JPH08217824A - Crosslinkable optical material - Google Patents

Abstract

PURPOSE: To obtain the subject material comprising a polymer produced by precipitation polymerization, useful for plastic lens, transparent plates, etc., having high mechanical strength and high refractive index and excellent in transparency, light weightness, and durability. CONSTITUTION: This optical material comprises a polymer (A1 ) produced by precipitation polymerization, e.g. a precipitation polymer composed mainly of a styrene-based monomer, and containing 1mol% or more of radical polymerizable functional group. This material is obtained, for example, by polymerizing a solution prepared by dissolving the component A1 in (B1 ) a radical polymerizable monomer soluble for the component A1 (e.g. styrene-based compound, divnylbenzene); the number-average molecular weight of the component A1 is 10 to 8000, especially 20 to 5000, the content of the component B1 in this material being 5wt.% or more, especially 10wt.% or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plastic lens,
The present invention relates to a cross-linkable optical material that is suitably used for a transparent plate or the like and has a light weight, a high refractive index, and a high durability.

[0002]

2. Description of the Related Art A crosslinkable optical material represented by a plastic lens is usually produced by cast polymerization of monomers filled in a mold.

Cast polymerization generally has two major problems. This is because the gasket due to the high permeability of the monomer and the wear of the adhesive tape used as the gasket and the low viscosity of the monomer are likely to cause liquid leakage during cast polymerization.

As a countermeasure, a method has been proposed in which an oligomer or a polymer is dissolved in a monomer to increase the viscosity of the whole monomer.

[0005]

The oligomer or polymer added to increase the viscosity of the entire monomer is usually radical polymerized separately and dissolved in the monomer.

The radical polymerization method of the oligomer or polymer includes a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method and a precipitation polymerization method. The solution polymerization method has problems that the degree of polymerization is unlikely to increase and that it is difficult to remove the solvent from the polymer. In the suspension polymerization method and emulsion polymerization method, it is difficult to remove the suspension agent and the emulsifier from the polymer,
Use as an optical material gives poor transparency results.
The bulk polymerization method has problems that residual monomers are likely to increase and that it is not suitable for small-scale production.

The present invention is intended to solve the drawbacks of the prior art, and an object thereof is to provide an optical material having high transparency, light weight, high refractive index and high strength.

[0008]

The present invention has the following constitution in order to achieve the above object.

"Crosslinkable optical material containing a polymer polymerized by a precipitation polymerization method." The precipitation polymerization method used in the present invention means a polymerizable monomer as a precursor thereof. It is a polymerization method in which the polymerizable monomer is dissolved in a solvent that dissolves but the polymer does not dissolve, and the solution is polymerized to recover a polymer having a certain degree of polymerization as a precipitate.

The polymerizable monomer used in the present invention for polymerization by the precipitation polymerization method contains a radically polymerizable monofunctional monomer, an epoxy resin and a curing agent, an isocyanate compound and an alcoholic hydroxyl group or an amino group. The polymerizable monomer preferably used in the present invention is a radically polymerizable single compound because of the ease of precipitation polymerization and the purpose of use in the present invention (optical material). It is a quantity.

Representative examples of such radically polymerizable monofunctional monomer (hereinafter referred to as monomer A) are shown below.

Alkyl (meth) acrylates such as (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth)
Acrylate, hydroxyalkyl (meth) acrylates such as hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, acrylonitrile, phenoxy (meth) acrylate, phenoxyethyl (meth) acrylate, amino such as aminoethyl (meth) acrylate Examples include alkyl (meth) acrylates, vinyl acetate, fumaric acid, fumaric anhydride, thiol methacrylate of benzyl mercaptan, methacryloxythioethylene thiomethylenebenzene, and aromatic vinyl monomers. In particular, when a styrene compound is used among the aromatic vinyl monomers, the present invention can be preferably achieved in terms of making the optical material lightweight (low specific gravity).

Examples of such styrene compounds include styrene and alkylstyrenes such as methylstyrene, ethylstyrene, propylstyrene and neopentylstyrene. Further, there are alkoxystyrenes such as methoxystyrene, butoxystyrene and isobutoxystyrene, and halogenated alkylstyrenes such as monochloromethylstyrene. There are also hydroxyalkyl styrenes such as hydroxymethyl styrene.

Further, α-methylstyrene, methyl α
-Methylstyrene, alkyl α-methylstyrenes such as ethyl α-methylstyrene, methoxy α-methylstyrene, butoxy α-methylstyrene, isobutoxy α
There are alkoxy α-methylstyrenes such as -methylstyrene and halogenated alkyl α-methylstyrenes such as monochloromethyl α-methylstyrene. There are also hydroxyalkyl α-methylstyrenes such as hydroxymethyl α-methylstyrene. These are used alone or as a mixture.

In the present invention, the aromatic vinyl monomer as described above is preferably 60 mol% or more, more preferably 7 mol% or more.
When it is 0 mol% or more, the achievement of the present invention is particularly facilitated. When the amount of the aromatic vinyl-based monomer used is less than 60 mol%, either the refractive index or the specific gravity tends to be insufficient.

The above-mentioned monomer A is dissolved in a solvent in which the monomer A is dissolved but the polymer is not dissolved, and precipitation polymerization is carried out. Representative examples of the solvent used in the present invention are shown below.

Aliphatic hydrocarbons such as hexane and octane, aromatic hydrocarbons such as benzene, toluene and xylene, alcohols such as methanol, ethanol and ethylene glycol, ethers such as ethyl ether, methyl acetate, Esters such as ethyl acetate, 2-
Methoxyethanol, acetone, dimethylsulfoxide, dimethylformamide, dimethylacetamide and the like. These are used alone or as a mixture based on the solubility of the monomer A and its polymer. Of these, water may be particularly effective as a solubility control agent in the water-soluble solvent.

The polymerization of the monomer A is carried out by dissolving the monomer A in the above-mentioned solvent and carrying out precipitation polymerization together with the radical polymerization initiator, usually under heating and stirring.

In the precipitation polymerization method, since the polymer is generally recovered as a powder, it is easy to wash and remove the solvent.
Since it is not necessary to add a dispersant or the like during the polymerization, the purity of the obtained polymer is generally high. Therefore, it is preferably used for optical material applications.

The precipitated polymer of the monomer A has a number average degree of polymerization (gel permeation chromatography (hereinafter,
A polystyrene-converted value (according to GPC)) of about 10 to about 8,000, more preferably about 20 to about 5,000, is preferable for carrying out the present invention. When the average degree of polymerization is less than 10, it is difficult to prevent the gasket, which is the original purpose of the present invention, from being worn out, liquid leakage, and deterioration of transparency of the adhesive tape used as the gasket. On the other hand, when the average degree of polymerization exceeds 8000, the rate of dissolving the precipitated polymer of the monomer A in the monomer that dissolves the monomer A used in the present invention (hereinafter referred to as the monomer B) decreases. Also, since the viscosity of the solution becomes too high, it tends to be unsuitable as a monomer for cast polymerization.

The present invention relates to a polymer of monomer A and monomer B
It is preferably achieved when the polymer is a mixture of

Examples of the monomer B include a radically polymerizable monomer, an epoxy resin and a curing agent, an isocyanate compound and a compound containing an alcoholic hydroxyl group or an amino group, and the like. Radical-polymerizable monomers are particularly preferably used in view of the solubility of the polymer and the lightness of the obtained optical material.

As the radically polymerizable monomer which is the monomer B, the one used in the monomer A can be generally used, but two radically polymerizable double bonds are included in the molecule. A compound having the above can also be preferably used. Examples of such compounds are given below.

Divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, propanediol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, trimethylolpropane di ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, di (meth) of ethylene oxide or propylene oxide added to both ends of hydroquinone or bisphenols Acrylate, (meth) acryloyloxyethyl sulfide,
1,4-bis [(meth) acryloylthioethylthiomethyl] benzene and the like.

To achieve the present invention, the monomer B contains a compound having two or more functional groups (radical-polymerizable double bonds) in an amount of 5% by weight or more, and further 10% by weight or more. Is preferred. When the amount of the compound having two or more functional groups is less than 5% by weight, the heat resistance of the obtained optical material tends to be poor.

The monomer B is preferably composed mainly of the above-mentioned styrene compound and divinylbenzene for the purpose of obtaining an optical material having a higher refractive index and a lower specific gravity. In particular, the sum of the styrene compound and divinylbenzene is 50% by weight or more of the monomer B, and further 60
The present invention is preferably achieved when the content is at least wt%.

The precipitation polymer of the monomer A used in the present invention and the monomer B must be compatible with each other.
It is particularly preferable that the and the monomer B are the same kind.

The precipitation polymer of the monomer A of the present invention is particularly suitable for achieving the present invention when it has a functional group capable of radically polymerizing with the monomer B. When the precipitation polymer of the monomer A does not have a functional group capable of copolymerizing with the monomer B, the precipitation polymer of the monomer A is soluble in the monomer B at a stage before the polymerization. Even if it is present, phase separation may occur during polymerization, resulting in a white turbid molded body.

The functional group capable of undergoing radical polymerization with the monomer B contained in the precipitation polymer of the monomer A is usually 1 mol% or more, preferably 2 mol% of the monomer constituting the precipitation polymer of the monomer A. When it is at least%, the object can be suitably achieved. In addition, mol%
Is the molar ratio of the monomer A to all the constituent monomers including the modification after the precipitation polymerization.

As a method for imparting a radically polymerizable functional group with the monomer B to the precipitation polymer of the monomer A, a method of imparting a radically polymerizable functional group as a pendant will be given below.

As a first step, when the monomer A is subjected to precipitation polymerization, a reactive group is introduced by the following method.

Method of Introducing as an End Group If polymerization is carried out using a chain transfer agent having an OH group such as mercaptoethanol, or if telomerization polymerization is carried out using a halogen-based solvent, it is determined whether an OH group is present at the end. ,
Polymers with halogen can be obtained. The terminal halogen can be easily hydrolyzed to OH.

Method of Introducing as Copolymerization Component If 2-hydroxyethyl (meth) acrylate, hydroxymethylstyrene or the like is used as a monomer to be copolymerized with the monomer A, an OH group can be introduced. An OH group can be introduced by hydrolyzing after polymerization using monochloromethylstyrene, vinyl acetate or the like. 2-
An amino group can be introduced by using aminoethyl (meth) acrylate. A carboxyl group can be introduced by using (meth) acrylic acid. If fumaric anhydride is used, an anhydrous carboxyl group can be introduced. An isocyanate group can be introduced by using methacroyl isocyanate or 2-metacryloyloxyethyl isocyanate. Epoxy groups can be introduced by using glycidyl (meth) acrylate.

The OH group and the amino group can react with the isocyanate group. Further, OH group, amino group, carboxyl group, and anhydrous carboxyl group can react with epoxy group. Furthermore, OH groups can react with carboxyl groups.

In the second step, a radically polymerizable functional group is provided as a pendant to the precipitation polymer of the monomer A by utilizing a reactive group such as an OH group. Examples of the compound used for that purpose include the following.

A. Examples of the compound having an isocyanate group include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-hydroxyethyl methacrylate and 1/1 of xylylene diisocyanate.
(Molar ratio) Reaction products and the like.

B. Examples of the compound having an epoxy group include glycidyl methacrylate and glycidyl acrylate.

C. Examples of the compound having a carboxyl group include acrylic acid and methacrylic acid.

D. Examples of the compound having an OH group include 2-hydroxyethyl (meth) acrylate, hydroxymethylstyrene and allyl alcohol.

E. As a compound having an amino group, 2-
Examples include aminoethyl (meth) acrylate.

In the present invention, the ratio of the [monomer B] / [precipitated polymer of the monomer A] to the precipitation polymer of the monomer B and the monomer A is preferably in the range of 0. When it is 2 to 20, and more preferably 0.5 to 15, the object of the present invention can be achieved particularly easily. When the ratio of [monomer B] / [precipitated polymer of monomer A] is less than 0.2, the viscosity of the monomer for cast polymerization becomes too high, and the monomer tends to be unsuitable for cast polymerization. . Also, if this ratio exceeds 20,
Permeation of the monomer into the gasket, local decrease in transparency, and liquid leakage during molding may occur.

The plastic lens of the present invention is 546.
It is preferable that the refractive index measured at a wavelength of 1 nm (e-line) is 1.55 or more and the specific gravity measured at 23 ° C. is 1.15 or less, which is acceptable for the monomer B and the monomer used in the present invention. The soluble polymer of the monomer A is preferably selected so as to fall within the above ranges of refractive index and specific gravity.

To obtain the plastic lens of the present invention,
Usually, a cast polymerization method is used. In the cast polymerization method, generally, a precipitation polymer of the monomer A and a monomer are placed in a space formed by two glass molds facing each other and a synthetic resin gasket that seals the periphery of the glass mold with a constant thickness. The composition containing B as a main component is filled and heated or photopolymerized, but is not limited thereto.

As a thermal polymerization condition, a method of gradually raising the temperature from room temperature is generally adopted, and the maximum temperature is 14
The polymerization time is about 0 ° C. and the time is about 10 to 60 hours. In the case of photopolymerization, it is general that after exposure to an actinic ray for a time on the order of seconds to minutes, after-curing by heating is performed.

It is also preferable that the plastic lens after polymerization is subjected to hard coating or antireflection coating after being released from the mold.

The plastic lens of the present invention is preferably used for optical applications such as spectacle lenses, sunglasses lenses, fashion lenses and camera lenses.

[0047]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Polymers used in Examples and Comparative Examples were prepared as follows.

Reference Example 1 As monomer A, styrene 300 g, methanol 750
g, 100 g of water in a compatible mixture of 2.0 g of potassium persulfate
Was dissolved. The mixture was heated under a nitrogen stream and stirred at 65 ° C for 30 hours. The precipitated polymer thus precipitated was collected by filtration and dried under reduced pressure to remove the residual monomer and the dispersion medium. A precipitation polymer having a polystyrene-equivalent number average degree of polymerization of 1600 by GPC was obtained. The recovered precipitated polymer was a powder and had very good handleability.

Reference Example 2 As the monomer A, 290 g of styrene, 10 g of hydroxyethyl methacrylate, 750 g of methanol, 10 parts of water
0.7 g of potassium persulfate was dissolved in 0 g of the compatible mixture. The mixture was heated under a nitrogen stream and stirred at 65 ° C for 20 hours.
The precipitated polymer thus precipitated was collected by filtration and dried under reduced pressure to remove the residual monomer and the dispersion medium. A polymer having a polystyrene reduced number average degree of polymerization of 1200 by GPC was obtained. The precipitated polymer was a powder and was very easy to handle.

Reference Example 3 16 g of azobisisobutyronitrile (AIBN) was dissolved in a mixture of 1700 g of styrene, 60 g of hydroxyethyl methacrylate and 1800 g of toluene, and solution polymerization was carried out at 85 ° C. for 20 hours under a nitrogen stream, followed by GPC. A polymer solution containing a copolymer having a polystyrene equivalent number average molecular weight of 140 was obtained.

Attempts were made to recover the solution polymer from the above polymer solution by the following various methods.

Recovery Method 1 When the polymer solution was dropped into methanol and acetone and a so-called reprecipitation treatment was performed, a good reprecipitate having a hard film was not formed, but a sticky sticky precipitate was obtained.
Therefore, it was not possible to recover the solution polymer by carrying out the subsequent operations, that is, filtration, washing and drying.

Recovery Method 2 The polymer solution was spread on a vat and dried under reduced pressure. Desolvation was successful until the solution was fluid, but as the viscosity increased, foaming began and overflowed from the container. Further, the solidification accompanying the decrease of the residual solvent reduced the desolvation rate, and it took several days until the residual solvent was reduced to the target of 1% by weight or less.

The shape of the solution polymer thus obtained was indefinite, and the handleability during storage, weighing, dissolution, etc. was poor.

Recovery Method 3 The polymer solution was placed in a kneader capable of heating under reduced pressure, and the solvent was removed while stirring. When the residual solvent was 10% by weight or less, it was fed to an extruder with a vent and collected as pellets. Since the target residual solvent was not reduced to 1% by weight or less in the one-time treatment with the extruder, a total of three repeated passage treatments were performed with the vented extruder. The solution polymer recovered in the form of pellets was subjected to a large amount of heat history at high temperatures, and thus precipitated polymers (Reference Examples 1 and 2)
Compared with, it was colored yellow and was not suitable for optical use.

Reference Example 4 100 g of styrene, 3.4 g of hydroxyethyl methacrylate, 250 g of water, 0.2% of hydrogen peroxide of 30% by weight.
g and 1 g of sodium oleate were mixed and emulsion-polymerized at 80 ° C. for 12 hours under a nitrogen stream. Hydrochloric acid was added to the produced latex to destroy the emulsified state and collect a lumpy emulsion polymer. After sprinkling and washing, it was dried. The polystyrene reduced number average molecular weight by GPC was 2000.

Reference Example 5 Styrene 57 g, hydroxyethyl methacrylate 1.
A mixture of 7 g of AIBN and 0.6 g of AIBN was used as polyvinyl alcohol (Nippon Gosei Kagaku Co., Ltd. “Gothenol”).
GL05) 3 g, sodium lauryl sulfate 0.05 g and sodium sulfate 2.5 g were dispersed in 200 g of water. While maintaining the temperature of 85 ° C., suspension polymerization was carried out under a nitrogen stream for 20 hours. After the polymerization, the suspended particles are filtered off,
It was washed and dried under reduced pressure. The polystyrene reduced number average molecular weight by GPC was 650.

Example 1 10 parts by weight of the polystyrene prepared by the precipitation polymerization method prepared in Reference Example 1 was mixed with 80 parts by weight of styrene and 10 parts by weight of commercially available divinylbenzene (a mixture of about 55% by weight of divinylbenzene and about 45% by weight of ethylvinylbenzene). Dissolved in part. Add 0.1 part by weight of "Parchable IB" (t-butylperoxyisobutyrate, manufactured by NOF CORPORATION) as a polymerization initiator, and then mold the mold with the opposite edges of glass plates sealed with adhesive tape at 3 mm intervals. Filled. Room temperature to 60
Cast polymerization was carried out under conditions of 1 hour to 60 ° C., 8 hours at 60 ° C., 4 hours from 60 ° C. to 110 ° C., and 3 hours at 110 ° C. The molded body (3 mm-thick plate) obtained without causing liquid leakage from the sealed portion of the adhesive tape during polymerization was transparent at all sites. 546.1 nm
The refractive index (hereinafter abbreviated as ne) measured at the wavelength (e line) of 1.60 was 1.60, and the specific gravity (hereinafter abbreviated as ρ) measured at 23 ° C. was 1.06.

Comparative Example 1 0.33 parts by weight of "perbutyl IB" was added to 90 parts by weight of styrene and 10 parts by weight of commercially available divinylbenzene, and a plate having a thickness of 3 mm was cast-molded in the same manner as in Example 1.

During the molding, some liquid leaked from the sealed portion of the adhesive tape, and a streak-like moistened whitened portion was observed from the peripheral portion to the central portion of the molded body.

Example 2 30 parts by weight of the styrene-based precipitation polymer prepared in Reference Example 2 was dissolved in 35 parts by weight of styrene and 35 parts by weight of commercially available divinylbenzene. To this solution, 2-methacryloyloxyethyl isocyanate was added [OH] / [NCO] =
An amount of 1/1 (molar ratio) is added, and 0.05% of di-n-butyltin dilaurate is further used as a urethane-forming catalyst.
By weight part, urethane reaction was carried out at 50 ° C. for 4 hours.

Polymerization initiator "Patchable IB" was added to 0.15
After adding parts by weight, a transparent cast molded plate was obtained in the same manner as in Example 1. Liquid leakage during molding and whitening of the molded body were not observed. Ne = 1.60 of molded body, ρ = 1.0
It was 6.

Comparative Example 2 Instead of the styrene-based precipitation polymer of Example 2, Reference Example 3
Using a styrene-based solution polymer prepared by
A cast molded plate was obtained in the same manner as in Example 2. The molded body was colored yellow and was unsuitable as an optical material.

Comparative Example 3 Instead of the styrene-based precipitation polymer of Example 2, Reference Example 4
A cast molded plate was obtained in the same manner as in Example 2 using the styrene-based emulsion polymer prepared in. The molded plate had turbidity (haze) that is considered to be due to the emulsifier contained in the styrene-based emulsion polymer, and was unsuitable as an optical material.

Comparative Example 4 Instead of the styrene-based precipitation polymer of Example 2, Reference Example 5
A cast molded plate was obtained in the same manner as in Example 2 using the styrene-based turbid polymer prepared in. The molded plate had a haze that is considered to be caused by the dispersant contained in the styrene-type suspended polymer, and was unsuitable as an optical material.

Examples 3 to 4 and Comparative Examples 5 to 6 The same as Example 2 except that the degree of polymerization, the molar percentage of 2-hydroxyethyl methacrylate copolymerization, the amount of the precipitated polymer used and styrene, and the amount of commercially available divinylbenzene are different. A cast molded plate was obtained in the same manner. The molding results are shown in Table 1.

[0068]

[Table 1] Examples 5 to 6 The degree of polystyrene conversion measured by GPC is about 10.
A p-methylstyrene precipitation polymer obtained by copolymerizing 15 mol% of hydroxymethylstyrene, which is No. 00, was dissolved in p-methylstyrene and commercially available divinylbenzene. After sufficient dehydration with sodium sulfate, methacryloyl isocyanate was added in a dry / nitrogen gas atmosphere and a urethane reaction was carried out at room temperature for 1 hour. 0.15 parts by weight of "perbutyl IB" was added and a cast molded plate was obtained in the same manner as in Example 1. Table 2 shows the results.

[0069]

[Table 2] Example 7 The degree of polystyrene conversion measured by GPC is about 30.
40 parts by weight of a styrene-based precipitation polymer obtained by copolymerizing 20 mol% of α-methylstyrene and 5 mol% of aminoethyl methacrylate, which is 0, was dissolved in 35 parts by weight of styrene and 25 parts by weight of commercially available divinylbenzene. Add aminoethyl methacrylate and an equivalent amount of glycidyl methacrylate and add 5
The amino group and the epoxy group were reacted at 0 ° C. for 6 hours.
A cast molded plate was obtained in the same manner as in Example 1 except that 0.1 part by weight of "perbutyl IB" was added. There was no liquid leakage during molding and whitening of the cast plate. Ne = of the molded body
The values were 1.60 and ρ = 1.06.

Example 8 20 parts by weight of polymethylmethacrylate (polystyrene-equivalent number average molecular weight of 2100 by GPC) precipitated and polymerized in a methanol / water solvent was dissolved in 75 parts by weight of methyl methacrylate and 5 parts by weight of ethylene glycol dimethacrylate. Then, add 0.1 part by weight of AIBN, and then 3
The peripheral edges of glass flat plates facing each other at intervals of mm were filled in a mold sealed with an adhesive tape. 1 hour from room temperature to 50 ° C, 8 hours at 50 ° C, 4 hours from 50 ° C to 95 ° C, 9
Cast polymerization was carried out under the condition of keeping at 5 ° C. for 2 hours.

All parts of the obtained molding were transparent without causing liquid leakage from the sealed part of the adhesive tape during the polymerization.

[0072]

According to the present invention, it is possible to provide a cross-linkable optical material which is transparent, has a high refractive index and is lightweight.

Claims (5)

[Claims] 1. A crosslinkable optical material containing a polymer polymerized by a precipitation polymerization method. 2. The crosslinkable optical material according to claim 1, which is obtained by polymerizing a solution of a polymer polymerized by the precipitation polymerization method and a radical-polymerizable monomer that dissolves the polymer. . 3. The crosslinkable optical material according to claim 1, wherein the polymer polymerized by the precipitation polymerization method contains a radically polymerizable functional group in an amount of 1 mol% or more in the precipitation polymer. . 4. The crosslinkable optical material according to claim 1, wherein the polymer polymerized by the precipitation polymerization method contains a styrene-based monomer as a main component. 5. The crosslinkable optical material according to claim 2, wherein the radically polymerizable monomer capable of dissolving the polymer polymerized by the precipitation polymerization method is a styrene compound or divinylbenzene.