JPH07209909A - Electrostatic latent image developing toner - Google Patents

Abstract

PURPOSE:To obtain a toner high in resistance to offset and smearing by incorporating a styrene-acrylic copolymer resin, a colorant, and a specified offset preventive agent. CONSTITUTION:This toner comprises at least the styrene-acrylic copolymer resin as a binder resin, the colorant, and the offset preventive agent having a melt viscosity of 0.5-10cPs at 140 deg.C and a penetration of <=3.0dmm, and as this agent, polyeolefin wax, such as polyethylene or polypropylene waxes, alone or a combination of >=2 kinds, can be used, optionally together with any of the conventional offset preventive agents.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image developing toner for developing an electrostatic latent image formed on an image carrier.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, an electrostatic latent image is formed on the surface of an image bearing member such as a photoconductor or an electrostatic recording medium, and the latent image is developed by a toner. Form an image. This toner image is transferred from the image carrier to a transfer material such as paper and then fixed by a fixing device to form an image. As such a fixing device, a heating type fixing device such as a heat roll fixing system or a fixing system in which heat energy is applied by a heating body through a film is known.

In the toner used in such a heating type fixing device, for example, in the case of a heat roll fixing system, the toner comes into contact with the fixing roll in a heat-melted state at the time of fixing, so that the toner is used.
There is a problem of an offset phenomenon in which a part of the toner is transferred to the fixing roll and is transferred again to the next transfer material. As a technique for solving the problem of the offset phenomenon, for example, as described in JP-A-49-65232, low molecular weight polyethylene or low molecular weight polypropylene is used as an offset preventive agent together with a binder resin for toner. The technology is known. Also, JP-A-56-271
No. 56 discloses that the melt viscosity at 140 ° C. is 10 to 1
A technique for using an ethylene olefin polymer of 0 ⁶ CPS as an anti-offset agent is described. According to such a technique, the offset phenomenon can be eliminated.

However, there is a problem (smear) that the back surface of the paper is soiled when the paper having the image obtained by using the toner containing the offset preventive agent described in the above-mentioned publication is rubbed over. Will occur.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and toner for electrostatic latent image development which is excellent in offset resistance and smear resistance. The purpose is to provide −.

[0006]

According to the present invention, the styrene-acrylic copolymer resin, the colorant, and the melt viscosity at 140 ° C. are 0.5 CPS or more and less than 10 CPS and the penetration is 3.0 dmm or less. The present invention relates to a toner for developing an electrostatic latent image containing an anti-offset agent.

The inventors of the present invention have conducted intensive studies on the above-mentioned toner having improved smear resistance, and have found that this problem is caused by the offset preventive agent used for the toner. An offset preventive agent usually used for a toner has a melt viscosity of 10 to 10 ⁶ CPS.
Since the penetrating degree is about 1 to 7, the viscosity is high and the bleeding time of the offset preventive agent at the time of fixing is delayed, and the thinning of the offset preventive agent on the toner surface layer becomes uneven, resulting in a smear problem. Is thought to occur.

The inventors have found that the smear resistance can be improved by using an ethylene-based olefin polymer having a low viscosity and a high hardness as the offset preventing agent to be used, and thus the present invention has been accomplished.

The toner of the present invention uses a styrene-acrylic copolymer resin as a binder resin.

Monomers that can be used to obtain a styrene-acrylic copolymer resin include, for example, styrene and
o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-octylstyrene, pn- Styrenes such as dodecyl styrene, p-phenyl styrene and 3,4-dichlorostyrene and their derivatives, ethylene,
Ethylenically unsaturated monoolefins such as propylene and butylene, vinyl halides such as vinyl chloride, vinylidene chloride and vinyl bromide, vinyl acetate, vinyl propionate, vinyl naphthalene, vinyl benzoate and other vinyl esters, acrylic acid Methyl, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, phenyl acrylate, methyl methacrylate , Ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, methacryl Stearyl, phenyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylic acid,
Α-Methylene aliphatic monocarboxylic acid esters such as methacrylic acid, (meth) acrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether, vinyl Vinyl ketones such as methyl ketone and N-vinyl compounds such as N-vinylpyrrole and N-vinylcarbazol can be used.

In the above binder resin,
The number average molecular weight Mn is 1000 ≦ Mn ≦ 10000, preferably 2000 ≦ Mn ≦ 7000, and the weight average molecular weight Mw and the number average molecular weight Mn are 20 ≦ Mw / Mn ≦ 70.
It is preferable to use the following from the viewpoint of fixability.

The offset preventive agent used in the toner of the present invention has a melt viscosity at 140 ° C. of 0.5 CPS.
Or more and less than 10 CPS, preferably 3.0 CPS or more 9.
A material having a 0 CPS or less and a penetration of 3.0 dmm or less, preferably 0.1 to 2.0 dmm is used. When the melt viscosity is less than 0.5 CPS, the viscosity becomes low and the offset preventive agent is easily melted at a low temperature, so that the fluidity and heat resistance of the toner are likely to be deteriorated. Also, 10 CP
If it is S or more, the viscosity becomes high and the exudation of the offset preventive agent at the time of fixing becomes poor, so that it becomes difficult to form a uniform film of the offset preventive agent on the toner surface, and the smear resistance deteriorates. . Further, if the penetration is larger than 3.0 dmm, the offset preventive agent is soft, so that the offset preventive agent present on the toner surface after fixing is vulnerable to rubbing of the paper and easily peeled off.

As the offset preventive agent, ethylene-based polyolefin polymer waxes such as polyethylene wax and polypropylene wax can be used alone or in admixture of two or more kinds.

The anti-offset agent may be added in an amount of 0.5 to 10 parts by weight, preferably 1 to 2.5 parts by weight, based on 100 parts by weight of the binder resin of the toner. From the viewpoint of.

Further, the above-mentioned offset preventive agent of the present invention may be used in combination with a commonly used offset preventive agent. As such an offset preventive agent, the above-mentioned ethylene-based polyolefin polymer wax having a melt viscosity of 10 to 10 ⁶ CPS, higher fatty acid wax, higher fatty acid ester wax, sazol wax, candelilla wax, carnauba wax, etc. Can be used. The amount thereof used is in the range of 1.0 to 10 parts by weight, preferably 1.0 to 4.0 parts by weight, based on 100 parts by weight of the binder resin of the toner. It is preferable to use them as described above, and the effect of improving the high temperature offset region can be obtained by using the anti-offset agent together.

A charge control agent, magnetic powder, etc. may be added to the toner according to the present invention, if necessary.

For example, as the positive charge control agent, an azine compound nigrosine base EX, Bontron N-01, 0
2, 04, 05, 07, 09, 10, 13 (manufactured by Orient Chemical Industry Co., Ltd.), oil black (manufactured by Chuo Synthetic Chemical Industry Co., Ltd.), quaternary ammonium salt P-51, polyamine compound P-52, sudanchi- Fuschwartz BB (Solvent Black 3: CI No. 26150), Fett Schwartz HBN (CI No. 26150), Brilliant Spirits Schwarz TN (manufactured by Farben Fabriken Bayer), and an alkoxylated amine,
Alkyl amides, molybdic acid chelate pigments, imidazole compounds and the like can be used.

Examples of the negative charge control agent include chromium complex salt type azo dyes S-32, 33, 34, 35, 37 and 3.
8, 40 (manufactured by Orient Chemical Industry Co., Ltd.), Eisenspirone Black TRH, BHH (manufactured by Hodogaya Chemical Co., Ltd.), Kayaset Black T-22,004 (manufactured by Nippon Kayaku Co., Ltd.), copper phthalocyanine dye S-39 ( Orient Chemical Co., Ltd.), chromium complex salts E-81, 82 (Orient Chemical Co., Ltd.), zinc complex salt E-84 (Orient Chemical Co., Ltd.), aluminum complex salt E-86 (Orient Chemical Co., Ltd.), Calix Allene A system compound etc. can be used.

As the magnetic powder, for example, cobalt, iron,
Ferromagnetic metals such as nickel, cobalt, iron, nickel, aluminum, lead, magnesium, zinc, antimony, beryllium, bismuth, cadmium, calcium,
It is possible to use alloys of metals such as manganese, selenium, titanium, tungsten, vanadium, mixtures of these metals, and fine particles of known magnetic materials such as oxides and fired bodies (ferrite).

Further, the toner according to the present invention may be treated by adding a fluidizing agent to the surface thereof. The addition of the fluidizing agent can be performed by mechanically mixing the toner and the fluidizing agent. Examples of the fluidizing agent include silica particles, titanium dioxide particles, alumina particles, magnesium fluoride particles, silicon carbide particles, boron carbide particles, titanium carbide particles, zirconium carbide particles, boron nitride particles, titanium nitride particles, zirconium nitride particles, magnetite. Fine particles, molybdenum disulfide fine particles,
Aluminum stearate fine particles, magnesium stearate fine particles, zinc stearate fine particles, fluororesin fine particles, acrylic resin fine particles and the like can be used alone or in combination of two or more kinds. The amount of the fluidizing agent added is 0.05 to 2% by weight, preferably 0.1 to 2% by weight, based on the toner.
It is 1% by weight. By using such an addition amount, the fluidity can be improved without impairing the environmental stability of the developer. Further, as the fluidizing agent, it is preferable to use one that has been subjected to a hydrophobic treatment from the viewpoint of improving environmental stability, and as the hydrophobicizing agent, a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, etc. Can be used.

[0021]

EXAMPLES The present invention will be described below with reference to examples, but the invention is not limited thereto.

(Production Example of Toner-A) Styrene-butyl acrylate-butyl methacrylate-methacrylic acid copolymer having a molecular weight of 5000 in GPC chromatogram (monomer-weight ratio 7: 1.4: 1) .4: 0.2) 35 parts by weight Styrene-butyl acrylate-butyl methacrylate-methacrylic acid copolymer having a molecular weight of 200,000 in GPC chromatogram (monomer weight ratio 6: 1.9: 1.9: 0.2) 65 parts by weight-Positive charge control agent (nigrosine dye) (Nigrosine base EX: manufactured by Orient Chemical Industry Co., Ltd.) 5 parts by weight-Offset inhibitor (low molecular weight polyethylene) 3 parts by weight (140 ° C) Melt viscosity in: 8.5 CPS, penetration: 0.4 dmm) Colorant (Mogar L: made by Cabot) 7 parts by weight or more A Henschel mixer - with sufficiently mixed, melted and kneaded by a biaxial extrusion kneader, cooled and then subjected to fine grinding according to a coarse grinding and jet mill, toner having an average particle size of 10μm was classified - to obtain particles.

To 100 parts by weight of the toner particles, 0.2 parts by weight of hydrophobic silica fine powder (R974: manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain Toner A.

(Production Example of Tona-B) In the production example of Tona-A, except that 5 parts by weight of low molecular weight polypropylene (melt viscosity at 140 ° C .: 2500 CPS, penetration: 2.7 dmm) was used as an offset inhibitor. Similarly, Toner-B was obtained.

(Production Example of Tona-C) In the production example of Tona-A, a low molecular weight polypropylene (melt viscosity at 140 ° C .: 5.0 CPS, penetration:
Toner-C was obtained in the same manner except that 3.5 parts by weight of 8.0 dmm) was used.

(Production Example of Tona-D) In the production example of Tona-A, a low molecular weight polyethylene (melt viscosity at 140 ° C .: 7.0 CPS, penetration:
Toner-D was obtained in the same manner except that 4 parts by weight of 1.1 dmm) was used.

(Production Example of Tona-E) In the production example of Tona-A, low-molecular-weight polyethylene (melt viscosity at 140 ° C .: 2.9 CPS, penetration:
Toner-E was obtained in the same manner except that 3.5 parts by weight of 1.9 dmm) was used.

(Production Example of Tona-F) In the production example of Tona-A, low molecular weight polyethylene (melt viscosity at 140 ° C .: 5.5 CPS, penetration:
Toner-F was obtained in the same manner except that 4 parts by weight of 2.8 dmm) was used.

(Production Example of Tona-G) In the production example of Tona-A, low molecular weight polyethylene (melt viscosity at 140 ° C .: 8.5 CPS, penetration:
Toner-G was obtained in the same manner except that 2.5 parts by weight of 0.4 dmm) and 1 part by weight of low molecular weight polypropylene (melt viscosity at 140 ° C .: 2500 CPS, penetration: 2.7 dmm) were used. (Carrier production example) Polyester resin 100 parts by weight (Mn: 5000, Mw: 115000, Tg: 67 ° C, Tm: 123 ° C) Ferrite fine particles 500 parts by weight (MFP-2, manufactured by TDK) Dispersant colloidal silica 3 parts by weight (Aerosil # 200, manufactured by Nippon Aerosil Co., Ltd.) After thoroughly mixing the above materials with a Henschel mixer, melt-kneading with a twin-screw extrusion kneader, cooling, coarse pulverization, fine pulverization with a jet mill, and wind Classifying with a classifier, average particle size 60 μm, electric resistance value 5.8 × 10 ¹³ Ω
I got a cm carrier.

Examples and Comparative Examples The toners A to G obtained in the above toner production examples and the carriers obtained in the carrier production examples were combined as shown in Table 1 in a weight ratio of 1:20. And the developer of the comparative example was obtained.

The resulting developer was imaged using a copying machine EP9765 (manufactured by Minolta Camera Co.), and the following items were evaluated. The results are shown in Table 1. The white offset and smear resistance were initially evaluated, and the fog and toner replenishment properties were evaluated after printing 100,000 sheets.

(White Offset) The white offset was judged by carrying out image formation using a sheet for exclusive use of OHP and visually observing stains on the sheet portion. The sheet was evaluated as ⊚ when it was in a completely transparent state, as ◯ when there was some offset but no practical problem, and as × when practical problem.

(Smear resistance) Regarding smear resistance, a smear evaluation tester (MRT-1 type: manufactured by Minolta Camera Co., Ltd.)
Using, the toner remaining on the back surface of the paper when the two sheets of the image-formed and laminated paper and the paper were rubbed together was visually determined. The toner with no toner remaining on the back side of the paper is very excellent in smear resistance ◎, the one with a slight smear but no practical problem ○, the smear is generated and there is a practical problem The thing was evaluated as x.

(Fog) Regarding the fog on the image, the toner fog on the white background portion of the image was visually determined. A sample having no fog and being very excellent was evaluated as ⊚, a sample having fog but having no practical problem was evaluated as ◯, and a sample having a large amount of fog and having a practical problem was evaluated as x.

(Toner replenishing property) Regarding the toner replenishing property, the state of powder property of the toner was measured by using a powder tester (manufactured by Hosokawa Micron Co., Ltd.), and the loose apparent specific gravity was 0.400 to 0. 420, those having a repose angle of 35 ° or less are ◎, loose apparent specific gravity is 0.380 to 0.400, and repose angles are 35 to 40 ° are ○, loose apparent specific gravity is 0.380 or less, and repose angle is 40 Those above ° were evaluated as x.

[0036]

[Table 1]

[0037]

According to the present invention, it is possible to provide a toner excellent in offset resistance and smear resistance.

[0038]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Fukao 2-3-13 Azuchi-cho, Chuo-ku, Osaka City Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Hiroyuki Fukuda 2-chome, Azuchi-cho, Chuo-ku, Osaka No. 13 Osaka International Building Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. A styrene-acrylic copolymer resin, a colorant, and an offset preventive agent having a melt viscosity at 140 ° C. of 0.5 CPS or more and less than 10 CPS and a penetration of 3.0 dmm or less. A toner for developing electrostatic latent images.