parts by weight of the vinyl-based monomer A.   The method for producing vinyl-based crosslinked resin particles according to claim 1 or 2, wherein the hydrocarbon compound has a boiling point of less than 60 ° C.   The vinyl monomer A contains (meth) acrylic acid ester as a main component, and the vinyl monomer B contains a vinyl aromatic compound as a main component. The manufacturing method of vinyl-type crosslinked resin particle as described in any one of.   The method for producing vinyl-based crosslinked resin particles according to claim 1, wherein the vinyl-based monomer A contains methyl (meth) acrylate and α-methylstyrene.   The method for producing vinyl-based crosslinked resin particles according to any one of claims 1 to 5, wherein the crosslinking agent added in the step (b) is divinylbenzene.   The addition amount of the crosslinking agent in the step (b) is 0.5 to 20 parts by weight with respect to 100 parts by weight of the vinyl monomer A. The vinyl crosslinked resin particles according to any one of claims 1 to 6. Production method.

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