JPH0623862B2 - Coated developer carrier - Google Patents

Description

The present invention relates to a coated developer carrier for electrophotography.

[Conventional technology]

Conventionally, in an electrophotographic electrostatic image developer comprising a carrier and a toner, the wear resistance of the carrier is improved,
In order to prevent the toner from accumulating in the carrier, a resin coating layer containing fluorine is provided on the surface of the carrier (Japanese Patent Laid-Open Nos. 48-52239, 49-123037 and 59-53857). See each bulletin).

[Problems to be solved by the invention]

However, the conventional carrier has poor adhesion between the resin coating layer and the core material, and lacks the triboelectrification stability and fluidity required for the carrier. It is rare.

An object of the present invention is to provide a coated developer carrier for electrophotography, which has stable triboelectric charging properties, good fluidity and abrasion resistance.

[Means for solving problems]

The present invention provides a crosslinked product of a vinylidene fluoride copolymer having a functional group, which is composed of a unit based on vinylidene fluoride and a unit based on a specific vinyl monomer having a hydroxyl group, a carboxyl group or a glycidyl group, or The present invention relates to a coated developer carrier in which a core material has a coating layer made of a crosslinked product of a mixture of the copolymer and an acrylic resin.

[Operation and Example]

The coating layer in the present invention comprises a vinylidene fluoride copolymer having a functional group, which is composed of a unit based on vinylidene fluoride and a unit based on a specific vinyl monomer having a hydroxyl group, a carboxyl group or a glycidyl group ( Hereinafter, a fluorocopolymer) or a resin coating obtained by adding a crosslinking agent to a mixture of the fluorocopolymer and an acrylic resin is applied to the core material by spray coating and cured.

(See Japanese Patent Application No. 58-175123 and Japanese Patent Publication No. 62-60406 for the components and composition of the fluorine-containing copolymer.)
Are described in detail in.

The fluorine-containing copolymer is usually vinylidene fluoride 50 to 99 mol%, preferably 65 to 85 mol% and a vinyl monomer having a functional group 1 to 50 mol%, preferably 1 to 10 mol%, or vinylidene fluoride. 50-99 mol%, preferably 65-85 mol%, vinyl monomer having a functional group 1-50 mol%, preferably 1-
10 mol% and less than 30 mol% of fluoroolefins other than vinylidene fluoride, preferably 10 to 25 mol%.

The molecular weight of the fluorocopolymer having vinylidene fluoride as a main component and having a functional group measured by gel permeation chromatography (GPC, polystyrene standard) is
It is usually in the range of 10,000 to 500,000. The vinyl monomer having the functional group is usually represented by the formula: CF ₂ ═CFO _k (CF ₂ ) _m (CH ₂ ) _n X (wherein X is a hydroxyl group, a carboxyl group or a glycidyl group, and k is 0 or 1). , M is an integer of 0 to 10, n is an integer of 0 to 4 (provided that X is a hydroxyl group, 1 to 4), a compound represented by the formula: CH ₂ ═CHO (CH ₂ ) _n X (In the formula, X and n are the same as above.), Formula: CH ₂ = CYCOO (CH ₂ ) _p X (In the formula, Y is hydrogen or a methyl group, p is an integer of 1 to 4,
X is the same as above. ) Or a compound represented by the formula: CH ₂ = CYCOOH (wherein Y is the same as the above).

The fluoroolefin other than vinylidene fluoride is usually tetrafluoroethylene, chlorotrifluoroethylene, monofluoroethylene, trifluoroethylene, hexafluoropropene, lower fluoroalkyl vinyl ether, etc., preferably tetrafluoroethylene or chlorotrifluoroethylene. is there.

As a method for producing a fluorinated copolymer, for example, each component, in the presence of a solvent, using a polymerization catalyst, -20 ~ 150 ℃,
A method such as emulsion polymerization, suspension polymerization or solution polymerization in an aqueous medium under a temperature condition of preferably 5 to 95 ° C. and a pressure condition of 0 to 30 kg / cm ² G or less can be adopted. The acrylic resin used in the present invention is usually an acrylate or methacrylate copolymer containing an alkyl group having 1 to 8 carbon atoms, and preferably an acrylate or methacrylate copolymer having a functional group. Acrylic resins include, for example, homopolymers or copolymers of methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl acrylate, etc., copolymers of the above acrylates or methacrylates with hydroxyethyl methacrylate, styrene, acrylonitrile, etc., as commercially available acrylic resins. Hitaroid 3004, Hitaloid 301
8, Hitaloid 3046C (all manufactured by Hitachi Chemical Co., Ltd.), Acridic A810-45, Acridic A814, Acridic 47-540 (all manufactured by Dainippon Ink and Chemicals) and the like, but not limited thereto.

The acrylic resin having a molecular weight (GPC) of 5,000 to 300,000 containing 50% by weight or more of methyl methacrylate is preferable from the viewpoint of compatibility with the fluorocopolymer.

The blending ratio of the fluorinated copolymer and the acrylic resin is preferably in the range of 99/1 to 40/60 by weight, particularly 99/1 to 50/50. The triboelectric chargeability can be adjusted arbitrarily within this range.When it is out of the range, the chargeability is insufficient and the image clarity becomes poor. The target image cannot be obtained. Further, in this case, toner is likely to be accumulated in the carrier.

The crosslinking agent is a compound having two or more groups capable of reacting with a functional group (hydroxyl group, carboxyl group or glycidyl group) usually contained in a fluorocopolymer to crosslink the fluorocopolymer. When the functional group is a hydroxyl group, the crosslinking agent is usually isocyanates, acid anhydrides and the like. When the functional group is a carboxyl group, it is usually an isocyanate, an amine, an amino resin, a compound containing a glycidyl group, or the like. When the functional group is a glycidyl group, it is usually an amine. Examples of isocyanates include, but are not limited to, hexamethylene diisocyanate, tolylene diisocyanate, hydrogenated tolylene diisocyanate and the like, and block isocyanates thereof. Examples of amines include, but are not limited to, diethylenetriamine, triethylenetetramine, xylenediamine, metaphenylenediamine, benzyldimethylamine, bisaminopropyltetraoxaspiroundecane, and the like. Examples of acid anhydrides include, but are not limited to, phthalic anhydride, pyromellitic dianhydride, and mellitic dianhydride. Examples of amino resins are alkyl etherified methylol melamine,
Examples thereof include, but are not limited to, alkyl etherified methylol urea and alkyl etherified benzoylguanamine. Examples of compounds containing a glycidyl group formula: Z-R ¹ -Z (wherein, Z is a glycidyl group, R ¹ is a divalent aromatic C6-10 alkylene group or a C 2 to 10 carbon atoms An aliphatic diepoxide or an aromatic diepoxide represented by the formula: (In the formula, R ² is a trivalent aromatic group and Z is the same as above.) And the like, but the aromatic triepoxide is not limited to these.

The compounding amount of the crosslinking agent is preferably adjusted so as to be 0.5 to 2 equivalents with respect to all functional groups in the fluorine-containing copolymer and the acrylic resin.

Different from conventional fluorine-containing copolymers, ordinary solvents can be widely used as the solvent. Specific examples include esters such as ethyl acetate, butyl acetate, isobutyl acetate, cellosolve acetate: acetone, methyl ethyl ketone,
Ketones such as methyl isobutyl ketone: Cyclic ethers such as tetrahydrofuran: Amides such as N-dimethylformamide and N-dimethylacetamide: Alcohols such as methyl alcohol, ethyl alcohol, butyl alcohol: Aromatic carbonization such as toluene and xylene Examples thereof include one kind or two or more kinds such as hydrogens.

The solid content concentration varies depending on the coating method etc., but is usually 0.1-1.
5% by weight, preferably 0.5-5% by weight is employed.

The resin coating thus prepared is usually applied to the core material by spray coating and cured at 5 to 200 ° C for several seconds to 7 days, but in practice, it is at 50 to 150 ° C for several minutes to several tens of minutes. It is preferable to cure in between.

Examples of the core material include silica sand, glass beads, aluminum-based particles, steel balls, and ferrite.

The carrier of the present invention can be used in combination with a conventionally used toner. Examples of such toners include resins such as polystyrene, styrene-acrylic acid copolymer, polyester, polyvinyl butyral, ethylene-vinyl acetate copolymer, polyamide and carbon black, spirit black, nigrosine, benzidine yellow, sproin yellow. Examples include toners including colorants such as Microlith Yellow, quinacridone, radamine, carmine, phthalocyanine blue, oil blue, alkali blue and ultra blue, and charge control agents and fluidizing agents.

The carrier of the present invention and the toner are usually a magnetic brush method,
It is used for developing electrostatic images such as the cascade method.

Examples 1-3 and Comparative Examples 1-2 of vinylidene fluoride 80 mol%, chlorotrifluoroethylene 15 mol% and _{CF 2 =} CFCF 2 CH 2 CH5 mol% of fluorine resin and 85% mol% methyl methacrylate, ethyl methacrylate 10 Acrylic resins containing 5 mol% of hydroxyethyl methacrylate and 50 mol% of hydroxyethyl methacrylate were dissolved in a mixed solvent of 1/1 by weight of n-butyl acetate / methyl ethyl ketone to 50% by weight, respectively, and the solid content ratios shown in Table 1 were used. And then cross-linking agent Coronate EH
(Nippon Polyurethane Industry Co., Ltd.): NCO value 1.1 equivalent to OH value 1 of fluororesin and acrylic resin and dibutyltin dilaurate as a curing accelerator in a ratio of 1 × 10 ⁻³ g to 1 g of the polymer. To prepare a coating stock solution, and then dilute it to a coating concentration of 1% by weight with a thinner of 1/1 weight ratio of n-butyl acetate and methyl ethyl ketone. Applied and dried at 50 ° C, then 80
After curing at 60 ° C. for 60 minutes, a carrier having a coating film having a film thickness of about 2 μ was obtained.

[Toner Charging Property] 100 parts by weight of the carrier obtained in each of Examples 1 to 3 and Comparative Examples 1 and 2 are 100 parts by weight of Picolastic D125 (styrene resin of Shell Standard Petroleum Co., Ltd.), and Peerless 155. 10 parts by weight of a toner having an average particle diameter of about 15μ, which is composed of a mixture of 5 parts by weight (manufactured by Columbia Ribbon and Manufacturing Co.) and 5 parts by weight of oil black BW (manufactured by Orient Chemical Industry Co., Ltd.), is mixed to obtain a toner. The charge amount was measured by the blow-off method. The results are shown in Table 2.

[Critical surface tension and friction coefficient]

The coating solution prepared in each of Examples 1 to 3 and Comparative Examples 1 to 2 was diluted with the same thinner as used in Example 1 to a coating concentration of 40% by weight, and the length was 100 mm, the width was 50 mm, and the thickness was 1 mm.
Each of the sufficiently degreased aluminum plates was coated with a brush, dried and cured at 80 ° C. for 60 minutes to obtain a coated plate of about 30 μm.

Using this coated plate as a test piece, a contact angle measuring instrument manufactured by Kyowa Kagaku Co., Ltd. was used to measure the contact angle using water, glycerin, diethylene glycol, methylene diiodide, and tetrachloroethylene, and the critical surface tension was determined using a Zisman plot. I asked for it.

The results are shown in Table 2.

Example 4 A paint was applied on the surface of a steel ball having a diameter of 200 μm and dried and cured by the same composition and method except that CF ₂ ═CFCF ₂ CH ₂ OH in Example 1 was replaced with hydroxybutyl vinyl ether. The toner charge amount of the obtained carrier was almost the same as the result of Example 1 shown in Table 2.

〔The invention's effect〕

As is clear from the results of the above examples, the carrier of the present invention is capable of adjusting the toner charge amount and has a small critical surface tension and a small friction coefficient, so that it has stable triboelectric chargeability and good flowability. And wear resistance.

Claims (2)

[Claims] 1. Crosslinking of a vinylidene fluoride copolymer having a functional group, which is composed of a unit based on vinylidene fluoride and a unit based on a compound represented by any one of the following formulas (1) to (4). A coated developer carrier in which a core material has a coating layer composed of a body. _{Formula: CF 2 = CFO k (CF} 2) m (CH 2) n X (1) ( wherein, X is a hydroxyl group, a carboxyl group or a glycidyl group, k is 0 or 1, m is an integer of 0, n represents an integer of 0 to 4 [wherein X is a hydroxyl group, 1 to 4].) Formula: CH ₂ ═CHO (CH ₂ ) _n X (2) (wherein, X and n are the same as above. .) _{formula: CH 2 = CYCOO (CH 2} ) p X (3) ( wherein, Y is hydrogen or a methyl group, p is an integer of 1 to 4,
X is the same as above. ) Formula: CH ₂ = CYCOOH (4) (In the formula, Y is the same as the above.) 2. A vinylidene fluoride copolymer having a functional group, which is composed of a unit based on vinylidene fluoride and a unit based on a compound represented by any one of the following formulas (1) to (4), and acrylic. A coated developer carrier in which a core material has a coating layer made of a crosslinked product of a mixture with a resin. _{Formula: CF 2 = CFO k (CF} 2) m (CH 2) n X (1) ( wherein, X is a hydroxyl group, a carboxyl group or a glycidyl group, k is 0 or 1, m is an integer of 0, n represents an integer of 0 to 4 [wherein X is a hydroxyl group, 1 to 4].) Formula: CH ₂ ═CHO (CH ₂ ) _n X (2) (wherein, X and n are the same as above. .) _{formula: CH 2 = CYCOO (CH 2} ) p X (3) ( wherein, Y is hydrogen or a methyl group, p is an integer of 1 to 4,
X is the same as above. ) Formula: CH ₂ = CYCOOH (4) (In the formula, Y is the same as the above.)