JPH0251177B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing toner used in electrophotography and printing technology, and particularly to a pressure fixable developing toner.

As a conventional electrophotographic method, U.S. Patent No. 2297691
Specification of No. 42-23910, and Tokuko Sho No. 42-23910
Many methods are known, such as those described in Japanese Patent No. 43-24748, but in general, an electrical latent image is formed by various means on a photoreceptor using a photoconductive substance, and then the latent image is The image is developed using toner, and after the toner image is transferred to a transfer material such as paper as necessary, it is fixed by heat, pressure, solvent vapor, etc. to obtain a copy. Various developing methods are also known in which an electrical latent image is visualized using toner. For example, the magnetic brush method described in U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. No. 2,618,552, and U.S. Pat. No. 2,221,776.
The powder cloud method and the fur brush development method described in the specification of the present patent application, and the Japanese Patent Application Laid-open No. 1989-1999, which was previously proposed by the applicant.
A number of developing methods are known, such as the developing method described in No. 4214 and JP-A-55-18656, and the liquid developing method.

As toners used in these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. Furthermore, it is also known to use fine developing powder to which a third substance is added for various purposes.

The developed toner image is transferred and fixed onto a transfer support such as paper, if necessary. Methods for fixing toner images include heating and melting the toner using a heater or hot roller to fuse and solidify it to the support, softening or dissolving the binder resin of the toner with an organic solvent and fixing it to the support, and applying pressure. A method of fixing toner on a support by using a method is known.

Particularly recently, research on fixing by pressurization has been actively conducted from the viewpoint of resource and energy conservation. By the way, in such electrophotographic methods that utilize fixing by pressure, most of the toner properties are restricted to the physical properties for fixing by pressure, so many other physical properties are unsatisfactory. It often stops. Under these circumstances, what researchers have always kept in mind when using electrophotography using pressure fixing is the reproducibility of copies relative to the originals to be copied. Items to check for such reproducibility include, for example, sharpness, color tone, smoothness, fine line reproducibility, and so-called fog. For example, dramatic improvements in color tone and smoothness have been made through research and development of dyes and pigments that have good dispersibility in resins that are compatible with the pressure fixing process, as well as advances in dispersion improvement technology. However, despite the investment of a lot of time and human resources into research and development to improve the stability of developability regarding density unevenness, fogging, etc., there is still a large area that still leaves room for improvement.

Polyolefins are commonly used as resins for pressure fixing toners. However, due to the nature of polyolefin alone, it is difficult to disperse dyes and pigments, and the adhesiveness is low, so the image becomes too glossy. There are problems such as insufficient fixing strength against bending. It has been attempted to incorporate the thick wax into other resins that have good developability. However, in general, wax is hardly compatible with resin, and even if it is dispersed, it causes a so-called bleed phenomenon, which adversely affects developability and durability. Specifically, wax contamination on the sleeve, toner aggregation, melting point phenomenon on the photosensitive surface, etc. are noticeable. These appear on the copied image as fog, decreased density, and uneven image density.

An object of the present invention is to provide a developing toner with good pressure fixability. Another object of the present invention is to provide a pressure-fixable developing toner with good developability.

Another object is to provide a pressure-fixable developing toner that does not cause adhesion to photosensitive surfaces, developing sleeves, etc.

Still another object is to provide a pressure-fixable developing toner with good storage stability.

Still another object is to provide a pressure-fixable developing toner with good durability and stability.

Specifically, the present invention includes 30 to 90% by weight of a styrenic monomer or a mixture of a styrene monomer and an acrylic monomer, an ethylene-acrylic derivative or an ethylene-vinyl acetate copolymer, and a wax having a functional group. Contains 100 parts by weight of a solid resin (A) with a weight average molecular weight of 60,000 or less obtained by polymerizing 10 to 70% by weight, and 5 to 100 parts by weight of low molecular weight polyethylene (B) with a weight average molecular weight of 4,000 or less. The present invention relates to a developing toner characterized by:

Component (A) has strong adhesiveness and therefore exhibits strong fixing properties against bending. On the other hand, with respect to rubbing, the image exhibits a so-called "extending" phenomenon, which is hardly satisfactory. On the other hand, component (B) has good fixing properties against rubbing but is weak against bending. That is, by containing (A) which exhibits strong fixing properties against bending and (B) which exhibits strong fixing properties against rubbing, it was possible to obtain a pressure fixing developing toner that satisfies both bending and rubbing. .

The content ratio of (A) and (B) is determined from the viewpoint of fixability and developability.
It is desirable to use 5 to 100 parts by weight (preferably 7 to 80 parts by weight) of (B) per 100 parts by weight of (A). If component (B) is less than 5 parts by weight, the bending fixing property is good but the sliding fixing property is weak, and if it is more than 100 parts by weight, the bending fixing property is poor.

It is quite difficult to incorporate wax into the resin even when using ordinary mixing equipment, and it is not possible to obtain a mixture in a satisfactory state even if kneading is performed for a long time using commonly used melt-kneading equipment.

The inventors of the present invention considered obtaining a uniform dispersion system by mixing the wax in a resin monomer and then polymerizing it, but although a particularly good dispersion system was actually obtained, it was not practical. It is still unsatisfactory. This is because although the wax component is extremely well dispersed in the collection of polymer chains, there is no interaction between the polymer chains and the low molecular weight wax component, which can be obtained using a normal mixing device. This seems to be because, although it is better than the mixed mixture, a bleed phenomenon eventually occurs as time passes.

In view of this, the inventors conducted many experiments by changing waxes and monomer types, and found that
It has been found that waxes require appropriate functional groups. For example, a dramatic improvement in developability has been achieved by mixing waxes containing hydroxyl groups, glycidyl groups, carboxyl groups, etc. in monomers and carrying out polymerization as described above. This is thought to be because the functional group has some form of mutuality with the polymer chain, but the details are unknown. During this polymerization, if an ethylene acrylic derivative or an ethylene vinyl acetate copolymer is included, the effect on developability will be even better. This is thought to be because the dispersion of the wax into the styrene monomer polymerization liquid is greatly promoted by the ethylene acrylic derivative or the ethylene vinyl acetate copolymer. It is thought that these substances probably have a surfactant effect.

Examples of ethylene acrylic derivatives include ethylene ethyl acrylate.

The amount of ethylene acrylic derivative or ethylene vinyl acetate copolymer in the mixture of wax and monomer should not exceed the amount of wax used. This is because these ethylene acrylic derivatives generally have a low glass transition point and deteriorate high-temperature storage stability.

The styrene monomer or styrene-acrylic comonomer constituting the resin (A) tends to make good developability more noticeable.

Examples of styrenic monomers include styrene,
There are styrene derivatives such as α-methylstyrene and p-crossstyrene.

Styrene-acrylic comonomer is a comonomer of these styrene monomers and acrylic monomers. Acrylic monomers include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, and acrylic monomer. phenyl acid, methacrylic acid, methyl methacrylate, ethyl methacrylate,
Examples include butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, and acrylamide.

As long as the wax used in the present invention has a carbon number of 10 or more and a number average molecular weight of 10,000 or less, it can be used satisfactorily as long as it has an appropriate functional group. For example, saturated straight chain fatty acids such as stearic acid, montanic acid, n-hexatetracontanoic acid, esters thereof, and derivatives thereof;
For example, monounsaturated fatty acids such as lindelic acid, oleic acid, and ceracoleic acid, their ester numbers, and their derivatives; for example, saturated alcohols such as behenyl alcohol, ceryl alcohol, and mericyl alcohol, their esters, and their derivatives; glycerin, etc. Polyhydric alcohols and their esters and derivatives thereof; For example, saturated fatty acid amides and their derivatives such as behenic acid amide and palmitic acid amide; For example, unsaturated fatty acid amides such as erucic acid amide, braidic acid amide, and elaidic acid amide; Derivatives thereof; For example, bis fatty acid amides such as methylene bisbehenic acid amide and ethylene bis stearic acid amide, and derivatives thereof; For example, N-(2-hydroxyethyl) lauric acid amide, N-(2-hydroxyethyl) stearic acid amide , N-(2-hydroxymethyl)
Monoalkylolamides such as stearic acid amide and derivatives thereof; halides of metal soaps and paraffin waxes, etc. can be used. In addition to these, amines, imines, thiols, sulfinic acids, ketenes, isocyanates, isothiocyanates, carbodiimides, ketene imines, α, β-
Waxes containing functional groups such as unsaturated carbonyl, acetylene, nitrile, epoxy, ethyleneimine, lactone, enol lactone, azlactone, isomaleimide, iminodioxolane, etc. and acid anhydride can also achieve almost the same effect. Can be done.

The amount of wax relative to the styrene monomer or styrene-acrylic comonomer depends on the presence of other monomer species, but if the amount exceeds twice the amount by weight, the properties of the wax, such as cohesiveness and poor fluidity as a toner, will become noticeable. Undesirable. Furthermore, in order to achieve this effect, at least 10% by weight of wax (preferably 15% by weight or more) is required based on the total amount of the mixture with the monomer, and in order to avoid the overt ratio of properties as wax, 70% by weight or more of wax is required. % by weight should be avoided. In this study, the best results were obtained at 15-65% by weight.

As for the low molecular weight polyethylene (B), any of high density, medium density and low density polyethylene can be used as long as it has a weight average molecular weight of 4000 or less.

The toner of the present invention can also be used as a magnetic toner. The magnetic fine particles contained in the toner may be any material that exhibits magnetism or can be magnetized, such as metals such as iron, manganese, nickel, cobalt, and chromium, magnetite, hematite, various ferrites, manganese alloys, and other ferromagnetic materials. There are alloys, etc., and fine powders of these with an average particle size of about 0.01 to 5 μm (more preferably 0.05 to 2 μm) can be used. The amount of magnetic fine particles contained in the toner is 10 to 80% by weight (more preferably 25 to 80% by weight) of the total weight of the toner.
70% by weight) is good.

Further, various substances can be added to the toner used in the present invention for the purpose of coloring, controlling charge, etc. Examples include carbon black, iron black, graphite, nigrosine, metal complexes of monoazo dyes, ultramarine blue, phthalocyanine blue, Hansa yellow, benzidine yellow, quinacridone, and various lake pigments.

Alternatively, the toner may contain 10 to 40% by weight of hydrophobic colloidal silica or the like as a fluidity improver. Of course, this fluidity improver may be mixed outside the toner and used in an amount of 0.1 to 50% by weight (based on the weight of the toner).

The present invention will be specifically explained below with reference to Examples.

Example 1 While stirring 2 kg of a xylene solution consisting of 100 g of styrene monomer and 40 g of ethylene ethyl acrylate (6169 manufactured by Nippon Unicar) at 60°C, 60 g of 12-hydroxystearic acid glyceride was added, and polymerization was carried out using benzoyl peroxide as an initiator. A solid resin was obtained. The weight average molecular weight of the resin is
It was between 20,000 and 30,000.

A toner consisting of 80 parts by weight of this resin, 20 parts by weight of low molecular weight polyethylene (Hiwax 200P manufactured by Mitsui Petrochemical Industries, Ltd., weight average molecular weight 2000) and 50 parts by weight of magnetite (EPT-500 manufactured by Toda Industries) was prepared by a conventional method. A developer containing 1.2% by weight of hydrophobic colloidal silica relative to the toner is applied to a developing device consisting of a non-magnetic sleeve with a magnet inside to develop the electrostatic latent image on the photoconductive material, and then corona When the image was transferred onto plain paper using charging, a good image was obtained that was clear and free from fog.
This image remained unchanged even after continuous copying of 10,000 sheets. Regarding the fixing properties, the copy did not peel off even when the copy was folded after passing through two metal rolls with a linear pressure of 20 kg/cm. Furthermore, the rubbing fixability was tested according to the color fastness test method (JIS-L0849) and was good at grade 4 to 5. Furthermore, a one-week long-term storage test was conducted in an atmosphere at 45°C, but no change was found in the performance as a toner.

Example 2 In Example 1, a solid resin (weight average molecular weight
28000). In addition, as a low molecular weight polyethylene, Mitsui Petrochemical Industries' 405MP (weight average molecular weight
4000) was carried out in the same manner as in Example 1, and the same results as in Example 1 were obtained.

Example 3 In Example 1, a solid resin (weight average molecular weight 24,000) was obtained using palmitic acid amide (Nitto Kagaku Amide P) instead of 12-hydroxystearic acid glyceride. Further, the same procedure as in Example 1 was performed except that 4202E manufactured by Mitsui Petrochemical Industries (weight average molecular weight: 2400) was used as the low molecular weight polyethylene, and the same results as in Example 1 were obtained.

Example 4 Styrene-isobutyl methacrylate comonomer (molar ratio 3:2) instead of styrene monomer
Solid resin (weight average molecular weight 24000) using 100g
The same results as in Example 1 were obtained when the same procedure as in Example 1 was carried out except that .

Example 5 Styrene-n-butyl methacrylate comonomer (molar ratio 5:3) instead of styrene monomer
Solid resin (weight average molecular weight 30000) using 100g
The same results as in Example 1 were obtained when the same procedure as in Example 1 was carried out except that .

Example 6 Divinylbenzene 10 was added to the monomer mixture of Example.
Example 1 was carried out in the same manner as in Example 1, except that a solid resin (weight average molecular weight 35,000) was prepared by adding g and carrying out a crosslinking reaction, and the image did not change even after continuous copying of 20,000 sheets.

Comparative example: 100g of polystyrene resin with a weight average molecular weight of 30,000
and 60 g of 12-hydroxystearic acid glyceride were melt-kneaded to obtain a kneaded product, and 80 parts by weight of the obtained kneaded product, 20 parts by weight of low molecular weight polyethylene (Mitsui Petrochemical Industries Hiwax 200P, weight average molecular weight 2000), and 50 parts by weight of magnetite. Toners were prepared using parts by weight. A developer was prepared in the same manner as in Example 1 by mixing the obtained toner and hydrophobic colloidal silica. The obtained developer had clearly inferior fluidity compared to the developer of Example 1. Also, 5
When a long-term storage test was carried out for one week in an atmosphere at ℃, a bleed phenomenon was observed in the toner, and the developer agglomerated.

Using the obtained developer, an image reproduction test was carried out in the same manner as in Example 1, and the obtained toner image was fixed in the same manner as in Example 1 using a metal roll. When the fixed image was folded, the toner image peeled off at the folded portion.

Claims (1)

[Scope of Claims] 1. 30 to 90% by weight of a styrene monomer or a mixture of a styrene monomer and an acrylic monomer, an ethylene-acrylic derivative or an ethylene-vinyl acetate copolymer, and a wax having a functional group of 10 to 90% by weight. 70% by weight of solid resin (A) with a weight average molecular weight of 60,000 or less, and 5 to 100 parts by weight of low molecular weight polyethylene (B) with a weight average molecular weight of 4,000 or less. Toner for development.