JP2011168632A - Crosslinked polymer fine particle and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide crosslinked polymer fine particles having an average particle size of micrometer size and narrow particle size distribution, sufficiently crosslinked, and excellent in solvent resistance and heat resistance, and a method for producing the same. <P>SOLUTION: The crosslinked polymer fine particles are provided, which (α) comprise a vinyl-based copolymer including 0.5 mass% or more of a structural unit derived from a hydrolyzable silyl group-containing vinyl monomer (a) and 10 mass% or more of a structural unit derived from a hydrophobic monofunctional vinyl monomer (b) having water solubility at 20°C of 1.0 g/100 mL or less, (β) are crosslinked by the hydrolytic condensation reaction of the hydrolyzable silyl group, and (γ) have an average particle size of 0.7-8 μm. The method for producing the crosslinked polymer fine particles is also provided, in which polymer fine particles are produced by polymerizing the vinyl monomer (a) and the hydrophobic vinyl monomer (b) in the presence of a dispersion stabilizer in a hydrophilic solvent which dissolves vinyl monomers and the dispersion stabilizer but does not dissolve the vinyl-based copolymer produced, and then the crosslinked polymer fine particles are produced by performing the hydrolytic condensation reaction of at least a part of the hydrolyzable silyl groups in the vinyl-based copolymer during or after the polymerization of the vinyl monomers. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a crosslinked polymer fine particle and a method for producing the same. More specifically, the present invention relates to a crosslinked polymer fine particle having a narrow particle size distribution and a uniform micron-sized particle size, excellent in heat resistance and solvent resistance, and the crosslinked polymer fine particle as an aggregate. The present invention relates to a method for producing a product stably and with good productivity.

Micron-sized polymer fine particles are used for applications such as light diffusion, antiglare (matte), antiblocking, and spacers. Examples of the light diffusion application include a diffusion plate and a diffusion film for a liquid crystal display, an illumination device, particularly a diffusion cover for an LED illumination device.
In these applications, the polymer fine particles are often coated by being dispersed in an organic solvent or kneaded into a resin melted at a high temperature, so that high solvent resistance and heat resistance are required. Further, in the above applications, polymer fine particles having a narrower particle size distribution and a uniform size are required in order to obtain higher performance and quality.

  As a method for producing micron-sized polymer fine particles having a narrow particle size distribution, dispersion is carried out in a solvent that dissolves the vinyl monomer in the presence of a dispersion stabilizer but does not substantially dissolve the resulting polymer. Polymerization methods are known. However, the dispersion polymerization method is a polymerization method in which a polymer is precipitated from a homogenous system. When a crosslinkable vinyl monomer having two or more vinyl groups is used as a vinyl monomer, the polymer aggregates Therefore, there is a limit to the amount of a crosslinkable vinyl monomer having two or more vinyl groups, and it is possible to produce polymer fine particles having a high crosslinking density and excellent solvent resistance and heat resistance. Have difficulty.

  Micron-size, narrow particle size distribution and high cross-linking polymer fine particles can be obtained by the method of producing and classifying polymer fine particles with high cross-linking density by suspension polymerization method, non-cross-linked polymer fine particles with narrow particle size distribution. A seed swelling polymerization method is used in which a crosslinkable vinyl monomer is absorbed and swollen and then polymerized. However, these methods require a complicated manufacturing process for a long time and have a low yield, so that the polymer fine particles obtained are extremely expensive.

Also, a non-crosslinkable monomer having one vinyl group and a crosslinkable monomer having two or more vinyl groups are copolymerized using a cationic initiator in the absence of a dispersant. A method for producing crosslinked polymer fine particles is known (Patent Document 1).
However, according to this method, it is difficult to stably produce crosslinked fine particles that are sufficiently crosslinked and excellent in heat resistance and solvent resistance.

Further, after the first stage radical emulsion polymerization of an unsaturated monomer having a hydrolyzable alkoxysilyl group and another unsaturated monomer to produce a radical polymer, an unsaturated monomer having an alkoxysilyl group is further produced. There is known a method for producing an emulsion containing polymer fine particles having a core / shell structure by subjecting a monomer and other unsaturated monomer to second-stage radical emulsion polymerization (Patent Document 2).
However, when this method is used, the size of the polymer fine particles obtained is too small, 0.1 to 0.3 μm, and is suitable for applications such as light diffusion, antiglare (matte), antiblocking, and spacers (0 It is difficult to produce polymer fine particles having a size of about 7 to 8 μm, and the amount of unsaturated monomer having an alkoxysilyl group that can be introduced due to the polymerization method and particle size is small. Thus, it is difficult to obtain polymer fine particles having excellent heat resistance and solvent resistance.

Dispersion stability of ethylenically unsaturated monomer having at least one functional group selected from hydroxyl group, epoxy group, carboxyl group and alkoxysilyl group and other ethylenically unsaturated monomer such as methyl methacrylate A method of producing reactive monodisperse resin fine particles by radical polymerization in the absence of an agent is known (Patent Document 3).
However, if an attempt is made to produce polymer fine particles having an alkoxysilyl group by this method, agglomeration occurs during the polymerization, and the polymerization cannot be stably performed, and the heat resistance and resistance are sufficiently crosslinked by the hydrolysis condensation reaction of the alkoxysilyl group. Polymer fine particles having excellent solvent properties cannot be obtained.

JP 2001-278907 A JP 2002-69365 A JP 2007-191562 A

The object of the present invention is a siloxane bond by hydrolytic condensation reaction of a hydrolyzable silyl group having a micron size of about 0.7 to 8 μm suitable for applications such as light diffusion, antiglare (matte), antiblocking and spacer. It is intended to provide vinyl polymer fine particles which are sufficiently cross-linked by the formation of and have excellent properties such as heat resistance and solvent resistance, and have a narrow particle size distribution and a uniform particle size.
Furthermore, the objective of this invention is providing the manufacturing method which can manufacture the said vinyl-type polymer microparticles | fine-particles smoothly and stably with good productivity and low cost, without producing | generating an aggregate.

The present inventors have repeatedly studied to achieve the above object. As a result, at least a vinyl monomer having a hydrolyzable silyl group and a monofunctional hydrophobic vinyl monomer having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less are used as the vinyl monomer, In the presence of the dispersion stabilizer, the vinyl monomer and the dispersion stabilizer are dissolved, but the resulting vinyl copolymer is polymerized in a hydrophilic solvent to produce polymer fine particles. When at least a part of the hydrolyzable silyl group is subjected to a hydrolytic condensation reaction at the time of polymerization or after polymerization, crosslinked polymer fine particles having an average particle size of 0.7 to 8 μm and a uniform particle size are obtained. It has been found that it can be produced with a simple process, good productivity and low cost while maintaining a stable polymerization state without causing aggregation.
Furthermore, the inventors of the present invention specified a vinyl monomer having a hydrolyzable silyl group and a monofunctional hydrophobic vinyl monomer having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less. The amount of the crosslinked polymer fine particles having a narrow particle size distribution and uniform particle size, and being sufficiently crosslinked and excellent in solvent resistance and heat resistance can be more smoothly maintained while maintaining a more stable polymerization state. We found that it can be manufactured.
In addition, the present inventors have found that the crosslinked polymer fine particles obtained thereby are sufficiently cross-linked and have excellent properties such as heat resistance and solvent resistance. It has been found that it can be used effectively in applications such as light diffusion, anti-glare (matte), anti-blocking, and spacers, because of its excellent properties, dispersibility in other polymers, and dispersibility in organic solvents. The present invention has been completed.

That is, the present invention
(1) Crosslinked polymer fine particles characterized by satisfying the following requirements (α) to (γ).
(Α) Monofunctional having a structural unit derived from a vinyl monomer having a hydrolyzable silyl group at a ratio of 0.5% by mass or more and having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less Crosslinked polymer fine particles made of a vinyl copolymer having a structural unit derived from a hydrophobic vinyl monomer in a proportion of 10% by mass or more;
(Β) cross-linked by a hydrolytic condensation reaction of a hydrolyzable silyl group of the vinyl-based copolymer; and
(Γ) The average particle size is 0.7 to 8 μm.

Furthermore, the present invention provides
(2) The crosslinked polymer fine particles according to (1), wherein the coefficient of variation (Cv) in particle size is 20% or less;
It is.

And this invention,
(3) Based on the total mass of the vinyl monomer, a vinyl monomer having a hydrolyzable silyl group is used at a ratio of 0.5% by mass or more, and the solubility in water at 20 ° C. is 1.0 g / A monofunctional hydrophobic vinyl monomer of 100 ml or less is used in a proportion of 10% by mass or more, and the vinyl monomer and the dispersion stabilizer are dissolved in the presence of the dispersion stabilizer. Polymer fine particles comprising a vinyl copolymer are produced by polymerization in a hydrophilic solvent that does not dissolve the polymer, and at least hydrolyzable silyl groups in the vinyl copolymer are produced during or after the polymerization of the vinyl monomer. 2. The method for producing fine crosslinked polymer particles according to claim 1, wherein a part thereof is crosslinked by hydrolysis condensation reaction.

Furthermore, the present invention provides
(4) The method for producing crosslinked polymer fine particles according to (3), wherein at least one of a polymer having a carboxyl group and a vinyl group and polyvinylpyrrolidone is used as a dispersion stabilizer;
It is.

The crosslinked polymer fine particles of the present invention have an average particle size of 0.7 to 8 μm, a narrow particle size distribution and a uniform particle size, are sufficiently crosslinked by siloxane bonds, and have a solvent resistance. Excellent heat resistance.
Therefore, the crosslinked polymer fine particles of the present invention can be effectively used for applications such as light diffusion, anti-glare (matte), anti-blocking, and spacer, taking advantage of the above-described properties.
In the case of the production method of the present invention, the crosslinked polymer fine particles of the present invention having the above-described excellent characteristics are stable and simple in a simple process and with high productivity without by-producting aggregates during polymerization. It can be manufactured smoothly at low cost.

FIG. 1 is a photograph taken of a cross-linked polymer fine particle (P-1) obtained in Example 1 of the present invention using a field emission scanning electron microscope (FE-SEM). FIG. 2 is a photograph of the crosslinked polymer fine particles (P-10) obtained in Example 10 of the present invention, taken using a field emission scanning electron microscope (FE-SEM).

The present invention is described in detail below.
(I) Explanation relating to crosslinked polymer fine particles :
The crosslinked polymer fine particles of the present invention have the following requirements (α) to (γ), that is,
(Α) Monofunctional having a structural unit derived from a vinyl monomer having a hydrolyzable silyl group at a ratio of 0.5% by mass or more and having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less Crosslinked polymer fine particles made of a vinyl copolymer having a structural unit derived from a hydrophobic vinyl monomer in a proportion of 10% by mass or more;
(Β) cross-linked by a hydrolytic condensation reaction of a hydrolyzable silyl group of the vinyl-based copolymer; and
(Γ) the average particle size is 0.7-8 μm;
The crosslinked polymer fine particles satisfy the requirements (α) to (γ).

  The crosslinked polymer fine particle of the present invention comprises a structural unit derived from a vinyl monomer having a hydrolyzable silyl group (hereinafter sometimes referred to as “hydrolyzable silyl group-containing vinyl monomer (a)”). A monofunctional hydrophobic vinyl monomer having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less [hereinafter referred to as “monofunctional hydrophobic vinyl monomer (b)” or simply “hydrophobic vinyl monomer It is necessary that the polymer be a crosslinked polymer fine particle formed from a vinyl copolymer having a structural unit derived from “sometimes referred to as“ mer (b) ””.

  Hydrolytic condensation of hydrolyzable silyl groups by having a structural unit derived from the hydrolyzable silyl group-containing vinyl monomer (a) in the vinyl copolymer forming the crosslinked polymer fine particles The polymer fine particles are crosslinked by the reaction, and the crosslinked polymer fine particles of the present invention having excellent heat resistance, solvent resistance and particle strength are obtained.

As the hydrolyzable silyl group-containing vinyl monomer (a), any vinyl monomer having one or more hydrolyzable silyl groups can be used, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyl Vinylsilanes such as methyldimethoxysilane and vinyldimethylmethoxysilane; silyl group-containing acrylic esters such as trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, and methyldimethoxysilylpropyl acrylate; trimethoxysilylpropyl methacrylate , Silyl group-containing methacrylates such as triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, dimethylmethoxysilylpropyl methacrylate; Silyl group-containing vinyl ethers; and the like can be illustrated silyl group-containing vinyl esters such as trimethoxysilyl down vinyl decanoate, may be used alone or two or more thereof.
Among them, as the vinyl monomer having a hydrolyzable silyl group, a hydrolyzable silyl group-containing acrylic acid ester and a hydrolyzable silyl group-containing methacrylate ester are preferably used. In particular, since it is excellent in copolymerization and the hydrolysis condensation reaction is easy to control, the polymerization can be performed smoothly and fine particles having a high degree of crosslinking can be obtained. Therefore, trimethoxysilylpropyl methacrylate (ie, trimethoxy) is obtained. Silylpropyl methacrylate), triethoxysilylpropyl methacrylate (that is, triethoxysilylpropyl methacrylate) and the like are more preferably used.

  In the crosslinked polymer fine particle of the present invention, the hydrolyzable silyl group in the vinyl copolymer forming the crosslinked polymer fine particle is obtained from the viewpoint that the heat resistance, solvent resistance, particle strength and the like of the crosslinked polymer fine particle are improved. The content ratio of the structural unit derived from the containing vinyl monomer (a) is 0.5% by mass or more based on the total mass of all monomers used in the production of the vinyl copolymer, It is preferably 5 to 90% by mass, more preferably 1 to 70% by mass, further preferably 2 to 60% by mass, and further preferably 5 to 40% by mass.

Further, the vinyl copolymer forming the crosslinked polymer fine particles of the present invention has a monofunctional monofunctional functional group having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less and one polymerizable vinyl group in the molecule. By having a structural unit derived from the hydrophobic vinyl monomer (b), the polymerization can be carried out smoothly without producing an aggregate during the polymerization for producing the polymer fine particles, and can be obtained. The water resistance of the crosslinked polymer fine particles is improved, and the dispersibility in other polymers and the dispersibility in an organic solvent is improved.
When the crosslinked polymer fine particles do not have a structural unit derived from a monofunctional hydrophobic vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less, polymer fine particles are produced. Aggregates are formed during the polymerization to prevent the polymerization from proceeding smoothly, and the resulting crosslinked polymer fine particles tend to have insufficient water resistance or poor dispersibility in resins or organic solvents.
Here, the solubility of the vinyl monomer in water at 20 ° C. in this specification is the same as that after putting equal volumes of ion-exchanged water and vinyl monomer into a glass container and stirring at 20 ° C. for 24 hours. The aqueous phase separated after standing at 5 ° C. for 5 hours is taken out with care so as not to entrain the oil phase (vinyl monomer phase), and by means of GC measurement or LC measurement, It can be determined by quantitative analysis of the monomer concentration. For GC or LC measurement selection and measurement conditions, an appropriate method is appropriately selected according to the molecular weight (boiling point) and polarity of the vinyl monomer. For example, methyl methacrylate and isobutyl methacrylate can be measured under the GC measurement conditions described in the following examples.

The monofunctional hydrophobic vinyl monomer (b) has a solubility in water at 20 ° C. of 1.0 g / 100 ml or less and can be copolymerized with a hydrolyzable silyl group-containing vinyl monomer (a). Any vinyl monomer can be used. As the monofunctional hydrophobic vinyl monomer (b), a monofunctional hydrophobic vinyl monomer having a solubility in water at 20 ° C. of 0.3 g / 100 ml or less is preferably used. A monofunctional hydrophobic vinyl monomer having a solubility of 0.1 g / 100 ml or less is more preferably used.
Examples of the hydrophobic vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less include alkyl esters, perfluoroalkyl esters, perfluoroalkyl esters, cycloalkyl esters, cyclohexanes of methacrylic acid having 2 or more carbon atoms. Alkenyl ester, benzyl ester; alkyl ester having 4 or more carbon atoms of acrylic acid, perfluoroalkyl ester, cycloalkyl ester, cycloalkenyl ester; styrene monomer such as styrene, α-methylstyrene; ethylene, propylene, isobutylene, etc. These olefins can be mentioned, and one or more of these can be used.

Among them, as the hydrophobic vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less, alkyl ester, perfluoroalkyl ester, cycloalkyl ester of methacrylic acid having 4 or more carbon atoms, Cycloalkenyl esters, acrylic acid alkyl esters having 6 or more carbon atoms, perfluoroalkyl esters, cycloalkyl esters, cycloalkenyl esters; styrene monomers such as styrene and α-methylstyrene are preferably used. Specific examples include n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methacryl Decyl acid, perfluoroalkyl ester of methacrylic acid in which all hydrogen atoms of alkyl ester group of methacrylic acid are substituted by fluorine atom, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentamethacrylate Methacrylic acid esters such as nyl; n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, decyl acrylate, as described above Acrylic acid such as perfluoroalkyl ester of acrylic acid, cyclohexyl acrylate, isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentanyl acrylate, etc., in which all hydrogen atoms of alkyl ester group of crylic acid are replaced by fluorine atoms Examples of esters include styrene and α-methylstyrene.
Among the above, as the hydrophobic vinyl monomer (b), one or more of n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, and styrene are included. , Which is preferably used from the viewpoint that the polymerization can be smoothly performed without generating an aggregate during the polymerization, and that crosslinked polymer fine particles having a narrow particle size distribution can be obtained, and in particular, n-butyl methacrylate, methacrylic acid Isobutyl and tert-butyl methacrylate are more preferably used from the viewpoint of obtaining crosslinked polymer fine particles having particularly good stability during polymerization and a narrow particle size distribution.

  In the crosslinked polymer fine particles of the present invention, the formation of aggregates during polymerization is reduced, the crosslinked polymer fine particles having a narrow particle size distribution and a uniform particle size are obtained, and the water resistance of the obtained crosslinked polymer fine particles is further improved. Derived from the hydrophobic vinyl monomer (b) in the vinyl copolymer forming the crosslinked polymer fine particles from the viewpoint of better dispersibility in other polymers and better dispersibility in organic solvents. The content ratio of the structural unit is 10% by mass or more, preferably 10-99.5% by mass, based on the total mass of all monomers used in the production of the vinyl copolymer, More preferably, it is -99 mass%, It is still more preferable that it is 30-90 mass%, It is much more preferable that it is 30-85 mass%.

The crosslinked polymer fine particles of the present invention may contain a structural unit derived from the hydrolyzable silyl group-containing vinyl monomer (a) and a structural unit derived from the hydrophobic vinyl monomer (b), if necessary. You may have the structural unit derived from the 1 type (s) or 2 or more types of the other vinyl monomer larger than 1.0 g / 100 ml in the solubility in water of ° C.
Other vinyl monomers include monofunctional vinyl monomers having a solubility in water at 20 ° C. of 3 g / 100 ml or less and greater than 1.0 g / 100 ml and having one polymerizable vinyl group in the molecule. Body [hereinafter sometimes referred to as “vinyl monomer (c)”] and monofunctional having a solubility in water at 20 ° C. of greater than 3 g / 100 ml and having one polymerizable vinyl group in the molecule And the vinyl monomer (hereinafter sometimes referred to as “vinyl monomer (d)”).
Specific examples of the vinyl monomer (c) having a solubility in water at 20 ° C. of 3 g / 100 ml or less and greater than 1.0 g / 100 ml include methyl methacrylate, ethyl acrylate, n-propyl acrylate, acrylic Examples include isopropyl acid, glycidyl methacrylate, and vinyl acetate.
Specific examples of the vinyl monomer (d) having a solubility in water at 20 ° C. of more than 3 g / 100 ml include methyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, acrylic acid 2 -Hydroxybutyl, 4-hydroxybutyl acrylate, polyethylene glycol monoacrylate, acrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, polyethylene glycol mono Methacrylate, methacrylic acid, acrylamide, acrylonitrile, vinylpyrrolidone, acryloylmorpholine, N-methylolacrylamide, N-methoxymethylacrylamide, N, N-dimethylacrylamide, N-isopropyl Acrylamide, N, N-dimethylaminopropyl (meth) acrylamide and salts thereof, N, N-dimethylaminoethyl (meth) acrylate and salts thereof, 2-acrylamido-2-methylpropanesulfonic acid and salts thereof, p-styrene Examples thereof include sulfonic acid and its salt.

The vinyl copolymer forming the crosslinked polymer fine particles of the present invention is a hydrophobic vinyl monomer having a hydrolyzable silyl group-containing vinyl monomer (a) and a solubility in water at 20 ° C. of 1.0 g / 100 ml or less. When it has a structural unit derived from the vinyl monomer (c) having a solubility in water at 20 ° C. of 3 g / 100 ml or less and greater than 1.0 g / 100 ml together with the monomer (b) Prevention of aggregate formation, production of crosslinked polymer fine particles with a narrow particle size distribution, solvent resistance, water resistance of the resulting crosslinked polymer fine particles, dispersibility in other polymers and organic solvents From the viewpoint of dispersibility, the total content of all monomers used in the production of the vinyl-based copolymer in which the content ratio of the structural unit derived from the vinyl monomer (c) forms the crosslinked polymer fine particles Is 90% by mass or less based on Preferred, more preferably 80 wt% or less, still more preferably less than 70 wt%, even more preferably at most 50 mass%.
When the vinyl monomer (c) is used in combination, methyl methacrylate, ethyl acrylate, etc. are used as the vinyl monomer (c) to prevent the formation of aggregates during polymerization and to form a crosslinked polymer having a narrow particle size distribution. It is particularly preferably used from the viewpoint of production of coalesced fine particles.

  The vinyl copolymer forming the crosslinked polymer fine particles of the present invention is a hydrophobic vinyl monomer having a hydrolyzable silyl group-containing vinyl monomer (a) and a solubility in water at 20 ° C. of 1.0 g / 100 ml or less. In the case of having a structural unit derived from the vinyl monomer (d) having a solubility in water at 20 ° C. larger than 3 g / 100 ml together with the monomer (b), preventing formation of aggregates during polymerization, From the viewpoint of water resistance, alkali resistance, acid resistance, etc. of the resulting crosslinked polymer fine particles, the content ratio of the structural unit derived from the vinyl monomer (d) is such that the vinyl copolymer forming the crosslinked polymer fine particles Based on the total mass of all monomers used for production, it is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less. When the content ratio of the structural unit derived from the vinyl monomer (d) exceeds 20% by mass, aggregates are likely to be generated during polymerization, the particle size distribution is likely to be widened, and the water resistance and resistance of the crosslinked polymer fine particles are increased. Alkalinity and acid resistance decrease.

In order to adjust the crosslinking density, the crosslinked polymer fine particle of the present invention has a structural unit derived from a polyfunctional vinyl monomer having two or more ethylenically unsaturated bonds in one molecule, if necessary. You may do it. Specific examples of the polyfunctional vinyl monomer include divinylbenzene, allyl (meth) acrylate, methylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexane. Diol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, glycerin tri (meth) ) Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, etc., and a structural unit derived from one or more of these. It is possible to have. Among these, it is preferable to use allyl (meth) acrylate together when a polyfunctional vinyl monomer is used because it is easy to suppress aggregation between the polymer fine particles during dispersion polymerization.
The amount of the polyfunctional vinyl monomer described above is preferably 10% by mass or less, preferably 5% by mass or less, based on the total mass of all monomers used for the production of the crosslinked polymer fine particles. Is more preferable. When the amount of the monofunctional vinyl monomer used exceeds 10% by mass, aggregates are likely to be generated during polymerization.

The crosslinked polymer fine particles of the present invention are crosslinked by a hydrolytic condensation reaction of hydrolyzable silyl groups in the vinyl copolymer forming the crosslinked polymer fine particles. That is, in the crosslinked polymer fine particle of the present invention, the hydrolyzable silyl group in the vinyl copolymer forming the crosslinked polymer fine particle is hydrolyzed to become a silanol group, and a dehydration condensation reaction between a plurality of silanol groups, or Crosslinking is achieved by a siloxane bond formed by dealcoholization condensation of a silanol group and an alkoxysilyl group.
The crosslinked polymer fine particles of the present invention are excellent in heat resistance and solvent resistance because they are crosslinked by hydrolysis condensation reaction (dehydration, dealcohol condensation reaction) of hydrolyzable silyl groups.
The hydrolysis condensation reaction of the hydrolyzable silyl group may be carried out with all of the hydrolyzable silyl groups contained in the vinyl copolymer forming the crosslinked polymer fine particles, or the hydrolyzable silyl group. It may be performed in a part of. In general, 10% or more, particularly 30% or more of the hydrolyzable silyl group of the vinyl-based copolymer forming the crosslinked polymer fine particles is involved in the hydrolysis condensation reaction. It is preferable from the viewpoint that the heat resistance and solvent resistance of the crosslinked polymer fine particles are improved.

The crosslinked polymer fine particles of the present invention have an average particle diameter of 0.7 to 8.0 μm.
The preferred average particle size varies depending on the application, etc., but when used as a diffusing agent for a diffusion plate of a liquid crystal display or a lighting device, it is generally preferred that the average particle size is 0.9 to 3.0 μm. When used as an AG) agent, it is generally preferred that the average particle size is 1.0 to 4.0 μm.
Here, the average particle diameter of the crosslinked polymer fine particles referred to in this specification refers to the number average particle diameter (dn). The average particle diameter [number average particle diameter (dn)] is a number average particle diameter (dn) calculated based on a particle image obtained by photographing polymer fine particles using a scanning electron microscope. The calculation method is as described in the following examples.

The crosslinked polymer fine particles of the present invention preferably have a narrower particle size distribution and a uniform particle size. In view of this, the crosslinked polymer fine particles of the present invention preferably have a particle size variation coefficient (Cv) of 20% or less, more preferably 10% or less.
As used herein, “particle size variation coefficient (Cv)” refers to a particle size variation coefficient (Cv) determined by the method described in the following examples.

The crosslinked polymer fine particles of the present invention may contain various additives as necessary. Additives include antioxidants (phenolic, sulfur, phosphorus, etc.), light stabilizers (benzotriazole, benzophenone, hindered amine, etc.), lubricants (hydrocarbons, fatty acids, higher alcohols, fats) Group amides, metal soaps, etc.), antistatic agents, fluorescent brighteners, metals such as cobalt, iron, aluminum and their alloys, fine metal oxide powders such as iron oxide, copper oxide, nickel oxide, Carbon black nigrosine dyes, pigments and dyes such as aniline blue, higher alcohol sulfate esters, alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters and other anionic surfactants, fatty acid amide derivatives, polyhydric alcohols Nonionic surfactants such as derivatives can be mentioned.
In particular, when the crosslinked polymer fine particles of the present invention are used as a diffusion plate or an antiblocking agent and added to a thermoplastic resin and melt kneaded, a stabilizer such as an antioxidant should be added to the crosslinked polymer fine particles. Is preferred. It is preferable to add a stabilizer such as an antioxidant before drying the crosslinked polymer fine particles obtained by polymerization and crosslinking treatment, particularly at a stage where the crosslinked polymer fine particles are dispersed in the polymerization solvent.

  The crosslinked polymer fine particles of the present invention have a particle size of micron size, a narrow particle size distribution and a uniform particle size, are monodispersed and have no aggregation between particles, and are crosslinked and heat resistant. Because it is also excellent in chemical resistance, strength, etc., taking advantage of these properties, light diffusion agents such as spacers for liquid crystal displays, light diffusion films for liquid crystal displays, diffusion plates, conductive fine particles, column fillers, It can be suitably used for various applications including a carrier for diagnostic agents.

(II) Explanation concerning production method of crosslinked polymer fine particles :
In the production of the crosslinked polymer fine particles of the present invention, the vinyl monomer (a) having a hydrolyzable silyl group is selected based on the total mass of all vinyl monomers used in the production of the vinyl copolymer. The presence of a dispersion stabilizer using a monofunctional hydrophobic vinyl monomer (b) having a solubility in water of 0.5% by mass or more and 20 ° C. of 1.0 g / 100 ml or less in a proportion of 10% by mass or more The polymer is then polymerized in a hydrophilic solvent that dissolves the vinyl monomer and the dispersion stabilizer but does not dissolve the vinyl copolymer that is produced. The production method of the present invention is preferably employed in which at least a part of the hydrolyzable silyl group in the vinyl copolymer is subjected to a hydrolytic condensation reaction during or after polymerization of the monomer to produce crosslinked polymer fine particles.

In the above production method, a hydrophilic organic solvent (a hydrophilic organic solvent not containing water) may be used as the hydrophilic solvent, or a mixed solvent of a hydrophilic organic solvent and water is used. Also good. At that time, as the hydrophilic organic solvent, an organic solvent having a solubility in water at 20 ° C. of 5 g / 100 ml or more is preferably used.
Specific examples of the hydrophilic organic solvent described above include monoalcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, and tetrahydrofurfuryl alcohol; Polyhydric alcohols such as ethylene glycol, glycerin, diethylene glycol; ether alcohols such as methyl cellosolve, cellosolve, isopropylpyro cellosolve, butyl cellosolve, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether; Ketones such as acetone and methyl ethyl ketone; S such as methyl acetate and ethyl acetate Ethers such as tetrahydrofuran; le such dimethylformamide, dimethyl sulfoxide and the like. Only one type of hydrophilic organic solvent may be used, or two or more types may be used in combination.
An appropriate hydrophilic organic solvent is selected from the hydrophilic organic solvents described above according to the type of vinyl monomer used for polymerization, the type of vinyl monomer to be generated, and the like.

Among them, as the hydrophilic solvent, a mixed solvent containing water and alcohol is preferably used, and in particular, a mixed solvent in which water and one or more of lower alcohols such as methanol, ethanol and isopropyl alcohol are mixed. Is more preferably used.
When a mixed solvent in which water and the above-mentioned alcohol are mixed is used as the hydrophilic solvent, the fine polymer particles produced by adjusting the mixing ratio of water and alcohol according to the type and composition of the vinyl monomer The particle size, particle size distribution, molecular weight, and the like of the particles can be easily controlled, the danger of ignition, explosion, etc. can be reduced, and the load on the environment is small.
In particular, as a hydrophilic solvent, when using a mixed solvent of water and methanol, and among them, a mixed solvent having a water: methanol mass ratio of 5:95 to 50:50, more preferably 10:90 to 40:60, This is more preferable because polymer fine particles having an average particle diameter in the target range and a narrow particle size distribution can be produced smoothly.

  The pH of the polymerization system is preferably in the range of 4 to 10.5, more preferably in the range of 5 to 10, and still more preferably in the range of 5.5 to 9.5. When the pH of the polymerization system is lower than 4 or higher than 10.5, the condensation reaction of the hydrolyzable silyl group becomes too fast, and the condensation reaction proceeds excessively during the polymerization process, and aggregates are formed. There is a case.

The above-mentioned crosslinked polymer fine particles may be produced as necessary by replacing a part of the hydrophilic solvent with a hydrophobic solvent having a solubility in water at 20 ° C. of less than 5 g / 100 ml. As the hydrophobic solvent, for example, methyl isobutyl ketone, toluene, cyclohexane and the like can be used.
In this case, the proportion of the hydrophobic solvent is preferably 30% by mass or less, more preferably 15% by mass or less, and more preferably 5% by mass or less with respect to the total amount of the solvent used for the polymerization. Further preferred. When the proportion of the hydrophobic solvent exceeds 30% by mass, the particle size distribution of the polymer particles to be produced may be broadened or aggregates may be produced during the polymerization.

  Hydrolyzable silyl group-containing vinyl monomer (a) used for the production of crosslinked polymer fine particles and monofunctional hydrophobic vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less Is one or more of the hydrolyzable silyl group-containing vinyl monomers (a) described in (I) above (in the description of the crosslinked polymer fine particles), and (I) (crosslinked polymer). 1 type or 2 types or more of monofunctional hydrophobic vinyl monomers (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less as described in the section of the description relating to the fine particles) may be used. it can.

  The use ratio of the hydrolyzable silyl group-containing vinyl monomer (a) is the above (from the point that the heat resistance, solvent resistance, particle strength, narrowness of the particle size distribution, etc. of the crosslinked polymer fine particles become better. As described in I), 0 is based on the total mass of all monomers used for the production of the crosslinked polymer fine particles (all monomers used for the production of the vinyl copolymer forming the crosslinked polymer fine particles). 0.5 mass% or more, preferably 0.5 to 90 mass%, more preferably 1 to 70 mass%, further preferably 2 to 60 mass%, and 5 to 40 mass%. It is more preferable that

  The proportion of the hydrophobic vinyl monomer (b) used is that the formation of aggregates during polymerization is reduced, the crosslinked polymer fine particles having a narrow particle size distribution and uniform particle size are obtained, and the obtained crosslinked polymer. Since the water resistance of the fine particles is improved and the dispersibility in other polymers and the dispersibility in an organic solvent is improved, as described in the above (I), all the polymers used for the production of the crosslinked polymer fine particles are used. Based on the total mass of the monomers, it is 10% by mass or more, preferably 10-99.5% by mass, more preferably 20-99% by mass, and 30-90% by mass. Is more preferable, and it is still more preferable that it is 30-85 mass%.

In the production of the crosslinked polymer fine particles, the hydrolyzable silyl group-containing vinyl monomer (a) and the hydrophobic vinyl monomer (b) are described in the above (I) as necessary. A vinyl monomer (c) having a solubility in water at 20 ° C. of more than 1.0 g / 100 ml and not more than 3 g / 100 ml and / or a vinyl monomer having a solubility in water at 20 ° C. of more than 3 g / 100 ml. One or more of the dimers (d) can be used in the proportions described in (I) above.
In production of the crosslinked polymer fine particles, if necessary, one kind of polyfunctional vinyl monomer having two or more ethylenically unsaturated bonds described in (I) above. Alternatively, two or more types can be used at a ratio of preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of all monomers used for the production of the crosslinked polymer fine particles. When the ratio of the polyfunctional vinyl monomer exceeds 10% by mass, aggregates are easily generated during polymerization.

The crosslinked polymer fine particle of the present invention has a hydrolyzable silyl group in the structural unit derived from the hydrolyzable silyl group-containing vinyl monomer (a) contained in the vinyl-based copolymer forming the polymer fine particle. It is produced by hydrolyzing to a silanol group and performing a dehydration condensation reaction between the silanol groups to form a siloxane bond.
The timing of the hydrolysis / condensation reaction of the hydrolyzable silyl group may be performed with the progress of the polymerization, may be performed after the polymerization, or may be performed both during and after the polymerization. In order to suppress the formation of aggregates and obtain crosslinked polymer fine particles having a narrow particle size distribution, the hydrolysis / condensation reaction of hydrolyzable silyl groups in the first half of the polymerization is suppressed as much as possible, and the latter half of the polymerization and / or after the polymerization. It is preferable to promote the hydrolysis / condensation reaction of the decomposable silyl group.
In order to suppress the hydrolysis / condensation reaction of the hydrolyzable silyl group, particularly in the first half of the polymerization, the polymerization is carried out in a hydrophilic organic solvent not containing water, or the pH is preferably 4 to 10. The polymerization is preferably carried out in a mixed solvent of hydrophilic organic solution and water in the range of 5, more preferably in the range of 5-10, and still more preferably in the range of 5.5-9.5, thereby agglomerating. Cross-linked polymer fine particles having a narrow particle size distribution can be produced while suppressing the production of products.

As a method for promoting the hydrolysis / condensation reaction of hydrolyzable silyl groups in the latter half of the polymerization or after the polymerization, an acid or an alkali compound is added as a condensation reaction catalyst when the reaction rate of the vinyl monomer exceeds a predetermined value. There is a way to do it. At that time, when the polymerization is carried out in a hydrophilic organic solvent not containing water, it is necessary to add water together with a catalyst comprising an acid or an alkali compound. When water is added during the polymerization, the particle size distribution of the crosslinked polymer fine particles may be widened. Therefore, when a hydrolytic condensation reaction of a hydrolyzable silyl group is performed in the latter half of the polymerization, the pH is preferably 4 to 10. It is preferable to carry out the polymerization reaction in a mixed solvent of hydrophilic organic solution and water in the range of 5, more preferably in the range of 5 to 10, more preferably in the range of 5.5 to 9.5.
Among acid catalysts or alkali catalysts used for conducting hydrolytic condensation reactions of hydrolyzable silyl groups, there is no formation of aggregates during the hydrolytic condensation reaction of hydrolyzable silyl groups, the condensation reaction rate is high, and condensation is performed. A low boiling point amine such as ammonia or triethylamine is preferably used, and ammonia is more preferably used because it can be easily removed from the crosslinked polymer fine particles after the reaction.

As the dispersion stabilizer used in the production of the crosslinked polymer fine particles, one or more of the vinyl monomers (d) mentioned in the above (I) having a solubility in water at 20 ° C. exceeding 3 g / 100 ml are used. One or more hydrophilic polymers such as a hydrophilic polymer obtained by polymerization, polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and polyethylene glycol can be used.
Among these hydrophilic polymers, polyvinyl pyrrolidone is preferably used because it does not produce aggregates during polymerization and polymer fine particles having a narrow particle size distribution can be obtained.
As polyvinyl pyrrolidone, those having a weight average molecular weight (Mw) of 5,000 to 500,000, particularly 10,000 to 200,000 are preferably used.
In addition, the weight average molecular weight (Mw) of the polymer in this specification is a weight average molecular weight (Mw) measured by the method described in the following Examples.
When polyvinyl pyrrolidone is used as the dispersion stabilizer, the amount used is preferably 1 to 50% by mass, more preferably 2 to 20% by mass based on the total mass of all monomers. . If the amount of polyvinylpyrrolidone used is less than 1% by mass, the stability during polymerization may be insufficient and aggregates may be generated. On the other hand, when the amount of polyvinyl pyrrolidone used exceeds 50% by mass, the particle size distribution of the produced polymer fine particles tends to be widened, and it becomes difficult to separate polyvinyl pyrrolidone from the polymer fine particles after polymerization.

In the present invention, a polymer having a carboxyl group and a vinyl group is preferably used in addition to the above-described polyvinyl pyrrolidone and other water-soluble polymers as a dispersion stabilizer during the polymerization reaction for producing the crosslinked polymer fine particles. . By using a polymer having a carboxyl group and a vinyl group as a dispersion stabilizer, it is possible to obtain crosslinked polymer fine particles having extremely high stability during polymerization and having a narrow particle size distribution and a uniform particle size.
The dispersion stabilizer comprising a polymer having a carboxyl group and a vinyl group is more preferably used by neutralizing a part or all of the carboxyl group with an alkali compound. The alkali compound has a low boiling point such as ammonia or triethylamine. Amines are preferably used.

Preferred examples of the polymer having a carboxyl group and a vinyl group that are preferably used as a dispersion stabilizer include:
(A) A polymer having a vinylidene-type ethylenically unsaturated group at the end of the molecular chain and a carboxyl group in the side chain (in the middle of the molecular chain) [hereinafter referred to as "polymer for dispersion stabilizer (A)"] There is sometimes]];
(B) A polymer having a vinyl group such as a (meth) acryloyl group and a carboxyl group in the side chain (in the middle of the molecular chain) [hereinafter sometimes referred to as “polymer for dispersion stabilizer (B)”];
(C) a polymer having a vinyl group such as a (meth) acryloyl group at the end of the molecular chain and a carboxyl group in the side chain (in the middle of the molecular chain) [hereinafter referred to as “polymer for dispersion stabilizer (C) Is sometimes referred to]];
Can be mentioned.

The above dispersion stabilizer polymer (A) having a vinylidene-type ethylenically unsaturated group at the end of the molecular chain and a carboxyl group in the side chain (in the middle of the molecular chain) is a vinyl monomer having a carboxyl group. It can be produced by radical polymerization of a vinyl monomer containing at least a body at a high temperature of 180 ° C. or higher. By the radical polymerization under high temperature conditions, a vinylidene type ethylenically unsaturated bond is introduced into the molecular terminal of the obtained polymer.
The weight average molecular weight of the dispersion stabilizer polymer (A) is preferably 1,000 to 200,000, more preferably 3,000 to 100,000, and 5,000 to 50,000. More preferably it is.
The acid value of the dispersion stabilizer polymer (A) [number of carboxyl groups per gram of the dispersion stabilizer polymer (A)] is preferably 0.1 to 12 meq / g. More preferably, it is 5-10 meq / g, and it is still more preferable that it is 1.0-5.0 meq / g.

The dispersion stabilizer polymer (A) is preferably used as a dispersion stabilizer when producing crosslinked polymer fine particles having a relatively large particle size (usually, crosslinked polymer fine particles having an average particle size of 1.5 to 8 μm). Used.
In producing the crosslinked polymer fine particles using the dispersion stabilizer polymer (A) as a dispersion stabilizer, the dispersion stabilizer is based on the total mass of all monomers used for producing the crosslinked polymer fine particles. The polymer for use (A) is preferably used in a proportion of 1 to 100% by mass, more preferably in a proportion of 2 to 70% by mass, and still more preferably in a proportion of 5 to 50% by mass.

The dispersion stabilizer polymer (B) having a vinyl group such as a (meth) acryloyl group and a carboxyl group in the side chain (in the middle of the molecular chain), for example, a vinyl monomer containing at least a vinyl monomer having a carboxyl group The polymer is radically polymerized to produce a prepolymer having a carboxyl group in the side chain, and some of the carboxyl groups introduced into the side chain of the prepolymer have a vinyl group such as an epoxy group and a (meth) acryloyl group. The compound can be produced by addition reaction.
The weight average molecular weight of the dispersion stabilizer polymer (B) is preferably 500 to 200,000, and more preferably 1,000 to 10,000.
Further, the acid value of the dispersion stabilizer polymer (B) [number of millimoles of carboxyl groups per gram of the dispersion stabilizer polymer (B)] is preferably 0.5 to 10 meq / g. It is more preferably ˜7 meq / g, and further preferably 1.5 to 5 meq / g.
Further, the f value of the dispersion stabilizer polymer (B) [average amount of introduced vinyl groups such as (meth) acryloyl groups per molecule of the dispersion stabilizer polymer (B)] is 0.2-2. 0.0 is preferable, 0.4 to 1.6 is more preferable, and 0.4 to 1.4 is still more preferable.

The polymer for dispersion stabilizer (B) is preferably used as a dispersion stabilizer when producing crosslinked polymer fine particles having a relatively small particle size (usually, crosslinked polymer fine particles having an average particle size of 0.7 to 3 μm). It is done.
In producing the crosslinked polymer fine particles using the dispersion stabilizer polymer (B) as a dispersion stabilizer, the dispersion stabilizer is based on the total mass of all monomers used for producing the crosslinked polymer fine particles. The polymer (B) for use is preferably used in a proportion of 0.2 to 10% by mass, and more preferably used in a proportion of 0.5 to 5% by mass.

The above dispersion stabilizer polymer (C) having a vinyl group such as a (meth) acryloyl group at the end of the molecular chain and a carboxyl group in the side chain (in the middle of the molecular chain) has, for example, a carboxyl group. In the presence of a chain transfer agent, a prepolymer having a carboxyl group at the molecular end and a hydroxyl group at the side chain is produced by radical polymerization of a vinyl monomer containing at least a vinyl monomer having a hydroxyl group, It can be prepared by first adding a compound having an epoxy group and a vinyl group such as a (meth) acryloyl group to the carboxyl group at the molecular end of the prepolymer, and then adding a dicarboxylic acid anhydride to the side chain hydroxyl group. it can.
The weight average molecular weight of the dispersion stabilizer polymer (C) is preferably 500 to 200,000, and more preferably 1,000 to 10,000.
The acid value of the dispersion stabilizer polymer (C) (the number of carboxyl groups per gram of the dispersion stabilizer polymer (C)) is preferably 0.5 to 4 meq / g. More preferably, it is ˜4 meq / g.

The polymer for dispersion stabilizer (C) is preferably used as a dispersion stabilizer when producing crosslinked polymer fine particles having a relatively small particle size (usually, crosslinked polymer fine particles having an average particle size of 0.7 to 3 μm). It is done.
In producing the crosslinked polymer fine particles using the dispersion stabilizer polymer (C) as a dispersion stabilizer, the dispersion stabilizer is based on the total mass of all monomers used for producing the crosslinked polymer fine particles. The polymer for use (C) is preferably used in a proportion of 0.2 to 10% by mass, and more preferably in a proportion of 0.5 to 5% by mass.

  Among the above-mentioned dispersion stabilizer polymers (A) to (C), the dispersion stabilizer polymer (B) or (C) having a vinyl group in the middle (side chain) or terminal of the molecular chain, A polymer in which the vinyl group is a (meth) acryloyl group can be used in a very small amount compared to other dispersion stabilizers, and can form agglomerates and the like, and is extremely stable and has a narrow particle size distribution. Since it is possible to produce fine particles, it is particularly preferably used as a dispersion stabilizer.

  In the production of crosslinked polymer fine particles by polymerizing vinyl monomers, the amount of the dispersion stabilizer comprising a polymer having a carboxyl group and a vinyl group is the total vinyl monomer used for the production of the crosslinked polymer fine particles. The total mass is preferably 0.2 to 10% by mass, and more preferably 0.5 to 5.0% by mass. If the amount of the dispersion stabilizer composed of a polymer having a carboxyl group and a vinyl group is too small, the stability during polymerization is reduced and the resulting polymer fine particles are likely to be aggregated. When the amount used is too large, the particle size distribution of the polymer fine particles to be produced becomes wide and the sizes are likely to be uneven.

  The amount of the hydrophilic solvent used in the production of the crosslinked polymer fine particles by polymerizing the vinyl monomer is preferably 1 to 50 times by mass with respect to the total mass of all monomers. It is more preferable that the mass is. If the amount of the hydrophilic solvent used is too small, the polymerization stability may be deteriorated, and the particle size distribution of the resulting crosslinked polymer fine particles tends to be widened. On the other hand, if the amount of the hydrophilic solvent used is too large, the crosslinking weight is reduced. The yield of the coalesced fine particles tends to decrease, and the productivity tends to deteriorate.

As a polymerization initiator when polymerizing a vinyl monomer to produce crosslinked polymer fine particles, a polymerization initiator usually used in radical polymerization can be used and is not particularly limited. Among them, a radical polymerization initiator that is soluble in a hydrophilic solvent is preferably used. Examples of the radical polymerization initiator that can be used in the present invention include t-butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, di-t-butyl peroxide, benzoyl peroxide, and lauroyl peroxide. , Organic peroxides such as orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide; azobisisobutyronitrile, azobiscyclohexacarbonitrile, azobis (2,4- Azo compounds such as dimethylvaleronitrile), 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50), 4,4′-azobis (4-cyanovaleric acid) (V-501); Persulfide compounds such as potassium persulfate, and one of these It can be used two or more kinds.
Among them, as the polymerization initiator, t-butyl peroxypivalate and azobis (2,4-dimethylvaleronitrile) are preferably used from the viewpoint that polymer fine particles having a narrow particle size distribution can be produced with high productivity.

  The amount of the polymerization initiator used is not particularly limited, and can be appropriately determined in consideration of the molecular weight of the crosslinked polymer fine particles to be produced, the decomposition temperature of the polymerization initiator to be used, and the like. In general, the polymerization initiator is preferably used in an amount of 0.1 to 40 parts by weight, and preferably in an amount of 1 to 10 parts by weight, based on a total of 100 parts by weight of all monomers. More preferred. If the amount of the polymerization initiator used is too small, the yield of the crosslinked polymer fine particles tends to be low. On the other hand, if the amount of the polymerization initiator used is too large, the polymerization rate becomes too high, making it difficult to carry out the polymerization stably.

  The polymerization temperature for producing the crosslinked polymer fine particles is preferably 40 to 80 ° C, more preferably 45 to 70 ° C. If the polymerization temperature is too low, the polymerization rate of the vinyl monomer will be low and it will be difficult to produce crosslinked polymer fine particles with good productivity. On the other hand, if the polymerization temperature is too high, aggregation of the generated crosslinked polymer fine particles will occur. And the particle size distribution of the crosslinked polymer fine particles is widened.

  In the present invention, in order to further improve the dispersion stability of the produced crosslinked polymer fine particles, to narrow the particle size distribution, to impart magnetism and conductivity to the crosslinked polymer fine particles, In order to color, other additives may be used together with the above dispersion stabilizer. Other additives include, for example, metals such as cobalt, iron, and aluminum and alloys thereof; fine powders of metal oxides composed of iron oxide, copper oxide, nickel oxide, etc .; pigments such as carbon black nigrosine dye and aniline blue , Dyes: anionic surfactants such as higher alcohol sulfates, alkylbenzene sulfonates, α-olefin sulfonates, phosphates; nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives 1 type, or 2 or more types of these can be used.

Crosslinked polymer fine particles produced by polymerization and hydrolysis condensation reaction of hydrolyzable silyl groups may be used in the form of a dispersion of the crosslinked polymer fine particles while being dispersed in a hydrophilic solvent. It may be used after being separated and recovered from.
As a method for separating and recovering the crosslinked polymer fine particles from the hydrophilic solvent, for example, a sedimentation separation method, a centrifugal separation method, a decantation method or the like can be employed, and further, washing and drying are performed as necessary. Moreover, you may dry directly using spray dryers, such as a spray dryer, an airflow dryer, etc., without isolate | separating and collect | recovering the dispersion liquid of a crosslinked polymer fine particle.

  In the case of the above-described production method, the produced polymer is deposited one after another without being dissolved in the hydrophilic solvent at the start of polymerization, but as the dispersion stabilizer, the above-mentioned polymer for dispersion stabilizer (A), ( When a dispersion stabilizer comprising a polymer having a carboxyl group and a vinyl group, such as C) and (B), is used for the production of the dispersion stabilizer (polymer for dispersion stabilizer) and crosslinked polymer fine particles. As a result of the copolymerization of the vinyl monomer, a graft polymer having a very high dispersion stabilizing effect is efficiently produced at the same time, so that more stable particles are formed at the very initial stage of the polymerization. Furthermore, in the stage where the polymerization of the vinyl monomer proceeds, the graft polymer is mainly formed on the surface of the growing particles in accordance with the speed at which the initially formed stable particles grow with the progress of the polymerization. Aggregation and generation of new particles are highly suppressed, and polymer fine particles having a very excellent monodispersibility and a narrow particle size distribution can be stably and easily produced with good reproducibility. Moreover, when a dispersion stabilizer comprising a polymer having a carboxyl group and a (meth) acryloyl group is used, smaller (more) initial stabilizing particles than when other dispersion stabilizers are used. Can be formed, and the growth can be stably advanced, so that it is possible to produce smaller crosslinked polymer fine particles having excellent monodispersibility.

EXAMPLES The present invention will be specifically described below with reference to examples and the like, but the present invention is not limited to the following examples.
In the following examples, the weight average molecular weight (Mw) and number average molecular weight (Mn) of a polymer, the addition rate of glycidyl methacrylate to a polymer having a carboxyl group (prepolymer), polymerization stability, and volume average of polymer fine particles Measurement or evaluation of particle diameter (dv), number average particle diameter (dn), coefficient of variation in particle size (Cv), by-product small particle amount, and methyl ethyl ketone resistance (solvent resistance) of crosslinked polymer fine particles are as follows. It was performed as follows.

(1) Weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer:
The molecular weight of the polymer was measured by gel permeation chromatography (GPC), and the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer were determined in terms of polystyrene.
Specifically, a polymer obtained by removing volatile components from a dispersion using “HLC-8120GPC” manufactured by Tosoh Corporation as a GPC device and using TSKgel super MP-M (four) as a column. A solution (concentration 5 mg / ml) dissolved in tetrahydrofuran was used as a sample, tetrahydrofuran was used as a developing solvent, and measurement was performed under conditions of a flow rate of 0.35 ml / min and a column temperature of 40 ° C. The measurement results were analyzed using a calibration curve prepared with standard polystyrene, and the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer in terms of polystyrene were determined.

(2) Rate of addition of glycidyl methacrylate to the polymer having a carboxyl group:
The residual amount of glycidyl methacrylate and the amount of by-products produced were measured by gas chromatography (GC) to determine the addition rate of glycidyl methacrylate to the polymer having a carboxyl group (prepolymer).
Specifically, using “GC-263-30” manufactured by Hitachi as a GC device, using an FID detector and a Zebron ZB-5 (30 m) as a column, the reaction solution was diluted with distilled water. Samples added with methyl cellosolve acetate as an internal standard substance, nitrogen gas as a carrier gas, a flow rate of 10 ml / min, and a column temperature increased from 50 ° C. to 200 ° C. at 7.5 ° C./min. And measured. From the peak areas of the internal standard substance (methyl cellosolve acetate), glycidyl methacrylate, and water adduct of glycidyl methacrylate, the amount of glycidyl methacrylate remaining unreacted and the amount of water adduct of glycidyl methacrylate were quantified. The water addition rate of glycidyl methacrylate was determined by dividing the amount of glycidyl methacrylate consumed by water addition by the total amount of glycidyl methacrylate. The addition rate of glycidyl methacrylate to a polymer having a carboxyl group (prepolymer) is calculated by subtracting the amount of glycidyl methacrylate and the amount of glycidyl methacrylate consumed by water addition from the total amount of glycidyl methacrylate. Obtained by dividing by.

(3) Evaluation of polymerization stability:
After the polymerization or the dispersion of crosslinked polymer fine particles obtained by polymerization and crosslinking reaction was taken out of the reactor, the amount of the polymer adhered to the inside of the reactor and the stirring blade was visually observed. Further, the dispersion of the crosslinked polymer fine particles taken out from the reactor was filtered through a 200-mesh polynet (aperture: 114 μm), and the amount of aggregate remaining on the polynet was visually observed. From both observation results, the polymerization stability was evaluated according to the following evaluation criteria.
[Evaluation criteria for polymerization stability]
(Double-circle): The polymer does not adhere to the inside of the reactor and the stirring blade, or the adhesion is negligible, and there is no or little residue of the aggregate on the polyethylene.
○: Adhesion of the polymer to the inside of the reactor and the stirring blade is small, and agglomerate remains on the polynet.
(Triangle | delta): The polymer adhesion to the inside of a reactor and a stirring blade is considerable, and the residue of the aggregate on a polyethylene is considerable.
X: The polymer adheres to the inside of the reactor and to the stirring blade, and agglomerates remain on the polyethylene.

(4) Volume average particle diameter (dv), number average particle diameter (dn), coefficient of variation of particle size (Cv) and by-product small particle amount of crosslinked polymer fine particles:
(I) Polymerization or cross-linked polymer fine particles recovered by removing volatile components (polymerization solvent, residual monomer, etc.) from a dispersion of cross-linked polymer fine particles obtained by polymerization or cross-linking reaction are uniformly dispersed in a predetermined organic solvent. Then, it was dropped on an aluminum plate, the organic solvent was removed at room temperature, and a photo was taken by a SEM method using a field emission scanning electron microscope (FE-SEM) [“JSM-6330F” manufactured by JEOL Ltd.]. I took a picture. At that time, as a photograph for measuring the particle diameter and the coefficient of variation, three photographs were taken at a magnification at which about 200 particles were photographed in one photograph and the photographing position was changed.
(Ii) In the SEM photograph taken in (i) above, the particle diameter (di) (area equivalent circle diameter determined from the photographed particle area) is measured for each of the polymer fine particles, and the following formula In accordance with (1), (2) and (3), the volume average particle size (dv), number average particle size (dn) and coefficient of variation (Cv) of the particle size were calculated. ni represents the number of particles having a particle diameter of di.
Volume average particle diameter (dv) = (Σnidi ³ / Σni) ^1/3 (1)
Number average particle diameter (dn) = (Σnidi / Σni) (2)
Coefficient of variation of particle size (Cv) (%) = 100σ / dn (3)
σ (standard deviation) = (Σ (di−dn) ² / Σni) ^1/2 (4)

The coefficient of variation (Cv) of the particle size means that the smaller the value (closer to zero), the narrower the particle size distribution, the uniform particle diameter, and the uniform particle size.
In the above calculation, the measurement result of cross-linked polymer fine particles of 0.3 μm or more, which enables accurate particle diameter measurement, was used.

(Iii) In the above, the amount of small particles (by-product small particles) having a particle diameter of 0.3 μm or less was evaluated according to the following evaluation criteria from the result of visual observation of SEM photographs.

[Evaluation criteria for amount of by-product small particles]
(Double-circle): There is no production | generation of by-product small particle or it is very few.
○: A small amount of by-product small particles are generated.
Δ: By-product small particles are considerably generated ×: By-product small particles are generated in a large amount.

(5) Methyl ethyl ketone resistance (solvent resistance) of the crosslinked polymer fine particles:
The crosslinked polymer fine particles were dispersed in 20 mass times methyl ethyl ketone, and then allowed to stand at 25 ° C. for 24 hours. After 24 hours, whether or not the crosslinked polymer fine particles are dissolved or swollen in methyl ethyl ketone is visually observed. The polymer is not dissolved or does not coalesce due to swelling, and can be redispersed while maintaining the particle shape. As for the fine particles, methyl ethyl ketone was removed at room temperature and photographed by the SEM method, and the SEM photograph was compared with the SEM photograph of the crosslinked polymer fine particles before this test, and the change in the particle size. Then, the shape change and the presence or absence of the eluted polymer component were examined, and methyl ethyl ketone resistance was evaluated according to the following evaluation criteria. In addition, the SEM photograph of the crosslinked polymer fine particles before conducting this test means a sample in which methanol fine particles are uniformly dispersed in methanol and then a sample from which methanol is removed at room temperature is observed.

[Evaluation criteria for methyl ethyl ketone resistance]
A: When the SEM photographs of the crosslinked polymer fine particles before and after the test were compared, the particle size and the particle morphology were hardly changed, and the good particle morphology was maintained.
○: When comparing SEM photographs of the crosslinked polymer fine particles before and after the test, some changes are observed in the particle size and particle form, but the substantially good particle form is maintained.
Δ: SEM photograph of the crosslinked polymer fine particles after the test confirms that it has a particle morphology, but there is a considerable change in the particle size and / or particle morphology, or the cross-linked polymer fine particles The polymer component eluted outside is confirmed.
X: Crosslinked polymer fine particles are dissolved in methyl ethyl ketone, or coalescence between the crosslinked polymer fine particles due to swelling is remarkable and cannot be redispersed after standing for 24 hours.

Crosslinked polymer fine particles, especially crosslinked polymer fine particles that have been sufficiently cross-linked, have no or little dissolution or form change of the cross-linked polymer fine particles when tested for resistance to methyl ethyl ketone. Few. As is clear from the following test results, the crosslinked polymer fine particles of the examples are excellent in methyl ethyl ketone resistance and can be suitably used for applications requiring solvent resistance and heat resistance.

<< Production Example 1 >> [Production of Dispersion Stabilizer Liquid (Aw-1)]
(1) A 500 ml capacity pressurized stirred tank reactor equipped with a hot oil heating device was filled with ethyl 3-ethoxypropionate. The reactor was heated to about 250 ° C., and the pressure in the reactor was set to be equal to or higher than the vapor pressure of ethyl 3-ethoxypropionate by a pressure controller.
(2) 20 parts by mass of methyl methacrylate, 55 parts by mass of cyclohexyl acrylate, 25 parts by mass of acrylic acid and 0.1 part of di-t-butyl peroxide were weighed to prepare a monomer mixture. The mass mixture was stored in the raw material tank.
(3) The monomer mixture prepared in (2) was continuously supplied from the raw material tank to the reactor while keeping the pressure in the reactor of (1) constant. At this time, the feed rate was set so that the average residence time of the monomer mixture in the reactor was 12 minutes. A reaction solution corresponding to the supply amount of the monomer mixture was continuously withdrawn from the outlet of the reactor. During the continuous supply of the monomer mixture, the temperature in the reactor was maintained at 230 ± 2 ° C. The reaction liquid extracted from the outlet of the reactor is introduced into a thin film evaporator to remove volatile components such as unreacted monomers in the reaction liquid, and has a vinylidene group at the end of the molecular chain. The polymer (A-1) which has a carboxyl group in the middle was obtained. Ninety minutes after the start of the supply of the monomer mixture, the collection of the polymer (A-1) was started from the outlet of the thin film evaporator, and was collected for 60 minutes.

(4) About the polymer (A-1) obtained by said (3), when a weight average molecular weight (Mw) and a number average molecular weight (Mn) were measured by the above-mentioned method by the above-mentioned method, a weight average molecular weight ( Mw) was 10600, and the number average molecular weight (Mn) was 3100.
Moreover, in the polymer (A-1) obtained by said (3), the terminal ethylenic unsaturated calculated from the density | concentration and number average molecular weight (Mn) of the terminal ethylenically unsaturated bond measured by < ¹ > H-NMR. The introduction rate of the bond (terminal vinylidene group) was 98%.
(5) The polymer (A-1) obtained in (3) above is pulverized into flakes, and 100 parts by mass of the pulverized polymer (A ₁ ), 260 parts by mass of water, and 25% aqueous ammonia 22.5 The polymer (A-1) was water-solubilized by adding a mass part to a glass flask with a condenser and stirring while heating in a 90 ° C. warm bath. After confirming that the polymer (A-1) was dissolved, water was added so that the solid content concentration measured from the heating residue at 155 ° C. × 30 minutes was 25% by mass, and the polymer (A− 1) aqueous solution [hereinafter referred to as "dispersion stabilizer liquid (Aw-1)"] was produced. The dispersion stabilizer liquid (Aw-1) (aqueous solution) had a pH of 8.0 at 25 ° C.

<< Production Example 2 >> [Production of Dispersion Stabilizer Liquid (Bw-1)]
(1) 200 parts by mass of ion-exchanged water is charged into a glass reactor equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen introduction pipe and a liquid feed pipe connection, and the reactor is stirred and blown with nitrogen gas The internal temperature was adjusted to 80 ° C.
(2) 36.4 parts by mass of methyl methacrylate, 36.4 parts by mass of isobutyl methacrylate, 20.0 parts by mass of methacrylic acid and 2-ethylhexyl thioglycolate 7 in a glass container equipped with a liquid feeding pipe by a metering pump .29 parts by mass was charged and stirred to prepare a monomer mixture (100 parts by mass).
(3) After confirming that the reactor internal temperature of (1) was stabilized at 80 ° C., 0.800 parts by mass of ammonium persulfate (polymerization initiator) was added to 3.00 parts by mass of ion-exchanged water in the reactor. A dissolved polymerization initiator aqueous solution was added, and after 5 minutes, supply of the monomer mixture prepared in (2) above to the reactor was started, and using a metering pump, the monomer mixture was 100 masses. Was fed to the reactor at a constant rate over 180 minutes. After completion of the supply, the reactor internal temperature was raised to 90 ° C. and maintained at 90 ° C. for 5 hours to obtain a dispersion of a polymer (B ₀ ) (prepolymer) having a carboxyl group in the middle of the molecular chain. . After a small amount of the dispersion was sampled and dried, the molecular weight was measured by GPC measurement by the method described above. As a result, the weight average molecular weight (Mw) was 4850 and the number average molecular weight (Mn) was 2800. The amount of carboxyl groups in the polymer (B ₀ ) is calculated as 2.33 meq / g from the monomer mixture composition.
(4) The temperature of the dispersion liquid of the polymer (B ₀ ) in the reactor obtained in the above (3) was adjusted to 80 ° C., the nitrogen gas blowing was changed to air blowing, and immediately triethylamine 9.39. 1 part by weight and 0.03 part by weight of methoxyhydroquinone were added. After 15 minutes, 5.07 parts by weight of glycidyl methacrylate was added, and the mixture was heated at an internal temperature of 80 ° C. for 3 hours to obtain one of carboxyl groups of the polymer (B ₀ ). Glycidyl methacrylate was added to the part to produce a dispersion containing a polymer (B-1) having a carboxyl group and a methacryloyl group in the middle of the molecular chain.

(5) The dispersion of the polymer (B-1) obtained in the above (4) was sampled and GC analysis was performed by the above method. As a result of the measurement, glycidyl methacrylate was not detected. A glycidyl methacrylate water adduct corresponding to 4% of glycidyl methacrylate was detected. From this result, the addition ratio of glycidyl methacrylate to the polymer (B ₀ ) is calculated to be 96%, and the water addition ratio is calculated to be 4%. The number average molecular weight of the polymer (P ₀₎ (Mn) and the polymer (P ₀₎ from the addition rate of the glycidyl methacrylate to the polymer (B-1) was composed per molecule (per polymer chain one), It was calculated that it had 0.96 ethylenically unsaturated groups on average [the average introduction rate (f value) of ethylenically unsaturated groups was 96%].
(6) To the dispersion of the polymer (B-1) obtained in (4) above, ion exchange water is added and the solid content concentration measured from the heating residue at 155 ° C. × 30 minutes is 30 mass. % Dispersion liquid (hereinafter referred to as “dispersion stabilizer liquid (Bw-1)”).
In addition, the average introduction | transduction rate (f value) of the ethylenically unsaturated group in the polymer (B-1) obtained by said (4) was calculated | required by the following calculations.

[Calculation of average introduction rate (f value) of ethylenically unsaturated groups]
The number of moles of 100 parts of the polymer (B ₀ ) is 100/2800 [Mn of the polymer (B ₀ )]
-5.07 parts x 0.96 of glycidyl methacrylate is added to 100 parts of the polymer (B ₀ ).
-From the molecular weight 142 of glycidyl methacrylate, the added mole number of glycidyl methacrylate is (5.07 parts x 0.96) / 142.
F value = number of moles of added glycidyl methacrylate / number of moles of polymer (B ₀ ) = (5.07 × 0.96 / 142) / (100/2800) = 0.96

<< Example 1 >> [Production of Crosslinked Polymer Fine Particles (P-1)]
(1) Dispersion stabilizer liquid (Aw-1) produced in Production Example 1 with 140 parts by mass of ion-exchanged water, 830 parts by mass of methanol, in a glass reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen introduction tube ) 40.0 parts by mass, 45.0 parts by mass of methyl methacrylate and 45.0 parts by mass of isobutyl methacrylate were charged, and the reactor internal temperature was adjusted to 55 ° C. while stirring and blowing in nitrogen gas. In consideration of the water of the dispersion stabilizer liquid (Aw-1), the mass ratio of water to methanol is 17/83.
(2) After confirming that the internal temperature of the reactor of (1) was stable at 55 ° C., 10.0 parts by mass of trimethoxysilylpropyl methacrylate was added to the reactor, and further 10 minutes later, polymerization was started. 4.0 parts by weight of an agent (Nippon Yushi Co., Ltd. “Perbutyl PV”; 70% solution of t-butyl peroxypivalate) was added to initiate polymerization, and immediately after the addition of the polymerization initiator, the reaction solution It was confirmed that turbidity occurred in the film, and it gradually became white and became milky white, thereby producing polymer fine particles. A dispersion of polymer fine particles having hydrolyzable silyl groups was obtained by maintaining the internal temperature of the reactor at 55 ° C. for 4 hours after the addition of the polymerization initiator (perbutyl PV).
(3) Subsequently, 32.9 parts by mass of 25% aqueous ammonia was added as a basic catalyst to promote crosslinking by hydrolysis / condensation reaction of the hydrolyzable silyl group, and the internal temperature of the reactor was raised to 65 ° C. The mixture was heated and held at the same temperature for 3 hours to obtain a fine particle dispersion.

(4) After cooling the fine particle dispersion obtained in the above (3), the fine particle dispersion was removed from the reactor while being filtered through a 200th polynet, and the dispersion of the crosslinked polymer fine particles (P-1) was recovered. . There was no adhesion of the polymer to the inside of the reactor or the stirring blade after the polymerization reaction liquid was extracted, and no filtration residue was observed on the 200th polynet. In the evaluation of the polymerization stability by the evaluation method described above, It was judged.
(5) The dispersion collected in (4) above is centrifuged to precipitate the crosslinked polymer fine particles (P-1), and then the supernatant is removed, and then the crosslinked polymer fine particles (P-1) are removed. ), And dried at 60 ° C. until the nonvolatile content when heated at 155 ° C. for 30 minutes reaches 98% by mass or more, and crushed after drying to obtain dried crosslinked polymer fine particles (P-1). It was.
(6) The crosslinked polymer fine particles (P-1) obtained in the above (5) are dispersed in methanol and then dried at room temperature to obtain SEM (field emission scanning electron microscope FE-SEM) [JEOL. Observation was performed using “JSM-6330F” manufactured by Co., Ltd. From the obtained SEM photograph, the number average particle size (dn) determined by the above method was 3.75 μm, and the coefficient of variation (Cv) in particle size was 3.9%. Moreover, it was confirmed from the SEM photograph that the amount of by-product small particles of 0.3 μm or less was very small.

(7) The crosslinked polymer fine particles (P-1) obtained in the above (5) were dispersed in 20 mass times methyl ethyl ketone, and then allowed to stand at 25 ° C. for 24 hours. After 24 hours, the crosslinked polymer fine particles (P-1) were precipitated in methyl ethyl ketone, but aggregation or coalescence between the particles did not occur and they could be easily redispersed. After the methyl ethyl ketone dispersion of the re-dispersed crosslinked polymer fine particles (P-1) was dried at room temperature, observation was performed using SEM in the same manner as in (6) above. The SEM image of the crosslinked polymer fine particles (P-1) is the same as the SEM image of the crosslinked polymer fine particles (P-1) obtained in (5) before being immersed in methyl ethyl ketone. The evaluated evaluation result of methyl ethyl ketone resistance was evaluated as ◎. It was confirmed that the crosslinked polymer fine particles (P-1) were fine particles having excellent solvent resistance due to the crosslinking effect.
(8) SEM photograph of (6) above [SEM photograph of crosslinked polymer fine particles (P-1) before being immersed in methyl ethyl ketone (MEK)] (magnification 5,000 times) is shown in FIG. The SEM photograph of (7) above [SEM photograph of crosslinked polymer fine particles (P-1) before being immersed in methyl ethyl ketone (MEK)] (5,000 magnifications) is shown in FIG.

<< Examples 2 to 5 >> [Production of Crosslinked Polymer Fine Particles (P-2) to (P-5)]
Except having changed into the following Table 1 the kind and quantity of the vinyl monomer used for superposition | polymerization, it carries out similarly to Example 1 and manufactured crosslinked-polymer fine particle (P-2)-(P-5), Evaluation of polymerization stability by the method described above, calculation of average particle diameter [number average particle diameter (dn)] and particle size variation coefficient (Cv) of the obtained crosslinked polymer fine particles, generation of by-product small particles Evaluation and methyl ethyl ketone resistance were evaluated.
The results are shown in Table 1 below.

<< Examples 6 and 7 >> [Production of Crosslinked Polymer Fine Particles (P-6) and (P-7)]
Except for changing the polymerization temperature to Table 1 below, the same procedure as in Example 1 was carried out to produce each of the crosslinked polymer fine particles (P-6) and (P-7). Evaluation, average particle diameter [number average particle diameter (dn)] and coefficient of variation of particle size (Cv) of the obtained crosslinked polymer fine particles, evaluation of by-product small particle generation, and evaluation of resistance to methyl ethyl ketone I did it.
The results are shown in Table 2 below.

<< Examples 8 and 9 >> [Production of Crosslinked Polymer Fine Particles (P-8) and (P-9)]
As a dispersion stabilizer, polyvinyl pyrrolidone [“K-30” manufactured by Wako Pure Chemical Industries, Ltd., weight average molecular weight (Mw) = 30,000] instead of the dispersion stabilizer liquid (Aw-1) is shown in Table 2 below. In the same manner as in Example 1 except that the composition of the following hydrophilic solvent and the kind and amount of the vinyl monomer were changed as shown in Table 2 below, crosslinked polymer fine particles (P- 8) and (P-9) were produced, respectively, and the above-described methods were used to evaluate polymerization stability, average particle diameter [number average particle diameter (dn)] and coefficient of variation of particle size of the obtained crosslinked polymer fine particles. The calculation of (Cv), the evaluation of the formation of by-product small particles, and the resistance to methyl ethyl ketone were evaluated.
The results are shown in Table 2 below.

<< Comparative Example 1 >> [Production of Crosslinked Polymer Fine Particles (Q-1)]
The vinyl monomer composition shown in Table 2 below, which does not contain a vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less, is used. Except for the changes shown in Table 2, the cross-linked polymer fine particles were produced in the same manner as in Example 1, but a large amount of aggregates were formed during the polymerization, which made stirring difficult. Canceled. Therefore, crosslinked polymer fine particles could not be obtained.
The results are shown in Table 2 below.

As can be seen from the results in Tables 1 and 2, in Examples 1 to 9, the solubility in water of hydrolyzable silyl group-containing vinyl monomer (a) and 20 ° C. is 1 as the vinyl monomer. 0.0 g / 100 ml or less of the hydrophobic vinyl monomer (b) is used at least in an amount within the range specified in the present invention to dissolve the vinyl monomer and the dispersion stabilizer in the presence of the dispersion stabilizer. , Polymerized in a hydrophilic solvent that does not dissolve the resulting vinyl copolymer to produce polymer fine particles comprising the vinyl copolymer, and hydrolyzable in the vinyl copolymer after polymerization of the vinyl monomer By hydrolyzing and condensing at least part of the silyl group, the average particle size (dn) is in the range of 0.7 to 8 μm, the particle size variation coefficient (Cv) is 20% or less, and the particle size distribution is narrow. Particle size and solvent resistance ( Crosslinked polymer microparticles of the present invention is excellent in methyl ethyl ketone resistance), good polymerization stability, the particle size is smoothly obtained while suppressing or by-product does not by-product of the following small particles 0.3 [mu] m.
On the other hand, in Comparative Example 1, the hydrolyzable silyl group-containing vinyl monomer (a) is used as the vinyl monomer, but its hydrophobicity in water at 20 ° C. is 1.0 g / 100 ml or less. By using a vinyl monomer having a solubility in water at 20 ° C. of greater than 1.0 g / 100 ml without using the polymerizable vinyl monomer (b), the polymerization stability is extremely poor, Aggregates were formed, and crosslinked polymer fine particles could not be produced.

<< Example 10 >> [Production of crosslinked polymer fine particles (P-10)]
(1) 99.6 parts by mass of ion-exchanged water, 475.6 parts by mass of methanol, and a dispersion stabilizer liquid produced in Production Example 2 in a glass reactor equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube (Bw-1) While charging 6.67 parts by mass, 0.13 parts by mass of 25% aqueous ammonia, 40.0 parts by mass of methyl methacrylate and 50.0 parts by mass of isobutyl methacrylate, stirring and blowing in nitrogen gas The reactor internal temperature was adjusted to 55 ° C. In consideration of the water of the dispersion stabilizer liquid (Bw-1), the mass ratio of water to methanol is 18/82 (25% aqueous ammonia is calculated as water).
(2) After confirming that the internal temperature of the reactor of (1) was stable at 55 ° C., 10.0 parts by mass of trimethoxysilylpropyl methacrylate was added to the reactor, and further 10 minutes later, polymerization was started. The polymerization was started by adding 2.40 parts by mass of an agent (“Perbutyl PV” manufactured by NOF Corporation; 70% solution of t-butyl peroxypivalate), and immediately after the addition of the polymerization initiator, the reaction solution It was confirmed that turbidity occurred in the film, and it gradually became white and became milky white, thereby producing polymer fine particles. A dispersion of polymer fine particles having hydrolyzable silyl groups was obtained by maintaining the internal temperature of the reactor at 55 ° C. for 4 hours after the addition of the polymerization initiator (perbutyl PV). The dispersion had a pH of 8.5.

(3) Subsequently, 32.9 parts by mass of 25% aqueous ammonia is added as a basic catalyst to promote crosslinking by condensation reaction of hydrolyzable silyl groups, and the internal temperature of the reactor is raised to 65 ° C. By maintaining the same temperature for 3 hours, a fine particle dispersion was obtained. In addition, when it hold | maintains at 65 degreeC for 2.5 hours, antioxidant ["AO-70" made by ADEKA Corporation; triethyleneglycolbis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) ) Propionate)] 1.00 parts.
(4) After cooling the fine particle dispersion obtained in (3) above, the fine particle dispersion was taken out from the reactor while being filtered through a 200th polynet, and the dispersion of the crosslinked polymer fine particles (P-10) was recovered. . There was no adhesion of the polymer to the inside of the reactor or the stirring blade after the polymerization reaction liquid was extracted, and no filtration residue was observed on the 200th polynet. In the evaluation of the polymerization stability by the evaluation method described above, It was judged.
(5) The dispersion liquid recovered in (4) above is dried at 60 ° C. until the non-volatile content when heated at 155 ° C. for 30 minutes is 98 mass% or more without performing a separation operation such as centrifugation. After being dried, it was crushed to obtain dried crosslinked polymer fine particles (P-10).

(6) The crosslinked polymer fine particles (P-10) obtained in (5) above were dispersed in methanol and then dried at room temperature, and SEM (field emission scanning electron microscope FE-SEM) [JEOL Observation was performed using “JSM-6330F” manufactured by Co., Ltd. From the SEM photograph thus obtained, the number average particle diameter (dn) determined by the above-mentioned method was 1.94 μm, and the coefficient of variation (Cv) in particle size was 2.3%. Moreover, it was confirmed from the SEM photograph that the amount of by-product small particles of 0.3 μm or less was very small. An SEM photograph of the crosslinked polymer fine particles (P-10) is shown in FIG. 2 (a) (magnification: 8,000 times).
(7) The crosslinked polymer fine particles (P-11) obtained in (5) above were dispersed in 20 mass times methyl ethyl ketone, and then allowed to stand at 25 ° C. for 24 hours. After 24 hours, the crosslinked polymer fine particles (P-10) were precipitated in methyl ethyl ketone. However, aggregation or coalescence between the particles did not occur, and they could be easily redispersed. After the methyl ethyl ketone dispersion of the re-dispersed crosslinked polymer fine particles (P-10) was dried at room temperature, it was observed using SEM in the same manner as in (6) above. The SEM image of the crosslinked polymer fine particles (P-10) is the same as the SEM image of the crosslinked polymer fine particles (P-10) obtained in (5) before being immersed in methyl ethyl ketone. The evaluated evaluation result of methyl ethyl ketone resistance was evaluated as ◎. It was confirmed that the crosslinked polymer fine particles (P-10) were fine particles having excellent solvent resistance due to the crosslinking effect. An SEM photograph of the crosslinked polymer fine particles (P-10) taken out from methyl ethyl ketone and dried is shown in FIG. 2 (b) (magnification: 8,000 times).

<< Examples 11 to 15 >> [Production of Crosslinked Polymer Fine Particles (P-11) to (P-15)]
The composition of the hydrophilic solvent used at the time of polymerization was changed to the composition shown in Table 3 below, and the type and amount of the vinyl monomer were changed to Table 3 below (Examples 13 to 15), and Example 10 and In the same manner, crosslinked polymer fine particles (P-11) to (P-15) were produced and evaluated for polymerization stability by the above-described method, and the average particle diameter of the obtained crosslinked polymer fine particles [number average particle [Diameter (dn)] and the coefficient of variation (Cv) of the particle size, the formation of by-product small particles and the resistance to methyl ethyl ketone were evaluated.
The results are shown in Table 3 below.

<< Examples 16 to 20 >> [Production of Crosslinked Polymer Fine Particles (P-16) to (P-20)]
At the time of polymerization, the amount of the dispersion stabilizer used, the composition of the hydrophilic solvent, the addition amount of 25% aqueous ammonia, the kind and amount of the vinyl monomer, and the polymerization temperature are listed in Table 4 below. Otherwise, the same procedure as in Example 10 was carried out to produce crosslinked polymer fine particles (P-16) to (P-20), and polymerization stability was evaluated and obtained by the method described above. The average particle diameter [number average particle diameter (dn)] and particle size variation coefficient (Cv) of the crosslinked polymer fine particles were calculated, the formation of by-product small particles, and the methyl ethyl ketone resistance were evaluated.
The results are shown in Table 4 below.

<< Examples 21 to 22 >> [Production of Crosslinked Polymer Fine Particles (P-21) to (P-22)]
The same procedure as in Example 10 was conducted except that the composition of the hydrophilic solvent used in the polymerization was changed to the composition shown in Table 5 below, and the type and amount of the vinyl monomer were changed to Table 5 below. Polymer fine particles (P-21) to (P-22) were produced and evaluated for polymerization stability by the method described above, and the average particle diameter [number average particle diameter (dn)] and particles of the obtained crosslinked polymer fine particles Calculation of the coefficient of variation of size (Cv), evaluation of the formation of by-product small particles, and evaluation of methyl ethyl ketone resistance were performed.
The results are shown in Table 5 below.

<< Comparative Example 2 >> [Production of Crosslinked Polymer Fine Particles (Q-2)]
As the crosslinkable monomer, allyl methacrylate was used in place of the hydrolyzable silyl group-containing vinyl monomer (a), the hydrophilic solvent composition shown in Table 5 below, and the type and amount shown in Table 6 below. In the same manner as in Example 10 except that the vinyl monomer was used, the cross-linked polymer fine particles were produced. A large amount of aggregates formed during the polymerization became difficult to stir, so the polymerization was stopped. did. Therefore, crosslinked polymer fine particles could not be obtained.

<< Comparative Example 3 >> [Production of Polymer Fine Particles (Q-3)]
Polymer fine particles (Q-3) were produced in the same manner as in Example 20 except that a vinyl monomer of the type and amount shown in Table 6 below was used without using a crosslinkable monomer. . Evaluation of polymerization stability by the method described above, calculation of average particle diameter [number average particle diameter (dn)] and particle size variation coefficient (Cv) of the obtained polymer fine particles (Q-3), small by-product Evaluation of particle formation and methyl ethyl ketone resistance were performed.
The results are shown in Table 6 below.

<< Comparative Example 4 >> [Production of Crosslinked Polymer Fine Particles (Q-4)]
As the crosslinkable monomer, allyl methacrylate is used in place of the hydrolyzable silyl group-containing vinyl monomer (a), and the types and amounts of vinyl monomers shown in Table 6 below are used. Crosslinked polymer fine particles (Q-4) were produced in the same manner as in Example 20, and the polymerization stability was evaluated by the method described above. The average particle size of the obtained crosslinked polymer fine particles [number average particle size (dn) ] And the coefficient of variation (Cv) of the particle size, evaluation of the formation of by-product small particles, and evaluation of resistance to methyl ethyl ketone.
The results are shown in Table 6 below.

<< Comparative Example 5 >> [Production of Crosslinked Polymer Fine Particles (Q-5)]
As the crosslinkable monomer, instead of the hydrolyzable silyl group-containing vinyl monomer (a), ethylene glycol dimethacrylate is used, and the types and amounts of vinyl monomers shown in Table 6 below are used. Except for the above, an attempt was made to produce crosslinked polymer fine particles in the same manner as in Example 20. As a result, a large amount of agglomerates formed during the polymerization became difficult to stir, so the polymerization was stopped. Therefore, crosslinked polymer fine particles could not be obtained.

<< Comparative Example 6 >> [Production of Crosslinked Polymer Fine Particles (Q-6)]
The amount of the monofunctional vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less is less than 10% by mass, and the vinyl monomer composition shown in Table 6 below is adopted. The hydrophilic solvent composition and polymerization temperature shown in Table 6 below were adopted, a dispersion stabilizer was not used, and the polymerization initiator was V-50 [2, 2′-, manufactured by Wako Pure Chemical Industries, Ltd. instead of perbutyl PV. 0.17 parts of azobis (2-amidinopropane) dihydrochloride] and 0.03 parts of V-70 [2,2′-azobis (4-methoxy-2,4′-dimethylvaleronitrile)] were used. Other than that, an attempt was made to produce crosslinked polymer fine particles in the same manner as in Example 10. As a result, a large amount of agglomerates were formed during the polymerization and stirring became difficult, so the polymerization was stopped. Therefore, crosslinked polymer fine particles could not be obtained.

  As can be seen from the results in Tables 3 to 6, in Examples 10 to 22, the solubility in water of hydrolyzable silyl group-containing vinyl monomer (a) and 20 ° C. is 1. A monofunctional hydrophobic vinyl monomer (b) of 0 g / 100 ml or less is used at least in an amount specified in the present invention, and the vinyl monomer and the dispersion stabilizer are dissolved in the presence of the dispersion stabilizer. Polymer fine particles made of a vinyl copolymer are produced by polymerizing in a hydrophilic solvent that does not dissolve the resulting vinyl copolymer, and hydrolyzable silyl in the vinyl copolymer is obtained after polymerization of the vinyl monomer. By hydrolyzing and condensing at least a part of the groups, the average particle size (dn) is in the range of 0.7 to 8 μm, the particle size variation coefficient (Cv) is 10% or less, and the particle size distribution is narrow. Particle size is uniform and solvent resistance (resistance The crosslinked polymer fine particles of the present invention, which is excellent in tilethyl ketone properties, have good polymerization stability and can be obtained smoothly while preventing by-production of small particles having a particle size of 0.3 μm or less or by-products. Yes.

On the other hand, in Comparative Example 2, the use of allyl methacrylate instead of the hydrolyzable silyl group-containing vinyl monomer (a) as the crosslinkable vinyl monomer greatly reduced the polymerization stability. A large amount of aggregates are generated during the polymerization, and crosslinked polymer fine particles cannot be obtained.
Further, in Comparative Example 3, the polymer fine particles obtained were greatly inferior in solvent resistance (methyl ethyl ketone resistance) because no crosslinkable vinyl monomer was used.
Further, styrene is used as the hydrophobic vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less, and a hydrolyzable silyl group-containing vinyl monomer (a In Comparative Example 4 using allyl methacrylate instead of (), the polymerization stability is poor, and the resulting crosslinked polymer fine particles are poor in solvent resistance (methyl ethyl ketone resistance).
Further, styrene is used as the hydrophobic vinyl monomer (b) having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less, and a hydrolyzable silyl group-containing vinyl monomer ( In Comparative Example 5 using ethylene glycol dimethacrylate instead of a), the polymerization stability is greatly inferior, and a large amount of aggregates are formed during the polymerization, so that crosslinked polymer fine particles cannot be obtained.
In Comparative Example 6, with reference to the contents described in Patent Document 3, no dispersion stabilizer was used, and V-50 [2,2′-azobis (2-amidinopropane) dihydrochloride]. The dispersion polymerization process was carried out using 17 parts and 0.03 part of V-70 [2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile)]. As the vinyl monomer, a hydrolyzable silyl group-containing vinyl monomer (a) was used, but a monofunctional hydrophobic vinyl monomer having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less ( Since the amount of use of b) was less than 10% by mass, the polymerization stability was greatly inferior, and a large amount of aggregates were formed during the polymerization, so that crosslinked polymer fine particles could not be obtained. That is, even if the technique of Patent Document 3 is used, it is not possible to synthesize crosslinked fine particles excellent in heat resistance and solvent resistance, which are crosslinked by a hydrolytic condensation reaction of a hydrolyzable silyl group.

  The crosslinked polymer fine particles of the present invention have an average particle size of 0.7 to 8 μm, a narrow particle size distribution and a uniform particle size, are sufficiently crosslinked by siloxane bonds, and have a solvent resistance. In addition, since it is excellent in heat resistance, it can be effectively used for applications such as light diffusion, antiglare (matte), antiblocking, spacers, etc., and has the above-described excellent properties according to the production method of the present invention. The fine polymer particles can be smoothly produced in a stable state with good productivity, low cost, and without a by-product of aggregates during polymerization.

Claims (4)

Crosslinked polymer fine particles satisfying the following requirements (α) to (γ):
(Α) Monofunctional having a structural unit derived from a vinyl monomer having a hydrolyzable silyl group at a ratio of 0.5% by mass or more and having a solubility in water at 20 ° C. of 1.0 g / 100 ml or less Crosslinked polymer fine particles made of a vinyl copolymer having a structural unit derived from a hydrophobic vinyl monomer in a proportion of 10% by mass or more;
(Β) cross-linked by a hydrolytic condensation reaction of a hydrolyzable silyl group of the vinyl-based copolymer; and
(Γ) The average particle size is 0.7 to 8 μm.   The crosslinked polymer fine particle according to claim 1, wherein the coefficient of variation (Cv) of the particle size is 20% or less.   Based on the total mass of the vinyl monomer, a vinyl monomer having a hydrolyzable silyl group is used in a proportion of 0.5% by mass or more, and the solubility in water at 20 ° C. is 1.0 g / 100 ml or less. A monofunctional hydrophobic vinyl monomer is used in a proportion of 10% by mass or more, and the vinyl monomer and the dispersion stabilizer are dissolved in the presence of the dispersion stabilizer, but the resulting vinyl copolymer is dissolved. To produce polymer fine particles comprising a vinyl copolymer by polymerization in a hydrophilic solvent, and at least part of the hydrolyzable silyl group in the vinyl copolymer during or after polymerization of the vinyl monomer. The method for producing fine crosslinked polymer particles according to claim 1, wherein the crosslinked polymer particles are crosslinked by hydrolysis condensation reaction.   The method for producing crosslinked polymer fine particles according to claim 3, wherein at least one of a polymer having a carboxyl group and a vinyl group and polyvinylpyrrolidone is used as the dispersion stabilizer.

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