JPH05100471A - Toner for electrophotography - Google Patents

Abstract

PURPOSE:To provide a negatively chargeable toner for electrophotography having excellent flowability, caking resistance, chargeability and environmental stability, causing no black spotty image defect and capable of giving excellent image quality. CONSTITUTION:Surface-treated fine silica particles obtd. by treating hydrophobic fine silica particles having >=80% hydrophobic degree with a quat. ammonium salt compd. or a polymer having a quat. ammonium salt as a functional group are added as an additive to toner particles to obtain a negatively chargeable toner for electrophotography.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negatively chargeable electrostatic image developing toner (hereinafter referred to as an electrophotographic toner) used for developing an electrostatic image in electrophotography, electrostatic recording and the like. Regarding

[0002]

2. Description of the Related Art In electrophotography, an electrostatic charge image formed on a photoconductor is usually developed with a toner containing a pigment or the like, and the obtained toner image is transferred onto a transfer paper and fixed with a heat roll or the like. ,
On the other hand, the photoreceptor is cleaned again to form an electrostatic image. Dry developers used in such electrophotographic methods are roughly classified into one-component developers in which a toner itself in which a colorant is dispersed in a binder resin is used and two-component developers in which a carrier is mixed with the toner. In order to have process compatibility when a copying operation is carried out using these developers, the developer is required to have fluidity, anti-caking property, fixing property, charging property, cleaning property, etc. You need to be good. In particular, in order to improve the fluidity and the anti-caking property, it is often the case that inorganic fine powder is added to the toner.

However, the inorganic fine powder has a great influence on charging. For example, in the case of commonly used silica-based fine powder, the negative polarity is strong, and in particular, the chargeability of the negatively chargeable toner is excessively increased under low temperature and low humidity,
On the other hand, under high temperature and high humidity, there is a problem that a large difference is caused in the chargeability between the both because it takes in water to reduce the chargeability. As a result, poor density reproduction,
This sometimes caused background fog. Further, the dispersibility of the inorganic fine powder also greatly affects the toner characteristics, and if the dispersibility is not uniform, the desired characteristics cannot be obtained for the fluidity and caking resistance, or the cleaning becomes insufficient. Toner adhesion or the like may occur on the photoconductor, which may cause black dot image defects.

In order to improve these points, various proposals have been made to use surface-treated inorganic fine powder. For example, JP-A-46-5782 and JP-A-48
-47345 and JP-A-48-47346 describe that the surface of silica fine particles is subjected to a hydrophobic treatment. However, sufficient effects cannot always be obtained only by using these inorganic fine powders.

As a method of relaxing the negative chargeability of toner particles, a method of externally adding silica fine particles surface-treated with amino-modified silicone oil (Japanese Patent Laid-Open No. 64-733).
54) and a method of externally adding silica fine particles surface-treated with aminosilane and / or amino-modified silicone oil (Japanese Patent Laid-Open No. 1-237561). However, treatment with these amino compounds can suppress an excessive increase in charge of the negatively chargeable toner, but cannot sufficiently improve the environmental dependence of the silica fine powder itself. That is, although it is possible to slightly suppress the excessive negative chargeability of the silica fine powder after long-term use under low temperature and low humidity, since similar charge neutralization occurs even during long-term use under high temperature and high humidity, The dependence on the environment remains unchanged. Further, when silicone oil is used as the treatment agent, there is a drawback that silica has agglomerated during the treatment due to its high viscosity and the powder fluidity is deteriorated.

Furthermore, as a method for improving the triboelectric chargeability, storage stability and fluidity of the toner, it has a triboelectric chargeability different from that of the outer shell polymer of the toner particles, for example,
A method of externally adding silica fine particles coated with a polymer containing a monomer having a double bond to an amino group such as dimethylaminoethyl acrylate as a component to toner particles (Japanese Patent Laid-Open No. 64-6964). It is known.
However, this method is intended to impart triboelectric charging property, and like the above-mentioned amino compound, cannot sufficiently improve the environmental dependence.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances of the prior art. That is, an object of the present invention is to eliminate imparting triboelectric chargeability to the toner as much as possible, and improve the environmental dependence of the toner without adversely affecting the triboelectric chargeability of the toner. Another object of the present invention is to provide a negatively chargeable electrophotographic toner having excellent fluidity, anti-caking property and chargeability. Furthermore, it is another object of the present invention to provide a negatively chargeable electrophotographic toner which is less likely to cause black dot-like image defects and which can provide excellent image quality.

[0008]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that a negatively chargeable electrophotographic toner has a quaternary ammonium salt compound or a fourth functional group as a functional group. The inventors have found that this can be achieved by externally adding silica fine powder surface-treated with a polymer having a primary ammonium salt, and have completed the present invention. That is,
The structural feature of the present invention is that the external additive has a hydrophobicity of 80.
% Or more of the hydrophobic silica fine particles are treated with a quaternary ammonium salt compound or a polymer having a quaternary ammonium salt as a functional group, and surface-treated silica fine particles are added to the toner particles. It is found in electrostatic toners for electrophotography.

The present invention will be described in detail below. In the present invention, the surface-treated silica fine particles used as an external additive are hydrophobic silica fine particles having a hydrophobicity of 80% or more, preferably 90% or more, which are quaternary ammonium salt compounds or quaternary ammonium as a functional group. It is made by treating with a polymer having a salt.

As the hydrophobic silica fine particles having a hydrophobicity of 80% or more, those which have been subjected to a hydrophobic treatment with a hydrophobicizing agent such as a silane coupling agent can be used. Hydrophobicity is 8
When silica fine particles smaller than 0% are used, since the silica is easily affected by humidity and has large environmental dependence, the quaternary ammonium salt compound of the present invention or a quaternary ammonium salt as a functional group is used. Even if it is treated with the polymer, it is not preferable because a sufficient improvement effect cannot be obtained. The degree of hydrophobicity referred to here is measured by the "methanol titration test" as described below. That is, 0.2 g of silica fine particles added to 50 ml of water
Is titrated by dropwise addition of methanol from a buret until the entire amount of is wetted, at the end of which the value expressed by the percentage of methanol in the mixture of methanol and water.

Examples of the hydrophobizing agent that can be used for hydrophobizing the silica fine particles include, for example, alkylchlorosilanes such as methyltrichlorosilane, octyltrichlorosilane and dimethyldichlorosilane, dimethyldimethoxysilane and octyltrimethoxysilane. Examples thereof include alkylmethoxysilanes, hexamethyldisilazane, silicone oil and the like.

The polymer having a quaternary ammonium salt compound or a quaternary ammonium salt as a functional group used for the surface treatment of the hydrophobically treated hydrophobic silica fine particles has a quaternary ammonium salt structure. A homopolymer or copolymer containing a low-molecular compound having dialkylaminoalkyl acrylate or dialkylaminoalkyl methacrylate in the form of a quaternary ammonium salt as a monomer component (hereinafter, having a quaternary ammonium salt structure) A homopolymer or a copolymer).

Examples of the low molecular weight compound having a quaternary ammonium salt structure include the following general formulas (I) and (II).
The compounds represented by and (III) can be exemplified.

[0014]

[Chemical 1]

More specifically, the following compounds are exemplified.

[Chemical 2]

[0016]

[Chemical 3]

[Chemical 4]

Examples of homopolymers or copolymers having a quaternary ammonium salt structure include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutyl. Homopolymers such as aminoethyl (meth) acrylate and copolymers thereof with other copolymerizable monomers having a quaternary ammonium salt structure can be used. Examples of the monomer copolymerizable with dialkylaminoalkyl acrylate or dialkylaminoalkyl methacrylate include acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, styrene, vinyl acetate and the like.

The homopolymer or copolymer having a quaternary ammonium salt structure may be a dialkylaminoalkyl acrylate or dialkylaminoalkyl methacrylate alone, or together with one or more of the above-mentioned other copolymerizable monomers. The obtained homopolymer or copolymer is polymerized in the presence of a polymerization initiator to obtain a quaternary ammonium chloride, for example, alkyl benzenesulfonate such as methyl benzenesulfonate, methyl p-toluenesulfonate, or the like. It can be produced by quaternizing with an alkyl p-toluenesulfonate or the like.

The surface treatment method of the hydrophobized silica fine particles with the quaternary ammonium salt compound or the polymer having a quaternary ammonium salt as a functional group is
A quaternary ammonium salt compound or a polymer having a quaternary ammonium salt as a functional group is dissolved in a suitable solvent,
A method in which the solvent is dried after being added to silica fine particles to coat the surface is generally used. Specifically, it is preferable to use a device such as a kneader coater, a spray dryer, a thermal processor, or a fluidized bed. If necessary, pulverization / classification may be performed after drying.

The treatment amount of the quaternary ammonium salt compound or the polymer having a quaternary ammonium salt as a functional group varies depending on the type of silica fine particles, but is generally 0.1 to 300 with respect to the silica fine particles. %, Preferably 0.5 to 150%. However, in the present invention, the surface treatment of the silica fine particles with the quaternary ammonium salt compound or the polymer having a quaternary ammonium salt as a functional group is intended to improve the environmental dependency of silica and toner. However, it is not for imparting chargeability to the toner. Therefore, if the treatment amount for the silica fine particles is too large, the charge amount of the negatively chargeable toner may be reduced. Therefore, the treatment amount must be appropriately adjusted depending on the type of the silica fine particles.

In the present invention, the surface-treated silica fine particles added to the toner particles have an average primary particle diameter of 40 nm or less, preferably 20 nm or less.
The range of 16 nm or less is particularly preferable.

In the present invention, as the toner particles, known particles composed mainly of a binder resin and a colorant are used. The binder resin used is styrene,
Styrenes such as chlorostyrene, monoolefins such as ethylene, propylene, butylene, isoprene, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl esters such as vinyl butyrate, methyl acrylate, ethyl acrylate, butyl acrylate, acrylate Α-Methylene aliphatic monocarboxylic acid esters such as dodecyl acid, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, etc. Vinyl ethers,
Homopolymers or copolymers of vinyl ketone and the like such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone can be exemplified. Particularly, typical binder resins include polystyrene and styrene-alkyl acrylate copolymer. Examples thereof include polymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene and polypropylene. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.

Further, as the colorant of the toner, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate,
Lamp Black, Rose Bengal, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 12
2, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I. I. Pigment Blue 15: 1, Pigment Blue 15: 3 and the like can be exemplified as typical ones.

In the present invention, the silica fine particles surface-treated with a quaternary ammonium salt compound or a polymer having a quaternary ammonium salt as a functional group have no charge imparting function, so that a desired negative charge amount is obtained. In order to obtain the above, it is desirable that the toner particles contain a negatively chargeable charge control agent. As the charge control agent, known ones can be used, but it is particularly preferable to use an azo metal complex or a metal complex of salicylic acid or alkylsalicylic acid. In addition, known other components such as low molecular weight propylene, low molecular weight polyethylene, and offset preventive agents such as wax can be added. Further, the toner particles in the present invention may be a magnetic toner containing a magnetic material or a capsule toner. As the toner particles in the invention, those having an average particle diameter of 3 to 20 μm can be preferably used.

In the present invention, the surface-treated silica fine particles are added to the toner particles and mixed, and the mixing can be carried out, for example, by a V-type blender or a Henschel mixer. At this time, various additives may be added as required. Examples of these additives include fluidizing agents such as titania and alumina, and cleaning aids or transfer aids such as polystyrene fine particles, polymethylmethacrylate fine particles, and polyvinylidene fluoride fine particles. The amount of the surface-treated silica fine particles added is preferably 0.05 to 20% by weight, more preferably 0.1 to 5% by weight, based on the total amount of the toner.

In the present invention, the adhered state of the surface-treated silica fine particles on the surface of the toner particles may be merely mechanical adhesion or may be loosely adhered to the surface. Further, the entire surface of the toner particles may be covered or a part thereof may be covered. Further, the surface-treated silica fine particles may be partially coated as an aggregate, but are preferably coated in a single-layer particle state.

The electrophotographic toner of the present invention to which the surface-treated silica fine particles are added as described above can be used as a one-component developer or a two-component developer. When used as a two-component developer,
The surface-treated silica fine particles are not added to the toner particles in advance, but are added when the toner and the carrier are mixed,
The surface treatment may be performed simultaneously with the mixing of the toner and the carrier. As the carrier when used as a two-component developer, iron powder, glass beads, ferrite powder,
Nickel powder, or those whose surface is coated with a resin is used.

[0028]

In the present invention, the hydrophobic silica fine particles surface-treated with the quaternary ammonium salt compound or the polymer having the quaternary ammonium salt as a functional group as described above are externally added to the negatively chargeable toner. By so doing, the charge control function of the quaternary ammonium salt structure substance works without impairing the powder fluidity of the silica fine particles, and the excessive negative chargeability of the silica fine particles and the toner particles under low temperature and low humidity is suppressed. In addition, stable chargeability can be maintained even under high temperature and high humidity. Especially when a homopolymer or a copolymer having a quaternary ammonium salt structure is used as a treating agent,
Adsorption to the hydrophobic silica surface is good, and because it is resin coated, desorption of the processing agent does not easily occur during use of the developer,
Stable performance is exhibited over a long period of time, and the life of the developer can be extended. Further, since the silica fine particles have a function of reducing the frictional force, it is possible to improve the cleaning property and obtain a high-quality image without white spots or fogging. Since such a dry toner has high fluidity, it is particularly applied to a thin layer developing method in which a thin layer of toner is formed on a developing roll for development, or a high speed developing method for developing a latent image moving at high speed. When you do, the effect becomes remarkable. As the cleaning means, cleaning by blade pressure bonding, web fur brush cleaning, or the like can be used. Particularly, in the residual toner cleaning method by blade pressure bonding, the dry toner of the present invention exhibits excellent effects.

[0029]

The present invention will be described in more detail with reference to the following examples. In the following description, all "parts" mean "parts by weight" unless otherwise specified.

Example 1 Preparation of treated silica fine particles: As a quaternary ammonium salt compound, 1 part of the compound shown in I-9 above was dissolved in 1000 parts of ethyl alcohol to give an average primary particle diameter of 16 nm and a hydrophobicity of 84%. After stirring and mixing with 100 parts of the hydrophobic silica, the solvent ethyl alcohol was removed to obtain treated silica fine particles.

Production of toner particles: Styrene-butyl acrylate copolymer (80/20) 100 parts Carbon black (Regal 330 manufactured by Cabot) 10 parts Low molecular weight polypropylene (Viscole 660P manufactured by Sanyo Kasei) 5 parts Azochrome complex (preserved) Tsuchiya Chemical Co., Ltd., Spiron Black TRH) 1 part The above components were melt-kneaded with a Banbury mixer, cooled, pulverized with a jet mill, and further classified with a classifier to obtain a toner having an average particle size of 11 μm. Externally added toner was obtained by dispersing and mixing 1 part of the treated silica fine particles with 100 parts of the toner by a blender.

Production of carrier: A spherical iron oxide powder having an average particle diameter of 85 μm was added to a methyl methacrylate polymer (weight average molecular weight of about 85% by weight based on 0.8% by weight of the iron oxide powder).
000) using a fluidized bed coating device to a film thickness of about 1.
It was coated to a thickness of 2 μm to obtain a carrier. Preparation of developer composition: 5 parts of the above toner and 100 carriers
Parts were mixed to prepare a developer composition.

Example 2 Using the toner external additive of Example 1, hydrophobic silica having a hydrophobicity of 95% was used to obtain a toner under the same conditions as in Example 1 and mixed with the same carrier. A developer composition was prepared. Example 3 In the toner external additive of Example 1, the average primary particle diameter was 7 n
m using hydrophobic silica having a hydrophobicity of 82%, Example 1
Toner was obtained under the same conditions as above and mixed with the same carrier to prepare a developer composition. This toner showed very good powder flowability. Example 4 A toner was obtained under the same conditions as in Example 1 except that the compound shown in I-8 above and dichloromethane as a solvent were used as the quaternary ammonium salt compound of Example 1. To prepare a developer composition.

Comparative Example 1 Toner under the same conditions as in Example 1 except that hydrophobic silica in which the treatment of the quaternary ammonium salt compound was omitted was used in the toner external additive of Example 1. Was obtained and mixed with the same carrier to prepare a developer composition.

Comparative Example 2 In the toner external additive of Example 1, aminosilane NH ₂ CH ₂ CH ₂ was used instead of the quaternary ammonium salt compound.
Toner was obtained under the same conditions as in Example 1 except that hydrophobic silica treated with NHCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ was used and mixed with the same carrier to prepare a developer composition. The thing was prepared.

Comparative Example 3 The same as Example 1 except that in the toner external additive of Example 1, hydrophobic silica treated with amino-modified silicone oil was used instead of the quaternary ammonium salt compound. A toner was obtained under the conditions of 1 and mixed with the same carrier to prepare a developer composition.

Comparative Example 4 Same as Example 1 except that hydrophilic silica (# 130, manufactured by Nippon Aerosil Co., Ltd.) was used in place of the hydrophobic silica in the toner external additive of Example 1 to obtain treated silica. A toner was obtained under the conditions of 1 and mixed with the same carrier to prepare a developer composition.

Example 5 Production of treated silica fine particles: A dimethylaminoethyl methacrylate / butyl acrylate / styrene copolymer (15/15/70) (molecular weight: 9000) was treated with p-toluenesulfonic acid for quaternary ammonium chloride treatment. Resin 3 parts Acetone 1000 parts Hydrophobic silica 84% hydrophobicity (average primary particle size 16 nm) 100 parts The above components were mixed well, dissolved and dispersed, and then the solvent was removed in a fluidized bed. , Treated silica fine particles were obtained. Using the treated silica, a toner was obtained under the same conditions as in Example 1 and mixed with the same carrier to prepare a developer composition. An electronic copying machine (FX59
90, manufactured by Fuji Xerox Co., Ltd.) and a continuous copy test was conducted, and good copies were obtained even after copying 200,000 sheets.

Example 6 Preparation of treated silica fine particles: A resin prepared by subjecting a diethylaminoethyl methacrylate / methyl methacrylate copolymer (40/60) (molecular weight: 10,000) to a quaternary ammonium chloride treatment with p-toluenesulfonic acid 1. Part Acetone 500 parts Hydrophobic silica with a hydrophobicity of 84% (average primary particle diameter 16 nm) 100 parts The above components were well mixed, dissolved and dispersed, and then the solvent was removed in a fluidized bed to obtain treated silica fine particles. Obtained. Using the treated silica, a toner was obtained under the same conditions as in Example 1 and mixed with the same carrier to prepare a developer composition. An electronic copying machine (FX59
90, manufactured by Fuji Xerox Co., Ltd.) and a continuous copy test was conducted, and good copies were obtained even after copying 200,000 sheets.

Comparative Example 5 Preparation of treated silica fine particles: In the treated silica fine particles of Example 5, hydrophilic silica (# 1) was used instead of the hydrophobic silica.
No. 30, manufactured by Nippon Aerosil Co., Ltd., particle size 16 nm) was used to obtain a treated silica, and toner was obtained under the same conditions as in Example 5 and mixed with the same carrier to prepare a developer composition. ..

Copy test: A continuous copying test was carried out using an electrophotographic copying machine (FX-5990, manufactured by Fuji Xerox Co., Ltd.) using the dry developers of Examples and Comparative Examples. The results are shown in Table 1.

[0042]

[Table 1] (1) The charge amount is measured by a blow-off measuring device. (2) High temperature and high humidity means a copy test at 30 ° C and 90RH%. (3) Low temperature and low humidity is a copy test at 10 ° C and 15RH%. (4) "No problem" in toner storage stability means that coagulation does not occur at the 100,000th sheet. (5) Image quality defect “No problem” is caused by fog at the 100,000th sheet.
This means that there are no black spots. As is clear from this table, in the case of the example, compared to the case of the comparative example, when the copying is continued for a long time in the low temperature and low humidity region, the increase of the charge amount can be suppressed, and the image quality defect such as the density decrease can be suppressed. Can be suppressed. Further, the storage stability of the toner is improved without solidifying the toner in the copying machine.

[0043]

As is clear from the results shown in Table 1, in the present invention, by having the above-mentioned constitution, imparting triboelectric charging property to the toner is eliminated as much as possible, and the triboelectric charging property of the toner is lowered. The environmental dependence of the toner can be improved without adversely affecting the toner, and the toner has a negative chargeability excellent in fluidity, anti-caking property and chargeability. Therefore, by using the negatively chargeable electrophotographic toner of the present invention, it is possible to obtain an image of excellent image quality in which black-spotted image defects are unlikely to occur.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsuhiko Eguchi 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Zero Tsux Co., Ltd. Takematsu Plant (72) Inventor Yasuhiro Oya 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Fuji Zero Tux Co., Ltd. Takematsu Business (72) Inventor Hiroaki Yoshikawa 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Zero Tsux Co., Ltd. Takematsu Plant

Claims (2)

[Claims] 1. A negatively charging toner for electrophotography containing hydrophobic silica particles having a hydrophobicity of 80% or more treated with a quaternary ammonium salt compound or a polymer having a quaternary ammonium salt as a functional group. .. 2. The electron according to claim 1, wherein the polymer having a quaternary ammonium salt as a functional group is a quaternary ammonium chloride-treated dialkylaminoalkyl methacrylate or dialkylaminoalkyl acrylate. Negative charging toner for photography.