JPH0320751A - Electrostatic charge image developing carrier - Google Patents

Abstract

PURPOSE:To enhance film strength, adhesion to a core material, and chargeability characteristics of a carrier by coating the core material with a copolymer of specified 2 kinds of monomers or a composition of it. CONSTITUTION:The carrier is obtd. by coating the carrier core material with the copolymer of one or more monomers selected from a group of chlorotrifluoroethylene, tetrafluoroethylene, and trifluoroethylene, etc., in an amount of 45 - 90 mol % and one or more of monomers represented by the shown formula in an amount of 10 - 55 mol % as an essential component, and in the formula, R is alkyl, aryl, or the like. A composition of the copolymer can be used for the copolymer, and a chlorotrifluoroethylene-vinyl acetate copolymer and the like can be used for the copolymer.

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 "parts" all mean "mol %" and "ffiffl parts".

Conventional technology and its problems Traditionally, in two-component developers consisting of toner and carrier, the surface of the core material is coated with a (meth)acrylate polymer having a fluoroalkyl group in the side chain as a carrier that gives positive chargeability to the toner. Coated materials are known (for example, JP-A-53-97435). However, since this carrier has poor adhesion between the polymer used and the core material, there are problems in that the chargeability is decreased and the durability is not sufficient.

Furthermore, carriers coated with vinylidene fluoride copolymers are also known (for example, JP-A-60-17605
Publication No. 5). However, this carrier has a soft coating and is easily scratched, has poor adhesion, is not durable, and does not retain sufficient charge, causing so-called fogging and unevenness on copies. There is a problem.

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 made of a combination of specific monomers in specific amounts 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 film containing the following copolymers as essential components: "(a) chlorotrifluoroethylene, tetrafluoroethylene, trifluoroethylene and 45 to 90 mol% of at least one monomer selected from the group consisting of hexafluoropropylene and (b) the formula CH2-CHOOCR [wherein R is an alkyl group, a cycloalkyl group or an aromatic group] At least one monomer represented by 10
Carrier 7 = A carrier for electrostatic charge development in which a core material is coated with a copolymer containing ~55 mol% as an essential component or a composition containing the copolymer. ” The monomer (a) used in the present invention is chlorotrifluoroethylene, tetrafluoroethylene, trifluoroethylene and hexafluoropropylene. These monomers may be used alone, or two or more persimmons may be used in combination.

As the monomer (a), tetrafluoroethylene and chlorotrifluoroethylene are preferred, and chlorotrifluoroethylene is more preferred.

The alkyl group represented by R in the monomer (b) used in the present invention may be a linear or branched group that may be substituted with a halogen atom, etc.
Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, nonyl, decyl, undecyl, dodecyl, chloromethyl, and the like. Examples of the cycloalkyl group include cycloprobyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl.

Examples of aromatic groups include phenyl groups and naphthyl groups which may be substituted with alkyl groups, halogen atoms, hydroxyl groups, etc., such as phenyl, methylphenyl, chlorophenyl, p-tert-butylphenyl, and the like.

Specific examples of the monomer (b) include the following.

C H 2 = C H O O C C H 3,C
H2 C H2 CH2 CH2 C H2 CH2 C H 2 = C H 0 0 C C 2 H s , Straw C
HO O C C 3 Hv,=CHOOCC.
H9, = C H O O C C H (C H 3
) 2 , = C H 0 0 C C ( C
H 3 ) 3 ,=CHO'OC (CH2
)9 CH3,=CHOOC (CH2 )lOcH
3, C H 2 = C H O O C C
H 2 C (1 1 The following formula: R1 CH2 = CHOOCC-R2 l CH3 (R1 and R2 represent an alkyl group. However, the total number of carbon atoms in R1 and R2 is 7.) (manufactured by Shell Chemical Co., Ltd.), etc.).

These monomers (b) may be used alone or in combination of two or more.

Monomer (a) in the copolymer used in the present invention: Monomer (
The ratio of b) is usually 45-90%:55-10%, preferably 55-85%=45-15%, more preferably 60-80%:40-20%. If the blending ratio of monomer (a) is less than 45%, the amount of fluorine will be small, resulting in insufficient charging properties and the performance as a carrier will not be fully demonstrated, whereas if it exceeds 90%. has low solubility and poor applicability to carrier core materials.

The copolymer used in the present invention has a glass transition temperature (Tg) of the copolymer within a range that does not impair the properties of the copolymer.
), to improve solubility in solvents, charging characteristics, etc.
Other copolymerizable monomers may be included up to 30% of the total amount of monomers (a) and (b). Examples of such monomers include, but are not limited to, the following: *Styrenes such as styrene, α-methylstyrene, chloromethylstyrene, and chlorostyrene; *Methyl acrylate, ethyl acrylate , probyl acrylate, butyl acrylate, trifluoroethyl acrylate, pentafluoropropyl acrylate, methyl methacrylate, ethyl methacrylate, probyl methacrylate, butyl methacrylate, trifluoroethyl methacrylate, pentafluoropropyl methacrylate, α-Methyl fluoroacrylate, α-ethyl fluoroacrylate, α-probyl fluoroacrylate, α-butyl fluoroacrylate, trifluoroethyl α-fluoroacrylate, pentafluoroprobyl α-fluoroacrylate, α-chloroacrylate α-substituted or unsubstituted α-methyl acrylate, α-ethyl chloroacrylate, α-probyl chloroacrylate, α-butyl chloroacrylate, α-trifluoroethyl chloroacrylate, pentafluoropyropyr α-chloroacrylate, etc. Alkyl (meth)acrylates; *Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, probyl vinyl ether, butyl vinyl ether, 2.2.3.3-tetrafluoroprobyl vinyl ether, cyclohexyl vinyl ether; *Methyl vinyl ketone Vinyl ketones such as , ethyl vinyl ketone, probyl vinyl ketone, butyl vinyl ketone, phenyl vinyl ketone: *Ethylene, propylene,
Olefins such as isobutene, butadiene, isoprene; *N-methylpyrrolidone, N-methylcarbazole, 4
-Nitrogen-containing compounds such as vinylpyridine, acrylonitrile, and methacrylonitrile: *Norroolefins such as vinyl chloride and vinylidene chloride.

The glass transition temperature (T
g) is 50°C or higher, preferably 60°C or higher. If the temperature is lower than this, there is a risk that the film will soften or fuse during the manufacture of the carrier or use as a developer.

The molecular weight of the copolymer used in the present invention is 1 at 35°C.
, 1. The intrinsic viscosity when measured in 1-trichloroethane is about 0.01 to 2.0.

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. For suspension polymerization and solution polymerization, 1
, chlorine-based solvents such as 1.1-trichloroethane and 1,2-dichloromethane, alcohol-based solvents such as tert-butanol, ester-based solvents such as ethyl acetate, ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, Aromatic solvents such as toluene and xylene, 1,1
．． 2-trichloro1.2.2-trifluoroethane,
1.2-dichloro1.1.2.2. In the case of emulsion polymerization using one or more solvents such as fluorine-based solvents such as monotetrafluoroethane, CF3 (CF2)6
COONH4,H (CF2)b COONH4
, sodium dodecyl sulfate, and the like are used.

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, for example, 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 amount of these blend materials used is 5% of the copolymer.
The content is preferably 0% by weight or less.

The coating on the carrier core material is carried out 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 coat the solid content with a solid content of 0.1 to 30% by weight, more preferably 1 to 5% by weight. A solution is prepared, coated on the core material by a dipping method, a dry spray method, a fluidized spray method using a flow coater, etc., and dried. If necessary, a heat treatment at a temperature of up to 180° 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 probyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone; 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; methyl alcohol, ethyl alcohol, butyl alcohol, tert-
Alcohols such as butyl alcohol and isobrobyl alcohol; 1.1.2-trifluorotrichloroethane, 1,2-difluorotetrachlorethane, hexafluorometaxylene, 1,1,2,3.4-hexafluorotetra Examples include fluorine-containing solvents such as butane.

These solvents may be used alone or in combination of two or more. From the viewpoint of evaporation rate, etc., it is more preferable that the solvent has a boiling point of about 60 to 140°C.

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 Cr02. The particle size of such a carrier is usually about 30 to 1000 μm, more preferably about 50 μm.
It is about 500 μm.

The thickness of the coating layer in the dry state is 0. The thickness is preferably about 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 a toner is obtained by dispersing a colorant in a binder resin.

Examples of the binder resin include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-probyl acrylate, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, Esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, and 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; vinyl such as 2-vinylpyridine and 4-vinylpyridine Pyridines; 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; unsaturated hydrocarbons and their halides such as ethylene, propylene, isoprene, and butadiene; Examples include homopolymers made of monomers such as halogenated unsaturated hydrocarbons such as chloroprene, copolymers made of two or more of these persimmons, 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, lucooil 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. A carrier with excellent quantity retention can be provided.

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) 7
A copolymer (intrinsic viscosity: 0.52) consisting of 2% vinyl acetate and 28% vinyl acetate (hereinafter referred to as VAc) was mixed with ethyl acetate/1.1.
A 2.5% concentration coating was prepared by dissolving in 1-trichloroethane (1:1) mixed solvent. Using a flow coater (FL-MTN■, Freund Sangyo), the obtained coating liquid was applied to a carrier core material (DSPR-141, Dowa Iron Powder Industries Co., Ltd.) so that the dry film thickness was 2 μm.

Separately, styrene/n-butyl methacrylate copolymer (
Molar ratio: 85:15, molecular weight = 80,000, Tg: 65°C
) 100 parts, low molecular weight polypropylene (Viscol 66
0R, Sanyo Chemical Industries) and 5 parts of carbon black (Regal 330R, Cabot Corporation) were kneaded, pulverized, and classified to obtain a toner having an average particle size of 10 μm.

A developer was prepared by mixing 100 parts of the carrier obtained above and 3 parts of toner in a blender.

Example 2 CTFE65% and VAc as carrier raw materials
A developer was prepared in the same manner as in Example 1, except that a copolymer containing 35% (intrinsic viscosity: 0.66) was used.

Example 3 When producing a carrier, a copolymer consisting of 78% CTFE and 22% vinyl chloroacetate (intrinsic viscosity: 0.
A developer was prepared in the same manner as in Example 1, except that 42) was dissolved in 1.1.1-h-lichloroethane.

Example 4 When producing a carrier, a copolymer (intrinsic viscosity: 0.28) consisting of 55% CTFE, 35% vinyl versatate, and 10% cyclohexyl vinyl ether was dissolved in a mixed solvent of methyl ethyl ketone/ethyl acetate (1:1). A developer was prepared in the same manner as in Example 1, except that a developer was used.

Example 5 When producing a carrier, tetrafluoroethylene 7
5% of vinyl benzoate and 25% of vinyl benzoate (intrinsic viscosity: 0.39). 1. A developer was prepared in the same manner as in Example 1, except that a solution dissolved in a 1-trichloroethane/ethyl acetate (1:1) mixed solvent was used.

Example 6 When producing a carrier, a copolymer consisting of 55% CTFE and 45% vinyl bivalate (intrinsic viscosity: 0.
A developer was prepared in the same manner as in Example 1, except that 69) was dissolved in ethyl acetate.

Comparative Example 1 Example 1 except that a copolymer consisting of 80% vinylidene fluoride and 20% tetrafluoroethylene dissolved in a mixed solvent of methyl ethyl ketone/acetone (1:1) a was used when producing the carrier. A visual agent was prepared in the same manner as above.

Test Example 1 Toner charge amount (
Q/M (unit: μc/g) was determined using a blow-off charge measuring device (TB-200, Toshiba Chemical).

The results are shown in Table 1.

Table 1 Example Immediately after preparation After being left for 24 hours 1
+32 +222 +19
+10 3 +33 +254
+13. ．． +6 5 +28 +236
+10 +4 Comparative example 1 +44. +10 From the results shown in Table 1, it is clear that the carrier of the present invention has superior charging stability compared to the carrier according to the comparative example.

Test Example 2 After stirring the developers obtained in the above Examples and Comparative Examples for 300 hours using a pole mill, the surface of the carrier was observed using a scanning electron microscope. While no abnormality was observed in the coating, partial peeling was observed in the coating of the carrier of Comparative Example 1.

(that's all)

Claims (1)

[Claims] (1) In the carrier for electrostatic charge development, (a) 45 to 90 mol% of at least one monomer selected from the group consisting of chlorotrifluoroethylene, tetrafluoroethylene, trifluoroethylene, and hexafluoropropylene; b) Formula CH_2=CHOOCR [wherein R is an alkyl group, a cycloalkyl group, or an aromatic group. ] 10 to 55 mol% of at least one monomer represented by
A carrier for electrostatic charge development comprising a carrier core material coated with a copolymer having and as essential components or a composition containing the copolymer.