JP2000172003A - Developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a developer which hardly generates a development ghost, does not cause unevenness in image density even when the toner is allowed to stand at high temperature and high humidity, can form a stable image over a long period of time and prevents the occurrence of voids in letters even in a contact transfer system. SOLUTION: The developer contains toner particles and additives which are fine titanium dioxide particles of 30-100 nm average primary particle diameter surface-treated with a silane compound and/or a silicone oil and fine silica particles of 7-20 nm average primary particle diameter surface-treated with a silicone oil and containing 5.5-9.0 wt.% carbon derived from the silicone oil. The amount of the fine titanium dioxide particles and that of the fine silica particles are 0.3-1.2 pt.wt. and 0.8-1.6 pt.wt., respectively, based on 100 pts.wt. toner particles. The developer is preferably used as a magnetic one-component developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used in electrophotography.

[0002]

2. Description of the Related Art In recent years, dry developing methods in electrostatic copying have begun to be used in the field of personal copying for individuals, such as printers and facsimile machines. In order to respond to
Improvements in image forming methods have been made. In electrophotography, the two-component developing method is the most widely used method, but the developer deteriorates due to toner particles adhering to the carrier surface, and only the toner is consumed. Since the concentration ratio of the toner inside decreases, the mixing ratio with the carrier must be kept constant. As a result, there is a disadvantage that the developing device becomes large. On the other hand, the one-component developing method does not have the above-mentioned drawbacks and has advantages such as downsizing of the apparatus.

The one-component developing system includes a non-magnetic one-component developing system and a magnetic one-component developing system. The former method is
Although suitable for colorization, the force carried by the developer carrier mainly depends only on the amount of charge of the developer, and thus there is a problem of causing fog, contamination inside the machine, and the like. It is not mainstream. On the other hand, the latter method does not have these problems, but has a problem common to the one-component developing method that a developing ghost is more likely to occur as compared with the two-component developing method.

[0004] Various attempts have been made to improve this problem. For example, Japanese Patent Application Laid-Open No. 1-276174 discloses a technique for suppressing the occurrence of ghost by providing a resin layer made of phenol resin and carbon having conductivity and surface lubricity on the surface of a developer carrier. I have. Japanese Patent Application Laid-Open No. 7-28151 proposes to provide a film having Mo, H, and O on a base of a developer carrying member. By using these development carriers, charge-up of the toner can be suppressed, and ghosting can be prevented. However, these developer carriers have a low charging ability of the sleeve itself, so that when the toner is left on these developer carriers, particularly at high temperature and high humidity, the charge amount of the toner is reduced. This causes a problem that low image density and uneven image density occur.

In recent years, a charging / transfer system without using a corotron has been adopted to prevent generation of ozone from the viewpoint of ecology. Is a problem. Although this problem has been improved to some extent by using, for example, an external additive subjected to a specific surface treatment, there remains a problem that the effect is insufficient when transferring to an OHP sheet or the like. .

Furthermore, in a small-sized machine using a one-component developer, it is necessary to keep the price of the apparatus main body low, so that a mechanism for cleaning, for example, untransferred toner and paper dust has a very simple structure. And there is a problem that cleaning becomes insufficient. The talc contained in the paper easily adheres to the surface of the photoconductor surface layer. In particular, in the case of an organic photoreceptor using a polycarbonate or the like for the surface layer, the adhesiveness is highest, and when paper containing 5% or more of talc is used, paper powder adheres remarkably to the photoreceptor surface. In particular, the resistance of the surface of the photoreceptor is reduced by absorbing water at high temperature and high humidity, and thus the latent image cannot be maintained. Therefore, cleaning must be performed sufficiently.

In order to cope with this problem, a method has been proposed in which an abrasive such as strontium titanate is added to the surface of toner particles. In such a case, there is a problem in that the external additive itself adheres to the surface of the photoreceptor and fog is deteriorated.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to solve the problems of the prior art. That is, the first object of the present invention is to form a stable image for a long period without developing ghost, and even when toner is left under high temperature and high humidity, image density unevenness does not occur. It is to provide a developer which is possible. A second object of the present invention is to
It is an object of the present invention to provide a developer which does not cause a void in a character even in a contact transfer system. A third object of the present invention is to
It is an object of the present invention to provide a developer which does not cause image deletion under high temperature and high humidity even when using paper having a large talc content and has no secondary obstacle.

[0009]

Means for Solving the Problems The present inventors treated titanium oxide fine particles having a specific average primary particle diameter, which had been surface-treated with a silane compound and / or silicone oil, as external additives, and treated with silicone oil. The present inventors have found that the above object can be achieved by using silica fine particles having a specific carbon content and a specific average primary particle diameter, and completed the present invention.

That is, the developer of the present invention has an average primary particle diameter of 30 to 100, the surface of which is treated with toner particles and a silane compound and / or silicone oil as an external additive.
The surface is treated with titanium oxide fine particles having a thickness of 5 nm and silicone oil, and the amount of carbon derived from the silicone oil is 5.
An average primary particle diameter of 5 to 9.0% by weight is 7 to 20 nm.
And the added amount of the titanium oxide fine particles and the added amount of the silica fine particles are respectively equal to the toner particles 10.
0.3 to 1.2 parts by weight and 0.8 to 0 parts by weight
1.6 parts by weight.

In the developer of the present invention, the volume average particle diameter of the toner particles is preferably from 5.0 to 8.0 μm, and the binder resin of the toner particles is preferably a polyester resin. Further, the developer of the present invention is preferably a magnetic one-component developer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the developer of the present invention, the reason why the external additive exerts an effect on image density unevenness after being left at high temperature and high humidity is to improve fluidity and chargeability which are considered to be a main cause of the problem. To prevent toner fluidity from deteriorating due to the embedding of silica fine particles, which are the main external additives, into the toner surface, by using titanium oxide fine particles having a relatively large particle size as spacers between the toner particles. It is considered that both the titanium fine particles have been subjected to the hydrophobic treatment and are difficult to absorb moisture, and the titanium oxide fine particles having relatively low electric resistance promote the charge exchange between the toner particles, and the rising of the charge is improved. It is considered that the ghost that usually occurs is also improved.

Further, in the developer of the present invention, the reason why the titanium oxide fine particles used as an external additive exerts an effect on the image flow due to the adhesion of paper powder to the surface of the photoreceptor without causing secondary obstacles. Since the titanium oxide fine particles have an appropriate particle size, they are well dispersed on the surface of the toner particles and are dispersed on the surface of the toner with little aggregation,
It is also presumed that the toner does not adhere to the photoreceptor by exerting a polishing effect because it is hard to be detached, and as a result, charging failure of the toner is not caused.

Further, the reason why the external additive in the developer of the present invention is effective in omission during transfer is presumed as follows. That is, conventionally, it is known that silica treated with silicone oil is effective in removing during transfer. However, the amount of carbon derived from silicone oil in conventional silica treated with silicone oil is about 5%. However, it was not sufficiently effective for OHP sheets. Therefore, in the present invention, by increasing the amount of treated silicone oil, and by using titanium oxide fine particles having a slightly larger particle size than silica fine particles, the adhesion to the photoreceptor is further reduced, and the transferability is significantly improved. It is supposed to be. Here, when the surface treatment amount of the silicone oil is increased, the fixing property is slightly deteriorated, so that a polyester resin having a wide fixing latitude is preferably used as the binder resin used for the toner.

The particle diameter of the titanium oxide fine particles used as an external additive of the developer of the present invention is in the range of 30 to 100 nm, more preferably 40 to 70 nm. When the particle size is smaller than 30 nm, the effect of removing paper powder and the like is small, and the talc content is 5%.
When the above-mentioned paper is used, image deletion occurs, and when it is larger than 100 nm, the effect of suppressing the development ghost is reduced, and the photoconductor is worn to shorten the life of the photoconductor.

The addition amount of the titanium oxide fine particles is 0.3 to
The range is 1.2% by weight, and the preferred range is from 0.5 to 1.1% by weight, depending on the particle size of the toner particles.
If the addition amount is less than 0.3% by weight, the effect of suppressing development ghosts is reduced. If the amount is more than 1.2% by weight, the developability under high temperature and high humidity is reduced.

The particle size of the silica fine particles used as an external additive of the developer of the present invention is in the range of 7 to 20 nm. When the particle size is smaller than 7 nm, it is difficult to uniformly disperse the toner particles on the surface of the toner particles, and image unevenness is likely to occur. When the particle size is larger than 20 nm, the effect on transfer omission tends to decrease, and powder fluidity is imparted to the toner particles. Insufficient ability.

The amount of silica added is 0.8 to 1.6% by weight.
The preferred range is 1.0 to 1.4% by weight, depending on the particle size of the toner. If the addition amount is less than 0.8% by weight, the fluidity of the toner particles deteriorates, which tends to cause a problem in image unevenness and storage stability, and also tends to reduce the effect on omission during transfer. The amount added is 1.
If it is more than 6% by weight, problems such as adhesion to the photoreceptor are likely to occur.

The amount of carbon derived from the silicone oil in the silica fine particles must be in the range of 5.5 to 9.0% by weight. If the carbon content is less than 5.5% by weight,
In particular, omission during transfer to an OHP sheet or the like is likely to occur,
On the other hand, if the content exceeds 9.0% by weight, the aggregation of the silica fine particles increases, making it difficult to uniformly disperse the particles on the surface of the toner particles, easily causing image unevenness, and deteriorating the fixing performance of the toner.

The method for producing titanium oxide fine particles used in the present invention is, for example, a method in which core particles are prepared by a sulfuric acid method while controlling the particle size by a reaction rate during hydrolysis and the like, and then the surface is treated with a silane compound and / or silicone oil. It can be obtained through a treatment, filtration, drying and pulverization steps.

The silica fine particles can also be obtained by a conventionally known production method, and the amount of the silicone oil to be treated is reduced to 5.5 to 9.0% by weight based on the silica fine particles. It needs to be adjusted so that

In the present invention, the silane compound used for the surface treatment of the titanium oxide fine particles means a silane derivative such as chlorosilane and alkoxysilane and a silazane derivative. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane Examples thereof include silane and hexamethyldisilazane, but the silane compound in the present invention is not limited to these compounds.

The silicone oil used for the surface treatment of the titanium oxide fine particles and the silica fine particles includes:
For example, dimethyl silicone oil, alkyl-modified silicone oil, chlorophenyl silicone oil, fluorine-modified silicone oil, amino-modified silicone oil and the like can be mentioned.

The toner particles are composed of a colorant and a binder resin. Colorants include carbon black, aniline blue, chrome yellow, phthalocyanine blue, rose bengal, C.I. I. Pigment Red 48: 1,
C. I. Pigment Red 12: 2, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12,
C. I. Pigment Blue 15: 1 and the like can be exemplified as typical examples.

In the present invention, when the toner particles are used as a magnetic one-component developer, the magnetic powder dispersed in the binder resin may be a known magnetic material, for example, a metal such as iron, cobalt, nickel or the like. These alloys, Fe
Metal oxides such as ₃ O ₄ , γ-Fe ₂ O ₃ , cobalt-added iron oxide, various ferrites such as Mn-Zn ferrite, Ni-Zn ferrite, magnetite, hematite, etc. can be used. Those treated with a surface treatment agent such as a ring agent or a titanate coupling agent, or those coated with a polymer can also be used.

The mixing ratio of the magnetic powder is preferably in the range of 30 to 70% by weight based on the whole toner particles.
More preferably, it is in the range of 35 to 65% by weight. When the amount of the magnetic powder is less than 30% by weight, the binding force of the toner by the magnet of the toner carrier is reduced, and toner scattering and fogging occur. On the other hand, if it exceeds 70% by weight, there is a problem that the image density is reduced.

The average particle size of these magnetic powders is 0.1.
Those having a thickness of about 0.05 to 0.35 μm are preferably used from the viewpoint of dispersibility in a binder resin.

Means for controlling the charge amount of the developer of the present invention include, for example, fluorine surfactants, chromium dyes such as chromium salicylate complex, and copolymers containing maleic acid as a monomer component. Molecular acids, quaternary ammonium salts, azine dyes such as nigrosine, carbon black and the like can be used.

In the present invention, known resins can be used as the binder resin for the toner particles. For example, homopolymers and copolymers consisting of one or more vinyl monomers can be used. Typical vinyl monomers include:
Styrene, p-chlorostyrene, vinyl naphthalene; for example, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; for example, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, benzoic acid Vinyl esters such as vinyl acrylate, vinyl butyrate, vinyl formate, vinyl stearate, and vinyl caproate; for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n acrylate -Ethylenic monocarboxylic acids such as octyl, 2-chloroethyl acrylate, phenyl acrylate, methyl-α-chloroacrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate, and esters thereof; for example, acrylonitrile, methacrylic acid; Substituted ethylenic monocarboxylic acid such as nitrile and acrylamide; for example, ethylenic carboxylic acid such as dimethyl maleate, diethyl maleate, dibutyl maleate and the like; esters thereof; for example, vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl Vinyl ketones such as ketones; vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether and vinyl ethyl ether; vinylidene halides such as vinylidene chloride and vinylidene chlorofluoride; N-vinyl pyrrole;
Examples thereof include N-vinyl compounds such as vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone, and in consideration of the fixing characteristics and storage stability of the toner, a styrene-acrylic acid copolymer, a polyester resin, and the like. Is preferably used. In the present invention, it is most preferable to use a polyester resin as the binder resin.

In the present invention, a releasing agent may be added to the toner particles in order to improve the offset resistance. As the release agent, paraffin having 8 or more carbon atoms,
Polyolefins and the like are preferable, and for example, paraffin wax, paraffin latex, microcrystalline wax and the like, or polypropylene and the like can be used.

The toner particles in the present invention can be produced by any known method, and particularly preferably by a pulverization method. That is, a method is preferred in which a binder resin, a magnetic fine powder, a release agent, a colorant, and the like are melt-kneaded using a hot kneader, cooled, pulverized and classified to obtain a toner.

The toner particles used in the present invention have a volume average particle size D50 of 5.0 to 8.0 μm, preferably 5.5 to 7.0 μm.
A range of 0 μm is preferable from the viewpoint of the balance between image quality and toner consumption per sheet. When D50 is smaller than 5.0 μm, the development density is lowered and fogging is liable to occur. On the other hand, when D50 is larger than 8.0 μm, the granularity of the toner particles is deteriorated.

[0033]

The present invention will be described below in detail with reference to examples. The particle size of the toner particles used in the present invention is a value measured with a particle size analyzer TA-II manufactured by Coulter Counter Co., Ltd. at an aperture diameter of 100 μm. The particle size of the external additive is a value determined from a scanning electron micrograph. Further, the carbon content of silica is a value measured using a carbon measuring device EMIA-110 manufactured by Horiba, Ltd.

Example 1 Binder resin: polyester resin 50 parts by weight (alcohol component: propylene oxide adduct of bisphenol A, acid component: terephthalic acid, MI: 5 g / 10 min, Tg: 60 ° C.) magnetite (particle size: 0) .25 μm) 45 parts by weight Negative charge control agent 1.5 parts by weight (Fe-containing azo dye, trade name: T77, manufactured by Hodogaya Chemical Industry Co., Ltd.) Polypropylene wax 3.5 parts by weight (trade name: 660P, Sanyo) Kaseisha)

The above-mentioned materials were powder-mixed by a Henschel mixer, and kneaded by an extruder at a set temperature of 140 ° C. After cooling, the mixture was roughly pulverized and finely pulverized to obtain a pulverized product having a 50% volume diameter D50 of 5.8 μm. Further, the pulverized material was classified, and the volume D50 = 6.2 μm, 4 μm or less: 2
A toner classification product of 2% by number was obtained. Dimethyl silicone oil-treated silica fine particles having a particle size of 12 nm (carbon content 7.5% by weight) based on 100 parts by weight of the obtained toner classified product.
1.2 parts by weight and 0.6 parts by weight of titanium oxide fine particles having an average primary particle size of 50 nm and surface-treated with 10% by weight of decyltrimethoxysilane were externally added using a Henschel mixer to obtain a toner.

The toner thus prepared was used as a one-component developer, and its evaluation was evaluated by Laser Press 43.
00 (manufactured by Fuji Xerox) under the following conditions. Development bias (AC) = 1.8 kVp-p (frequency 2.0
kHz) developing bias _{(DC) = - 300V V High} = -420V, V Low = -120V image bearing member: organophotoreceptor latent image bearing member, a developer carrying member spacing = 250 [mu] m copy using polycarbonate surface layer binder Paper: Copy paper with talc content of 8.9% by weight (only OHP sheet is used during the evaluation during transfer omission) Test environment: 10 ° C / 15% RH (LL) and 28 ° C /
85% RH (HH)
After printing 0 sheets, the sample was left overnight under the environment, and an image sample was taken thereafter. The evaluation contents are the initial image quality and the image quality after printing 5,000 sheets. The image density was measured using an X-rite densitometer, and the ghost evaluation was obtained by copying three solid images in parallel on the half surface in parallel with the process direction and then copying the entire solid image. In solid images,
On the other hand, judgment was made based on the density difference between the portion corresponding to the non-image portion and the portion corresponding to the image portion of the solid image in which only the previous copy was made. For image flow, make 5,000 copies,
The evaluation was performed using a solid image left overnight.

Example 2 The titanium oxide fine particles surface-treated with 10% by weight of decyltrimethoxysilane used in Example 1 were further treated with 10% by weight of dimethyl silicone oil based on the titanium oxide fine particles. Evaluation was performed in the same manner as in Example 1.

Example 3 D50 of the classified product: 5.3 μm, 4 μm or less: 45% by number, 1.5 parts by weight of treated silica fine particles (7.5% by weight of carbon) and 0.7 parts by weight of titanium oxide fine particles. The evaluation was performed in the same manner as in Example 1 except that the evaluation was performed. Example 4 Evaluation was performed in the same manner as in Example 2 except that the carbon amount of the treated silica fine particles was 8.5% by weight.

Comparative Example 1 Evaluation was carried out in the same manner as in Example 1 except that the amount of the titanium oxide fine particles was changed to 0.2 parts by weight. Comparative Example 2 Evaluation was performed in the same manner as in Example 1 except that the amount of the titanium oxide fine particles was changed to 1.3 parts by weight. Comparative Example 3 Evaluation was performed in the same manner as in Example 2 except that the carbon content of the treated silica fine particles was 4.5% by weight. Comparative Example 4 Evaluation was performed in the same manner as in Example 1 except that the primary particle diameter of the titanium oxide fine particles was changed to 20 nm.

COMPARATIVE EXAMPLE 5 Except that the carbon content of the treated silica fine particles was changed to 10% by weight,
Evaluation was performed in the same manner as in Example 2. Comparative Example 6 Evaluation was performed in the same manner as in Example 1 except that the primary particle diameter of the titanium oxide fine particles was changed to 120 nm. Comparative Example 7 Evaluation was performed in the same manner as in Example 1 except that the primary particle diameter of the treated silica fine particles was changed to 6 nm.

Comparative Example 8 Evaluation was performed in the same manner as in Example 1, except that the primary particle diameter of the treated silica fine particles was changed to 24 nm. Comparative Example 9 Evaluation was performed in the same manner as in Example 1 except that the amount of the treated silica fine particles was changed to 0.7 parts by weight. Comparative Example 10 Evaluation was performed in the same manner as in Example 1 except that the amount of the treated silica fine particles was changed to 1.8 parts by weight.

Table 1 below summarizes the evaluation results.

[Table 1] Note 1) Development ghost ○: Density difference less than 0.05 △: Density difference 0.05 to less than 0.1 ×: Density difference 0.1 or more Note 2) Omission during transfer ○: Not generated △: Slight on OHP sheet ×: Clearly visible on OHP sheet Note 3) Image deletion ○: Not generated △: Generated only at the edge of paper ×: Also generated on image area Note 4) Photoconductor scratches / adhesion (visual at the end of test) ○: not generated ×: generated

[0043]

As described in detail above, since the developer of the present invention has the above-mentioned structure, the use of the developer can cause deterioration in image quality after leaving it under high temperature and high humidity and adhesion of paper powder to the photoreceptor. , The occurrence of development ghosts and omissions during transfer are small, and image density unevenness does not occur, and image quality with stable density can be obtained for a long period of time.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsu Torigoe 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Tomohiro Takeda 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Shinhei Takagi 1600 Takematsu, Minami Ashigara, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Takatoshi Fujii 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Masahiro Uchida 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Address F-term in Fuji Xerox Co., Ltd. (reference) 2H005 AA08 CA12 CA26 CB07 CB13 EA05 EA07 FA06 FC03

Claims (1)

[Claims] Claims: 1. A toner particle, and titanium oxide fine particles having an average primary particle diameter of 30 to 100 nm whose surface is treated with a silane compound and / or silicone oil as an external additive;
The surface is treated with silicone oil and contains silica fine particles having an average primary particle diameter of 7 to 20 nm in which the carbon content derived from the silicone oil is 5.5 to 9.0% by weight. The addition amount of the silica fine particles is 0.3 to 100 parts by weight of the toner particles.
A developer characterized by being 1.2 parts by weight and 0.8 to 1.6 parts by weight.