JPH09258485A - Production of polymer particles for electrophotographic development having narrow particle size distribution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce polymer particles used for an electrophotographic developer and having narrow particle size distribution. SOLUTION: A polymer dispersant soluble in a hydrophilic org. liq. is added to the hydrophilic org. liq. by 0.1-5wt.% and a mixture of two or more kinds of vinyl monomers including a styrene monomer and (meth)acrylic ester is further added by an amt. <=20 times the amt. of the dispersant. The monomers are soluble in the org. liq. and a produced polymer is swellable in the org. liq. but slightly soluble in the org. liq. The monomers are then polymerized under stirring to obtain the objective polymer particles having 1-100μm average particle diameter. Particles each having a particle diameter in the range of (the average particle diameter) ±25% account for >=95wt.% of all the particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polymer particles having a narrow particle size distribution used in a developer for electrophotography.

[0002]

2. Description of the Related Art Heretofore, various studies have been made and a number of patents have been applied for a method for producing polymer particles for an electrophotographic developer having a narrow particle distribution.

One is a so-called suspension polymerization method, in which droplets of vinyl monomer are formed in water with a suitable dispersion stabilizer, and a polymer is prepared by using a suitable oil-soluble polymerization initiator. This is a method of synthesizing particles. However, when the polymerization is carried out under normal stirring conditions, the polymer adheres to the reaction vessel wall, stirring blades, etc., and even if polymer particles are produced, it has a large diameter of several hundred μm to several mm.
As for the particle size distribution, most of the particle size distribution was very broad, because the stochastic factors of droplet breakup and coalescence during polymerization were mostly controlled. As a countermeasure for this, polymerization conditions such as bulk polymerization or a method in which a part of the polymer is dissolved in a monomer to give a certain degree of viscosity and then suspension polymerization is performed or various surface active suspensions are performed. A method was proposed in which turbidity stabilizers and poorly water-soluble inorganic fine powders were used or used in combination, but in all cases, the particles produced were large in diameter and the distribution was only slightly improved. Is.

Further, as a method for obtaining a fine polymer, there is one called a fine suspension polymerization method. This method takes advantage of the fact that polymerizable monomer droplets are stabilized under a fairly high concentration of suspension stabilizer, and thus polymerization is carried out under conditions free of fragmentation and coalescence. It is the one to try. Therefore, in order to obtain polymer particles having a narrow particle size distribution, a problem is how to disperse the polymerizable monomer in the aqueous medium before the initiation of polymerization.

Therefore, a homomixer, a homogenizer, an atomizer, a one-liquid fluid nozzle, a gas-liquid fluid nozzle,
It was devised to suspend and disperse in water by mechanical and physical means such as electroemulsification, but it is possible to disperse it as fine droplets, but the conditions for adjusting the particle size distribution are delicate, It is almost impossible to narrow the distribution,
In particular, in this case, the dispersion stabilizer having a relatively high concentration caused the polymerization to occur concurrently in the aqueous phase, and the generation of ultrafine particles having a diameter of 0.1 to 1 μm was a problem.

On the other hand, according to the emulsion polymerization method, since the polymerization proceeds through the micelles generated by the surfactant, each particle grows uniformly, and the particle size distribution is very well adjusted by setting suitable polymerization conditions. A dispersion is obtained. However, the polymer particle size is very small, 0.1 to 1 μm, and in order to obtain particles with a diameter of several μm, in a system in which generation of new particles is suppressed, the above-mentioned fine particles are used as nuclei. It is necessary to use a so-called seed emulsion polymerization method in which a polymerizable monomer is post-added to grow particles. However, the growth rate of the particles is low, and it is necessary to carry out several steps continuously in order to obtain large-sized particles, and the polymerization process is long and there are many disadvantages in terms of cost.

Japanese Patent Publication No. 57-24369 describes a method for improving the absorption efficiency of monomers by improving the seed emulsion polymerization method so that the seed particles are swelled in two stages.
According to this, although it is possible to obtain a polymer having a well-defined particle size distribution and a large diameter, this polymerization method is not only complicated in operation but also requires a large swelling time in addition to the polymerization time. However, it also has a drawback that the polymerization conditions are very delicate.

The third method is called dispersion polymerization in an organic liquid. This is one in which the polymerizable monomer dissolves, but the resulting polymer becomes insoluble and attempts to carry out polymerization in a system in which it precipitates. However, when the polymerization is simply carried out in such a system, the polymer forms a sticky substance, a glassy substance, a lump or the like during or at the end of the polymerization to obtain a stable polymer dispersion liquid. However, it cannot be recovered as polymer particles. However, a block copolymer or graft copolymer in which one component is dissolved in the organic liquid and the other component is compatible with the polymer in an organic liquid in which the polymer is not dissolved is used as a dispersion stabilizer. By using it, a stable polymer dispersion is formed, so that the polymer can be recovered as particles. The organic liquid that does not dissolve the polymer varies depending on the type of the polymer, but generally includes nonpolar solvents such as aliphatic hydrocarbons, and polar solvents such as alcohols having a small number of carbons. Particularly, the invention relating to a method for producing a stable dispersion in which a polymer is dispersed in an organic liquid mainly containing an aliphatic hydrocarbon is described in JP-B-46-16887, JP-A-46-38246, and JP-A-
No. 6-40685, No. 47-296 and the like, and inventions relating to a method for producing a dispersion in a polar solvent include Japanese Patent Publication Nos. 54-2238 and 57-46445.
However, all of them relate to a method for producing a stable polymer dispersion in an organic liquid, and the target particle size is 1
It was not more than μm, and it was not particularly necessary to control the particle size distribution.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain polymer particles for an electrophotographic developer, which have industrially simple reaction steps and have quality reproducibility and which have a narrow particle size distribution.

[0010]

The present invention provides a hydrophilic organic liquid containing a polymer dispersant which dissolves in the hydrophilic organic liquid.
In the range of 1 to 5% by weight, in addition to this, a styrene-based monomer which dissolves in the hydrophilic organic liquid or the polymer produced is swollen by the hydrophilic organic liquid but hardly dissolved A mixture of two or more vinyl monomers composed of acrylic acid ester or a mixture of two or more vinyl monomers composed of styrene monomer and methacrylic acid ester is used in an amount of 20 times or less with respect to the polymer dispersant. The amount is added and polymerized while stirring, the average particle diameter is 1 to 100 μm, and the average particle diameter is ± 25.
% Of particles having a particle size of less than 95% by weight is obtained, which is a method for producing polymer particles for an electrophotographic developer having a narrow particle size distribution.

As the hydrophilic organic liquid used in the present invention,
For example, methyl alcohol, ethyl alcohol, denatured ethyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, tert-amyl alcohol, 3-pentanol, octyl alcohol, benzyl alcohol, cyclohexanol. , Furfuryl alcohol, tetrahydrofurfuryl alcohol,
Alcohols such as ethylene glycol, glycerin, and diethylene glycol, methyl cellosolve, cellosolve,
Ether alcohols such as butyl cellosolve, isopropyl cellosolve, butyl cellosolve, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and the like can be mentioned.

These organic liquids may be used alone or as a mixture of two or more. In addition, alcohols,
And by combining with the above alcohols and ether alcohols in organic liquids other than ether alcohols,
It is possible to adjust the average particle size and the particle size distribution of the produced polymer particles by changing various SP values under the condition that the produced polymer particles of the organic liquid have no solubility.
These organic liquids used in combination include hydrocarbons such as hexane, octane, petroleum ether, cyclohexane, benzene, toluene, xylene, halogenated hydrocarbons such as carbon tetrachloride, trichloroethylene, and tetrabromoethane, ethyl ether, Ethers such as dimethyl glycol, trioxane, tetrahydrofuran, methylal,
Acetals such as diethyl acetal, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexane, butyl formate, butyl acetate, ethyl propionate, esters such as cellosolve acetate, acids such as formic acid, acetic acid and propionic acid, nitropropene , Nitrobenzene, dimethylamine, monoethanolamine, pyridine, dimethylsulfoxide, dimethylformamide, and other sulfur- and nitrogen-containing organic compounds, and water.

SO ₄ ² ~, NO ₂ ~, PO ₄ ³ ~, Cl ~, Na ⁺ , K ⁺ , Mg are added to the above-mentioned solvent composed mainly of hydrophilic organic liquid.
Polymerization may be carried out in the presence of ²⁺ , Ca ²⁺ and other inorganic ions.

The average particle size, particle size distribution, drying conditions, etc. of the polymer particles produced can be adjusted by changing the type and composition of the mixed solvent at the beginning of the polymerization, during the polymerization, and at the end of the polymerization.

Suitable examples of the dispersion stabilizer include, for example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-
Acids such as cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride, or acrylic monomers containing a hydroxyl group such as β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, acrylic Acid β-hydroxypropyl, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol Monoacrylic acid ester, diethylene glycol monomethacrylic acid ester, glycerin monoacrylic acid ester, glycerin monomethacrylic acid ester, N-methylol acrylamide, N-methylol methacrylamide, etc. Ethers of alcohols or vinyl alcohol such as vinyl methyl ether, esters such as vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and carboxyl groups, such as vinyl acetate, vinyl propionate,
Vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride and methacrylic acid chloride, nitrogen atoms such as vinylpyridine, vinylpyrrolidone, vinylimidazole and ethyleneimine, or a complex thereof. Homopolymers or copolymers of those having a ring, polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl Ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester, etc. Cellulose such as polyoxyethylene-based, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, those having the above-mentioned hydrophilic monomer and benzene nucleus such as styrene, α-methylstyrene, vinyltoluene, or derivatives thereof or acrylonitrile, methacrylonitrile It is also possible to use a copolymer with an acrylic acid or methacrylic acid derivative such as acrylamide, or a copolymer with a crosslinkable monomer such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, allyl methacrylate or divinylbenzene.

These polymer compound dispersants may be appropriately selected depending on the hydrophilic organic liquid used and the kind of the intended polymer particles, but especially the coalescence of the produced polymer particles is mainly sterically prevented. In terms of meaning, those having a high affinity for the surface of the polymer particles and an adsorptive property and a high affinity for the hydrophilic organic liquid and a high solubility are selected. Further, in order to increase the repulsion between the particles in a three-dimensional manner, one having a molecular chain of a certain length, preferably one having a molecular weight of 10,000 or more is selected. However, if the molecular weight is too high, the viscosity of the liquid is remarkably increased, the operability and the agitation property are deteriorated, and the precipitation probability of the produced polymer on the particle surface is varied, so that caution is required.

Further, it is also effective to stabilize the particles that the above-mentioned monomer of the polymer compound dispersant is allowed to partially coexist with the monomer constituting the intended polymer particles.

When used in combination with these polymer compound dispersants, metals such as cobalt, iron, nickel, aluminum, copper, tin, lead and magnesium or alloys thereof (especially 1 μm) are used.
The following is preferable) Iron oxide, copper oxide, nickel oxide,
Fine powder of inorganic compounds of oxides such as zinc oxide, titanium oxide and silicon oxide, carbon black, nigrosine dye, aniline blue, chrome yellow, phthalocyanine blue, rose bengal and other pigments, dyes, higher alcohol sulfate ester salt, alkylbenzene sulfone Acid salt, α-
Anionic surfactants such as olefin sulfonates and phosphates, alkyl amine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, alkyl dimethyl benzyl Quaternary ammonium salt type cationic surfactants such as ammonium salts, pyridinium salts, alkylisoquinolinium salts and benzethonium chloride, and nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives. For example, alanine type [eg, alkylaminopropionic acid], glycine type [eg, dodecyldi (aminoethyl) glycine,
The use of an amino acid type or betaine type amphoteric surfactant such as di (octylaminoethyl) glycine] can further enhance the stabilization of the produced polymer particles and the improvement of the particle size distribution.

Generally, the amount of the polymer dispersant used varies depending on the kind of the polymerizable monomer for forming the intended polymer particles, but is preferably 0.1% by weight to 5% by weight with respect to the hydrophilic organic liquid. . When the concentration of the polymer dispersion stabilizer is low, the produced polymer particles have a relatively large diameter, and when the concentration is high, small particles are obtained. There is little effect on reducing the diameter.

The polymer particles produced are stabilized in the hydrophilic organic liquid and by the polymer dispersion stabilizer distributed in equilibrium on the surface of the polymer particles, and the particle size distribution of the polymer produced is high. There is a close relationship between the molecular dispersion stabilizer and the addition amount of the monomer, and the amount of the monomer used is 20 times or less the amount of the polymer dispersion stabilizer, more preferably 10 times or less. Polymer particles having a narrow size distribution can be obtained.

In the present invention, the vinyl-based monomer mixture is one that can be dissolved in a hydrophilic organic liquid, for example, styrene, o-methylstyrene, m-methylstyrene, p.
-Methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, p Styrene-based monomers such as -n-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. , Methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic acid 2 -Chloroethyl, phenyl acrylate, α-chloroacrylate methyl Acrylic acid ester such as, or methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid A mixture with a methacrylic acid ester such as stearyl acid phenyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like, and a mutual mixture with a monomer containing 50% by weight or more of these and capable of being copolymerized therewith. means.

The polymer according to the present invention may be a crosslinked polymer obtained by polymerizing in the presence of a so-called crosslinking agent having two or more polymerizable double bonds.

As the cross-linking agent preferably used, divinylbenzene, divinylnaphthalene and aromatic divinyl compounds which are derivatives thereof, other ethylene glycol dimethacrylate, diethylene glycol methacrylate, triethylene glycol methacrylate, trimethylolpropane triacrylate, allyl methacrylate, tert-butylaminoethyl methacrylate,
Tetraethylene glycol dimethacrylate, 1,3-
Diethylenic carboxylic acid ester such as butanediol dimethacrylate, all divinyl compounds such as N, N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone and compounds having 3 or more vinyl groups are used alone or as a mixture. To be

As the polymerization initiator of the above-mentioned monomer, for example, 2,2'-azobisisobutyronitrile,
Azo-based polymerization initiators such as 2,2′-azobis (2,4-dimethylvaleronitrile), lauryl peroxide,
Peroxide-based polymerization initiators such as benzoyl peroxide and tert-butyl peroctoate, persulfide-based initiators such as potassium persulfate, and systems in which sodium thiosulfate, amine and the like are used in combination are used.

The concentration of the polymerization initiator is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the vinyl monomer.

Usually, the polymerization conditions are such that the concentration and blending ratio of the polymer dispersant and the vinyl monomer in the hydrophilic organic liquid are determined according to the target of the copolymer particles, the average particle size, and the target particle size distribution. It

To reduce the average particle size,
If it is desired to increase the concentration of the polymer dispersant and increase the average particle size, the concentration of the polymer dispersant is set low.

On the other hand, if the particle size distribution is to be made extremely sharp, the vinyl monomer concentration is set low, and if the distribution is relatively wide, the vinyl monomer concentration is set high, but in general, When the amount of the polymer dispersion stabilizer used is more than 20 times the amount used, it is difficult to obtain particles having an average particle size of ± 25% with a distribution of 95% or more by weight. .

After the polymer dispersion stabilizer is completely dissolved in the hydrophilic organic liquid, a mixture of two or more vinyl monomers consisting of a styrene monomer and an acrylic ester, or a styrene monomer is added. A mixture of two or more vinyl-based monomers composed of methacrylic acid ester, a polymerization initiator, and other inorganic fine powder, a surfactant, a dye, and a pigment, if necessary, are added, and the mixture is stirred by ordinary stirring (50 to 300 rpm). Polymerization is preferably carried out by heating in an inert gas stream.

Although a polymerization time of 5 to 40 hours is required to carry out the polymerization in the high polymerization rate region, the polymerization is stopped in the state of a desired particle size and particle size distribution, or a polymerization initiator is sequentially added. However, the polymerization rate can be increased.

The vinyl monomer may be added periodically during the polymerization or after the completion of the polymerization, to adjust the physical and chemical characteristics of the copolymer, the average particle size, and the particle size distribution, which are suitable for the purpose. Can be done.

For example, during the polymerization, vinyl monomers having different kinds and mixing ratios are periodically added to synthesize polymer particles having different physical properties from the central part of the polymer particles toward the outside. be able to. Further, if a dye, a pigment or the like is present at the interface, the polymer particles can be colored and the colorant can be fixed.

In addition, by using the polymer particles, which have been once polymerized, as a nucleus, the vinyl monomer is polymerized again under appropriate conditions, and a newly synthesized polymer is deposited on the surface of the core polymer. This allows the particles to grow. The vinyl monomer used at that time may be the same as the core particle, or when a different type of vinyl monomer is selected, the synthesis of spherical polymer particles coated with a different type of polymer compound It is possible.

After the completion of the polymerization, the polymer slurry is recovered by operations such as sedimentation, centrifugation and decantation.
By washing, filtering, spray drying and the like, polymer particles having a perfectly spherical particle size distribution can be obtained as a powder.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and the like of the present invention will be described below.

Comparative Example 1 In a 500 cc three-necked flask equipped with a stirring blade and a condenser, methanol 3 dried with a molecular sieve 5A was used.
Put 20g, polyvinylpyrrolidone (average molecular weight 4
(10,000) 6.4 g was added little by little with stirring to completely dissolve it. Further, 32 g of styrene and 0.2 g of 2,2'-azobisisobutyronitrile were added and completely dissolved to obtain a transparent solution. The inside of the flask was purged with dry argon gas while stirring, and left for 1 hour while flowing a small amount.

200 r in a constant temperature water bath of 60 ° C. ± 0.1 ° C.
Polymerization was started while stirring at a stirring speed of pm. After 15 minutes of heating, the liquid began to turn cloudy, and after 20 hours of polymerization it remained a cloudy and stable dispersion. It was confirmed by gas chromatography that the polymerization rate reached 98%.

The obtained dispersion liquid is cooled and centrifuged with a centrifuge.
Upon centrifugation at 000 rpm, the polymer particles had completely settled and the upper liquid was clear. The supernatant was removed, 200 g of methanol was newly added, and the mixture was washed with stirring for 1 hour. The procedure of centrifuging and washing with methanol was repeated, and finally, washing with water was performed, and filtration was performed using a 1 μm microfilter. It was confirmed that the filtrate was transparent and there were no particles of 1 μ or less.

The filtered product was air-dried for one day and one night and dried under reduced pressure at 50 ° C. for 24 hours to obtain polymer particles of white powder in a yield of 95%.

Observation with an optical microscope revealed that the particles had a completely spherical shape and were highly transparent.

Observation with a scanning electron microscope revealed that the average particle size was 3.2 μm, and the distribution was 98% in terms of weight (or volume) in the range of 2.4 μm to 4.0 μm.

Comparative Example 2 320 g of methanol dried with a molecular sieve 5A in a 500 cc three-necked flask equipped with a stirring blade and a cooling tube.
Was added, and 4.8 g of polyacrylic acid (molecular weight 250,000) was added little by little with stirring to completely dissolve it. Further, 1.0 g of methyltrioctyl ammonium chloride and 1.0 g of hydrophobic colloidal silica were added. Methyl methacrylate (48 g) and 2,2'-azobisisobutyronitrile (0.2 g) were added, the inside of the flask was purged with dry argon gas while stirring, and left for 1 hour while flowing a small amount.

100 r in a constant temperature water bath of 60 ± 0.1 ° C.
Polymerization was initiated with stirring at pm. Twenty minutes after heating, the inside of the flask began to become cloudy. Thereafter, 4.0 g of a tert-butanol solution in which 5% by weight of 2,2'-azobisisobutyronitrile was dissolved was added at 2 hour intervals, and after 8 hours, the polymerization was terminated and the mixture was cooled. The analysis by gas chromatography revealed a polymerization rate of 99.5%. The resulting dispersion is stable and has no deposits on flasks, stirring blades, etc.
There was no residue after passing through the 37 μm mesh.

Centrifugation and washing with methanol were repeated twice in the same manner as in Comparative Example 1, and finally washed with water and filtered with a 1 μm microfilter. The filtrate was transparent and free of fine particles of 1 μm or less. It was confirmed.

The product separated by filtration was air dried overnight, and then left for 5 hours for 5 hours.
It was dried under reduced pressure at 0 ° C. to obtain a polymer powder of polymethylmethacrylate in a yield of 97%. Observation with an optical microscope revealed that the particles had a completely spherical shape and were highly transparent.

Observation by a scanning electron microscope gave a distribution in which particles having an average particle diameter of 5.2 μm and contained in the range of 3.9 μm to 16.5 μm were contained in a volume ratio of 98%.

Comparative Example 3 A 500 cc three-necked flask equipped with a stirring blade and a cooling tube was dried with molecular sieves tert-butanol 330 g ethylene glycol 5 g polyethylene oxide (molecular weight 100,000) 10 g styrene-maleic anhydride copolymer 6.75 g phosphoric acid Tricalcium (1.5 g) was added and dissolved by stirring.

66 g of styrene and 0.8 g of lauroyl peroxide were added to this, and the mixture was stirred and homogenized. The inside of the flask was purged with dry argon gas and left for 1 hour with a small flow. Polymerization was started while stirring at 150 rpm in a constant temperature water bath of 60 ± 0.1 ° C. After 20 minutes from heating, the inside of the flask began to turn cloudy and polymerization was carried out for 15 hours.
Even after 15 hours, a cloudy dispersion was formed, and the polymerization rate reached 97%.

Centrifugation and washing with methanol were repeated twice in the same manner as in Comparative Example 1, finally washed with water and filtered with a 1 μm microfilter, and the filtrate was clear.
It was confirmed that there were no fine particles of μm or less.

The product separated by filtration was air dried overnight, and then left for 24 hours for 5 hours.
After drying under reduced pressure at 0 ° C., polystyrene beads were obtained with a yield of 96%.

According to observation with an optical microscope, all the particles were spherical and had good transparency. Moreover, according to the scanning electron microscope, the average particle diameters are 12.3 μm and 9.2 μm.
To 15.4 μm, the distribution was such that 95% of the particles were contained in terms of volume.

Comparative Example 4 A methanol dispersion of polystyrene was synthesized in the same manner as in Comparative Example 1. The obtained polystyrene particles were observed by a scanning electron microscope to have an average particle diameter of 3.5 μm, 2.6 μm
It contained 99% of 4.4 μm particles in terms of volume. 1. Generated dispersion liquid after polymerization 180 g, styrene 32 g, methanol 160 g, 2,2′-azobisisobutyronitrile 0.2 g, hydrophobic colloidal silica 2.
5 g was mixed and further polymerized for 20 hours.

The produced particles have an average particle size of 4.4 μm and a particle size of 3.3 to 5.5 μm, but the volume is 96.
%, And no generation of new fine particles was observed.

Comparative Example 5 Polymerization was carried out in the same manner as in Comparative Example 1. However, styrene is 1
60 g and 25 times the amount of polyvinylpyrrolidone used were used.

After the polymerization, polymer deposits were found on the flask wall, stirring blades, etc., and there were 75 g (46.9%) of the dry weight of particles which did not pass through the 37 μm mesh.
Also, as for the particles that have passed through the mesh, when observed with a scanning electron microscope, there are many fine particles with a diameter of 0.5 to 1 μm,
Filtration was very slow with a 1 μm microfilter and the filtrate was cloudy.

Comparative Example 6 Polymerization was carried out in the same manner as in Comparative Example 2. However, the added methyl methacrylate and 2,2′-azobisisobutyronitrile were used in an amount of 120 g and 5 g, respectively, which was 25 times the amount of polyacrylic acid as a polymer dispersant.

After heating and stirring for 30 minutes, white turbidity started, but after 1 hour, formation of aggregates was observed. After 2 hours, the lumps were completely formed and the dispersion liquid side was only slightly clouded.

Example 1 In a 500 cc three-necked flask equipped with a stirring blade and a condenser, methanol 3 dried with a molecular sieve 5A was used.
Put 20g, polyvinylpyrrolidone (average molecular weight 4
(10,000) 6.4 g was added little by little with stirring to completely dissolve it. Further, 28.8 g of styrene, 3.2 g of n-butyl methacrylate (n-BMA) and 0.2 g of 2,2′-azobisisobutyronitrile (AIBN) were added,
It was completely dissolved. The inside of the flask was purged with dry argon gas while stirring, and left for 1 hour while flowing a small amount.

200 r in a constant temperature water bath of 60 ° C. ± 0.1 ° C.
Polymerization was started while stirring at a stirring speed of pm. After 15 minutes of heating, the liquid began to turn cloudy, and after 20 hours of polymerization it remained a cloudy and stable dispersion. It was confirmed by gas chromatography that the polymerization rate reached 98% using ethylbenzene as an internal standard.

When the obtained dispersion was cooled and centrifuged at 2000 rpm with a centrifuge, the polymer particles were completely settled and the upper liquid was transparent. The supernatant was removed, 200 g of methanol was added, and the mixture was washed with stirring for 1 hour. The procedure of centrifuging and washing with methanol was repeated, and finally, washing with water was performed and filtration was performed with a 1 μm microfilter.
It was confirmed that the filtrate was transparent and there were no particles of 1 μ or less.

The filtered material was air-dried for 24 hours,
After drying under reduced pressure at 50 ° C., white powder of styrene-n-butyl methacrylate copolymer particles was obtained with a yield of 95%.

Observation with an optical microscope revealed that the particles had a completely spherical shape and had a very high degree of transparency.

Observation with a scanning electron microscope revealed that particles having an average particle size of 4.8 μm and having a particle size of 3.6 μm to 6.0 μm were 98% in terms of weight (or volume).

Examples 2 to 6 Copolymer particles were synthesized in the same manner as in Example 1. However, the solvent, dispersion stabilizer, vinyl monomer, initiator, etc. are the first
The conditions shown in the table were used.

[0065]

[Table 1]

The yield of the obtained copolymer particles and the particle occupancy within the average particle diameter ± 25% by scanning electron microscope observation are shown in Table 2.

[0067]

[Table 2]

Example 7 In a 500 cc three-necked flask equipped with a stirring blade and a condenser, 320 g of methanol dried with Molecular Sieve 5A.
Then, 4.8 g of polyacrylic acid (molecular weight 250,000) was added little by little with stirring to completely dissolve it. Furthermore, 1.0 g of methyltrioctyl ammonium chloride,
1.0 g of hydrophobic colloidal silica was added. While adding 33.6 g of styrene, 7.2 g of n-butyl methacrylate, 7.2 g of 2-ethylhexyl acrylate, and 0.2 g of 2,2′-azobisisobutyronitrile, while stirring,
The inside of the flask was purged with dry argon gas and left for 1 hour with a small flow.

100 r in a constant temperature water bath of 60 ± 0.1 ° C.
Polymerization was initiated with stirring at pm. Twenty minutes after heating, the inside of the flask began to become cloudy. Thereafter, a methanol solution containing 5% by weight of 2,2′-azobisisobutyronitrile dissolved therein was added in an amount of 4.0 g at intervals of 2 hours, and after 8 hours, the polymerization was completed and the mixture was cooled. The analysis by gas chromatography revealed a polymerization rate of 99.5%. The resulting dispersion was stable, had no deposits on flasks, stirring blades, etc., passed through a 37 μm mesh, and had no residue.

Centrifugation and washing with methanol were repeated twice in the same manner as in Example 1, and finally washed with water and filtered with a 1 μm microfilter. The filtrate was clear.
It was confirmed that there were no fine particles of μm or less.

The product separated by filtration was air dried overnight, and then 50 hours for 24 hours.
After drying under reduced pressure at ℃, styrene / n-butyl methacrylate / 2-ethylhexyl acrylate 3 with a yield of 97%
A polymer powder of the original copolymer was obtained.

Observation with an optical microscope revealed that the particles had a completely spherical shape and had extremely high transparency.

Observation with a scanning electron microscope revealed that particles having an average particle size of 8.0 μm and having a particle size of 6.0 μm to 10.0 μm were distributed in a volume ratio of 98%.

Example 8 A 500 cc three-necked flask equipped with a stirring blade and a cooling tube was charged with 345 g of methanol and 5 g of ethylene glycol dried with molecular sieve 5A, and 10 g of polyethylene oxide (molecular weight 100,000) and styrene-maleic anhydride copolymer were added with stirring. 7.5 g of the polymer was gradually added and completely dissolved.

To this, 42 g of styrene, 28 g of n-butyl methacrylate, 0.8 g of lauroyl peroxide and 1.5 g of tricalcium phosphate were added, the inside of the flask was purged with dry argon gas, and stirring was continued for 1 hour while flowing a small amount. It was

The flask was immersed in a constant temperature water bath of 65 ± 0.1 ° C., and polymerization was started while stirring at 100 rpm. After 20 minutes from heating, white turbidity in the flask proceeded, polymerization was continued for 5 hours, 0.4 g of lauroyl peroxide was added, and polymerization was further performed for 5 hours. A turbid dispersion liquid was formed even after the polymerization, and the polymerization rate reached 98%. According to observation with an optical microscope, all the particles were spherical and had good transparency. According to observation with a scanning electron microscope, the average particle diameter is 7.6 μm, 5.7 to 9.5 μm.
Particles of No. occupy 97% of the whole when converted into volume.

In a 300 cc three-necked flask equipped with a stirring blade and a condenser, the above-obtained dispersion 180 g styrene 28 g methanol 160 g 2,2'-azobisisobutyronitrile 0.2 g hydrophobic colloidal silica 2.8 g was added. Mix and mix at 60 ℃ ± 0.1 ℃, 100rpm under stirring 20
Polymerization was carried out for hours. In the resulting dispersion, particles having an average particle size of 9.5 μm and 7.1 μ to 11.9 μ occupy 96% of the whole in terms of volume, and almost no new fine particles are generated (by a Coulter counter). 5μ in analysis
54.0 g of a white powder polymer was obtained by the operations of washing, drying and filtering without changing the number content below.

(Evaluation) In order to confirm and evaluate the usefulness of the polymer particles obtained in the above Examples and Comparative Examples, toners for copying machines were manufactured as follows and evaluated.

Toner Production Example 1 Polymerization was carried out under the same conditions except that 48 g of styrene in Comparative Example 1 was used, and the average particle size was 5.8 μm and 4.4 μm.
Particles having a particle size distribution of 99% contained in the volume range of m to 7.3 μm were synthesized.

After the polymerization, 1.44 g of oil black HBB (manufactured by Orient Chemical Co., Ltd.) was added to the white particle dispersion liquid.
In addition, by irradiating ultrasonic waves, oil black HBB
Was dispersed in the particle dispersion. It heated for 2 hours, stirring in a 55 degreeC water tank, and the colored particle dispersion liquid was obtained. Black particles were obtained by washing, filtering and drying the particle dispersion in the same manner as in Example 1. When observed with an optical microscope, all the particles were uniformly colored, but transmitted light was seen and the particles were slightly colored.

The colored particles are treated with hydrophobic silica R972.
(Manufactured by Nippon Aerosil Co., Ltd.) was added to the particles in an amount of 1% by weight, mixed with a mixer, and passed through a 200-mesh sieve to produce a toner. The average particle size of the obtained toner is 6.0.
Particles contained in the particles having a size of 4.5 μm and 4.5 to 7.5 μm were 97%.

Toner Production Example 2 The polymerized particle dispersion obtained in Comparative Example 2 was subjected to the coloring treatment, powdering treatment and silica mixing treatment performed in Toner Production Example 1 to obtain an average particle diameter of 5.3 μm. The particles contained in 4.0 to 6.6 μm gave 95% of toner. According to an optical microscope, transmitted light was observed and the blackness was slightly thin.

Toner Production Example 3 Instead of using 48 g of styrene in Toner Production Example 1, a mixed monomer of 30 g of styrene and 18 g of acrylonitrile was used, and other operations were performed in the same manner to obtain polymer particles. The obtained particles have an average particle size of 6.0 μm, 4.5 to
It had a narrow distribution in which 99% was contained in 7.5 μm.
The subsequent operations were also performed in the same manner as in Toner Production Example 1 to obtain 96 particles having an average particle diameter of 6.2 μm and 4.7 to 7.8 μm.
% Toner was obtained. Observation with an optical microscope showed that all the particles were colored, but the degree of coloring was low.

Toner Production Example 4 The polymerized dispersion liquid obtained in Example 4 was treated in the same manner as in Toner Production Example 1 to obtain a toner. However, 1.20 g of oil black HBB was used. Average particle size 5.7μ
The particles contained in m, 4.3 to 7.1 μm were very black and no visible light was observed under a 98% optical microscope.

(Image Evaluation) The toner thus obtained was subjected to image evaluation with a Ricoh copying machine FT-4820.

Toner black solid ID 1) Fixability 2) Background stain 3) Production Example 1 0.79 Rank 1 0.35 〃 2 0.58 〃 2 0.30 〃 3 0.62 〃 1 0.41 〃 4 0 .39 〃 5 0.12 1) A value measured by a Macbeth densitometer for image density of a solid black portion after copying using an image evaluation chart for Ricoh.

2) The copy obtained in the same manner as 1) was evaluated with the following rank using a drawing tester.

5: Most of the drawn image portion is not peeled off.

4: The drawn image portion is peeled off like a plate.

3: The drawn image portion is peeled off like a broken line.

2: The drawn image portion was completely peeled off, and the peeling width was narrow.

1: The drawn image portion is completely peeled off, and the peeling width is wide.

3) A value obtained by measuring the non-image portion of the copy obtained in the same manner as 1) with a Macbeth densitometer. That is, it can be seen that the toner obtained by polymerizing styrene, methyl methacrylate, and styrene-acrylonitrile has a lower degree of coloring than the specific copolymers of the present invention, poor fixability, and poor performance. .

[0094]

As described above, according to the present invention, polymer particles which are extremely useful as an electrophotographic developer such as an electrophotographic toner and a spacer for a liquid developer having an average particle size of 1 to 100 μm and a narrow particle size distribution. Can be easily obtained.

Claims (1)

[Claims] 1. A polymer dispersant soluble in the hydrophilic organic liquid is added to the hydrophilic organic liquid in the range of 0.1 to 5% by weight, and the polymer dispersant is dissolved in the hydrophilic organic liquid. The resulting polymer is swollen or hardly dissolved in the hydrophilic organic liquid, and is a mixture of two or more vinyl monomers composed of a styrene monomer and an acrylate ester, or a styrene monomer and methacrylic acid. An average particle diameter of 1 to 100 is obtained by adding two or more vinyl-based monomer mixtures of acid esters to the polymer dispersant in an amount of 20 times or less and polymerizing with stirring.
Production of polymer particles for electrophotographic developer having a narrow particle size distribution, characterized in that particles having a particle size of μm and having an average particle size within ± 25% are 95% or more by weight. Law.