JPH02203356A - Carrier for electrostatic charge development - Google Patents

Abstract

PURPOSE:To obtain the carrier having high electrostatic chargeability by coating a carrier-core material with a specific copolymer or compsn. contg. this copolymer. CONSTITUTION:The carrier-core material is coated with the copolymer contg. at 20 to 95mol% at least one kind of the monomers selected from a group consisting of chlorotrifluoroethylene, tetrafluoroethylene and hexafluoropropylene and 80 to 5mol% at least one kind of the monomers selected from a group consisting of vinyl chloride and vinylidene chloride as essential components or the compsn. contg. this copolymer, by which the carrier for electrostatic charge development is constituted. Such carrier coating layer has excellent film strength and has a good adhesive property to the core material. The carrier which has not only the excellent durability but also the high rise of the electrostatic chargeability and the excellent electrostatic chargeability is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrostatic charge developing carrier (hereinafter referred to as carrier) which constitutes an electrostatic charge developer together with a toner in an electrophotographic copying machine.

In addition, in the following, “%゛” and “part” refer to
"mol %" and "parts by weight" respectively.

Conventional technology and its problems Traditionally, in two-component developers consisting of toner and carrier, vinylidene fluoride-tetrafluoroethylene copolymer, fluoroalkyl methacrylate, etc. have been used as the fluororesin that coats the negatively chargeable carrier. Polymers and the like have been proposed.

Among these, vinylidene fluoride-tetrafluoroethylene copolymer has good charging properties and excellent adhesion to the core material, but has the drawbacks of slow charging build-up and lack of stability. ing.

On the other hand, although fluoroalkyl methacrylate copolymers have a quick charge build-up and excellent stability, they have the disadvantage of poor adhesion to the core material and lack of durability.

Means for Solving the Problems As a result of repeated research in view of the problems of the prior art as described above, the present inventor has found that a copolymer consisting of a specific combination of specific monomers is excellent as a carrier film. It was discovered that it exhibits the following characteristics.

That is, the present invention provides a carrier for electrostatic charge development comprising a coating layer made of the following copolymers: (a) chlorotrifluoroethylene, tetrafluoroethylene and (b) 20 to 95 mol% of at least one monomer selected from the group consisting of hexafluoropropylene; and (b) 80 to 5 mol% of at least one monomer selected from the group consisting of vinyl chloride and vinylidene chloride. A carrier for electrostatic charge development comprising a carrier core material coated with a copolymer as an essential component or a composition containing the copolymer (hereinafter referred to as the first invention of the present application).

■In the carrier for electrostatic charge development, (a) 10 to 90 mol% of at least one monomer selected from the group consisting of chlorotrifluoroethylene, tetrafluoroethylene and hexafluoropropylene, (b) vinyl chloride and vinylidene chloride. 80 to 5 mol% of at least one monomer selected from the group consisting of; and (c) 1 to 30 mol % of at least one monomer having an unsaturated double bond copolymerizable with the above monomer. % or a composition containing the copolymer as an essential component (hereinafter referred to as the second invention of the present application).

The monomer (a) used in the first invention of the present application may be used alone (or two or more types may be used in combination. As the monomer (a), chlorotrifluoroethylene and tetrafluoroethylene are used. More preferred is fluoroethylene.

The monomer (b) used in the first invention of the present application may be used alone or in combination of two types.

The ratio of monomer (a) and monomer (b) in the copolymer used in the first invention of the present application is usually 20 to 95%, while the former is usually 20 to 95%.
The latter is 80-5%, and the former is more preferably 20-60%.
%, the latter is 40-80%. The former ratio is 2
If it is less than 0%, the chargeability will be insufficient and the performance as a carrier will not be fully demonstrated, whereas if it is more than 95%, the solubility will be low and it will be difficult to apply as a solution. .

The copolymer used in the second invention of the present application contains monomers in order to improve the glass transition temperature ('Tg), solvent solubility, charging characteristics, etc. of the copolymer, and to reduce cost. In addition to (a) and monomer (b), it also contains a monomer (C) having an unsaturated double bond copolymerizable with these monomers. Such monomer (C) is not particularly limited, but examples include the following: *Styrenes such as styrene, α-methylstyrene, and chloromethylstyrene; *Methyl acrylate, ethyl acrylate , propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, acrylic acid-2-
Chloroethyl, methyl α-fluoroacrylate, ethyl α-fluoroacrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, methacrylate α-substituted or unsubstituted alkyl (meth)acrylates such as hexyl methacrylate, octyl methacrylate, and 2-chloroethyl methacrylate; *Ethyl vinyl ether, 2-chloroethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, cyclohexyl Vinyl ethers such as vinyl ether and phenyl vinyl ether; *Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, vinyl pivalate, vinyl benzoate; *Methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, butyl vinyl ketone, phenyl Vinyl ketones such as vinyl ketone; *ethylene, propylene,
Olefins such as isobutyne, butadiene, isoprene; *N-vinylpyrrolidone, N-vinylcarbazole, 4
-Nitrogen-containing compounds such as vinylpyridine, acrylonitrile, methacrylatetrile; *vinyl fluoride, vinylidene fluoride, ethylene trifluoride, 2,2.2-trifluoroethyl methacrylate, 2,2,3.3-tetrafluoro Propyl acrylate, 2,2.2-trifluoroethyl-α-fluoroacrylate, 2,2.2-trifluoroethyl-α-chloroacrylate, vinyl-trifluoroacetate, 2,2,2゜3.3.3 Fluorine-containing monomers such as -hebutafluoropropyl vinyl ether, 1,1.2-)lifluorostyrene, p-monofluorostyrene, hexafluoroacetone, hexafluoroisobutyne, perfluoro(propyl vinyl ether), and the like.

The ratio of monomer (a):monomer (b):monomer (C) in the copolymer used in the second invention of the present application is usually 10 to 90%.
:5-80%=1-30%, more preferably 20
~50%: 40-70% = 5-20%. Monomer (
The reasons for defining the upper and lower limits in a) and (b) are almost the same as in the first invention of the present application. Monomer (C)
If the content is less than 1%, it is essentially no different from a binary copolymer, and the objectives of improving physical properties and reducing costs cannot be achieved. On the other hand, if it exceeds 20%, the amount of charge decreases and the stability of charge decreases, which is not preferable.

The molecular weight of the copolymer used in the present invention is usually about 5,000 to 5,000,000 degrees, more preferably about 10,000 to 1,000,000 degrees, as measured by gel permeation chromatography (in terms of polystyrene).

As a method for producing the copolymer, an ordinary radical polymerization method is employed, and bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, etc. are performed.

As a coating agent for the carrier core material, a composition obtained by blending the above-mentioned copolymer with other resins can also be used. More specifically, examples include blends with fluororesins such as vinylidene fluoride and vinylidene fluoride-tetrafluoroethylene copolymers, blends with other resins such as silicone resins and acrylic resins, silica powder, and charge control. Examples include blends with agents, surfactants, lubricants, etc. The use of these blends is based on the copolymer 5
It is preferably 0% or less. In order to prevent dehydrochlorination of the copolymer, stabilizers commonly used for stabilization such as vinyl chloride and vinylidene chloride can be used. Examples of such stabilizers include metal soaps, epoxy compounds, phosphorous esters, and polyols.

The coating on the carrier core material is formed in substantially the same manner as a conventional method. For example, the copolymer of the present invention or a mixture containing the copolymer and the blend material is dissolved or dispersed in an organic solvent to give a solid content concentration of 0.1 to 30% by weight, more preferably 1 to 5% by weight. A coating solution is prepared and coated on the core material by a dipping method, a dry spray method, a fluid spray method using a flow coater, etc., and then dried. If necessary, a heat treatment at a temperature of up to 100° C. may be performed after the coating is formed.

As the organic solvent, a wide variety of solvents can be used, unlike when conventional fluororesins are used.

More specifically, ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, and cyclohexanone; acetate ester solvents such as ethyl acetate, cellosolve acetate, and n-butyl acetate; tetrahydrofuran, dioxane, etc. cyclic ethers; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as tetrachloroethylene, trichloroethylene, methylene chloride, 1.1.2-trifluorotrichloroethane, 1,
Examples include fluorine-containing solvents such as 2-difluorotetrachloroethane, hexafluorometaxylene, and 1,1.2,3.4-hexafluorotetrachlorobutane.

These solvents may be used alone or in combination of two or more. From the viewpoint of evaporation rate, etc., a solvent having a boiling point of about 50 to 140°C is more preferable.

As the carrier core material used in the present invention, all known materials can be used, and there are no particular limitations. Specifically, metals that exhibit ferromagnetism, such as ferrite and magnetite, as well as iron, cobalt, and nickel; alloys or compounds containing these metals; alloy, for example, M
Suitable examples include so-called Heusler alloys such as n-Cu-AI and Mn-Cu-Sn, and metal oxides such as CrO2. The particle size of such a carrier is usually about 30 to 1000 μm, more preferably about 50 to 500 μm.

The thickness of the coating layer in a dry state is preferably about 0.1 to 5 μm, more preferably about 1 to 3 μm. When the thickness is less than 0.1 μm, durability is insufficient, and when it exceeds 5 μm, the adhesion of the coating film to the carrier core material decreases.

The carrier of the present invention is used in combination with known toners for electrostatic charge development. Such l-ner is obtained by dispersing a coloring agent in a binder resin.

Examples of the binder resin include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, α-methylene fatty acid monocarboxylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, and 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; Vinyl pyridines such as 2-vinylpyridine and 4-vinylpyridine; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and methyl isopropenyl ketone; ethylene, propylene, isoprene, Unsaturated hydrocarbons such as butadiene and their halides; homopolymers consisting of monomers such as chlorobrene and other unsaturated hydrocarbons;
Examples include copolymers of two or more of these, and mixtures of two or more of these homopolymers and copolymers. Alternatively, non-vinyl resins such as rosin-modified phenol-formalin resin, oil-modified epoxy resin, polyester resin, polyurethane resin, polyimide resin, cellulose resin, polyether resin, and mixtures of these non-vinyl resins and the above-mentioned vinyl resins are also included. It will be done.

Further, examples of coloring agents used in the toner include carbon black, nigrosine, aniline blue, calco oil blue, chrome yellow, ultramarine blue, methylene blue, rose bengal, and phthalocyanine blue.

The above toner may further contain additives such as waxes, silica, and zinc stearate, if necessary.

The carrier of the present invention and such toner are usually the former 1
The latter is mixed at a ratio of about 0.3 to 20 parts to 0.00 parts of the latter, and is used for developing electrostatic images such as the magnetic brush method and the cascade method.

Effects of the Invention The carrier coating layer made of the copolymer or the composition containing the copolymer used in the present invention has excellent film strength and good adhesion to the core material, so it not only has excellent durability but also resists charging. Provides a carrier with quick rise in properties and high chargeability.

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

Example 1 Chlorotrifluoroethylene (hereinafter referred to as CTFE) 4
A coating solution with a solid content concentration of 2% was prepared by dissolving a copolymer of 3% vinyl chloride (VCQ) and 57% vinyl chloride (hereinafter referred to as VCQ) with a molecular weight of 175,000 in a mixed solvent of methyl ethyl ketone/1,2-dichloroethane = 1/1. After the preparation, a dry film thickness of 2 μm was applied to spherical steel powder with a particle size of 200 μm as a carrier core material by a fluidized spray method according to a conventional method.
A carrier was obtained.

Example 2 CTFE/vinylidene chloride (hereinafter referred to as VdCQ) = 2
A copolymer having a molar ratio of 5/75 and a molecular weight of 120,000 was dissolved in 1.1.1-trichloroethane, and the same procedure as in Example 1 was carried out to obtain a carrier having a dry film thickness of 2 μm.

Example 3 A copolymer of CTFE/VCQ/vinylidene fluoride (hereinafter referred to as VdF) = 46.5/35/19.5 (mole ratio) and molecules till 10,000 was dissolved in methyl ethyl ketone, and the following procedure was carried out in the same manner as in Example 1. dry film thickness 2μm
gained a career.

Example 4 CTFE/vCQ/vinyl acetate = 52742/6
A copolymer having a molar ratio of 80,000 and a molecular weight of 80,000 was dissolved in a mixed solvent of ethyl acetate/methylethimeketone = 2/8, and a carrier having a dry film thickness of 2 μm was obtained in the same manner as in Example 1.

Example 5 Tetrafluoroethylene (hereinafter referred to as TFE)/VCQ
=42.8157. ' 2 (molar ratio) and the molecule ff
A copolymer of 160,000 was dissolved in a mixed solvent of methyl ethyl ketone/acetone = 1/1, and the same procedure as in Example 1 was carried out to obtain a carrier having a dry film thickness of 2 μm.

Example 6 A copolymer of TFE/VCQ/styrene = 33/49/18 (molar ratio) and a molecule of ff 175,000 was dissolved in a mixed solvent of methylethimeketone/trichloroethane = 2/1, and the following procedure was carried out in the same manner as in Example 1. A carrier having a dry film thickness of 2 μm was obtained.

Comparative Example 1 2, 2.3.3.4.4. A carrier having a dry film thickness of 2 μm was obtained in the same manner as in Example 1 except that 5.5-octafluoropentyl methacrylate polymer (molecular weight 100,000) was used.

Comparative Example 2 VdF/TFE-80/20 (mol) specific copolymer (
A carrier having a dry film thickness of 2 μm was obtained in the same manner as in Example 1, except that molecule [100000] was used and a mixed solvent of acetone/methyl ethyl ketone-1/1 was used.

Test Example 1 The following toner chargeability test was conducted using each carrier obtained in Examples 1 to 6 and Comparative Examples 1 to 2.

100 parts of styrene resin (trademark "Picolastic D125°", manufactured by Shell Standard Oil Co., Ltd.), carbon black (trademark "Regal 660R", manufactured by Cabot Corporation)
100 parts of the carrier described above is mixed with 100 parts of the above carrier to 10 parts of a toner having an average particle diameter of 10 μm, which is composed of a mixture of 10 parts and 5 parts of low molecular weight polypropylene (trademark "Viscol 660P", manufactured by Sanyo Chemical Industries, Ltd.), and the charge amount of the toner is determined. (Q/M:
(unit: μc/g) was determined by the blow-off method.

Further, after stirring this mixture of toner and carrier in a ball mill for 1000 hours, the toner charge fik (Q
/M (unit: μc/g) was measured again by the blow-off method.

The results are shown in Table 1.

1st Example Initial value 1 +20 2 +16 3 +23 4 +20 5 +19 6 +16 Comparative Example 1 +21 +36 +5 Table 1 After 1000 hours +16 +10 +19 +16 +14 +10 +2 From the results shown in Table 1, compared to the carrier according to the comparative example It is clear that the carrier of the present invention has excellent charging stability.

(that's all)

Claims (2)

[Claims] (1) In the carrier for electrostatic charge development, (a) 20 to 95 mol% of at least one monomer selected from the group consisting of chlorotrifluoroethylene, tetrafluoroethylene and hexafluoropropylene; (b) vinyl chloride and Electrostatic charge development comprising a carrier core material coated with a copolymer containing as an essential component 80 to 5 mol% of at least one monomer selected from the group consisting of vinylidene chloride, or a composition containing the copolymer. carrier. (2) In the carrier for electrostatic charge development, (a) 10 to 90 mol% of at least one monomer selected from the group consisting of chlorotrifluoroethylene, tetrafluoroethylene and hexafluoropropylene, (b) vinyl chloride and 80 to 5 mol% of at least one monomer selected from the group consisting of vinylidene chloride; and (c) 1 to 5 mol% of at least one monomer having an unsaturated double bond copolymerizable with the above monomer. A carrier for electrostatic charge development comprising a carrier core material coated with a copolymer containing 30 mol% as an essential component or a composition containing the copolymer.