JPH0545028B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing an electrophotographic toner using an emulsion polymerization method. (Prior art) In electrophotography, after a photoreceptor is uniformly charged, a light image based on an original image is exposed to the photoreceptor, and the charge on the light irradiated area is erased or reduced. An electrostatic latent image is formed thereon based on the original image, and is then visualized using a developer containing toner. This visualized toner image is generally transferred to a suitable transfer member and fixed thereon to form a so-called copy. The developer used in the above process basically consists of a coloring agent to visualize the electrostatic latent image and a binder to fix the developed image to the transfer material. They are broadly classified into so-called wet (liquid) developers and dry developers. Dry developers can be further divided into two-component developers and one-component developers, with the former consisting of a carrier and toner, and the latter consisting only of toner. In other words, a two-component developer is one that obtains toner of opposite polarity to the electrostatic charge image necessary to develop the electrostatic charge image on the photoconductor by frictional charging between a carrier and toner. A one-component developer is one that is charged by friction between the two components or by friction with other members in the developing device. Conventionally, toner for such a dry developer is generally prepared by melting and kneading a colorant such as carbon black and/or a magnetic powder such as magnetite into a thermoplastic resin to form a dispersion, and then processing the resulting dispersion using a suitable pulverizer. Toners have been manufactured by applying mechanical impact force to pulverize the dispersion to a desired particle size, and if necessary, further classifying it to form a toner (hereinafter, this method is referred to as the pulverization method). Furthermore, Japanese Patent Publication No. 43-10799 proposes a method for producing completely spherical toner particles by spray drying an emulsion obtained by emulsion polymerization. Furthermore, Japanese Patent Publication No. 51-14895, Japanese Unexamined Patent Publication No. 1983-14895,
No. 53756 proposes a method for producing toner using a suspension polymerization method. When using the suspension polymerization method, a perfectly spherical toner can be obtained. (Problems to be Solved by the Invention) The pulverization method not only requires a large amount of energy for melt-kneading and pulverization, but also the produced toner inevitably has many drawbacks. In particular, when a desirable resin is used in the melt-kneading process and the grinding process, for example, when a resin that easily melts is used, toner aggregation (caking) during storage and fogging due to toner filming on the photoconductor may occur. Furthermore, if a resin that is easily crushed is used, it will be crushed into fine toner particles in the developing device, resulting in image fogging and dirt inside the machine. In addition, the colorant dispersed in the resin appears on the surface of the pulverized toner, resulting in a decrease in the amount of triboelectric charge in high humidity conditions, and the dropout of the colorant in the developing machine, which causes carrier damage. This causes undesirable phenomena such as surface contamination and photoreceptor surface contamination. In order to solve these drawbacks of the pulverization method, methods of spray drying an emulsion obtained by emulsion polymerization as described above and methods of producing toner by suspension polymerization have been proposed. It has been found that toners obtained by these methods overcome some of the drawbacks of toners obtained by milling methods, but introduce new drawbacks. That is, since the obtained toner particles are perfectly spherical, the cleaning properties are poor, and since the emulsifier or suspending agent remains in the toner particles, the charging stability is poor.
Blocking property decreases. On the other hand, recently, a method of preserving paper that has been visualized and copied using toner by sandwiching it between sheets of vinyl chloride resin has been widely used, but this resin inevitably contains a plasticizer. As a result, conventionally well-known toners, such as toners whose main resin components are polystyrene, styrene-methacrylic acid ester copolymers, etc., soften, and the image fixed on the paper is transferred to the sheet. I found out that there is a problem with it. This means that the copied paper is
There are problems that can occur even if the cable is in contact with the electrical paper cord coated with vinyl chloride resin for a long time. Such a problem is hereinafter referred to as PVC contamination. The present invention solves the above problems. In other words, it solves the problems in the conventional toner manufacturing method and provides excellent image density, resolution, and gradation, and in particular, improves cleaning performance, charging safety, and
The present invention provides a method for producing an electrophotographic toner that has excellent blocking properties and is suitable for dry development, and the resulting toner has excellent vinyl chloride stain resistance. (Means for Solving the Problems) The present invention provides (A) an unsaturated monomer having a hydroxyl group 5 to 50% by weight (B) styrene or a styrene derivative 40 to 95% by weight (C) (A) and/or Alternatively, 0 to 55% by weight of an unsaturated monomer copolymerizable with component (B) is blended so that the total amount is 100% by weight, and emulsion polymerization is performed in the presence of a colorant and/or magnetic powder to form the main resin. producing a component and salting out the obtained emulsion polymerization liquid at a temperature above the glass transition point of the main resin component and below 150°C so that the particles of the emulsion polymerization liquid have a particle size suitable for the toner; and/ Alternatively, the present invention relates to a method for producing an electrophotographic toner, characterized in that particles obtained after salting out are heat-treated at a temperature above the glass transition point of the main resin component and below 150°C. The emulsion polymerization of the polymerizable monomer in the present invention is carried out by emulsifying and dispersing the polymerizable monomer in an aqueous medium containing an emulsifier and polymerizing the emulsion polymerization. During this emulsion polymerization, a colorant and/or magnetic powder and a polymerization initiator are present. others,
Offset prevention agent, charge control agent, fluidity improver,
A toner property improving agent such as a cleaning performance improving agent, a stabilizer for assisting emulsification and dispersion, and a chain transfer agent may be appropriately present. As a method for emulsifying and dispersing the polymerizable monomer in an aqueous medium, the polymerizable monomer, emulsifier, and aqueous medium may be stirred and mixed simultaneously, or the polymerizable monomer is added to the aqueous medium in which the emulsifier is dissolved. However, they may be mixed by stirring. Although the polymerization initiator may be added after the emulsification and dispersion, it is preferable to dissolve the water-soluble polymerization initiator in advance in the aqueous medium at the time of emulsion and dispersion. Moreover, as the polymerization initiator, an oil-soluble polymerization initiator can be used in combination, and it is preferable that this is dissolved in advance in the polymerizable monomer. Furthermore, in order to improve dispersion in the resin, the colorant and/or magnetic powder is preferably used after being dissolved or dispersed in the polymerizable monomer in advance, rather than being added after the emulsification and dispersion. The same applies to toner property improvers used as necessary. Additionally, stabilizers may be used as needed;
It may be added after the emulsification and dispersion, or it may be used after being dissolved in an aqueous medium in advance. Stirring and mixing in the emulsification dispersion may be carried out by stirring at a relatively high speed using an ordinary stirrer, but it is preferably carried out by stirring by high-speed shearing using a homomixer or the like. This also applies to the case where a colorant and/or magnetic powder and an optional toner property improver are dispersed in the polymerizable monomer. The emulsion polymerization is preferably carried out at a temperature of 20 to 120° C. after or while emulsifying and dispersing the emulsion.
In particular, it is preferable to conduct the reaction at a temperature of 50 to 80°C. This emulsion polymerization is preferably carried out until the polymerization rate reaches 99% by weight or more, particularly preferably 99.9% by weight or more. When the polymerization rate is low and the amount of residual monomer is large, toner properties, especially storage stability, tend to be poor. Further, the polymer obtained by emulsion polymerization preferably has a weight average molecular weight of 50,000 or more.
If the molecular weight becomes too small, cleaning properties and blocking resistance tend to deteriorate. In addition, the obtained polymer has a glass transition point of 30~
The temperature is preferably 90°C, particularly preferably 50 to 80°C. If the glass transition point is too low, the blocking resistance tends to decrease, and if it is too high, the fixing ability tends to decrease. The glass transition point can be adjusted mainly by selecting the polymerizable monomer to be used. Such emulsion polymerization yields particles of about 3 μm or less. Next, materials used for emulsion polymerization will be explained. As component (A), acrylic acid or methacrylic acid derivatives such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate can be used. The amount used is 5 to 5% of the resin component.
50 parts by weight, preferably 10 to 30 parts by weight. If it is less than 5 parts by weight, the vinyl chloride stain resistance, which is one of the objects of the present invention, will be poor, and if it exceeds 50 parts by weight, the moisture resistance of the toner will tend to decrease. From the viewpoint of moisture resistance, 2-hydroxypropyl acrylate, 2-methacrylate
Those having a secondary hydroxyl group such as hydroxypropyl are preferred. Component (B) includes styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,
p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-
Octylstyrene, p-n-nonylstyrene, p
Styrene and derivatives thereof such as -n-decylstyrene, p-n-dodecylstyrene, n-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene can be used. The amount used is 40 to 95 parts by weight in the resin component, and 40
If the amount is less than 1 part by weight, the toner will have poor fixing properties when copied onto paper using an electrophotographic copying device. If it is too large, the proportion of component (A) used will decrease, resulting in a decrease in PVC stain resistance. Component (C) includes ethylenically unsaturated monoolefins 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, vinyl propionate, vinyl benzoate, vinyl butyrate, methyl acrylate, ethyl acrylate, acrylic acid n
-butyl, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate,
Phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-methacrylate
Octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate,
Phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate,
α-methylene aliphatic monocarboxylic acid esters such as diethylaminoethyl acrylate and diethylaminoethyl methacrylate, acrylonitrile,
Methacrylonitrile, acrylamide, methacrylamide, and in some cases acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. can also be used.
Also, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropyl penyl ketone, N-vinylpyrrole, N-vinylcarbazole, and N-vinylindole. , N-vinyl compounds such as N-vinylpyrrolidone, and vinylnaphthalene salts, or a combination of two or more thereof can be used. Further, as the polymerizable monomer of the present invention, a compound having two or more polymerizable double bonds that can serve as a crosslinking agent can also be used in part. For example, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and derivatives thereof, diethylene carboxylic acid esters such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol triacrylate, trimethylolpropane triacrylate, N,
Divinyl compounds such as N-divinylaniline, divinyl ether, divinyl sulfite and 3
Compounds having two or more vinyl groups can be used alone or as a mixture. The amount of crosslinking agent used is preferably 0 to 20% by weight based on the total amount of polymerizable monomers,
Particularly preferred is 0 to 5% by weight. The aqueous medium used in emulsion polymerization is mainly water. The ratio of the polymerizable monomer to the aqueous medium is preferably 40/60 to 90/10 by weight of the former/latter. If this ratio is too small, emulsion polymerization will be difficult, and if this ratio is too large, the yield will decrease. As the emulsifier, anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants can be used. Among these, it is preferable to use an anionic surfactant when producing a negatively chargeable toner, and to use a cationic surfactant when producing a positively chargeable toner. In these cases, in order to improve dispersion stability, it is preferable to use a nonionic surfactant in combination. Examples of anionic surfactants include fatty acid salts such as sodium oleate and potassium castor oil, alkyl sulfate ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate, and alkylnaphthalene sulfonates. , dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate ester salts, and the like. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin, fatty acid ester, oxyethylene -Oxypropylene block polymers, etc. Examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride and stearyltrimethylammonium chloride. Examples of the zwitterionic surfactant include lauryltrimethylammonium chloride. The amount of emulsifier used is 0.01 per polymerizable monomer.
-10% by weight is preferred, particularly 0.5-5% by weight. If the amount of emulsifier used is too small, stable emulsion polymerization will be difficult, and if it is too large, the resulting toner will have poor moisture resistance. Stabilizers include water-soluble polymers such as polyvinyl alcohol, starch, methylcellulose, carboxymethylcellulose, and hydroxyethylcellulose, and these are preferably used in an amount of 0 to 1% by weight based on the polymerizable monomer. Examples of water-soluble polymerization initiators that can be used in the present invention include persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide, 4,4'-azobiscyanovaleric acid, 2,2'-azobis (2-amidinopropane) dihydrochloride, t-butyl hydroperoxide, cumene hydroperoxide, etc. can be used. Particularly when persulfate is used, the sulfate anion radical (SO ₄ ^- ) that serves as the initiation active site is present on the surface of the monomer, and the particles are stabilized by the hydrophilic group and charge of the SO ₄ ^- group, making them relatively uniform. It is easy to obtain an emulsion with a large particle size. The amount used is 0.01 per polymerizable monomer.
-10% by weight is preferred, particularly 0.1-5% by weight. If the amount of polymerization initiator is too small, the polymerizable monomer will not be completely polymerized and will remain in the toner, impairing the properties of the toner. As a polymerization initiator, peroxides such as benzoyl peroxide and t-butyl perbenzoate,
Oil-soluble polymerization initiators such as azo compounds such as azobisisobutyronitrile and azobisisobutylvaleronitrile can be used in combination. The oil-soluble polymerization initiator is preferably used in an amount of 100% by weight or less based on the water-soluble polymerization initiator. The above water-soluble polymerization initiator may be used in combination with a reducing agent. As the reducing agent, there are commonly known reducing agents such as sodium metabisulfite and ferrous chloride. The reducing agent does not necessarily need to be used, but when it is used, it is preferably used in an amount equal to or less than the amount of the water-soluble polymerization initiator. Chain transfer agents include alkyl mercaptans such as t-dodecyl mercaptan, lower alkyl xanthogens such as diisopropyl xanthogen, carbon tetrachloride, carbon tetrabromide, etc., and are used in an amount of 0 to 2% by weight based on the polymerizable monomer. Preferably. Colorants preferably used in the present invention include:
Mention may be made of pigments or dyes, such as various carbon blacks, nigrosine dyes (CI No.
50415), Aniline Blue (CINo. 50405), Calco Oil Blue (CI No. azoec Blue3), Chrome Yellow (CI No. 14090), Ultramarine Blue (CI No. 77103), Dupont Oil Red (CI No.
26105), Orient Oil Red #330 (CINo.
60505), Quinoline Yellow (CINo.47005), Methylene Blue Chloride (CINo.52015), Phthalocyanine Blue (CINo.74160), Malachite Green Oxalate (CINo.42000), Lampblack (CINo.77266), Rose Bengal (CINo. 45435),
Oil black, azo oil black, etc. can be used alone or in combination. These colorants can be used in any amount, but in order to obtain the required concentration and for economic reasons, about 1 to 30% by weight, preferably 5% by weight, in the toner.
It is used in proportions such that ~15% by weight. The pigment or dye may be subjected to various treatments for the purpose of increasing its dispersibility in the polymerization reaction system or in the toner of the present invention.
As the treatment, for example, nigrosine dye (CI
No. 50415) is treated with organic acids such as stearic acid and maleic acid. Among these colorants, particularly preferred for the toner of the present invention are various carbon blacks, such as furnace black, channel black, thermal black, acetylene black, lamp black, and the like. Furthermore, the carbon black may be surface-treated. As for surface treatment,
Examples include oxidation treatment using various oxidizing agents such as oxygen, ozone, and nitric acid, and surface adsorption treatment with organic acid esters such as dibutyl phthalate and dioctyl phthalate. When carbon black is used as a coloring agent, it is preferred to use grafted carbon black. What is grafted carbon black?
It is obtained by polymerizing the above-mentioned polymerizable monomers by bulk polymerization, solution polymerization, etc. in the presence of carbon black. The polymer component of the grafted carbon black is preferably 50% by weight or less, particularly 30% by weight based on the grafted carbon black.
The following are preferred. Grafted carbon black is preferable because it has excellent dispersion stability during emulsion polymerization, but if the polymer component is too large, the viscosity tends to become too high when dispersed in polymerizable monomers, reducing workability. do. The amount of grafted carbon black to be used is preferably determined by the amount of carbon black component. Magnetic powder is used when manufacturing magnetic toners, and it can also serve as a colorant. Preferred magnetic powders include oxides or compounds of iron such as magnetite or ferrite, or ferromagnetic elements such as nickel and cobalt. These magnetic powders preferably have a particle size of 0.01 to 3 μm, and the surface of the magnetic powder may be treated with a resin, a titanium coupling agent, a silane coupling agent, a higher fatty acid metal salt, or the like. These magnetic substances have a 20 to 80
% by weight, preferably 35-70% by weight. Less than this amount may be used as a coloring agent. Anti-offset agents are used as necessary. The offset inhibitor is present in the system in various forms during polymerization and can be incorporated into the toner product. Alternatively, it can be added later to the toner of the present invention in which no anti-offset agent is present. Various natural waxes such as carnauba wax, hydrogenated castor oil or low molecular weight olefin polymers can be used as the offset inhibitor in the present invention, and preferably low molecular weight olefin polymers are used. As the low molecular weight olefin polymer, a low molecular weight polymer of olefin or a copolymer of olefin and a monomer other than olefin is used. Here, olefins include ethylene, propylene, butene-1, etc., and monomers other than olefins include acrylic esters, methacrylic esters, etc.
As this low molecular weight olefin polymer, for example, the polyalkylene described in JP-A-55-153944 and the low-molecular-weight olefin copolymer described in JP-A-50-93647 can be used. . The molecular weight of the low molecular weight olefin polymer of the present invention may be within the concept of low molecular weight in ordinary polymer compounds, but generally the weight average molecular weight (Mw) is 1000 to 45000, preferably 2000. ~
6000. The low molecular weight polyolefin polymer of the present invention preferably has a softening point of 100 to 180°C, particularly 130 to 160°C. There is no particular limit to the amount of the low molecular weight olefin polymer that can be used in the present invention, but it is preferably in the range of 0 to 30% by weight, preferably 1 to 30% by weight based on the weight of the toner. If the amount of the low molecular weight olefin polymer is too small, no offset effect will be produced by adding it, and if it exceeds 30% by weight, gelation may occur during the polymerization reaction. Furthermore, a fluidity improver, a cleaning performance improver, etc. can be used as necessary. Although these can be present in the polymerization reaction system and present in the product toner, they are preferably externally added to the product toner afterwards. The content of each of these is 0% to 3% by weight based on the toner of the present invention.
is preferred. Fluidity improvers include silane, titanium, aluminum, calcium, magnesium, and magnesium oxides, or those obtained by hydrophobizing the above oxides with a titanium coupling agent or a silane coupling agent.Cleanability improvers include , metal salts of higher fatty acids such as zinc stearate, lithium stearate and magnesium laurate, or aromatic acid esters such as pentaerythritol benzoate. In the present invention, the charge amount and charge polarity of the product toner can be freely adjusted by selecting the polymerizable monomer and colorant, but in order to adjust the charge amount and charge polarity to more desired values, the present invention A charge control agent can also be used in combination with the colorant in the toner. The charge control agents preferably used in the present invention include Spiron Black TRH, Spiron Black TRH, and Spiron Black TRH.
Azo dyes such as TPH (Hodogaya Chemical), p-fluorobenzoic acid, p-nitrobenzoic acid, 2,4-di-
Examples include aromatic acid derivatives such as t-butylsalicylic acid, tin compounds such as dibutyl-tin oxide, and dioctyl-tin oxide.
These are preferably used in an amount of 0 to 5% by weight based on the polymerizable monomer. In the present invention, after producing the main resin component by emulsion polymerization, a salting-out agent is added to the obtained emulsion polymerization solution to perform salting-out. Salting out is preferably adjusted so that the particle size distribution of the aggregated particles is 1 to 100 μm, particularly preferably 3 to 70 μm, and mainly 5 to 25 μm. It is most preferable to adjust it so that it becomes a component. The average particle size is preferably adjusted to 9 to 15 μm. For the above adjustment, the amount of the salting-out agent is 0.1 to 5 times, preferably 0.3 to 3 times, the weight of the emulsifier in the emulsion polymerization solution.
It is preferable to use twice as much. If the amount of the salting-out agent used is too small, the salting-out effect will be insufficient, and if it is too large, the moisture resistance of the toner will be poor and the average particle size of the particles will become too large. In this salting-out process, the emulsion polymerization liquid and the salting-out agent are mixed by dropping the emulsion polymerization liquid little by little into the salting-out agent aqueous solution while stirring, or by mixing the salting-out agent aqueous solution and the emulsion polymerization liquid at a fixed ratio. This can be done by any method. In this salting-out step, the temperature is preferably higher than or equal to the glass transition point of the main resin component and lower than or equal to 150°C, particularly preferably from 20°C higher than the glass transition point to lower than or equal to 150°C. In addition, if salting out occurs at a temperature below the glass transition point, a step of heat treatment at a temperature above the glass transition point and below 150°C is provided. Such heat treatment increases the bulk density of the particles of the main resin component, improving moisture resistance, offset resistance, and durability. One possibility is to add a large amount of salting-out agent to the emulsion polymerization solution in the salting-out process to obtain a large coagulate, which is then pulverized to a particle size suitable for the toner. However, since the toner of the present invention takes a shape closer to that of the pulverized toner than the toner of the present invention, cleaning performance and toner fluidity are reduced. inferior to sex. On the other hand, in the present invention, the particles obtained by salting out can be made into a toner as is or only by being classified, and the shape of the toner particles is
It is different from the asymmetrical spherical shape of the pulverized toner, and is not perfectly spherical, but has an imperfect spherical shape, so it has excellent cleaning properties. Examples of salting-out agents include inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as formic acid and oxalic acid, and water-soluble metal salts of these acids and alkaline earth metals, aluminum, and the like. These salting-out agents can be used alone or in combination, but preferred salting-out agents are magnesium sulfate, aluminum sulfate, barium chloride, magnesium chloride, calcium chloride, sodium chloride, and/or a combination of these and an inorganic acid. . These salting-out agents are preferably used as a 0.1 to 1.0% by weight aqueous solution, particularly a 0.1 to 5% by weight aqueous solution. After salting out, toner particles can be obtained by centrifugal dehydration, further washing, drying and, if necessary, classification. Here, washing is preferable in order to completely remove the emulsifier adhering to the particles, and thereby, as well as the above-mentioned salting out, charging stability and blocking property can be improved. Washing is preferably carried out with warm water at a temperature of 40-60°C. Note that the above-described heat treatment after salting out may be inserted during the washing step or between two or more washing steps. The toner obtained according to the present invention can be used in various development processes, such as the cascade development method described in U.S. Pat. No. 2,618,552, the magnetic brush method described in U.S. Pat.
The powder cloud method described in No. 2221776, the touch-down development method described in U.S. Pat. The present invention can be used in the so-called microtoning method using magnetic toner, and the so-called bipolar magnetic toner method in which the necessary toner charge is obtained by frictional charging of magnetic toners. Further, the toner obtained according to the present invention can be used in various fixing methods, such as so-called oil-less and oil-coated heat roll methods, flash methods, oven methods, and pressure fixing methods. Furthermore, the toner of the present invention can be used in various cleaning methods, such as the so-called fur brush method and blade method. (Function) In the present invention, by salting out the emulsion polymerization liquid, the particles in the emulsion polymerization liquid are appropriately agglomerated, and have an average particle size larger than that of the particles in the emulsion polymerization liquid, and are incompletely spherical. It is possible to obtain resin particles suitable for toner that do not require pulverization. This salting-out process yields imperfectly spherical toner particles, so the toner has excellent cleaning properties, and since the salting-out process also removes the emulsifier, anti-blocking properties and charging stability are also improved. Ru. Furthermore, the toner obtained according to the present invention has no problem in fixing properties because its main resin component contains styrene or a styrene derivative as an essential component, and furthermore, it contains an unsaturated monomer having a hydroxyl group as an essential component. Therefore, it has excellent PVC stain resistance. (Example) Next, an example of the present invention will be shown. Hereinafter, "%" means "% by weight". Example 1 (1) Production of emulsion polymerization solution 3 Grafted carbon (grafted carbon GP-E-2 Ryoyu Kogyo Co., Ltd.
Co., Ltd.), 120 g of dihydroxyethyl methacrylate, 300 g of styrene as polymerizable monomers,
Butyl methacrylate 120 and 0.6 g of t-dodecyl mercaptan as a chain transfer agent were mixed and dispersed in a homomixer at 3000 rpm for 30 minutes. Next, add ion-exchanged water to this carbon dispersion.
1300g of sodium dodecylbenzenesulfonate 12 which is an anionic surfactant as an emulsifier.
g. Nonionic surfactant Nonipol PE
-68 (trade name, Sanyo Chemical Industries Co., Ltd., oxypropyl-oxyethylene block polymer) 3 g, Neugen EA170 (trade name, Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene glycol nonylphenyl ether) 3 g, and as a polymerization initiator. An aqueous solution in which 12 g of ammonium persulfate was dissolved was added and emulsified using a homomixer at 3000 rpm for 30 minutes to obtain a black pre-emulsion. Next, the black pre-emulsion was transferred to a 34-neck separable flask equipped with a stirrer, nitrogen inlet, thermometer, and condenser, and the flask was polymerized at 70°C for 5 hours under a nitrogen stream, and then cooled. An emulsion polymerization solution was obtained. The polymerization rate at this time was 99.6% or more. The molecular weight of the polymer was measured by gel chromatography using a standard polystyrene calibration curve, and found to be a weight average molecular weight (Mw) of 107,000 and a number average molecular weight (Mn) of 33,000. (2) Salting out step, final step The above emulsion polymerization solution 1 was heated to 90°C.
The solution was uniformly added dropwise to a 3% MgSO ₄ aqueous solution 1 over about 30 minutes while stirring thoroughly while maintaining the temperature of the aqueous solution at 90° C. for salting out. The mixture was kept at this temperature for an additional 30 minutes and cooled to room temperature. Next, this slurry was dehydrated using a centrifugal dehydrator, and then washed three times with warm water at 50°C. Then, it was dried in a dryer at 30 to 35°C to obtain a toner. The particle size of the obtained toner was measured using a Coulter counter, and the particle size was 3 to 70 μm, with an average particle size of 14 μm. Furthermore, the glass transition point (Tg) was measured using a differential scanning calorimeter.
When measured, it was 68℃. When this toner was further classified into 5 to 25 μm using a zigzag classifier (100MZR, manufactured by Alpin), the yield was 87% of that before classification. In the Examples and Comparative Examples below, the particle size and average particle size were determined using a Coulter counter, the glass transition point was determined using a differential scanning calorimeter, and the classification was performed using zigzag classification. Example 2 The emulsion polymerization solution 1 obtained in Example 1 was added dropwise uniformly to a 3% MgSO ₄ aqueous solution 1 heated to 60° C. while stirring sufficiently while maintaining the temperature of the aqueous solution over about 30 minutes to effect salting out. Transfer the resulting slurry to an autoclave,
Heat treatment was performed at 120°C for 30 minutes. Dehydration, washing, and drying were carried out in the same manner as in Example 1 to obtain a toner. The particle size of the obtained toner was 5 to 80 μm, with an average particle size of 15 μm. The yield when classified into 5-25 μm was 85%. Example 3 (1) Production of emulsion polymerization solution An emulsion polymerization solution was obtained in the same manner as in Example 1 except that 2hydroxyethyl methacrylate in Example 1 was replaced with 2hydroxypropyl methacrylate.
The polymerization rate at this time was 99.5% or more. or,
The molecular weight of the polymer determined in the same manner as in Example 1 is
It was Mw99000 and Mn32000. (2) Salting out step, final step The above emulsion polymerization solution 1 was heated to 60°C.
The solution was uniformly added dropwise to a 2% MgSO ₄ aqueous solution 1 over about 30 minutes while stirring sufficiently while maintaining the temperature of the aqueous solution at 60° C. for salting out. Transfer the resulting slurry to an autoclave,
Heat treatment was performed at 120°C for 30 minutes. Dehydration, washing, and drying were carried out in the same manner as in Example 1 to obtain a toner. The particle size of the obtained toner was 2 to 70 μm, with an average particle size of 11 μm. The yield when classified into 5 to 25 μm was 92%. Moreover, the glass transition point (Tg) was 66°C. Example 4 (1) Manufacturing method of emulsion polymerization liquid An emulsion polymerization liquid was obtained in the same manner as in Example 2 except that 12 g of the low molecular weight polypropylene (Viscol 550P, Sanyo Chemical Industries, Ltd. trade name) of Example 2 was added. Ta. The polymerization rate at this time was 99.5% or more.
Further, the molecular weight of the polymer determined in the same manner as in Example 1 was Mw 98,000 and Mn 33,000. (2) Salting out step, final step The above emulsion polymerization solution 1 was heated to 60°C.
The solution was uniformly added dropwise to a 2% MgSO ₄ aqueous solution 1 over about 30 minutes while stirring sufficiently while maintaining the temperature of the aqueous solution at 60° C. for salting out. Transfer the resulting slurry to an autoclave,
Heat treatment was performed at 120°C for 30 minutes. Dehydration, washing, and drying were carried out in the same manner as in Example 1 to obtain a toner. The particle size of the obtained toner was 5 to 70 μm, with an average particle size of 12 μm. The yield when classified into 5 to 25 μm was 90%. Further, the glass transition point (Tg) was 65°C. Comparative Example 1 (1) Manufacturing method of emulsion polymerization solution Grafted carbon 100g, styrene 350g,
Butyl methacrylate 180g, methacrylic acid 3g,
0.6 g of t-dodecyl mercaptan and 6 g of low molecular weight polypropylene (Viscol 550P, trade name of Sanyo Chemical Industries, Ltd.) were mixed in a homomixer.
Mixing and dispersion was performed at 3000 rpm for 30 minutes. Next, add 18g of sodium dodecylbenzenesulfonate and Nonipol to 1500g of ion-exchanged water.
Add an aqueous solution containing 4 g of PE-68 (trade name, manufactured by Sanyo Chemical Industries, Ltd.), 4 g of Neugen EA170 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 9 g of ammonium persulfate to a homomixer, and mix at 3000 rpm for 30 minutes at room temperature. A black pre-emulsion was obtained by emulsification. Transfer this black pre-emulsion to three four-necked separable flasks and heat at 70°C under a nitrogen stream for 50 minutes.
After polymerization for a period of time, the mixture was cooled to obtain an emulsion polymerization solution. The polymerization rate at this time was 99.5% or more, and when the molecular weight of the polymer was measured in the same manner as in Example 1, it was found to be Mw 85,000 and Mn 31,000. (2) Salting out, final step The above emulsion polymerization solution 1 was heated to 60°C.
The solution was uniformly added dropwise to a 1% MgSO ₄ aqueous solution 1 over about 30 minutes while stirring sufficiently while maintaining the temperature of the aqueous solution at 60° C. for salting out. Transfer the resulting slurry to an autoclave,
Heat treatment was performed at 120°C for 30 minutes. Dehydration, washing, and drying were carried out in the same manner as in Example 1 to obtain a toner. The particle size of the obtained toner was 1 to 50 μm, with an average particle size of 11 μm. The yield when classified into 5-25 μm was 93%. Moreover, the glass transition point (Tg) was 70°C. Comparative Example 2 (1) Manufacturing method of emulsion polymerization liquid An emulsion polymerization liquid was obtained in the same manner as in Comparative Example 1 except that styrene in Comparative Example 1 was replaced with methyl methacrylate. The polymerization rate at this time was 99.7% or more. Further, the molecular weight of the polymer determined in the same manner as in Example 1 was Mw 125,000 and Mn 56,000. (2) Salting out step, final step The above emulsion polymerization solution 1 was heated to 60°C.
The solution was uniformly added dropwise to a 1% MgSO ₄ aqueous solution 1 over about 30 minutes while stirring sufficiently while maintaining the temperature of the aqueous solution at 60° C. for salting out. Transfer the resulting slurry to an autoclave,
Heat treatment was performed at 120°C for 30 minutes. Dehydration, washing, and drying were carried out in the same manner as in Example 1 to obtain a toner. The particle size of the obtained toner was 3 to 90 μm, with an average particle size of 15 μm. The yield when classified into 5-25 μm was 75%. Moreover, the glass transition point (Tg) was 75°C. A plain paper copying machine (manufactured by Konishiroku Photo Industry Co., Ltd., U-
Bix1600) was used to test the electrophotographic toner properties. However, to each toner, hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., R-972) and zinc stearate were externally added as fluidity improvers at 0.6% and 0.1%, respectively. The test results are shown in Table 1.

[Table] Comparative Example 3 (Production of toner by suspension polymerization) 70 g of styrene, 30 g of butyl methacrylate, 15 g of grafted carbon, and 2 g of benzoyl peroxide were thoroughly kneaded in a homomixer, and 500 g of a 1% aqueous solution of tricalcium phosphate was added to homogenize. The mixture was further dispersed in a mixer at 3000 rpm for 30 minutes. This dispersion was transferred to a flask and subjected to suspension polymerization at 80°C for 7 hours. The polymerization rate was 99% or more. This polymer was dehydrated, washed with an aqueous hydrochloric acid solution having a pH of 2 or less, and then dried to obtain a toner. The Mw of the resin in this toner is
110,000, and Mn was 50,000. Comparative Example 4 (Production of toner by spray drying after emulsion polymerization) The emulsion polymerization solution obtained in Example 1 was spray dried at a temperature of 110° C. to obtain a toner. Comparative Example 5 (Crushing method) Styrene/butyl methacrylate = 70/30 (weight ratio) by solution polymerization using toluene as a solvent, molecular weight
A polymer with Mw of 70,000 and Mn of 30,000 was prepared, and toluene was removed by desolvation under reduced pressure to produce a white solid. 1000 g of this polymer, 50 g of carbon black, 10 g of copper phthalocyanine, and 20 g of low molecular weight polypropylene (Viscol 550P, trade name of Sanyo Chemical Industries, Ltd.)
The mixture was kneaded with two rolls and ground with a jet mill to obtain a toner. Particle diameter, average particle diameter, yield of particles of 5 to 25 μm, glass transition point of the main resin component, and tests similar to Examples 1 to 4 and Comparative Examples 1 and 2 of the toners obtained in Comparative Examples 3 to 5. The electrophotographic properties are shown in Table 2.

【table】

[Table] The electrophotographic properties of Examples 1 to 4, Comparative Examples 1 and 2, and Comparative Examples 3 to 5 were evaluated as follows. (a) Resolution: Copies were made on plain paper using the electrophotographic society test chart No. 1 and the respective developers. We compared and evaluated whether the captured images could be read in detail. (b) Image density: Judgment was made by measuring the density of the black part of the copied paper with a densitometer in the same manner as the resolution. Gradation: Evaluated in the same way as resolution using the 11-level gray area in the center of the test chart. (c) Cleanability: Each prepared developer was continuously copied using a copying machine at a temperature of 30° C. and a humidity of 80% RH, and evaluated by the number of copies until cleaning failure occurred. (d) Blocking property: Examples 1 to 4, Comparative Examples 1 to
The toner prepared in step 3 was stored at 50℃ and 95% humidity.
After being left for 72 hours, it was determined whether or not the toner had blocked, and was evaluated as ◎: Very good, ○: Excellent, △: Slightly poor, ×: Poor. (e) Charge stability: Stir the prepared developer in a copying machine, measure the amount of charge at regular intervals, and judge based on the change in the amount of charge. ◎: Very good ○: Excellent △: Slightly poor ×: Evaluated as poor. (f) Cut out the center of the test chart to a size of 50 x 50 mm in the same way as the resolution, and insert it into a vinyl chloride resin sheet.
50 x 50 mm (plasticizer dioctyl phthalate content approximately 35% by weight) was placed on top of the copied image and weighted.
Judgment was made based on the blurring of the image when stored at 500g at 40°C for 24 hours, and the evaluation was as follows: ◎: Very good, ○: Excellent, △: Slightly poor, ×: Poor. (Effects of the Invention) The present invention utilizes the emulsion polymerization method to achieve excellent resolution, image density, and gradation, as well as particularly excellent cleaning properties, charging stability, and blocking properties, as well as PVC stain resistance and fixing properties. It is possible to obtain an electrophotographic toner that has excellent properties and is suitable for dry development.

Claims (1)

[Claims] 1 (A) Unsaturated monomer having a hydroxyl group
5-50% by weight (B) Styrene or styrene derivative 40-95% by weight (C) Unsaturated monomer copolymerizable with component (A) and/or (B) 0-55% by weight, totaling 100% by weight %, emulsion polymerization is carried out in the presence of a colorant and/or magnetic powder to produce the main resin component, and the resulting emulsion polymerization liquid is adjusted so that the particles of the emulsion polymerization liquid have a particle size suitable for toner. Salting out at a temperature above the glass transition point of the main resin component and below 150°C, and/or the particles obtained after salting out at a temperature above the glass transition point of the main resin component and below 150°C.
A method for producing an electrophotographic toner, characterized by heat treatment at a temperature of ℃ or less.