JP3524150B2 - Method for producing sulfur-containing polymer particles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlens for an optical connector, an optical switch, an optical fiber, an optical branch in optical circuits, a junction circuit, an optical multiplex branch circuit, a light intensity controller, The present invention relates to a method for producing high-refractive-index sulfur-containing polymer particles that can be suitably used for applications such as light-emitting diode condensing lenses, retroreflective road lane markings, and light guide plates. 2. Description of the Related Art Plastic optical materials have been rapidly spread in recent years as optical elements such as spectacle lenses and camera lenses, because they are lighter, harder to break, and have better moldability than inorganic glass. Examples of the plastic optical materials widely used at present include resins such as polymethyl methacrylate and diethylene glycol bisallyl carbonate. These have excellent properties such as light weight, excellent impact resistance, easy dyeing, and good workability such as cutting and polishing. However, the refractive index (n) of the inorganic glass is 1. For example, in order to obtain optical properties equivalent to that of a glass lens, it is necessary to increase the center thickness, edge thickness, curvature, and the like of the lens,
For this reason, there was a drawback that the entire body was inevitably thick. Further, transparent particles (beads) having a high refractive index include, for example, a light guide plate (Japanese Patent Laid-Open No. 4-29289) for improving the brightness of a liquid crystal display panel and a lane marking having a retroreflective property. Japanese Patent Publication No. 51-6693). Conventionally, as such high refractive index transparent beads, glass beads made by blending lead, titanium, barium and the like as components have been used, and the production cost is extremely high, and inexpensive high refractive index The demand for transparent beads made of an organic polymer was strong. A polymer having a high refractive index can be obtained by introducing a sulfur atom or an aromatic ring into the main chain structure of the polymer as disclosed in JP-A-63-277244 and JP-A-2-58.
001 and the like. JP-A-63-277
In JP-A-244, a divinyl compound is reacted with an aromatic dithiol compound, and in JP-A-2-58001, a dithiol compound is reacted with a polyvalent acrylic compound.
A compound having a high refractive index is obtained by reacting a compound having at least two reactive unsaturated groups per molecule. [0006] Most of the dithiol compounds used in the above-mentioned polymerization reaction, and some of the divinyl compounds are solid at room temperature. Only polymerization had taken place.
For this reason, a method of obtaining high refractive index polymer particles by reacting monomers constituting a high refractive index polymer by a suspension polymerization method or the like has not been known. In Japanese Patent Application Laid-Open No. 61-19602, a solvent which dissolves a monomer but does not dissolve a polymer is used as a polymerization solution, and the resulting polymer is precipitated in the form of fine particles. A dispersion polymerization method is disclosed. What is obtained in this system is vinyl polymer particles, and this method was not intended to obtain polymer particles having a high refractive index. [0008] In view of the above, an object of the present invention is to provide a method for producing particles comprising a sulfur-containing polymer having a high refractive index. The gist of the present invention is to provide 45 to 55 mol% of a dithiol compound represented by the following general formula (I), and at least two reactive unsaturated groups per molecule. 55 to 45 mol% of a compound having the following formula: in a solvent which dissolves itself but does not dissolve a polymer obtained by polymerizing them, is added with a polymer dispersant and reacted to produce sulfur-containing polymer particles. It exists. [0010] In the formula, R ¹ and R ² are the same or different and represent hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group having 1 to 3 carbon atoms, a phenyl group, a hydroxyl group, chlorine or bromine. n represents an integer of 1 to 3. The dithiol compound represented by the above general formula (I) is not particularly restricted but includes, for example, 1,4-benzenedithiol, 1,3-benzenedithiol, 1,2
-Benzenedithiol, 2-methyl-1,4-benzenedithiol, 2-ethyl-1,4-benzenedithiol, 2-methoxy-1,4-benzenedithiol, 2-
Chloro-1,4-benzenedithiol, dimercaptodiphenyl sulfide, bis- (4-mercapto-3-methylphenyl) sulfide, bis- (4-mercapto-
3-methoxyphenyl) sulfide, bis- (4-mercapto-3-chlorophenyl) sulfide, 3,4'-
Dimercaptodiphenyl sulfide, 1,4-bis-
(4-mercaptophenylthio) benzene and the like, and one or more of these are used. The amount of the dithiol compound is 45 to 55 mol% of the total monomers. When the amount is less than 45 mol%, a polymer having a high refractive index cannot be obtained, and when the amount exceeds 55 mol%, the degree of polymerization of the polymer does not increase and polymer particles (beads) cannot be obtained in the polymerization process. Is done. The compounds having at least two reactive unsaturated groups per molecule used in the present invention include, for example, diallyl phthalate, diallyl succinate, diallyl adipate, diglycol bisallyl carbonate, diallyl maleate, diallyl maleate Allyl group-containing compounds such as fumarate; polyethylene glycol di (meth) acrylate, bisphenol A di (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A tetrabromodi (meth) acrylate, bisphenol A polyethoxytetrabromodi (meth) ) Acrylates such as 9,9-bis (4- (meth) acryloyloxyphenyl) fluorene and 2,2-bis (4- (meth) acryloylthiophenyl) sulfide Compounds; arylidene compounds such as diarylidenepentaerythritol, diarylidenepentaerythritol, and diarylidenetetramethylolcyclohexanone; vinyl compounds such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; One or more of these are used. As the solvent used in the polymerization reaction of the present invention, a solvent which dissolves the above-mentioned monomer but does not dissolve the produced polymer is used. Examples of the solvent include alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol; ether alcohols such as ethylene glycol monomethyl ether and ethylene glycol monobutyl ether; ethers such as ethyl ether, trioxane, tetrahydrofuran and dimethoxyethane; acetic acid Organic acid esters such as methyl and ethyl acetate; acetone,
Ketones such as methyl ethyl ketone; water and the like; one or more of these are used. In the present invention, a polymer dispersant is added to the above-mentioned solvent, and then the above-mentioned monomer is added to carry out polymerization. Examples of the polymer dispersant include (meth) acrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, (meth) acrylic acid-β-hydroxyethyl, (meth) acrylic acid-β -Hydroxypropyl, (gamma) -hydroxyethyl (meth) acrylate, diethylene glycol mono (meth) acrylate,
Glycerin mono (meth) acrylate, N-methylol (meth) acrylamide, vinyl acetate, vinyl propionate, vinyl butyrate, (meth) acrylamide, vinylpyrrolidone, vinylpyridine, vinylimidazole, ethyleneimine, and other (co) polymers A hydrophilic polymer such as polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamide, celluloses, polyvinyl alcohol and the like, and these hydrophilic polymers and styrene;
Copolymers with α-methylstyrene, (meth) acrylonitrile and the like, block polymers, graft polymers and the like are mentioned. As the polymer dispersant, one having high affinity and adsorptivity to the polymer particle surface and high solubility in a solvent is selected. The molecular weight of the above-mentioned polymer dispersant is from 10,000 to 30 from the viewpoint of making the dispersing effect and the viscosity of the polymerization system appropriate.
0000 is preferred. Further, the amount of the polymer dispersant added is preferably 0.5 to 25 parts by weight, more preferably 2 to 15 parts by weight, based on 100 parts by weight of all monomers. The sulfur-containing polymer particles of the present invention are obtained by adding a dithiol compound represented by the above general formula (I) and a compound having at least two reactive unsaturated groups per molecule to a solvent containing the above polymer dispersant. And polymerized. The polymerization initiator in the above polymerization reaction is not particularly limited as long as it is soluble in the solvent used. Examples thereof include benzoyl peroxide, t-butyl peroxide, lauroyl peroxide, diisopropyl peroxycarbonate,
2,2'-azobisisobutyronitrile, azobiscyclohexanecarbonyl, t-butyl hydroperoxide and the like. The amount of the polymerization initiator to be added is preferably from 0.1 to 10 mol%, based on the amount of the compound having at least two reactive unsaturated groups per molecule.
0.5-5 mol% is more preferable. Further, instead of using the polymerization initiator, the polymerization can be started by irradiation with active energy rays such as ultraviolet rays. After the completion of the above polymerization reaction, the polymer slurry is recovered, washed, and dried by operations such as centrifugation and decantation to obtain the sulfur-containing polymer particles of the present invention. The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Example 1 Synthesis of Sulfur-Containing Polymer Particles A 500 ml eggplant flask was charged with 180 ml of tetrahydrofuran and 120 ml of methanol as a solvent, and further charged with 6 g of polyvinylpyrrolidone (weight average molecular weight of 40,000) as a polymer dispersant. Then, 19.5 g (0.15 mol) of p-divinylbenzene purified by distillation under reduced pressure and 37.5 g of dimercaptodiphenyl sulfide
(0.15 mol) and 0.45 g of 4,4'-azobisisobutyronitrile as a polymerization initiator were added to the flask. Nitrogen gas was purged while stirring, and the mixture was left for 1 hour while flowing a small amount. Thereafter, polymerization was carried out for 10 hours while stirring in a constant temperature water bath at 60 ° C. The obtained dispersion was cooled, and polymer particles were collected with a centrifuge. The particles were sufficiently washed with methanol and dried under reduced pressure. Yield 8
It was 0%. Measurement of Refractive Index The obtained sulfur-containing polymer particles were dissolved in dichloromethane and cast on a smooth film-forming plate to form a cast film, and this film was subjected to an ellipsometer (DVA, manufactured by Mizojiri Optical Co., Ltd.). -36 VW type). The average particle size of the obtained sulfur-containing polymer particles was measured with a Coulter counter (Coulter Electronics Co., Ltd., Coulter Multisize II). The results are shown in Table 1. Examples 2 to 5 Sulfur-containing polymer particles were obtained in the same manner as in Example 1 except that the monomer composition and the compounding amount were changed as shown in Table 1.
The refractive index of the obtained sulfur-containing polymer particles was measured and is shown in Table 1. Comparative Example 1 In a 500 ml eggplant flask, methanol 32 was used as a solvent.
Then, 6 g of polyvinylpyrrolidone (weight average molecular weight of 40,000) was charged as a polymer dispersant and completely dissolved. Then 32 g (0.25 mol) of styrene,
0.2 g of 4,4'-azobisisobutyronitrile was added. Nitrogen gas was purged while stirring, and the mixture was left for 1 hour while flowing a small amount. Thereafter, polymerization was carried out for 15 hours while stirring in a constant temperature water bath at 60 ° C. The obtained dispersion was cooled, and polymer particles were collected with a centrifuge. The polymer particles were sufficiently washed with methanol and dried under reduced pressure. The yield was 95%. The refractive index of the polymer particles was measured in the same manner as in Example 1, and is shown in Table 1. Comparative Example 2 In place of styrene, 45 g of methyl methacrylate (0.
Polymerization was carried out in the same manner as in Comparative Example 1 except that 25 mol) was used, and the refractive index of the obtained polymer was measured. The results are shown in Table 1. Comparative Example 3 A reaction was carried out in the same manner as in Example 1 except that the monomers were charged with the monomer compositions shown in Table 1. The recovered polymer was a low molecular weight substance, did not grow particles, and could not be formed into a film by casting. [Table 1] The constitution of the present invention is as described above, and it is possible to provide high-refractive-index sulfur-containing polymer particles which can be suitably used for a road marking having a retroreflective property. it can.

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Claims (1)

(57) Claims 1. 45 to 55 mol% of a dithiol compound represented by the following general formula (I), and a compound 55 having at least two reactive unsaturated groups per molecule. A method for producing sulfur-containing polymer particles, characterized in that a polymer dispersant is added and reacted in a solvent which dissolves in itself but does not dissolve a polymer obtained by polymerizing them in an amount of up to 45 mol%. . Embedded image In the formula, R ¹ and R ² are the same or different and represent hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group having 1 to 3 carbon atoms, a phenyl group, a hydroxyl group, chlorine or bromine. n is 1
Represents an integer of 1 to 3.