JPS63316064A - Resin coated carrier for developing electrostatic latent image - Google Patents

Abstract

PURPOSE:To impart adequate negative electrostatic chargeability to a toner and to enable the induction of a desired electrostatic charge quantity in the toner over a long period of time by specifying the copolymn. ratio of the vinyl polymerizable monomer and dialkylaminoalkyl (meth)acrylate of a copolymer and providing a coating film consisting of the copolymer of a specific quaternary ammonium salt to the toner. CONSTITUTION:This toner has the coating film consisting of the copolymer which is the copolymer of the vinyl polymerizable monomer and the quaternary ammonium salt of the dialkylaminoalkyl (meth)acrylate and in which the copolymn. ratio (wt.%) of the vinyl polymerizable monomer and dial kylaminoalkyl (meth)acrylate of the copolymer is 80-98:2-20 and the quater nary salt of the dialkylaminoalkyl (meth)acrylate is made into the quaternary ammonium salt by 0.8-1.0mol. sulfonic acid group-contg. compd. with respect to 1.0mol. dialkylaminoalkyl (meth)acrylate. The adequate negative electrostatic chargeability having excellent stability with lapse of time is thereby imparted even to the toner which is not particularly added with an electric charge control agent.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a negative image that can be used when converting an electrostatic latent image in electrophotography or electrostatic recording into a visible image by dry development. The present invention relates to resin-coated carriers for chargeable flexible toners.

[Prior Art] An overview of electrophotography or electrostatic recording (hereinafter referred to as "electrophotography") is that electrostatic charge latent is formed on the surface of a photoconductive insulating layer (hereinafter referred to as "photoreceptor"). The image is developed using colored fine powder with a positive or negative charge (hereinafter referred to as "toner"), transferred onto a support such as paper using a bias electrode, and then heated, pressurized, or with solvent vapor. A fixed image is formed by a fixing process such as.

The developing methods in the above electrophotographic method include a magnetic brush method using a developer consisting of toner and carrier;
Two-component developing methods such as the cascade method and fur brush method, and one-component developing methods using only toner such as the powder cloud method, contact developing method, jumping developing method, and magnet-dry method. The most important point in these various developing methods is that in order to more accurately visualize the electrostatic latent image formed on the photoreceptor due to positive or negative charges, electrostatic charges are applied to the toner surface. The purpose of this method is to induce and maintain a desired gap of opposite charges corresponding to a latent image, and to stably transport toner.

As a means of inducing a desired amount of charge on the toner surface, a triboelectric charging phenomenon caused by friction between the toner and a carrier, a sleeve, a doctor blade, etc. is generally applied, and this desired amount of charge is generally treated as the amount of charge. Research and development is being carried out to improve the rise of the charge amount, the stability of the charge amount over time, and the maintenance of a constant charge amount unaffected by environmental changes, etc., for toners, carriers, sleeves, doctor blades, etc. It continues.

In order to induce and stably maintain a constant charge in the toner, additives called pigments, dyes, and charge control agents are generally added to the binder when making the toner. Examples of additives that positively charge nigrosine include azine dyes containing an alkyl group having 2 to 16 carbon atoms, basic dyes, lake pigments of basic dyes, quaternary ammonium salts, organic tin compounds, and higher fatty acids. Metal salts, glass, mica, inorganic fine powder such as zinc oxide, metal complexes such as EDTA and acetylacetone, polyamine resins such as vinyl polymers containing amino groups, condensation polymers containing amino groups, etc., singly or in combination. Additives that are used in combination to negatively charge the toner include monoazo dye metal salts, nitrofumic acid and its metal salts, salicylic acid, naphthoic acid, metal complexes of dicarboxylic acids such as Co5Cr5Fe, and sulfonated copper phthalocyanine pigments. , styrene oligomers into which nitro groups or halogen groups have been introduced, chlorinated paraffins, melamine resins, etc. are used.

On the other hand, in the case of a two-component system, the object to be rubbed by these toners is an inorganic powder called a carrier, such as iron powder,
Inorganic powders such as iron oxide powder, ferrite, glass, silica sand, and aluminum are used, and in the case of -component systems, friction objects such as sleeves and doctor blades are used.

[Problems to be Solved by the Invention] In controlling the amount of charge using the above-mentioned additives, these additives have poor affinity or compatibility with the binder, so friction between the toners and collision with the carrier may occur. When subjected to impact such as friction with the toner, sleeve, doctor blade, etc., the additives present on the surface layer of the toner are released, causing the carrier, sleeve,
This contaminates doctor blades, photosensitive drums, etc. and deteriorates the toner's charging characteristics, making it difficult to reproduce high image quality over a long period of time, which is a practical problem. In addition, these additives generally have a problem that they are not suitable for use in toners for full-color copying because they are often blackish.

Regarding carriers, iron powder-based carriers are manufactured by the ore reduction method, atomization method, mill scale method, nitriding crushing method, iron powder melting method, etc., but the iron powder obtained by these manufacturing methods is Because of its low electrical resistance, its surface is oxidized and used as a carrier. however,
It is thought that a certain part of the carrier surface is a high-resistance Fe2O3 layer, and another part is a Fe3O4 layer, and there is a limit to increasing the resistance of the iron powder carrier.

In addition, the ferrite carrier is Fe2O3, N to,
cuoScoo, MgO, ZnO.

The main raw materials are MnC0BaCO3, SrCO3, etc., and additives and L/TA I 203, B! 203, V20
5, Pt) O, 5n02, T! 02, CaCO3,
S! Mixed with 02 etc., pre-calcined, finely pulverized, granulated, molded,
It is generally produced by a dry method consisting of a high-temperature firing process, but the electromagnetic properties, electrical resistance,
It has the disadvantage that extremely sophisticated manufacturing technology is required to control the magnetic properties, etc., and the cost is high. In addition, glass beads carriers are chemically stable, easy to mold, and have good miscibility with toner, charging properties, and fluidity, but when used for long periods of time, they may break due to various impacts and surface scratches may occur. This results in problems with its stability as a carrier.

Furthermore, even if these various carriers are used, it is currently difficult to induce the desired amount of charge in the toner, and it is difficult to induce the desired amount of charge in the toner. is common.

In addition, for the purpose of increasing the resistance value of the carrier, imparting long-term stability, and inducing a high charge amount to the toner, various synthetic resins such as fluorine resin, acrylic resin, styrene-acrylic copolymer resin, silicone resin are added to the surface of the carrier. , polyester resin, polybutadiene resin, etc., or alternatively, a method of coating with a mixture of these resins and an additive such as a charge control agent has been studied and implemented. however,
These methods also have problems such as slow initial rise rate of charge, additives detaching from the coating, and inability to maintain stable charge during long-term use.

The present invention aims to solve the above-mentioned problems, that is, to provide a resin-coated carrier that can impart appropriate negative chargeability to toner and induce a desired amount of charge in the toner over a long period of time. The aim is to create a resin coating that can reduce the amount of charge control agent mixed in the binder or induce an appropriate amount of negative charge even on unused toner. The second purpose is to provide a carrier.

[Means for Solving the Problems] That is, the present invention provides a copolymer of a vinyl polymerizable monomer and a quaternary ammonium salt of dialkylaminoalkyl (meth)acrylate, wherein the vinyl polymerizable monomer of the copolymer is and dialkylaminoalkyl (meth)acrylate (wt%) is 80 to 98:2 to 20, and the quaternary salt of dialkylaminoalkyl (meth)acrylate is dialkylaminoalkyl (meth)acrylate 1 0.0 mole of sulfonic acid group-containing compound.
An electrostatic latent image characterized by having a coating film of a copolymer (hereinafter referred to as "quaternary ammonium salt copolymer") that is a quaternary ammonium salt in an amount of 8 to 1.0 mol. The above object has been achieved by providing a resin-coated carrier for development.

In the present invention, the quaternary ammonium salt copolymer comprises a vinyl polymerizable monomer and a dialkylaminoalkyl (
meth)acrylate is made into a copolymer, and then made into a quaternary ammonium salt with an organic compound having a sulfonic acid group (herein sometimes referred to as a "sulfonic acid group-containing compound"), or a vinyl A copolymer is formed by a polymerizable monomer and a monomer in which dialkylaminoalkyl (meth)acrylate is made into a quaternary ammonium salt with an alkyl halide, and then a compound having a sulfonic acid group is added to perform a dehalogenation aqueous reaction. In can be done.

Examples of vinyl polymerizable monomers that can be used to produce the quaternary ammonium salt copolymer of the present invention include styrene, α-methylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate. ) acrylate, n-butyl (meth)acrylate, 1sO-butyl methacrylate, cyclohexyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylic acid, vinyl acetate, vinyl propionate, and the like.

Examples of dialkylaminoalkyl (meth)acrylates that can be used in the present invention include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate.
di(lower alkyl)aminoethyl (meth)acrylate such as meth)acrylate and dibutylaminoethyl (meth)acrylate.

Examples of organic compounds having a sulfonic acid group that can be used when making a copolymer of a vinyl polymerizable monomer and a dialkylamine ethyl (meth)acrylate into a quaternary ammonium salt include para-toluenesulfonic acid alkyl ester, e.g. , methyl paratoluenesulfonate,
Ethyl para-toluenesulfonate and propyl para-toluenesulfonate are preferred.

In addition, examples of the alkyl halide that can be used when converting dialkylaminoalkyl (meth)acrylate into a quaternary ammonium salt with an alkyl halide include methyl chloride, methyl bromide, ethyl chloride, ethyl bromide, and propyl chloride. , propyl bromide, butyl chloride, butyl bromide, etc.

Sulfonic acid group-containing compounds that can be used to produce the quaternary ammonium salt copolymer of the present invention include methyl sulfonate, ethyl sulfonate, propyl sulfonate,
Para-toluenesulfonic acid and naphthalenesulfonic acid are preferred.

The quaternary ammonium salt copolymer that can be used to obtain the resin-coated carrier of the present invention can be obtained by copolymerizing the above-mentioned components according to a conventional method. Vinyl polymerizable seven-layer inside
The copolymerization ratio of is in the range of 80 to 98% by weight, especially 87% by weight.
The range is preferably 97% by weight. That is,
If the copolymerization ratio is more than 98% by weight, the ability to induce negative charge on the toner will be poor, and if it is less than 80% by weight, the quaternary ammonium base concentration in the copolymer will be relatively low. This is undesirable because it causes an increase in resistance, a decrease in resistance value, and a decrease in film properties when coated on a carrier.

In addition, the copolymerization ratio of dialkylaminoalkyl (meth)acrylate or quaternary ammonium salt monomer of dialkylaminoalkyl (meth)acrylate used as a copolymerization component of vinyl monomerizable hexamer is 2 to 20% by weight. It is preferably 3 to 13%.

The organic compound having a sulfonic acid group is 0.8 to 1 mol per 1.0 mol of dialkylaminoalkyl (meth)acrylate or its quaternary ammonium salt monomer.
．． It is used in a range of 0 mol, preferably in a range of 0.85 to 1.0 mol. 0 organic compounds with sulfonic acid groups
．． Less than 8 moles induces the necessary negative charge on the toner.

On the other hand, if the amount exceeds 1.0 mol, organic compounds with unreacted sulfonic acid groups will remain in the coating film, causing toner contamination. It does not have any positive effect on charge induction.

In the copolymerization of the above vinyl polymerizable hexamer with dialkylaminoalkyl (meth)acrylate or quaternary ammonium salt of dialkylaminoalkyl (meth)acrylate, organic peroxide-based or azo-based polymerization is used as a polymerization initiator. Although initiators can be used, organic peroxides are not preferred because their decomposition products have carboxyl groups, and azo initiators such as azobisisobutyronitrile, azobisdimethylvaleronitrile, azobis( 2,4-dimethyl-4-methoxyvaleronitrile), 2-phenylazo (2,4-dimethyl-4-methoxyvaleronitrile), etc. to the seven-mer mixture
It is preferable to use it in a range of 5% by weight. In addition, any method such as solution polymerization, suspension polymerization, or bulk polymerization can be used as the polymerization method, and is not particularly limited. “
It is particularly preferable to employ a solution polymerization method in which the above-mentioned heptamer mixture is copolymerized in a conventional solvent because it is easy to control the MW".

In the present invention, the MW of the quaternary ammonium salt copolymer
is not particularly limited, but is preferably 3°000 or more; if MWh is less than 3,000, the charging property will be greatly reduced in a high humidity environment and the strength of the coating will be reduced. It becomes less stable as a carrier.

The resin-coated carrier of the present invention uses an organic solvent that is a good solvent for the quaternary ammonium salt copolymer, such as aromatics such as benzene, toluene, and xylene, acetone, methyl ethyl ketone, and isobutyl ketone. After dissolving it in a mixed solvent such as ketones, acetate esters such as ethyl acetate, propyl acetate, and butyl acetate, and alcohols such as methanol, ethanol, propatool, and butanol to form a coating liquid, apply it to the carrier surface. It can be manufactured by

The coating liquid may contain other resins as necessary, such as polystyrene, polyacrylic ester, polymethacrylic ester, polyacrylonitrile, synthetic rubber resin, polyurethane, polyamide, epoxy resin, polycarbonate, phenol resin, polyethylene. It is also possible to contain resins such as , polypropylene, and silicone resins, and in addition, silica powder, aluminum oxide, cerium oxide, silicon carbide, carbon black, oxide, etc., which are conductivity imparting agents to improve the carrier properties. For example, fatty acid metal salts, vinylidene fluoride, etc. may be mixed with tin to adjust conductivity, and with the purpose of preventing spent toner deposition.

Examples of carriers capable of coating the above-mentioned quaternary ammonium salt copolymer include iron powder, iron oxide powder, ferrite, magnetic metal powder such as nickel, glass beads, silica particles, sodium chloride, ammonium chloride, and Rochelle salt. The particle size is preferably about 20 to 1000 μm, preferably about 30 to 300 μm.

To illustrate the method for producing the resin-coated carrier of the present invention, carrier particles are suspended in an atmosphere at about 50 to 60°C,
The quaternary ammonium salt copolymer may be spray-dried as a dilute solution containing 1 to 10% by weight, or alternatively, the quaternary ammonium salt copolymer may be spray-dried as a dilute solution containing 1 to 10% by weight, or alternatively, in a dilute solution of the polymer, 0.1 to 100@4 parts of a dilute solution of 8 About 10 parts by weight of carrier particles are added, thoroughly dispersed using a ball mill, high-speed stirrer, etc., and then spray-dried.

It is also possible to apply the above-mentioned quaternary ammonium salt copolymer to the surface of a sleeve, doctor blade, etc. in a one-component development method to impart properties equivalent to those of the resin-coated carrier of the present invention.

[Example] Hereinafter, the present invention will be briefly and specifically described based on Examples. Incidentally, the copolymerization ratio or mixing ratio of each component in the examples is expressed on a weight basis unless otherwise specified.

Example-1 2 equipped with a stirrer, condenser, thermometer, and nitrogen inlet tube
, 1! In a flask, 300g of methanol, 10g of toluene
0 g, styrene 540 g, dimethylamine ethyl methacrylate 60 g and azobisdimethylvaleronitrile 8 g were charged, and solution polymerization was carried out at 70° C. for 12 hours with stirring and nitrogen introduction. Add 100 g of methanol and 71.0 g of methyl p-toluenesulfonate, and perform salt formation while stirring at 70'C for 5 hours to obtain quaternary ammonium salt copolymer (I).
It's 19.

In a solution of the above polymer (I>100g) in a mixed solvent of 400q of toluene, 400!7 of methyl ethyl ketone, and 2009 of methanol, 1Nf of iron powder with a particle size of about 200 μm was added.
After stirring and mixing in a ball mill for about 60 minutes, the mixture was dried in a spray dryer, and a resin-coated carrier was prepared using a 55-mesh sieve.

Styrene/n-BMA (65/35) copolymer (Mw
320,000) and 5 parts of carbon black (U-Ben 3500 manufactured by Cabot Corporation) were kneaded, pulverized, and classified to obtain a particle size of 5 to 20 t1m.

The toner had an average particle diameter of 10.8 μm.

For 100g of the above carrier, 10g of the above toner
When the amount of charge of this developer was measured by a blow-off method, it was -18.7 μG/'J.

Further, this developer was subjected to a continuous durability test of 10,000 copies using a Sharp Co., Ltd. 5F825 copying machine, and there were no problems with the image characteristics (gradation, reproducibility, fog, etc.) of the copied images. In addition, when we measured the amount of charge on the residual toner in the toner box after each 1°,000 copies were made in the same manner as above, it was -18.2 ± 0.5 μG/9.
It had excellent stability.

Example-2 Styrene/n-BMA (65/35, MW32o, o
A toner was prepared in the same manner as in Example 1 with the following composition: 100 parts of copolymer, 5 parts of carbon black (Mitsubishi Carbon M-100, 0.7 parts of Bontron 5-34 (Orient Chemical Co., Ltd. 1)). , 3 parts of this toner and 97 parts of the carrier of Example-1 were mixed to prepare a developer.

Regarding the developer obtained above, the charge amount was measured in the same manner as in Example-1, and it was found to be -22.7 μc/li. In addition, this developer 100y was added to polyethylene 10
When placed in a 0d container and rotated at 60 rpm, changes in the amount of charge were measured in 100 hour units up to 2000 hours.
The amount of charge was stable at -22.3±0.6 μG/'F.

Example-3 Into a reaction vessel similar to Example-1, 300 g of methanol, 1009 toluene, 570 g of styrene, 30 g of methyl chloride quaternary salt of dimethylamine ethyl methacrylate, and 8 g of azobisdimethylvaleronitrile were charged.
! After solution polymerization for 12 hours at 65°C under nitrogen introduction, the resulting solution polymer was cooled, and roughly mixed with 150 g of toluene,
Methanol 1009, para-toluene sulfone! 24.8
9 and stirred at 50°C for 4 hours to form a salt.
grade ammonium salt copolymer polymer (II) (MW5.7
00> was obtained.

This polymer (II>159 and polymethyl methacrylate (Mw450,000>35g) were dissolved in 350g of toluene, 500g of methyl ethyl ketone, and 150g of ethyl acetate, and the particles were suspended in an atmosphere at 50°C with a particle size of approximately 200μ.
A resin-coated carrier was obtained by spraying onto m of iron powder and drying.

98 parts of this carrier and 2 parts of the toner of Example-2 were mixed to prepare a developer, and the charge amount was measured in the same manner as in Example-1, and it was found to be -19.5 μG/'J.

Further, when an electrostatic latent image on a selenium photoreceptor was developed by a cascade development method using this developer, a good image was obtained.

Example-4 Into a reaction vessel similar to Example-1, 582 g of styrene, 189 g of diethylaminoethyl methacrylate, 5 g of polymerization initiator, and 105 g of methyl ethyl ketone were charged.
After reaction at 0'C for 12 hours, methyl ethyl ketone 2959
R and 15.41j of methyl p-toluenesulfonate were added and reacted at 80°C for 5 hours to obtain a quaternary ammonium salt copolymer (III).

This polymer (I[I) was dissolved in a mixed solvent of toluene/methyl ethyl ketone (1/1) to make a 4% solution.
A resin-coated carrier was obtained in the same manner as in Example 1.

The amount of charge of the developer consisting of 100 g of this carrier and 10 g of the toner of Example-1 was -20.2 μC/cJ. Further, the developer band 1ffi consisting of this carrier 1009 and 3 cJ of toner of Example-2 is -23.7 μC/
9, and the charge amount change similar to Example-2 is -24.0
It was stable at ±0.5μC/SF.

[Effects of the Invention] Although the resin-coated carrier for electrostatic latent image development of the present invention merely coats all kinds of conventionally commonly used carriers with a copolymer of a specific composition, First, it is an extremely excellent product that can impart negative chargeability to toner, especially toner to which no charge control agent is added, which is appropriate and has excellent stability over time.

Claims (1)

[Claims] A copolymer of a vinyl polymerizable monomer and a quaternary ammonium salt of dialkylaminoalkyl (meth)acrylate, the copolymerization ratio (wt%) of the vinyl polymerizable monomer and dialkylaminoalkyl (meth)acrylate in the copolymer. ) is 80-98:2-20, and the quaternary salt of dialkylaminoalkyl (meth)acrylate is 0.8-1% of the sulfonic acid group-containing compound per 1.0 mol of dialkylaminoalkyl (meth)acrylate. A resin-coated carrier for developing electrostatic latent images, characterized in that it has a coating film of a copolymer which is a quaternary ammonium salt by .0 mol.