JPS58147753A - Manufacture of toner - Google Patents

Abstract

PURPOSE:To obtain a toner free from unevenness of color, uniform in particle diameter, superior in fluidity, fixability, etc., by subjecting the surface of magnetic particles or colorant particles insoluble in a vinyl monomer to a specified treatment for giving oleophilic property, and then, and executing suspension polymn. of the vinyl monomer into which said particles are dispersed. CONSTITUTION:A colorant, such as carbon black, insoluble in a vinyl monomer to be used, or magnetic particles are immersed in an aq. soln. of a surfactant consisting mainly of an aliphatic acid salt, such as potassium stearate, while it is warmed, washed with an acidic soln. of 5-6 in pH, then, dried and dispersed into the vinyl monomer. This liquid dispersion is polymerized in suspension in an aq. phase contg. a suspension stabilizer to obtain a homogeneous and uniform-sized toner. No magnetic particles and colorant are separated and precipitated in the aq. phase after the polymerization, and a toner free from uneveneness of color and superior in fluidity is obtained and it can form a fogfree superior image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polymer particles containing magnetic particles or vinyl monomers in which colorant particles (hereinafter collectively referred to as filler particles) are uniformly dispersed. That is, it relates to an excellent toner manufacturing method.

Toner used in electrophotography is used to dry develop an electrostatic latent image based on an original image, but toner containing magnetic particles in polymer particles is called magnetic toner, and is used only for this purpose. However, toner containing only colorant particles is used in combination with a carrier.

Although the particles used as fillers are different, K in which such particles are incorporated into polymer particles can be prepared by mixing filler particles with polymers produced by conventional polymerization methods. For example, a filler is mixed into a solution of a polymer in an organic solvent, the solution is stirred well to make it homogeneous, and then the solution is spray-dried, or the polymer solution is mechanically dispersed in water containing filler particles and then the organic solvent is added. There is a method of recovery (wet method). These methods require equipment to remove and recover the solvent and a large amount of energy. There is also a method of melting the polymer, mixing it with filler particles, cooling it, and pulverizing it into fine particles, but as with the wet method described above, the filler particles are relatively hydrophilic, so they are dispersed uniformly in the polymer particles. Furthermore, since the polymer particles are once dissolved or solidified in a molten size, the morphology of the polymer particles is irregular.

In order to overcome these drawbacks, it has been proposed to mix filler particles into monomers and prepare polymer particles by suspension polymerization. However, the surface of filler particles is often relatively hydrophilic, and while filler particles are well dispersed in water-soluble monomers, they are uniformly dispersed in oil-based monomers. Moreover, filler particles migrate into the aqueous phase during the suspension polymerization process, making it impossible to obtain polymer particles containing a satisfactory filler. For this purpose, there is a method in which a high viscosity monomer solution is prepared in advance by dissolving a polymer in the monomer, filler particles are added to this monomer solution, and suspension polymerization is carried out. However, the polymer particles containing filler particles obtained by this method have poor dispersibility of the filler particles, and the distribution of the filler particles in the polymer particles is non-uniform. Furthermore, in this method, it is difficult to obtain polymer particles containing filler particles with a small particle size due to the high viscosity of the monomer solution, and the particle size of the polymer is also non-uniform.

As a result of intensive research into a method for producing polymer particles containing filler particles, the present inventors have found that the above problem can be solved by carrying out suspension polymerization using filler particles whose particle surfaces have been made lipophilic by a specific method. In addition, polymer particles containing filler particles can be obtained without causing solid-liquid separation such as precipitation or aggregation of filler particles during polymerization, and the filler particles can be formed into magnetic particles or vinyl monomers. The present invention was completed based on the discovery that an excellent toner can be obtained by using insoluble colorant particles. That is, in the present invention, filler particles whose surface has been made lipophilic are mixed with a vinyl monomer, and the mixture is suspended and polymerized in water in the presence of a polymerization initiator and a suspension protectant to form a vinyl-based material containing filler particles. In the method for producing polymer particles, magnetic particles and q or colorant particles insoluble in the above monomer are used as filler particles, and the lipophilization treatment is performed in a medium containing a surfactant containing a fatty acid as a main component. processing the particles in a
The toner manufacturing method is characterized in that the surfactant layer is formed on the surface of the particles by further washing with an acidic solution.

The present invention will be explained in detail below.

Oil-based vinyl monomers used in the present invention include aromatic vinyl compounds such as styrene, α-methylstyrene, ethylstyrene, vinyltoluene, and chlorostyrene, and α-unsaturated carbon atoms such as methyl methacrylate and methyl acrylate. Examples include acid esters, α,β-unsaturated nitrile compounds such as methacrylonitrile and acrylonitrile, and halogenated vinyl compounds such as vinyl chloride and vinyl bromide.

It is preferable to mix and copolymerize divinylbenzene, vinyl methacrylate, and a polyfunctional monomer such as acrylic polyester or methacrylic polyester of a polyol such as ethylene glycol or polyethylene glycol. When used, the preferred mixing amount is 10% by weight or less. Furthermore, water-soluble monomers such as acrylic acid, fluoric acid, methacrylic acid, itaconic acid, acrylic acid amide, and methacrylic acid amide may be mixed and copolymerized to an extent that does not inhibit suspension polymerization. Conjugated diene compounds such as rylene,
The obtained polymer particles containing filler particles may be mixed and copolymerized to the extent that they do not aggregate or stick to each other.

The filler particles used in the present invention are magnetic particles and/or colorant particles insoluble in the vinyl monomer. Examples of magnetic particles include magnetic metals such as iron, cobalt, and nickel, magnetic alloys of these metals with each other or with other metals, and particles of metal oxides such as iron oxide, cobalt oxide, and nickel oxide. . Examples of colorant particles insoluble in vinyl monomers include silicon oxide, carbon black, aluminum oxide, and zinc oxide. It is also possible to replace a portion of these vinyl monomer-insoluble colorant particles with vinyl monomer-soluble colorant particles. In this case, the soluble monochrome particles must not inhibit polymerization.

These filler particles need to be smaller than the polymer particles containing the filler particles, specifically 30λ to 50
It is desirable that it be about 00^.

In the present invention, the lipophilic treatment of the filler particles is carried out by mixing the filler particles with a surfactant mainly composed of fatty acids in water in any medium, and further adjusting the filler particles to a pH of less than 7, preferably 5 or more and less than 7. This is accomplished by washing with an acidic solution to form a surfactant layer on the particle surface. In this case, surfactants containing fatty acids as a main component include, for example, alkali metal salts of unconjugated fatty acids such as rosin acid, dodecenoic acid, tetradecenoic acid, and hexadecenoic acid, myristic acid, palmitic acid, stearic acid, and alagic acid. Examples include alkali metal salts of saturated fatty acids, alkaline earth metal salts of rosin acid, and preferred examples include alkali metal salts of rosin acid, hexadecenoic acid, and stearic acid.

In addition, diconcentrated acid solutions with a pH of less than 7 include lower alcohols such as methanol and ethanol, lower ketones such as acetone and methyl ethyl ketone, water, etc., as well as hydrochloric acid, sulfuric acid, nitric acid,
Examples include solutions whose pH is adjusted with mineral acids such as phosphoric acid.

The treatment temperature when the filler particles are treated in a medium containing a surfactant mainly composed of fatty acids is preferably 30 to 1
The temperature is 50°C, particularly preferably 70 to 110°C, and the treatment time is usually 0.5 to 2 hours, preferably 0.5 to 1 hour. The concentration of the surfactant containing fatty acids as a main component in the medium is not particularly limited, but is 0.2% by weight or more, preferably 1 to 60% by weight. The details of why this lipophilic treatment method is superior in producing toner are unknown, but by first treating the filler particles with a surfactant whose main component is a fatty acid, the particle surface has a core interface. An adsorption layer of two or more molecules of the active agent is formed, and then by washing with an acidic solution, the hydrophilic groups of the fatty acid component of the nuclear surfactant are adsorbed on the particle surface, forming a part with the lipophilic groups facing outward. It is presumed that because a monomolecular layer of surfactant is formed in this step, excellent lipophilicity is imparted to the hydrophilic filler particles.

The lipophilized filler particles thus obtained are extremely easily and stably dispersed in the oil-based vinyl monomer, and do not cause solid-liquid separation such as precipitation or aggregation due to gravity, magnetic force, centrifugal force, etc. There isn't.

The lipophilized filler particles are preferably mixed in the vinyl monomer in an amount of 1 to 60% by weight, particularly preferably 5 to 50% by weight.

The toner obtained according to the present invention, that is, filler particle-containing polymer particles, is prepared by adding a mixture of filler particles that have been subjected to lipophilic treatment and a vinyl monomer in the presence of a polymerization initiator and a suspension protectant.
is prepared by suspension polymerization in an aqueous phase, using a chain transfer agent if necessary. The polymerization initiator is selected from organic solvent-soluble polymerization initiators commonly used in radical polymerization of vinyl monomers. For example, benzoyl peroxide,
Acylyl peroxides such as lauroyl peroxide, aralkyl hydroperoxides such as cumene hydroperoxide and no ξ amenthane hydroperoxide, alkyl peracid esters such as t-butyl perbenzoate and 1-propyl no-acetate, dialkyl peroxides, etc. and azobisacylonitrile such as azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators are preferably used in an amount of 0.1 to 5 parts by weight, particularly preferably 0.5 to 3 parts by weight, per 100 parts by weight of the vinyl monomer. Examples of the chain transfer agent include linear or branched alkyl mercaptans, halogenated hydrocarbons, etc., and if necessary, vinyl monomer 100%
It is preferably added in an amount of 5 parts by weight or less based on the weight.

The suspending agent is used to maintain the suspension state of the vinyl monomer in the aqueous phase.

Examples of organic suspending protectants include hydrophilic synthetic polymer substances such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene gelicol, natural hydrophilic polymer substances such as gelatin and water-soluble starch, and hydrophilic substances such as carboxymethyl cellulose. Examples of inorganic suspension protectants include phosphates such as magnesium, barium or calcium, calcium carbonate, magnesium carbonate, zinc white, aluminum oxide,
Examples include aluminum hydroxide. Furthermore, these suspension preservatives can be used in combination with nonionic, anionic, or cationic surfactants. These suspension protectants are preferably used in an amount of 0.05 to 60 parts by weight per 100 parts by weight of the vinyl monomer, and when a surfactant is used in combination, it is preferably used in an additional amount of 0.05 to 60 parts by weight per 100 parts by weight of the vinyl monomer 2. Use 2 parts by weight or less.

The suspension polymerization method of the present invention is not particularly limited; An organic phase consisting of a continuous transport agent used according to the conditions and an aqueous phase consisting of water, a suspending agent and a surfactant used as necessary are mixed and stirred at a temperature below the polymerization initiation temperature. An example of a method is to suspend the vinyl monomer in the form of fine droplets of uniform particle size in an aqueous phase, and then raise the temperature of the suspension system while stirring to initiate polymerization of the vinyl monomer. The particle size and particle size distribution of the polymer particles containing filler particles obtained by this method depend on the stirring conditions before the start of polymerization, the type and amount of the suspension protectant and surfactant used as necessary, etc. By appropriately combining these, it is possible to obtain polymer particles containing filler particles having the desired particle size and Kyoko size distribution.

The amount of the aqueous phase to be used relative to the organic phase is not particularly limited, but is usually 100 to 2000 parts by weight, preferably 200 to 1000 parts by weight, based on 100 parts by weight of the organic phase. Stirring to suspend the organic phase as fine droplets in the aqueous phase is usually carried out at 300 to 20,000 rpm, preferably at 1,000 to 20 rpm.
000 rpm for 15-30 minutes, preferably 10-2
Stir for 5 minutes. In addition, the polymerization temperature when vinyl monomers are polymerized by raising the temperature of the suspension system can be determined as appropriate depending on the vinyl monomers to be polymerized, the type and amount of polymerization initiator used, etc. ~+50'C1 preferably 60
~to.

It is ℃. Since the filler particles produced by the lipophilization treatment method of the present invention are not separated from the vinyl monomer during polymerization, polymer particles uniformly containing filler particles are produced.

The polymer particles containing filler particles after polymerization route r can be separated by an operation such as centrifugation, and the separated polymer particles can be treated with water, methanol, ethanol,
Cleaned with acetone etc.

According to the production method of the present invention, the average particle diameter can be easily reduced from 0.1 to
Polymer particles containing filler particles with a very narrow particle size distribution of 50 μm can be obtained. Note that the preferred particle size for the toner is 0.1 to 30 μm.

The toner obtained by the method of the present invention has no uneven color because the filler particles are uniformly dispersed in the polymer particles, and the development finish in electrophotography is beautiful and clear. In addition, due to its spherical shape, it has excellent fluidity, and electrostatic transfer and adsorption are uniform, allowing for an even development finish.35 Other benefits include improved image efficiency, less edge effect, and fog-free images. is extremely old.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Fs30 with an average particle size of 100^ prepared by a wet method
To 1 ton of water containing 100 V of 4 particles is added 400 kg of a 20% by weight aqueous solution of potassium stearate, and the mixture is stirred at 90°C for 30 minutes. After cooling, the mixture is adjusted to pH 6 using dilute hydrochloric acid. Since the F8304 particles aggregate, they are filtered, washed twice with 300 °C of water at 80°C and twice with 300 °C of ethanol, and dried under reduced pressure.

In a 1 ton four-day flask equipped with a stirrer, flow condenser, addition funnel, and thermometer, 400 g of a 6 weight aqueous solution of hepholyvinyl malcol is added. Separately, styrene + 5Of, pendiylamide oxide 3g, t-dodecyl mercaptan 05
? and Fθ30 treated with the above sodium stearate
15 f of 4-day particles were stirred in advance at 3000 rpm under ice-cooling, and a mixed solution was added dropwise into the 4-day flask from the dropping funnel while pushing the polyvinyl alcohol aqueous solution inside the 4-day flask. After the dropwise addition was completed, stirring was continued for 60 minutes, and when the particle size of the organic phase reached a uniform particle size of 25 μm, the temperature was raised to 75° C. for polymerization.

After 5 hours of polymerization, unreacted monomers were collected under reduced pressure, and polymer particles containing F+E+504 were separated by centrifugation.
Polymer particles of No. 1402 were obtained by washing three times with warm water of No. 00-. Note that Fe4O4 particles that had undergone solid-liquid separation such as precipitation or aggregation after the completion of polymerization were not observed.

As a result of determining the particle size of the polymer particles using an electron microscope, the particle size was 25±3 μm, which was found to be excellent as a toner.

Example 2 Fe506 particles were treated in the same manner as in Example 1, except that a 10% aqueous solution of sodium hexadecenate was used instead of the 20% aqueous solution of potassium stearate in Example 1, and then polymerized to contain Fe30a. Polymer particles 1
I got 43v. Incidentally, Fe3O4 particles that had undergone solid-liquid separation such as precipitation or aggregation after the completion of polymerization were not observed. As a result of determining the particle size of the polymer particles using an electron microscope, the particle size was 20±5 μm, which was excellent as a toner.

Patent applicant: Japan Synthetic Rubber Co., Ltd. Representative Patent Attorney Akira Ito

Claims (1)

[Claims] In a method of manufacturing toner by mixing filler particles whose surface has been made lipophilic with a vinyl monomer and subjecting the mixture to suspension polymerization in an aqueous phase in the presence of a polymerization initiator and a suspension protectant, the filler particles The lipophilization treatment involves treating the electrons in a medium containing a surfactant containing a fatty acid as a main component, and further treating the electrons with an acidic solution. A method for producing a toner, characterized in that the surfactant layer is formed on the surface of the particles by washing.