JPH059024B2 - - 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. 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 produced by applying mechanical impact force to crush the dispersion to a desired particle size, and if necessary, further classifying it to form a toner. 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. In addition, Japanese Patent Publication No. 14895/1983, Japanese Patent Application Publication No. 1987-
A method for producing toner by suspension polymerization is proposed in Japanese Patent No. 53756 and the like. When using 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. In addition, if a resin that is easily crushed is used, it will be crushed in the developing device and become fine toner, which will cause image fogging and dirt inside the machine in the future. 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 of the surface of the photoreceptor and contamination of the surface of the photoreceptor. 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, charging stability and blocking properties are reduced. Further, in electrophotography, the toner image is fixed after development and transfer, but conventionally, the transferred toner image is melted and fixed in an oven.
The so-called oven fixing method was the mainstream. but,
In recent years, from the viewpoints of downsizing, high-speed copying, and energy saving of copying machines, a shift has been made to a so-called heat roll fixing method in which fixing is performed using a heated roller. In the conventional oven fixing method, an oligomer resin having a molecular weight of 10,000 or less is used as the toner fixing resin because it needs to melt quickly in the oven. However, in the hot roll fixing method, when such oligomers are used as the fixing resin, offset development occurs, in which part of the toner adheres to the surface of the fixing roll during fixing and stains other paper, making it impractical for practical use. cannot be provided. In order to prevent this offset development, there is a method of applying a mold release liquid such as silicone oil to the fixing roll, but it is mechanically difficult to apply it uniformly, and the mold release liquid is heated. There are problems such as generating odor and increasing the size of the device. In order to prevent offset in terms of fixing resin, it is effective to increase the molecular weight of the resin. In the case of polystyrene, which is commonly used as a resin, if the average molecular weight is 50,000 or more, preferably 100,000 or more, heating No offset to the roll at all. However, when such a high-molecular-weight resin is used as a fixing resin, there is a drawback that the toner's fixability to paper or sheets is extremely poor, and the fixed image may be bent or folded.
It has the disadvantage that it easily peels off due to friction, etc. The present invention solves the above-mentioned problems and provides an electrophotographic image suitable for the hot roll fixing method, which has excellent image density, resolution, and gradation, and has particularly excellent low-temperature fixing properties and offset resistance. The purpose of the present invention is to provide a method for producing toner for use in other applications. (Means for solving the problems) The present invention is based on the general formula: 2-polystyryl represented by [In the formula, R ₁ represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, R ₂ represents a hydrogen atom or a methyl group, and n represents an integer of 10 to 200] Producing a main resin component by emulsion polymerizing ethyl acrylate or methacrylate and an unsaturated monomer copolymerizable with these in the presence of a colorant and/or magnetic powder, and salting out the obtained emulsion polymerization liquid. The present invention relates to a method for producing an electrophotographic toner characterized by: 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 can be added. In addition, toner property improvers such as offset inhibitors, charge control agents, fluidity improvers, and cleaning performance improvers, stabilizers for assisting emulsification and dispersion, and chain transfer agents may be present as appropriate. 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 the polymerizable monomer 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 above-mentioned emulsification and dispersion, or may be used by being dissolved in the aqueous medium in advance. The 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. Emulsion polymerization is preferably carried out at a temperature of 20 to 120°C, particularly 50 to 80°C, after or while emulsifying and dispersing. 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 tends to decrease. 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, blocking resistance tends to decrease, and if it is too high, 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 in the present invention will be explained. General formula: [In the formula, R ₁ represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, R ₂ represents a hydrogen atom or a methyl group, and n represents an integer of 10 to 200]. Styrylethyl acrylate or methacrylate is generally referred to as a large molecular monomer (macromonomer), such as Chemlink 4500, 4500B from Sartomer,
It has been commercialized as 4545B etc. This Chemlink 4500 has the above general formula in which R ₁ is C ₄ H ₉ and R ₂ is
A compound which is CH ₃ and n is about 120,
It is a granular solid with a narrow molecular weight distribution of 13,000. In addition, Chemlink 4545B has a molecular weight of 4500
It is. By strongly polymerizing this monomer in combination with other copolymerizable monomers, a copolymer having a high molecular weight side chain based on 2-polystyrylethyl acrylate or methacrylate can be obtained. When such a copolymer is used as a resin component of an electrophotographic toner, it exhibits excellent low-temperature fixing properties, wide range of offset resistance, and high image quality. The amount of the large molecular monomer used is 10 to 98% by weight, preferably 40 to 80% by weight, and if it is less than 10% by weight, the low temperature fixing properties and wide offset resistance that are the objects of the present invention cannot be achieved. Not shown. Moreover, if it exceeds 98% by weight, a sufficient copolymer cannot be obtained. Other components that can be copolymerized with the above large molecular monomers include styrene and its derivatives, ethylene,
Ethylenically unsaturated monoolefins such as propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinylidene bromide, vinyl halides such as vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, Vinyl esters such as vinyl butyrate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl 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-octyl methacrylate, dodecyl methacrylate, methacrylate α-methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl acid, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, acrylonitrile, Methacrylonitrile, acrylamide, methacrylamide, and in some cases, acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. 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 isopropenyl ketone, N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, N- such as N-vinylpyrrolidone
Vinyl compounds, vinylnaphthalene salts, etc. can be used alone or in combination of two or more. 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 dimethacrylate, and trimethylolpropane triacrylate;
N,N-divinylaniline, divinyl ether,
Divinyl compounds such as 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 0 to 20% by weight, especially 0% by weight based on the total amount of polymerizable monomers.
Preferably it is 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 in weight ratio of the former/latter. When this ratio is too small, emulsion polymerization becomes difficult, and when this ratio is too large, the yield decreases. 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 charged toner, and a cationic surfactant when producing a positively charged 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 alkylnaphthalenesulfonic acids. salts, 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 -Oxitipropylene 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, especially 0.5-5% by weight is preferred. 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, and 2,2'-azobis(2-amidinovaleric acid). (propane) dihydrochloride, t-butyl hydroperoxide, cumene hydroperoxide, etc. can be used.
In particular, when persulfates are used, the sulfate anion radical (SO ₄ ^- ) serves as the initiating active site.
is present on the surface of the monomer, and the particles are stabilized by the hydrophilic group of the SO ₄ ^- group and the electrostatic charge, making it easy to obtain an emulsion having a relatively uniform particle size. The amount used is 0.01 to 10% by weight, especially 0.1 to 10% by weight based on the polymerizable monomer.
Preferably it is 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, deteriorating the properties of the toner. As a polymerization initiator, oil-soluble polymerization initiators such as peroxides such as benzoyl peroxide and t-butyl perbenzoate, and azo compounds such as azobisisobutyronitrile and azobisisobutylvaleronitrile are used in combination. be able to. 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, commonly known reducing agents such as sodium metabisulfite and ferrous chloride can be used. It is not necessary to use a reducing agent, but if you do,
It is preferable to use it 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 Blue 3), 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 (CI No. 52015), Phthalocyanine Blue (CI No. 74160), Malachite Green Oxalate (CI No. 42000), Lamp Black (CI No. 77266), Rose Bengal (CI No. 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. Examples of surface treatments 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 based on the grafted carbon black.
It is preferably 30% by weight or less. 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 a polymerizable monomer. Work efficiency decreases. 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 double as a colorant. Preferred magnetic powders include, for example, oxides or compounds of iron such as magnetite and ferrite, or ferromagnetic elements such as nickel and cobalt.
These magnetic powders are preferably in powder form with 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, etc. . 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. Anti-offset agents are used if necessary. The offset inhibitor can be present in the system in various forms during polymerization and can be included in the toner product. Alternatively, the anti-offset agent can be added later to the toner of the present invention in which it is not present. As the offset inhibitor, various natural waxes such as carnauba wax, hydrogenated castor oil or low molecular weight olefin polymers can be used 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, as the olefin, ethylene, propylene, butene-
There are 1st grade monomers other than olefin,
There are 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 that can be used in the present invention may be within the concept of low molecular weight in ordinary polymer chemistry, but generally the weight average molecular weight (Mw) is 1000 to 45000, Preferably it is 2000-6000. The low molecular weight polyolefin polymer that can be used in the present invention preferably has a softening point of 100 to 180°C, particularly 130 to 160°C. The amount of the low molecular weight olefin polymer that can be used in the present invention is not particularly limited, but 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 low molecular weight olefin polymer is too small, the offset prevention effect due to its addition will not be achieved.
If it exceeds 30% by weight, gelation may occur during the polymerization reaction. Furthermore, fluidity improvers, cleaning performance improvers, etc. can be used as necessary. these are,
Although it can be present in the polymerization reaction system and 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. Examples of 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. , 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 suitably used in the present invention include Spiron Black TRH and Spiron Black TPH.
Azo dyes such as (manufactured by Hodogaya Chemical Co., Ltd.), p-fluorobenzoic acid, p-nitrobenzoic acid, 2,4-di-t
Examples include aromatic acid derivatives such as -butylsalicylic acid, tin compounds such as dibutyltin oxide, and dioctyltin 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 cause salting out. Salting out is preferably adjusted so that the particle size distribution of the aggregated particles is 1 to 100 μm, particularly 3 to 70 μm, and most preferably adjusted so that particles of 5 to 25 μm are the main component. preferable. The average particle size is preferably adjusted to 9 to 15 μm.
For the above adjustment, it is preferable to use the salting-out agent in an amount of 0.1 to 5 times, preferably 0.3 to 3 times, the weight of the emulsifier in the emulsion polymerization solution. If the amount of salting-out agent used is too small, salting-out curing 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 the glass transition point of the main resin component, particularly preferably from 20°C higher than the glass transition point to 150°C or lower. Alternatively, in the case of salting out at a temperature below the glass transition point, it is preferable to provide a step of heat treatment at a temperature above the glass transition point. Such heat treatment increases the bulk density of the particles of the main resin component, improving moisture resistance, offset resistance, and durability. In the salting-out process, it is possible to add a large amount of salting-out agent to the emulsion polymerization solution to obtain a large coagulate, which is then pulverized to a particle size suitable for toner. Compared to toner, it has the effect that additives can be uniformly dispersed in the resin, but due to the pulverization, it takes a shape closer to the pulverized toner than the toner according to the present invention, so it has poor cleaning properties. Toner fluidity is poor. On the other hand, in the method of the present invention, the particles obtained by salting out can be made into toner as is or by just being classified, and the shape of the toner particles can be asymmetrical like the pulverization method toner. It is completely different from a spherical shape, and is not perfectly spherical, but 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. This is what I did. These salting-out agents are 0.1-10% by weight
It is preferably used as an aqueous solution, especially a 0.1-5% 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 dispersant 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 40-60°C. Note that the above 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 phenomenon method described in US Pat. No. 2,618,552;
The magnetic brush method described in Publication 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 the JP-A-55
The so-called jumping method described in Japanese Patent No. 18656, the so-called microtoning method using magnetic toner produced by a powder method as a carrier, and the so-called bipolar method in which the necessary toner charge is obtained by frictional charging between magnetic toners. It can be used in magnetic toner methods, etc. 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 heated 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, particles in the emulsion polymerization liquid are appropriately aggregated by salting out the emulsion polymerization liquid,
It has a larger average particle size than the particles in the emulsion polymerization solution,
It is possible to obtain resin particles that are imperfectly spherical and do not require pulverization and are suitable for toner. 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, since the toner obtained by the present invention has a block polymer skeleton as its main resin component, it exhibits low-temperature fixing properties and a wide range of offset resistance. (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.
shall mean. Example 1 (1) Production of emulsion polymerization solution Chemlink 4500 was added to the stainless steel beaker in step 3.
(manufactured by Sartomer, molecular weight Mw 13000) 420g dissolved in 180g n-butyl methacrylate and grafted carbon (Grafted Carbon GP
-E-2 (manufactured by Ryoyu Kogyo Co., Ltd., consisting of 30% carbon, 30% resin, and 40% styrene), 100 g, low molecular weight polypropylene (Viscol 550P, manufactured by Sanyo Chemical Industries, trade name) 12 g, and chain transfer As an agent, 0.6 g of t-dodecyl mercaptan was mixed and dispersed using a homomixer at 3000 rpm for 30 minutes. Next, ion exchange water is added to this carbon dispersion.
Add sodium todecylbenzenesulfonate 12, an anionic surfactant, as an emulsifier to 1300g.
g. Nonionic surfactant Nonipol PE
-68 (manufactured by Sanyo Chemical Industries, Ltd., trade name, polyoxypropyl-oxyethylene block polymer)
3 g of Neugen EA190 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name, polyoxyethylene glycol nonyl phenyl ether) and an aqueous solution containing 12 g of ammonium persulfate as a polymerization initiator were added, and the mixture was further mixed with a homomixer at 3000 rpm for 30 minutes. , and emulsified 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 99.9% or more. The molecular weight of the polymer was measured by gel chromatography using a standard polystyrene calibration curve, and the weight average molecular weight (Mw) was 120,000 and the number average molecular weight (Mn) was 35,000. (2) Salting out step, final step The above emulsion polymerization solution 1 was uniformly dropped into a 3% magnesium sulfate aqueous solution 1 heated to 60° C. over about 30 minutes with sufficient stirring, and salted out. The resulting slurry was transferred to an autoclave and heated to 120
Heat treated at ℃ for 30 minutes. Next, this slurry was dehydrated using a centrifugal dehydrator, and then washed three times with warm water at 50°C. After that, put it in the dryer for 30~
It was dried at 35°C to obtain a toner. The particle size of the obtained toner was measured using a Coulter counter, and the particle size was 4 to 60 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 71℃. When this toner was further classified into 5 to 25 μm using a zigzag classifier (100MZR, manufactured by Alpin), the yield was 92% of that before classification. Also 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 measured using a differential scanning calorimeter, and the classification was performed using a zigzag classifier. Example 2 In the same manner as in Example 1, 210 g of Chemlink 4500 (manufactured by Sartomer), 210 g of styrene, 180 g of n-butyl methacrylate, and grafted carbon (Graft Carbon GP-E-2, manufactured by Ryoyu Kogyo Co., Ltd.) were prepared. 100g
and low molecular weight polypropylene (Viscol 550P,
An emulsion polymerization solution was obtained in the same manner as in Example 1 using 12 g of Sanyo Chemical Industries, Ltd. (other components were the same as in Example 1). The polymerization rate was 99.9% or more, and the molecular weight of the polymer was Mw = 150,000 and Mn = 37,000. Further, salting out and heat treatment were performed in the same manner as in Example 1 to obtain a dried toner. The obtained toner had a particle size of 3 to 70 μm, an average particle size of 14 μm, and a Tg of 70°C. Furthermore, the yield upon classification was 90%. Comparative Example 1 In the same manner as in Example 1, 420 g of styrene, 180 g of n-butyl methacrylate, and grafted carbon (Graft Carbon GP-E-2, manufactured by Ryoyu Kogyo Co., Ltd.)
100g and low molecular weight polypropylene (viscol)
An emulsion polymerization solution was obtained in the same manner as in Example 1 using 12 g of 550P (manufactured by Sanyo Chemical Industries, Ltd.) (other components were the same as in Example 1). The polymerization rate is 99.9% or more, and the molecular weight of the polymer is Mw = 110000, Mn =
It was 33000. Further, salting out and heat treatment were performed in the same manner as in Example 1 to obtain a dried toner. The obtained toner had a particle size of 2 to 70 μm, an average particle size of 15 μm, and a Tg of 72°C. Furthermore, the yield upon classification was 85%. Comparative Example 2 (1) Synthesis of resin Chemlink 4500 (manufactured by Sartomer) 700 was placed in a four-necked flask equipped with a stirrer, inert gas inlet, thermometer, condenser, and dropping funnel.
g, 300 g of n-butyl methacrylate, and 1000 g of toluene were charged, and the temperature of the flask was raised to 100°C. Next, 6g of azobisisobutyronitrile
A solution of 200 g of toluene was uniformly added dropwise over 2 hours. After completing the dropwise addition, increase the reaction temperature to 110℃.
Raise the temperature to ℃ and keep warm for 4 hours. The polymerization rate of this resin was 99% or more. The solvent was removed from the obtained polymerization solution using a vacuum desolvation device to obtain a solid resin. The resulting resin has a Tg of 74℃ and a Mw of
100,000, and Mn was 30,000. (2) Manufacture of toner 900g of the above resin Spiron Black TRH (manufactured by Hodogaya Chemical Co., Ltd.)
30 g of carbon black #44 (manufactured by Mitsubishi Kasei), 50 g of low molecular weight polypropylene (manufactured by Sanyo Kasei, Viscoel 55P), and 20 g were weighed and mixed in a super mixer. Furthermore, the mixture was melt-kneaded using a twin-screw kneader. Subsequently, after coarse pulverization using a super mixer and a hammer mill and fine pulverization using a jet mill, the particles were adjusted to a particle size of 5 to 25 μm using a zigzag classifier. The average particle diameter at this time was 14.5 μm. Using the classified toners obtained in Examples 1 and 2 and Comparative Examples 1 and 2, a plain paper copying machine (manufactured by Konishi Roku Photo Industry Co., Ltd., U-
Bix1600) was used to test the electrophotographic toner properties. However, each toner contains hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., R-972) as a fluidity improver.
0.6% and 0.1% of zinc stearate were externally added to the above toner, respectively. The test results are shown in Table 1.

【table】

[Table] The electrophotographic properties of Examples 1 to 4 and Comparative Examples 1 to 3 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 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. (c) Gradation: Evaluated in the same way as the resolution using the 11-level gray area in the center of the test chart. (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 of the prepared developers was stirred in a copying machine, the amount of charge was measured at regular intervals, and the change in the amount of charge was measured. ○: 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 △: A lot of toner scattering The image was obtained using a fusing test device consisting of a Teflon coated roll on the upper side and a silicone rubber coated roll on the lower side, and the temperature of the upper roll can be changed at a linear speed of 70 mm/sec and a pressure between the rolls.
Fix at 0.5Kgf/cm, bend the printed part,
The following evaluation was made based on the percentage of print remaining on the folded portion. ○: Almost no peeling is observed at the folded part △: Peeling is present at the folded part ×: Peeling is present at areas other than the folded part (h) Offset resistance: Offset at each temperature is measured using the same equipment as for fixing properties. evaluated. ○: Offset did not occur ×: Offset occurred (i) Cleanability: Using a copying machine with each prepared developer, continuous copying was performed at a temperature of 30°C and humidity of 80% RH, and cleaning defects occurred. The evaluation was based on the number of copies made. (Effects of the Invention) According to the present invention, the emulsion polymerization method is used to achieve excellent resolution, image density, and gradation. It is possible to obtain an electrophotographic toner suitable for dry development that has excellent properties and offset resistance.

Claims (1)

[Claims] 1. General formula: 2-polystyryl represented by [In the formula, R ₁ represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, R ₂ represents a hydrogen atom or a methyl group, and n represents an integer of 10 to 200] Producing a main resin component by emulsion polymerizing ethyl acrylate or methacrylate and an unsaturated monomer copolymerizable with these in the presence of a colorant and/or magnetic powder, and salting out the obtained emulsion polymerization liquid. A method for producing an electrophotographic toner characterized by: 2. The method for producing an electrophotographic toner according to claim 1, wherein salting out is carried out at a temperature equal to or higher than the glass transition point of the polymer, and/or after salting out, heat treatment is performed at a temperature equal to or higher than the glass transition point.