JP2576537B2 - Carrier for developer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic brush developing carrier used for developing an electrostatic latent image in electrophotography and electrostatic recording. More specifically, the present invention relates to a magnetic brush developing carrier comprising a magnetic core material and a coating resin layer, which is excellent in chargeability, surface contamination resistance, mechanical strength, adhesion between the core and the coating layer, and the like.

2. Description of the Related Art In electrophotography, a photoconductive material such as selenium is used as a photoreceptor, an electric latent image is formed by various means, and the latent image is formed by a magnetic brush developing method or the like. A method of visualizing an image by attaching toner is generally adopted.

In this development step, carrier particles called carriers are used to impart an appropriate amount of positive or negative electricity to the toner. Carriers are generally broadly classified into coated carriers and uncoated carriers.The former is superior when considering the life of the developer, so various types of coated carriers have been developed and put into practical use. Have been.

Problems to be Solved by the Invention There are various characteristics required for the coat carrier, but particularly important characteristics are appropriate chargeability, impact resistance, abrasion resistance, and good adhesion between the core and the coating material. And uniformity of charge distribution.

In view of the above-mentioned required characteristics, conventionally used coat carriers still have problems to be improved, and the perfect ones are not known at present. For example,
Fluorinated vinyl polymers are excellent in surface contamination resistance, but have problems in adhesion to the core.Acrylic polymers are satisfactory in mechanical strength and adhesion to the core, but they are It is said that there is a problem in surface contamination and chargeability. In any case, at present, it is necessary to use a coating material having advantages and disadvantages.

Accordingly, it is a primary object of the present invention to provide a novel magnetic brush developing carrier used for developing an electrostatic latent image in electrophotography and electrostatic recording.

Another object of the present invention is that the charge rising speed is high and the surface contamination resistance is good, so that the charge amount during running does not decrease, and as a result, fog does not occur early, and there is no in-machine contamination. An object of the present invention is to provide a magnetic brush developing carrier having excellent adhesion between a core material and a coating layer.

Means for Solving the Problems The present inventors have conducted various studies and studies to improve the various contacts of the conventional developer carrier, and as a result, it was found that the use of a specific coating material was The inventors have found that the present invention is effective in improving various required characteristics, and have completed the present invention.

That is, the present invention comprises, as an essential component, a copolymer of vinylidene fluoride and trifluoroethylene, and as another component, (1) a polymer or copolymer of an acrylate ester and / or a methacrylate ester, or ( 2) A carrier for a negatively chargeable developer, wherein the magnetic core material as a core substance is coated with a coating material containing any of a copolymer of trifluoromonochloroethylene and vinyl chloride.

The copolymer of vinylidene fluoride and trifluoroethylene as a coating material for the carrier according to the present invention has a chargeability enough to withstand practical use even when used alone, and has properties of a coat film. In order to increase the adhesion between the core and the core, it is effective to use an acrylic ester polymer or a trifluoromonochloroethylene monovinyl chloride copolymer in combination.

Vinylidene fluoride-trifluoroethylene copolymer,
Polymer or copolymer of acrylic acid ester and / or methacrylic acid ester [hereinafter referred to as (meth) acrylic acid-based polymer. ] Or the mixing ratio with the trifluoromonochloroethylene copolymer is usually 99: 1 to 20:80 by weight.
Is appropriately adjusted according to the charge rising speed and the charge decay speed of the toner to be used.

The vinylidene fluoride-trifluoroethylene copolymer used in the present invention is polymerized by emulsion or suspension polymerization.

Examples of the monomer used for the (meth) acrylic ester polymer used in the present invention include esterified products of acrylic acid or methacrylic acid with various alcohols. And, as specific examples of the alcohol, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol,
Alkyl alcohols such as hexadecyl alcohol; halogenated alkyl alcohols obtained by partially halogenating these alkyl alcohols; alkoxyalkyl alcohols such as methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol and ethoxypropyl alcohol; benzyl alcohol Phenylethyl alcohol; aralkyl alcohols such as phenylpropyl alcohol; alkenyl alcohols such as allyl alcohol and crotonyl alcohol.

Examples of the monomer used for producing the (meth) acrylic ester polymer according to the present invention include one or more of the above acrylic monomers. If necessary, one or more other copolymerizable monomers may be used. Species or two or more species may be used. In this case, it is desirable that the acrylic monomer accounts for 25% by weight, preferably 50% by weight or more of all monomers. Specific examples include the following compounds.

That is, styrene and its derivatives, for example, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene,
Alkyl styrenes such as propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, octyl styrene, halogenated styrenes such as chlorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene, nitrostyrene, acetylstyrene, methoxystyrene, etc. No.

Also polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, α
-Addition polymerizable unsaturated aliphatic monocarboxylic acids such as methyl crotonic acid, α-ethyl crotonic acid, isocrotonic acid, tiglic acid, ungeric acid, or maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid And addition-polymerizable unsaturated aliphatic dicarboxylic acids such as dihydromuconic acid.

In addition, those obtained by metal salification of these carboxylic acids can be used, and the metal salification can be performed after the polymerization is completed.

Further, esterified products of the above-mentioned addition-polymerizable unsaturated carboxylic acid with alcohols such as alkyl alcohols, halogenated alkyl alcohols, alkoxyalkyl alcohols, aralkyl alcohols and alkenyl alcohols may be mentioned.

Further, amides and nitriles derived from the above addition-polymerizable unsaturated carboxylic acids; aliphatic monoolefins such as ethylene, propylene, butene, and isobutylene; vinyl chloride, vinyl bromide, vinyl iodide, 1,2-dichloroethylene. , Halogenated aliphatic olefins such as 1,2-dibromoethylene, 1,2-diiodoethylene, isopropenyl chloride, isopropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride, and vinylidene fluoride ; 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 And conjugated diene-based aliphatic diolefins such as

Further, vinyl acetates, vinyl ethers, and nitrogen-containing vinyl compounds such as vinyl carbazole, vinyl pyridine, and vinyl pyrrolidone are exemplified.

The copolymer of trifluoromonochloroethylene and vinyl chloride used in the present invention is polymerized by emulsion or suspension polymerization.

The core material used in the carrier of the present invention includes:
Iron powder, iron oxide powder, carbonyl iron powder, magnetite, magnetic materials such as nickel and ferrite powder can be exemplified, usually 10 ~ 500μ as a carrier
Of a size such that the particle size is

The carrier particles of the present invention are obtained by subjecting the above-mentioned core material to a surface treatment with the polymer (including a copolymer) according to the present invention as described above, and forming the copolymer on the surface of the core material by chemical bonding or adsorption. By forming a coating layer of

For surface treatment of the core material, for example, the core material is immersed in a solution obtained by dissolving one or more of the above polymers in a suitable solvent, and then desolvating,
Drying, high temperature baking method, or floating the core material in a fluidized bed, spray coating the polymer solution, drying,
A high-temperature baking method or the like can be used. In these methods, high-temperature baking is not always necessary.

The coating layer of the polymer is usually 0.05 to 3.
It is preferably 0% by weight.

The carrier of the present invention thus obtained is mixed with a toner and used as a developer for developing an electrostatic latent image.

As the toner, any negatively chargeable toner usually used in electrophotography in which a colorant is dispersed in a binder resin can be used, and is not particularly limited.

According to the carrier for developing a magnetic brush of the present invention, the following various effects can be achieved based on the magnetic core material being coated with a specific polymer.

First, since the charge rising speed is high and there is no decrease in the amount of charge during running, there is no early generation of fog or contamination inside the machine, and the adhesion between the core material and the coating is excellent (internal damage of the coating layer). No peeling due to the toner), high mechanical strength, and low surface energy of the coating material prevents toner contamination, so that the life of the carrier and thus the life of the developer can be extended,
Further, it can be manufactured by a simple process such as immersion in a solution, spray application of the solution, or heat treatment as necessary.

Examples Hereinafter, the present invention will be described more specifically with reference to Examples.
However, the present invention is not limited by these examples.

Example 1 16 parts by weight of a copolymer of vinylidene fluoride and trifluoroethylene (monomer ratio: about 8/2, intrinsic viscosity η _inh = 1.2) and 4 parts by weight of polymethyl methacrylate (Mw = 50,000) were added to 100 parts by weight of dimethyl This was dissolved in formamide, and this solution was subjected to an average grain size of 100 using a reduced pressure kneader coater.
The carrier according to the present invention was obtained by coating 2,000 parts by weight of a spherical iron oxide powder of μm.

Comparative Example 1 In Example 1, except that the copolymer of vinylidene fluoride and trifluoroethylene was replaced with vinylidene fluoride homopolymer (KF # 1000, η _inh = 1.0) manufactured by Kureha Chemical Co., Ltd. In the same manner as in Example 1, a control carrier was obtained.

Example 2 7 parts by weight of the same copolymer of vinylidene fluoride and trifluoroethylene and 13 parts by weight of a copolymer of trifluoromonochloroethylene and vinyl chloride (FPC-461, manufactured by Firestone) as in Example 1 It was dissolved in dimethylformamide, and this solution was coated on 2000 parts by weight of ferrite powder having an average particle size of 60 μm using a fluidized bed coating apparatus to obtain a carrier according to the present invention.

Each carrier obtained in Examples 1-2 and Comparative Examples 1-2
It comprises 1000 parts by weight and a positively charged positive toner [styrene-butyl acrylate copolymer, carbon black, nigrosine-based charge control agent (Bontron N-04, manufactured by Orient Chemical Co., Ltd.)]. 30 parts by weight were mixed to prepare a developer. Xerox 1065 (OPC released in the US and Europe)
A continuous copying test was performed using a copying machine equipped with a belt, and the results shown in the following table were obtained.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Koichi Kumashiro 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (72) Inventor Takayoshi Aoki 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. In-house (56) References JP-A-61-277967 (JP, A) JP-A-62-153962 (JP, A) JP-A-51-227085 (JP, A) JP-A-59-554215 (JP, A) JP-A-61-217068 (JP, A) JP-A-62-80669 (JP, A)

Claims (3)

(57) [Claims] 1. A carrier for a developer, comprising a magnetic core material coated with a coating material containing a copolymer of vinylidene fluoride and trifluoroethylene as an essential component. 2. A 99: 1 weight ratio of a copolymer of vinylidene fluoride and trifluoroethylene and a polymer or copolymer of acrylate and / or methacrylate.
The carrier for a developer according to claim 1, wherein the carrier is contained in a ratio of up to 20:80. 3. A composition comprising a copolymer of vinylidene fluoride and trifluoroethylene and a copolymer of trifluoromonochloroethylene and vinyl chloride in a weight ratio of 99: 1 to 20:80. The carrier for a developer according to claim 1.