JPH0934174A - Electrostatic charge image developing toner, its production and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good fixing property and blocking resistance by using a polyester resin as the main component, incorporating a specified acid carbon black and controlling the dielectric loss tangent to a specified value. SOLUTION: This toner consists of a binder resin, coloring agent and release agent. The binder resin essentially consists of a polyester resin, and the coloring agent contains an acid carbon black of pH<7. The dielectric loss tangent of the toner is <=25. As for the polyester resin, a resin produced from a polyvalent hydroxy compd. and polyvalent carboxylic acids or reactive deriv. of these such as lower alkyl esters, acid anhydrides, and acid halides can be used. As for the release agent, polyolefin such as a low mol.wt. polyethylene and low mol.wt. polypropylene, or natural wax such as paraffin wax, carnauba maw, montan wax, and candelilla wax or deriv. of these can be used. Further, water is added when the source material mixture containing a binder resin, coloring agent and release agent is kneaded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developing toner for developing an electrostatic latent image, a method for producing the same, and an image forming method.

[0002]

2. Description of the Related Art In electrophotography, a two-component developing system consisting of toner and carrier and a one-component developing system containing a magnetic material are known as a method for visualizing an electric latent image. In the above, the two-component developing method is predominant. Further, for energy saving and high-speed suitability, a toner having a lower temperature fixing property is required, but in the contact heating fixing method, offset to a heat roll is likely to occur, and it is a problem to achieve both low temperature fixing property and offset resistance. ing.

In order to achieve the above object, it is proposed to use a resin having a maximum value in a region having a low molecular weight and a resin having a high molecular weight as a binder resin (for example, JP-A-56-161).
No. 44) and various proposals using a crystalline polyester resin having a sharp melt property. However, in a fixing system which does not use an offset preventing liquid,
It is essential to include a release agent such as wax in the toner. However, when a binder resin, particularly a polyester resin, contains a release agent, the problem of toner blocking during storage, and in-machine contamination related to the maintainability of charge,
The actual situation is that there is a problem in maintaining the image quality, and there is no toner composition that is sufficiently satisfactory.

[0004]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above problems. That is, the object of the present invention is to provide a wide fixing temperature range in the contact heating fixing method (width between the minimum fixing temperature for obtaining a satisfactory fixing degree and the maximum temperature at which offset does not occur).
(EN) A toner for developing an electrostatic charge image, which does not cause blocking or the like during storage, and a developer composition using the toner. Another object of the present invention is to provide a toner for developing an electrostatic charge image, which is excellent in the maintainability of charge and the maintainability of image quality even during continuous copying for a long period of time and does not cause problems such as stains inside the machine. Still another object of the present invention is to provide an electrostatic charge image developing toner in which the toner is not transferred to the vinyl chloride sheet even when the toner fixed image and the vinyl chloride sheet are stored in close contact with each other. Another object of the present invention is to provide a method for producing the above electrostatic charge image developing toner. Still another object of the present invention is to provide an image forming method using the above electrostatic toner image developing toner.

[0005]

Means for Solving the Problems The inventors of the present invention have completed the present invention as a result of earnest studies on means for achieving the above object.

That is, the toner for developing an electrostatic charge image of the present invention comprises a binder resin, a coloring material and a releasing agent, the binder resin containing a polyester resin as a main component, and the coloring material having a pH of 7
The content of the acidic carbon black is less than 25, and the dielectric loss tangent value of the toner is 25 or less. The electrostatic image developer composition of the present invention is characterized by comprising the above electrostatic image developing toner and a resin-coated carrier. Also,
The method for producing the toner for developing an electrostatic image of the present invention uses a resin having a polyester resin as a main component as a binder resin, acidic carbon black having a pH of less than 7 as a coloring material, and a binder resin and a colorant. Water is added during the kneading of the raw material mixture containing the material and the release agent.

Further, in the image forming method of the present invention, the step of forming an electrostatic latent image on the image bearing member, the step of developing the electrostatic latent image with the developer on the developer bearing member, the image The method has a step of transferring a toner image formed on a carrier to a transfer body, wherein a binder resin contains a polyester resin as a main component and an acidic carbon black having a pH of less than 7 is used as a developer. It is characterized by using a toner containing an electrostatic charge image developing toner having a dielectric loss tangent value of 25 or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The binder resin in the toner for developing an electrostatic image of the present invention contains a polyester resin as a main component, and as the polyester resin, a polyvalent hydroxy compound and a polyvalent carboxylic acid or a lower alkyl ester thereof, an acid anhydride is used. And a reactive derivative such as an acid halide.

Examples of polyhydric hydroxy compounds are ethylene glycol, propylene glycol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1 , Polyethylene glycol such as 4-cyclohexanedimethanol, diethylene glycol and triethylene glycol, polypropylene glycol such as dipropylene glycol and tripropylene glycol, bisphenol A and its derivatives, alkylene oxide adducts thereof, and divalent hydroxy such as hydrogenated bisphenol A Examples thereof include compounds, and in addition, trivalent or higher hydroxy compounds such as glycerin, sorbitol, and trimethylolpropane can be used.

Examples of the polycarboxylic acid include malonic acid, succinic acid, glutaric acid, 1,2,5-hexanetricarboxylic acid, 1,2,7,8-octanetetracarboxylic acid, and n-octylsuccinic acid. , Tetra (carboxylmethyl) methane, maleic acid, fumaric acid, dodecenylsuccinic acid, 1,2,4-cyclohexanetricarboxylic acid,
Phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, 1,2,4-naphthalenetricarboxylic acid and the like can be used.

The coloring material in the present invention needs to contain acidic carbon black, but other colorants such as aniline blue, calcyl blue, and pigment blue 15: 3 may be used together for the purpose of adjusting the color tone. May be. The acidic carbon black is contained in the toner in an amount of 4 to 15% by weight, particularly 6 to
It is preferable to add 12% by weight. 4% by weight
If it is less than the above, it is difficult to obtain the desired image density, and if it exceeds 15% by weight, the desired charge amount cannot be obtained. Further, the carbon black used in the present invention is acidic carbon black, and it is necessary that the pH is less than 7. It is presumed that such acidic carbon black works effectively to help the toner to be negatively charged. The pH of carbon black is a value measured by using a water slurry of carbon black and using a pH meter having a glass electrode.

As the releasing agent in the present invention, polyolefins represented by low molecular weight polyethylene and low molecular weight polypropylene, natural waxes such as paraffin wax, carnauba wax, montan wax and candelilla wax and derivatives thereof can be used. The amount is
It is preferably in the range of 3 to 10% by weight in the toner. If the blending amount is less than 3% by weight, the desired offset resistance cannot be obtained, and if the blending amount exceeds 10% by weight, not only the fluidity of the toner is impaired but also the maintainability of charging is deteriorated.

Various substances can be added to the toner for developing an electrostatic image of the present invention for the purpose of charge control, electric resistance control and the like. For example, a fluorine-based surfactant, a metal complex of salicylic acid, a chromium dye, or a charge control resin such as a copolymer containing maleic acid or carboxylic acid of acrylic acid as a monomer component can be added. Also,
A small amount of magnetic powder may be contained in the toner for the purpose of preventing stains inside the apparatus.

Furthermore, a copolymer of styrene and acrylic, an epoxy resin or the like may be blended with the binder resin to the extent that the fixability is not impaired.

The electrostatic development toner of the present invention must have a dielectric loss tangent value of 25 or less. When the value of the dielectric loss tangent is 25 or less, the release agent can be uniformly dispersed in the polyester resin. When the value of the dielectric loss tangent of the toner is larger than 25, it becomes difficult to disperse the release agent in the polyester resin, the release agent is unevenly dispersed, and the toner having different charging ability is mixed. As a result, when toner is added during continuous copying, the charge distribution width is widened or toner of opposite polarity is generated, which appears as a phenomenon such as in-machine contamination or contamination of the background portion of image quality.

The toner for developing an electrostatic image of the present invention can be produced by kneading and pulverizing the above-mentioned raw material components, but it is necessary to add water at the time of kneading the raw material mixture. This makes it possible to manufacture a toner for developing an electrostatic charge image having a dielectric loss tangent value of 25 or less. The amount of water added during kneading is based on the raw material mixture to be kneaded.
The range of 5 to 15% by weight is preferred. In addition, the particle size of the toner is generally preferably in the range of 5 to 15 μm.

The toner for developing an electrostatic charge image of the present invention comprises:
To improve the fluidity of the toner, SiO ₂ , Ti
O ₂ , Al ₂ O ₃ , ZnO, CeO ₂ , CaCO ₃ , Z
Fine particles of inorganic compounds such as rO ₂ and MgO may be added externally, or cleaning aids or transfer aids such as silicone resin, polystyrene fine particles, polymethylmethacrylate fine particles, polyvinylidene fluoride fine particles, etc. for the purpose of improving the cleaning property. May be added externally. In particular, hydrophobic silica having a primary particle size of 5 nm to 30 nm is preferably used.

The toner for an electrostatic image developer obtained as described above can be used as a one-component developer or a two-component developer. When used as a two-component developer, a toner for an electrostatic image developer may be mixed with a carrier before use. Examples of the carrier include ferrite, iron oxide powder, nickel, a resin-coated carrier obtained by coating these with a resin, and a magnetic powder-dispersed carrier.
In the present invention, a resin-coated carrier is particularly preferably used in terms of durability. As the coating resin, a fluorine resin, a silicone resin, a styrene resin, an acrylic resin, or an amide resin can be used. The average particle size of the carrier is preferably in the range of 20 to 150 μm. In the developer composition for an electrostatic charge image of the present invention, the compounding ratio of the toner for an electrostatic charge image developer and the carrier is preferably in the range of 3 to 10% by weight as a toner concentration.

Next, the image forming method of the present invention will be described. The image forming method of the present invention comprises a step of forming an electrostatic latent image on an image bearing member such as an electrophotographic photosensitive member or an electrostatic recording member, using the developer on the developer bearing member to form the electrostatic latent image. The developing step and the step of transferring the toner image formed on the image carrier onto the transfer body. As the electrophotographic photosensitive member, a Se-based photosensitive member, an organic photosensitive member, an amorphous silicon-based photosensitive member,
Alternatively, conventionally known ones such as those whose surface is overcoated if necessary can be used. An electrostatic latent image is formed on the image carrier by a known method,
Then, the toner is developed with the above-mentioned toner for developing an electrostatic image in the present invention, and a toner image is formed on the image carrier. The formed toner image is transferred onto a transfer body such as paper by a conventional method, and the toner remaining on the image carrier is cleaned by a cleaning unit. As the cleaning means, any conventionally known means can be used.

[0020]

The effect of the improving effect of the toner for developing an electrostatic image of the present invention is not clear, but it is presumed as follows. When a polyester resin is used as the binder resin, it is difficult to disperse the release agent therein,
The release agent is unevenly dispersed, and as a result, toners having different charging capabilities are mixed. The dispersibility of the release agent is closely related to the value of the dielectric loss tangent of the toner, and when the value is 25 or less, the release agent is uniformly dispersed in the polyester resin. In addition, as carbon black for the coloring material, acidic carbon black is considered to work effectively because it assists in negative charging. The value of the dielectric loss tangent of the toner serves as an index not only for the dispersion of the release agent but also for the dispersion of the carbon black. When the value is 25 or less, the dispersion of the carbon black and the release agent The dispersion interacts with the desired result. That is, when toner is added during continuous copying, the charge distribution width is not widened and the opposite polarity toner is not generated, and the occurrence of stains inside the apparatus and background stains of image quality is prevented.

[0021]

EXAMPLES The present invention will be described in more detail below with reference to examples. However, the present invention is in no way limited by these examples. Production Example 1 (Polyester resin A) Bisphenol A-ethylene oxide 2 adduct 30 mol Bisphenol A-propylene oxide 2 adduct 20 mol Terephthalic acid 30 mol Fumaric acid 20 mol Stainless steel stirrer, glass nitrogen gas inlet pipe and downflow The flask was placed in a four-necked round bottom flask equipped with a formula condenser, and heated with a mantle heater while introducing nitrogen gas. Then, the temperature of the reaction product was kept at 200 ° C., and the reaction was carried out for 6 hours while distilling off the produced water. The obtained polyester resin has a weight average molecular weight Mw of about 1
4,000, number average molecular weight Mn = about 4,000, Tg =
It was 61.5 ° C.

Production Example 2 (Polyester Resin B) Bisphenol A-Ethylene oxide 2 adduct 18 mol Bisphenol A-Propylene oxide 2 adduct 18 mol Terephthalic acid 4 mol Succinic acid derivative 7 mol Trimellitic anhydride 25 mol A polyester resin containing 30% of gel was obtained in the same manner as in Production Example 1 except that the polyester resin was used. (Tg = 64
℃)

Toner Production Example 1 20 parts by weight of the polyester resin A 80 parts by weight of the polyester resin B 10 parts by weight of carbon black 10 parts by weight of carbon black (BP-1300, Cabot Corporation, pH 2.5) 6 parts by weight of low molecular weight polypropylene (Viscole 660P, 2% of water was added to the above components and kneaded with a continuous mixer. After rolling and cooling, coarse pulverization was performed using a hammer mill, fine pulverization was performed using a jet mill, and classification was performed to obtain toner particles having a volume average particle diameter D50 of 9 μm. After 5 g of the toner particles were weighed and molded with a pressure molding machine (made by Maekawa Testing Machine Co., Ltd.), the dielectric loss tangent was measured by a dielectric constant measuring device (YHP LCR meter 4274A), and the value was 18. . The toner particles 10
0.5 part by weight of hydrophobic silica (R-972, manufactured by Nippon Aerosil Co., Ltd.) was added to 0 part by weight, and the mixture was dispersed and mixed using a Henschel mixer to prepare a toner having silica fine particles attached to the surface thereof.

Toner Production Example 2 In the toner production example 1, carbon black (BP-
1300, manufactured by Cabot Co., Ltd.) was used, and a toner was obtained in exactly the same manner except that water was added at 1% during kneading. Its dielectric loss tangent value was 15. Toner Production Example 3 A toner was obtained in exactly the same manner as in Toner Production Example 1 except that water was not added during kneading. Its dielectric loss tangent value was 29. Toner Production Example 4 In the toner production example 1, carbon black (BP-
1300, made by Cabot Co., is carbon black (R-
A toner was obtained in exactly the same manner except that 330, pH 8) manufactured by Cabot Corporation was used. The dielectric loss tangent value was 10.

Preparation of Developer As a carrier, a carrier obtained by coating ferrite particles having an average particle size of 80 μm with an acrylic resin was used. Further, the toner prepared in the above production example was used as the toner, and these were mixed with a V blender so that the toner concentration becomes 4 to 6% to obtain a developer.

Evaluation was carried out by the following evaluation method using the above developer. Table 1 shows the results. (Continuous copying test) Prepared developer
10 using a reversing remodeling machine of 500 (Fuji Xerox)
A continuous copy test was performed on 10,000 sheets to evaluate the copy density, the fog on the photoconductor (fog on the photosensitive material), the fog on the copied image (fog on the copy), and the in-machine stain. The symbols in Table 1 mean the following. A: Copy density, B: Fog on photosensitive material, C: Fog on copy, D: Stain inside machine. Copy density: measured with a Macbeth densitometer Fog on photosensitive material, fog on copy: G1 (good) to G5
Judged by comparing with the limit sample up to (bad) In-machine dirt: visually determined from G1 (good) to G5 (bad)

[0027]

[Table 1]

[0028]

EFFECT OF THE INVENTION The toner for developing an electrostatic image of the present invention is excellent in fixing property and blocking resistance, and particularly excellent in maintaining charge and maintaining image quality. Further, fogging on the photoconductor and contamination in the machine will not occur. Therefore, by using this electrostatic charge image developing toner or the electrostatic charge image developer composition containing the same, a copied image having an excellent image density without fogging can be produced for a long period of time.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 9/08 381 9/10 351 (72) Inventor Jun Igarashi 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Zero (72) Inventor Yusaku Shibuya 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (72) Koichi Hamano 1600 Takematsu, Minamiashigara, Kanagawa Prefecture (72) Inventor Usami Masaaki 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (6)

[Claims] 1. An electrostatic charge image developing toner comprising a binder resin, a coloring material and a release agent, wherein the binder resin contains a polyester resin as a main component, and the coloring material has a pH of less than 7 And the dielectric loss tangent value of the toner is 2
A toner for developing an electrostatic charge image, which is 5 or less. 2. The toner for developing an electrostatic charge image according to claim 1, wherein the release agent is a polyolefin. 3. The release agent is 3 to 10% by weight based on the toner.
The toner for developing an electrostatic charge image according to claim 1, wherein the toner contains the toner. 4. An electrostatic charge image developing composition comprising a carrier for electrostatic charge image development containing a binder resin, a coloring material and a release agent, and a carrier, wherein the toner for developing electrostatic charge image is a binder resin. Polyester resin as the main component and p as the coloring material
An electrostatic charge image developer composition containing an acidic carbon black of less than H7, wherein the toner has a dielectric loss tangent value of 25 or less, and the carrier is a resin-coated carrier. 5. A method for producing a toner for developing an electrostatic charge image, which comprises kneading and pulverizing a raw material mixture containing a binder resin, a coloring material and a releasing agent, and a polyester resin as a main component of the binder resin. Using a resin that
A method for producing an electrostatic charge image developing toner having a dielectric loss tangent value of 25 or less, characterized by using acidic carbon black of less than 7 and adding water during kneading of the raw material mixture. 6. A step of forming an electrostatic latent image on an image carrier,
An image forming method comprising: a step of developing the electrostatic latent image using a developer on a developer carrying member; and a step of transferring a toner image formed on the image carrying member onto a transfer member, wherein the developer As the binder resin, a binder resin containing a polyester resin as a main component, the coloring material containing acidic carbon black having a pH of less than 7 and an electrostatic image developing toner having a dielectric loss tangent value of 25 or less is used. An image forming method characterized by the above.