JP3230360B2 - Toner for developing electrostatic latent images - Google Patents

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 carrier such as a photoreceptor or an electrostatic recording medium, and the latent image is developed by a toner. Form an image. The 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 method or a fixing method in which heat energy is applied by a heating element via a film is known.

The toner used in such a heating type fixing device is, for example, in the case of a hot roll fixing method, the toner contacts the fixing roll in a hot melt state at the time of fixing.
Is partially transferred to the fixing roll and then transferred to the next transfer material again, which causes an offset phenomenon. As a technique for solving the problem of the offset phenomenon, for example, as described in JP-A-49-65232, a low molecular weight polyethylene or a low molecular weight polypropylene is used as an offset preventing agent together with a toner binder resin. The technology is known. Also, Japanese Patent Application Laid-Open No. 56-271
No. 56 discloses that the melt viscosity at 140 ° C. is 10-1.
0 ⁶ techniques using ethylene olefin polymer CPS as an offset preventing agent. According to such a technique, it is possible to eliminate the offset phenomenon.

[0004] However, there is a problem (smearing) that when the paper having an image obtained by using the toner containing the offset preventing agent described in the above-mentioned publication is overlapped and rubbed, the back surface of the paper is stained (smear). Will happen.

[0005]

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

[0006]

According to the present invention, a styrene-acrylic copolymer resin, a colorant and a melt viscosity at 140 ° C. of 0.5 to less than 10 CPS and a penetration of 3.0 dmm or less. The present invention relates to an electrostatic latent image developing toner containing a polyethylene wax .

The present inventors have conducted intensive studies on the above-mentioned toner having improved smear resistance and found that this problem is caused by the offset preventing agent used in the toner. An offset preventing agent usually used for toner has a melt viscosity of 10 to 10 ⁶ CPS.
And the penetration is about 1 to 7, the viscosity is so high that the timing of exudation of the offset preventing agent at the time of fixing is delayed, and the thinning of the offset preventing agent on the toner surface layer causes unevenness, which causes a problem of smear. Is considered to occur.

The present invention has been found that smear resistance can be improved by using a polyethylene wax having a low viscosity and a high hardness as an offset preventing agent to be used.

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

Examples of monomers that can be used to obtain the styrene-acrylic copolymer resin include, for example, styrene,
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, 3,4-dichlorostyrene and derivatives thereof, ethylene,
Ethylene unsaturated monoolefins such as propylene and butylene, vinyl halides such as vinyl chloride, vinylidene chloride and vinyl bromide, vinyl esters such as vinyl acetate, vinyl propionate, vinyl naphthalene and vinyl benzoate, and 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-vinylpyrrol and N-vinylcarbazole can be used.

[0011] 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 desirable from the viewpoint of fixability to use those having the following.

Polyethylene used in the toner of the present invention
The box, 0.5 C melt viscosity at 140 ° C.
A material having a PS of 10 CPS or more and less than 10 CPS, preferably 3.0 CPS or more and 9.0 CPS or less, and a penetration of 3.0 dmm or less, preferably 0.1 to 2.0 dmm is used. If the melt viscosity is less than 0.5 CPS, the viscosity becomes low and the polyethylene wax is easily melted at a low temperature, so that the fluidity and heat resistance of the toner are liable to decrease. On the other hand, if the viscosity is higher than 10 CPS, the viscosity becomes high, so that the exudation of the polyethylene wax at the time of fixing becomes worse, and it becomes difficult to form a uniform film of the polyethylene wax on the toner surface, so that the smear resistance decreases. . Also, penetration after fixing 3.0dmm larger than for polyethylene wax <br/> soft toner - present on the surface polyethylene
Problem Ren wax is easily peeled off vulnerable to rubbing of the paper occurs.

[0013]

The polyethylene wax is used in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the binder resin of the toner.
Preferably added in the range of 1 to 2.5 parts by weight,
It is preferable from the viewpoint of offset resistance and smear resistance.

Further, the polyethylene wax according to the present invention may be used in combination with a commonly used offset preventing agent. Such offset inhibitor, polyethylene wax, <br/> melt viscosity at 140 ° C. in ethylene-based polyolefin polymer wax polypropylene wax 10 to 10 of 6 ^CPS ones, higher fatty acid wax, higher fatty acid ester waxes, Sasol wax, candelilla wax, carnauba wax and the like can be used. The amount used is the amount combined with the polyethylene wax according to the present invention.
1.0 to 10 parts by weight, preferably 1.10 parts by weight, based on 0 parts by weight.
It is preferable to use it in the range of 0 to 4.0 parts by weight, and the effect of improving the high-temperature offset region can be obtained by using the offset preventing agent in combination.

The toner according to the present invention may be added with a charge control agent, a magnetic powder and the like, if necessary.

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

Examples of the negative charge control agent include chromium complex type azo dyes S-32, 33, 34, 35, 37, 3
8, 40 (manufactured by Orient Chemical Co., Ltd.), Aizen Spiron 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 Industry Co., Ltd.), Chromium Complex Salts E-81, 82 (Orient Chemical Industry Co., Ltd.), Zinc Complex Salt E-84 (Orient Chemical Industry Co., Ltd.), Aluminum Complex Salt E-86 (Orient Chemical Industry Co., Ltd.), Calix Allen System compounds and the like 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,
Alloys of metals such as manganese, selenium, titanium, tungsten, and vanadium, and mixtures of these metals, and fine particles of known magnetic substances such as oxides and fired bodies (ferrites) can be used.

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

[0021]

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

(Production Example of Toner-A) Styrene-butyl acrylate-butyl methacrylate-methacrylic acid copolymer having a peak at a molecular weight of 5000 in a GPC chromatogram (monomer-weight ratio: 7: 1.4: 1) .4: 0.2) 35 parts by weight A styrene-butyl acrylate-butyl methacrylate-methacrylic acid copolymer having a peak at a molecular weight of 200,000 in a 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 Industries) 5 parts by weight ・ Offset inhibitor (low molecular weight polyethylene) 3 parts by weight (140 ° C.) Melt viscosity: 8.5 CPS, penetration: 0.4 dmm) Colorant (Mogal L: manufactured 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 part by weight of a hydrophobic silica fine powder (R974: manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain toner A.

(Production Example of Toner-B) Except for using 5 parts by weight of low molecular weight polypropylene (melt viscosity at 140 ° C .: 2500 CPS, penetration: 2.7 dmm) as an anti-offset agent in the production example of Toner-A Similarly, toner B was obtained.

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

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

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

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

(Production Example of Toner-G) In the production example of Toner-A, 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. (Example of carrier production) 100 parts by weight of polyester resin (Mn: 5000, Mw: 115000, Tg: 67 ° C., Tm: 123 ° C.) 500 parts by weight of ferrite fine particles (MFP-2, manufactured by TDK) 3 parts by weight colloidal silica (Aerosil # 200, manufactured by Nippon Aerosil Co., Ltd.) After sufficiently mixing the above materials with a Henschel mixer, melting and kneading with a twin screw extruder, cooling, coarsely pulverizing, finely pulverizing with a jet mill, The particles were classified using a classifier and had an average particle size of 60 μm and an electric resistance value of 5.8 × 10 ¹³ Ω.
Cm carrier was obtained.

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 in a weight ratio of 1:20 as shown in Table 1 to obtain examples. And the developer of the comparative example was obtained.

An image of the obtained developer was formed using a copying machine EP9765 (manufactured by Minolta Camera Co., Ltd.), and the following items were evaluated. The results are shown in Table 1. The white offset and the smear resistance were evaluated at the initial stage, and the fog and toner replenishment were evaluated after 100,000 sheets were printed.

(White Offset) The white offset was determined by performing image output using an OHP-dedicated sheet and visually observing the dirt on the sheet portion. The sheet which was in a completely transparent state was evaluated as オ フ セ ッ ト, the one having a slight offset but having no practical problem was evaluated as ○, and the one having practical problem was evaluated as ×.

(Smear Resistance) The smear resistance was evaluated by using a smear evaluation tester (MRT-1: manufactured by Minolta Camera Co., Ltd.).
The toner remaining on the back side of the paper when the two sheets of paper on which an image was formed and laminated were rubbed with each other was visually determined. ◎: very good smear resistance without toner remaining on the back side of the paper; ○: slight smear but no practical problem; Those were evaluated as x.

(Fog) As for fog on the image, toner fog on a white background portion of the image was visually determined.も の: very good without fog, 、: practically problematic with fog, and x: practically fogged with significant fog.

(Toner replenishing property) With respect to toner replenishing property, the state of powder properties of the toner was measured using a powder tester (manufactured by Hosokawa Micron Corporation), and the loose apparent specific gravity was 0.400 to 0.1. 420, when the angle of repose is 35 ° or less, ◎, when the apparent apparent specific gravity is 0.380 to 0.400, when the angle of repose is 35 to 40 °, ○, when the apparent apparent specific gravity is 0.380 or less, the angle of repose is 40 ° or more was evaluated as x.

[0036]

[Table 1]

[0037]

According to the present invention, a toner excellent in offset resistance and smear resistance can be provided.

[0038]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Fukuda Examiner, Yoshio Sugano, Osaka International Building Minolta Camera Co., Ltd. 2-3-13 Azuchicho, Chuo-ku, Osaka City (56) References JP-A-6-67455 (JP, A) JP-A-6-75422 (JP, A) JP-A-6-89044 (JP, A) JP-A-6-110249 (JP, A) JP-A-61-62052 (JP, A) JP-A-61-62056 (JP, A) JP-A-3-111856 (JP, A) JP-A-60-217366 (JP, A) JP-A-60-217367 (JP, A) JP-A-4-274248 (JP JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. A styrene-acrylic copolymer resin,
Colorant and melt viscosity at 140 ° C of 0.5 CPS
A toner for developing an electrostatic latent image, characterized by containing a polyethylene wax having a penetration of 3.0 dmm or less and less than 10 CPS. 2. The melt viscosity at 140 ° C. is 1
0 to 10 ⁶ CPS ethylene-based polyolefin polymer
2. The electrostatic device according to claim 1, further comprising:
Latent image developing toner.