JPS63108355A - White toner - Google Patents

Abstract

PURPOSE:To enhance the whiteness of a white toner by using a combination of a white pigment and a blue type colorant. CONSTITUTION:The white toner is obtained by dispersing 1-50pts.wt. of the white pigment, such as titanium oxide, and <=5pts.wt. of the blue type colorant into 100pts.wt. of a fixing resin, and when needed, adding additives, such as an electric charge controller. It is preferred to add the blue type colorant in an amount of <=10wt% of the white pigment, thus permitting a yellowish color of the white pigment to be corrected with a blue type colorant in the complementary color reaction to yellow, and enhanced in whiteness.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a white toner used in electrophotography.

(Prior Art and its Problems) In the field of electrophotography, a method of copying an image on colored paper using white toner is known as a simple method of obtaining a so-called reversed image.

In this case, the white toner used is one obtained by dispersing a white pigment such as titanium oxide in a fixing resin medium.

However, this conventionally used white toner has a yellowish tinge and is not completely satisfactory in terms of whiteness.

The reason for this is that the fixing resin itself used as a medium has a slightly palatable taste, and even if the white pigment has sufficient whiteness in the form of large lumps, it tends to take on a yellowish tinge when it is in the form of fine particles. be. In particular, titanium oxide with a rutile crystal structure, which is commonly used as a white pigment, has a strong tendency toward the latter. Therefore, when titanium oxide is dispersed in a resin using a Henschel mixer, the resulting toner has a yellowish tinge. The problem arises that

Therefore, the technical object of the present invention is to provide a white toner with excellent whiteness.

(Structure of the Invention) The white toner of the present invention contains 1 to 50 parts by weight of a white pigment and 5 parts by weight of a blue colorant per 100 parts of a fixing resin medium.
It is dispersed in an amount within parts by weight.

(Function) That is, in the present invention, a yellowish color is created by blending a blue coloring agent that is complementary to yellow.
This color is corrected to white.

In this case, the white toner of the present invention becomes slightly grayish due to the above correction, but white toner is generally used to obtain a negative image on dark colored paper such as black, and the toner image is Since the surrounding area is dark, the color of the toner appears to be extremely white.

(Detailed description of the invention)! 1 As the fixing resin medium, resins used in the production of this type of toner are used, and 1 is particularly preferred.
Various heptano- or diethylenically unsaturated monomers are used, particularly homopolymers and copolymers of (a) vinyl aromatic monomers and (b) acrylic monomers.

Examples of the monomer (a) above include styrene, vinyltoluene, α-methylstyrene, α-chlorostyrene, vinylxylene, vinylnaphthalene, etc.
In addition, the monomer (b) includes acrylic butyrate, methacrylic acid, ethyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 3-hydroxypropyl acrylate, Examples include -hydroxyethyl methacrylate, 3-aminopropyl acrylate, 3-N,N-diethylaminopropyl acrylate, and acrylamide.

Other monomers used in combination with these monomers (a) or (b) or alone include butadiene, isoprene, chloroprene, maleic anhydride, fumaric acid, crotonic acid, Strict examples of other ethylenically unsaturated carposis such as itaconic acid include their esters, vinyl esters such as vinyl acetate, vinylpyridine, vinylpyrrolidone, vinyl ethers, acrylonitrile, vinyl chloride, vinylidene chloride, and the like.

The molecular weight of these resins is 3,000 to 300,000
．． In particular, it is preferably in the range of 5,000 to 200,000.

Separate Plate 1 In the toner of the present invention, known white pigments 1 such as titanium oxide, zinc oxide, antimony oxide, tin oxide, zirconium oxide, zinc sulfide, barium sulfate, lithopone, etc. are used as the white pigment, and these Among these, titanium oxide, particularly titanium oxide having a rutile crystal structure, is most preferably used.

These white pigments are contained at 1 part by weight per 100 parts by weight of the fixing resin medium.
It is used in a proportion of from 2 to 50 parts by weight, especially from 2 to 30 parts by weight. If the amount used is more than the above range, there will be problems such as a decrease in fixing properties, and if it is less than the above range, it will be difficult to achieve a sufficient white color.

In the present invention, by blending a blue coloring agent with a white pigment, the yellowish color that appears in the toner itself due to the pigment acid or resin is corrected to white. do.

As this blue colorant, either a pigment type or a dye type can be used.

Examples of the blue face color 4 include navy blue, cobalt blue, alkali blue blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, fast sky blue,
Examples include Indan Stremburu-BC.

Examples of blue pigments include methylene blue and ultramarine blue.

These blue coloring agents are used in an amount of 5 parts by weight or less, particularly 0,001 to 2 parts by weight, per 100 parts by weight of the fixing resin. When used in an amount larger than this range, the white color of the toner is adversely affected and the toner becomes bluish. Most preferably, within the above range, a weight of white pigment of 1110 or less is used.

The white toner of the present invention contains white or substantially colorless toner compounding agents that do not adversely affect the color of the toner, such as a charge control agent, an anti-offset agent, a pressure fixability imparting agent, and a conductivity imparting agent. are mixed according to a well-known recipe.

As the charge control agent, for the purpose of positive charge control, organic compounds having a basic nitrogen atom, such as basic dyes, aminopyrine, pyrimidine compounds, polynuclear polyamino compounds,
Aminosilanes or fillers surface-treated with aminosilanes are used, and as the negative charge control agent, compounds containing a carboxyl group, such as alkylsalicylic acid metal chelates, are used. These charge control agents are preferably used in an amount of 1 to 10% by weight per toner. In addition, in the method of fixing the toner with a heated roll, anti-offset agents such as silicone oil, low molecular weight olefin resins, various waxes, etc. can be used in an amount of 2 to 15!11i% of the total amount. Further, in applications where the toner is fixed with a pressure roll, a pressure fixing property imparting agent such as paraffin wax, various waxes/vegetable waxes, fatty acid amide, etc. may be used in an amount of 5 to 30% by weight based on the total amount.

In the present invention, a white pigment and a blue colorant are dispersed in a fixing resin medium with a particle size of 5 to 50 IL.
m particles and use it as a toner.

The toner may be manufactured by any means known per se.
For example, the above-mentioned colorant and charge control agent are blended into the fixing resin medium along with other blending aids if necessary, and this is uniformly mixed.
The mixture is uniformly kneaded and then granulated to form a toner. For molding, the above-mentioned mixed mixture is cooled, then pulverized and, if necessary, sieved.

Of course, there is no particular problem in performing rapid mechanical stirring in order to round off irregularly shaped particles.

Alternatively, the fixing resin medium is dissolved in a solvent such as toluene or xylene, and the scaly pigment is dispersed therein.
By spray-drying and granulating the resulting stock solution, toner in the form of spherical particles can be obtained.

Furthermore, a white pigment and a blue coloring agent are dispersed in a solvent that dissolves the monomer but not the resulting polymer, and the monomer is polymerized in this system in the presence of a radical initiator. Toner can also be obtained by As monomers, those exemplified above are preferably used.

(Effects) According to the present invention, a white toner for electrophotography with excellent whiteness is provided.

This white toner is advantageously used for forming white images on young colored paper such as black paper and blue paper.

The invention is illustrated by the following example.

(Example) Cyanine Blue G-3140,3// (manufactured by Dezumi Shiki Co., Ltd.) The above composition was uniformly dispersed using a Henschel mixer FM20B (manufactured by Mitsui Miike Kakoki Co., Ltd.), and then transferred to a twin-screw extruder PCM.
-30 (manufactured by Ikegai Tekko Co., Ltd.), the mixture was melted and kneaded, solidified with cold air, and then coarsely ground in a feather mill (manufactured by Kaiyo Micron Co., Ltd.). This coarsely pulverized product was pulverized using a jet mill ID5-5 model (manufactured by Nippon Pneumatic Co., Ltd.), and then finely powdered (particle size 54
m or less) to obtain a toner with an average particle size of 11p and m.

Hydrophobic silica R972 is added to this toner as a fluidity imparting agent.
(manufactured by 8 Woodworking Logil Co., Ltd.) was added in an amount of 5 parts by weight, surface treatment was performed using a Henschel mixer, and aggregates were removed using a vibrating sieve to obtain a product toner.

This white toner and ferrite carrier (average particle size 70μ)
m; manufactured by Nippon Tetsuko Co., Ltd.) using a Nauta mixer (manufactured by Kaiyo Micron Co., Ltd.) to obtain a developer having a toner concentration of 45%.

The above developer was put into a copying machine D C-111 manufactured by Sanda Kogyo Co., Ltd., and blue transfer paper (L = 33° ago by Lab measurement method,
b=-18) and ordinary white transfer paper. As a result, clear, high-quality white images were obtained on each transfer paper. La the white image area on the white transfer paper
As a result of measurement using the b method, L+58a3, ax-(L8
, bxzo, it was confirmed that the image was an almost achromatic white image with high whiteness.

(Comparative example) On the outside of the toner of the above example, cyanine blue G3
A developer was obtained in exactly the same manner except that it did not contain No. 14, and was set in a copying machine manufactured by Sanda Kogyo Co., Ltd. @DC-111 for copying. As a result, the image on the white transfer paper appeared to have a yellowish tinge, and as a result of measurement using the Lab method, L = 92.
．． 3, a=α3. It was found that b = 12.6 and it had a considerable yellowish tinge.

Claims (3)

[Claims] (1) 1 white pigment per 100 parts by weight of fixing resin medium
A white toner characterized in that a blue colorant is dispersed in an amount of 50 parts by weight or less and a blue colorant in an amount of 5 parts by weight or less. (2) Claim 1 in which the white pigment is titanium oxide
White toner as described in section. (3) The white toner according to claim 1, wherein the blue colorant is blended in an amount of 1/10 or less of the weight of the white pigment.