JPH08152746A - Electrophotographic developer - Google Patents

Abstract

PURPOSE: To enhance chargeability of toner by combining the toner containing a specified amount of a specified graft polymer as a charge controller with a magnetic carrier covered with a coat layer made of a silicone resin. CONSTITUTION: This toner contains as the charge controller the graft polymer comprising a styrene type main chain having a glass transition point of 30-60 deg.C and a number average molecular weight Mn of 2,000-100,000 and graft chains each represented by the formula in an amount of 1-10wt.% of the fixing resin. In the formula, R<1> is H atom or a 11-17C alkyl or an aryl group; each of R<2> and R<3> is H atom or a 1-17C alkyl; R<4> is a 1-12C alkyl; R<5> is H atom or a methyl group; X<-> is an anion; and n is an integer of >=2. The developer comprises a combination of this toner and the magnetic carrier covered with the coat layer made of the silicone resin or a fluorocarbon resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component electrophotographic developer containing a toner and a magnetic carrier, which is used in an image forming apparatus such as an electrostatic copying machine, a facsimile, a laser beam printer and the like. It is a thing.

[0002]

2. Description of the Related Art The toner used in the above-mentioned electrophotographic developer is usually pulverized after dispersing a colorant, a charge control agent, etc. in a suitable fixing resin. Manufactured by further classification. Of the above, various compounds such as dyes have been used as the charge control agent according to the charge polarity of the toner. Especially, as the positively charged toner, recently, environmental consideration or color toner has been used. Considering the correspondence and the like, the use of a quaternary ammonium salt which does not contain a metal and is white has been studied.

However, a usual quaternary ammonium salt having a low molecular weight has a high crystallinity and its dispersibility in a fixing resin is not sufficient, so that its chargeability is low. For this reason, low-charged toner whose charge amount is lower than a predetermined value, reverse-charged toner that is charged to the opposite polarity, or the like is likely to occur, and so-called image fog in which toner adheres to the margin portion of the formed image, or toner scattering, etc. Image defects may occur. In addition, there is a problem in the stability of charging such that the image density varies when images are repeatedly formed.

Therefore, the present inventors have proposed a conventional low molecular weight fourth
Instead of the primary ammonium salt, the following general formula (1):

[0005]

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[Wherein R ¹ is a hydrogen atom and has 11 to ¹ carbon atoms]
7 represents an alkyl group or an aryl group, and R ² and R
³ is the same or different and is a hydrogen atom or a carbon number of 1 to 1.
7 represents an alkyl group, R ⁴ represents an alkyl group having 1 to 12 carbon atoms, and R ⁵ represents a hydrogen atom, a hydroxyl group or a methyl group. X ⁻ represents an anion, and n represents an integer of 2 or more. ] The use of a polymer having a graft chain represented by the following formula as a charge control agent was investigated.

As a result, the above-mentioned graft polymer is not compatible with the fixing resin, but by adjusting the composition of the styrene polymer constituting the main chain or the physical properties such as glass transition temperature and degree of polymerization. It was found that the dispersibility in the fixing resin can be improved as compared with the low molecular weight quaternary ammonium salt. However, the toner using the above graft polymer as a charge control agent has improved chargeability as compared with a toner using a low molecular weight quaternary ammonium salt, but is still in practical use in the conventional charge control. The chargeability was insufficient as compared with that using the agent.

An object of the present invention is to provide an electrophotographic developer using a toner containing the above graft polymer as a charge control agent and having excellent chargeability of the toner.

[0009]

Means and Actions for Solving the Problems In order to solve the above problems, the present inventors have studied other constituent components of the electrophotographic developer. As a result, the magnetic carrier to be combined with the toner is coated with a coating layer made of a silicone resin or a fluorine resin instead of the usual one made of iron powder or the like. The inventors have found that the use of a so-called coating type carrier, which has an excellent effect of positively charging the toner, can improve the charge amount of the toner to a level at which it can be sufficiently put to practical use, and completed the present invention.

That is, the electrophotographic developer of the present invention is
Charge control of a graft polymer comprising a styrene-based main chain having a glass transition temperature Tg of 30 to 60 ° C. and a number average molecular weight Mn of 2000 to 10,000 and a graft chain represented by the general formula (1) The toner is contained in an amount of 1 to 10 parts by weight with respect to 100 parts by weight of the fixing resin, and a magnetic carrier whose surface is coated with a coating layer made of a silicone-based resin or a fluorine-based resin. It is what

The present invention will be described below. In the present invention, the toner is configured in the same manner as the conventional one except that the above graft polymer is used as the charge control agent. That is, the toner is formed by mixing the charge control agent and the colorant in the fixing resin.

The fixing resin of the above is not limited to this, but is, for example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer. Polymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-
Ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer,
Styrene-phenyl acrylate copolymer etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-methacryl) Acid phenyl copolymer, etc.), styrene-
Styrene resins such as α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer (homopolymer or copolymer containing styrene or styrene substitution product), polyvinyl chloride, low molecular weight polyethylene, Low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl butyral, ethylene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, ionomer resin, polyurethane resin, silicone resin, ketone resin , Xylene resin, polyamide resin and the like, and these may be used alone or in combination of two or more kinds.

Of these, styrene-acrylic resins such as styrene-acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers, which are widely used as fixing resins for electrophotographic toners, are particularly preferable. As the colorant to be blended in the fixing resin, various conventionally known dyes, pigments and the like can be used, but in the case of a black toner, carbon black is mainly used.

As the carbon black, various conventionally known carbon blacks such as channel black, roller black, disc black, gas furnace black, oil furnace black, thermal black and acetylene black can be used. The amount of carbon black blended is not particularly limited in the present invention, but since the carbon black itself has conductivity, it also plays a role as a means for controlling the electrical characteristics relating to the charging of the electrophotographic toner. Therefore, it is preferable to set the preferable range of the blending amount according to the intended toner performance. Although not limited to this, the blending amount of carbon black may be 1% for the fixing resin 1.
It is preferably about 1 to 15 parts by weight with respect to 00 parts by weight in view of the charging property of the electrophotographic toner.

As the charge control agent, the glass transition temperature Tg is 30 to 60 ° C. and the number average molecular weight Mn is as described above.
A graft polymer comprising a styrene-based main chain having a ratio of 2000 to 10,000 and a graft chain represented by the general formula (1) is used. The styrene-based polymer constituting the main chain in such a graft polymer is not particularly limited, but a styrene-based polymer having a proportion of styrene in the constituent monomers of 50 mol% or more is preferably used. . The graft polymer using a main chain having a styrene ratio of less than 50 mol% is a fixing resin, although it depends on the glass transition temperature Tg of the main chain, the value of the number average molecular weight Mn, or the type of fixing resin. There is a risk that the dispersibility in the solution will be insufficient. Examples of other monomers that form a styrene-based main chain together with styrene include, for example, styrene derivatives, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, and mono monomers. Examples thereof include olefin-based monomers, halogenated olefin-based monomers and polyvinyl-based monomers.

Of these, examples of styrene derivatives include α-methylstyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene,
Examples thereof include p-chlorostyrene, p-ethylstyrene, sodium styrenesulfonate and the like. Examples of acrylic monomers include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and acrylic acid-2-
Ethylhexyl, cyclohexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid-
2-ethylhexyl, cyclohexyl methacrylate, phenyl methacrylate, β-hydroxyethyl methacrylate, propyl γ-aminoacrylate, propyl γ-N, N-diethylaminoacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate Examples include esters.

Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate and the like. Examples of vinyl ether-based monomers include vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclobexyl ether and the like.

Examples of the diolefin-based monomer include butadiene, isoprene, chloroprene and the like. Examples of the monoolefin-based monomer include ethylene, propylene, butene-1, pentene-1, 4-methylpentene-1 and the like. Examples of the halogenated olefin-based monomer include vinyl chloride and encavinylidene.

Further, examples of the polyvinyl-based monomer include divinylbenzene, diallyl phthalate, tricyanurate and the like. Glass transition temperature T of the main chain
The reason why g and the number average molecular weight Mn are limited within the above range is as follows. That is, when the glass transition temperature Tg of the main chain is less than the above range, or the number average molecular weight Mn is less than the above range, the heat resistance of the toner is lowered and the toner is offset or blocked, or the toner is not transferred to the photosensitive drum. This causes problems such as fusion. On the other hand, when the glass transition temperature Tg of the main chain exceeds the above range or the number average molecular weight Mn exceeds the above range, the dispersibility of the graft polymer in the fixing resin decreases, and as a result, the toner itself The chargeability is lowered, and even if it is combined with the above-mentioned coating type carrier, the chargeability at a practical level cannot be obtained.

In the graft chain represented by the general formula (1), which is graft-bonded to the main chain, examples of the alkyl group having 11 to 17 carbon atoms corresponding to the group R ¹ include undecyl, dodecyl, tridecyl, Examples thereof include linear or branched alkyl groups such as tetradecyl, pentadecyl, hexadecyl and heptadecyl. Examples of the aryl group include phenyl, biphenyl, naphthyl, anthryl, phenanthryl, o-terphenyl and the like.

1 to 1 carbon atoms corresponding to the radicals R ² and R ³
Among the 7 alkyl groups, examples of the alkyl group having 11 to 17 carbon atoms include the same groups as described above. Also, carbon number 1
Examples of the alkyl group of 10 include linear groups such as methyl, ethyl, normal propyl, isopropyl, normal butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl. Alternatively, a branched alkyl group can be used.

Examples of the alkyl group having 1 to 12 carbon atoms corresponding to the group R ⁴ include methyl to dodecyl groups. Examples of the anion corresponding to X ⁻ include halogen ions such as chlorine ion, bromine ion, fluorine ion, and iodine ion, as well as formula (2):

[0023]

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Sulfonate ions such as hydroxynaphthosulfonate ion, p-toluenesulfonate ion, methylsulfonate ion and the like, sulfate ion, nitrate ion, phosphate ion, borate ion, oxoate ion, and carboxylate ion represented by And so on. The degree of polymerization corresponding to n is limited to 2 or more. When n is 1, the effect of imparting chargeability to the toner is low although it depends on the number of grafts to the main chain. Therefore, a toner using such a graft polymer can be used in combination with a coating type carrier. Practical level chargeability cannot be obtained.

The upper limit of the degree of polymerization n is not particularly limited as long as it is 2 or more, but if the degree of polymerization is too high,
Since the dispersibility of the graft polymer in the fixing resin may be lowered and the effect of imparting the charging property to the toner may be lowered, the range of about 2 to 100 is particularly preferable within the above range. To synthesize the above graft polymer, chlorine is added to a styrene-based polymer corresponding to the main chain.
Introduce a functional group such as bromine. To introduce the functional group into the styrene-based polymer, a monomer having the functional group,
Generally, it is copolymerized with styrene or the like, but a functional group may be introduced later into the polymer after polymerization.

Next, the above polymer and the general formula (3):

[0027]

[Chemical 4]

[In the formula, R ¹ , R ² and R ³ represent the same groups as described above. ] And an imidazole derivative represented by the general formula (4):

[0029]

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[In the formula, Y represents a halogen atom such as chlorine or bromine. R ⁴ and R ⁵ represent the same groups as described above. ] It may be made to react with the dihalide represented by] at an appropriate molar ratio. The reaction is carried out in a solvent inert to the imidazole derivative and the dihalide. Examples of the solvent include aromatic solvents such as benzene, toluene and xylene, ketone solvents such as acetone and methyl ethyl ketone, aprotic polar solvents such as dimethylformamide, dimethylacetamide and dimethyl sulfoxide,
Alternatively, a mixed solvent of these solvents with an alcohol-based solvent such as methanol, ethanol, isopropanol, etc., or water may be used.

If necessary, a monohalide or N-substituted imidazole may be added to the above reaction system in order to block the end of the graft group. In addition, an alkali such as sodium hydroxide, potassium hydroxide or sodium carbonate may be added to the reaction system in order to neutralize hydrogen halide generated by the reaction.

As the reaction procedure, dihalide is added dropwise to a solution prepared by previously dissolving the polymer, the imidazole derivative and, if necessary, an alkali, and the above components are simultaneously dissolved in the solution. It is conceivable that a polymer is added to a reaction product of an imidazole derivative and a dihalide, and the like.

The monohalide and N-substituted imidazole for end-capping are preferably not added to the reaction system from the start of the reaction but added at a stage where the reaction has progressed to some extent. The reaction is carried out at 30 to 200 ° C., preferably 60 to 180.
It may be performed at a temperature of C for about 2 to 20 hours. In the reaction product obtained by the above reaction, the anion corresponding to X ⁻ in the general formula (1) is halogen. Therefore, in order to replace this with an anion other than halogen, the reaction product is It may be added to the aqueous solution of the salt (alkali metal salt, ammonium salt, etc.) and stirred.

After completion of the reaction, extraction of unreacted components with water,
Alternatively, reprecipitation with water and further removal of the homopolymer of the graft chain give a graft polymer. The blending amount of the above graft polymer as a charge control agent is limited to 1 to 10 parts by weight with respect to 100 parts by weight of the fixing resin. If the blending amount of the graft polymer is less than the above range, the chargeability of the toner itself will be deteriorated, and a practical level of chargeability will not be obtained even when combined with a coating type carrier. On the contrary, when the blending amount of the graft polymer exceeds the above range, the heat resistance of the toner is lowered, and problems such as offset, blocking, and fusion to the photosensitive drum occur.

In addition to the above colorants and charge control agents, various additives such as a release agent (offset preventing agent) may be added to the toner. Examples of the release agent (anti-offset agent) include aliphatic hydrocarbons, aliphatic metal salts, higher fatty acids, fatty acid esters or partially saponified products thereof, silicone oil, and various waxes.
Of these, aliphatic hydrocarbons having a weight average molecular weight of about 1,000 to 10,000 are preferable. Specifically, one or a combination of two or more of low molecular weight polypropylene, low molecular weight polyethylene, paraffin wax, a low molecular weight olefin polymer composed of olefin units having 4 or more carbon atoms is suitable.

The release agent is 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the fixing resin,
Be compounded. In addition, various additives such as a stabilizer may be added in an appropriate amount. Toner is a mixture obtained by uniformly premixing the above components with a dry blender, a Henschel mixer, a ball mill, etc., and uniformly using a kneading device such as a Banbury mixer, roll, uniaxial or biaxial extrusion kneader. After melt-kneading, the obtained kneaded product is cooled, pulverized, and if necessary, classified, or may be manufactured by a suspension polymerization method or the like.

The particle size of the toner is 3 to 30 μm, especially 4 to
It is preferably 20 μm, and in the case of a toner having a small particle diameter for the purpose of improving the quality of a formed image, it is preferably about 4 to 10 μm. As the magnetic carrier to be combined with the above-mentioned toner, a coating type carrier whose surface is coated with a coating layer made of a silicone resin or a fluorine resin as described above is used.

As the magnetic particles serving as the base of the coating type carrier, various known structures can be used. Examples of such magnetic particles include particles of iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, cobalt and the like, and particles of alloys of these materials with manganese, zinc, aluminum and the like, Iron-nickel alloy, particles of iron-cobalt alloy, particles obtained by dispersing fine powders of the various materials in a binder resin, titanium oxide,
Ceramic particles such as aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, lead titanate, lead zirconate, and lithium niobate, phosphoric acid Ammonium dihydrogen (NH ₄ H ₂ P
O ₄ ), potassium dihydrogen phosphate (KH ₂ PO ₄ ), particles of a high dielectric constant substance such as Rochelle salt, and the like can be mentioned.

Among them, iron powder such as iron oxide and reduced iron, or ferrite particles are preferable. These particles have a small rate of change in electric resistance due to changes in the environment and aging, and since the magnetic brush has soft ears, an image with good image quality can be formed and the cost is low. The ferrite particles include zinc-based ferrite, nickel-based ferrite, copper-based ferrite, nickel-zinc-based ferrite, manganese-magnesium-based ferrite, copper-magnesium-based ferrite, manganese-zinc-based ferrite, manganese-copper-zinc-based ferrite, and the like. Particles are included.

The magnetic particles are formed to have a particle size of 10 to 200 μm, preferably 30 to 150 μm. The saturation magnetization of the magnetic particles is not limited to this, but is 35 to 70e.
It is preferably about mu / g. As the silicone-based resin that is the material of the coat layer that coats the surface of the magnetic particles, various thermosetting silicone resins can be used, but in particular, a methyl silicone-based resin, more specifically, C
A methyl-dimethyl silicone resin containing H ₃ SiO _3/2 and (CH ₃ ) SiO as main structural units is preferably used. Specific examples of such a methyl-dimethyl silicone resin include product number SR240 manufactured by Toray Dow Corning Co.
0, SR2410, SR2411, or product numbers KR251 and KR255 manufactured by Shin-Etsu Chemical Co., Ltd.

The coating layer made of a silicone resin is applied to the surface of the magnetic carrier with a coating agent prepared by dissolving the silicone resin in an appropriate solvent, and then heated to remove the solvent and cure the resin. It is formed by If hydroxyl groups and the like remain in the coat layer, the negative charging property of the toner itself may decrease, and the effect of positively charging the toner may become insufficient, so the heating temperature during curing is set higher than usual. Then, it is desirable to remove hydroxyl groups and the like as much as possible.

On the other hand, as a coating layer made of a fluorine-based resin for coating the surface of the magnetic particles, fine particles of a fluorine-based resin such as an ethylene tetrafluoride resin in a binder resin such as a polyamide-imide resin or an epoxy resin. Those dispersed are preferably used. Among such fluorine-based resins, in the case of using the polyamide-imide resin as the binder resin, the content of the polyamide-imide resin is preferably 10 to 40% by weight. Specific examples include Teflon S958-207 and Teflon S958P-, trade names manufactured by DuPont.
10255 etc. are mentioned.

When the epoxy resin is used as the binder resin, the content of the epoxy resin is 10%.
It is preferably about 40% by weight. As a specific example,
Examples include Teflon S954-100 and Teflon S954-101 manufactured by DuPont. The coating layer made of a fluororesin is a coating agent prepared by dissolving the fluororesin in an appropriate solvent, which is applied to the surface of the magnetic carrier and then heated to remove the solvent, and a polyamide-imide resin which is a binder resin. It is formed by curing reaction of epoxy resin.

The coating agent can be applied by a mechanical mixing method in which the magnetic particles and the coating agent are uniformly mixed using a mixer such as a V-type blender or a Nauter mixer. The coating agent is sprayed onto the magnetic particles. Spraying method, dipping method in which magnetic particles are immersed in a coating agent, magnetic particles are put in a fluidized bed coating device, and air is supplied from the bottom of the coating device to suspend the magnetic particles to make them in a fluidized state and A so-called fluidized bed method, in which a coating agent is sprayed onto fluidized magnetic particles from above the coating device, a rolling bed method in which magnetic particles in a rolling state are brought into contact with a coating agent, and the like can be used.

The thickness of the coat layer is 0.05 to 1 μm, preferably 0.1 to 0.7 μm. If necessary, the coat layer may contain additives such as silica, alumina, carbon black and aliphatic metal salts for adjusting the properties of the coat layer.

An external additive may be externally added to the electrophotographic developer of the present invention comprising the above toner and a magnetic carrier for the purpose of improving fluidity. As the external additive, various conventionally known external additives such as inorganic fine particles and fluororesin particles can be used. Particularly, a silica-based surface treatment agent containing hydrophobic or hydrophilic silica fine particles, for example, ultrafine particles. Anhydrous silica and colloidal silica are preferably used.

The amount of the external additive to be added is not particularly limited and may be the same as the conventional amount. Specifically, it is preferable to externally add about 0.1 to 3.0 parts by weight of the external additive to 100 parts by weight of the toner, but the external addition amount of the external additive may fall within this range in some cases. You may come off. The toner concentration of the electrophotographic developer of the present invention is the same as the conventional toner concentration, that is, 2 to 15% by weight.
The degree is preferred.

[0048]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. <Synthesis 1 of Graft Polymer> A styrene-based polymer having a functional group (styrene content 90 mol%, glass transition temperature T
g = 40 ° C., number average molecular weight Mn = 6000) 100 parts by weight, and the group R ¹ in the general formula (2) is an undecyl group, R ²
90 parts by weight of an imidazole derivative in which is a hydrogen atom and R ³ is a methyl group, and a dihalide 50 in which the group R ⁴ in the general formula (3) is a methyl group, R ⁵ is a hydrogen atom, and Y is a chlorine atom. And 20 parts by weight of sodium carbonate in dimethylformamide.

Then, the mixture was stirred under reflux at 80 ° C. for 4 hours for reaction, 4 parts by weight of benzyl chloride as a monohalide for capping the end was added to the reaction system, and the mixture was further stirred at 80 ° C. for 2 hours. To react. Next, 2000
While stirring 200 parts by weight of sodium hydroxynaphthosulfonate in 200 parts by weight of water with a homomixer, the reaction product obtained by the above reaction was added to obtain a precipitate, which was washed with water, filtered, It was dried to obtain a graft polymer I. <Synthesis 2 of Graft Polymer> As a styrene-based polymer having a functional group, 100 parts by weight of a styrene-containing polymer having a styrene content of 90 mol%, a glass transition temperature Tg of 30 ° C. and a number average molecular weight of Mn of 2000 are used. In the same manner as in Synthesis 1 of Graft Polymer, Graft Polymer II was synthesized. <Synthesis 3 of Graft Polymer> As a styrene-based polymer having a functional group, 100 parts by weight of a styrene-containing polymer having a styrene content of 90 mol%, a glass transition temperature Tg = 60 ° C. and a number average molecular weight Mn = 10000 are used. In the same manner as in Synthesis 1 of Graft Polymer, Graft Polymer III was synthesized. <Synthesis 4 of Graft Polymer> As a styrene-based polymer having a functional group, 100 parts by weight of a styrene-containing polymer having a styrene content of 90 mol%, a glass transition temperature Tg of 10 ° C. and a number average molecular weight of Mn of 1000 are used. A graft polymer IV was synthesized in the same manner as in Synthesis 1 of graft polymer. <Synthesis 5 of Graft Polymer> As a styrene-based polymer having a functional group, 100 parts by weight of a styrene-containing polymer having a styrene content of 90 mol%, a glass transition temperature Tg of 70 ° C. and a number average molecular weight of Mn of 12000 are used. A graft polymer V was synthesized in the same manner as in Synthesis 1 of graft polymer. Example 1 <Manufacture of Toner> 100 parts by weight of a styrene-acrylic resin as a fixing resin, 8 parts by weight of carbon black as a colorant, and a charge control agent of Synthesis 1 of the above graft polymer were used. 4 parts by weight of the graft polymer I and 3 parts by weight of polypropylene wax as a release agent are mixed, melt-kneaded, pulverized and classified to have a particle size of 5 to 20 μm.
A positive charging toner was manufactured.

100 parts by weight of this toner is used as an external additive for hydrophobic silica (product number RP manufactured by Nippon Aerosil Co., Ltd.
130) 0.2 parts by weight of surface treatment. <Production of magnetic carrier> A coating agent in which a silicone resin (product number SR2400 manufactured by Toray Dow Corning Co., Ltd.) is dissolved in toluene is applied to the surface of ferrite particles having a particle diameter of 80 μm, which are magnetic particles, by a fluidized bed method. Three
A heat treatment was carried out at 00 ° C. for 1 hour to produce a magnetic carrier in which the surface of the magnetic particles was coated with a coating layer made of 1.0 wt% of a silicone resin. <Production of Electrophotographic Developer> The toner and the magnetic carrier were mixed so as to have a toner concentration of 3% by weight to produce an electrophotographic developer of Example 1. Comparative Example 1 A toner was prepared in the same manner as in Example 1 except that the content of the charge control agent, Graft Polymer I, in the toner was 0.5 part by weight. An electrophotographic developer of Comparative Example 1 was manufactured by mixing the same magnetic carrier as described above in the same ratio. Comparative Example 2 A toner was prepared in the same manner as in Example 1 except that the content of the charge control agent, Graft Polymer I, in the toner was 12 parts by weight. An electrophotographic developer of Comparative Example 2 was manufactured by mixing the same magnetic carrier as above in the same ratio. Comparative Example 3 A toner was prepared in the same manner as in Example 1 except that 2 parts by weight of nigrosine dye was used as the charge control agent, and this was mixed with the same magnetic carrier as that prepared in Example 1 in the same ratio. Thus, the electrophotographic developer of Comparative Example 3 was manufactured. Comparative Example 4 A toner was prepared in the same manner as in Example 1 except that 2 parts by weight of a low molecular weight quaternary ammonium salt was used as a charge control agent, and the same magnetic carrier as that prepared in Example 1 was used. The electrophotographic developer of Comparative Example 4 was manufactured by mixing in the same ratio.

The following tests were carried out on the electrophotographic developers of the above Examples and Comparative Examples to evaluate their characteristics. Dispersibility Evaluation Of the electrophotographic developers of Examples and Comparative Examples, the dispersibility of the charge control agent in the toner was evaluated by a transmission electron microscope (TEM).

Examples using a graft polymer or a low molecular weight quaternary ammonium salt as the charge control agent,
In Comparative Example, TEM observation was performed after dyeing with RuO ₄ , and in Comparative Example 3 using a nigrosine dye, TEM observation was performed as it was. Then, the dispersion state in which the charge control agent did not aggregate and was dispersed almost uniformly was evaluated as good dispersibility (= ○), and the dispersion state in which there were lumps due to the aggregation of the charge control agent was evaluated as poor dispersibility (= ×). . Heat resistance test 20 g of toner among the electrophotographic developers of Examples and Comparative Examples
In a cylindrical cylinder made of glass (inner diameter 26.5 mm), put a weight of 100 g on the toner, leave it for 30 minutes at a predetermined temperature, remove the cylinder, observe the toner, and collapse the toner. Disappearing temperature (B ₁ , ℃)
Was recorded. Fixability Test The electrophotographic developers of Examples and Comparative Examples were remodeled so that the fixing temperature of the heating fixing roller (peripheral speed 150 mm / sec) could be adjusted. Electronic facsimile machine (Model number AF manufactured by Mita Industry Co., Ltd.)
-1000), a solid black image was drawn while changing the fixing temperature.

Next, the image density of the picture image fixed on the paper surface by the heat fixing roller was measured by a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.), and the surface thereof was 26 mm in height. The surface of a cylinder made of mild steel having a diameter of 50 mm was forcibly rubbed 5 times with a weight (20 g / cm ² ) in which a cotton cloth was coated on the bottom surface. Then, the image density after rubbing is measured again by the reflection densitometer, and the fixing rate (%) is obtained by the following formula, and the minimum fixing temperature (F ₁ , ° C) at which the fixing rate becomes 95% or more is determined. Recorded.

Fixing rate (%) = (image density after rubbing) /
(Image density before rubbing) × 100 Offset resistance test The electrophotographic developers of Examples and Comparative Examples were used in the same electrostatic facsimile machine as in the above-mentioned fixing property test, and while changing the fixing temperature, black was obtained. A solid image was printed and the highest fixing temperature (F ₂ , ° C) at which offset did not occur was recorded. Actual Machine Test The electrophotographic developers of Examples and Comparative Examples were used in the same electrostatic facsimile machine as in the above fixing test, but the fixing temperature was fixed at 150 ° C., and 30,000 sheets of continuous images were formed. . Then, at the stage of forming the images of the 1st, 5000th, 10000th, 20000th, and 30000th sheets, the formed image and the inside of the apparatus are visually observed to determine whether there is an image defect and whether the apparatus is defective. The presence / absence of toner abnormality inside was recorded. Then, when there is neither image defect nor toner abnormality, O is marked in the table, and when image defect or toner abnormality is observed, X is marked in the table, and details of the defect or abnormality are recorded in the margin. . In addition, although an image defect or a toner abnormality was slightly observed, when there is no problem in practical use, Δ is marked.

The above results are shown in Table 1.

[0056]

[Table 1]

* 1: Toner scattering and image fogging occur due to insufficient charge amount. * 2: Toner blocking occurs in the device. * 3: Image density decreases due to overcharge. Example 2 A toner was prepared in the same manner as in Example 1 except that 4 parts by weight of the graft polymer II prepared in Synthesis 2 of the graft polymer was used as the charge control agent, and the toner was prepared in Example 1. An electrophotographic developer of Example 2 was manufactured by mixing the same magnetic carrier as that of No. 1 in the same ratio. Example 3 A toner was prepared in the same manner as in Example 1 except that 4 parts by weight of the graft polymer III produced in Synthesis 3 of the above graft polymer was used as the charge control agent.
Mixed with the same magnetic carrier that was manufactured in the same ratio,
The developer for electrophotography of Example 3 was manufactured. Comparative Example 5 A toner was prepared in the same manner as in Example 1 except that 4 parts by weight of the graft polymer IV prepared in Synthesis 4 of the graft polymer was used as the charge control agent, and the toner was prepared in Example 1. An electrophotographic developer of Comparative Example 5 was produced by mixing the same magnetic carrier as in No. 1 in the same ratio. Comparative Example 6 A toner was prepared in the same manner as in Example 1 except that 4 parts by weight of the graft polymer V prepared in Synthesis 5 of the graft polymer was used as the charge control agent, and the toner was prepared in Example 1. An electrophotographic developer of Comparative Example 6 was manufactured by mixing the same magnetic carrier as in No. 1 in the same ratio.

With respect to the electrophotographic developers of the above Examples and Comparative Examples, the above-mentioned respective tests were conducted and the characteristics thereof were evaluated. The results are shown in Table 2 together with the results of Example 1.

[0059]

[Table 2]

* 4: Toner is fused to the photosensitive drum. * 5: Toner scattering and image fogging due to insufficient charge amount. Example 4 The electrophotographic developer of Example 4 was manufactured by mixing the same toner as that manufactured in Example 1 with the following magnetic carrier in the same ratio. <Production of magnetic carrier> A coating agent prepared by dissolving a fluorocarbon resin (Teflon S954-100, manufactured by DuPont) in tetrahydrofuran is applied to the surface of ferrite particles having a particle diameter of 80 μm, which are magnetic particles, by a fluidized bed method. Then, heat treatment was carried out at 200 ° C. for 0.5 hour to produce a magnetic carrier in which the surface of the magnetic particles was covered with a coating layer made of a fluorine-based resin of 0.5% by weight. Comparative Example 7 The electrophotographic developer of Comparative Example 7 was prepared by mixing the same toner as that prepared in Example 1 with an iron powder carrier (particle size: 80 μm) whose surface was not coated with a coating layer in the same ratio. did.

With respect to the electrophotographic developers of the above Examples and Comparative Examples, the actual machine test and the following charge rising property test were conducted to evaluate the characteristics. Charge Rising Characteristics Test Each of the electrophotographic developers of Examples and Comparative Examples was placed in a plurality of polypropylene containers (poly container, content volume 3 ml), and allowed to stand in a working environment for 1 day for humidity control.

Next, in each of the examples, one plastic container was placed in a mini bottle (internal volume: 300 ml), and the mini bottle was rotated at 100 rpm. p. m. I rotated it. Then, after rotating the mini bottle 10 times, the charge amount (μC / μC /
g) was measured. The above test is performed by rotating the mini bottle 50 times, 100 times, 500 times, 1000 times or 30 times.
It was set to 00 times and repeated, and the rising electrification characteristics of the electrophotographic developers of Examples and Comparative Examples were evaluated from the transition of the electrification amount with the rotation number of the mini bottle.

The results are shown in Table 3 together with the results of Example 1.

[0064]

[Table 3]

* 6: Toner scattering and image fogging occur due to insufficient charge amount.

[0066]

As described above in detail, the electrophotographic developer of the present invention is a toner in which a polymer in which a graft chain of a specific structure is bonded to the main chain of a styrene polymer is used as a charge control agent, Since the surface of the toner is coated with a coating layer made of a silicone-based resin or a fluorine-based resin, which is combined with a magnetic carrier having an excellent charging property, the charging property of the toner can be improved.

Front page continuation (72) Inventor Keitaro Toyota 1-2-2 Tamatsukuri Chuo-ku, Osaka City, Osaka Prefecture Mita Industry Co., Ltd.

Claims (1)

[Claims] 1. A styrene-based main chain having a glass transition temperature Tg of 30 to 60 ° C. and a number average molecular weight Mn of 2000 to 10,000, and a compound represented by the general formula (1): [In the formula, R ¹ represents a hydrogen atom, an alkyl group or an aryl group having 11 to 17 carbon atoms, R ² and R ³ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 17 carbon atoms, R 2 ⁴ represents an alkyl group having 1 to 12 carbon atoms,
R ⁵ represents a hydrogen atom, a hydroxyl group or a methyl group. X ⁻ represents an anion, and n represents an integer of 2 or more. ] A toner containing a graft polymer composed of a graft chain represented by the following as a charge control agent in a range of 1 to 10 parts by weight with respect to 100 parts by weight of a fixing resin, and a silicone resin or a fluorine resin. An electrophotographic developer comprising a combination of a magnetic carrier having a surface coated with a coating layer.