JPS59189350A - Positively chargeable electrophotographic toner - Google Patents

Abstract

PURPOSE:To provide an electrophotographic develope positively chargeable unifomly and strongly and capable of developing a negative electrostatic charge image and forming a high quality image by incorporating a positively chargeable polymer obtained by copolymerizing a specified monomer and styrene monomer in a binder. CONSTITUTION:A positively chargeable electrophotographic toner contains in a toner binder a 5-50wt% copolymer of a monomer represented by the shown formula (R1, R4, R5 are each H or alkyl, and R2, R3 are each alkyl) and styrene monomer in a molar ratio of (0.1-10):(99.9-90). As a result, uniform dispersion of a positve charge controller into the toner and hygroscopicity of the toner in high humidity are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer for developing silently charged images in electrophotography, electrostatic recording, electrostatic printing, and the like.

More specifically, the present invention relates to an electrophotographic toner that is uniformly and strongly positively charged, visualizes a negative electrostatic charge image, and provides a high-quality image in a direct or indirect electrophotographic development method.

Conventionally, many electrophotographic methods have been known, such as those disclosed in U.S. Pat. , and then develop the latent image using developer powder (hereinafter referred to as toner), transfer the toner image to a transfer material such as paper as necessary, and then heat, pressure, or solvent vapor to transfer the toner image to a transfer material such as paper. It is used to fix and obtain copies. Further, when a step of transferring a toner image is included, a step for removing residual toner on the photoreceptor is usually provided.

Development methods for visualizing electrical latent images using toner include, for example, the magnetic brush method described in US Pat. No. 2,874.063, the cascade development method described in US Pat. No. 2,618,552, and US Pat. Powder cloud method described in No.
A method using a conductive magnetic toner described in Japanese Patent No. 58, a method using various insulating magnetic toners described in Japanese Patent Publication No. 41-9475, etc. are known.

As toners applied to these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 μm are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used.

Examples of positive charge control agents used in such dry magnetic toners include organic dyes, particularly basic dyes and their salts.

Common positive charge control agents include benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine hydrochloride, safranin r, and crystal violet.

In particular, nigrosine [1] and nigrosine hydrochloride are often used as positive charge control agents. These are usually added to a thermoplastic resin, heated and melted and dispersed, and then finely ground to adjust the particle size to an appropriate particle size as necessary before use.

However, these dyes used as charge control agents have complex structures, inconsistent properties, and poor stability. Unfortunately, it decomposes or changes in quality due to decomposition during thermal kneading, mechanical impact, friction, changes in temperature, humidity, and other conditions, resulting in a phenomenon in which charge controllability decreases. Therefore, when a toner containing these dyes as a charge control agent is used for development in a copying machine, the dye decomposes or changes in quality as the number of copies increases, causing deterioration of the toner during durability.

Furthermore, since it is extremely difficult to uniformly disperse these dyes as charge control agents in thermoplastic resins, this has the fatal drawback of causing a difference in the amount of triboelectric charge between toner particles obtained by pulverization. have. For this reason, various methods have been used to more uniformly disperse these dyes into resins. For example, basic nigrosine dyes are used by forming salts with higher fatty acids in order to improve their compatibility with thermoplastic resins, but unreacted fatty acids or salt dispersion products often remain on the toner surface. When exposed, it contaminates the developing sleeve and the like, causing a decrease in toner fluidity, fog, and a decrease in image density. Alternatively, in order to improve the dispersion of these dyes into the resin, a method has been adopted in which the dye powder and the resin powder are first mechanically pulverized and mixed, and then the mixture is heat-melted and kneaded.
The reality is that the inherent poor dispersion cannot be avoided, and that sufficient uniformity of charge has not yet been obtained for practical use. For the purpose of improving the dispersion of such a positive charge control agent into a toner binder, Japanese Patent Application Laid-Open No. 50-39550 and Japanese Patent Application Laid-open No. 453-
57841, etc., a method is known in which a resin containing a positively charged functional group is used as a substitute for a charge controllable dye or pigment.

However, since these positively charged resins are generally hydrophilic, they absorb moisture and reduce the resistance of the toner especially in a humid environment, causing problems such as fogging and toner scattering. Moreover, these phenomena become particularly noticeable when a large number of copies are made, and the result is practically unsuitable for copying machines.

(5) Furthermore, under high humidity conditions, the transfer efficiency of toner images decreases significantly, making it unusable.

Furthermore, even at room temperature and humidity, when the toner is stored for a long period of time, the toner often aggregates and becomes unusable due to the instability of the positive charge control dye used.

The present inventors have solved the various problems associated with conventional positively charged toners as described above, and have developed an electronic toner that is uniformly and strongly positively charged, visualizes a negative electrostatic charge image, and produces high-quality images. As a result of intensive research aimed at providing a photographic developer, we found that a toner binder contains 5 to 10 moles of a copolymer of a monomer represented by the general formula and 99.9 to 90 moles of a styrene monomer. It has been found that by containing 50 wt% (6), the positive charge control agent can be uniformly dispersed in the toner and the hygroscopicity of the toner under high humidity can be improved.

In the copolymer contained in the above positively charged toner, the monomer represented by the above general formula is 01
If the amount is more than 1 mole, positive triboelectric properties can be imparted to the toner, but if it is more than 10 moles, the environmental dependence becomes poor, and the toner becomes especially hygroscopic. However, if this copolymer is contained in the toner binder in an amount of 5 wt % or more, sufficient positive charge controllability can be imparted to the toner.

As positively charged resins that can be used in the present invention, 2
~Dimethylamino-2-methylprogyl methacrylate, 2-dimethylamine-2-ethylbutyl methacrylate, 2-dimethylamine-2-f lobylhexyl methacrylate, 2-dinitylamino-2-methylglobil methacrylate. ), 2-diethylamino-2-ethylzotyl methacrylate, 2-diethylamine-2-
Examples include f-lovirhexyl methacrylate.

The following resins can be used in blend with the above positively charged resin. In other words, the moon as a binder resin for toner? Listyrene, poly-P-chlorostyrene, polyvinyltolueneNatonostyrene and its substituted monopolymers; styrene-P-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene Copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene -Ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-alpha chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Vinyl methyl ether co-ft polymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isolone copolymer, styrene-acrylonitrile-indene copolymer, styrene - Styrenic copolymers such as maleic acid copolymers and styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polynolopyrene, polyester, polyurethane, polyamide, epoxy Resin, Iriginylbraral, polyacrylic acid resin, Ronone, modified rosin, chilled resin,
Phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, black-fin waxes, and the like can be used alone or in combination. Coloring agents used in the present invention include carbon black, nigrosine dye, Lang black, Sudan Blafuku SM, First Yellow 01 Benzidine Yellow, Pigment Yellow, Indo First Orange, Irgazine Red,
Noya lanitroaniline red, toluidine red,
Carmine FB, Permanent Bordeaux FRB, Pigment Orange R, Lysole Red 2G, Lake Red C1 Rhodamine FB.

(9) Rhodamine B Lake, Methyl Piolet) B Lake,
Phthalocyanine Blue, Bigmen) 7% Roux, Prilliant Green B, Phthalocyanine Green, Oil Yellow GG, Zapon Fast Yellow CGG,
Kaya set Y963. Kayaset YG.

Sumigelast Yellow 〇G, Zapon First Orange RR, Oil Scarlet, Sumigelast Orange G
1 Orazole Brown B1 Pomelo First Scarlet) CG, Eisenspiron Red BEH, Oil Gink OP, etc.

Furthermore, when used as a magnetic toner, ferromagnetic elements and alloys and compounds containing these, such as iron, cobalt, nickel, manganese, etc., such as magnetite, hematite, and ferrite, may be used as magnetic powder. The material may contain about 1 to 80% by weight of fine powder of a substance conventionally known as a ferromagnetic material, such as ferromagnetic alloys and other ferromagnetic alloys, with an average particle size of about 0.1 to 5 microns.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(10) Example] Styrene-n-butyl methacrylate resin
90 parts carbon black (Mitsubishi Kasei +44)
5 parts The above formulation was kneaded using a roll mill, cooled, pulverized by jet pulverization, and then classified to obtain a toner of 5 to 25 μm. 8 parts of this toner and 1 iron powder (Japanese iron powder EFV 250-400 mesh)
00 parts and stirred for 30 minutes with a V-type mixer, then put into NP8500 Suha (manufactured by Canon) PA and mix 20 parts.
When 100,000 sheets were continuously copied under an RH atmosphere of 60 degrees Celsius, the 100,000th sheet was almost the same as the starting image and a clear image was obtained, with only slight fluctuations in image density. Clear images were also obtained when a similar test was conducted at 35° C. and 85% RH. The results are shown in the table below.

(11) Image quality and background density comparison example 1 A toner of 5 to 25 tt was prepared in the same manner as in Example 1, and 100,000 sheets were continuously copied under each environment in the same manner as in Example 1. (At 5° C. and 85% RH, capri occurred on the background as well as the number of copies. The results are shown in the following table.

(12) Example 2 10 parts of styrene and 2-methylamino-2-ethylbutyl methacrylate in a molar ratio of 95:5 90 parts of copolymer styrene-n-butyl methacrylate resin The above mixture was kneaded using a roll mill, and after cooling. After being finely pulverized by Noet pulverization, it is classified to
A 5μ toner was obtained. Mix 8 parts of this toner with 100 parts of iron powder (Japanese iron powder F2FV 250-400 mesh), stir for 30 minutes with a V-type mixer, and put the mixture into an NP-8500 Super (Canon) machine. A test was conducted on 100,000 sheets in an atmosphere of 20°C (601 R) (20°C, 601 R), and the 100,000th sheet was almost the same as the starting one.A similar test was conducted at 35°C, 85 S.
Even when the printing was carried out under an RH atmosphere, good images were obtained that were almost the same as those obtained under an atmosphere of 20° C. and 65%, and no background stains were noticed even after 100,000 sheets were cut.

Comparative Example 2 A toner was prepared in the same manner as in Example 2 with the above blending ratio, and 2
IO under each environment of 0℃60℃RH and 35℃85℃RH
After continuous copying of 10,000 sheets, a clear image was obtained at 20° C. and 60% RH, but at 35° C. and 85% RH, the density increased with the number of durable sheets and the background density increased.

The test results of Example 2 and Comparative Example 2 are shown in the following table.

(14) Example: 3 Copolymer methacrylate magnetite (Titan Kogyo Co., Ltd. BL-270) of 1-0 parts of nona 1/n and 2-methylamino-2-glopyhexyl in a molar ratio of 90:10 60
The above materials are melt-kneaded, cooled, pulverized, and classified to give 5 to 2
The toner was 5μ. When this toner was placed in PC-20 (manufactured by Canon) and developed in an environment of 20° C. and 60%, a good quality image with high image density was obtained and did not deteriorate even after 2000 copies were made. Separately, under an environment of 30°C and 85%
When continuous copying of 0 sheets was carried out, good images were obtained which were almost the same as those obtained under the environment of 20° C. and 60° C.

Comparative Example 3 In place of the 90:10 copolymer of styrene and 2-dimethylamino-2-chlorohydrhexyl in Example 3, 80:
The results of a similar test using a copolymer of No. 20 are shown in the table below.

Claims (1)

[Scope of Claims] The binder contains 5 to 5 Q wt% of a positively charged polymer obtained by copolymerizing 01 to 10 moles of heptamine represented by the general formula and 99.9 to 90 moles of styrene monomer. A positively charged toner for electrophotography.