JP3334207B2 - Method for producing spherical polymer particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing spherical polymer particles. More specifically, the present invention relates to a method for producing spherical polymer particles used for a coating material, a paper coating material, a toner, a liquid crystal spacer, a cosmetic material, a diagnostic reagent carrier, a chromatography filler, and the like.

[0002]

2. Description of the Related Art Conventional methods for producing spherical polymer particles include a suspension polymerization method, an emulsion polymerization method and a dispersion polymerization method.
The suspension polymerization method is a method in which dispersed oil droplets of a polymerizable vinyl monomer are formed by mechanical stirring in water containing a dispersant, and polymerization is performed using an oil-soluble polymerization initiator.

[0003] The emulsion polymerization method is a method in which a polymerizable vinyl monomer is polymerized in a surfactant micelle using a water-soluble polymerization initiator. The dispersion polymerization method is a method in which a polymerizable vinyl monomer is dissolved in a medium in which a produced polymer is not dissolved, using a polymerization initiator which is soluble in the medium, to polymerize the monomer.
When producing spherical polymer particles having an average particle diameter of 1 to 10 μm and a narrow particle diameter distribution, the spherical polymer particles produced by the suspension polymerization method are preferably manufactured to have an average particle diameter of 10 μm or less. However, it is difficult to obtain only those having a wide particle size distribution.

Although spherical polymer particles produced by the emulsion polymerization method have a narrow particle size distribution, it is difficult to make the average particle size 1 μm or more due to the mechanism of polymerization. on the other hand,
The average particle diameter is 1 to 10 μ by using the dispersion polymerization method.
m, and it is possible to produce spherical polymer particles with a narrow particle size distribution, but the deformation of the particle shape due to the limitation of the mechanism that the particles are formed by the precipitation of the polymer generated as the polymerization proceeds. The range of the polymerization system which does not cause the fluctuation of the average particle diameter and the widening of the particle diameter distribution is limited, and it is difficult to change the molecular weight of the spherical polymer particles produced in such a system over a wide range.

In the case of producing spherical polymer particles having a particularly low molecular weight, a technique using a mercaptan-based chain transfer agent as disclosed in, for example, JP-A-64-1,702 is known. In addition, when added to a polymerizable vinyl monomer in a high amount, and particularly when applied to a (meth) acrylic polymerizable vinyl monomer, there arises a problem that the particle size distribution is widened. In addition, there is a technique using an azo-based hydrochloride as a polymerization initiator as disclosed in JP-A-3-190,905, but the molecular weight distribution of the spherical polymer particles obtained is extremely wide.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing spherical polymer particles having a narrow particle diameter and a narrow molecular weight distribution and a small molecular weight. More specifically, the present invention relates to a method for producing spherical polymer particles having an average particle size of 1 to 10 μm, a narrow particle size distribution, a small molecular weight, and a narrow molecular weight distribution.

[0007]

That is, the present invention provides a method for dissolving a polymerizable vinyl monomer in a medium which does not dissolve a polymer formed therein, the radical polymerization of the polymerizable vinyl monomer ,
Monosulfide , alkyl disulfide, bis (dia
Alkylthiocarbamoyl) disulfides and aromatic di
A method for producing spherical polymer particles, characterized in that a chain transfer agent selected from the group consisting of sulfides is present.

Hereinafter, the present invention will be described in detail. Examples of the polymerizable vinyl monomer in the present invention include unsaturated aliphatic carboxylic acids such as (meth) acrylic acid; alkyl (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate; Hydroxy lower alkyl (meth) acrylate such as hydroxyethyl (meth) acrylate, alkoxyalkyl (meth) acrylate such as 2-ethoxyethyl (meth) acrylate, glycidyl (meth) acrylate, dimethylamino (meth) acrylate (Meth) acrylates such as dialkylaminoalkyl (meth) acrylate such as ethyl; (meth) acrylamide derivatives such as (meth) acrylamide; styrene, t
Styrene such as -butylstyrene and its alkyl-substituted product; vinyl esters of fatty acids such as vinyl acetate; (meth) acrylonitrile, vinylpyrrolidone, etc .; In the range of 50% by weight or less of the monomer, one or more kinds of other polymerizable vinyl monomers including the above-mentioned polymerizable vinyl monomer can be used as a copolymer component.

Examples of other polymerizable vinyl monomers other than those described above are not particularly limited as long as they are copolymerized with the above-mentioned vinyl monomers, but specific examples thereof include phenyl ester of (meth) acrylic acid. , Tetrahydrofurfuryl ester, 3-chloro-2-hydroxypropyl ester, 2
Halogen-containing esters such as chloroethyl and chloromethylstyrene; and derivatives thereof; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; allyl alcohol and its esters or ethers; vinyl sulfonic acid;
And unsaturated sulfonic acids such as styrenesulfonic acid.

The medium used in the present invention is a medium that dissolves the polymerizable vinyl monomer but does not dissolve the (co) polymer produced, and has an average particle diameter of spherical polymer particles produced. It is appropriately selected according to the monomer used in order to obtain a desired particle size distribution (for example, YA).
lmog, et. al. , British Polym
er Journal '82, pages 131-136). Specifically, alcohols such as methanol, ethanol, propanol, (di) ethylene glycol, propylene glycol, and glycerin; esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, and (di) ethylene glycol monoacetate; Ethers and ether alcohols such as diethyl ether, dioxane, tetrahydrofuran, (di) ethylene glycol monomethyl ether and (di) ethylene glycol monoethyl ether; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; hexane, cyclohexane, octane, Hydrocarbons such as benzene, toluene and xylene; halogenated carbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, chlorotoluene Motorui; acetonitrile, dimethylamine, monoethanolamine, dimethylformamide, pyridine, nitrogen-containing compounds such as nitrobenzene;
Sulfur-containing compounds such as carbon disulfide and dimethyl sulfoxide;
And water, and these can be used alone or in a mixture of two or more.

As these media, alcohols such as aliphatic lower alcohols and ethers are preferably used. In order to form spherical particles without agglomeration, deformation or fusion of the polymer produced in the present invention, it is preferable to use a dispersion stabilizer soluble in the above medium.

Examples of the dispersion stabilizer include homopolymers such as polyvinylpyrrolidone, polyacrylic acid, polyvinyl alcohol, polymethylvinyl ether, polyacrylamide, polyethyleneimine, poly (2-ethyl-2-oxazoline), various random copolymers, and graft copolymers. And synthetic polymers such as block copolymers; natural polymer derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose and hydroxypropylcellulose; and, if desired, an auxiliary stabilizer can be used in addition to the above-mentioned dispersion stabilizer. . Examples of such co-stabilizers include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and long-chain alcohols.

The polymerization initiators usable in the present invention include 2,2'-azobisisobutyronitrile,
Azo-based polymerization initiators such as 2,2'-azobis (2,4-dimethylvaleronitrile) and 4,4-azobis (4-cyanopentanoic acid); t-butyl hydroperoxide, di-t-butyl peroxide, benzoyl Peroxide,
Di-isopropyl peroxydicarbonate, t-butyl peroxyisobutyrate and a peroxide-based polymerization initiator such as hydrogen peroxide, potassium persulfate, ammonium persulfate or a system obtained by adding a reducing agent such as an amine or sodium bisulfite to these. And the like. The polymerization initiator is used in an amount of usually 0.05 to 10% by weight, preferably 0.1 to 5% by weight, based on the monomer. If the used amount of the polymerization initiator is small, the molecular weight of the produced polymer becomes high, and if the used amount is large, the reaction system becomes unstable.

The monosulfide and disulfide chain transfer agents for reducing the molecular weight of the spherical polymer particles produced in the present invention include ethyl (di) sulfide,
Alkyl (di) sulfides such as butyl (di) sulfide, bis (dimethylthiocarbamoyl) sulfide, bis (dimethylthiocarbamoyl) disulfide, bis (diethylthiocarbamoyl) sulfide, and bis (di) thiol such as bis (diethylthiocarbamoyl) disulfide Alkylthiocarbamoyl) sulfides and bis (dialkylthiocarbamoyl) disulfides, phenyl (di) sulfide, aromatic (di) sulfides such as benzyl (di) sulfide and the like, preferably bis (dimethylthiocarbamoyl) sulfide; Bis (dialkylthiocarbamoyl) disulfides, such as bis (diethylthiocarbamoyl) sulfide, bis (diethylthiocarbamoyl) disulfide, and other bis (dialkylthiocarbamoyl) sulfides Bis (dialkyl thiocarbamoyl) disulfide and the like.

The monosulfide and disulfide chain transfer agent is added in an amount of 0.01 to 15% by weight, preferably 0.05 to 10% by weight, more preferably 0.1 to 10% by weight, based on the polymerizable vinyl monomer. -5% by weight. If the addition ratio is less than 0.01% by weight, the effect of lowering the molecular weight will be insufficient, and if it exceeds 15% by weight, the shape, average particle size and particle size distribution of the spherical polymer particles produced will be adversely affected. It is also uneconomical.

The production of the spherical polymer particles in the present invention is usually carried out in a reactor equipped with a stirrer, a condenser, a thermometer and the like. One or more polymerizable vinyl monomers, a polymerization initiator and a monosulfide and / or disulfide chain transfer agent are added to a medium in which a dispersion stabilizer and, if desired, an auxiliary stabilizer are dissolved, and the mixture is stirred. The polymerization is carried out by heating the reactor. The amount of the total polymerizable vinyl monomer used is usually 5 to 45% by weight, preferably 10 to 40% by weight.
% By weight, and the amount of the dispersion stabilizer is 0.01 to 10% by weight (all in the polymerization reaction solution), but is not particularly limited.

In this case, the polymerization initiator and the monosulfide and / or disulfide chain transfer agent can be added at any time before the start of heating, during the heating, and after the polymerization temperature is reached. Both the addition method and the continuous addition method are possible. Further, in order to improve the progress of the polymerization, it is preferable to set the inside of the reactor to an inert gas atmosphere such as nitrogen gas or argon gas.

The polymerization temperature and polymerization time are appropriately determined depending on the type and amount of the polymerizable vinyl monomer, the type and amount of the polymerization initiator, and the type and amount of the monosulfide and / or disulfide chain transfer agent. However, it is approximately 30 ° C to 9
30 minutes to 1440 minutes at 0 ° C. The average particle diameter of the spherical polymer particles obtained by the above method is 1 to 10 μm
And the coefficient of variation, which is the value obtained by dividing the standard deviation by the average particle size, is 5% or less, and the particle size distribution is narrow.

The molecular weight is in the range of 1,000 to 200,000, preferably 5,000 to 150,000, more preferably 5,000 to 150,000 in terms of polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography. Is 10,000-100,0
00 range. In the method of the present invention, a polymer having a desired molecular weight can be obtained by selecting the amounts of the polymerization initiator and the disulfide chain transfer agent to be used. The molecular weight dispersity defined by the value obtained by dividing the weight average molecular weight by the number average molecular weight is in the range of 1 to 20, preferably in the range of 1.2 to 10, and more preferably in the range of 1.5 to 4.
Range.

[0020]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Example 1 135.5 parts by weight of ethanol was placed in a reactor equipped with a stirrer, a condenser, a thermometer and a nitrogen gas inlet tube, and polyvinylpyrrolidone (average molecular weight: 40,000) 3.6.
Parts by weight were added and dissolved. 60 parts by weight of glycidyl methacrylate, 0.6 parts by weight of 2,2-azobisisobutyronitrile and 0.3 parts by weight of bis (diethylthiocarbamoyl) disulfide are added to this solution, and the mixture is heated to 70 ° C. under a nitrogen atmosphere. The polymerization was carried out by heating for 3 hours. After cooling, the spherical polymer particles isolated by washing with methanol had an average particle size of 1.85 μm and a coefficient of variation of 3.1%. The spherical polymer particles were dissolved in tetrahydrofuran, and the molecular weight in terms of polystyrene was measured by gel permeation chromatography. The weight average molecular weight was 75,300 and the molecular weight dispersity was 2.6.

Example 2 135.2 parts by weight of ethanol was placed in the same reactor as in Example 1, and polyvinylpyrrolidone (average molecular weight: 40,0
00) 3.6 parts by weight were added and dissolved. 60 parts by weight of glycidyl methacrylate, 0.6 parts by weight of 2,2-azobisisobutyronitrile and 0.6 parts by weight of bis (diethylthiocarbamoyl) disulfide are added to this solution, and the mixture is heated to 70 ° C. under a nitrogen atmosphere. The polymerization was carried out by heating for 3 hours.
After cooling, the spherical polymer particles isolated by washing with methanol had an average particle size of 1.63 μm and a coefficient of variation of 2.1%. The spherical polymer particles were dissolved in tetrahydrofuran, and the molecular weight in terms of polystyrene was measured by gel permeation chromatography. The weight average molecular weight was 49,200, and the molecular weight dispersity was 2.3.

Example 3 In a reactor similar to that in Example 1, 134.6 parts by weight of ethanol was charged, and polyvinylpyrrolidone (average molecular weight: 40,0
00) 3.6 parts by weight were added and dissolved. 60 parts by weight of glycidyl methacrylate, 1.2 parts by weight of 2,2-azobisisobutyronitrile and 0.6 parts by weight of bis (diethylthiocarbamoyl) disulfide are added to this solution, and the mixture is heated to 70 ° C. under a nitrogen atmosphere. The polymerization was carried out by heating for 3 hours.
After cooling, the spherical polymer particles isolated by washing with methanol had an average particle size of 1.43 μm and a coefficient of variation of 4.1%. The spherical polymer particles were dissolved in tetrahydrofuran, and the molecular weight in terms of polystyrene was measured by gel permeation chromatography. The weight average molecular weight was 40,400 and the molecular weight dispersity was 2.4.

Example 4 135.2 parts by weight of ethanol was placed in the same reactor as in Example 1, and polyvinylpyrrolidone (average molecular weight 40,0
00) 3.6 parts by weight were added and dissolved. To this solution were added 54 parts by weight of glycidyl methacrylate, 6 parts by weight of chloromethylstyrene, and 0.2 part of 2,2-azobisisobutyronitrile.
6 parts by weight and 0.6 parts by weight of bis (diethylthiocarbamoyl) disulfide were added, and the mixture was heated to 70 ° C. under a nitrogen atmosphere.
And polymerized for 4 hours. After cooling, the spherical polymer particles isolated by washing with methanol had an average particle size of 1.84 μm and a coefficient of variation of 3.7%. The spherical polymer particles were dissolved in tetrahydrofuran, and the molecular weight in terms of polystyrene was measured by gel permeation chromatography.
6,400, and the molecular weight dispersity was 2.6.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that bis (diethylthiocarbamoyl) disulfide was not added. The obtained spherical polymer particles were dissolved in tetrahydrofuran and converted to polystyrene by gel permeation chromatography. When the molecular weight was measured, the weight average molecular weight was 2
It was 74,200 and the molecular weight dispersity was 4.4.

Comparative Example 2 Example 2 except that 2-mercaptoethanol was used instead of bis (diethylthiocarbamoyl) disulfide.
When the same polymerization as in Example 1 was carried out, the obtained spherical polymer particles had an average particle size of 2.23 μm and a coefficient of variation of 5.7%, indicating a wide particle size distribution.

[0026]

The spherical polymer particles obtained by the present invention have an average particle size of 1 to 10 μm, a narrow particle size distribution, a low molecular weight and a narrow molecular weight distribution. When such spherical polymer particles are used, for example, as a raw material for an emulsion coating, storage properties and fluidity can be improved by improving the particle size distribution characteristics, and further, it is effective for modifying a coating film by a molecular weight effect. Further, it can be suitably used as a toner raw material.

Claims (3)

(57) [Claims] In a medium in which a polymerizable vinyl monomer is dissolved but a produced polymer is not dissolved, the monomer is radically polymerized to produce spherical polymer particles. Bis (diethylthiocarbamoyl) di as transfer agent
A method for producing spherical polymer particles, wherein a sulfide is present. 2. In a medium in which a polymerizable vinyl monomer is dissolved but a produced polymer is not dissolved, the monomer is subjected to radical polymerization to produce spherical polymer particles. A method for producing spherical polymer particles, wherein a chain transfer agent selected from the group consisting of sulfides, alkyl disulfides, bis (dialkylthiocarbamoyl) disulfides, and aromatic disulfides is present. 3. In a medium in which a polymerizable vinyl monomer is dissolved but a produced polymer is not dissolved, the monomer is radically polymerized in a medium to produce spherical polymer particles. Sulfide, ethyl disulfide, butyl sulfide, butyl disulfide, bis (dimethylthiocarbamoyl) sulfide, bis (dimethylthiocarbamoyl) disulfide, bis (diethylthiocarbamoyl)
Sulfide, bis (diethylthiocarbamoyl) disulfide, phenyl sulfide, phenyl disulfide,
A method for producing spherical polymer particles, wherein a chain transfer agent selected from the group consisting of benzyl sulfide and benzyl disulfide is present.