JPH02168275A - Carrier for electrostatic charge development - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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.

BACKGROUND ART Conventionally, in a two-component developer consisting of a toner and a carrier, the surface of a core material has been coated with a fluororesin as a carrier that imparts positive chargeability to the toner.

For example, a carrier coated with a copolymer of vinylidene fluoride and tetrafluoroethylene has been proposed (Japanese Patent Application Laid-open No. 176055/1983).

However, since this carrier does not have sufficient charging stability, it tends to cause so-called fog, unevenness, etc. on copies.

Also known is a carrier coated with a polymer containing 50% by weight or more of (meth)acrylate) having a fluoroalkyl group in the side chain or a composition containing the polymer (JP-A-Show). 61-120170). However, this carrier has problems in that the adhesion between the polymer used and the core material is poor, resulting in a decrease in chargeability and insufficient 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 having a film made of the following copolymer: Carrier m for electrostatic development formed by coating a carrier core material with a polymer or a composition containing the copolymer: and (1) 30 to 70 mol% of chlorotrifluoroethylene, 70 to 30 mol% of propylene, and copolymerized with these. A carrier core material is made of a copolymer obtained by copolymerizing a possible unsaturated double bond-containing monomer at a ratio of 0.1 to 20% by weight based on chlorotrifluoroethylene and propylene, or a composition containing the copolymer. Coated carrier for electrostatic charge development The copolymer of chlorotrifluoroethylene (CTFE) and propylene (Pr) used in the present invention is preferably 70 to 30 mol% of the former and 30 to 70 mol% of the latter, more preferably The former consists of 65 to 40 mol% and the latter 35 to 60 mol%. If the CTFE content in the copolymer is less than 30 mol%, the amount of charge will be low and its performance as a carrier will be insufficient, whereas if it exceeds 70 mol%, the adhesion to the core material will be poor. This is not preferable because the durability of the carrier is poor.

In addition, the copolymer used in the present invention may be used within a range that does not impair the properties of the copolymer, for example, 0.1 to 20% of the copolymer weight.
% of other copolymerizable unsaturated double bond monomers may be included as a third component. Examples of such monomers include the following.

(meth)acrylic monomers such as monomethyl methacrylate and trifluoroethyl methacrylate; -fluorine monomers such as tetrafluoroethylene, hexafluoroethylene, perfluoro(propyl vinyl ether), vinylidene fluoride, and vinyl fluoride; Vinyl ester polymers such as vinyl monoacetate and vinyl pivalate; monoethyl vinyl ether, cyclohexyl vinyl ether, 2. 2. 3. Vinyl ether monomers such as 3-tetrafluoropropyl vinyl ether; Olefin monomers such as styrene, ethylene, and isobutylene.

Alternatively, a monomer having a heterofunctional group such as hydroxybutyl vinyl ether, hydroxyethyl methacrylate, or glycidyl vinyl ether may be copolymerized, and the resulting copolymer may be applied to the core material and then crosslinked.

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

The usual radical polymerization method is used to produce the copolymer. Suspension, emulsification, and solution polymerization take place. Also,
The copolymers of the present invention can also be produced by radiation polymerization.

As a coating agent for the carrier core material, a composition obtained by blending the above-mentioned copolymer with Ike's resin or the like can also be used. For example, it may be blended with short-chain fluoroalkyl (meth)acrylate to adjust the amount of charge and the time until the amount of charge is saturated, or it may be blended with long-chain fluoroalkyl (meth)acrylate to prevent toner particles from adhering to each other. ) Can be blended with acrylates. Also,
If necessary, known additives such as silica powder, silicone resin, charge control agent, surfactant, and lubricant may be blended. The amount of these blend materials used is preferably 50% by weight or less of the copolymer.

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 obtain a solid content of 0.1 to 30% by weight, more preferably 1 to 5% by weight. ? A t rfl liquid is prepared, coated on the core material by a fluidized spray method using a flow coater, and dried. If necessary, a heat treatment at a temperature of up to 150° 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, and methyl isobutyl ketone; acetate ester solvents such as ethyl acetate, cellosolve acetate, and n-butyl acetate; ethers such as tetrahydrofuran and dioxane; and aromatic substances such as toluene and xylene. Group hydrocarbons: Examples include halogenated hydrocarbons such as chloroform, 1,1,1-1-lichloroethane, and perchloroethylene, but there are also other hydrocarbons that can dissolve the copolymer. If it exists, it can be used. As a solvent,
From the viewpoint of evaporation rate, etc., those having a boiling point of about 60 to 200°C are 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, metal powders such as iron, aluminum, cobalt, nickel, steel, ferrite, magnetite, Mn-Cu
-A1, Mn-Cu -8n etc. alloy powder: CrO
Examples include metal oxide powders such as No. 2, silica sand, and inorganic oxide powders such as glass peas.

The carrier of the present invention is used in combination with known toners. Such toners include, for example, resins such as polystyrene, styrene-acrylic acid copolymer, polyester, polyvinyl butyral, ethylene-vinyl acetate copolymer, and polyamide, and carbon black, spirit black, nigrosine, benzidine yellow, and sproine yellow. It consists of colorants such as microlith yellow, quinacridone, rhedamine, carmine, phthalocyanine blue, oil blue, alkali blue, and ultra blue, as well as charge control agents and fluidizing agents.

The carrier of the present invention and such toners are used for electrostatic image development using magnetic brush methods, cascade methods, and the like.

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, so it not only has excellent durability but also Gives carrier high chargeability.

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

Example I CTFE/Pr=53/47 (molar ratio) and molecule ff1
200,000 copolymer with ethyl acetate/methyl ethyl ketone
After preparing a coating liquid with a solid content concentration of 2% by weight by dissolving it in a mixed solvent of 1/1 (weight ratio), it was applied to still powder with a particle size of 200 μm as a carrier using a fluidized spray method according to a conventional method. A carrier having a resin film thickness of 2 It m was obtained by coating.

Example 2 CTFE/Pr/I□Lifluoroethyl vinyl ether-51/35/14 (mole ratio) The resin film thickness was changed in the same manner as in Example 1 except that a copolymer with a molecular weight of 80,000 was used. A carrier of 2 μm was obtained.

Example 3 CTFE/Pr/Hydroxybutyl vinyl ether=5
A copolymer with a molecular weight of 0/4515 (mole ratio) of 450,000 was dissolved in a mixed solvent of ethyl acetate/methyl ethyl ketone = 1/1 (weight ratio) to make a solution with a solid content concentration of 2% by weight, and then a crosslinking agent was added. Hexamethylene diisocyanate triplet (trademark: "Coronate EH", manufactured by Nippon Polyurethane Industries, Ltd.) was mixed in a proportion of 13% by weight of the resin.

Using the obtained coating liquid, a carrier having a resin film thickness of 2 μm was obtained in the same manner as in Example 1.

Regarding the carrier obtained in this example, various measurements were performed 7 days after the resin film was formed in order to sufficiently cure the resin film.

Example 4 To 60 parts by weight of a fluororesin obtained in the same manner as in Example 1, 2.
40 parts by weight of 2,3.3-tetrafluoromethyl methacrylate polymer (molecular weight 100,000) was mixed, and the following Example 1 was prepared.
A carrier having a resin film thickness of 2 μm was obtained by dissolving in a solvent and coating the core material in the same manner as described above.

Comparative Example 1 A membrane was prepared in the same manner as in Example 1, except that 2.2,3.3.4,4.5.5-octafluoropentyl methacrylate-1 polymer (molecular weight 100,000) was used. A comparison carrier having a thickness of 2 μm was obtained.

Comparative Example 2 Vinylidene fluoride/tetrafluoroethylene = 80/
20 (molar ratio) of a copolymer (molecular weight 100,000), and the solvent was acetone/methyl ethyl ketone = 1/
A comparative carrier having a film thickness of 2 μm was obtained in the same manner as in Example 1 except that the mixed solvent of Example 1 was used.

Test Example 1 The following toner chargeability test was conducted for each carrier obtained in Examples 1 to 4 and Comparative Examples 1 to 2.

100 parts by weight of styrene resin (trademark "Picolastic D125", manufactured by Shell Standard Oil Co., Ltd.), 10 parts by weight of carbon black (trademark "Regal 660R", manufactured by Cabot Corporation) and low molecular weight polypropylene (trademark "
100 parts by weight of the above carrier was mixed with 10 parts by weight of toner having an average particle diameter of 10 μm and made of a mixture of Viscol 660P'' (manufactured by Kochu Kasei Co., Ltd.), and the toner was charged f1.
(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 is charged m (Q/M
: unit μc/g) was again determined by the blow-off method.

The results are shown in Table 1.

Table 1 Example Initial value 1 after 1000 hours
+22 +162 +2
8 +213 +12
+84 +25
+12 Comparative example 1 +21 +22
+36 +5 From the results shown in Table 1, it is clear that the carrier of the present invention has excellent charging stability.

On the other hand, the carrier according to the comparative example has significantly poor charging stability. This is presumed to be due to poor adhesion.

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Claims (2)

[Claims] (1) A carrier for electrostatic charge development in which a carrier core material is coated with a copolymer comprising 30 to 70 mol% of chlorotrifluoroethylene and 70 to 30 mol% of propylene, or a composition containing the copolymer. (2) chlorotrifluoroethylene 30 to 70 mol%,
A copolymer prepared by copolymerizing 70 to 30 mol% of propylene and an unsaturated double bond-containing monomer copolymerizable with these in a proportion of 0.1 to 20% by weight based on chlorotrifluoroethylene and propylene, or the copolymer thereof. A carrier for electrostatic charge development comprising a carrier core material coated with a composition containing a polymer.