JPH083668B2 - Electrostatic latent image developer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrostatic latent image developer used when a negatively charged electrostatic latent image is visualized with positively charged toner particles. More specifically, the present invention relates to an electrostatic latent image developer used for developing a negatively charged electrostatic latent image, wherein positively chargeable toner particles and a positive charge are imparted to the toner particles. The present invention relates to a two-component system electrostatic latent image developer containing a positive charge imparting carrier.

[Prior Art and its Problems] A two-component electrostatic latent image developer used in an electrophotographic method to visualize a negatively charged electrostatic latent image positively charges positively chargeable toner particles and this toner. And a carrier capable of being added (positive charge imparting carrier).

The invention of a two-component electrostatic latent image developer (toner) containing toner particles having a polyester resin as a binder and a single-layer carrier having a vinylidene fluoride / tetrafluoroethylene copolymer as a coating agent has already been disclosed. (Japanese Patent Laid-Open No. 60-1
(See Japanese Patent Publication No. 76049).

However, according to the study by the present inventor, the electrostatic latent image developer according to the present invention is used for a long period of time and under severer conditions (for example, temperature 30 ° C., humidity 80%) than normal use conditions. It has been found that good properties tend to be deteriorated in the case of doing so.

This is because the adhesion between the vinyldenfluoride / tetrafluoroethylene copolymer and the carrier core material is not always good, and therefore, due to repeated use or use under severe conditions, It is considered that the main cause is that the vinylden fluoride / tetrafluoroethylene copolymer peels off and the characteristics of the carrier such as positive charge imparting property change.

Generally, a method of increasing the thickness of the coating layer is conceivable as a method of preventing the characteristic change due to desorption of the resin component coating the carrier core material.

However, since the fluoropolymer has poor adhesion to the core material and poor film-forming property, pinholes are likely to occur, and even if this method is used, it is difficult to effectively prevent deterioration of carrier characteristics. In addition, since this fluoropolymer has a scale-like resin layered around the core material, the scale-like resin may be peeled off by repeated use of the electrostatic latent image developer, so that the mechanical strength of the fluoropolymer is sufficiently compensated. I can't. further,
When the thickness of the coating layer is increased, there are problems that the solvent used when forming the coating layer remains in the coating layer, the fluidity of the electrostatic latent image developer decreases, and the rise of the charge amount is poor.

On the other hand, in order to eliminate the drawbacks of the single-layer coated carrier, the use of a multi-layer coated carrier formed by forming a plurality of coating layers around the carrier core material has been studied.

As such a multi-layer coated carrier, JP-A-61-110
In JP 160, a triboelectric charge control layer and a peelable surface layer are sequentially laminated on a core material, and the peelable surface layer contains a polymer of a fluorinated alkyl acrylate or a fluoroalkyl methacrylate, Disclosed is an invention whose main feature is that the monomer is 50% by weight or less of the material of the surface layer and can be charged according to the characteristics of the friction control layer.

That is, the multi-layer coated carrier, by the content of the fluorinated alkyl (meth) acrylate monomer in the peelable surface layer (outermost layer) is 50 wt% or less,
It became possible to change the charge imparting property of the carrier by making the characteristics of the resin of the friction control layer (intermediate layer) manifest, regardless of the characteristics of the resin of the peelable surface layer (outermost layer). Therefore, the charge imparting property to the toner particles in the carrier is always determined by the resin used in the friction control layer (intermediate layer).

However, when a positive charge imparting resin (positive charge imparting property) is used as the resin of the friction control layer (intermediate layer), the charge imparting property of the resin of the friction control layer (intermediate layer) becomes apparent with time. Therefore, the charge amount of the electrostatic latent image developer at the initial stage of use may be significantly different from the charge amount of the electrostatic latent image developer after repeated use. Moreover, there is a problem in that the chargeability of the carrier surface becomes unstable under the conditions of high temperature and high humidity both at the initial stage of use and at the time of repeated use, resulting in deterioration of development quality.

Therefore, in the carrier described in the above publication, the charge imparting property varies depending on the type of the resin of the friction control layer (intermediate layer), and thus a toner using a resin having a strong negative charging property such as a polyester resin as a binder. Not suitable as a carrier for use with particles.

[Object of the Invention] The present invention is an electrostatic latent image developer containing toner particles and a multilayer coat carrier capable of strongly imparting positive charging properties to the toner particles. It is an object of the present invention to provide an electrostatic latent image developer which is good and whose performance is maintained for a very long period of time.

In particular, an object of the present invention is to provide an electrostatic latent image developer used in electrophotography and the like, which always has stable characteristics even under high temperature and high humidity conditions.

[Means for Achieving the Object] The constitution of the present invention for achieving the object is a toner particle used for visualizing a negatively charged electrostatic latent image with positively charged toner particles, and What is claimed is: 1. An electrostatic latent image developer comprising a carrier for imparting a positive charge to toner particles, the carrier comprising a core material, an intermediate layer comprising a styrene resin, and a fluorinated alkyl (meth) acrylate polymer. The charge control layer is coated in this order, and the triboelectric charge control layer contains more than 50% by weight of a fluorinated alkyl (meth) acrylate repeating unit,
The toner particles include a polyester resin, which is an electrostatic latent image developer.

The electrostatic latent image developer of the present invention is an electrostatic latent image developer that visualizes an electrostatic latent image formed by being negatively charged in an apparatus such as an electrophotographic apparatus with positively charged toner particles. . Therefore, it cannot be used to develop a positively charged electrostatic latent image.

As the core material of the carrier of the electrostatic latent image developer of the present invention,
Inorganic powder such as glass beads, metal powder such as aluminum powder, iron powder and nickel powder, metal oxide powder such as iron oxide, ferrite and magnetite, organic metal powder such as carbonium iron powder, etc. The material used as can be used.

The core material usually has a particle diameter such that carrier particles obtained by coating the intermediate coating layer and the triboelectrification control layer on the core material have a particle diameter within the range of 10 to 500 μm. The shape of the particles of the core material is not particularly limited as long as it is a commonly used shape, and a spherical or elliptical shape is preferable in consideration of the powder characteristics of the obtained carrier.

Examples of the styrene-based resin forming the intermediate layer of the carrier include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene. Halogenated styrenes such as alkyl styrene, fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene, etc., and homopolymers of styrene monomers such as nitrostyrene, acetylstyrene and methoxystyrene, or of these styrene monomers. Examples thereof include copolymers and copolymers of these styrene monomers and alkyl (meth) acrylates.

The styrene resin is preferably a homopolymer of styrene or a copolymer of styrene and alkyl (meth) acrylate, and particularly, styrene and alkyl (meth).
Copolymers with acrylates are preferred.

The styrene resin has good adhesion to the core material and the fluoroalkyl (meth) acrylate polymer. Therefore, the styrene-based resin not only improves the mechanical strength of the obtained carrier, but also stabilizes the charge imparting property over time as compared with the case of using other resins. Furthermore, even if the electrostatic latent image developer is stored or used for a long time under high temperature and high humidity conditions (for example, temperature: 30 ° C., humidity: 80%), the charge imparting property of the carrier hardly changes. Little deterioration of powder characteristics.

When a copolymer of styrene and alkyl (meth) acrylate is used, methyl methacrylate (MMA) is usually used as the alkyl (meth) acrylate.
In this case, the content molar ratio of the styrene repeating unit and the methyl methacrylate repeating unit in the copolymer was 5
0:50 to 95: 5 (preferably 55:45 to 90:10, particularly preferably
It is desirable to be in the range of 60:40 to 90:10,). By using the copolymer in the above range, while further improving the powder properties of the carrier under high temperature and high humidity conditions,
The initial charge imparting property is improved, and the property is maintained for a long time.

The number average molecular weight of the above copolymer is usually 5000
It is in the range of 0 to 200000, and the value of Mw / Mn is usually 1.0.
Is in the range of to 5.0, preferably in the range of 1.5 to 2.5.

In addition, this copolymer may contain other repeating units within a range that does not impair the characteristics of the carrier of the present invention.

The thickness of the intermediate layer can be appropriately set in consideration of the particle diameter of the core material and the layer thickness of the triboelectric charge control layer, but normally, (weight of intermediate layer forming resin) / (weight of core material) ) Is 0.2
~ 5.0, preferably 0.5 ~ 2.5 is appropriately adjusted. The thickness is usually 0.05 μm or more, preferably
It is 0.1 to 2.0 μm.

The carrier of the electrostatic latent image developer of the present invention has a triboelectric charge control layer on the above intermediate layer.

The triboelectric charge control layer comprises a fluorinated alkyl (meth) acrylate polymer.

It is necessary that the content of the fluorinated alkyl (meth) acrylate repeating unit in this layer is more than 50% by weight, and it is desirable that the content is 55% by weight or more.

When the content of the fluorinated alkyl (meth) acrylate repeating unit in this layer is 50% by weight or less, the charge imparting property of the carrier varies, so that the toner particles cannot always be positively charged. Further, the charge amount of the developer at the start of use becomes low (so-called rising is poor). In addition, the charge imparting property of the intermediate layer gradually becomes apparent by repeated use, so that the charge imparting property of the carrier cannot be stably maintained. Especially when used under high temperature and high humidity conditions, the above-mentioned fluctuation range may become large. Further, the scattering of the electrostatic latent image developer in the apparatus tends to increase.

By increasing the content of the fluorinated alkyl (meth) acrylate repeating unit to more than 50% by weight, the initial charge amount of the electrostatic latent image developer can be usually in the range of 10 to 40 μc / g, and, Since the charge amount is less likely to decrease even after repeated use, a clear visible image can be continuously obtained from the beginning of use of the electrostatic latent image developer, and further, so-called fog hardly occurs. Further, since various properties such as mechanical strength of the carrier are further improved, the durability of the electrostatic latent image developer containing the carrier of the present invention itself is also improved. If the content is lower than this value, the characteristics of the fluoroalkyl (meth) alkylacrylate polymer may not be sufficiently exhibited.

Further, by setting the content of the fluorinated alkyl (meth) acrylate polymer in this layer to 70% by weight or more (more preferably 75% by weight or more), various properties such as mechanical strength of the carrier are further improved. .

The fluorinated alkyl (meth) acrylate repeating unit in the fluorinated alkyl (meth) acrylate polymer forming the triboelectrification coating layer of the carrier of the electrostatic latent image developer of the present invention is represented by the following formula [I]. The repeating unit can be mentioned.

However, in the formula [I], R ¹ represents a hydrogen atom or a methyl group, and R ² represents a residue of the hydrogen of the hydroxyl group of the alcohol compound containing an alkyl group in which at least one hydrogen atom is substituted with a fluorine atom. It is a base.

Preferred examples of the repeating unit represented by the above [I] are shown below. These can be used alone or in combination of both.

However, in the formulas (a) and (b), R ¹ each represents a hydrogen atom or a methyl group, n and p each represent an integer of 1 to 8, and m and q
Each represents an integer of 1 to 19.

Examples of the alcohol compound capable of forming the residue represented by R ² in the above formula [I] include perfluoroalcohols having 1 to 18 carbon atoms (eg, perfluoromethanol, perfluoroethanol, perfluoropropanol, perfluoroalcohol). Fluorobutanol, perfluoropentanol, perfluorohexanol, perfluoroheptanol, perfluorooctanol, perfluorodecanol, perfluorostearyl alcohol); 1,1-dihydroperfluoroalcohol or trihydroperfluoro represented by the following formula Alcohol CF ₂ X (CF ₂ ) _n CH ₂ OH (where n is usually 0 or an integer of 1 to 16 and X is either a hydrogen atom or a fluorine atom. 1-dihydroperfluoroethanol, 1,1-dihydroperfluoro Lopropanol, 1,1-
Dihydroperfluorohexanol, 1,1-dihydroperfluorooctyl alcohol, 1,1-dihydroperfluorolauryl alcohol and 1,1-difluorostearyl alcohol and 1,1,2-trifluoroethanol, 1,1,3-tri Fluoropropanol, 1,1,4-trifluorobutanol, 1,1,5-trifluoropentanol and 1,1,18-trifluorostearyl alcohol are mentioned. ); Tetrahydroperfluoroalcohol represented by the following formula: CF ₃ (CF ₂ ) _n (CH ₂ CH ₂ ) (CF ₂ ) _m OH (where n is 0 or an integer of 1 to 15,
m is 0 or 1. As a specific example, 1,1,2,2
-Tetrahydroperfluoroethanol, 1,1,2,2-tetrahydroperfluoropropanol, 1,1,2,2-tetrahydroperfluorohexanol, 1,1,2,2-tetrahydroperfluorooctyl alcohol, 1,1, 2,2-tetrahydroperfluorolauryl alcohol, 1,1,2,2
-Tetrafluorostearyl alcohol and 2,2,3,3
-Tetrafluoropropanol. ); Other fluoroalcohols (eg, 2,2,3,3,4,4-tetrafluoropropanol, 1,1, ω-trihydroperfluorohexanol, 1,1, ω-trihydroperfluorooctanol, 1 , 1,1,3,3,3-hexafluoro-2-propanol); acetyl alcohol (eg, 3-perfluorononyl-
2-acetylpropanol, 3-perfluorolauryl-2-acetylpropanol); N-fluoroalkylsulfonyl-N-alkylamino alcohol (eg, N-perfluorohexylsulfonyl-N-methylaminoethanol, N-perfluorohexylsulfonyl) -N-butylaminoethanol, N-
Perfluorooctylsulfonyl-N-methylaminoethanol, N-perfluorooctylsulfonyl-N-
Ethylaminoethanol, N-perfluorooctylsulfonyl-N-butylaminoethanol, N-perfluorodecylsulfonyl-N-methylaminoethanol,
N-perfluorodecylsulfonyl-N-ethylaminoethanol, N-perfluorodecylsulfonyl-N-
Butylaminoethanol, N-perfluorolaurylsulfonyl-N-methylaminoethanol, N-perfluorolaurylsulfonyl-N-ethylaminoethanol and N-perfluorolaurylsulfonyl-N-butylaminoethanol).

Particularly, in the present invention, as the fluorine alkyl (meth) acrylate repeating unit, those described below are desirable.

However, R ¹ is a hydrogen atom or a methyl group.

The fluorinated alkyl (meth) acrylate polymer is
It may be a copolymer containing the above repeating unit alone, or may further contain another repeating unit. However, when other repeating units are contained, the above fluorinated alkyl (meth) acrylate repeating units in the copolymer are 50 mol% or more (preferably 55 mol%).
Above) it is desirable to include.

When the content of the repeating unit in the copolymer is lower than 50 mol%, the charge imparting property of the carrier may be increased when used under extremely severe conditions depending on the type of other repeating units or the styrene resin layer. It may fluctuate.

In the present invention, examples of other repeating units that can form a fluorinated alkyl (meth) acrylate-based polymer together with the above fluorinated alkyl (meth) acrylate repeating unit include a repeating unit derived from an aliphatic olefin. (Examples of aliphatic olefins, ethylene, propylene, butene-1), repeating units derived from halogenated aliphatic olefins (Examples of halogenated aliphatic olefins, vinyl chloride, vinyl bromide, vinyl iodide, 1,2 -Dichloroethylene, 1,2-dibromoethylene,
1,2-diiodinated ethylene, isopropenyl chloride, allyl chloride, allyl bromide, vinyl fluoride, vinylidene fluoride), repeating units derived from conjugated diene-based aliphatic diolefins (of conjugated diene-based aliphatic diolefins) Example,
1,3-butadiene, 1,3-pentadiene, 2-methyl-1,
3-butadiene, 2,3-dimethyl-1,3-butadiene, 2,4
-Hexadiene, 3-methyl-2,4-hexadiene),
Repeating units derived from aromatic vinyl compounds (examples of aromatic vinyl compounds, styrene, methylstyrene), repeating units derived from nitrogen-containing vinyl compounds (examples of nitrogen-containing vinyl compounds, 2-vinylpyridine) ,
4-vinylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5-methylpyridine, 4-butenylpyridine, 4-pentylpyridine, N-vinylpyridine,
4-vinylhydropiperidine, 4-vinyldihydropiperidine, N-vinyldihydropiperidine, N-vinylpyrrole, 2-vinylpyrroline, N-vinylpyrrolidine,
2-vinylpyrrolidine, N-vinyl-2-pyrrolidone,
N-vinylcarbazole) can be mentioned, and these can be used alone or in combination of two or more kinds.

As the above repeating unit, styrene, methylstyrene or methyl (meth) acrylate is particularly preferable.

Even when the solubility in the above-mentioned polymer or copolymer is high, when the molecular weight is too high, the viscosity of the solution becomes high, and pinholes are apt to occur during film formation. In the present invention, in order to secure properties such as good film-forming property, the intrinsic viscosity measured in methyl ethyl ketone (35 ° C) is usually in the range of 0.1 to 5.0 dl / g, preferably 0.4. Use polymers or copolymers within the range of ~ 0.8 dl / g.

In the present invention, the triboelectrification coating layer may be formed of a fluorinated alkyl (meth) acrylate-based polymer itself, or may be formed of a fluorinated alkyl (meth) acrylate-based polymer and another polymer. May be.

Examples of the other polymer include acrylic resins such as polymethylmethacrylate, polyethylmethacrylate, polymethylacrylate, and polyethylacrylate. Preferred is polymethylmethacrylate.

The thickness of the triboelectrification control layer can be appropriately set in consideration of the particle size of the core material and the layer thickness of the intermediate layer made of a styrene resin, but usually (weight of triboelectrification control layer)
/ (Weight of core material) is appropriately adjusted to be 0.2 to 5.0, preferably 0.54 to 2.5.

The thickness of the triboelectrification control layer obtained by using the resin forming the triboelectrification control layer in the above range relative to the core material is usually 0.05 μm or more (preferably within the range of 0.1 to 2.0 μm).
It is in.

When the content is within the above range, the initial charge amount of the electrostatic latent image developer becomes particularly good, and further, this charge amount does not fluctuate with time, and the powder characteristics are particularly high under high temperature and high humidity conditions. Tends to be good.

The above carrier, according to a method for producing a usual coated carrier, first forms an intermediate layer around the core material, and then,
It can be manufactured by forming a triboelectric charge control layer on this intermediate layer.

The total layer thickness of the intermediate layer and the triboelectric charge control layer of the carrier thus produced is usually 20 μm or less (preferably 5 μm or less).

The polyester resin used as the binder of the toner particles in the present invention is obtained by copolymerization of alcohol and carboxylic acid. As the alcohol used,
For example, ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, polyoxypropane (2,2)
Diols such as -2,2-bis (4-hydroxyphenyl) propane, 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol A And etherified bisphenol A's and other alcohol monomers.

As the polyhydric alcohol, besides the above dihydric alcohol, a trifunctional or higher polyhydric alcohol can be used together with the above dihydric alcohol or alone.

Examples of the trihydric or higher polyhydric alcohol among the polyfunctional monomers used here include, for example, sorbitol, 1,2,3,
6-hexanetetrol, 1,1-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5
-Pentatriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane,
Mention may be made of trimethylolpropane and 1,2,3-trihydroxymethylbenzene.

In the present invention, it is preferable to use a dihydric alcohol among the above polyhydric alcohols.

As the carboxylic acid, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid,
Gluraconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid and anhydrides of these acids can be mentioned.

As the polyfunctional carboxylic acid, a trifunctional or higher polyvalent carboxylic acid can be used in addition to the above dicarboxylic acid.

Examples of the trivalent or more polyvalent carboxylic acid monomer used here include 1,2,4-benzenetricarboxylic acid and 1,2,5.
-Benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,
2,5-Cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,
2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2
Mention may be made of methyl-2-methylenecarboxypropane, tetra (methylenecarboxy) methane, 1,2,7,8-octanetetracarboxylic acid, embol trimer and their acid anhydrides.

It is preferable to use an aromatic dicarboxylic acid among the above carboxylic acids, and it is more preferable to use one or more dicarboxylic acids selected from phthalic acid, isophthalic acid and terephthalic acid among the aromatic dicarboxylic acids. .

The polyester-based polymer, the polyhydric alcohol and polycarboxylic acid, the polyhydric alcohol compound and the organic carboxylic acid compound such that the hydroxyl group of the polyhydric alcohol and the carboxyl group of the carboxylic acid correspond to each other according to a usual method. It can be produced by reacting.

The toner particles may be composed of only the above polyester-based polymer as a binder, but other resins may be blended within a range that does not impair the properties of the polyester-based polymer. In this case, the content of the polyester polymer is usually 50% by weight or more (preferably 70% by weight or more).

Toner particles, the obtained polyester-based polymer and a colorant are added and mixed using a ball mill, and then,
It is manufactured through known steps such as kneading, pulverization and classification. If necessary, an additive (eg, offset preventive agent, charge control agent) usually used in the production of toner particles may be used.

The toner particles can be produced by a known method such as a spray drying method, an interfacial polymerization method, a suspension polymerization method and a solvent polymerization method, in addition to the above-mentioned production method.

The particle size of the toner particles produced by the above method is
Usually, it is in the range of 1 to 100 μm (preferably 5 to 30 μm).

Specific examples of the colorant contained in the toner particles include, in addition to carbon black used as a black pigment, a nigrosine dye, aniline blue, chalco oil blue,
Colored pigments such as chrome yellow, ultramarine blue, methylene blue, rose benval and phthalocyanine blue can be mentioned, and these can be used alone or in combination of two or more kinds.

It is important for the electrostatic latent image developer of the present invention to contain the above-mentioned toner particles and carriers, and normally, the content ratio of the toner particles, the carrier and the toner particles in the electrostatic latent image developer of the present invention is high. Is 1:99 to 10:90 (preferably 2:98 to 8:92)
Is within the range of.

[Effects of the Invention] In the electrostatic latent image developer of the present invention, the coating layer of the core material has a multi-layer structure of an intermediate layer and a triboelectrification control layer containing a fluorinated alkyl (meth) acrylate polymer, and the friction By using a carrier in which the fluorinated alkyl (meth) acrylate repeating unit has a limited specific value in the charge control layer and using a polyester-based resin as a binder for toner particles, first of all, the carrier is ) The thickness of the coating layer of the carrier can be made thinner than that of the conventional single layer coated carrier, and (2) even if the thickness of the coating layer is thin, the amount of charge with respect to the increase of the thickness of the coating layer The rise can be increased, (3) this charge imparting property can be maintained for a long period of time, and (4) the presence of the carrier even in an atmosphere of high temperature and high humidity. That it is less likely to decrease good charge-providing performance.

By using the carrier and toner particles in combination, the electrostatic latent image developer of the present invention has a proper amount of positive charge on the toner particles from the beginning of use, and this charge amount is Since it is less likely to decrease with repeated use, the charge quantity does not change with time under normal conditions or under severe conditions of high temperature and high humidity, and changes in powder properties with time Is reduced, and a clear electrostatic latent image can be visualized for a long period of time.

Further, since the toner particles are always charged appropriately, the non-charged toner and the like are less likely to be scattered in the apparatus, and further, the occurrence of fog due to the scattered toner and the difference in density between the front end and the rear end of the visible image are reduced. .

[Examples] Next, examples and comparative examples of the present invention will be described.

(Example 1) Production of carrier Mixed solvent of toluene and methanol (volume ratio = 9: 1) 4
20 g of methyl methacrylate / styrene copolymer (copolymerization molar ratio = 4: 6, Mw = 134000, Mw / Mn = 1.9) was dissolved in 00 ml to prepare a coating liquid for forming an intermediate layer.

Using this coating solution, a surface of 2 kg of ferrite core material (Nippon Iron Powder Co., Ltd .; F = 150, average particle size; 80 μm) is flow-rolled coating device (Okada Seiko Co., Ltd .; Spiracoat). To form an intermediate layer.

Next, 40 g of a fluorinated alkyl methacrylate polymer having a repeating unit represented by the following formula (1) was dissolved in 800 ml of toluene to prepare a coating liquid for the triboelectric charge control layer.

[Η] 0.49 dl / g (MEK, 35 ° C) A triboelectric charge control layer was formed on the above intermediate layer by a flow tumbling coating device with the obtained coating solution to produce a carrier having a positive charge imparting property. did.

Production of Toner Particles 332 g of phthalic acid, 90 g of polyoxypolypyrene (2,2) -bis (4-hydroxyphenyl) propane and 587 g of bisphenol A were mixed with a thermometer, a stirrer made of stainless steel, a nitrogen gas introduction pipe made of glass The flask was placed in a round bottom flask equipped with a flow-down condenser, the flask was set in a mantle heater, and nitrogen gas was introduced from a nitrogen gas introduction tube to raise the temperature in a state where the flask was kept in an inert atmosphere.

Then, 0.05 g of dibutyltin oxide was added and reacted at 200 ° C. while following the reaction at the softening point to produce a polyester resin.

100 parts by weight of this polyester resin, 10 parts by weight of carbon black (Regal 660R manufactured by Cabot Corporation), low molecular weight polypropylene (manufactured by Sanyo Kasei Co., Ltd., Viscole 66)
0P) 3 parts by weight and 2 parts by weight of ethylenebisstearoyl amide (Hoechst Wax C, manufactured by Hoechst) are mixed using a ball mill, kneaded, crushed and classified, and then finely divided hydrophobic silica powder "Aerosil R = 812" 0.4% by weight and 0.2 part by weight of zinc stearate were added to produce positively chargeable toner particles.

The average particle size of the obtained toner particles was 10 μm.

Production of Electrostatic Latent Image Developer An electrostatic latent image developer was produced by mixing the carrier and toner particles so that the content of the toner particles was 4% by weight.

(Example 2) In Example 1, instead of the fluorinated alkyl methacrylate polymer having the repeating unit represented by the formula (1), a fluorinated alkyl methacrylate polymer having the repeating unit represented by the following formula (2) was used. A carrier was prepared in the same manner except that the electrostatic latent image developer was manufactured in the same manner.

[Η] 0.50 dl / g (MEK, 35 ° C) (Example 3) In Example 1, instead of the fluorinated alkyl methacrylate polymer composed of the repeating unit represented by Formula (1), represented by Formula (3) below. A carrier was prepared in the same manner except that a fluorinated alkyl methacrylate polymer composed of repeating units was used, and an electrostatic latent image developer was manufactured in the same manner.

Example 4 In Example 1, a fluorinated alkyl methacrylate polymer having a repeating unit represented by the following formula (4) was used in place of the fluorinated alkyl methacrylate polymer having a repeating unit represented by the formula (1). A carrier was prepared in the same manner except that the electrostatic latent image developer was manufactured in the same manner.

[Η] 0.49 dl / g (MEK, 35 ° C.) (Example 5) In Example 1, instead of the fluorinated alkyl methacrylate polymer composed of the repeating unit represented by Formula (1), represented by Formula (5) below. A carrier was prepared in the same manner except that a fluorinated alkyl methacrylate polymer composed of repeating units was used, and an electrostatic latent image developer was manufactured in the same manner.

[Η] 0.60 dl / g (MEK, 35 ° C.) (Example 6) Instead of the toner particles used in Example 2, toner particles were prepared by using a polyester resin produced by the method described below. An electrostatic latent image developer was produced in the same manner except that was used.

Production of Polyester Resin In the polyester production process for producing the toner particles of Example 1, 180 g of 1,4-butanediol was used as the diol component, and isophthalic acid was used as the dicarboxylic acid component.
A polyester resin was produced in the same manner except that 45 g was used.

(Example 7) An electrostatic latent image developer was prepared in the same manner as in Example 4, except that the toner particles prepared in Example 6 were used.

Comparative Example 1 In Example 1, 12 g of the fluorinated alkyl methacrylate polymer and 28 g of polymethylmethacrylate used in Example 1 as a coating liquid for the triboelectric charge control layer were mixed with acetone.
A carrier was prepared in the same manner as described above, except that a coating liquid for triboelectric charge control layer dissolved in 800 ml of a toluene mixed solvent (mixing volume ratio = 9: 1) was used, and an electrostatic latent image developer was prepared in the same manner.

(Comparative Example 2) In Example 1, instead of the fluorinated alkyl methacrylate-based polymer, a fluorinated alkyl methacrylate-based polymer ([η] 0.
A carrier was manufactured in the same manner except that 60 dl / g (MEK, 35 ° C)) was used, and an electrostatic latent image developer was manufactured in the same manner.

(Comparative Example 3) In Example 1, a triboelectrification control layer was formed by using a coating solution prepared by dissolving 70 g of a fluorinated alkyl methacrylate polymer in 1.4 l of acetone directly on the surface of a core material without providing a styrene resin layer. A carrier was manufactured in the same manner as the carrier except that the electrostatic latent image developer was manufactured.

Comparative Example 4 In Example 1, 40 g of a composition having the composition described below
A carrier was produced in the same manner as described above except that the triboelectric charge control layer was formed using the coating liquid for triboelectric charge control layer dissolved in methyl ethyl ketone, and the electrostatic latent image developer was produced in the same manner.

N-perfluorooctyl sulfonyl-N-propyl methyl acrylate copolymer: 1 part by weight Methyl acrylate: 3 parts by weight Methyl methacrylate: 10 parts by weight Evaluation Antoanthrone pigment is used as a carrier generating substance, and as a carrier transporting substance. It was obtained by using a modified electrophotographic copying machine (U-Bix1550, manufactured by Konishi Rokusha Kogyo Co., Ltd.) equipped with a positively chargeable two-layer structure organic optical photoreceptor using a carbazole derivative. Continuous copying was performed with the electrostatic latent image developer.

Table 1 shows the results of the initial charge amount of the electrostatic latent image developer, the initial image, the final image, and the number of continuous copies (durability) of 70,000 sheets at this time.

Then, continuous copying was performed using the above apparatus under the conditions of a temperature of 30 ° C. and a humidity of 80%.

Table 2 shows the results of the initial charge amount of the electrostatic latent image developer, the initial image, the final image and the number of continuously copied sheets at this time.

The meanings of terms in Tables 1 and 2 are as follows.

"Dmax" represents the maximum image density, and was expressed as the relative density of the developed image when the image density of the original image was 1.3.

“Fog” was evaluated by the relative density of the developed image when the density of the original image was set to 0. The meanings of Table 1 and Table 2 are as follows.

No ………… Less than 0.01 Slightly …… 0.01 or more but less than 0.02 Yes ………… 0.02 or more For “durability”, the fog value of the developed image is 0.03 or more, or the Dmax value is 0.7 or less. Is the number of copies when The number of copies "more than 70,000" means 7
This means that even after copying 0000 sheets, neither the fog value nor the Dmax value reached the above-mentioned limit value.

As is clear from Tables 1 and 2, the electrostatic latent image developer of the present invention has an initial charge amount within a favorable range, so that the initial image is very clear. Further, there was little deterioration of the image due to repeated use of the electrostatic latent image developer, and continuous copying of 70,000 sheets or more was possible.

On the other hand, the electrostatic latent image developer produced in Comparative Example 1 has a remarkable decrease in the amount of charge due to its use, and the Dmax of the final image decreases. The electrostatic latent image developer produced in Comparative Example 2 had a poor start-up and insufficient initial charging. Further, the electrostatic latent image developer of Comparative Example 3 had insufficient carrier durability, and the characteristics of the electrostatic latent image developer changed with time. Therefore, all of these electrostatic latent image developers are used for continuous copying.
It did not reach 70,000.

Further, the electrostatic latent image developer manufactured in Comparative Example 4 could not visualize the electrostatic latent image because the charging property was not compatible with the electrostatic latent image.

Claims (8)

[Claims] 1. An electrostatic latent image developer comprising toner particles used for developing a negatively charged electrostatic latent image with positively charged toner particles and a carrier imparting a positive charge to the toner particles. The carrier comprises a core material and an intermediate layer made of a styrene resin and a triboelectrification control layer containing a fluorinated alkyl (meth) acrylate polymer coated on the core material in this order, and the triboelectrification control layer is provided. Containing more than 50% by weight of a fluorinated alkyl (meth) acrylate repeating unit, and the toner particles contain a polyester resin, an electrostatic latent image developer. 2. The content of the fluorinated alkyl (meth) acrylate polymer in the triboelectric charge control layer of the carrier is
The electrostatic latent image developer according to claim 1, which is 70% by weight or more. 3. The content of the fluorinated alkyl (meth) acrylate repeating unit contained in the fluorinated alkyl (meth) acrylate polymer in the triboelectric charge control layer of the carrier is 50 mol% or more. The electrostatic latent image developer according to item 1. 4. A static fluorinated alkyl (meth) acrylate polymer according to claim 1, wherein the fluorinated alkyl (meth) acrylate polymer has a repeating unit represented by the following formula (a) and / or (b). Electrostatic latent image developer; (However, in the formulas (a) and (b), R ¹ represents a hydrogen atom or a methyl group, n and p each represent an integer of 1 to 8, and m and q each represent an integer of 1 to 19). Represents.). 5. A styrene-based resin is a copolymer obtained by the reaction of styrene and methyl (meth) acrylate, and the content of styrene repeating units in the styrene-based copolymer is 50 mol% or more. Claim 1 which is
The electrostatic latent image developer according to item. 6. The electrostatic latent image developer according to claim 1, wherein the polyester resin is a resin obtained by reacting an aromatic dicarboxylic acid with a dihydric alcohol compound. 7. The electrostatic latent image developer according to claim 1, wherein the content of the polyester resin in the toner particles is 50% by weight or more. 8. The electrostatic latent image developer according to claim 1, wherein the content ratio of the toner particles to the carrier is in the range of 1:99 to 10:90. The electrostatic latent image developer according to item.