JP2673572B2 - Toner for developing electrostatic images - Google Patents

Description

The present invention relates to a novel toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like, and a charge control agent for the toner.

[Prior Art] Various conventional electrophotographic methods are described in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748.

Developing methods applied to the electrophotographic method and the like are roughly classified into a dry developing method and a wet developing method. The former is further classified into a method using a two-component developer and a method using a one-component developer.

Conventional toners applied to these dry development methods include:
Fine powders in which dyes and pigments are dispersed in natural or synthetic resins are used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and finely pulverized to about 1 to 30 μm are used as toner. As the magnetic toner, a toner containing magnetic particles such as magnetite is used. In the case of using a two-component developer, the toner is usually used by being mixed with carrier particles such as glass beads and iron powder.

Any toner must have a positive or negative charge, depending on the polarity of the electrostatic latent image to be developed.

In order to cause the toner to retain electric charge, it is possible to use the frictional charging property of the resin, which is a component of the toner.However, since the charging property of the toner is small, an image obtained by development is easily fogged and unclear. Becomes Therefore, in order to further impart triboelectricity to the toner, a substance called a charge control agent is generally added.

Today, the charge control agents known in the art include, as negatively triboelectric ones, metal complex salts of monoazo dyes, metal complex salts of salicylic acid, metal complex salts of naphthoic acid, metal complex salts of dicarboxylic acid, copper phthalocyanine pigments and so on.

[Problems to be Solved by the Invention] Many of the charge control agents described above have a sufficiently high charge providing ability, but are colored and cannot be used for color toner. In addition, since certain control agents easily contaminate a toner carrier such as a sleeve or a carrier, the toner using the toner decreases the triboelectric charge amount with an increase in the number of copies and causes a decrease in image density. Easy to do. Further, since the amount of triboelectric charge of a certain control agent greatly varies depending on the binder resin used, there are restrictions on the binder resin or other materials that can be used. Further, although excellent in triboelectricity, many of them are poor in controllability and are likely to be excessive.

At present, there is a strong demand for the development of charge control agents that satisfy all of these.

An object of the present invention is to provide an excellent toner using a charge control agent that solves the above problems.

That is, the triboelectric charge amount between the toner particles, between the toner and the carrier, between the toner and the toner carrier such as the sleeve in the case of one-component development is stable and does not change with temperature and humidity. A toner capable of reproducing a stable image that is not affected by changes.

A further object of the present invention is to provide a developer in which the toner is uniformly dispersed or compatible with the binder resin and the toner particles are uniformly charged to give a clear image without fogging.

[Means and Actions for Solving the Problem] A feature of the present invention is to use a condensate of salicylic acid having a substituent as a charge control agent.

JP-A-63-33755 discloses a two-component toner containing salicylic acid and a metal salt of a salicylic acid compound.

However, salicylic acid itself has sublimation properties and is not sufficiently negatively chargeable, so its use is very limited. On the other hand, some metal complexes of salicylic acid compounds have excellent triboelectric charging properties and are generally widely used. However, the triboelectric charging property of the metal complex does not depend only on the ligand, and the charge amount often changes to the plus or minus sign depending on the central metal. Therefore, it is impossible to predict the triboelectric charging property of the ligand from the result of the metal complex.

The inventors of the present invention have studied salicylic acid derivatives based on an original idea, and have found that the amount of negative triboelectric charge can be increased by introducing a substituent into salicylic acid. However, these salicylic acid derivatives also have sublimability similar to salicylic acid, and are not suitable for producing toner at high temperature. Therefore, when these are condensed as monomers, the sublimability is lost, and the amount of negative triboelectricity of the toner is higher than that of the corresponding monomer, and it can be regarded as colorless or substantially colorless. The present invention has been achieved by finding that it is so pale.

Further, since the dispersibility in the binder resin is improved as compared with the metal complex, contamination of the toner carrier such as the sleeve and carrier can be reduced.

Examples of the monomer used for synthesizing the condensate of a salicylic acid having a substituent of the present invention include salicylic acid having a substituent represented by the formula (I).

R ¹ and R ² each independently represent an alkyl group, an amino group, a hydroxyl group, a carboxy group, an alkoxy group, a carbonyl group, an aryl group, a halogen atom or an acyl group, and either one may be a hydrogen atom.

Specific examples are shown below, but these are representative examples in consideration of the ease of the alloying method and the like, and do not limit the compounds of the present invention in any way.

Further, a compound obtained by condensing different kinds of salicylic acid derivatives also has a good negative triboelectric charging property, but in this case, it is a mixture of three kinds including a condensate of two kinds of the same salicylic acid derivative.

In the present invention, sublimation could be suppressed by condensing salicylic acid and polymerizing it. Further, by using a condensate, the triboelectric charge amount can be remarkably increased as compared with the corresponding salicylic acid derivative, and it can be brought close to the electric charge amount of the metal complex, and it has reached a level where there is no problem in practical use. Moreover, since the dispersibility in the resin is improved as compared with the conventional metal complex, the contamination of the toner carrier such as the sleeve and the carrier is reduced.

As described above, the dehydrated condensate of salicylic acid having a substituent of the present invention has excellent properties which are not required for conventional charge control agents.

The condensate of salicylic acid having a substituent of the present invention can be obtained by reacting a salicylic acid derivative with a dehydrating agent such as phosphorus trichloride.

As a method of incorporating the condensate of a salicylic acid having a substituent of the present invention into a toner, there are a method of adding it inside the toner and a method of adding it externally. The amount of these compounds used is
The type of the binder resin, the presence or absence of additives used as necessary, is determined by the toner manufacturing method including the dispersion method, and is not limited to a specific one, but is preferably a binder resin 100. It is used in an amount of 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight based on parts by weight. When externally added, the amount is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the resin, and it is particularly preferable that the resin is fixed to the surface of the toner particles by mechanochemical treatment.

Further, the compound used in the present invention can be used in combination with a conventionally known charge control agent.

Examples of the coloring agent used in the present invention include carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6G, lake,
Calco oil blue, chrome yellow, quinacridone,
Conventionally known dyes and pigments such as benzidine yellow, rose bengal, triarylmethane dyes, monoazo dyes and disazo dyes may be used alone or in combination.

Examples of the resin used in the present invention include polystyrene, poly-p-chlorostyrene, polyvinyltoluene and other styrenes and substituted homopolymers thereof; styrene-p.
-Chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethylmethacrylate copolymer Polymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Styrene-based copolymers such as styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester Tree , Polyurethane, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resin, coumarone-indene resins, and petroleum resins.

Further, a crosslinked styrene copolymer is also a preferable binder resin.

Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and methacrylic. Acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, monocarboxylic acid having a double bond such as acrylamide or the like; for example,
Dicarboxylic acids having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like, and substituted products thereof; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; Olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Monomers may be used alone or in combination of two or more.

Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene, or the like; for example, ethylene glycol diacrylate, ethylene glycol diacrylate, or the like. Double bonds such as methacrylate, 1,3-butanediol dimethacrylate
Carboxylic acid esters having two or more compounds; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups are used alone or as a mixture.

When a pressure fixing method is used, a binder resin for a pressure fixing toner can be used. For example, polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer can be used. Coalescent, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, paraffin and the like.

The toner of the present invention contains a magnetic material and can be used as a magnetic toner. Examples of the magnetic material contained in the magnetic toner of the present invention include iron oxides such as magnetite, γ-iron oxide, ferrite and iron-excessive ferrite; metals such as iron, cobalt and nickel; or metals such as these and aluminum and cobalt; Examples thereof include alloys with metals such as copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten and vanadium, and mixtures thereof.

These ferromagnetic substances preferably have an average particle diameter of 0.1 to 1 μm, preferably about 0.1 to 0.5 μm, and the amount contained in the magnetic toner is 40 to 1 part by weight per 100 parts by weight of the resin component.
50 to 100 parts by weight, preferably 100 to 100 parts by weight of the resin component.
Parts by weight.

Further, when the toner of the present invention is used as a two-component developer, it is used by mixing with a carrier powder. As the carrier that can be used in the present invention, known carriers can be used, for example, iron powder, ferrite powder, magnetic powder such as nickel powder, glass beads, and the like, and those obtained by treating the surface with a resin or the like. And so on.

The toner of the present invention may optionally contain additives. Examples of the additive include a lubricant such as zinc stearate; an abrasive such as cerium oxide and silicon carbide; a fluidity imparting agent such as silica fine powder and aluminum oxide; a caking inhibitor; or a carbon black and tin oxide. There is a conductivity imparting agent.

Further, a fluorine-containing polymer fine powder such as a polyvinylidene fluoride fine powder is also a preferable additive from the viewpoint of fluidity, abrasiveness, charge stability and the like.

Further, in order to improve the releasability at the time of hot roll fixing, a wax-like substance such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sasol wax, paraffin wax, etc.
Addition of about 5% by weight to the toner is also a preferred embodiment of the present invention.

In producing the toner according to the present invention, the above-mentioned toner constituent materials are sufficiently mixed by a ball mill or other mixer, then kneaded well using a heat kneader of a hot roll kneader or an extruder, and cooled and solidified. A method of obtaining a toner by mechanical pulverization and classification is preferable. Alternatively, a method of dispersing a constituent material in a binder resin solution and then spray-drying to obtain the toner; or a method of forming the binder resin A polymerized toner production method in which a predetermined material is mixed with a monomer to form an emulsified suspension and then polymerized to obtain a toner; or in a so-called microcapsule toner comprising a core material and a shell material, a core material or a shell material. ,
Alternatively, a method of including a predetermined material in both of them can be applied. Further, if necessary, the desired additive is sufficiently mixed with a mixer such as a Henschel mixer to produce the toner according to the present invention.

The toner of the present invention can be used for development for visualizing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, by a conventionally known means.

The salicylic acid condensate having a substituent of the present invention is colorless or light-colored and has a negative triboelectric chargeability to the same extent as a conventionally known metal complex. Moreover, the dispersibility in the binder resin was improved as compared with the metal complex. Further, the sublimation property of salicylic acid or a salicylic acid derivative could be safely solved.

Therefore, the toner containing the condensate of a salicylic acid having a substituent of the present invention as a charge control agent can always provide a good and stable image because the toner carrier such as a sleeve or a carrier is less contaminated. It can also be used as a charge control agent for color toners and can provide a vivid color image. Since it has no sublimation property and is excellent in thermal stability, it is possible to stably produce and supply the toner without any special measures in the toner manufacturing process and in selecting other raw materials.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. All parts in the following formulations are parts by weight.

Synthesis Example 1 (Compound of Compound Example) 25 g (0.1 mol) of 3,5-di-tert-butylsalicylic acid
Dissolve in 200 ml of acetone and raise the temperature to 50 ° C. Under stirring 21.
About 1 g of 6 g (0.1 mol) dicyclohexylcarbodiimide
Drip over time. After completion of dropping, the mixture is stirred at 50 to 55 ° C for 5 hours and then cooled to around 20 ° C to remove insoluble matter.
After concentrating the liquid, the obtained crystals are recrystallized from hexane-acetone to obtain 18.5 g of white powder having a melting point of 225.5 to 230.5 ° C.

Synthesis Example 2 (Compound Example Compound) 15.4 g (0.1 mol) of 5-hydroxysalicylic acid 2.5 g
(0.02 mol) phosphorus trichloride and 200 ml toluene are heated to 60 ° C. with stirring in a nitrogen stream. Continue stirring at 60-70 ° C for about 3 hours until HCl evolution is complete. After cooling to 20 ° C., 5% Na ₂ COS ₃ is added to neutralize. The crystals obtained are recrystallized from acetone to give a white powder.
Get 9.5 g.

Example 1 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified by a fixed wall type air classifier. The classified powder was purified.

Furthermore, the obtained finely divided powder is strictly classified at the same time using a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) that utilizes the Coanda effect to remove black powder with a volume average particle size of 10.9 μm. Fine powder (magnetic toner) was obtained.

0.4 parts of silica fine powder hydrophobized with silicone oil was added to 100 parts of the obtained black fine powder, and mixed with a Henschel mixer to obtain a negatively chargeable one-component magnetic toner.

Commercially available electrophotographic copying machine NP-8570 (manufactured by Canon Inc.)
The magnetic toner obtained in the above was subjected to a copy test.

In an environment with a temperature of 23 ° C and a relative humidity of 60%, the initial concentration is 1.38.
A clear image of was obtained. Image density after 10,000 copies
It was a good 1.35. Further, when the triboelectric charge amount of the toner on the developing sleeve was measured, it was -7.
7 μc / g, −6.0 μc / g after copying 10,000 sheets, and no remarkable sleeve contamination was observed.

Further, when an image was obtained under the environment of 15 ° C. and 10%, an excellent image with an initial density of 1.40 and 1.37 after copying 10,000 sheets was obtained. Even under an environment of 35 ° C and 85%, a good image with an initial density of 1.34 and 1.30 after 10,000 copies was obtained.

Comparative Example 1 A magnetic toner was obtained in the same manner as in Example 1 except that 10 parts of 3,5-di-tert.butylsalicylic acid was used instead of 5 parts of the condensate of the compound, and a copy test was conducted.

When the toner was kneaded, white smoke was generated, and sublimation of 3,5-di-tert.butylsalicylic acid was observed.

When an image was obtained in an environment of 23 ° C and 60%, the density was as low as 1.02 from the beginning, and there was no tendency to increase. Also, when the triboelectric charge amount of the toner on the developing sleeve was measured, it was -3.3
It was as low as μc / g. This is 3,5-di-te during toner manufacture.
This is because rt.butylsalicylic acid sublimated and disappeared.

Example 2 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified by a fixed wall type air classifier. The classified powder was purified.

In addition, the obtained finely divided powder is subjected to strict classification of ultrafine powder and coarse powder at the same time with a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) that utilizes the Coanda effect to produce a black powder with a volume average particle size of 11.3 μm. A fine powder was obtained.

To 100 parts of the obtained black fine powder, 0.5 part of silica fine powder hydrophobized with a silane coupling agent was added and mixed with a Henschel mixer to obtain a negatively chargeable toner. This toner was mixed with a fluorine-acryl-coated ferrite carrier having an average particle diameter of 65 μm at 10% by weight to prepare a developer.

The obtained developer is used in a commercially available color electrophotographic copier PIXEL.
(Manufactured by Canon Inc.).

When 10,000 copies were tested in an environment of 23 ° C and 60%, a clear image with an image density of 1.39 was obtained from the beginning. 1
The image after copying 0000 sheets was also clear with no fog at a density of 1.33. When the triboelectric charge amount was measured by the blow-off method, it was -14.5 µc / g in the initial stage and -13.8 µc / g after copying 10,000 sheets, showing almost no decrease.

Furthermore, when images were obtained under the environment of 15 ° C and 10%, good images were obtained with initial density of 1.38 and 1.36 after copying 10,000 sheets.
After copying 10,000 sheets with initial density of 1.35 even under the environment of 35 ° C and 85%
1.30 good images were obtained.

Comparative Example 2 Volume average particle size was the same as in Example 2 except that 3 parts of 5-chlorosalicylic acid Zn was used instead of 3 parts of the condensate of the compound.
3 μm of toner was obtained. This toner was mixed with the same fluorine-acrylic coated ferrite carrier as in Example 2 in an amount of 10% by weight to obtain a developer.

 This developer was copy tested in the same manner as in Example 2.

When a 10,000-sheet copy test was performed in an environment of 23 ° C and 60%, a good image with a density of 1.34 was obtained in the initial stage, but the image density gradually decreased, and after 10,000 sheets were copied.
It had dropped to 1.07.

Example 3 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified by a fixed wall type air classifier. The classified powder was purified.

Furthermore, the ultrafine powder and coarse powder are strictly classified at the same time with a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect to classify the obtained classified powder into a blue with a volume average particle size of 11.7 μm. A fine powder was obtained.

To 100 parts of the obtained blue fine powder, 0.5 part of silica fine powder hydrophobized with a silane coupling agent was added and mixed with a Henschel mixer to obtain a negatively chargeable toner. This toner was mixed with a fluorine-acryl-coated ferrite carrier having an average particle diameter of 65 μm at 10% by weight to prepare a developer.

The obtained developer is used in a commercially available color electrophotographic copier PIXEL.
(Manufactured by Canon Inc.).

When a copy test was performed on 10,000 sheets in an environment of 23 ° C and 60%, a bright blue image with an image density of 1.36 was obtained from the beginning. The image after copying 10,000 sheets was also clear with no fog at a density of 1.34. When the triboelectric charge amount was measured by the blow-off method, it was -13.8 µc / g in the initial stage and -13.5 µc / g after copying 10,000 sheets, and no remarkable decrease was observed.

Furthermore, when images were obtained under the conditions of 15 ° C, 10% and 35 ° C, 85%, they were as satisfactory as the images at 23 ° C, 60%.

Example 4 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified by a fixed wall type air classifier. The classified powder was purified.

Furthermore, the finely divided red and fine powder with a volume average particle diameter of 11.5 μm was obtained by strictly classifying ultrafine powder and coarse powder at the same time with a multi-division classifier (Elbowjet classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect. Got the body

To 100 parts of the obtained red fine powder, 0.5 part of silica fine powder hydrophobized with a silane coupling agent was added and mixed with a Henschel mixer to obtain a negatively chargeable toner. This toner was mixed with a fluorine-acryl-coated ferrite carrier having an average particle diameter of 65 μm at 10% by weight to prepare a developer.

The obtained developer is used in a commercially available color electrophotographic copier PIXEL.
(Manufactured by Canon Inc.).

When 10,000 copies were tested in an environment of 23 ° C and 60%, a bright magenta image with a density of 1.35 was obtained from the beginning. The image after copying 10,000 sheets was also clear without fog with a density of 1.31. Also, when the triboelectric charge amount was measured by the blow-off method, the initial value was -12.7 μc / g, 10,000
After copying one sheet, it was -12.4 µc / g, which was almost unchanged.

Furthermore, when images were obtained under the conditions of 15 ° C, 10% and 35 ° C, 85%, they were as satisfactory as the images at 23 ° C, 60%.

[Effects of the Invention] As described above, according to the present invention, a clear image can be stably obtained over a long period of time.

Claims (2)

(57) [Claims] 1. A toner for developing an electrostatic charge image, comprising a condensate of a salicylic acid having a substituent as a charge control agent. 2. A condensate of salicylic acid having at least one of an alkyl group, an amino group, a hydroxyl group, a carboxyl group, an alkoxy group, an acyl group, an aryl group and a halogen atom as a substituent is used as a charge control agent. The toner for developing an electrostatic charge image according to claim 1, wherein the toner contains the toner.