JPH07209901A - Photodegradable electrophotographic toner - Google Patents

Abstract

(57) [Abstract] [Purpose] By using the toner of the present invention as a toner for electrophotography, it is possible to remove the printed portion only by mechanically rubbing it after irradiating the printed matter with ultraviolet rays. , To allow the reuse of paper. [Structure] In an electrophotographic toner containing a resin, a colorant, a charge control agent, and an offset preventive agent, the resin is
Photodecomposition characterized in that it is a copolymer in which at least one of its constituent monomers is phenyl isopropenyl ketone, and at least one of the colorants is an organic colorant selected from phthalocyanine type and benzidine type. Electrophotographic toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, and more particularly to a photodegradable electrophotographic toner. More specifically, the present invention relates to an electrophotographic toner suitable for recycling paper.

[0002]

2. Description of the Related Art In recent years, various output devices such as copiers, laser beam printers, and facsimiles have been widely used in order to increase and transmit information. It is true that social activities cannot be promoted efficiently and smoothly without the existence of these devices, but on the other hand, with the increase in the amount of paper used due to the increased frequency of use of these devices, destruction of forest resources,
It is also true that the problem of garbage in cities has become a major social problem. In order to solve these problems, the concept of paperless using storage media such as magnetic tape, floppy disk, and optical disk is being introduced, but it is generally confirmed by printed paper as before. , Paper usage is still increasing.

As for the problem of garbage in the city, the local government has promoted the separate collection of paper for the purpose of recycling the paper, and although it has some effect, it is still not sufficient. On the other hand, among the above output devices, electrophotographic output devices are preferably used because of their printing quality, printing speed, color compatibility, and degree of freedom with respect to the type of paper, and it is estimated that the number will continue to increase. One of the attempts to solve the above-mentioned problems in these electrophotographic systems is a so-called decoloring toner disclosed in Japanese Patent Laid-Open No. 5-134448. The printed matter can be erased by irradiating the printed matter by a copying machine using this toner with light of a specific wavelength. As a result, the erased paper can be reused and the paper resources can be saved.

However, the electrophotographic developer using the decolorizable toner has some problems due to the electrophotography as described below. Although there are several electrophotographic methods, the method in which the decoloring toner is preferably used is a so-called two-component developer method. This is a method using a so-called two-component developer which is a mixture of carrier particles such as glass beads and iron powder and toner particles containing a resin, a coloring material, a charge control agent, an offset preventing agent and the like as a main component. In this two-component developer, minute toner particles are held on the surface of relatively large carrier particles by the electric force generated by the friction between the two particles, and an electrostatic latent image is formed when the electrostatic latent image is approached. The attraction force of the electric field to the toner particles in the latent image direction overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and attached on the electrostatic latent image to visualize the electrostatic latent image. is there. Then, the developer is repeatedly used while replenishing the toner consumed by the development. Therefore, the carrier must always triboelectrically charge the toner particles to a desired polarity and to a sufficient amount of charge during long-term use. However, the developer using this decolorizable toner has a high humidity due to the hydrophilicity derived from the quaternary ammonium salt, as can be easily imagined from the chemical structural formula of the decolorizable colorant in the decolorizable toner. The triboelectrification property under the environment is not stable. In other words, rain
In a high humidity environment such as heaven, stable copies cannot be obtained. Although the printed matter with the decoloring toner is apparently white paper, the decoloring toner is present there, so copying with such paper will contaminate the surface of the photoconductor in the copying machine. As a result, the electrical characteristics of the photoconductor are deteriorated, and as a result, it is impossible to stably obtain a high quality copy.

Further, in the case of using decolorizing toner,
It is difficult to obtain a color toner of any color, and there is a limit to the future market trend in which a color copy having good color reproducibility is required.

[0006]

The present inventors have accomplished the present invention as a result of earnestly examining the application of a photodegradable resin to an electrophotographic toner. The present inventors have been investigating a black toner for electrophotography by dispersing carbon black or the like in the photodecomposable resin used in the present invention. It was found that the photocatalyst does not give sufficient photodegradability because the proportion absorbed by carbon black becomes large, and as a result of intensive studies on the effect of the colorant on the photodegradable resin, the present invention has been achieved.

The first object to be solved by the present invention is to
By using the toner of the present invention as the electrophotographic toner, it is possible to remove the printed portion only by mechanically blowing compressed air, bending, refracting or rubbing after irradiating the printed matter with ultraviolet rays. , Allows the reuse of paper. A second object to be solved by the present invention is to provide an economical and high quality two-component developer capable of obtaining a stable image even when it is used for a long time in a high humidity environment. A third object to be solved by the present invention is to provide an economical and high quality two-component developer capable of obtaining a stable image even when used for a long time without contaminating the surface of the photoreceptor. Is.

A fourth object to be solved by the present invention is to
It is an object of the present invention to provide a color toner having good color reproducibility that can cope with colorization.

[0009]

The present invention provides a resin, a colorant, and
In an electrophotographic toner containing a charge control agent and an anti-offset agent, the resin is a copolymer in which at least one of the constituent monomers is phenyl isopropenyl ketone, and at least one of the colorants is phthalocyanine. A photodegradable electrophotographic toner, characterized in that it is an organic colorant selected from the group consisting of a type and a benzidine type. The photodegradable electrophotographic toner that can be preferably used in the present invention can be achieved by using a photodegradable resin as the resin. The photodegradable resin is a copolymer having phenyl isopropenyl ketone as one of the constituent monomers, and can be easily obtained by those skilled in the art by the method described below.

The copolymer used in the present invention is described in the literature [K. SUGITA et al. JOURNAL OF POLYME] published by the present inventors.
R SCIENCE Polymer Chemistry Edition 14 1901 -1913
(1976) and K.SUGITA et al Polymer Journal, Vol.25,
No.10.1059 -1067 (1993)], the amino compound obtained by the Mannich reaction of substituted and unsubstituted bromoiophenone is deaminated to give a substituted and unsubstituted phenylisotope. It can be obtained by obtaining propenyl ketone and then copolymerizing a monomer such as styrene and acrylate in the presence of a polymerization initiator.

The phenyl group of the phenyl isopropenyl ketone used in the present invention is a substituted or unsubstituted phenyl group, and the substituent includes an alkyl group having 1 to 4 carbon atoms, an alkoxy group and an alkoxycarbonyl group. And an acyl group, or chlorine, bromine, cyano group, nitro group, amino group, hydroxy group, carboxy group and the like. Although the content of phenylisopropenyl ketone contained in the copolymer of the present invention is not limited,
The content can be easily determined from the viewpoint of the kind of the monomer to be copolymerized and the toner suitable for the intended electrophotographic process.

The organic colorant used in the present invention includes
Various dyes and pigments can be used, but color reproducibility,
From the viewpoints of color resistance, electrophotographic properties, etc., cyan is preferably a phthalocyanine type and yellow is preferably a benzidine type. As a phthalocyanine type, color in
dex No (CINo) is CI74160, CI74180, CI7425
5, CI74260, CI74280 and the like are particularly preferable. As benzidine type, CI20190, CI21095, CI21100, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Penzin Yellow G, Penzin Yellow
Particularly preferred are IG, Penzijin Yellow OT, Balkan First Yellow G, Permanent Yellow GR, Shimla First Yellow 5GF and the like. In full-color electrophotography, magenta dyes and pigments preferably used together with the cyan and yellow colors include quinacridone type, rhodamine type and insoluble azo type. CI73915 is particularly preferable as the quinacridone type, and CI45160 is particularly preferable as the rhodamine type. As the insoluble azo type, CI15850 is particularly preferable. The amount of the above-mentioned dye / pigment used in the toner of the present invention is an amount necessary for color reproducibility, and is usually 2 to 10% by weight in the toner.

In addition to the resin of the present invention, the colorant of the present invention,
The photodegradable electrophotographic toner of the present invention can be obtained by mixing a charge control agent, an offset preventing agent and the like. That is, it can be obtained by melt-kneading the above mixture with a twin-screw kneader or the like, further cooling and then finely pulverizing, and if necessary, classifying to a desired particle size. As the charge control agent, a metal chelate of an azo pigment and a salicylic acid compound, a nigrosine pigment, a compound such as a quaternary ammonium salt, or a mixture thereof can be used, but the type and amount that impair the color reproducibility. Should not be used.
As the anti-offset agent, ethylene-based, propylene-based, carnauba, rice oil, and other synthetic and natural waxes or a mixture thereof can be used, and it is usually 2 to 10% by weight in the toner.

It is to be noted that additives such as a fluidity improver, a cleaning property improver and a resistance adjuster may be externally added to these toners. On the other hand, the carrier used together with the toner of the present invention is not particularly limited, but a so-called coated carrier in which ferrite or magnetite particles are coated with a silicone resin, a styrene-acrylic resin or the like can be preferably used. The mixing ratio of the toner and the carrier varies depending on the particle size of the carrier and the developing process of the copying machine used, but the toner concentration (% by weight of the toner contained in the developer) is preferably about 1 to 30%.

Regarding the action of the toner of the present invention, as is clear from the above-mentioned literature, the resin copolymerized with phenylisopropenyl ketone is easily decomposed by ultraviolet rays, so that the printed image on the paper is irradiated with ultraviolet rays. By
The resin in this printed image decomposes into a resin with a lower molecular weight, and as a result, the printed part easily peels off from the paper due to mechanical impact such as compressed air blowing, bending, bending, or scratching. I can guess.

[0016]

【Example】

Production Example 1 Production of Copolymer (a) of Phenyl Isopropenyl Ketone 20 mol% of styrene, 50 methyl ester of methacrylic acid
200 parts of a mixture of mol% and 30 mol% of phenyl isopropenyl ketone, 1 part of ammonium persulfate and neoperex F- which is sodium alkylbenzene sulfonate.
65 (trade name, manufactured by Kao Corporation) was added dropwise to water containing 1 part (as an active ingredient), and then the mixture was stirred at 75 ° C. for 24 hours to obtain a copolymer. 100 parts of the obtained copolymer solution was added to 10 parts of saturated saline solution.
Copolymer (a) was precipitated by pouring into 100 parts, and the obtained copolymer (a) was thoroughly washed with water and dried. Next, 10 parts of the obtained copolymer was dissolved in 100 parts of chloroform, and the solution was poured into 10 times amount of methanol and filtered to obtain the copolymer (a).
Got Copolymer (a) obtained as a result of measurement by GPC
Had a weight average molecular weight of 80,000.

Production Example 2 Production of Copolymer (b) of Phenyl Isopropenyl Ketone The monomer of Production Example 1 was changed to styrene / butyl acrylate / p-chlorophenyl isopropenyl ketone (molar ratio: 50/15/35). Then, in the same manner as in Production Example 1, a phenyl isopropenyl ketone copolymer (b) weight average molecular weight:
Got 80,000.

The effects of the present invention will be more specifically described below with reference to examples, but the present invention is not limited to these. Example 1 The toner of the present invention has an average particle size of 10 μm by the melt-kneading method.
I got m. However, the formulation was based on the following mixing ratio. Copolymer of phenyl isopropenyl ketone (a) 88% by weight Charge control agent: TP-302 (Hodogaya Chemical Co., Ltd.) 3% by weight Colorant: Lionol Yellow 1206 (CI20190. Toyo Ink Mfg. Co., Ltd.) 4% by weight Wax: Viscole 550-P (manufactured by Sanyo Kasei Co., Ltd.) 2.5% by weight External additive: Silica RA-200H (manufactured by Nippon Aerosil Co., Ltd.) 0.5% by weight This toner is used as a silicone resin coated carrier with a toner concentration of 3.5% by weight. % To obtain a developer.

Example 2 Of the formulation of Example 1, instead of the colorant of Example 1,
A toner of the present invention was obtained in the same manner except that RIONOL BLUE SM (CI74160, manufactured by Toyo Ink Mfg. Co., Ltd.) was used. Example 3 A toner of the present invention was obtained in the same manner as in Example 1 except that the phenylisopropenyl ketone copolymer (b) was used in place of the resin of Example 1.

Using the carrier and toner obtained in Examples 1, 2 and 3, a developer having a toner concentration of 3.5% by weight was obtained. Using this developer and toner, a commercially available color copying machine Pixel 200 (manufactured by Canon Inc.) was modified to make 20,000 continuous copies. As a result, good copies were obtained in terms of image density and fog. . Further, filming on the photoconductor was not observed, and the color reproducibility was good. Also,
After leaving the above-mentioned copy in close proximity to a mercury lamp (OSRAM-HBO, 100W) for 1 minute, when it was rubbed with a brush, most of the printed portion came off. As a comparison, a copy of genuine toner of Pixel was placed under the same conditions and then similarly rubbed with a brush, but no change was observed.

Using the paper irradiated with ultraviolet rays as described above, Yasuo Ishizaki et al., Paper and Pulp Technology Times, 13-19, 1990.
The amount of residual toner was determined by the method described in (December issue), and almost no residual toner was found on the recycled paper printed with the toner of the present invention. Many spots of 100 μm or more were observed on recycled paper printed with genuine toner.

[0023]

From the above results, it can be seen that the printed portion copied with the toner of the present invention is easily peeled off by the irradiation of ultraviolet rays, and as a result, the paper can be recycled. Further, it can be seen that in the color copying machine, the toner of the present invention is a toner excellent in color reproducibility.

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Claims (1)

[Claims] 1. An electrophotographic toner comprising a resin, a colorant, a charge control agent and an offset preventive agent, wherein the resin is a copolymer in which at least one of the constituent monomers is phenyl isopropenyl ketone. A photodegradable electrophotographic toner, wherein at least one of the colorants is an organic colorant selected from a phthalocyanine type and a benzidine type.