JPH0157905B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a developer for developing latent images in electrophotography, electrostatic recording, electrostatic printing, magnetic recording, etc. More specifically, the present invention relates to an electrophotographic developer 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. A number of conventional electrophotographic methods are known, such as those disclosed in U.S. Pat. No. 2,297,691, but generally a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means. Then, the latent image is developed using developer powder (hereinafter referred to as toner), and the toner image is transferred to a transfer material such as paper as necessary.
Copies are obtained by fixing by heat, pressure, or solvent vapor. 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 U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. No. 2,618,552, and U.S. Pat.
The powder cloud method described in U.S. Pat.
A method using conductive magnetic toner described in Japanese Patent No. 3909258 is 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. In the case of a system using a so-called two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder. Positive charge control agents used in such dry developing toners include, for example, generally quaternary ammonium compounds and organic dyes, particularly basic dyes and their salts. Common positive charge control agents include benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine, safranin gamma and crystal violet. In particular, nigrosine base and nigrosine are often used as positive charge control agents. These are usually added to thermoplastic resins, heated, melted and dispersed, and pulverized.
It is used after adjusting the particle size to an appropriate size as required.
However, these dyes used as charge control agents have complex structures, inconsistent properties, and poor stability. In addition, decomposition during thermal kneading, mechanical impact,
It is easily decomposed or altered by friction, changes in temperature and humidity conditions, etc., and tends to cause a phenomenon in which charge controllability is deteriorated. Therefore, when a toner containing these charge control agents is used for development in a copying machine, as the number of copies increases, the charge control agent decomposes or changes in quality, which may cause deterioration of the toner during durability. Furthermore, many positive charge control agents are hydrophilic, and due to poor dispersion in these resins, dyes are exposed on the toner surface when the agent is melted and kneaded and then crushed. Therefore, when the toner is used under high humidity conditions, it has the disadvantage that good quality images cannot be obtained because these control agents are hydrophilic. In this way, when a conventional positive charge control agent is used in toner, it can be applied to the surface of toner particles between toner particles, between toner and carrier, or between toner and toner carriers such as sleeves. The amount of charge generated varies, and problems such as development fog, toner scattering, and carrier contamination are likely to occur.
Further, this problem becomes a noticeable phenomenon when a large number of copies are made, and the result is that the copying machine is not suitable in practice. Furthermore, under high humidity conditions, the transfer efficiency of toner images decreases significantly, and many of them become unusable. Furthermore, even at room temperature and humidity, when the toner is stored for a long period of time, it often deteriorates and becomes unusable due to the instability of the positive charge control agent used. Furthermore, most of these charge control agents are divided, and it is currently difficult to apply them to positively charged color toners. An object of the present invention is to provide a developer having positive chargeability. A further object of the present invention is to provide a developer that maintains its initial characteristics even when the developer is used continuously over a long period of time, and that causes no toner aggregation or change in charging characteristics. Another objective is to develop a developer that reproduces stable images unaffected by changes in temperature and humidity, especially a developer that has high transfer efficiency and does not cause scattering or transfer dropouts during transfer at high or low humidity. It's on offer. Still another object is to provide a developer with excellent storage stability that maintains its initial characteristics even during long-term storage. Still another object is to provide a colorless charge control agent for color toners that exhibits positive chargeability. Specifically, the present invention relates to a positively charged developer characterized in that a silicone oil having an amine in a side chain is added to toner particles. Furthermore, the present invention provides a positively charged developer containing a magnetic toner in which a silicone oil having an amine in a side chain is added to the toner particles, or a positively charged developer containing a magnetic toner in which a silicone oil having an amine in a side chain is added to the toner particles. The present invention relates to a developing method characterized by developing an electrostatically charged image with a positively charged developer containing a non-magnetic toner and a carrier. As the silicone oil having an amine in its side chain, silicone oil containing a structural unit represented by the formula () can generally be used. (Here, R ₁ represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, and R ₂ represents an alkylene group,
It represents a phenylene group, and R ₃ and R ₄ represent hydrogen, an alkyl group or an aryl group. However, the above alkyl group, aryl group, alkylene group, and phenylene group may contain an amine, or may have a substituent such as a halogen within a range that does not impair chargeability. ) Preferred commercially available silicone oils having an amine in their side chains include, for example, amino-modified silicone oils represented by the following structural formula. it is, (Here, R ₁ represents an alkyl group or an aryl group, R ₅ and R ₆ represent an alkyl group, an aryl group, or a hydroxyl group, R ₂ represents an alkylene group, a phenylene group, or an alkylene group containing an amine, and R ₃
represents hydrogen, an alkyl group, or an aryl group. m,
n is a number of 1 or more. ), specifically the following are preferred, and these may be used alone or in a mixture of two or more.

[Table] Manufactured by the company)
The amine equivalent in the above table is the equivalent per amine group (g/eqiv.), which is the value obtained by dividing the molecular weight by the number of amines per molecule. In particular, the amine equivalent is 25,000 or less as mentioned above (for example, 225,000
~320) is preferred, and 5000 or less is particularly preferred. Furthermore, as mentioned above, silicone oil with amine in the side chain has a viscosity of 20 to 3500 cps at 25°C.
Those having the following are preferable in terms of control of positive chargeability, environmental stability, and development characteristics. Since the modified silicone oil used in the present invention is colorless or pale white, when applied to a positively charged color developer, a color developer with a very clear tone can be obtained. In addition, the modified silicone oil used in the present invention is stable and has a heat resistance temperature of about 300°C, and is extremely resistant to decomposition or deterioration due to thermal or mechanical shock, and does not cause problems such as a decrease in charge controllability. There are no problems, and toner deterioration during durability is significantly reduced. Furthermore, the modified silicone oil used in the present invention has strong positive chargeability and high humidity stability.
It has good positive chargeability even under high humidity, and clear images can be obtained. In the present invention, silicone oil having an amine in the side chain can be added to the toner and used, and favorable results are obtained when using 0.01 to 30% by weight based on the weight of the toner, and 0.02 to 10% by weight. %
Gives particularly good results when used. Examples of the binder resin of the toner that can be used in the present invention include monopolymers of styrene and substituted products thereof such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers, and styrene-propylene copolymers. 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 copolymer Copolymer, styrene-vinylethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer , styrenic copolymers such as styrene-maleate ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin , rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. can be used alone or in combination. Colorants used in toners include a wide range of well-known dyes and pigments, such as carbon black, phthalocyanine blue, indanthrene blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, and benzidine yellow. can be used. In order to use the toner as a magnetic toner, it may contain magnetic powder. Such magnetic powders are materials that are magnetized when placed in a magnetic field, such as powders of ferromagnetic metals such as iron, cobalt, and nickel, or alloys and compounds such as magnetite, γ-iron oxide, and ferrite. be. The content of this magnetic powder is 15 to 70% by weight based on the weight of the toner. Toner can be prepared using iron powder, glass beads, or
It is mixed with carrier particles such as nickel powder or ferrite powder and used as a developer for electrical latent images. The developer of the present invention can be applied to various developing methods. For example, magnetic brush development method, cascade development method, method using conductive magnetic toner described in U.S. Pat. No. 3,909,258, JP-A-53-
Method using high-resistance magnetic toner described in Publication No. 31136, Japanese Patent Application Laid-open No. 54-42121, Publication No. 55-18656
There are methods described in Japanese Patent Application Publication No. 54-43027, a fur brush development method, a powder cloud method, a touch-down development method, an impression development method, and the like. Example 1 Styrene-butyl methacrylate (weight ratio 7:
3) 100 parts by weight of copolymer, 60 parts by weight of magnetite,
3 parts by weight of polyethylene wax and 1.2 parts by weight of amino-modified silicone oil (viscosity at 25°C, 70 cps, amine equivalent: 830) were mixed and melt-kneaded in a roll mill. After cooling, it is roughly pulverized in a hammer mill, and then finely pulverized in a jet pulverizer. Then, the powder was dispensed using a wind dispenser to obtain a fine powder (toner) having a particle size of 5 to 20 μm. A positively charged developer was prepared by adding and mixing 0.4 parts by weight of coidal silica to 100 parts by weight of this fine powder. When this positively charged developer was applied to a commercially available copying machine (trade name: Minicopia PC20, manufactured by Canon), clear images without fog were obtained. Example 2 Styrene-butyl methacrylate (weight ratio 7:
3) 100 parts by weight of copolymer, 50 parts by weight of γ-iron oxide,
The same procedure as in Example 1 was carried out except that 4 parts by weight of polyethylene wax and 1 part by weight of amino-modified silicone oil (viscosity at 25°C, 3500 cps, amine equivalent 3800) were used, and a clear sepia color with no fog was obtained. Image obtained. Example 3 Styrene-butyl methacrylate (weight ratio 7:
3) 80 parts by weight of copolymer, 20 parts by weight of styrene-butadiene (weight ratio 85:15) copolymer, 5 parts by weight of phthalocyanine blue, 4 parts by weight of low molecular weight polypropylene
0.8 parts by weight of amino-modified silicone oil (viscosity 3500 cps at 25°C, amine equivalent 3800) were mixed, and the same procedure as in Example 1 was carried out to obtain a toner having a particle size of about 5 to 20 μm. 12 parts by weight of this toner and 88 parts by weight of Carrier Iron Powder (trade name, EFV250/400 manufactured by Nippon Tetsuko Co., Ltd.) were mixed to prepare a developer. On the other hand, a negative electrostatic latent image is formed on the OPC photoconductor, this is developed with the above developer, and the resulting powder image is transferred to plain paper. and a pressure roll whose surface was coated with silicone rubber). A clear blue image with no fog was obtained. Examples 4 to 6 (viscosity at 25°C, amine equivalent) were (3500 cps, 2000), (90 cps, 8800), (60 cps,
Example 1 was carried out in substantially the same manner as in Example 1, except that amino-modified silicone oil (22500) was used, and good results were obtained. Comparative Examples 1 to 3 Examples 1 to 3 were carried out in the same manner as in Examples 1 to 3 except that the amino-modified silicone oil was not used, but only poor images were obtained.

[Table] Comparative Example 4 Dimethyl silicone oil (viscosity 50 cps at 25°C) was used instead of amino-modified silicone oil, which is a silicone oil with amine in the side chain.
A developer was prepared in the same manner as in Example 1, except that a developer was used, and an image was produced in the same manner as in Example 1. As a result, the image density was 0.19, and the image was thin and poor.

Claims (1)

[Scope of Claims] 1. A positively charged developer characterized in that silicone oil having an amine in a side chain is added to toner particles. 2 Silicone oil with amine in the side chain is
The following structural units [In the formula, R ₁ represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, and R ₃ and R ₄ represent hydrogen, an alkyl group, or an aryl group. ] The positively charged developer according to claim 1. 3 Silicone oil with amine in the side chain is
Amine equivalent 320~22500 and viscosity at 25℃ 20~
The positively charged developer according to claim 1 or 2, which has a power of 3500 cps. 4 A positively charged developer containing a magnetic toner in which a silicone oil having an amine in the side chain is added to the toner particles, or a non-magnetic developer in which a silicone oil having an amine in the side chain is added to the toner particles. A developing method characterized by developing an electrostatically charged image with a positively charged developer containing toner and carrier. 5 Silicone oil with amine in the side chain is
The following structural units [In the formula, R ₁ represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, and R ₃ and R ₄ represent hydrogen, an alkyl group, or an aryl group. ] The developing method according to claim 4. 6 Silicone oil with amine in the side chain is
Amine equivalent 320~22500 and viscosity at 25℃ 20~
The developing method according to claim 4 or 5, which has 3500 cps.