JPS6010261A - Coated carrier - Google Patents

Abstract

PURPOSE:To obtain a developer free from a fog by coating a polymer formed by graft-polymerizing a vinyl monomer or vilyidene monomer with a rubber-like basic polymer on a carrier. CONSTITUTION:A rubber-like copolymer consisting of 50-99wt% conjugate diene or acrylate, 1-50wt% a monomer having 4-500 alkylene oxide group and if necessary 0-49wt% >=1 king of copolymerizable vinyl monomer or vinylidene monomer is used as a basic polymer of a graft polymer. Monomers such as alkyl ester of acrylic acid, alkyl vinyl ether, (alkoxy) polyethylene glycol(meth) acrylate, etc. are usable as the vinyl monomer or vinylidene monomer used for graft polymn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carrier for a developer in electrophotography, and in particular to a carrier coated with a coating for preventing image fogging.

Conventionally, as an electrophotographic method, US Pat.
Various tabulation methods are described in Publication No. 748 and the like. In each of these methods, a charge is uniformly applied to the photoconductive layer, a latent image is formed by irradiating the photoconductive layer with a light image corresponding to the original, and then the latent image is transferred to a black powder. Develop with toner to make a visible image, transfer it to paper or the like as necessary, and permanently fix it by heat, pressure, etc. The toner used in the process of developing a latent image has conventionally been made by dispersing a colorant such as Carpin Black in a binder such as JIJ styrene resin and finely pulverized to about 1 to 30 μm in size. The toner is mixed with a carrier material called a carrier, usually iron powder or glass beads, and used as a developer. These carriers are mixed with what is called a toner, which is a dye or pigment dispersed in a binder resin.

Conventionally, many developers have caused toner fog in non-image areas and decreased image density after 10,000 to 30,000 copies have been made in a large number of copies. The reason for this is that in the case of copying a large number of copies, the iron powder and toner that adhere firmly in the initial state due to the Coulomb force are not transferred to the latent image, and when tens of thousands of copies are made, heat or shock from the machine etc. Due to the heat of 1:
However, since the carrier to which the toner is fused is insufficiently charged by friction with the toner, fogging occurs in the image.

The present invention provides a coated carrier for magnetic brush development which overcomes the above-mentioned drawbacks.

That is, in the coated carrier of the present invention, a conjugated diene or/
and Nisder acrylate, a monomer having an alkylene oxide group, and optionally 91 or more types of copolymerizable vinyl monomers or vinylidene monomers, and one or more types of polymers. The surface of the carrier is coated with a resin containing at least a graft copolymer obtained by graft copolymerization of vinyl monomer or vinylidene monomer. It is presumed that the phases are dispersed in a solstice state with each other in the branched polymer phase, forming a matrix phase basin, so the triboelectric charges generated on the carrier and toner surfaces are held extremely stably. . For example, when an excessive charge that is unfavorable to development occurs under low temperature, low humidity moxibustion conditions, the excess charge is selectively diffused and attenuated through the rubber frame type coalescence, and is stabilized at a certain saturation value. In addition, under high temperature and high humidity conditions, even if the rubber phase absorbs moisture, it does not affect the toner.
This also has a stabilizing effect.

The frame-shaped combination of graft polymers used in the present invention preferably has the following composition.

That is, conjugated diene or acrylic ester 50
~99ffiiL% and 1 to 50% by weight of monomer with 4 to 500 alkylene oxide groups and optionally 91
It is a rubbery copolymer consisting of 0 to 49% by weight of more than one type of copolymerizable vinyl monomer or vinylidene monomer.

As the monomer having 4 to 500 alkylene oxide groups, one or more monomers having the following formula: O2R3 or (in the formula R,, Ft2.R3 is hydrogen or an alkyl group having 1 to 4 carbon atoms, or hydrogen or an alkyl group having 1 to 9 carbon atoms, R4, R5, and R6 are hydrogen or an alkyl group having 1 to 90 carbon atoms. mln is 4≦m + n≦5°0, Me represents hydrogen rNa l'L1 or K. Y is hydrogen, an alkyl group having 1 to 40 carbon atoms, a dikb alkyl group having 3 to 6 carbon atoms, a phenyl group, or R2R3 (4≦m'+1'≦500.) Of course, it is also possible to use a similar qii compound having a polyalkylene oxide group and capable of lowering the volume electrical resistivity of the rubber backbone polymer.

Of the nine alkylene oxide groups, 4 to 50Q pieces are necessary, and it is more preferable that the number is 9 to 50 pieces.

When the number of alkylene oxide groups is less than 4, it is difficult to obtain m control properties, and when there are more than 50Q, #-j
: Polymerizes, the monomer KM is difficult to decompose in water, and the polymerizability is also poor.

Furthermore, if the amount of the monomer having a polyalkylene oxide group is less than I M % of the rubber backbone polymer, antistatic properties cannot be imparted. Moreover, if it exceeds 50% by weight, difficulties arise in polymerizability and manufacturability.

As the copolymerizable vinyl heavy body or vinylidene monomer used in the rubber backbone polymer, known monomers can be used.

For example, methacrylic acid alkyl ester, acrylic acid,
Methacrylic acid, acrylamide, methacrylamide, vinyl acetate, unsaturated nitrile, aromatic vinyl, alkyl vinyl ether, alkyl vinyl ketone, 2-hydroxyethyl (meth)acrylic acid ester, diaheptone acrylamide, vinyl chloride, vinylidene chloride, itacon I
'fa, itaconic acid alkyl ester, isobutine, 2
One or more monomers such as -acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate, etc. can be used.

In addition, the comb backbone polymer may contain an L-crosslinking agent (for example, a vinyl group, a 1,3-butadienyl group, an acrylic group,
A polyfunctional monomer having two or more of one or more of methacrylic groups and allyl groups can also be used.

The ratio of rubber trunk polymer and branch polymer is 2 to 80% by weight of the former.
, preferably 8 to 70% by weight, the latter being 20 to 95% by weight
, preferably in the range 30-92% by weight FM.

When the amount of the 2M base polymer is less than 80% by weight, it is difficult to control the charging characteristics of the toner, and when it is more than 80% by weight, the high humidity characteristics deteriorate.

As the vinyl monomer or vinylidene monomer used in graft polymerization, known monomers can be used. For example, acrylic acid alkyl ester, methacrylic acid alkyl ester, acrylic acid, methacrylic acid, acrylamide, methacrylamide, vinyl acetate, unsaturated nitrile,
aromatic vinyl, conjugated diene, alkyl vinyl ether,
Alkyl vinyl ketone, 2-hydroxyethyl (meth)
Acrylic acid ester, (alkoxy) number? One or more monomers such as lyethylene glycol (meth)acrylic acid ester, diaseptone acrylamide, vinyl chloride, vinylidene chloride, itaconic acid, itaconic acid alkyl ester, isobutyne, etc. can be used.

0.1 to 50 of these graft copolymer ore total binder resins
The weight ratio is preferably used in the range of 5 to 40%.

If, in addition to the graft polymer, another binder resin is used in the coated carrier according to the invention, all known materials can be used. In this case, it is necessary that the proportion of the graft polymer be at least 10% by weight, so that the effects of the present invention can be exhibited.

For example, polystyrene, polystyrene-butadiene copolymers, styrene-based copolymers such as styrene-acrylic copolymers, polyethylene, polyethylene-vinyl acetate copolymers,
These include ethylene copolymers such as polyethylene vinyl alcohol copolymers, phenol resins, epoxy resins, allyl phthalate resins, polyamide resins, polyester resins, maleic acid resins, and the like. Furthermore, there are no particular restrictions on the manufacturing method of any of the resins. This is because conventionally, resins produced by emulsion polymerization or the like tend to contain impurities and are difficult to use, but the present invention allows them to be easily used, and the range of resin selection is greatly expanded. This is also a great effect of the present invention.

The carrier used in the present invention includes reduced iron powder,
Iron oxide powder, nickel ferrite, etc. 10μ~100
A particle size of μ is used.

The conjugated diene or/and acrylic ester of the present invention, a monomer having an alkylene oxide group, and optionally 1
A graft copolymer obtained by graft copolymerizing one or more kinds of vinyl monomers or vinylidene monomers to a rubber backbone polymer having as a constituent element one or more kinds of copolymerizable vinyl monomers or vinylidene monomers. The carrier whose surface is coated with a resin containing at least a polymer has the following percentage.

1. Charge control is easy, so any toner can be used.

2. Excellent development durability due to high mechanical strength against rubbing.

3. Compared with uncoated carriers, coated carriers have significantly improved surface lubricity, resulting in better powder flowability.

4. Fusion to the photosensitive drum is prevented, and as a result, development durability is excellent.

The coating used in the present invention is preferably applied to the carrier iron powder at a ratio of 0.3 to 50 parts by weight per 100 M parts of the carrier iron powder. 0.
If it is less than 3, the durability will deteriorate after tens of thousands of sheets, and if it is 5
．． If it is 0 or more, the frictional electrification generated between the coated carrier and the toner tends to become weaker. For preferred use, the coating is applied at a ratio of 0.3% to 5.0% based on 100 parts by weight of the carrier powder as described above. Particularly preferably, it is preferably coated in an amount of 0.5 to 3.0 parts by weight.

Next, the method for producing a coated carrier according to the present invention involves immersing a core of carrier powder in a solution of 0.3 to 5.0 g of resin dispersed in benzene, toluene, etc. Dryer (approximately 50~7
The carrier can be coated by drying the solvent at 0℃), or by flowing iron powder etc. in a flow coater at 50 to 70℃ and scattering a pre-prepared resin dispersion onto a fluidized bed of iron powder. Examples of the present invention are shown below. Parts are parts by weight.

Synthesis Example 1 In a 101 stainless steel autoclave with stirring blade (a) 1.3 butadiene 6 parts methyl methacrylate 3 parts methoxypolyethylene glycol methacrylate (average number of ethylene oxide groups is 23) 1 part tertiary dodecyl mercaptan 0.05 Part diimpropylbenzene hydroperoxide 0.02 parts Formaldehyde sodium sulfoxylate 001 parts Sulfuric acid 1st
Iron, heptahydrate 0.0004 parts Ethylenediaminetetraacetic acid disodium salt 0.0
0.06 parts Sodium birophosphate 0.05 m Sodium dodecylbenzenesulfonate 0.1 part Deionized water 30 parts (-) An aqueous solution having the composition was adjusted to PI-17 with an aqueous sodium hydroxide solution, and the mixture was thoroughly purged with nitrogen. 40
The mixture was stirred at ℃ for 20 hours. Yield: 99cm, average particle size: 0.0
A latex of 9μ was obtained. (b) 40 parts of the above latex (10 parts for the frame type combination)
Styrene 80 parts Methacrylate 10 parts Normal dodecyl mercaptan 3.6 parts Potassium persulfate 0.072 parts Hydrogen sulfate) IJum (1,0185B dodecyl inzenesulfone Hide l-lium 0.9 parts Deionized water 270 The latex was taken out, precipitated with a sulfurized aluminum aqueous solution, and precipitated with a sodium birophosphate aqueous solution.
7, and after dehydration and washing, it was dried at 55° C. for 24 hours. A white powder graft polymer was obtained with a yield of 97%.

Synthesis Example 2 Synthesis Example 1 except that methoxypolyethylene glycol methacrylate (average number of ethylene oxide groups is 9) of Synthesis Example 1 is used instead of methoxypolyethylene glycol methacrylate (average number of ethylene oxide groups is 9)
A graft polymer was obtained in the same manner as above.

Synthesis Example 3 Same as Synthesis Example 1 except that methoxypolyethylene glycol methacrylate (average number of ethylene oxide groups is 23) of Synthesis Example 1 is used as methoxypolyethylene glycol acrylamide (average number of ethylene oxide groups is 23)'f: A graft polymer was obtained.

Example 1 Carrier iron powder (40-60μ) was flowed into a flow coater at 100°C, and the graft polymer of Synthesis Example 1 was dissolved in a toluene solution to make a 2% solution.
The graft polymer was sprinkled on flowing iron powder in a flow coater so that the coated weight of the graft polymer was 5 parts by weight and dried for about 30 minutes. After drying, it is cooled and taken out, and sieved through a 250-mesh and 400-mesh sieve.The obtained material is mixed with a styrene resin toner as a carrier iron powder, and the astringency of the toner is 10.
An image durability test was conducted on 100,000 sheets using an NP-8500 machine. The image after 100,000 copies was almost the same as the starting image, with no blemishes, and was a good image. By the way, Tribo is starting (+) 8.3 pc/E!
- After 100,000 sheets ■ 74 μC/g.

Further, when a similar test was conducted under the environmental conditions of temperature, pressure, 15° C. and humidity of 10°, the images after 100,000 sheets were almost the same as the starting image, and 49 clear images with no fog were obtained.

Even in one trial at a temperature range of 5° C. and a humidity of 85%, good images with a density of less than crystalline were stably obtained in a 100,000-sheet test.

Example 2 In Example 1, the graft copolymer of Synthesis Example 2 and bar metal were used for the graft copolymer of Synthesis Example 1, and carrier 1 was used.
01) A developer was obtained in the same manner except that the graft copolymer was coated in an amount of 1M parts based on the weight part. When this was evaluated in the same manner as in Example 1, Example 1
Similar good results were obtained.

Example 3 Real M! ↓In Example 1, the graft copolymer of Synthesis Example 3 was used as carrier 100 instead of the graft copolymer of Synthesis Example 1.
A developer was obtained in the same manner except that 1 part of ml was coated with the graft copolymer in an amount of 3M. This 'lf was evaluated in the same manner as in Example 1, and similar to Example 1, excellent results were obtained.

Reference example 1

Claims (1)

[Claims] 1. A dem backbone polymer comprising a conjugated diene or/and acrylic ester and a monomer having an alkylene oxide group as constituent elements, and one or more vinyl monomers or vinylidene monomers. A coated carrier for electrophotography, the surface of the carrier being coated with a resin containing at least a graft copolymer obtained by graft copolymerization. 2. The coated carrier according to claim 1, wherein the monomer having alkylene oxide is a compound represented by the following formula. 2R3 or (in the formula, R,, R2, R are hydrogen or an alkyl group having 1 to 4 carbon atoms, or hydrogen or an alkyl group having 1 to 9 carbon atoms, and %R4, R5, R6 are hydrogen or a carbon number 1 to 9 alkyl group. m + n is 4≦m + n≦500, Me represents hydrogen + Na * Ll or K. Y is hydrogen, an alkyl group having 1 to 40 carbon atoms, an alkyl group having 3 to 6 carbon atoms, a cycloalkyl group, a phenyl group, and (2R34≦m'tenn'≦500).