JP2005242021A - Electrostatic latent image developing magnetic single component toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing magnetic single component toner which can keep offset resistance, improved fixing property in a low temperature region and sufficient heat resistance even when the toner is used for a high-speed image forming apparatus using a magnetic single component developing system. <P>SOLUTION: The electrostatic latent image developing magnetic single component toner comprises at least a binder resin and a release agent, wherein the release agent contains a release agent showing 65 to 85°C melting point (Wp1) and a release agent having 130 to 160°C melting point (Wp2) measured by a differential scanning calorimeter. The glass transition temperature Tg of the toner measured by a differential scanning calorimetry satisfies 70≤Wp2-Tg≤100. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic one-component toner for developing an electrostatic latent image used in an electrophotographic image forming system such as a copying machine, a facsimile machine, and a laser printer.

In order to cope with environmental problems such as energy saving resources in recent years, it is strongly required to reduce power consumption in an image forming apparatus that uses an electrostatic recording method and fixes toner onto a transfer material using a heat roller. .
As methods for reducing power consumption, low-temperature fixing, that is, a method for lowering the toner fixing temperature, a method for shortening the warm-up time, and reducing standby power are being studied.

In order to lower the fixing temperature, it has been proposed to produce toner using a low melting point wax (for example, Patent Documents 1 to 3).
However, the use of a low melting point wax is effective for improving the low-temperature fixability, but there is a problem that the heat resistance is lowered depending on the amount of the low melting point wax added and the temperature change during toner transportation.

In order to shorten the warm-up time, it is necessary to set the temperature of the heat roller higher than the set temperature of the fixing device in order to quickly raise the temperature of the fixing device in the image forming apparatus. Therefore, it is necessary to ensure sufficient offset resistance so that no offset occurs even when the temperature of the fixing device is excessively increased.
As described above, in order to achieve both low-temperature fixing and shortening of the warm-up time, while ensuring sufficient high-temperature offset property, both improve fixability in the low-temperature region, that is, more non-offset width. It is necessary to secure it widely.

Furthermore, in recent years, the speed of image forming apparatuses has been increased. However, high-speed image forming apparatuses using a one-component developing system capable of performing stable image formation over a longer period than the two-component developing system have become mainstream. It has become to.
As the speed of image forming apparatuses increases, the fixing time also decreases. In particular, the magnetic one-component toner used in the magnetic one-component jumping developing method, which is the mainstream of the one-component developing method, contains a large amount of magnetic powder. Therefore, it is more disadvantageous for fixing.
Therefore, the magnetic one-component toner used so far has a narrow non-offset width in a high-speed image forming apparatus, and it is difficult to ensure both high temperature offset property and sufficient heat resistance and low temperature fixability. there were.
Japanese Patent Laid-Open No. 7-199681 JP-A-8-297378 JP-A-8-50368

  The present invention has been made in view of the above problems, and ensures offset resistance even when used in a high-speed image forming apparatus of a magnetic one-component development system, improves fixability in a low temperature region, and further has sufficient heat resistance. It is an object of the present invention to provide a magnetic one-component toner for developing an electrostatic latent image that can secure the property. Here, the high-speed image forming apparatus of the magnetic one-component development system refers to, for example, a laser printer using a magnetic one-component jumping development system with an A4 horizontal copy speed of 50 sheets / minute or more.

  As a result of various studies on a magnetic one-component toner exhibiting excellent fixability even in an image forming apparatus of a high-speed magnetic one-component jumping development system, the present inventors have included two types of release agents having different melting points in the toner. Further, although the detailed reason is unknown, it has been found that it is effective to set the difference between the melting point of the high melting point releasing agent and the glass transition point Tg of the toner within a specific range, and the present invention is completed. It came to.

  That is, the magnetic monocomponent toner for developing an electrostatic latent image of the present invention is an electrostatic latent image developing toner comprising at least a binder resin and a release agent, and the release agent is measured by a differential scanning calorimeter. Glass transition of toner comprising a release agent having a melting point (Wp1) of 65 to 85 ° C. and a release agent having a melting point (Wp2) of 130 to 160 ° C. and measured by a differential scanning calorimeter The point Tg satisfies 70 ≦ Wp2−Tg ≦ 100.

In the present invention, the melting point measured by the differential scanning calorimeter of the release agent is a temperature showing an endothermic peak in the DSC curve of the magnetic one-component toner at the time of temperature rise measured by the differential scanning calorimeter. Further, the glass transition point Tg of the toner measured by the differential scanning calorimeter is the tangent of the curve at the start of temperature rise in the DSC curve of the magnetic one-component toner at the time of temperature rise measured by the differential scanning calorimeter. Is a temperature indicating the intersection with the tangent of the curve where the energy decreases.
FIG. 1 shows a DSC curve of the magnetic monocomponent toner of the present invention as an example. In FIG. 1, the temperature indicating the endothermic peak A and the endothermic peak B is the melting point of the release agent, and the temperature indicating the intersection of the tangent A and the tangent B is the glass transition point Tg of the toner.

  According to the present invention, two types of release agents having a specific melting point are used, and when the higher melting point and the glass transition point Tg of the toner itself satisfy the above formula, It is possible to control the balance between the reduction in heat resistance caused by the mold agent and the suppression of low-temperature fixing caused by the release agent having a high melting point, and at the time of image formation of a high-speed magnetic one-component development system. The fixing rate can be improved and a wide non-offset width can be secured. In addition, it is possible to ensure storage stability and heat resistance in the toner distribution process.

As described above, the magnetic monocomponent toner for developing an electrostatic latent image of the present invention is mainly composed of a binder resin, magnetic powder, and a release agent having two kinds of melting points. Further, in this toner, toner compounding agents such as a positive charge control agent and a release agent may be further dispersed if necessary.
Since the binder resin that can be used in the magnetic one-component toner of the present invention is usually a main factor for determining the glass transition point Tg of the toner itself, a glass transition point Tg that satisfies the above formula is used. Any known binder resin can be used without particular limitation as long as it can be obtained.

  For example, styrene resin, acrylic resin, styrene-acrylic copolymer resin, polyolefin resin such as polyethylene and polypropylene, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin, vinyl ether And thermoplastic resins such as styrene resins, N-vinyl resins, and styrene-butadiene resins. Of these, polyester resins, styrene resins, and styrene-acrylic copolymer resins are preferable.

  As the polyester resin, those obtained by polycondensation or copolycondensation of a polyhydric alcohol component and a polycarboxylic acid component can be used.

  Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1, Diols such as 5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, hydrogenated bisphenol A, polyoxyethylene Bisphenols such as bisphenol A, polyoxypropylene bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, Pentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, tri Examples of trihydric or higher alcohols such as methylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Examples of the polyvalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, Divalent carboxylic acids such as malonic acid; n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid Alkyl or alkenyl esters of divalent carboxylic acids such as isododecyl succinic acid and isododecenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2 , 5,7-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetri Rubonic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, Examples thereof include trivalent or higher carboxylic acids such as tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid. In addition, anhydrides of the above divalent or trivalent or higher carboxylic acids can also be used.

  The polyester resin can be produced by a usual method using these raw materials. For example, an alcohol component and an acid component are charged into a reaction vessel at a predetermined ratio, and the reaction is started at a temperature of 150 to 190 ° C. in the presence of a catalyst while blowing an inert gas such as nitrogen. By-product low molecular weight compounds are continuously removed from the reaction system. Thereafter, the reaction temperature is further increased to 210 to 250 ° C. to accelerate the reaction, and the target polyester resin is obtained. The reaction can be carried out under any of normal pressure, reduced pressure, and increased pressure, but after the reaction rate reaches 50 to 90%, the reaction is preferably carried out under reduced pressure of 200 mmHg or less. In addition, as a catalyst, metals, such as tin, titanium, antimony, manganese, nickel, zinc, lead, iron, magnesium, calcium, germanium, and these metal containing compounds are mentioned.

  The styrene resin and the styrene-acrylic copolymer resin are a styrene homopolymer and a copolymer with another copolymerizable monomer copolymerizable with styrene. As copolymerizable monomers, p-chlorostyrene; vinyl naphthalene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, propion Vinyl esters such as vinyl acrylate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, acrylic (Meth) acrylic acid esters such as phenyl acid, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; other acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; Vinyl ethers such as rumethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidene, etc. N-vinyl compounds of These copolymerization monomers can be used alone or in combination of two or more with a styrene monomer.

  Note that the binder resin has a desired molecular weight and glass transition point Tg by appropriately changing various conditions such as the types of monomers, the blending ratio of the monomers, the copolymerization ratio, the amount of the polymerization initiator, and the reaction time. Etc. can be synthesized.

In addition, in the binder resin, in order to improve the offset resistance or increase the toner strength, a cross-linking agent and a thermosetting resin may be used in combination with the above-described thermoplastic resin as necessary. A partially crosslinked structure may be introduced.
Such a cross-linking agent varies depending on the type of thermoplastic resin used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, bifunctional carboxylic acid esters such as ethylene glycol di (meth) acrylate, Examples thereof include vinyl compounds having 2 or 3 or more vinyl groups such as vinyl ether.

In addition, as thermosetting resins, bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, novolac type epoxy resins, polyalkylene ether type epoxy resins, cycloaliphatic type epoxy resins and the like, cyanate resins, One kind or a combination of two or more kinds can be used.
For the purpose of adjusting the molecular weight, a monocarboxylic acid or a monoalcohol may be used as necessary. Examples of the monocarboxylic acid include benzoic acid, parahydroxybenzoic acid, toluene carboxylic acid, salicylic acid, acetic acid, propionic acid, and stearic acid. Examples of the monoalcohol include monoalcohols such as benzyl alcohol, toluene-4-methanol, and cyclohexanemethanol.

  In the magnetic one-component toner of the present invention, a release agent such as a wax is dispersed and blended in the binder resin in order to improve the fixing property and the offset property. The release agent has a melting point (Wp1) measured by a differential scanning calorimeter of 65 to 85 ° C. (hereinafter sometimes referred to as “low melting point release agent”), and a melting point (Wp2) of 130 to As long as it is a release agent at 160 ° C. (hereinafter sometimes referred to as “high melting point release agent”), it can be selected from known release agents.

  In particular, the high melting point release agent satisfies the formula 70 ≦ Wp2−Tg ≦ 100 in relation to the glass transition point Tg of the toner measured by a differential scanning calorimeter depending on the type of the binder resin described above. It is necessary to choose one. By satisfying these formulas, it is possible to achieve low-temperature fixing while ensuring heat resistance and blocking resistance when using toner, and to improve the fixing rate even when used in high-speed magnetic one-component development type image forming devices. Can be made. The release agent may be a factor that affects the glass transition point Tg of the toner itself depending on the type and amount thereof, so that a glass transition point Tg satisfying the above formula can be obtained. In addition, it is necessary to select the type and amount of the release agent. In particular, the glass transition point Tg of the toner is preferably about 54 to 60 ° C. By setting the glass transition point Tg in such a range, it is possible to achieve low temperature fixing while ensuring a certain degree of storage stability and heat resistance during transportation.

  As such a release agent, conventionally known release agents can be used. For example, ester wax, alkylenebisfatty acid amide compound, natural wax (carnauba type, etc.), polypropylene wax, polyethylene wax, propylene- Examples include ethylene copolymer wax. Of these, carnauba and ester waxes are preferred as the low melting point release agent, and polypropylene waxes are preferred as the high melting point release agent. The total addition amount of the release agent is 0 with respect to 100 parts by weight of the binder resin in consideration of obtaining the release effect, ensuring the blocking resistance, and obtaining the glass transition point Tg of the toner described above. A range of 0.1 to 10 parts by weight, and a range of 3.5 to 8.0 parts by weight is preferable. The low melting point release agent is preferably, for example, 3 to 5 parts by weight with respect to 100 parts by weight of the binder resin, and the high melting point release agent is preferably, for example, about 0.5 to 3.0 parts by weight.

  Examples of the ester wax include those obtained from a reaction between a linear saturated fatty acid and an alcohol. Examples of linear saturated fatty acids include monocarboxylic acids such as myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid; dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, and dimer acid. It is done. Examples of the alcohol include linear saturated monohydric alcohols such as myristyl alcohol, cetyl alcohol, stearyl alcohol, aralkyl alcohol, behenyl alcohol, tetracosanol; ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol Linear saturated dihydric alcohols such as 1,4-butanediol; 1,2,4-butanetriol, 1,2,4-pentanetriol, 2-methyl-1,2,4-butanetriol, glycerin, 2 -Linear saturated trihydric alcohols such as methylpropanetriol, trimethylolethane, triethylolethane; linear saturated tetrahydric alcohols such as 1,2,3,6-hexanetetrol and pentaerythritol.

As the polypropylene wax, those having a number average molecular weight in the range of 1,000 to 10,000, particularly 2,000 to 6,000 are preferable.
In addition, when synthesizing a mold release agent, a mold release agent having a desired melting point is obtained by adjusting the type and amount of the raw material compound, the combination of the raw material compounds, the blending ratio, the reaction time, and the like. be able to.

In the magnetic one-component toner of the present invention, other additives may be used as long as the effects of the present invention are not impaired. Examples of such additives include charge control agents and surface treatment agents.
The toner according to the present invention is required to significantly improve the charge level and charge rising characteristics (indicator of whether to charge to a constant charge level in a short time) and to obtain characteristics such as excellent durability and stability. The positive charge control agent may be blended in an amount of 1 to 4 parts by weight per 100 parts by weight of the binder resin.

  Specific examples of such positive charge control agents include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine violet BO, Direct dyes composed of azine compounds such as N-brown 3G, azine light brown GR, azine dark green BH / C, azine deep black EW and azine deep black 3RL; nigrosine compounds such as nigrosine, nigrosine salt, nigrosine derivatives; nigrosine BK, nigrosine Examples include acid dyes composed of nigrosine compounds such as NB and nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; quaternary ammonium salts such as benzylmethylhexyldecylammonium and decyltrimethylammonium chloride. it can. These may be used alone or in combination of two or more. In particular, the nigrosine compound is optimal from the viewpoint of obtaining a quicker start-up property.

Further, a resin or oligomer having a quaternary ammonium salt, a resin or oligomer having a carboxylate, a resin or oligomer having a carboxyl group, or the like can also be used as a positively chargeable charge control agent.
More specifically, polystyrene resin having quaternary ammonium salt, acrylic resin having quaternary ammonium salt, styrene-acrylic resin having quaternary ammonium salt, polyester resin having quaternary ammonium salt, carboxylic acid Polystyrene resin with salt, acrylic resin with carboxylate, styrene-acrylic resin with carboxylate, polyester resin with carboxylate, polystyrene resin with carboxyl group, acrylic with carboxyl group 1 type, or 2 or more types, such as resin, the styrene-acrylic resin which has a carboxyl group, and the polyester-type resin which has a carboxyl group, are mentioned. In particular, a styrene-acrylic resin (styrene-acrylic copolymer) having a quaternary ammonium salt, a carboxylate or a carboxyl group as a functional group can easily adjust the charge amount to a value within a desired range. It is optimal from the point of view.

In this case, as the preferable acrylic comonomer in the styrene-acrylic resin or acrylic resin, methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, acrylic acid Examples include (meth) acrylic acid alkyl esters such as iso-butyl, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, and iso-butyl methacrylate.
In addition, examples of the quaternary ammonium salt include units derived from a dialkylaminoalkyl (meth) acrylate through a quaternization step.

  Examples of the derived dialkylaminoalkyl (meth) acrylate include di (amino) ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like ( Lower alkyl) aminoethyl (meth) acrylate; dimethylmethacrylamide, dimethylaminopropylmethacrylamide are preferred. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.

  The magnetic one-component toner of the present invention contains magnetic powder in the binder resin, and the magnetic powder is suitably blended in an amount of 50 to 100 parts by weight per 100 parts by weight of the binder resin. The toner containing the magnetic powder can be supplied to the developing area by using magnetic force alone without using a magnetic carrier or the like.

As the magnetic powder, a known powder can be used. For example, ferromagnetic iron oxides such as triiron tetroxide (Fe ₃ O ₄ ) and iron sesquioxide (γ-Fe ₂ O ₃ ), iron oxide zinc (ZnFe ₂ O ₄ ), iron yttrium oxide (Y ₃ Fe ₅ O ₁₂ ), cadmium oxide (CdFe ₂ O ₄ ), iron gadolinium oxide (Gd ₃ Fe ₅ O ₁₂ ), iron oxide copper (CuFe ₂ O ₄ ), iron oxide lead (PbFe ₁₂ O ₁₉ ), iron neodymium oxide Ferrites such as (NdFeO ₃ ), iron barium oxide (BaFe ₁₂ O ₁₉ ), iron manganese oxide (MnFe ₂ O ₄ ), iron lanthanum oxide (LaFeO ₃ ), or a composite thereof, or iron powder (Fe), Ferromagnetic metals such as cobalt powder (Co) and nickel powder (Ni) and alloys can be used alone or in combination. For example, manganese-magnesium ferrite, nickel-zinc ferrite, copper-zinc ferrite, lithium ferrite and the like can be mentioned. The particle shape of the magnetic powder is not particularly limited, and may be any shape such as a spherical shape, a cubic shape, or an indefinite shape. The average particle size of the magnetic powder is preferably from 0.1 to 1 μm, particularly preferably in a fine powder state within the range of 0.1 to 0.5 μm. Further, the magnetic powder may be used after being subjected to a surface treatment with a surface treatment agent such as a titanium coupling agent or a silane coupling agent.

  In the present invention, the magnetic one-component toner is classified into a classification method, a kneading and pulverizing method, a pulverizing and classifying or kneading and pulverizing method, a spheroidizing method by heat treatment or mechanical impact force, a melt granulating method, a spray granulating method, For example, suspension method, suspension polymerization method, emulsion polymerization method, dispersion polymerization method, interfacial polymerization method, seed polymerization method, etc.), dissolution suspension method (for example, see JP-A-11-52619), phase inversion emulsification method (For example, refer to JP-A-4-303849 and JP-A-5-66600) and the like. Among them, a method of preparing by mixing a binder resin and various compounding agents, melt-kneading using an extruder, etc., further pulverizing, and classifying to have the above-described particle size distribution, manufacturing equipment, and production The wet granulation method is preferable, and the suspension polymerization method and the emulsion polymerization method are more preferable in consideration of the properties, the circularity described above can be easily realized, and the like. Specifically, as a suspension polymerization method, a monomer solution in which a colorant and optionally an additive are dispersed is suspended in a dispersed particle size in a solvent incompatible with this solution, and the monomer is polymerized in a suspended state. Examples thereof include a method for obtaining a toner, and a method for polymerizing monomers in micelles as emulsion polymerization. The size and shape of the toner may vary depending on the heat treatment temperature or timing in the manufacturing process, the magnitude or timing of applied force (mechanical impact force, rotation speed of stirring, rotation speed, etc.), the type of raw material, etc. It can be adjusted by appropriately selecting and combining the manufacturing conditions.

  In addition, if necessary, the above toner includes colloidal silica, hydrophobic silica, alumina, titanium oxide, zinc oxide, magnesium oxide, calcium carbonate and other inorganic fine particles (usually having an average particle size of 0.3 μm or less), polymethyl Surface treatment may be performed by combining one or two or more organic fine powders such as methacrylate and fatty acid metal salts such as zinc stearate. Thereby, the fluidity and storage stability of the toner can be improved. Further, when the surface treatment is performed on fine particles such as alumina or titanium oxide, for example, when an amorphous silicon photoconductor is used, the surface of the photoconductor can be appropriately polished, and image flow can be effectively prevented. . Further, by adding the above external additives, the adhesion force of the toner to the surface of the photoconductor can be reduced, which is more preferable in terms of preventing the toner from adhering to the surface of the photoconductor.

  In the present invention, the surface treatment agent described above is used in such an amount that the original properties of the toner are not impaired, for example, the total amount of the surface treatment agent is 2.0 parts by weight or less per 100 parts by weight of the toner particles. It is good to do. The surface treatment is preferably performed by dry-mixing the toner particles and the surface treatment agent with a Henschel mixer or the like so that the fine particles of the surface treatment agent are not embedded in the toner particles.

Hereinafter, the magnetic one-component toner for developing an electrostatic latent image of the present invention will be described in detail based on examples.
As described above, the melting point measured by the differential scanning calorimeter of the release agent in this example is the endothermic peak in the DSC curve of the magnetic one-component toner at the time of temperature rise measured by the differential scanning calorimeter. It is the temperature shown. Further, the glass transition point Tg of the toner measured by the differential scanning calorimeter is the tangent of the curve at the start of temperature rise in the DSC curve of the magnetic one-component toner at the time of temperature rise measured by the differential scanning calorimeter. Is a temperature indicating the intersection with the tangent of the curve where the energy decreases. The DSC curve was measured by using a differential scanning calorimeter “DSC3210” manufactured by Mac Science Co., Ltd., heated from room temperature to 200 ° C. at a heating rate of 15 ° C./min, cooled to 25 ° C., and heated again at a heating rate of 15 The temperature was raised at a rate of ° C./min, and the amount of heat at this time was measured.

Example 1
<Synthesis of binder resin>
A monomer solution composed of 70 parts by weight of styrene and 30 parts by weight of butyl acrylate was added to 6 parts by weight of a polymerization initiator V-65 (2,2-azobis- (2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd.). The solution was added dropwise to a solution containing 200 parts by weight of toluene as a solvent (condenser was provided and toluene was refluxed) over 3 hours, and polymerization was carried out for 12 hours while maintaining the temperature at 60 ° C. Thereafter, toluene was distilled off under reduced pressure to obtain a binder resin (styrene-acrylic resin).

<Preparation of magnetic powder>
20 liters of ferrous sulfate containing Fe ²⁺ 1.5 mol / liter and 20 liters of an equal amount of 3.4N NaOH aqueous solution are mixed, and the first containing Fe (OH) ₂ at a pH of 12.5 and a temperature of 90 ° C. An aqueous iron salt solution was produced. Magnetite particles were generated by aeration of 100 liters of air per minute at a temperature of 90 ° C. for 220 minutes through a ferrous salt aqueous solution containing Fe (OH) ₂ . The produced particles were washed with water, filtered, dried, and pulverized by a conventional method to obtain octahedral magnetite particles.

<Preparation of mold release agent>
A four-neck flask reactor equipped with a Dimroth reflux apparatus and a Dean-Stark water separator was charged with 1740 parts by weight of benzene, 1300 parts by weight of a long-chain alkyl carboxylic acid component, 1300 parts by weight of a long-chain alkyl alcohol component, and 120 p-toluenesulfonic acid. Part by weight was added and dissolved with sufficient stirring. Thereafter, the mixture was refluxed for 5 hours, the valve of the water separator was opened, and azeotropic distillation was performed. After azeotropic distillation, the mixture was thoroughly washed with sodium hydrogen carbonate and dried to distill benzene. The obtained product was recrystallized, washed and purified to obtain an ester wax.

<Manufacture of toner>
Binder resin (styrene-acrylic resin) 100 parts by weight obtained as described above, magnetic powder 90.0 parts by weight, nigrosine dye (charge control agent, manufactured by Orient Chemical Industries, N-01) 5.0 parts by weight As a mold release agent, 4.0 parts by weight of an ester wax having a melting point of 73 ° C. and 1.5 parts by weight of a polypropylene wax having a melting point of 145 ° C. are added as a release agent, and these are added to a Hensial mixer 20B (Mitsui Mining Co., Ltd.). And mixed at 2500 rpm for 5 minutes.

Further, the mixture was kneaded with a twin-screw kneader (PCM-30, manufactured by Ikegai Co., Ltd.) at 200 rpm, a cylinder temperature of 120 ° C., and an input amount of 6 kg / hour. Then, it cooled at 140 mm / sec and plate | board thickness 3-4mm using the drum flake (made by Mitsui Mining Co., Ltd.).
Then, it grind | pulverized with the turbo mill (T-250 type, the turbo industry company make), and classified with the Alpine classifier.
The obtained toner was added to a Hensial mixer 20B (Mitsui Mining Co., Ltd.) together with silica so that silica (external additive, Wacker EP, H2050EP) was 0.8% by weight, and mixed at 2500 rpm for 3 minutes. Thus, the toner shown in Table 1 was produced. The obtained toner had a glass transition point Tg of 57 ° C.

Example 2
A toner was produced in the same manner as in Example 1 except that 3.0 parts by weight of ester wax having a melting point of 65 ° C. and 3.0 parts by weight of polypropylene wax having a melting point of 130 ° C. were added. The obtained toner had a glass transition point Tg of 60 ° C.

Example 3
Example 1 except that 5.0 parts by weight of commercially available carnauba wax having a melting point of 83 ° C. (TOA-201, manufactured by Toa Kasei Co., Ltd.) and 0.5 parts by weight of polypropylene wax having a melting point of 155 ° C. were added. A toner was produced in the same manner. The obtained toner had a glass transition point Tg of 55 ° C.

Comparative Examples 1-10
Each toner having a glass transition point Tg shown in Table 1 was produced using the low melting point release agent and the high melting point release agent in the ratio shown in Table 1 in the same manner as in Example 1.

  About each obtained toner, fixing property and heat resistance were measured. The results are shown in Table 2.

<Evaluation of fixability>
(Fixing rate)
As a copying machine, KM-5035 (magnetic one-component jumping development method, A4 horizontal copy speed: 50 sheets / min) manufactured by Kyocera Mita Corporation was used. The fixing temperature of this copying machine is set to 140 ° C., a solid image (manufactured by Tokyo Denshoku Co., Ltd., TC-6DS type is used, ID is adjusted to 1.3), and the obtained solid image is output. The ID was measured before and after rubbing with a weight (400 g) wound with a cover for 5 reciprocations. From the obtained results, the fixing rate (%) was determined as (ID after rubbing) / (ID before rubbing) × 100. A case where the fixing rate was 95% or more was judged “OK”, and a case where the fixing rate was less than 95% was judged “Not possible”.

(Non-offset width)
The fixing roller temperature was changed in the range of 130 to 230 ° C., and the temperature range (non-offset width) where no offset occurred was examined. The case where the temperature range “140 to 220 ° C.” falls within the range of the non-offset width is set to “possible”, and the case where the temperature range does not fall is set to “impossible”.

<Evaluation of heat resistance>
3 g of toner is placed in a sealable plastic container and heated at 58 ° C. for 3 hours. Then, it is allowed to stand at room temperature for 12 hours and applied to a 140-mesh vibrating screen using a powder destar. After sieving, the ratio of the toner remaining on the mesh was calculated, and the case where the ratio of the toner remaining on the mesh was 25% or less was “◯”, and the case where it exceeded 25% was “X”.

According to Table 2, good results were obtained with respect to the fixing rate, the non-offset width, and the heat resistance of the toners of the examples having the requirements of the present invention.
On the other hand, in the toner of the comparative example, a low temperature offset or a high temperature offset occurred, and few toners sufficiently ensure a non-offset width. Further, even in the case where the non-offset width was wide as in Comparative Example 4, the heat resistance was inferior, and none of the good results were obtained in both the fixability and the heat resistance.

  The present invention can be applied to a wide range of image forming apparatuses such as a magnetic one-component developing type laser printer, an electrostatic copying machine, a plain paper facsimile apparatus, and a composite apparatus having these functions.

2 is an example of a DSC curve of the magnetic one-component toner of the present invention.

Claims (1)

A magnetic one-component toner for electrostatic latent image development comprising at least a binder resin and a release agent, wherein the release agent has a melting point (Wp1) measured by a differential scanning calorimeter of 65 to 85 ° C. A glass transition point Tg of a toner, which includes a release agent and a release agent having a melting point (Wp2) of 130 to 160 ° C. and is measured by a differential scanning calorimeter,
70 ≦ Wp2-Tg ≦ 100
A magnetic one-component toner for developing an electrostatic latent image.

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