JP5367931B2 - Vinyl-based crosslinked resin particles, production method thereof and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinylic crosslinked resin particle which has a sharp particle size distribution and contains foreign resin matters such as coarse particles, particle aggregate in such a little amount that it does not affect a coefficient of variation and moreover is substantially free from them, its manufacturing method and use thereof. SOLUTION: The vinylic crosslinked resin particle has an organic solvent content of 100 ppm or less.

Description

  The present invention relates to vinyl-based crosslinked resin particles. More specifically, for example, various improvers such as plastic film / sheet slipperiness improvers, antiblocking agents, matte finish agents, light diffusing agents, surface hardness improvers, paint and cosmetic fillers, adsorption treatments, and the like. Various fillers such as ion exchange treatment fillers, fillers that give gloss to plastic molded products, liquid crystal display spacers, electronic copying toners, standard particles for measurement and analysis, etc. Vinyl-based cross-linked resin that is useful for applications and can also be used as a pigment for paints, inks, and plastics when colored with various dyes such as acid dyes, basic dyes, fluorescent dyes and fluorescent brighteners Concerning particles.

  Conventionally, vinyl-based crosslinked resin particles obtained by polymerization of a crosslinkable vinyl monomer are known to be used in the various applications described above. As a result, the required characteristics of the vinyl-based crosslinked resin particles are becoming very high. In particular, the required characteristics are remarkable in the particle size distribution. For example, when used as a spacer for a liquid crystal display panel, the sharpness of the particle size distribution indicates the uniformity of the cell gap in each liquid crystal display panel. Directly affect the display quality such as contrast and color unevenness of the liquid crystal display panel. Therefore, recently, a very sharp vinyl-based crosslinked resin particle having a fine particle size capable of accommodating a narrow cell gap for achieving high-speed response and a coefficient of variation of about 2 to 4% has been developed. ing.

However, in spite of such vinyl-based cross-linked resin particles having excellent particle size distribution characteristics, for example, when used as a spacer for a liquid crystal display panel, although it has excellent dispersibility, individual liquid crystal displays Since the uniformity of the cell gap in the plate becomes insufficient, roughness and color unevenness may occur, resulting in a decrease in contrast, resulting in a decrease in yield of the liquid crystal display panel.
As a result of the inventor's estimation and examination of this problem, it has been found that the presence of coarse particles, particle aggregates, and the like is the cause. That is, even if the desired particle size distribution sharpness is achieved as a whole, only a large number of coarse particles or particle aggregates do not affect the coefficient of variation. It was found that the cell gap uniformity in the plate was insufficient and the above-described problems were caused.

Problems to be solved by the invention

  Therefore, the problem to be solved by the present invention is a vinyl-based material that has a sharp particle size distribution and substantially does not contain resin foreign matters such as coarse particles and particle aggregates even if it does not affect the coefficient of variation. It is in providing the manufacturing method and its use of crosslinked resin particle.

Means for solving the problem

The present inventor has intensively studied to solve the above problems, and repeatedly made various assumptions and confirmations as to how the resin foreign matter is generated.
Conventionally, vinyl-based cross-linked resin particles are usually obtained after being synthesized or processed as cross-linked resin particles and then isolated after a purification step such as wet classification using a solvent. Because it was thought that it should be removed during this classification, it was not clear how it would eventually occur. In other words, after clarifying the cause of the occurrence of the resin foreign matter, it is only necessary to find a vinyl-based crosslinked resin particle capable of eliminating the cause, and a method for obtaining such a crosslinked resin particle. I thought.

  As a result of repeated examination and trial and error based on such knowledge, the synthesized vinyl-based crosslinked resin particles penetrated the crosslinked resin particles into the crosslinked resin particles during the wet classification, and then isolated. But it was found to contain and retain organic solvents. And if there is too much content of the organic solvent, after the isolation, the resulting crosslinked resin particles themselves are particularly incompletely crosslinked in the obtained crosslinked resin particles due to the influence of the contained organic solvent. When there is a part or when the glass transition temperature is low, the part is gradually softened or made to be sticky, and fusion and aggregation between the crosslinked resin particles occur in the storage stage and use stage after isolation. It has been noticed that it tends to occur and becomes a cause of resin foreign matter such as aggregated particles and coarse particles.

Therefore, if the amount of the organic solvent contained in the vinyl-based crosslinked resin particles is not more than a specific amount, it is considered that the above problems can be solved at once, and the present invention has been completed by confirming that.
Moreover, if the method for producing vinyl-based crosslinked resin particles using a solvent containing an aliphatic and / or aromatic hydrocarbon as an essential component as a solvent serving as a dispersion medium at the time of classification, the above problems can be solved at once. This was confirmed and the present invention was completed.
That is, the vinyl-based crosslinked resin particles according to the present invention have an organic solvent content in the crosslinked resin particles of 100 ppm or less.

Also, the method for producing vinyl-based crosslinked resin particles according to the present invention classifies and isolates particles obtained by radical polymerization of a radically polymerizable monomer containing a crosslinkable vinyl monomer in a state dispersed in a solvent. In the method for producing resin particles including a step, a solvent containing an aliphatic and / or aromatic hydrocarbon as an essential component is used as the solvent.
It is characterized by that.
Moreover, the spacer for liquid crystal display panels concerning this invention uses the vinyl type crosslinked resin particle concerning the said invention.

Embodiment of the Invention

Hereinafter, the vinyl-type crosslinked resin particle concerning this invention, its manufacturing method, and its use are demonstrated in order.
The vinyl-based crosslinked resin particles according to the present invention (hereinafter sometimes referred to as the vinyl-based crosslinked resin particles of the present invention) are not particularly limited, but specifically, structural units derived from a crosslinkable vinyl monomer are used. The particles are preferably made of a crosslinked resin.
In the vinyl-based crosslinked resin particles of the present invention, the amount of organic solvent contained in the crosslinked resin particles (organic solvent content) is 100 ppm or less, preferably more than 0 ppm and 100 ppm or less, and still more preferably 0.01 to 50 ppm, most preferably 0.1-10 ppm. When the content of the organic solvent exceeds 100 ppm, the crosslinked resin particles themselves are softened or become sticky in the storage stage or use stage of the vinyl-based crosslinked resin particles of the present invention. Fusion and fusion occur between the resin particles, and foreign particles such as aggregated particles and coarse particles are generated. In this way, when aggregated particles, coarse particles, etc. are generated, even if the generated amount is in a range that does not affect the coefficient of variation of the particle size distribution, for example, when used as a spacer for a liquid crystal display panel As a result, the uniformity of the cell gap in each liquid crystal display panel is lowered, and the display quality is adversely affected. Similarly, for example, when used as a film filler (light diffusing agent, anti-blocking agent, lubricant, etc.), it may be easily removed from the film, and its characteristics may not be fully exhibited. Further, it is preferable that a small amount of an organic solvent is present in the above-mentioned range in the crosslinked resin particles because, for example, when used as a spacer for a liquid crystal display panel, dispersibility in a spraying solvent is improved in wet spraying.

As described above, the vinyl-based crosslinked resin particles of the present invention are preferably particles composed of a resin containing a structural unit derived from a crosslinkable vinyl monomer capable of radical polymerization, and there are a plurality of crosslinked forms, for example. Crosslinking by a radically polymerizable unsaturated group that did not participate in the polymerization among radically polymerizable unsaturated groups or other reactive functional groups may be used, and there is no particular limitation.
The crosslinkable vinyl monomer is not particularly limited, and specific examples of the crosslinkable vinyl monomer having a plurality of radically polymerizable unsaturated groups include, for example, divinylbenzene, 1,4- Vinyl compounds such as divinyloxybutane and divinylsulfone;
Allyl compounds such as diallyl phthalate and its isomers, triallyl isocyanurate and its derivatives, triallyl trimetate;
(Poly) oxyalkylene glycol di (meth) acrylates such as (poly) ethylene glycol di (meth) acrylate and (poly) propylene glycol di (meth) acrylate;
Pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate , Glycerol tri (meth) acrylate, glycerol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylolpropane tetra ( (Meth) acrylic compounds such as (meth) acrylate;
Etc. Similarly, among the crosslinkable vinyl monomers, examples of the crosslinkable vinyl monomer having a reactive functional group other than a radically polymerizable unsaturated group include an epoxy group as a reactive functional group. Radical polymerizable vinyl monomers having an amino group, a carboxyl group, a hydroxyl group, a thiohydroxyl group (SH group), etc., specifically, hydroxyethyl (meth) acrylate, dimethylaminoethyl (meta) ) Acrylate, glycidyl (meth) acrylate, (meth) acrylic acid, (meth) acrylamide and the like are preferred. These crosslinkable vinyl monomers may be used alone or in combination of two or more.

In the vinyl-based crosslinked resin particles of the present invention, the structural unit derived from the crosslinkable vinyl monomer is not particularly limited, but is preferably 1 to 100% by weight, more preferably 3 to 90% by weight, Even more preferably, it is 5 to 80% by weight. If it is less than 1% by weight, the degree of crosslinking in the particles will be low, and it will be difficult to express desired hardness, heat resistance, solvent resistance, etc. If it is too much, unreacted vinyl groups will likely remain. Depending on the application, it may not be preferable.
In the vinyl-based crosslinked resin particles of the present invention, in addition to the structural unit derived from the crosslinkable vinyl monomer, a structural unit derived from a non-crosslinkable vinyl monomer capable of radical polymerization, and other radical polymerizable monomers It may contain structural units derived from the body.

Although it does not specifically limit as said non-crosslinkable vinyl monomer, Specifically, for example, styrene, p- (m-) methylstyrene, p- (m-) ethylstyrene, p- (m-) Styrene such as chlorostyrene, p- (m-) chloromethylstyrene, styrenesulfonic acid, p- (m-) t-butoxystyrene, α-methyl-pt-amyloxystyrene, pt-amyloxystyrene System monomers;
(Meth) ethyl acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) (Meth) acrylic acid ester monomers such as acrylate, hydroxyethyl (meth) acrylate, diethylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, butanediol mono (meth) acrylate;
Unsaturated carboxylic monomers such as (meth) acrylic acid and maleic acid;
Alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether;
Vinyl ester monomers such as vinyl acetate and vinyl butyrate;
(Meth) acrylonitrile, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide;
Etc. These may be used alone or in combination of two or more.

The other radical polymerizable monomer is not particularly limited, but specifically, for example, the vinyl-based crosslinked resin particles of the present invention,
In the case of imparting hydrophilicity, monomers having a hydroxyl group such as hydroxyethyl (meth) acrylate; monomers having a polyethylene glycol component such as methoxypolyethylene glycol (meth) acrylate; These may be used alone or in combination of two or more.
Similarly, in order to impart hydrophobicity, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, pentanefluoropropyl (meth) acrylate, octafluoroamyl (meth) acrylate, heptadecafluorodecyl (meta ) Fluorine atom-containing (meth) acrylates such as acrylate and perfluorobutylethyl (meth) acrylate; These may be used alone or in combination of two or more.

In the vinyl-based crosslinked resin particles of the present invention, the structural unit derived from the non-crosslinkable vinyl monomer and the structural unit derived from another radical polymerizable monomer contain the structural unit derived from the crosslinkable vinyl monomer. It may be included outside the range of the ratio.
In the vinyl type crosslinked resin particles of the present invention, the average particle size is preferably 0.5 to 50 μm, more preferably 1.0 to 40 μm, and even more preferably 1.5 to 30 μm. In particular, when the vinyl-based crosslinked resin particles of the present invention are used as a spacer for a liquid crystal display panel as described later, the average particle diameter is preferably 1.0 to 30 μm, more preferably 1.0. It is ˜25 μm, more preferably 1.0 to 20 μm.

Similarly, the particle size distribution of the vinyl-based crosslinked resin particles of the present invention preferably has a coefficient of variation of 1 to 50%, more preferably 2 to 40%, and even more preferably 2 to 30%. In particular, when the vinyl-based crosslinked resin particles of the present invention are used as a spacer for a liquid crystal display panel as described later, the coefficient of variation is preferably 1 to 10%, more preferably 2 to 8%. Even more preferably, it is 2 to 6%.
In the vinyl-based crosslinked resin particles of the present invention, its use is not particularly limited. Specifically, for example, a plastic film / sheet slipperiness improver, an anti-blocking agent, a matte finish, Various modifiers such as light diffusing agents and surface hardness improvers, fillers for paints and cosmetics, fillers for treatment such as adsorption treatment and ion exchange treatment, and fillers that give gloss to plastic molded products It is useful for various applications such as fillers, spacers for liquid crystal display panels and their materials, and standard particles for measurement and analysis.

In addition, by introducing dyes and / or pigments to color the organic-inorganic composite particles, they can also be used as pigments for paints, inks and plastics, coloring spacers for liquid crystal display panels, and the like.
The color for coloring the organic-inorganic composite particles is preferably a color that does not transmit light. When colored with a color that does not transmit light, for example, when the organic-inorganic composite particles of the present invention are used as a spacer for a liquid crystal display panel, light leakage can be prevented and the image quality contrast can be improved. Examples of the color that does not transmit light include black, dark blue, amber, purple, blue, dark green, green, brown, red, and the like, with black, dark blue, and amber being particularly preferable.

  Although it does not specifically limit as said dye, Specifically, various dyes, such as a disperse dye, a reactive dye, a sulfur dye, an acidic dye, a basic dye, a fluorescent dye, and a fluorescent whitening agent, are mentioned, for example. Specific examples of these various dyes are “Chemical Handbook Applied Science Edition, Chemical Society of Japan” (published by Maruzen Co., Ltd.), pages 1399 to 1427, “Nippon Kayaku Dye Handbook” (published by Nippon Kayaku Co., Ltd. )It is described in. The color mentioned above is mentioned as a color of dye and dyeing | staining. Of these various dyes, basic dyes are preferred. This is because the silanol group in the polysiloxane skeleton is acidic, so that the basic (cationic) dye is easily adsorbed and dyed.

Specific examples of the pigment include, but are not limited to, inorganic pigments such as carbon black, iron black, chrome vermilion, molybdenum red, red pepper, yellow lead, chrome green, cobalt green, ultramarine blue, and bitumen; There are organic pigments such as phthalocyanine, azo, and quinacridone. However, since the pigment may not be introduced into the organic-inorganic composite fine particles of the present invention unless the average particle size is 0.4 μm or less, it is preferable to use the above dye.
The spacer for a liquid crystal display panel according to the present invention is a spacer formed by using the vinyl-based crosslinked resin particles of the present invention. Since the vinyl-based crosslinked resin particles of the present invention are substantially free from resin foreign matter, they are particularly preferably used as spacers for liquid crystal display panels and their materials among the various uses described above.

  The spacer for a liquid crystal display panel according to the present invention has a specific physical property by subjecting the vinyl cross-linked resin particles of the present invention to some kind of treatment, even if the vinyl cross-linked resin particles of the present invention themselves are used as a spacer. It may be used as, and is not particularly limited, and a useful spacer can be used in any form. For example, an adhesive spacer for a liquid crystal display panel in which an adhesive layer is formed by attaching or grafting a resin or the like to the surface of the vinyl-based crosslinked resin particle of the present invention as a particle body, or the vinyl of the present invention Colored spacers for liquid crystal display plates that are colored by adding dyes to the reaction system at the time of synthesis of the crosslinked resin particles, or adhesion for liquid crystal display plates that combine these adhesive and coloring functions Preferred examples include a colored spacer.

The method for producing vinyl-based crosslinked resin particles according to the present invention (hereinafter sometimes referred to as the production method of the present invention) is a particle obtained by radical polymerization of a radically polymerizable monomer containing a crosslinkable vinyl monomer. Is classified and isolated in a state where it is dispersed in a solvent containing an aliphatic and / or aromatic hydrocarbon as an essential component.
In the production method of the present invention, classification is an operation for selecting particles having a desired particle diameter in a state where the synthesized vinyl-based crosslinked resin particles are dispersed in a solvent as described above. After classification, the selected vinyl-based crosslinked resin particles are obtained in a state of being dispersed in a solvent. In addition, the isolation means that only the vinyl crosslinked resin particles are taken out from the state after classification, that is, the vinyl crosslinked resin particles selected by classification are dispersed in the solvent, and the solvent is removed. To do.

First, the process of obtaining the particles, that is, the process of synthesizing vinyl-based crosslinked resin particles (before classification) by the radical polymerization will be described.
The vinyl-based crosslinked resin particles (before classification) are particles obtained by radical polymerization of a radical polymerizable monomer containing a crosslinkable vinyl monomer, and the crosslinkable vinyl monomer is not particularly limited. Specifically, for example, the crosslinkable vinyl monomers listed as the derived monomers in the structural unit of the vinyl-based crosslinked resin particle of the present invention can be preferably exemplified. By using these cross-linkable vinyl monomers, cross-linked resin particles can be obtained, but the cross-linking form is not particularly limited, and a desired cross-linkage depends on the type of cross-linkable vinyl monomer used. Specifically, for example, among a plurality of radically polymerizable unsaturated groups, for example, crosslinking by radically polymerizable unsaturated groups that did not participate in polymerization, for example, crosslinking by dehydration condensation of hydroxyl groups and epoxy And other functional groups having reactivity such as crosslinking by reaction of a group and an amino group.

In the production method of the present invention, the crosslinkable vinyl monomer in the radical polymerizable monomer is not particularly limited, but is preferably used in an amount of 1 to 100% by weight, more preferably 3 to 90% by weight. Even more preferably, it is 5 to 80% by weight. If the amount of the crosslinkable vinyl monomer used is less than 1% by weight, the degree of crosslinking in the resulting resin particles will be low, and the desired hardness, heat resistance, solvent resistance, etc. will be less likely to be exhibited, and too much. And unreacted vinyl groups are likely to remain, which may be undesirable depending on the application.
The radical polymerizable monomer may include a radical polymerizable monomer other than the crosslinkable vinyl monomer, and is not particularly limited. Preferable examples include non-crosslinkable vinyl monomers and other radical polymerizable monomers listed as derived monomers in the structural unit of the vinyl-based crosslinked resin particles of the present invention.

In the production method of the present invention, among the radical polymerizable monomers, radical polymerizable monomers other than the crosslinkable vinyl monomer, that is, non-crosslinkable vinyl monomers and other radical polymerizable monomers. May be contained outside the range of the content of the crosslinkable vinyl monomer.
Specific examples of the method for synthesizing the vinyl-based crosslinked resin particles (before classification) include (a) precipitation polymerization, (b) seed polymerization, and (c) suspension polymerization. Any synthetic method that is generally used in a method for producing crosslinked resin particles may be used, and the method is not particularly limited.

In the (a) precipitation polymerization, the radical polymerizable monomer is radical polymerized in a solvent in which the monomer is soluble and a resin obtained by synthesizing the monomer is insoluble. During the polymerization, a dispersion stabilizer described later is dissolved in the solvent. According to such a polymerization method, the obtained resin is precipitated in the solvent as spherical resin particles having a relatively uniform particle size.
Although it does not specifically limit as said solvent, Specifically, For example, lower alcohol, such as methanol, ethanol, isopropanol, n-butanol, or the mixed solvent of this lower alcohol and water, or n-hexane, Preferred examples include inorganic solvents such as n-heptane. These may be used alone or in combination of two or more.

  The dispersion stabilizer is preferably a polymer soluble in the solvent, and is not particularly limited. Specifically, for example, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyvinyl alcohol, polyvinyl alkyl ether And various polymers such as methyl cellulose, ethyl cellulose, polyethylene oxide, polyethylene imine, polyethylene glycol, acrylic acid-styrene block copolymer, polyethylene glycol-methyl methacrylate copolymer, polystyrene, polymethyl methacrylate, and polyvinyl acetate. It is done. These may be used alone or in combination of two or more.

In the above precipitation polymerization, a surfactant may be used together with the polymer to be the dispersion stabilizer. The surfactant is not particularly limited. Specifically, for example, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, and a polymer interface. Examples thereof include an activator and a polymerizable surfactant having one or more polymerizable carbon-carbon unsaturated bonds in the molecule. These may be used alone or in combination of two or more.
In the above precipitation polymerization, the polymerization is preferably performed in the presence of a radical polymerization initiator, but the polymerization may be initiated using heat, ultraviolet rays, radiation, electron beams, etc. without using a radical polymerization initiator. . This is preferably the same in seed polymerization and suspension polymerization described later.

The radical polymerization initiator is not particularly limited. Specifically, for example, peroxide initiators, and redox initiators in which the peroxide initiators are combined with a reducing agent are used. Preferred examples include azo compounds. These radical polymerization initiators may be used alone or in combination of two or more.
There is no particular limitation on the addition of the radical polymerization initiator, and the whole amount may be charged at the beginning (before the start of the reaction), or a portion may be charged first and then the rest may be added continuously. A pulse may be added or a combination of both may be added.

In the precipitation polymerization, the solvent and the radical polymerizable monomer are polymerized with stirring in a reactor equipped with a stirrer, a condenser, a thermometer, etc. in the presence of the radical polymerizable initiator. It is preferable.
In the precipitation polymerization, the polymerization temperature is not particularly limited, but it is usually preferably 40 to 100 ° C, more preferably 50 to 90 ° C, and still more preferably 55 to 85 ° C. At this time, it is particularly preferable to carry out in an inert gas atmosphere such as nitrogen gas and / or argon gas. These points are preferably the same in seed polymerization and suspension polymerization described later.

In the above (b) seed polymerization, polymer fine particles are dispersed in a dispersion in which a solvent (swelling agent) that swells the polymer fine particles is dispersed in water, and the swelled aqueous dispersion of the polymer fine particles is dispersed. Then, the radical polymerizable monomer is mixed in the aqueous dispersion, and the radical polymerizable monomer is absorbed by the swelling body of the polymer fine particles and radical polymerization is performed. According to such a polymerization method, the obtained resin becomes spherical resin particles having a relatively uniform particle diameter, as in the above-described precipitation polymerization.
The swelling agent is not particularly limited. Specifically, for example, methanol, ethanol, n-butanol, ethyl acetate, n-butyl acetate, acetone, methyl ethyl ketone, toluene, xylene, n-hexane, n-heptane. Preferred examples include organic solvents such as n-octane, methylene chloride, 1,2-dichloroethane, 1,2,3-trichloroethylene, 1-chlorododecane, dimethylformamide and tetrahydrofuran. These may be used alone or in combination of two or more.

The polymer fine particles are particles used as seed particles, and are polymer fine particles that can swell in an organic solvent that is a swelling agent. Although it does not specifically limit as this polymer fine particle, Specifically, a polystyrene, poly (meth) acrylate, a styrene- (meth) acrylate copolymer etc. are mentioned, for example. These may be used alone or in combination of two or more.
In order to stably disperse the polymer fine particles and the swelling agent in water, it is preferable to use the surfactant described in the above precipitation polymerization method, or an aqueous polymer such as carboxymethylcellulose, sodium alginate, or sodium polyacrylate. These may be used alone or in combination of two or more.

Although it does not specifically limit as said radical polymerization initiator, Specifically, it is preferable that it is the same as that of the radical polymerization initiator enumerated in the said precipitation polymerization method, for example. Usually, the radical polymerization initiator is used after dissolved in the swelling agent and / or the radical polymerizable monomer.
There is no particular limitation on the addition of the radical polymerization initiator, and the whole amount may be charged at the beginning (before the start of the reaction), or a portion may be charged first and then the rest may be added continuously. A pulse may be added or a combination of both may be added.

In the seed polymerization, when the polymer fine particles and the swelling agent are dispersed as described above, the polymer fine particles are swollen by the swelling agent, and a swollen aqueous dispersion is prepared. Then, a radically polymerizable monomer is added to the aqueous dispersion of the swelled body so that the swellable body absorbs the radically polymerizable monomer and performs radical polymerization.
In the suspension polymerization (c), the radical polymerizable monomer and the radical polymerizable monomer are dispersed by stirring with a solvent (particularly preferably water) that does not dissolve or slightly dissolves. However, radical polymerization is performed in the presence of a radical polymerization initiator.

In order to stably disperse the radical polymerizable monomer in a solvent (particularly preferably water), as the dispersion stabilizer, the surfactant described in the precipitation polymerization method; the aqueous polymer described in the seed polymerization method; sulfuric acid It is preferable to use sparingly water-soluble inorganic salts such as barium, calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, and calcium phosphate; These may be used alone or in combination of two or more.
Although it does not specifically limit as said radical polymerization initiator, Specifically, it is preferable that it is the same as that of the radical polymerization initiator enumerated in the said precipitation polymerization method, for example. Usually, the radical polymerization initiator is used after dissolved in the swelling agent and / or the radical polymerizable monomer.

In the suspension polymerization, the solvent (particularly preferably water) and the radical polymerizable monomer are placed in a reactor equipped with a stirrer, a condenser, a thermometer, etc. in the presence of the radical polymerizable initiator. It is preferable to polymerize with stirring.
When the crosslinkable vinyl monomer having a plurality of radical polymerizable double bond groups is contained in the radical polymerizable monomer used in the various synthesis methods (a) to (c), the crosslinkable vinyl is used. Depending on the monomer, the polymerization of the radical polymerizable monomer proceeds, and the crosslinking of the polymers by a plurality of radical polymerizable double bond groups also proceeds.

In the production method of the present invention, the obtained vinyl-based crosslinked resin particles can be colored particles, and in that case, it is preferable to carry out in a state in which a dye is included in the synthesis reaction system.
Although it does not specifically limit as said dye, Specifically, an acidic dye, a basic dye, a fluorescent dye, a fluorescent brightening agent etc. are preferable, and since an acid dye has high heat resistance of dye, it is more preferable.
In order to separate and dry the vinyl-based crosslinked resin particles (before classification) obtained by the various synthesis methods (a) to (c) from the solvent or the solvent, a conventionally known method may be used. For example, there are various separation methods such as separation by natural sedimentation or centrifugal sedimentation and decantation, separation by filtration, etc. If necessary, washing may be performed. Examples of drying include various drying methods such as natural drying, reduced pressure drying, and hot air drying. Prior to the separation, a separation agent can be promoted by adding an aggregating agent such as aluminum sulfate. The vinyl-based cross-linked resin particles (before classification) obtained by the above separation and drying are easily spherical and have a relatively uniform particle size as easily as the cured resin particles in the emulsion with a very light force such as a ball mill. It can be set as the crosslinked resin particle which has.

The average particle diameter of the vinyl-based crosslinked resin particles (before classification) is not particularly limited, but may be adjusted to about 0.5 to 50 μm, more preferably 1.0 to 40 μm. Even more preferably, it is 1.5 to 30 μm. Further, the particle size distribution is not particularly limited, but when used for a spacer for a liquid crystal display panel, it may be prepared so that the coefficient of variation is about 1 to 20%, more preferably 2 to 15%, Even more preferably, it is 2 to 10%.
Hereinafter, the process of classifying and isolating the vinyl-based crosslinked resin particles (before classification) synthesized as described above will be described.

  In the vinyl-based crosslinked resin particles obtained by the production method of the present invention, the vinyl-based crosslinked resin particles (before classification) are aliphatic and / or aromatic hydrocarbons (hereinafter sometimes simply referred to as hydrocarbons). Vinyl-based crosslinked resin particles obtained by classification and isolation in a state of being dispersed in a solvent contained as an essential component. As a solvent used for classification, by using a solvent essential for aliphatic and / or aromatic hydrocarbons, the organic solvent content of the vinyl-based crosslinked resin particles obtained after isolation is 100 ppm or less, preferably more than 0 and It can be 100 ppm or less, More preferably, it is 0.1-50 ppm or less, More preferably, it can be 0.1-10 ppm. If the content of the organic solvent is 100 ppm or less, after isolation, the obtained crosslinked resin particles themselves, particularly when there are incompletely crosslinked parts in the obtained crosslinked resin particles, It can be prevented from gradually softening or becoming sticky. As a result, fusion and aggregation of crosslinked resin particles in the storage stage and use stage after isolation are suppressed, and aggregated particles and coarse particles are suppressed. It is possible to prevent the generation of resin foreign matter such as. In addition, it is preferable that a small amount of an organic solvent is present in the crosslinked resin particles within the above range, for example, when used as a spacer for a liquid crystal display panel, because dispersibility in a spraying solvent is improved in wet spraying.

  In the solvent containing the aliphatic and / or aromatic hydrocarbon as an essential component, the aliphatic hydrocarbon is not particularly limited, but specifically, an aliphatic hydrocarbon having 4 to 20 carbon atoms. It is preferably at least one selected from among, more preferably at least one selected from aliphatic hydrocarbons having 5 to 15 carbon atoms, and even more preferably selected from aliphatic hydrocarbons having 6 to 10 carbon atoms. At least one. If the number of carbon atoms is less than 4, the vapor pressure is high, and thus vaporizes during classification, making it unsuitable for classification. If it exceeds 20, the solvent tends to remain in the particles, which is not preferable. Among the above aliphatic hydrocarbons, for example, hexanes such as n-hexane and cyclohexane; heptanes such as n-heptane; octanes such as n-octane; decanes such as n-decane are more preferable. However, hexanes are even more preferred.

Similarly, the aromatic hydrocarbon is not particularly limited, but specifically, it is preferably at least one selected from aromatic hydrocarbons having 6 to 20 carbon atoms, more preferably. Is at least one selected from aromatic hydrocarbons having 6 to 15 carbon atoms, and more preferably at least one selected from aromatic hydrocarbons having 6 to 10 carbon atoms. When the number of carbon atoms exceeds 20, the solvent tends to remain in the particles, which is not preferable. Among the aromatic hydrocarbons, for example, toluene, xylene and the like are more preferable.
In particular, the aliphatic hydrocarbon is more preferable than the aromatic hydrocarbon in that it hardly permeates and remains in the vinyl-based crosslinked resin particles. Among them, hexanes, heptanes and octanes are particularly preferable, and hexanes are preferable. Most preferred.

In the solvent, the total content of the essential hydrocarbons is preferably 20 to 100% by volume, more preferably 25 to 100% by volume, and even more preferably 30 to 95% by volume. When the content is less than 25% by volume, the incompletely cured resin component is easily dissolved in the solvent.
The solvent may further contain another solvent in addition to the hydrocarbon which is an essential component.
The other solvent is not particularly limited, but in the case where the solvent is only a hydrocarbon which is an essential component, the dispersibility of the vinyl-based crosslinked resin particles in the solvent may be lowered. A solvent capable of enhancing the dispersibility of the vinyl-based crosslinked resin particles therein is preferred. Specifically, such a solvent is preferably at least one polar solvent selected from the group consisting of alcohol, ketone, cellosolve, ether and ester, and more preferably alcohol, ether, ketone and It is at least one polar solvent selected from the group consisting of cellosolve, even more preferably alcohol, particularly preferably methanol, ethanol, 1-propanol and 2-propanol, most preferably ethanol.

  When the other solvent is included, particularly when the polar solvent listed above is included, the content ratio of the various solvents is 30 to 95% by volume of the hydrocarbon and 5 to 70 volume of the polar solvent in the total amount of the solvent. %, More preferably 40 to 90% by volume of the hydrocarbon and 10 to 60% by volume of the polar solvent, still more preferably 50 to 80% by volume of the hydrocarbon and 20 to 20% of the polar solvent. 50% by volume. When the content ratio of the polar solvent is less than 5% by volume, the dispersibility of the vinyl-based crosslinked resin particles in the solvent may be decreased, and aggregation and the like may be increased, and the yield of classification may be decreased. There is a possibility that the content of the organic solvent which penetrates into the vinyl-based crosslinked resin particles and remains after the isolation will be excessive, and the same problem as the above-described conventional problem will occur.

  Regarding the dispersion, the dispersion after the vinyl-based crosslinked resin particles (before classification) are dispersed in the solvent is dispersed so that the content of the vinyl-based crosslinked resin particles (before classification) is 1 to 80% by weight. It is preferable to be 5 to 75% by weight, still more preferably 10 to 70% by weight. When the content ratio is less than 1% by weight, much time is required for the subsequent classification. When the content ratio exceeds 80% by weight, it is difficult to disperse the resin particles in the solvent. Occasionally clogging, etc., resulting in reduced classification efficiency and accuracy, resulting in longer time required for classification, or a large amount of addition required to perform classification in a short time, classifiers, etc. May cause damage.

In addition, various dispersants may be added to the solvent in order to improve the dispersibility of the resin particles.
As for the classification, the method is not particularly limited, but in the present invention, since the resin particles are classified in a state of being dispersed in a solvent, it is assumed that the classification is performed by a wet method.
An apparatus for classification is not particularly limited. For example, a cyclone, a sedimentation tower, or a sieve is preferably used. In addition, the sieve performs classification based on whether or not it passes through a certain opening. For example, a sieve with fine lines is used for those having an opening of 10 μm or more, for example, those having an opening of 20 μm or less. For example, a metal foil or the like that has fine holes formed by etching or a screen that has rectangular holes by plating, which is called an electroformed screen, is used. The opening is very well aligned and classification accuracy can be improved. In particular, the electroformed screen is capable of drilling holes smaller than the thickness compared to those formed by etching, and is an excellent sieve with a clean cross-sectional shape without side edges. It is particularly preferable to perform classification. Hereinafter, the electric sieve will be described in detail.

  The electroformed sieve is a screen having a rectangular hole formed by plating. As a method of producing an electroformed sieve, a conductive coating is formed on a glass plate that has been corroded in a highly accurate cross-line shape by physical plating such as vacuum deposition or sputtering, or chemical plating such as electrolytic plating or electroless plating. Then, the plating layer other than the groove of the corroded portion is removed, and a mesh is formed thereon by a method such as electrolytic plating, and then peeled off from the glass original plate. The mesh produced in this manner may be further subjected to electrolytic plating as necessary after peeling from the glass original plate. In addition, as another manufacturing method, after forming a conductive film on a glass plate by vacuum plating, physical plating such as sputtering, or chemical plating such as electrolytic plating or electroless plating, and applying a resist on the film, There is also a method in which a pattern having a predetermined shape is formed, and then portions other than the pattern are removed by etching, and after peeling from the glass original plate, electrolytic plating is performed.

Gold, platinum, silver, copper, iron, aluminum, nickel, and various alloys based on these are used as the material for the electroformed screen. Nickel is used because of its durability, corrosion resistance, and ease of plating. Those having a main component are particularly preferably used.
In addition to easy adjustment of the aperture diameter and the number of apertures per unit, the electroformed sieve has a very good aperture diameter distribution, so it can be classified with high accuracy when used as a sieve. It becomes.
Electroformed screens are so thin that they can be easily damaged or torn, and there is a risk of contamination by metallic impurities into the classified particles. In particular, when the classified vinyl-based crosslinked resin particles are used for electronic materials such as spacers for liquid crystal display panels, the incorporation of metal-based impurities is a serious problem because it causes deterioration in quality and reliability. For this reason, it is preferable to increase the strength by providing a grid-like or ring-like support on one side or both sides of the electric sieve.

Regarding the attachment of the screened sieve to the classifier, especially when applying ultrasonic vibration, the screened sieve and the classifier may rub against each other, causing the screened sieve to break down and contaminating the classified particles with metal impurities. Therefore, it is preferable to attach via a member made of an elastomer. The ultrasonic vibrator is preferably a chip made of ceramics in order to avoid mixing of metal impurities.
In the classification using an electric sieve, wet classification is performed by passing a dispersion (dispersion liquid) of resin particles through a classification apparatus equipped with an electric sieve. Compared with the dry method using an inert gas or air as a medium, the wet method has higher ultrasonic irradiation efficiency and dispersion stability, and the particles are less adhered to the electric sieve. In particular, those having a small particle diameter used for spacers for liquid crystal display panels and the like have strong cohesion, so that the dry method may cause insufficient dispersion. In the wet method, the liquid medium in which the particles are dispersed can be appropriately selected depending on the material of the electroforming sieve to be used, the pore diameter, the number of lines, the particle properties, the particle size distribution, and the like. In classification, when an ultrasonic irradiation chip is inserted into the classification device, the efficiency of classification can be improved by performing ultrasonic irradiation on a liquid medium such as water.

When classification is performed using an electroformed sieve, it is preferable to use a solvent having a viscosity of 50 cP or less, more preferably 20 cP or less. The solvent in which the resin particles are dispersed can be appropriately selected depending on the material of the electric sieve to be used, the pore diameter, the number of lines, the properties of the resin particles or the particle size distribution, but is as low as possible to increase the classification speed. Viscosity is preferred.
When classification is performed with an electroformed screen, particularly when a small particle size of about 10 μm or less used for a liquid crystal display panel spacer is classified, the tendency to clog the electroformed screen becomes strong. In order to bring the concentration of the resin particles in the dispersion in the classifier into the above range, a solvent may be added as appropriate. Further, if the resin particle concentration in the system varies due to classification, the classification speed may change or the classification accuracy may change. Therefore, it is preferable to suppress the variation in the resin particle concentration by adding an appropriate solvent.

  When classification is performed using an electroforming sieve, it is preferable to flow at least a part of the dispersion in the classifier. As a result, it is possible to prevent concentration changes due to sedimentation and the like, and accumulation of particles on the electroforming sieve. Examples of the method of flowing at least a part of the dispersion include a method of stirring the dispersion with a stirring blade or the like, and a method of circulating at least a part of the dispersion by sucking and discharging with a pump. When circulating the dispersion by a pump, the discharge of the dispersion returning to the classifier is made to collide with the electric sieve surface, and the angle between the discharge direction and the electric sieve surface is preferably 30 to 90 degrees, more preferably When the angle is set to 45 to 90 degrees, it is possible to more effectively prevent particles from being deposited on the surface of the electroforming sieve. There is no particular limitation on the flow rate during circulation, but if it is too large, there is a possibility that metallic impurities may be mixed into the classified resin particles by damaging the electric sieve, and if too small, the flow effect of the dispersion will be reduced. 0.1 to 10 L / min is appropriate.

  When classifying by an electroforming sieve, the temperature of the solvent and / or dispersion during classification is preferably 0 to 100 ° C, more preferably 5 to 70 ° C, and even more preferably 5 to 60 ° C. By being in this temperature range, classification can be performed without impairing the functions of the particles, the solvent and the electroforming sieve. In addition, for example, in the case where properties change greatly due to temperature changes such as adhesive spacer particles having a thermoplastic resin component on the particle surface, a solvent at a constant temperature is additionally supplied, or the wetted part of the apparatus It is preferable to reduce the temperature change by providing a jacket to control the temperature, or when circulating the dispersion as described above, introducing a heat exchanger to the circulation line to control the temperature. . The width of the temperature change during classification is preferably within 30 ° C, and more preferably within 20 ° C.

When classification is performed using an electroforming sieve, it is preferable to keep the amount of liquid in the classification apparatus during classification constant. By keeping the liquid amount constant, the temperature, the concentration of particles in the system, the magnitude of ultrasonic vibration, and the like can be kept constant, so that changes in classification speed and classification accuracy can be suppressed. Here, keeping the liquid amount constant means that the change in the liquid amount is within 30%, preferably within 20%.
The vinyl-based crosslinked resin particles of the present invention are preferably prepared by the above classification so as to have an average particle diameter of 0.5 to 50 μm, more preferably 1.0 to 40 μm, and still more preferably 1.5 to 30 μm. In particular, when the vinyl-based crosslinked resin particles of the present invention are used as a spacer for a liquid crystal display panel, the average particle diameter is preferably adjusted to be 1.0 to 30 μm, more preferably 1.0. It is ˜25 μm, more preferably 1.0 to 20 μm.

Similarly, for the particle size distribution, the coefficient of variation is preferably 1 to 50%, more preferably 2 to 40%, and even more preferably 2 to 30%. In particular, when the vinyl-based crosslinked resin particles of the present invention are used as a spacer for a liquid crystal display panel, the coefficient of variation is preferably adjusted to be 1 to 10%, more preferably 2 to 8%. Even more preferably, it is 2 to 6%.
In the production method of the present invention, the classified vinyl-based crosslinked resin particles are isolated after the wet classification. The isolation method is not particularly limited, and examples thereof include centrifugation, decantation, and a method of evaporating the solvent.

  In the manufacturing method of this invention, it is preferable that the process which eliminates the incomplete bridge | crosslinking of a vinyl type crosslinked resin particle is made | formed. Specifically, the vinyl-based crosslinked resin particles (before classification) obtained by the above synthesis are classified and isolated, and finally obtained as vinyl-based crosslinked resin particles. It is preferable that the cross-linking process is performed again so that an incomplete cross-linked portion can be cross-linked, and the number of treatments and the type of the treatment are not particularly limited as long as they are within the above period. By performing the treatment for eliminating the incomplete crosslinking, the degree of crosslinking in the individual vinyl-based crosslinked resin particles can be further increased, thereby further solving the above-described problems caused by the organic solvent remaining in the crosslinked resin particles. Can be reduced.

  The treatment for eliminating the incomplete crosslinking is not particularly limited as long as the treatment further promotes crosslinking in the crosslinked resin particles. For example, heating is preferable. It is more preferable to heat the vinyl-based crosslinked resin particles during separation or after isolation. At this time, the temperature of the heat treatment is not particularly limited, but is preferably 30 ° C. or higher, more preferably 40 to 200 ° C., and still more preferably 50 to 180 ° C. The time for the heat treatment is not particularly limited, but is preferably 10 minutes to 24 hours, more preferably 10 minutes to 10 hours, and even more preferably 10 minutes to 4 hours.

  The vinyl-based crosslinked resin particles obtained by the production method of the present invention are not particularly limited in use, for example, plastic film / sheet slipperiness improver, anti-blocking agent, matte finish agent, light diffusion Various kinds of fillers, such as various improvers such as adhesives and surface hardness improvers, fillers for paints and cosmetics, fillers for treatment such as adsorption treatment and ion exchange treatment, and fillers that give gloss to plastic molded products In addition, it is useful for various applications such as spacers for liquid crystal display panels and their materials, standard particles for measurement / analysis, etc., and is also colored by various dyes such as acid dyes, basic dyes, fluorescent dyes and fluorescent brighteners. For example, it can also be used as a pigment for coloring paints, inks and plastics, a coloring spacer for liquid crystal display panels, and the like.

Since the vinyl-based crosslinked resin particles obtained by the production method of the present invention are substantially free from resin foreign matter, they are particularly preferably used as a spacer for a liquid crystal display panel among the various uses described above.
When the vinyl-based crosslinked resin particles obtained by the production method of the present invention are used as a spacer for a liquid crystal display panel, even if the vinyl-based crosslinked resin particles themselves are used as a spacer, the vinyl-based crosslinked resin particles are subjected to some treatment. Even if it is used as a spacer having specific physical properties, it can be a useful spacer, and is not particularly limited. For example, an adhesive spacer for a liquid crystal display panel in which an adhesive layer is formed by covering the surface of the vinyl-based cross-linked resin particles by attaching a resin or the like on the surface of the particle or grafting, or the vinyl-based cross-linked resin Coloring spacers for liquid crystal display plates that are colored resin particles by adding a dye or the like to the reaction system at the time of particle synthesis, or adhesive coloring for liquid crystal display plates that combines these adhesive and coloring functions Preferable examples include a spacer.

Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples. In the following, “parts by weight” may be simply referred to as “parts” for convenience.
Example 1
In a four-necked flask, 200 parts of ethanol was charged to dissolve 2 parts of polyvinylpyrrolidone, and then 6 parts of styrene and 0.1 part of azobisisobutyronitrile were added and polymerized at 70 ° C. for 24 hours with stirring. And a polystyrene resin having an average particle diameter of 1.2 μm was obtained. 10 parts of the obtained polystyrene particles were dispersed in 300 parts of a 3% polyvinyl alcohol aqueous solution using an ultrasonic disperser. Next, a mixture of 6 parts of divinylbenzene, 3 parts of methyl methacrylate, 1 part of 2-ethylhexyl acrylate and 0.5 part of benzoyl peroxide was added to this dispersion and absorbed into polystyrene particles. Polymerization was performed at 15 ° C. for 15 hours, followed by drying at 120 ° C. under reduced pressure to obtain resin particles A.

When the particle size distribution of the obtained resin particles A was measured with a particle size distribution analyzer (Coulter Multisizer, manufactured by Coulter, Inc.), the average particle size was 6.03 μm and the coefficient of variation was 3.3%.
Next, a mixed solvent of n-hexane / ethanol = 2/1 (volume ratio) was prepared, and 400 g of the resin particles A were dispersed in 1 liter of the mixed solution to prepare a dispersion.
And, using an ultrasonic disperser having an ultrasonic vibrator made of zirconia ceramics, a glass filter holder having an aperture diameter of 7.0 μm and an electric sieve (nickel type) with 1500 lines / inch is attached. The dispersion was filtered while vibrating at a frequency of 20 kHz and an amplitude of 10 mm.

At that time, classification was performed while adding a new mixed solvent of n-hexane / ethanol so as not to clog the sieve holes or to increase the particle concentration during classification. Note that the interval between the electroformed sieve and the ultrasonic transducer was set to 10 mm.
From the dispersion after classification, the resin particles are isolated by filtration, dried under reduced pressure at 70 ° C. for 4 hours in a vacuum dryer, and then crushed to obtain the vinyl-based crosslinked resin particles of Example 1 (hereinafter, vinyl-based resin). Crosslinked resin particles (1) may be referred to).
When the particle size distribution of the obtained vinyl-based crosslinked resin particles (1) was measured with a particle size distribution analyzer (Coulter Multisizer, manufactured by Coulter, Inc.), the average particle size was 5.98 μm and the coefficient of variation was 2.6%. Furthermore, the total content of n-hexane and ethanol in the obtained vinyl-based crosslinked resin particles (1) was 10 ppm.

When the electroformed sieve used for classification was observed with an optical microscope, coarse spherical particles of 8 μm or more, aggregates of particles, or amorphous particles of 10 to 30 μm were observed.
Moreover, after storing the obtained vinyl type crosslinked resin particles (1) at 30 ° C. for 3 months, again using the mixed solvent of n-hexane / ethanol (volume ratio 2/1) in the same manner as described above. Then, the particles were classified by an electric sieve while being ultrasonically dispersed. On the electroformed sieve after classification, coarse spherical particles, aggregates of particles, and irregularly shaped particles as observed after the initial classification were not observed. Therefore, it was found that the once obtained vinyl-based crosslinked resin particles (1) did not newly generate aggregate particles or coarse particles due to aggregation or fusion.

Using the vinyl-based crosslinked resin particles (1) thus obtained as a spacer for a liquid crystal display panel, a 15-inch color STN transmission type liquid crystal display panel was prepared by a conventionally known method. A liquid crystal display panel having excellent uniformity, no color unevenness, high contrast, and excellent display quality was obtained. Further, a reliability test was performed at 50 ° C. for 1000 hours, but no seizure or the like occurred.
-Comparative Example 1-
Resin particles A in Example 1 (average particle diameter 6.03 μm, coefficient of variation 3.3%) may be referred to as vinyl crosslinked resin particles in Comparative Example 1 (hereinafter referred to as comparative vinyl crosslinked resin particles (1)). ).

Using this comparative vinyl-based crosslinked resin particle (1) as a spacer for a liquid crystal display panel, a 15-inch color STN transmission type liquid crystal display panel was prepared by a conventionally known method. A liquid crystal display panel with poor display quality was produced with uneven color and reduced contrast.
-Comparative Example 2-
The vinyl-based crosslinked resin particles of Comparative Example 2 (hereinafter referred to as Comparative Vinyl-based Crosslinked Resin Particles (2)) were prepared in the same manner as in Example 1 except that an ethanol single solvent was used instead of the n-hexane / ethanol mixed solvent. May be referred to as).

When the particle size distribution of the obtained comparative vinyl-based crosslinked resin particles (2) was measured with a particle size distribution analyzer (Coulter Multisizer, manufactured by Coulter, Inc.), the average particle size was 6.01 μm and the coefficient of variation was 3.0%. . Further, the ethanol content in the obtained comparative vinyl-based crosslinked resin particles (2) was 130 ppm.
When the electroformed sieve used for classification was observed with an optical microscope, coarse spherical particles of 8 μm or more, aggregates of particles, or amorphous particles of 10 to 20 μm were observed.
Next, the comparative vinyl-based crosslinked resin particles (2) just obtained were classified again with an electric sieve while being ultrasonically dispersed in the same manner as described above using the above-mentioned ethanol alone solvent. On the electroformed sieve after classification, coarse spherical particles, particle aggregates, and irregularly shaped particles as observed in the first classification were not observed.

Further, the obtained comparative vinyl-based crosslinked resin particles (2) were stored at 30 ° C. for 3 months, and again, as described above, using an ethanol solvent while ultrasonically dispersing, using the ethanol single solvent. Classified. On the electroformed sieve after classification, as in the first classification, coarse spherical particles, particle aggregates, and irregularly shaped particles were observed again.
From the above, with the ethanol single solvent, the comparative vinyl-based crosslinked resin particles (2) once obtained newly generate aggregate particles, coarse particles, etc. by aggregation, fusion, etc., and contain resin foreign matter I knew it would be.
Using the comparative vinyl-based crosslinked resin particles (2) thus stored at 30 ° C. for 3 months as a spacer for a liquid crystal display panel, a 15-inch color STN transmissive liquid crystal display panel was prepared by a conventionally known method. However, compared to the case of using the vinyl-based crosslinked resin particles (1), the in-plane gap uniformity was inferior, and a rough feeling was observed. Further, a reliability test was performed at 50 ° C. for 1000 hours, but seizure occurred.

-Example 2-
In a four-necked flask, 200 parts of ethanol was charged to dissolve 5 parts of polyvinylpyrrolidone, and then 0.6 parts of azobisisobutyronitrile was dissolved in a comonomer mixed with 6 parts of glycidyl methacrylate and 40 parts of styrene. The solution was added and polymerized at 70 ° C. for 24 hours with stirring. After completion of the reaction, the mixture was cooled at room temperature, 0.4 part of diisopropylate ethyl acetoaluminum was added, and the mixture was stirred for 2 hours at room temperature to cause crosslinking reaction between epoxy groups. Next, the resin particles were isolated by repeating centrifugation and washing, and then dried under reduced pressure at 120 ° C. to obtain resin particles B.

When the particle size distribution of the obtained resin particles B was measured with a particle size distribution analyzer (Coulter Multisizer, manufactured by Coulter, Inc.), the average particle size was 4.36 μm and the coefficient of variation was 3.2%.
Next, a mixed solvent of n-hexane / ethanol = 1/1 (volume ratio) was prepared, and 300 g of the resin particles B were dispersed in 1 liter of the mixed solution to prepare a dispersion.
And, using an ultrasonic disperser having an ultrasonic screen made of zirconia ceramics, an glass sieve holder with an aperture diameter of 5.5 μm and an electric sieve (nickel type) with 1000 lines / inch is attached. The dispersion was filtered while vibrating at a frequency of 50 kHz and an amplitude of 15 mm.

At that time, classification was performed while adding a new mixed solvent of n-hexane / ethanol so as not to clog the sieve holes or to increase the particle concentration during classification. The interval between the electroforming screen and the ultrasonic vibrator was set to 5 mm.
From the dispersion after classification, the resin particles are isolated by filtration, dried under reduced pressure at 80 ° C. for 4 hours or more in a vacuum dryer, and then crushed to obtain the vinyl-based crosslinked resin particles of Example 2 (hereinafter, vinyl-based crosslinked). Resin particles (2) may be referred to).
The particle size distribution of the obtained vinyl-based crosslinked resin particles (2) was measured with a particle size distribution analyzer (manufactured by Coulter, Coulter Multisizer). As a result, the average particle size was 4.30 μm and the coefficient of variation was 2.5%. Furthermore, the total content of n-hexane and ethanol in the obtained vinyl-based crosslinked resin particles (2) was 8 ppm.

When the electroformed sieve used for classification was observed with an optical microscope, coarse spherical particles of 7 μm or more, aggregates of particles, or irregularly shaped particles of 10 to 30 μm were observed.
Further, after the obtained vinyl-based crosslinked resin particles (2) were stored at 30 ° C. for 3 months, the mixed solvent of n-hexane / ethanol (volume ratio 1/1) was used again in the same manner as described above. Then, the particles were classified by an electric sieve while being ultrasonically dispersed. On the electroformed sieve after classification, coarse spherical particles, aggregates of particles, and irregularly shaped particles as observed after the initial classification were not observed. Therefore, it was found that the once obtained vinyl-based crosslinked resin particles (2) do not newly generate aggregate particles or coarse particles due to aggregation or fusion.

Using the vinyl-based crosslinked resin particles (2) thus obtained as a spacer for a liquid crystal display panel, a 15-inch TFT transmission type liquid crystal display panel was prepared by a conventionally known method. As a result, a liquid crystal display panel excellent in display quality with no color unevenness and high contrast was obtained. Further, a reliability test was performed at 50 ° C. for 1000 hours, but no seizure or the like occurred.
-Comparative Example 3-
Resin particles B (average particle diameter 4.36 μm, coefficient of variation 3.2%) in Example 2 may be referred to as vinyl-based crosslinked resin particles of Comparative Example 3 (hereinafter referred to as comparative vinyl-based crosslinked resin particles (3)). ).

Using this comparative vinyl-based crosslinked resin particle (3) as a spacer for a liquid crystal display panel, a 15-inch TFT transmission type liquid crystal display panel was prepared by a conventionally known method. A liquid crystal display panel with poor display quality was produced with unevenness and reduced contrast.
-Comparative Example 4-
The vinyl-based crosslinked resin particles of Comparative Example 4 (hereinafter referred to as Comparative Vinyl-based Crosslinked Resin Particles (4)) were prepared in the same manner as in Example 2 except that an ethanol single solvent was used instead of the n-hexane / ethanol mixed solvent. May be referred to as).

When the particle size distribution of the obtained comparative vinyl-based crosslinked resin particles (4) was measured with a particle size distribution analyzer (Coulter Multisizer, manufactured by Coulter, Inc.), the average particle size was 4.32 μm and the coefficient of variation was 3.0%. . Furthermore, the content of ethanol in the obtained comparative vinyl-based crosslinked resin particles ( 4 ) was 150 ppm. When the electroformed sieve used for classification was observed with an optical microscope, coarse spherical particles of 7 μm or more, aggregates of particles, or amorphous particles of 10 to 20 μm were observed. Next, the comparative vinyl-based crosslinked resin particles (4) just obtained were classified again with an electric sieve while being ultrasonically dispersed in the same manner as described above using the single solvent of ethanol. On the electroformed sieve after classification, coarse spherical particles, particle aggregates, and irregularly shaped particles as observed in the first classification were not observed.

Further, the obtained comparative vinyl-based crosslinked resin particles (4) were stored at 30 ° C. for 3 months, and again, as described above, using an ethanol single solvent while ultrasonically dispersing, using an ethanol sieve. Classified. On the electroformed sieve after classification, as in the first classification, coarse spherical particles, particle aggregates, and irregularly shaped particles were observed again. From the above, with the ethanol single solvent, the comparative vinyl-based crosslinked resin particles ( 4 ) once obtained newly generate aggregate particles, coarse particles, etc. by aggregation, fusion, etc., and contain resin foreign matter I knew it would be. A comparative vinyl-based crosslinked resin particle (4) stored for 3 months at 30 ° C. was used as a spacer for a liquid crystal display panel, and a 15-inch TFT transmissive liquid crystal display panel was prepared by a conventionally known method. Compared with the case of using the vinyl-based crosslinked resin particles (2), the in-plane gap uniformity was inferior, and a rough feeling was observed. Further, a reliability test was performed at 50 ° C. for 1000 hours, but seizure occurred.

Effect of the invention

  According to the present invention, the vinyl-based crosslinked resin particles having a sharp particle size distribution and substantially free from foreign resin particles such as coarse particles and particle aggregates, even if they do not affect the coefficient of variation. And its uses can be provided.

Claims (7)

In the method for producing resin particles including a step of classifying and isolating particles obtained by radical polymerization of a radically polymerizable monomer containing a crosslinkable vinyl monomer in a state dispersed in a solvent, aliphatic carbonization is used as the solvent. A method for producing vinyl-based crosslinked resin particles, comprising using a solvent containing hydrogen and / or an aromatic hydrocarbon as an essential component.
The method for producing vinyl-based crosslinked resin particles according to claim 1, wherein the total content of aliphatic hydrocarbons and / or aromatic hydrocarbons contained in the solvent is 25% by volume or more.
The method for producing vinyl-based crosslinked resin particles according to claim 1 or 2, wherein the solvent is a solvent containing at least one polar solvent selected from the group consisting of alcohol, ketone, cellosolve, ether and ester.
The total content of aliphatic hydrocarbons and / or aromatic hydrocarbons contained in the solvent is 30 to 95% by volume, and the content of polar solvents contained in the solvent is 5 to 70% by volume. The manufacturing method of the vinyl type crosslinked resin particle of Claim 3.
The manufacturing method of the vinyl type crosslinked resin particle in any one of Claims 1-4 whose carbon number of the said aliphatic hydrocarbon is 4-20.
The manufacturing method of the vinyl type crosslinked resin particle in any one of Claims 1-5 which performs the process which further advances the bridge | crosslinking in crosslinked resin particle and eliminates incomplete bridge | crosslinking to the said particle | grain.
The said classification is a manufacturing method of the vinyl type crosslinked resin particle in any one of Claims 1-6 performed by an electroformed sieve.