JPH0812447B2 - Toner and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toner for developing an electrostatic charge image in electrophotography, electrostatic recording, electrostatic printing and the like, and a method for producing the toner.

2. Description of the Related Art In an electrophotographic method using a dry developing method, fixing is usually performed after developing an electrostatic image with toner. This quantification is performed by transferring the toner image obtained by development from the photoconductive photoreceptor onto a transfer sheet such as paper, and then fixing the toner image onto the transfer sheet or copy sheet. As a fixing method at that time, a heat roll fixing method in which pressure heating is performed by a heating roll is generally widely adopted.

The above heat roll fixing method is excellent in that the heat efficiency is high and the fixing can be performed quickly, and it is particularly suitable for a high speed copying machine.

However, in this heat roll fixing method, a so-called offset phenomenon is likely to occur in which a part of the toner adheres to the heating roll from the transfer sheet during fixing and stains the next copy sheet. Conventionally, various attempts have been made to prevent such an offset phenomenon, but in general,
JP-A-50-27546, JP-A-50-93647, JP-A-51-47
There is used a method described in JP-A No. 622, etc., in which a polyolefin wax is added to impart a releasing property to a molten toner.

Further, JP-A-55-156958 discloses that the cleaning property is improved by adding a polyolefin wax having a viscosity in a certain range. The present inventor has found that among such polyolefin waxes, polyethylene wax has particularly excellent cleaning properties for organic photoreceptors.

However, if polyethylene wax is simply added, the compatibility between the binder resin and the polyethylene wax is extremely poor. Therefore, the polyethylene wax is less likely to be taken into the binder resin, and polyethylene wax particles are released outside the toner particles.
The free polyethylene wax particles make the chargeability of the toner unstable and lower the image density. In addition, the presence of free polyethylene wax particles in the toner significantly reduces the fluidity of the toner, and the free polyethylene wax particles contaminate the surface of the toner carrier such as the carrier and the developing cylinder, thereby improving the durability life of the toner. There was a problem that it decreased.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner having stable chargeability and excellent offset property, and a method for producing the same.

Another object of the present invention is to provide a toner having excellent fluidity, little contamination of a toner carrier, and excellent cleaning property, and a method for producing the toner.

Means and Actions for Solving Problems The above object of the present invention is to provide a toner comprising at least a binder resin and a colorant and containing 0.5 to 10% by weight of polyethylene wax, and the external toner particles per 100 toner particles. This is achieved by a toner having 10 or less polyethylene wax particles of 1 μ or more liberated in the inside thereof.

Such a toner having a small amount of free polyethylene wax particles is composed of at least a binder resin and a colorant, and in the method for producing a toner containing 0.5 to 10% by weight of polyethylene wax, the melt viscosity of the binder resin is 10 ³ poise or more. Under the following conditions, the toner, the colorant and the polyethylene wax can be melt-kneaded to provide a toner production method.

That is, when a toner raw material blended so as to contain 0.5 to 10% by weight of polyethylene wax is melt-kneaded under the condition that the viscosity of the binder resin during melt-kneading is less than 10 ³ poise, it is further crushed and classified to obtain a product. The number of polyethylene wax particles released to the outside of the toner particles after being formed exceeds 100 particles per 100 toner particles. When the amount of the free polyethylene wax particles is large as described above, the chargeability of the free polyethylene wax particles is different from that of the toner particles, so that the chargeability of the obtained toner becomes nonuniform and unstable, and the image density is lowered. Cause. Further, polyethylene wax is significantly more liable to be deformed by mechanical shock than the binder resin, so that the force applied to the toner in the developing device causes the free polyethylene wax particles to form on the surface of the toner carrier such as the carrier or the developing cylinder. It adheres, causes pollution, and shortens the durable life of the toner.
In addition, when free polyethylene wax particles are present in the toner, the polyethylene wax has higher adhesiveness at room temperature than the binder resin, so that the fluidity of the toner is reduced, and this is also the cause of shortening the durable life of the toner. Becomes

On the other hand, when the toner raw material containing 0.5 to 10 wt% of polyethylene wax is melt-kneaded under the condition that the viscosity of the binder resin during melt-kneading is 10 ³ poise or more, the polyethylene wax is highly viscous sheared by the binder resin during the melt-kneading. A force is applied to form fine particles that can be dispersed in the binder resin. When a kneaded product in which such polyethylene wax is dispersed in fine particles is pulverized and classified, in the finely divided toner, the state in which the fine polyethylene wax particles are still held in the binder resin is maintained, The production of polyethylene wax particles released to the outside of the particles is remarkably reduced, and the condition of not more than 10 particles per 100 toner particles is achieved. As a result, a toner having stable chargeability, less contamination on the surface of the toner carrier, and excellent fluidity is obtained, and excellent cleaning property is obtained even for an organic photoreceptor.

The melt viscosity of the binder resin is preferably as high as possible from the viewpoint of finely dispersing the polyethylene wax. However, when the binder resin is melt-kneaded under the condition that the viscosity exceeds 10 ⁶ poises, a very large shearing force acts on the binder resin, cutting of the polymer chain of the binder resin occurs, and its molecular weight decreases, The offset phenomenon is likely to occur, which is not preferable.

In the present invention, the number of polyethylene wax particles having a particle size of 1 μm or more released outside the toner particles used as an index of the dispersibility of polyethylene wax can be measured using an optical microscope. First, the toner is uniformly dispersed in a dispersion medium such as silicone oil or liquid paraffin at a rate of about 0.2 g / ml, and about 0.02 ml of the toner is applied on a slide glass in an area of about 20 × 40 mm (this When the toner particles are 1
Disperse well until they are separated into individual pieces),
Take the photograph and determine the number of toner particles. Next, a photograph is taken through the polarizing plate in the same field of view at the same magnification. At this time, free polyethylene wax particles of 1 μm or more are observed as bright white particles in the dark field due to the toner color because of their crystallinity. Therefore, by calculating the number of these white particles, they are released to the outside of the toner. The number of the above-mentioned polyethylene wax particles of 1 μ or more per 100 toner is calculated.

As the binder resin used in the present invention, homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene and their substitution products; styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-
2-ethylhexyl acrylate copolymer, styrene-
Octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, 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-acrylonitrile- Indene copolymer,
Styrene-based copolymers such as styrene-maleic acid copolymer and styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyester, polyurethane, polyamide, epoxy resin, polyvinyl Butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, and the like can be used alone or in combination. Among these fats, styrene resins and polyester resins are particularly preferable.

Furthermore, the binder resin of the present invention preferably has a weight average molecular weight of 100,000 or more and a weight average molecular weight / number average molecular weight ratio of 10 or more. When such a resin is used, free polyethylene wax particles are obtained. A toner with less toner is obtained. The molecular weight of the binder resin is measured by gel permeation chromatography. The measurement conditions are as follows: Tetrahydrofuran is used as a solvent at a flow rate of 1 ml per minute at a temperature of 25 ° C., and 0.5 ml of a tetrahydrofuran sample solution having a sample concentration of 8 mg / ml is injected. As a column, a plurality of commercially available polystyrene gel columns may be combined in order to accurately measure the molecular weight region of 10 ³ to 2 × 10 ⁶ , for example, Shodex manufactured by Showa Denko KK
A combination of A-802, 803, 804, 805 is good. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value and the count number of a calibration curve prepared from several kinds of monodisperse polystyrene standard samples. As a standard polystyrene sample for creating a calibration curve, for example, Pressure
The molecular weight of Chemical Co. or Toray Soda Kogyo Co., Ltd. is 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ ,
It is suitable to use those of 1.1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ and at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

The melt viscosity of the binder resin was measured using a Koka type flow tester manufactured by Shimadzu.

Further, as the polyethylene wax used in the present invention, the density measured by JIS K6760 method is 0.9 or more, 14
The melt viscosity at 0 ° C. is preferably 10 ² to 10 ⁵ centipoise. The amount of polyethylene wax added is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight in the toner. If the amount of polyethylene wax added is less than 0.5% by weight, the effect of preventing offset development and the improvement of the cleaning property are not observed, and if it exceeds 10% by weight, the polyethylene wax particles liberated tend to exceed the number specified by the present invention. , Not preferable.

As the colorant used in the present invention, conventionally known carbon black, copper phthalocyanine, iron black and the like can be used. When the toner is a magnetic toner, it should contain a ferromagnetic element such as iron, cobalt, nickel, etc., or a magnetic substance such as an alloy or compound of iron, cobalt, nickel, manganese, etc. such as magnetite, hematite, ferrite, etc. May be.

Further, in the toner of the present invention, if necessary, a conventionally known charge control agent, lubricant, conductivity imparting agent, etc., such as
Carbon black, nigrosine, metal complex salt, colloidal silica powder, fluorine thread resin powder, metal salt of higher fatty acid, etc. may be added.

Further, as the manufacturing method used in the present invention, a manufacturing method having a pre-mixing step of the toner material, a melt-kneading step, a pulverizing step and a classification step is preferable, and particularly, the melt-kneading step includes a roll mill, a kneader, an extruder and the like. 80-230 ° C, especially 1
It is preferable to carry out at a temperature of 00 to 200 ° C.

The toner is mixed with carrier particles such as iron powder, glass beads, nickel powder, and ferrite powder, if necessary, and used as a developer for an electric latent image. The toner of the present invention can be used for developing a latent image on any photoreceptor. For example, those having an organic polymer layer on the surface, organic photoconductor,
It is applicable to photoconductors such as amorphous selenium, amorphous silicon, and zinc oxide, but those having a layer having an organic polymer on the surface are particularly preferable because the polyethylene wax exhibits an excellent cleaning effect.

EFFECTS OF THE INVENTION As described above, according to the present invention, by containing the polyethylene wax in a good dispersion state, the offset prevention property and the fluidity are excellent, the toner carrier is less contaminated, and the durability or continuous copying property is excellent. Toners and methods of making the same are provided.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1 Styrene-2-ethylhexyl acrylate copolymer (copolymerization ratio = 82.5: 17.5; weight average molecular weight (Mw) = 43000)
0, weight average molecular weight (Mw) / number average molecular weight (Mn) = 47) 1
00 parts by weight, polyethylene wax (density = 9.5 to 0.97, 1
6 parts by weight of melt viscosity at 40 ° C. = about 2.7 × 10 ² centipoise), 60 parts by weight of magnetite and 2 parts by weight of nigrosine were premixed, and then melt-kneaded at 160 ° C. by an extruder. The melt viscosity of the styrene-2-ethylhexyl acrylate copolymer at 160 ° C. was about 10 ⁴ poise.

After cooling the melt-kneaded product, it is crushed to the toner particle size by an air jet type crusher, and then classified by 5 to 15
Particles of μ were collected and used as a toner.

When the number of polyethylene wax particles having a particle size of 1 μm or more released from the toner was measured using an optical microscope, the number of free polyethylene wax particles was about 3 for every 100 toner particles.

For 100 parts by weight of this toner, colloidal silica 0.4
A part by weight was added to obtain a developer. The developer was evaluated using a commercially available copying machine (trade name NP-5540, manufactured by Canon Inc.) that uses an organic photoreceptor. When a durability test was conducted on 100,000 sheets, no offset phenomenon was observed, and it also has excellent cleaning properties for organic photoreceptors, there is no polyethylene wax contamination on the developing cylinder, and image density is high. Maintained a value between 1.35 and 1.43 from the beginning to the end of 100,000 sheets.

Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that the temperature at the time of melt kneading in Example 1 was raised to 200 ° C. Styrene-2
The melt viscosity of the —ethylhexyl acrylate copolymer at 200 ° C. was about 2.5 × 10 ² poise.

The number of free polyethylene wax particles in the obtained toner was 20 per 100 toner, and in the durability test, contamination of polyethylene wax was observed on the surface of the developing cylinder after about 30,000 sheets had passed. This pollution caused a gradual decrease in concentration and a change in concentration. Initially, the image density was 1.22, but it was 1.10 for 30,000 sheets, 1.08 for 50,000 sheets, and 1.05 for 100,000 sheets.

There were no major problems with the offset phenomenon and the cleaning property.

Example 2 Styrene-butyl acrylate copolymer (copolymerization ratio =
75:25, Mw = 270,000, Mw / Mn = 31) 100 parts by weight, polyethylene wax (density = 0.95 to 0.97, melt viscosity at 140 ° C. = about 2.6 × 10 ⁴ centipoise) 8 parts by weight, magnetite 60
Parts by weight and 2 parts by weight of nigrosine were used in the same manner as in Example 1.

The viscosity of the binder resin at a kneading temperature of 160 ° C. was about 5 × 10 ³ .

In the obtained toner, the amount of released polyethylene wax was 7 per 100 toners, and good results were obtained.

Example 3 Styrene-butyl acrylate copolymer (copolymerization ratio =
75:25, Mw = 450000, Mw / Mn = 35) 80 parts by weight, a styrene-butadiene copolymer having an insoluble content (about 5%) in a solvent (for example, xylene) (copolymerization ratio = 85: 15) Preliminary mixing in the same manner as in Example 1 by mixing 20 parts by weight, 2 parts by weight of polyethylene wax (density = 0.92, melt viscosity at 140 ° C. = 3.4 × 10 ³ centipoise), 60 parts by weight of magnetite, and 2 parts by weight of nigrosine, A toner was obtained through melt-kneading, pulverization, and classification.

The temperature at the time of kneading was 140 ° C., the viscosity of the binder resin at this temperature was about 5 × 10 ⁵ poise, and the presence of free polyethylene wax particles in the produced toner was not recognized.

Good results were also obtained in the evaluation using a copying machine.

Example 4 A toner was produced in the same manner as in Example 1 except that 100 parts by weight of a styrene-butyl methacrylate copolymer (copolymerization ratio = 60: 40; Mw = 380,000, Mw / Mn = 17) was used, and the toner was manufactured. I did a test.

The melt viscosity of the binder resin at 160 ° C. was about 3 × 10 ⁴ poise, and the number of free polyethylene wax particles in the obtained toner was 4 per 100 toners, which was a good result.

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Claims (2)

[Claims] 1. A toner comprising at least a binder resin and a colorant and containing polyethylene wax in an amount of 0.5 to 10% by weight, wherein, for every 100 toner particles, 1 μ or more polyethylene wax particles liberated outside the toner particles are present.
Toner characterized by being 10 or less. 2. A method for producing a toner comprising at least a binder resin and a colorant and containing polyethylene wax in an amount of 0.5 to 10% by weight under the condition that the melt viscosity of the binder resin is 10 ³ poise or more. A method for producing a toner, which comprises melt-kneading a resin, a colorant and a polyethylene wax.