JPH0545029B2 - - 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 uniformly charging a photoreceptor, the photoreceptor is exposed to a light image based on an original image to eliminate or reduce the charge on the light-irradiated area.
An electrostatic latent image is formed on the photoreceptor based on the original image,
Thereafter, the toner image is visualized using a developer containing toner. This visualized toner image is
Generally, the image is transferred to a suitable transfer member and fixed 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 coloring agent such as carbon black and/or magnetic powder such as magnetite in a thermoplastic resin to form a dispersion, and then processing the dispersion using a suitable pulverizer. The toner has been manufactured by applying mechanical impact force to crush 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 crushing method). . Such methods not only require a large amount of energy for melt-kneading and grinding, but also
The manufactured toners inevitably have 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 crushed toner, resulting in a decrease in the amount of triboelectric charge in high humidity conditions and the colorant falling off in the developing machine. This causes undesirable development such as contamination and contamination of the surface of the photoreceptor. In order to solve these drawbacks of the pulverization method, the
Japanese Patent No. 43-10799 proposes a method for producing completely spherical toner particles by spray drying an emulsion obtained by emulsion polymerization. In addition, in order to solve the drawbacks of the pulverization method, a method for manufacturing toner using the polymerization method was introduced.
14895, Japanese Patent Laid-Open No. 57-53756, etc., methods for producing toner using a suspension polymerization method have been proposed. When using the suspension polymerization method, a perfectly spherical toner can be obtained. Although toners obtained using such polymerization methods have heretofore overcome some of the drawbacks of toners obtained by pulverization methods, it has been found that they introduce new drawbacks. That is, since the obtained toner particles are perfectly spherical, the cleaning properties are poor, and the emulsifier or suspending agent remains in the toner particles.
Charging stability and blocking properties deteriorate. In general, in electrophotography, the fixing method for electrostatic images is a heat roll method, a pressure fixing method,
Various methods are known, such as the high frequency heating method and the flash method, but the heat roll method is currently the most common method. In the hot roll method, there are two methods: an oil coating method in which a mold release agent such as silicone oil is applied to the roll surface, and a material with excellent mold release properties such as Teflon or silicone rubber that does not use a mold release agent such as silicone oil. There is an oil-less method in which fixing is performed using a roll. In either case, offset development, in which toner melted by heat transfers to a hot roll and stains an image carrier such as paper, becomes a problem. Various methods have been proposed to prevent such offset development, one of which is a method of adding a resin mainly composed of polyolefin to the toner in order to increase the releasability of the toner. Even when producing toner using the suspension polymerization method, Japanese Patent Publication No. 13731/1983 states that ``The monomer that polymerizes to form the constituent molecules of a heated roller-fixed dry toner for electrostatic images is offset polymerized. ``The method is characterized by including a step of polymerizing in the presence of an inhibitor,'' and there is a method in which an offset inhibitor is added during polymerization. (Problems to be Solved by the Invention) However, in this method, polyolefins, which are offset waterproofing agents, disrupt the hydrophobic/hydrophilic balance of the polymerization system, resulting in a polymerization solution containing many aggregates. In addition, since polyolefin is more hydrophobic than the styrene-acrylic resin, which is a constituent molecule of the toner, it is localized in the core of the toner particle and is hardly present on or near the particle surface, so that the anti-offset effect is poor. Not expressed. The present invention solves these problems in conventional toner manufacturing methods, and provides excellent image density, resolution, and gradation, as well as particularly excellent cleaning properties, charging stability, blocking properties, and offset resistance. An object of the present invention is to provide a method for producing an electrophotographic toner suitable for dry development using an emulsion polymerization method, and which does not require a pulverization step. (Means and effects for solving the problems) The present invention emulsifies and disperses a polymerizable monomer in the presence of a colorant and/or magnetic powder and polymerizes it to produce a main resin component. A method for producing an electrophotographic toner in which toner particles are obtained by coagulating and dehydrating polymer particles in a polymerization solution so that they have a particle size suitable for the toner. An electronic device characterized in that an offset preventive agent is added to the toner until the polymerization rate is 90% or more, after the polymerization is completed and before coagulation, and/or after coagulation and before dehydration. This invention relates to a method for producing photographic toner. The 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 polymerizable monomer. During this polymerization, a colorant and/or magnetic powder and a polymerization initiator are present. In addition, toner property improvers such as charge control agents, fluidity improvers, and cleaning performance improvers, stabilizers for assisting emulsification and dispersion, and chain transfer agents 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. As the polymerization initiator, a water-soluble polymerization initiator or an oil-soluble polymerization initiator is used, and these may be used in combination. The polymerization initiator may be added after emulsification and dispersion, but it is preferable that the water-soluble polymerization initiator be dissolved in advance in an aqueous medium during emulsification and dispersion, and the oil-soluble polymerization initiator should be added to the polymerizable monomer. It is preferable to dissolve it in advance. 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. Further, a stabilizer may be used as necessary, and it may be added after the emulsification and dispersion, or may be dissolved in the 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 polymerization is preferably carried out at a temperature of 20 to 120°C after or while emulsifying and dispersing the above-mentioned, and in particular,
Preferably it is carried out at a temperature of 50-80°C. This 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 increases, the characteristics of the toner,
In particular, storage stability tends to be poor. Further, the polymer obtained by 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 the glass transition point 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 polymerization results in particles of about 3 μm or less. Next, materials used for polymerization will be explained. Examples of the polymerizable monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, and p-tert.
-butylstyrene, p-n-hexylstyrene,
p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, n-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlor Styrene and its derivatives such as styrene, unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride, vinyl acetate, vinyl propionate, Vinyl esters such as vinyl benzoate and vinyl butyrate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, pentyl acrylate, n-octyl acrylate, dodecyl acrylate, acrylic acid 2-ethylhexyl, stearyl acrylate,
2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylate α-methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl acid, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, acrylonitrile, methacrylate Acrylic acid or methacrylic acid derivatives such as lonitrile, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and optionally acrylic acid, methacrylate Acids such as maleic acid and fumaric acid can also be used. In addition, 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 vinyl ketone, N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinyl compounds such as N-vinylpyrrolidone and vinylnaphthalene salts can be used alone or in combination of two or more. Among these polymerizable monomers, styrene or styrene derivatives are
When used at 100% by weight, the toner has excellent fixing properties when copied onto paper using an electrophotographic copying device. Further, as the polymerizable monomer of the present invention, a compound having two or more polymerizable double bonds that serves 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 compounds having three or more vinyl groups can be used alone or as a mixture. The amount of the crosslinking agent used is preferably 0 to 20% by weight, particularly preferably 0 to 5% by weight, based on the total amount of polymerizable monomers. Water is mainly used as the aqueous medium used for emulsification and dispersion. The weight ratio of the polymerizable monomer to the aqueous medium is preferably 40/60 to 90/10. If this ratio is too small, emulsification and dispersion will be difficult, and if this ratio is too large, productivity will decrease. As the emulsifier, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant or a nonionic surfactant 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, alkylbenzene sulfonates 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 cationic surfactants 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 from 0.01 to the amount of polymerizable monomer.
It is preferably 10% by weight, particularly preferably 0.5 to 5% by weight. If the amount of emulsifier used is too small, stable emulsion polymerization will be difficult, and if the amount of emulsifier is too large, the moisture resistance of the resulting toner will be reduced. Stabilizers include water-soluble polymeric substances 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 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. In particular, when persulfate is used, sulfate anion radicals (SO ^- ₄ ), which serve as initiation active sites, exist on the surface of the monomer, and the particles are stabilized by the hydrophilic group and charge of SO ^- ₄ groups. It is easy to obtain an emulsion with a relatively uniform particle size. The water-soluble polymerization initiator described above may be used in combination with a reducing agent. As the reducing agent, commonly known reducing agents such as sodium metabisulfite and ferrous chloride can be used. The reducing agent does not necessarily need to be used, but when used, it is preferably used in an amount equal to or less than the amount of the water-soluble polymerization initiator. Examples of oil-soluble polymerization initiators include peroxides such as benzoyl peroxide and t-butyl perbenzoate, and azo compounds such as azobisisobutyronitrile and azobisisobutylvaleronitrile. It is preferable to use it by dissolving it in the body. The amount of polymerization initiator used is based on the polymerizable monomer.
It is preferably 0.01 to 10% by weight, preferably 0.1 to 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, degrading the properties of the toner. Examples of chain transfer agents include alkyl mercaptans such as t-dodecyl mercaptan, lower alkyl anthogens such as diisopropyl xanthogen, carbon tetrachloride, carbon tetrabromide, etc., and the amount thereof is 0 to 2% by weight based on the polymerizable monomer. Preferably used. 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 (CINo.azoec Blue3), Chrome Yellow (CINo.14090), Ultramarine Blue (C.
I.No.77103), DuPont Oil Red (CINo.
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, they are present in the toner at about 1-30% by weight, preferably 5-30% by weight.
It is used in proportions such that it is 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) using 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 colorant, 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 based on the grafted carbon black, particularly
It is preferably 30% by weight or less. Grafted carbon black is preferable because it has excellent dispersion stability during polymerization, but if the polymer component is too large,
When dispersed in a polymerizable monomer, the viscosity tends to become too high, reducing workability. 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 toner, and can also serve as a coloring agent. Preferred magnetic powders include, for example, iron such as magnetite or ferrite, or oxides or compounds of ferromagnetic elements such as nickel and cobalt. These magnetic powders are preferably powders with a particle size of 0.01 to 3 μm, and the surface of the magnetic powder is resin,
It may be treated with a titanium coupling agent, a silane coupling agent, a higher fatty acid metal salt, or the like. These magnetic substances can be contained in an amount of 20 to 80% by weight, preferably 35 to 70% by weight, based on the toner. Less than this amount may be used as a coloring agent. Furthermore, fluidity improvers, cleaning performance improvers, etc. can be used as necessary. these,
Although it can be present in the polymerization reaction system and present in the product toner, it is preferably externally added to the product toner afterwards. The content of each of these is preferably 0 to 3% by weight based on the toner of the present invention. Fluidity improvers include silane, titanium, aminium, calcium, magnesium, and magnesium oxides, or those obtained by hydrophobizing the above oxides with a titanium coupling agent or a silane coupling agent. , 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, by selecting the polymerizable monomer and colorant, the charge amount and charge polarity of the product toner can be freely adjusted. Additionally, a charge control agent may be used in the toner of the present invention in combination with the colorant. 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-t
Examples include aromatic acid derivatives such as -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 the main resin component is produced by polymerization, a coagulant is added to the resulting polymerization solution to coagulate particles containing the colorant and/or magnetic powder.
By appropriately agglomerating the polymer particles in the polymerization liquid, a toner having an average particle size larger than that of the polymer particles in the polymerization liquid, which is imperfectly spherical and does not require pulverization, is produced. suitable particles can be obtained. Here, the particle size distribution of the aggregated particles is 1 to 100μ
It is preferable to adjust it so that it becomes m, especially 3~
It is preferable to adjust the thickness to 70 μm, and the thickness should be adjusted to 5 to 70 μm.
It is most preferable to adjust the thickness so that the main component is 25 μm. It is preferable to adjust the average particle size to 9 to 15 μm. For the above adjustment, the amount of the coagulant is 0.1 to 5% of the weight of the emulsifier in the polymerization solution.
It is preferable to use twice as much, preferably 0.3 to 3 times.
If the amount of coagulant used is too small, the coagulation 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. Since incompletely spherical toner particles are obtained through this coagulation step, the toner particles have excellent cleaning properties. Further, since the emulsifier is also removed by this coagulation step, blocking resistance and charging stability are also improved. In this coagulation step, the polymerization solution and coagulant can be mixed by a method such as dropping the polymerization solution little by little into the coagulant aqueous solution while stirring, or mixing the coagulant aqueous solution and the polymerization solution at a fixed ratio. . In this coagulation process, the temperature is not particularly limited, but it is preferably from room temperature to 150°C. In particular, it is preferable to carry out (along with heat treatment) at a temperature above the softening point of the main resin component, and below the softening point. When coagulation is carried out at high temperature, it is particularly preferable to subsequently heat the salting-out solution to a temperature equal to or higher than the softening point of the polymer (heat treatment operation). Such heat treatment increases the bulk density of the particles of the main resin component, improving moisture resistance, offset resistance, and durability. It is also possible to add a large amount of coagulant to the polymerization liquid in the coagulation process to obtain large coagulates, which are then pulverized to a particle size suitable for toner. This method has the effect of uniformly dispersing additives in the resin, but due to the pulverization, the toner has a shape closer to that of the pulverized toner than the toner according to the present invention, and therefore has poor cleaning properties and toner fluidity. inferior to On the other hand, in the present invention, the particles obtained by coagulation can be made into toner as is or by just being classified, and the shape of the toner particles is different from the asymmetric amorphous shape like pulverized toner. different,
Also, since it is not perfectly spherical, but imperfectly spherical,
Excellent cleaning properties. Examples of the coagulant 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 coagulating agents are magnesium sulfate, aluminum sulfate, barium chloride, magnesium chloride, calcium chloride, sodium chloride, and/or a mixture of these and an inorganic acid. be. These coagulants are preferably used as a 0.1-1.0% by weight aqueous solution, particularly a 0.1-5% by weight aqueous solution. After coagulation, toner particles can be obtained by centrifugal dehydration, further washing, drying and, if necessary, classification. Washing at this stage is preferable in order to completely remove the emulsifier adhering to the particles, thereby improving the charging stability and blocking property as well as the above-mentioned coagulation. Washing is preferably carried out with warm water at 40-60°C. Note that the post-solidification heat treatment operation may be inserted during the washing step or between two or more washing steps. In addition, in the present invention, the dispersion of the offset inhibitor can be prepared (a) during polymerization until the polymerization rate is 90% by weight or more, (b) after the end of polymerization and before coagulation, and/or (c) ) It is essential to add it after coagulation and before dehydration. The dispersion of the anti-offset agent is added in at least one of the steps (a), (b) and (c), and may be added multiple times. When the above-mentioned dispersion of the offset inhibitor is added from the time when the polymerization rate in polymerization reaches 90% by weight until after the polymerization is completed and before coagulation, the offset inhibitor is not present in the core of the polymerized particles at the end of the polymerization. is present between the polymer particles and on the surface of the particles obtained by coagulation, and a dispersion of an offset inhibitor is added after coagulation. In this case, the anti-offset agent adheres to the surface of the particles obtained by coagulation. On the other hand, if a dispersion of an offset inhibitor is added when the polymerization rate is earlier than 90% by weight, especially at the beginning of polymerization, the offset inhibitor will be present in the core of the polymer particles at the end of polymerization. Even if particles obtained by coagulating this are used as a toner, the effect of preventing offset is extremely small. Further, when the offset inhibitor is added after the completion of solidification, it is preferably added before the heat treatment described above. This is because the anti-offset agent is more likely to adhere to the particle surface if the heat treatment is performed before the heat treatment than if it is performed after the heat treatment. In the present invention, the offset inhibitor dispersion is a liquid in which the offset inhibitor is dispersed in the form of fine particles in water as a continuous phase. Here, as the offset preventive agent, one is used that has an offset preventive effect and is dispersible in water, such as various natural waxes such as carnauba wax, hydrogenated castor oil, and low molecular weight olefin polymers. Although used in the present invention, preferably low molecular weight olefin polymers are used. This low molecular weight olefin polymer is an olefin polymer or a copolymer of olefin and a monomer other than olefin, and has a low molecular weight.
Here, olefins include ethylene, propylene, butene-1, etc., and monomers other than olefins include acrylic esters, methacrylic esters, etc. As such a low molecular weight olefin polymer, for example, Japanese Patent Application Laid-Open No. 55-153944
The polyalkylene described in the publication, JP-A-Sho
A low molecular weight olefin copolymer described in Japanese Patent No. 50-93647 can be used. Also,
Two or more of the above-mentioned offset inhibitors may be used in combination. 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 chemistry, but it is generally 1000 to 45000 in weight average molecular weight (Mw), preferably 1000 to 45000.
2,000 to 6,000°C, and preferably has a softening point of 100 to 180°C, particularly preferably 130 to 160°C. It is preferable that the offset preventive agent in the dispersion has an average particle size of 5 μm or less and does not contain particles with a particle size exceeding 20 μm. If the particle size is too large, some of the toner particles obtained by the present invention may not contain an offset inhibitor. In addition, in the above dispersion, the ratio of the offset prevention agent to water is 5/5 to 5/5 by weight of the former/latter.
Preferably it is 9/1. If this ratio is too small, the stability of the dispersion liquid will be reduced, and if this ratio is too large, the processing efficiency will be reduced. There are no particular limitations on the method for producing the above dispersion. For example, a method in which a solid or liquid offset preventive agent is dispersed in water using a machine such as a homomixer, a homogenizer, a disperser, or an ultrasonic disperser, or a method in which a monomer capable of polymerization reaction is dispersed and polymerized in water. There is. In the former dispersion method, an anionic or nonionic surfactant may be further used in order to improve the stability of the dispersion liquid and make the particles smaller. The type and amount of the surfactant vary depending on the anti-offset agent to be dispersed, but the amount is preferably 10% by weight or less based on the anti-offset agent. If the amount of surfactant is too large, a large amount of surfactant will remain in the final toner product, making the toner hygroscopic and having an adverse effect on storage stability and charging characteristics. Further, when the resin to be dispersed is solid at room temperature, it is preferable to heat the resin to a temperature higher than its softening point or to plasticize it by adding a small amount of an organic solvent. On the other hand, the latter polymerization method is divided into emulsion polymerization method and suspension polymerization method, but emulsion polymerization method is preferable because it produces finer particles. The emulsion polymerization method is carried out by emulsifying and dispersing a polymerizable monomer in an aqueous medium containing an emulsifier and polymerizing it. The emulsifier used in this case is preferably used in an amount of 10% by weight or less based on the offset inhibitor, similar to the above-mentioned surfactant. The negative effects of too much emulsifier are similar to those for surfactants described above. In the method of the present invention, there is no particular limit to the amount of the anti-offset agent dispersion added, but the toner should contain 0.1 to 30% by weight of the anti-offset agent. If it is less than 0.1% by weight, no offset prevention effect will be achieved, and if it exceeds 30% by weight, image quality, including image strength, tends to deteriorate significantly. The amount of the above dispersion liquid is determined based on the weight of the polymer particles obtained by polymerization or the particles obtained by coagulation and the amount of offset preventive agent to be contained so that the offset preventive agent is within the above range. Added as a guide. 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 specification No. 2874065,
The powder cloud method described in U.S. Patent No. 2,221,776, the touch-down development method described in U.S. Pat. No. 3,166,432, and JP-A-Sho
It can be used in the so-called jumping method described in Publication No. 55-18656, the so-called bipolar magnetic toner method in which the necessary toner charge is obtained by frictional charging of magnetic toner produced by a pulverization method as a carrier, etc. can. In addition, the toner obtained by the present invention can be used not only by a fixing method using a hot roll method, but also by a flash method,
Other fixing methods such as oven methods can also be used. 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. (Example) Next, the present invention will be explained in detail based on an example.
The present invention is not limited to this. In addition,
In the examples, "%" means "% by weight" unless otherwise specified. Example 1 (1) Production of emulsion polymerization solution In the stainless steel beaker of step 3, 100 g of grafted carbon (Graft Carbon GP-E-2, manufactured by Ryoyu Kogyo Co., Ltd.) was mixed with 400 g of styrene as a polymerizable monomer and acrylic acid. 120 g of butyl and 0.6 g of t-dodecyl mercaptan as a chain transfer agent,
Mixing and dispersion was performed using a homomixer at 3000 rpm for 30 minutes. Next, ion exchange water is added to this carbon dispersion.
1420g of sodium dodecylbenzenesulfonate 12 which is an anionic surfactant as an emulsifier.
g. Nonionic surfactant Nonipol PE
3 g of -68 (oxypropylene-oxyethylene block polymer manufactured by Sanyo Chemical Industries, Ltd.), 3 g of Neugen EA170 (polyoxyethylene glycol nonyl phenyl ether manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 12 g of ammonium persulfate as a polymerization initiator. Add the dissolved aqueous solution and mix further with a homomixer.
Emulsification was carried out at 3000 rpm for 30 minutes to obtain a black pre-emulsion. Next, the black pre-emulsion was transferred to a four-necked separable flask equipped with a stirrer, a nitrogen inlet, a thermometer, and a 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 99.5%. 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 86,000 and a number average molecular weight (Mn) of 30,000. (2) Production of offset preventive agent dispersion Add low molecular weight polypropylene (Viscol 660P, manufactured by Sanyo Chemical Industries, Ltd.) to the autoclave in step 3.
750g, sodium dodecylbenzenesulfonate (anionic surfactant) 15g and ion exchange water
2235 g was added, the container was sealed, and heated under pressure to 154° C., which is about 20° C. higher than the melting point of Viscol 660P. The stirring speed was increased to 1000 rpm and kept warm for 30 minutes. Cool while continuing stirring,
The dispersion was taken out. When the particle size was measured using a Coulter counter, there were no particles larger than 5μ.
It was found to be a dispersion of particles with an average particle size of 1.2μ. (3) Coagulation step, final step Emulsion 1 produced in (1) and 24 ml of the dispersion produced in (2) were mixed. At this time, no phenomena such as coagulation and precipitation occurred. Furthermore, the above mixture was heated to 100°C and a 0.3% aqueous solution of MgSO ₂ was added.
While sufficiently stirring the aqueous solution and maintaining the temperature of the aqueous solution at 30° C., the solution was uniformly added dropwise over about 30 minutes to effect salting out. Furthermore, it was kept at this temperature for 30 minutes, and then cooled to room temperature. Next, this slurry was dehydrated using a centrifugal dehydrator, and then washed three times with warm water at 50°C. Next, it was dried in a dryer at 30 to 35°C to obtain a toner. When the particle size of the obtained toner was measured using a Coulter counter, the particle size was 1 to 50 μm, and the average particle size was 13 μm. Furthermore,
When the glass transition point (Tg) was measured using a differential scanning calorimeter, it was 73°C. This toner was further classified into 5 to 25 μm using a zigzag classifier (100MZR, manufactured by Alpin).
The yield was 90%. In addition, in the following Examples and Comparative Examples, the particle size and average particle size were measured using a Coulter counter.
The glass transition point was determined using a differential scanning calorimeter, and the classification was performed using a zigzag classifier. Example 2 The same emulsion polymerization solution and offset inhibitor dispersion as used in Example 1 were used. Emulsion polymerization solution 1
While thoroughly stirring and maintaining the temperature of the aqueous solution at 30°C, it was uniformly added dropwise to a 1% aqueous solution 2 of MgSO ₄ heated to 30°C over about 30 minutes, and solidified. While stirring the coagulated emulsion polymerization solution, 24 ml of the offset inhibitor was added dropwise over 10 minutes so that the offset inhibitor was uniformly salted out. Furthermore, it was kept at this temperature for 30 minutes, and then cooled to room temperature. Then,
This slurry was subjected to centrifugal dehydration, washing and drying in the same manner as in Example 1 to obtain a toner. The particle size of the obtained toner was 1 to 50 μm, the average particle size was 14 μm, and the glass transition point (Tg) was 73°C. Example 3 A dispersion of modified polyethylene wax (Suncoat manufactured by Sanyo Chemical Co., Ltd.) was produced in the same manner as in Example 1 (2). Add 18 ml of the above dispersion to the emulsion polymerization solution 1 of Example 1 (1), perform the same coagulation and final steps as in Example 1, and obtain particles with a particle size of 2 to 100 μm, an average particle size of 15 μm,
The glass transition point (Tg) was 73°C. Furthermore, classification was performed to obtain toner having a size of 5 to 25 μm. Example 4 (1) Production of emulsified dispersion monopolymerization liquid In the stainless steel beaker of step 3, 100 g of grafted carbon (Graft Carbon GP-E-2, manufactured by Ryoyu Kogyo Co., Ltd.) was mixed with 400 g of styrene as a polymerizable monomer, 120 g of butyl acrylate, 10.4 g of azobisisobutyronitrile as a polymerization initiator, and t-dodecyl mercaptan as a chain transfer agent.
0.6 g was mixed and dispersed using a homomixer at 3000 rpm for 30 minutes. Next, this dispersion was mixed with 1420 g of ion-exchanged water, 12 g of sodium dodecylbenzenesulfonate, an anionic surfactant as an emulsifier, and Nonipol PE-68 (oxypropylene-oxyethylene block manufactured by Sanyo Chemical Industries, Ltd.), a nonionic surfactant. An aqueous solution containing 3 g of Polymer) and 3 g of Neugen EA170 (Daiichi Kogyo Seiyaku Co., Ltd. polyoxyethylene glycol nonyl phenyl ether) 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 four-necked separable flask equipped with a stirrer, a nitrogen inlet, a thermometer, and a condenser, and the flask was polymerized at 70°C for 5 hours under a nitrogen stream, and then cooled. A polymerization solution was obtained. The polymerization rate at this time was 99.5%. 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 65,000 and a number average molecular weight (Mn) of 30,000. (2) Coagulation step, final step Emulsion 1 produced in this way and Example 1
24 ml of the dispersion prepared in the same manner as in (2) was added, and the coagulation and final steps were carried out in the same manner as in Example 1.
The particle size was 3 to 120 μm, the average particle size was 17 μm, and the glass transition point (Tg) was 73°C. Further classification,
A toner of 5 to 25 μm was obtained. Comparative Example 1 (No offset inhibitor added) The emulsion polymerization solution produced in Example 1 (1) was coagulated without adding an offset inhibitor, and the same final process and classification were performed to obtain a toner. . Comparative Example 2 (Polymerization in the presence of offset inhibitor) (1) Production of emulsion polymerization solution Grafted carbon 100g, styrene 400g,
120 g of butyl acrylate, 0.6 g of t-dodecylmercaptan, and 12.4 g of low molecular weight polypropylene (Viscol 550P, manufactured by Sanyo Chemical) were mixed and dispersed using a homomixer at 3000 rpm for 30 minutes. Next, 24 g of sodium dodecylbenzenesulfonate and 6 nonionic surfactant Nonipol PE-68 (manufactured by Sanyo Chemical Co., Ltd.) were added to 1300 g of ion-exchanged water.
g, also the nonionic surfactant Noigen EA-
170 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and an aqueous solution containing 12 g of ammonium persulfate as a polymerization initiator were added, and the mixture was emulsified by stirring at 3000 rpm using a homomixer for an additional 30 minutes to obtain a black pre-emulsion. This black pre-emulsion was transferred to a four-neck separable flask (No. 3), polymerized at 70° C. for 5 hours under a nitrogen stream, and then cooled to obtain an emulsion polymerization solution. The polymerization rate at this time was 99.5% or more, and the molecular weight of the polymer determined in the same manner as in Example 1 was a number average molecular weight of 21,000 and a weight average molecular weight of 68,000. (2) Coagulation process, final process The coagulation process and final process were carried out under the same conditions as in Example 1 (1% MgSO ₄ aqueous solution, 30°C) without adding an offset inhibitor to the emulsion polymerization solution produced in (1) above. A final step was performed and further classification was performed to obtain a toner. Using the toners obtained in Examples 1 to 4 and Comparative Examples 1 and 2, a plain paper copying machine (Konishiroku Photo Industry Co., Ltd.) was used.
The electrophotographic toner properties were tested using U-Bix 1600 (manufactured by Co., Ltd.). However, each toner contains hydrophobic silica (R manufactured by Nippon Aerosil Co., Ltd.) as a fluidity improver.
-972) and zinc stearate were externally added to the above toner in an amount of 0.6% and 0.1%, respectively.
The test results are shown in Table 1.

【table】

[Table] Example 5 (1) Production of emulsion polymerization solution Styrene was added as a polymerizable monomer to 100 g of grafted carbon (Graft Carbon GP-E-2, manufactured by Ryoyu Kogyo Co., Ltd.) in the stainless steel beaker of step 3. 360 g, butyl methacrylate 180 g, methacrylic acid 6 g and t-dodecyl mercaptan 0.6
g was mixed and dispersed using a homomixer at 3000 rpm for 30 minutes. Next, 18 g of sodium dodecylbenzenesulfonate and nonionic surfactant Nonipol PE-68 (manufactured by Sanyo Chemical Industries, Ltd.) were added to 1470 g of ion-exchanged water.
An aqueous solution containing 4 g of ammonium persulfate, 9 g of ammonium persulfate, and 10 g of hydrogen peroxide (30%) was added to a homomixer and emulsified at room temperature and 3000 rpm for 30 minutes to obtain a black pre-emulsion. Transfer this black pre-emulsion into a four-necked separable flask and heat it at 70°C under a nitrogen stream.
After polymerizing for 5 hours, the mixture was cooled to obtain an emulsion polymerization solution. The polymerization rate at this time is 99.5% or more,
The molecular weight of the polymer determined in the same manner as in Example 1 was 96,000 for Mw and 39,000 for Mn. (2) Coagulation step, final step Using the emulsion prepared in (1), Examples 1 and 2
Low molecular weight polypropylene (viscol) used in
660P) and the emulsion of the modified polyethylene wax (Suncoat) used in Example 3, the same coagulation and final steps were carried out to obtain a toner. Furthermore, classification was performed and Examples 1 to 3
A similar test was conducted. Test conditions and test results are shown in Table 2.

【table】

[Table] Note that the evaluation of the electrophotographic properties in the above Examples and Comparative Examples was performed as follows. (a) Resolution: Copies were made on plain paper using the electrophotographic society test chart No. 1 and the respective developers. A comparative evaluation was made to see if the copied 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:
The toner was left for 72 hours under conditions of 50° C. and 95% humidity, and it was determined whether or not the toner was blocked, and evaluated as ○: excellent, ×: poor. (e) Charge stability: Each prepared developer was stirred in a copying machine, the amount of charge was measured at regular intervals, and the evaluation was made based on the change in the amount of charge. ○: Excellent ×: Inferior. (f) Durability: Using a copying machine, each developer was tested at a temperature of 30℃ and a humidity of 80% RH for 10,000 hours.
Continuous copying was performed. The toner scattering that occurs at this time was investigated and judged based on the following evaluation. ◎: No toner scattering ○: Some toner scattering is observed △: A lot of toner scattering ×: A large amount of toner scattering occurs (g) Hygroscopicity: Each prepared toner was heated at 25°C and humidity at 98°C. The weight was left to stand for 24 hours under the following conditions, and the weight increase after humidification is expressed as a percentage of the weight before humidification. (h) Offset resistance: Remove the fixing section of a plain paper copying machine (U-Bix1600 manufactured by Konishiroku Photo Industry Co., Ltd.) to obtain an unfixed toner image, and use the Teflon coated roll on the upper side and the silicone rubber coated roll on the lower side. Using a fixing test device that can change the temperature of the upper roll, fixing was carried out at a linear speed of 70 mm/sec and an inter-roll pressure of 0.5 Kgf/cm, and those with no offset were evaluated as ○, and those with offset were evaluated as ×. . (Effects of the Invention) The present invention provides a film that is excellent in resolution, image density, gradation, cleaning performance, charge stability, and blocking property, and that does not cause offset phenomenon when fixed by a hot roll method, and is suitable for dry development. An electrophotographic toner can be obtained.

Claims (1)

[Claims] 1. A polymerizable monomer is emulsified and dispersed in the presence of a colorant and/or magnetic powder and polymerized to produce a main resin component, and the polymer particles in the obtained polymerization liquid have a particle size suitable for toner. A method for producing toner for electrophotography in which toner particles are obtained by coagulating and dehydrating the toner particles, in which a dispersion of an offset inhibitor is polymerized at a polymerization rate of 90%.
An electrophotographic toner characterized by containing an offset preventive agent in the toner by adding at least % by weight until the end of polymerization, after the end of polymerization and before coagulation, and/or after coagulation and before dehydration. manufacturing method.