JP2625468B2 - Production method of toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a toner for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

(Prior art and its problems) Conventional toner is generally manufactured by melting and mixing additives such as a colorant, a charge control agent, and a release agent into a thermoplastic resin and then having a predetermined particle size by a pulverizer or a classifier. It has been.

However, the toner produced by such a production method has a problem in that the dispersion of the electric characteristics resulting from the non-uniform mixing of the colorant and the additives, the poor fluidity due to the irregular shape of the particles, and the reduction of the particle size are required. It involves various problems such as low yield.

Japanese Patent Laid-Open No. 57-53 discloses a manufacturing method for solving such a problem.
No. 756, JP-A-59-161, JP-A-59-123851, etc., have proposed a suspension polymerization method. This suspension polymerization method does not require pulverization, simplifies the production process, consumes relatively little energy, and can be said to have improved the above-mentioned disadvantages. However, there is a problem in dispersing the colorant and additives. Remains. In other words, in order for the polymer particles to exhibit the function as a toner, a colorant, a charge control agent for improving triboelectric charging, a release agent for preventing toner adhesion to the fixing roller, and the like are uniformly dispersed in the polymer particles. Must exist. These materials do not necessarily have an affinity for the monomer, and it is difficult to stably mix and disperse such materials in a low-viscosity monomer. However, the added material may not be present in the polymer particles. In particular, a coloring agent such as carbon black having a small primary particle diameter often has a rather strong secondary aggregate, which causes poor dispersion in a monomer and causes variations in the charge amount of toner particles, image density, and the like. Will be expanded.

(Means for Solving the Problems) An object of the present invention is to provide a method for producing a toner in which the above-mentioned colorant and the like are uniformly dispersed in a monomer composition to thereby suppress variations in the charge amount and image density. It is in.

That is, the present invention provides (1) 100 parts by weight of a vinyl monomer,
(2) dispersing and suspending a polymerizable composition containing 10 to 100 parts by weight of a polyolefin grafted resin having a molecular weight of 5,000 to 200,000 and (3) 2 to 30 parts by weight of a colorant in an aqueous medium, followed by polymerization. And a method for producing a toner.

Specific examples of the vinyl monomer used in the present invention include ethylene unsaturated olefins such as ethylene, propylene, butylene and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride. Vinyl esters such as vinyl acetate and vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, propyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate Α-methylene fatty acid monocarboxylic esters such as propyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate; acrylics such as acrylonitrile, methacrylonitrile, acrylamide Or methacrylic acid derivatives; and styrene, o- methyl styrene, m- methyl styrene, p- methyl styrene, p- methoxy styrene, p-
Styrene such as phenylstyrene and p-chlorostyrene and derivatives thereof, and the like.

The polyolefin grafted resin used in the present invention has a weight average molecular weight of 5,000 to 200,000, preferably 10,000 to
100,000. If the molecular weight is less than 5,000, the blocking resistance of the toner decreases, and if it exceeds 200,000, the fixability decreases. The weight average molecular weight is measured by gel permeation chromatography using a calibration curve with standard polystyrene. The grafting amount of the polyolefin is 5 to 50 parts by weight, preferably 15 to 35 parts by weight, based on 100 parts by weight of the main chain polymer. And the solubility in vinyl monomers decreases.

The polyolefin grafted resin can be obtained by various methods, but is preferably obtained by homopolymerizing or copolymerizing a polymerizable monomer forming a main chain in the presence of a polyolefin (eg, polyethylene, polypropylene, etc.). Examples of the polymerizable monomer forming the main chain include styrenes such as styrene, chlorostyrene and vinyl styrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate; methyl acrylate, ethyl acrylate and acryl Esters of α-methylene aliphatic monocarboxylic acids such as n-butyl acid, octyl acrylate, methyl methacrylate, ethyl methacrylate and n-butyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; No.

The weight average molecular weight of the polyolefin as a graft chain is 2,000 to 100,000, preferably 5,000 to 50,000. If it is less than 2,000, the blocking resistance of the toner decreases, and if it exceeds 100,000, the solubility in the vinyl monomer decreases.

The blending amount of the polyolefin grafted resin with respect to the vinyl monomer is 10 to 1 with respect to 100 parts by weight of the vinyl monomer.
00 parts by weight, preferably 30 to 80 parts by weight. Compounding amount is 10
If the amount is less than parts by weight, the dispersibility of the colorant and additives will not be improved, and the offset resistance during fixing will not be exhibited. Also,
If it exceeds 100 parts by weight, the viscosity when dissolved in the vinyl monomer increases, and the dispersion efficiency is remarkably reduced.

Examples of the coloring agent include known materials for toner, for example, carbon black, nigrosine dye, phthalocyanine blue, aniline blue, chrome yellow,
Quinoline Yellow, Dupont Oil Red, Rose Bengal and the like. If necessary, other additives such as a charge controlling agent such as a nigrosine dye, a quaternary ammonium salt, a molybdic acid chelate, a metal salt of naphthenic acid and a metal salt of a fatty acid, a low molecular weight polyolefin wax, a metal salt of a fatty acid, and a fatty acid ester A release agent such as a system wax, a higher fatty acid, and a paraffin wax can be used. The compounding amount of the colorant in the polymerizable composition is 1 to 30 parts by weight, preferably 5 to 20 parts by weight based on 100 parts by weight of the vinyl monomer.

The polymerizable composition of the present invention may contain, in addition to the vinyl monomer, the polyolefin grafted resin, and the colorant, other known resins as a resin for a toner. Examples of such a resin include styrenes such as styrene, chlorostyrene and vinyl styrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate and acrylic Esters of α-methylene aliphatic monocarboxylic acids such as octyl acrylate, methyl methacrylate, ethyl methacrylate and n-butyl methacrylate; homopolymers or copolymers of vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether Polymers.

As a method of uniformly mixing the above-mentioned materials, after previously dissolving a polyolefin-grafted resin and a resin known as the resin for the toner if necessary in a vinyl monomer,
A method of mixing and dispersing the colorant and the above-mentioned additives if necessary, or a method of mixing and dissolving the resins and the colorant, if necessary, the additives in the vinyl monomer, and then dispersing the resin. The former method is preferable for promoting the above. In dispersing the coloring agent and the like, a conventionally known dispersing machine such as a sand grind mill, a roll mill, and a ball mill is used.

An oil-soluble polymerization initiator such as a peroxide such as oxycarbonate, cumene hydroperoxide or benzoyl peroxide or an azo compound such as α, α'-azobisisobutyronitrile or azodimethylvaleronitrile is added to the obtained dispersion. Are mixed and dissolved. Then, polyvinyl alcohol, gelatin, water-soluble polymer substances such as starch, barium sulfate, calcium sulfate, calcium carbonate, poorly water-soluble salts such as calcium phosphate, talc, clay, inorganic polymer substances such as silicic acid, dodecylbenzene sulfonic acid, Granulation is performed by dispersing and suspending in an aqueous dispersion catalyst containing a surfactant such as sodium dodecyl sulfate as a suspension stabilizer. Next, the obtained suspension is polymerized in the same manner as in ordinary suspension polymerization to produce colored polymer particles.

After the completion of the polymerization reaction, the system is cooled, washed with water or treated with a diluted acid, and then washed with water. To remove the toner particles as a powder from the suspension from which the dispersant has been removed, the toner particles may be filtered and dried with a drier, but can also be powdered by spray drying with a spray drier. is there.

(Effects of the Invention) According to the present invention, the dispersibility of the pigment in the toner particles is improved, and the reduction in image quality and image density is improved. In addition, the charge amount as toner is stabilized, and it is effective as a developer for various electrostatic latent images.

(Examples) Hereinafter, the present invention will be described with reference to examples. The present invention is not limited to these examples.

Example 1 A copolymer of styrene and n-butyl acrylate (composition ratio 80:20) was used as a main chain in 100 parts by weight of a mixed monomer (A) of 80:20 of styrene and n-butyl acrylate, The copolymer 1
Weight-average molecular weight 7 grafted with polypropylene (weight-average molecular weight 8,600) at a ratio of 20 parts by weight to 00 parts by weight
A resin varnish (A) was obtained by dissolving 50 parts by weight of a 0,000 polypropylene grafted resin and 50 parts by weight of a commercially available styrene resin (Picolastic D150; manufactured by Hercules). After preliminarily mixing the coloring agent and the additives according to the following composition, the mixture was dispersed by a sand grind mill.

Resin varnish (A) 93.8 (parts by weight) Carbon black 4.4 (Monarch 880; manufactured by Cabot) Negatively chargeable charge control agent 1.8 (Bontron S-40; manufactured by Orient Chemical Co.) α, 100 parts by weight of the liquid thus obtained 1.0 part by weight of α'-azobisisobutyronitrile was mixed and dissolved to obtain a mixed solution.

Then polyvinyl alcohol (Gohsenol GH-17;
150 parts of a 5% by weight aqueous solution (produced by Nippon Synthetic Chemical Co., Ltd.) and 100 parts of the above mixed solution were charged into a mixing vessel of a universal mixing stirrer (manufactured by Sanei Seisakusho), and then stirred at a rotation speed of 150 rpm for 20 minutes to disperse the suspension. A suspension was obtained.

250 parts by weight of the dispersion suspension was charged into a polymerization reactor having a stirrer, a thermometer, a reflux condenser, a heating device and a nitrogen gas inlet tube, and 500 parts by weight of ion-exchanged water was charged while stirring, and then under a nitrogen atmosphere. The temperature was raised to 85 ° C., and the temperature was maintained for 5 hours to polymerize with the monomers in the suspended particles.

Thereafter, the colored polymer particles and the aqueous polyvinyl alcohol solution were separated by a filtration operation, and then the colored polymer particles were repeatedly washed with warm water at 35 to 40 ° C., and then dried with a reduced-pressure drier. The colored particles thus obtained are classified into a particle size range of 5 to 10 μ using an airflow classifier, and the toner (A)
I got

Example 2 A toner (B) was obtained using the same materials and equipment as in Example 1 except that the mixed monomer (A) was changed to a styrene monomer.

Example 3 A styrene polymer was used as the main chain in 100 parts by weight of the mixed monomer (A) used in Example 1, and 50 parts by weight based on 100 parts by weight of the polymer.
Parts by weight of polypropylene (weight average molecular weight 8,60
A resin varnish (C) was obtained by dissolving 40 parts by weight of a polypropylene grafted resin having a weight-average molecular weight of 90,000 grafted with 0) and 60 parts by weight of a commercially available styrene resin (picolastic D150; manufactured by Hercules).

A toner (C) was obtained in the same manner as in Example 1 except that the resin varnish (A) was changed to the resin varnish (C) in the premixing of Example 1.

Example 4 A copolymer of styrene-n-butyl acrylate (composition ratio: 80: 2) was added to 100 parts by weight of the mixed monomer (A) used in Example 1.
0) as the main chain, 10 parts by weight of a polyethylene-grafted resin having a weight average molecular weight of 140,000 and grafted with polyethylene (weight average molecular weight of 18,000) at a ratio of 5 parts by weight to 100 parts by weight of the copolymer, and commercially available styrene 90 parts by weight of a resin (picolastic D125; manufactured by Hercules) was dissolved to obtain a resin varnish (D).

A toner (D) was obtained in the same manner as in Example 1 except that the resin varnish (A) was changed to the resin varnish (D) in the premixing and blending of Example 1.

Comparative Example 1 A commercially available styrene resin (picolastic D150; manufactured by Helcules) was added to 100 parts by weight of the mixed monomer (A) used in Example 1.
The resin varnish (E) was obtained by dissolving 00 parts by weight.

A toner (E) was obtained in the same manner as in Example 1 except that the resin varnish (A) was changed to the resin varnish (E) in the premixing and blending of Example 1.

Table 1 shows the results of evaluating the image density of the five toners obtained in Examples 1 to 4 and Comparative Example 1.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-123854 (JP, A) JP-A-61-91668 (JP, A) JP-A-60-23860 (JP, A) 97154 (JP, A)

Claims (3)

(57) [Claims] 1. A polymerizable composition comprising (1) 100 parts by weight of a vinyl monomer, (2) 10 to 100 parts by weight of a polyolefin grafted resin having a molecular weight of 5,000 to 200,000, and (3) 2 to 30 parts by weight of a colorant. A method for producing a toner, comprising dispersing and suspending a substance in an aqueous medium and then performing polymerization. 2. A polyolefin grafted resin having a main chain of 100
2. The method according to claim 1, wherein the polyolefin is grafted at a ratio of 5 to 50 parts by weight with respect to parts by weight. 3. A toner obtained by the method according to claim 1.