JPH08220791A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE: To make a toner almost independent of a temp. change and an environmental change, to stabilize the chargeability, etc., and to form a clear image free from fog by adding flaky fine titanium oxide particles to the toner consisting of a colorant and a bonding resin. CONSTITUTION: Flaky fine titanium oxide particles are added to a toner consisting of a colorant and a bonding resin. The average particle diameter of the particles is 5-40nm, preferably 5-30nm and flaky fine titanium oxide particles whose surfaces have been made hydrophobic in an aq. system or further made hydrophobic in a vapor phase are preferably used. The amt. of the particles added to the toner is 0.3-1.7wt.%, preferably 0.5-1.5wt.% of the amt. of the toner and it is selected in accordance with the kind of the toner. The adhesiveness and dispersibility of the particles to the toner are improved, the stuck particles are hardly released and the spenting of carriers is prevented. The toner surface modifying effect of the particles is enhanced because of satisfactory dispersibility and the fluidity of the toner is improved.

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 charge image in electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art In a method of forming an electrostatic latent image on the surface of a photoconductive material by electrostatic means and developing the electrostatic latent image, the storage property (blocking resistance) of the developer used is
Properties such as transportability, developability, transferability, chargeability, and fixability are important. To date, many improved techniques have been proposed. As one of the methods, it is known to externally add an additive to the toner. JP-A-62-113158 discloses a hydrophobic silica fine powder and JP-A-64-62667.
Japanese Patent Laid-Open No. 3-45978 discloses a titanium oxide fine powder.
Japanese Patent Laid-Open Publication No. 2003-242242 proposes a technique of adding a fluororesin fine powder to a developer. Japanese Unexamined Patent Publication (Kokai) No. 6-208241 proposes a technique of using needle-shaped titanium oxide, which is different from ordinary spherical or irregular shapes.

In the conventional addition system of hydrophobic silica, since the silica fine particles themselves have a strong negative chargeability, the increase in charge of the toner at low temperature and low humidity poses a problem. As the demand for high definition and high image quality in recent years has increased in the market, it is indispensable to cope with the reduction in toner diameter. If the particle size becomes finer, the surface area per unit weight increases and the charge amount also increases, so that there is a concern that the image density will decrease and the durability will deteriorate.

In the case of titanium oxide fine particles, the surface activity is originally smaller than that of silica and the like, and the hydrophobicity is not always sufficient, and the fluidity of the toner greatly changes due to environmental changes, so that stable chargeability, transportability, and developability are obtained. However, there is a problem in that the image quality is deteriorated. It is possible to use a large amount of a hydrophobic treatment agent or to use a highly viscous treatment agent to increase the hydrophobicity ratio by force, but agglomeration of particles may occur, which may result in a fluidity imparting ability. There are problems such as deterioration.

In addition to titanium hydrophobized, addition of additives such as hydrophobized silica and resin fine particles to the toner is carried out by adhering to the toner particle surface by electrostatic force or Van der Waals force of the toner particles and the additive. It is generally used, and stirring, a mixer, etc. are often used.

However, it is not easy to uniformly disperse such conventionally known additives on the toner surface, and the additives not yet attached to the toner surface are aggregated. It is difficult to prevent the agglomerates from liberating, so the triboelectric charge amount of the toner becomes unstable, the image density is not constant, the image becomes fogged, and the image quality after continuous copying becomes poor. Had problems such as. In addition, carrier spent and the like also occur due to the separation of aggregates. Although the use of needle-shaped titanium oxide can improve the adhesion to the toner to some extent, the area of the contact surface with the toner is small, and it also has the above-mentioned problems.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is less susceptible to changes in temperature or environment, and electrostatic charge image development having stable characteristics such as chargeability and developability. To provide toner for use.

Another object of the present invention is to provide a toner for developing an electrostatic charge image which prevents carrier spent and the like, has clear image characteristics without fog, and has excellent durability stability.

[0009]

That is, the present invention relates to a toner for developing an electrostatic charge image, characterized in that flaky titanium oxide fine particles are externally added to a toner composed of at least a colorant and a binder resin.

The titanium oxide (titania) added to the toner of the present invention is in the form of flakes, or in other words flat, and due to its unique shape, its adhesion to the toner and dispersibility are different from those of conventional fine particles. In comparison, it is extremely good, and the fine particles attached to the toner are very unlikely to separate. Therefore, spent of the carrier is prevented, stable charging is obtained, and durability performance is improved.

Further, due to the good dispersibility, the effect of surface modification of the toner is great, and good results are also obtained on the improvement of fluidity and the environmental stability of charging.

The titanium oxide used in the present invention can be produced by a wet method and has an average particle size of 5 to 40 nm, preferably 5 to 40 nm.
It is desirable to use those having a particle size of 30 nm, and preferably those having the surface of the fine particles subjected to a hydrophobic treatment in an aqueous system or further subjected to a hydrophobic treatment in a gas phase. The average particle diameter of titanium oxide is the average value of the long diameters of the titanium oxide particles taken by an electron micrograph.

In the hydrophobizing treatment in a water system, mechanical force is applied to disperse the titanium fine particles into the primary particles, so that a gas such as chlorosilanes and disilazanes is produced as a by-product. It is not necessary to use a coupling agent having excellent reactivity, and a highly viscous treatment agent that cannot be used by combining titanium oxide particles in the gas phase can be used.

Therefore, as the treating agent, any one of coupling agents, oils, varnishes, organic compounds and the like can be used.

Examples of the coupling agent preferably used include silane coupling agents and titanium coupling agents, and particularly preferably used are silane coupling agents having the general formula: R ₁ m ₁ SiY ₁ n ₁ [wherein R ₁
Is an alkoxy group, m ₁ is an integer of ₁ to 3, Y ₁ is a hydrocarbon group containing an alkyl group, a vinyl group, a glycidoxy group or a methacryl group, and n ₁ is an integer of ₁ to 3], For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, Trimethylmethoxysilane,
Examples thereof include hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane and n-octadecyltrimethoxysilane.

The amount used is 1-40 parts by weight, preferably 3-30 parts by weight, per 100 parts by weight of titanium fine particles.

The silicone oil used in the present invention is not particularly limited, but the general formula

Embedded image Dimethylpolysiloxane type represented by, general formula

Embedded image Methylhydrogen polysiloxane type represented by

Embedded image A methylphenylpolysiloxane type represented by can be used. Further, if necessary, alkyl modification, amino modification, epoxy modification, epoxy / polyether modification, carboxyl modification, mercapto modification, alcohol modification, fluorine modification and the like may be performed.

In the present invention, the silane coupling agent used for treating titanium treated in an aqueous system in a gas phase is represented by the general formula R ₄ m ₃ SiY ₂ n ₅ [wherein R ₄ is an alkoxy group or chlorine. Atom, m ₃ is an integer of 1 to 3, Y ₂ is a hydrocarbon group containing an alkyl group, a vinyl group, a glycidoxy group or a methacryl group, and n ₅ is an integer of 3 to 1]. Is dimethyldichlorosilane, trimethylchlorosilane, allidimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ
-Methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, dimethylvinylchlorosilane and the like can be mentioned.

The treatment of the fine powder with the silane coupling agent may be a dry treatment in which the fine powder is made into a cloud by stirring and the vaporized silane coupling agent is reacted.

The present invention is applicable to any toner particles as long as the fluidizing agent is externally added and used, for example, toner particles for high speed systems, toners for oilless fixing, magnetic toners or full color toners. It is possible. Further, it may be a toner used as a one-component developer or a two-component developer together with a carrier. Particularly when reproducing a high-definition image, the average particle size is 5 to
Toner particles of 9 μm and even 5-8 μm are used.

Usually, the toner is prepared as particles in which a colorant such as carbon black and other desired additives are dispersed in a binder resin. Resins normally used as binders for toners are, for example, polystyrene resins,
Among poly (meth) acrylic resins and polyolefin resins,
Thermoplastic resin such as polyamide resin, polycarbonate resin, polyether resin, polysulfone resin, polyester resin, epoxy resin, butadiene resin, or heat of urea resin, urethane resin, urea resin, epoxy resin, etc. Curable resins, and further, copolymers, block polymers, graft polymers and polymer blends thereof can be used. The above-mentioned resin is not limited to a resin in a complete polymer state such as a thermoplastic resin, but a resin containing an oligomer or a prepolymer such as a thermosetting resin and a crosslinking agent may be used. Is.

In the case of toner used in high-speed systems, the toner may be fixed on the transfer paper in a short time,
Since it is necessary to improve the separability from the fixing roll,
As the binder resin, a homopolymer or copolymer polymer synthesized from a styrene-based monomer, a (meth) acrylic-based monomer, a (meth) acrylate-based monomer, or a polyester-based resin is used.

In the above binder resin,
The number average molecular weight Mn and the weight average molecular weight Mw are 1000 ≦
Mn ≦ 10000, 20 ≦ Mw / Mn ≦ 70, and 2000 ≦ Mn ≦ 7000 are used.

When used for oilless fixing, the binder resin has a glass transition point of 55 to 80.
C., a softening point of 80 to 150.degree. C., and a gelling component of 5 to 20% by weight is used.

Further, when used as a full-color toner, the binder resin has a glass transition point of 55 to 55.
70 ° C, softening point 80-150 ° C, Mn 2000-1
A linear polyester resin having a molecular weight distribution Mw / Mn of 5000 or less is used.

Further, linear urethane-modified polyester obtained by reacting the above linear polyester resin with diisocyanate, or the above linear polyester resin is modified by graft polymerization, block polymerization, or the like with a styrene-based, acrylic-based, or aminoacrylic-based monomer. The resin described above can also be preferably used.

Various colorants can be used as the colorant. Blue dyes and pigments include CI74100 (metal-free phthalocyanine blue), CI74160 (phthalocyanine blue), CI74180 (fast sky blue).
Etc. can be illustrated as typical ones.

Examples of red dyes and pigments include CI 12055.
(Stalin I), CI 12075 (Permanent Orange), CI 12175 (Resor Fast Orange 3)
GL), CI 12305 (Permanent Orange GT
R), C.I. 11725 (Hansa Yellow 3R), C.I.
21165 (Vulcan Fast Orange GG), C.I.2
1110 (Benzidine Orange G), C.I. 12120
(Permanent Red 4R), C.I.1270 (Para Red), C.I. 12085 (Fire Red), C.I.1
2315 (Brilliant First Scarlet), C.
I.12310 (Permanent Red F2R), C.I.1
2335 (Permanent Red F4R), C.I. 1244
0 (Permanent Ent Red FRL), CI 1246
0 (Permanent Red FRLL), C.I. 12420
(Permanent Red F4RH), C.I. 12450 (Light Fast Red Toner B), C.I. 12490 (Permanent Carmine FB), C.I. 15850 (Brilliant Carmine 6B), etc.

Examples of yellow dyes and pigments include CI 10316
(Naphthol Yellow S), C.I. 11710 (Hansa Yellow 10G), C.I. 11660 (Hansa Yellow 5)
G), C.I. 11670 (Hansa Yellow 3G), C.I.
11680 (Hansa Yellow G), C.I. 11730 (Hansa Yellow GR), C.I. 11735 (Hansa Yellow A), C.I. 11740 (Hansa Yellow RN), C.I.
12710 (Hansa Yellow R), C.I. 12720 (Pigment Yellow L), C.I. 21090 (Benzidine Yellow), C.I. 21095 (Benzidine Yellow G),
C.I.21100 (Benzidine Yellow GR), C.I.2
0040 (Permanent Yellow NCG), C.I.212
20 (Vulcan Fast Yellow 5), C.I. 21135
(Vulcan Fast Yellow R) and the like can be given as a representative example.

As the black pigment, carbon black,
Copper oxide, manganese dioxide, aniline black, activated carbon,
Ferrite, magnetite, etc. can be used.

These colorants may be used alone or in combination of two or more, and are used in an amount of 1 to 10 parts by weight, more preferably 2 to 5 parts by weight, based on 100 parts by weight of the binder resin contained in the toner particles. Is desirable. That is, if it is more than 10 parts by weight, the fixability and translucency of the toner will be deteriorated, while if it is less than 1 part by weight, a desired image density may not be obtained.

The toner may contain a charge control agent, an offset preventing agent and the like. As the charge control agent, both a positive charge control agent and a negative charge control agent can be used.

As the positive charge control agent, nigrosine base EX, Bontron N-01, 02, 04, 05, 07,
09, 10 and 13 (all manufactured by Orient Chemical Industry Co., Ltd.), oil black (manufactured by Central Synthetic Chemical Industry Co., Ltd.), quaternary ammonium salt P-51 (manufactured by Orient Chemical Industry Co., Ltd.), polyamine compound P-52 (Orient Chemical Industry Co., Ltd.) Company),
Sudan Chief Schwarz BB (Solvent Black 3; CI No. 26150), Fett Schwarz HBN (CI No. 26150), Brilliant Spirits Schwarz TN (Farben Fabryken Bayer), alkoxylated amines, alkyls. 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, 38 and 40 (above, manufactured by Orient Chemical Industry Co., Ltd.), Eisenspirone Black TRH, BHH (above. , Hodogaya Chemical Co., Ltd.), Kayaset Black T-22,004 (above, Nippon Kayaku Co., Ltd.), copper phthalocyanine dye S-39 (Orient Chemical Co., Ltd.), chromium complex salt E-81, 82 (above, Orient Chemical Industry Co., Ltd.), zinc complex salt E-84 (Orient Chemical Industry Co., Ltd.), aluminum complex salt E-86
(Orient Chemical Co., Ltd.) and calixarene compounds can be used.

The amount of the charge control agent to be added should be appropriately adjusted depending on the type of toner. Generally, 0.01 to 10 parts by weight of the charge control agent is used with respect to 100 parts by weight of the binder resin of the toner. When it is attached and fixed on the toner surface, it needs less amount than dispersed in the particles,
0.05 to 2 parts by weight is sufficient.

As the offset preventing agent, polyolefin wax such as low molecular weight polyethylene wax and low molecular weight oxidation type polypropylene wax, higher fatty acid wax, higher fatty acid ester wax, sazol wax,
Candelilla wax, carnauba wax and mixtures thereof can be used.

The offset preventive agent is usually 0.1 to 100 parts by weight of the binder resin, depending on the kind of toner.
It is added in an amount of 10 parts by weight, preferably 1 to 5 parts by weight.

In the present invention, flaky titania is mixed with the above toner particles (external addition) to obtain a toner. As a method capable of performing such mixing, conventional methods such as a mechanical pulverization mixing method and conditions may be used, and for example, a mixer such as a Henschel mixer, a super mixer, a powder mixer, a homogenizer can be used.

The amount of the flaky titania added should be appropriately selected according to the type of toner, but is 0.3 to 1.7% by weight, preferably 0.5 to 1.5, relative to the toner.
It is selected in the range of weight% and added and mixed. If the amount added is too small, the desired fluidity and environmental properties cannot be obtained, leading to image deterioration. If it is too large, the amount of charge is reduced, which causes fog and the like.

The present invention will be described in more detail below with reference to Examples. In the Examples, "parts" means "parts by weight" unless otherwise specified.

[0041]

[Examples] Toner production example : Styrene-acrylic resin 100 parts (acid value: 25, glass transition point (Tg): 60 ° C, softening point (Tm): 120 ° C) Charge control agent (Spiron Black TRH ; Hodogaya Chemical Co., Ltd.) 3 parts ・ Carbon black (Mogal L; Cabot Co., Ltd.) 6 parts ・ Wax (Viscor 605P; Sanyo Kasei Co., Ltd.) 5 parts

The above mixture was thoroughly mixed with a Henschel mixer and melt-kneaded with a twin-screw extruder. The kneaded product was cooled and then roughly crushed. The coarsely pulverized material was finely pulverized by an air jet type pulverizer. Further, the obtained finely pulverized product was classified by an air flow type pulverizer to obtain a volume average particle diameter (D ₅₀ ) of 1
0.2 μm particles were obtained.

Example of production of carrier (binder type microcarrier ) 100 parts of polyester resin (acid value: 15.0, Tg: 65 ° C., Tm: 120 ° C.) 400 parts of magnetic powder (MFP-2: manufactured by TDK) Using the above materials, a carrier having a volume average particle diameter (D ₅₀ : 70 μm) was obtained in the same manner as in the toner production method. The obtained carrier had a saturation magnetization of 56 emu / g and an electric resistance of 7 × 10.
It was ¹² Ω · cm.

Example 1 Hydrophobic flaky titania fine particles (particle size: 0.015 to 0.05) relative to 100 parts of the particles obtained in the above toner production example
2 μm, STT-30A (manufactured by Titanium Industry Co., Ltd.) (1.0 part) was added and mixed with a Henschel mixer to obtain a toner.

A binder type microcarrier was mixed with 5 parts of the obtained toner so that the total amount was 100 parts to obtain a developer.

Using the obtained developer, images were printed on a commercially available plain paper high-speed copying machine (EP-8600; manufactured by Minolta Co., Ltd.), and a durability test of the following 30000 (30K) sheets was conducted. Durability test: N / N environment (25 ° C, 45%) 10K sheets L / L environment (10 ° C, 15%) 10K sheets H / H environment (30 ° C, 85%) 10K sheets

Under each environment, the image after durability was good in terms of fog, sharpness and image density, which were similar to those in the initial stage. The results of the image formation and the durability test are summarized in Table 1.

Each evaluation in Table 1 was carried out as follows. -Image density The image density (ID) value was rounded off to one decimal place.

Fog The obtained images were visually evaluated and ranked as follows. ⊚: Rank 5 (no fog at all). ◯: Rank 4 (almost no fog). B: Rank 3 (some fog is observed, but there is no problem in practical use). X: Ranks 1 to 2 (there is a lot of fog and there are practical problems)

Durability Characteristics After measurement under each environment (after 30K), comprehensive evaluation was performed and ranking was performed as follows. A: No problem at all. ◯: There is no problem in practical use although some characteristics are changed. Δ: There is a change in characteristics, and there is a practical problem in image quality after 30K. X: What did not have 30K.

Example 2 A developer was prepared and tested in the same manner as in Example 1 except that the amount of hydrophobic flaky titania fine particles (STT-30A; manufactured by Titanium Industry Co., Ltd.) was 0.5 part. The results are summarized in Table 1.

Example 3 A developer was prepared and tested in the same manner as in Example 1 except that the amount of hydrophobic flaky titania fine particles (STT-30A; manufactured by Titanium Industry Co., Ltd.) was changed to 1.5 parts. The results are summarized in Table 1.

Comparative Example 1 Development was carried out in the same manner as in Example 1 except that 0.8 parts of hydrophobic amorphous granular titania fine particles (T-805; manufactured by Degussa) were added in place of the flaky titania fine particles in Comparative Example 1 . Agents were prepared and tested. The results are summarized in Table 1.

Comparative Example 2 The same as in Example 1 except that 1.0 part of hydrophobic amorphous granular titania fine particles (TTO-51C; manufactured by Ishihara Sangyo Co., Ltd.) was added in place of the flaky titania fine particles in Comparative Example 2 . Developers were prepared and tested. The results are summarized in Table 1.

Comparative Example 3 A developer was prepared and tested in the same manner as in Example 1 except that 1.0 part of hydrophobic spherical titania fine particles obtained by the following was added in place of the flaky titania fine particles in Example 1. . The results are summarized in Table 1.

Preparation of spherical titania fine particles: Ilmenite ore was dissolved in sulfuric acid, cooled, and then centrifuged. The centrifugally separated stock solution was heated and hydrolyzed, and the obtained titanium hydroxide was baked (350 to 400 ° C.) in a rotary furnace to obtain spherical hydrophilic titanium oxide (particle size: 0.04 to 0.05 μm). . The obtained titanium oxide were added and mixed so that the 20% coupling agent while stirring and mixing in an aqueous a _{(n-C 5 H 11 Si} (OCH 3) 3) with respect to titanium oxide particles. The mixture was dried and crushed to obtain titanium oxide having a hydrophobicity of 50%.

[0057]

[Table 1]

[0058]

The toner to which the flaky fine particles are added according to the present invention is extremely stable against environmental changes, has excellent durability, and can provide a stable high-quality image for a long period of time.

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[Procedure amendment]

[Submission date] December 12, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art In a method of forming an electrostatic latent image on the surface of a photoconductive material by electrostatic means and developing the electrostatic latent image, the storage property (blocking resistance) of the developer used is
Properties such as transportability, developability, transferability, chargeability, and fixability are important. To date, many improved techniques have been proposed. As one of the methods, it is known to externally add an additive to the toner. JP-A-62-113158 discloses a hydrophobic silica fine powder and JP-A-64-62667.
Japanese Patent Laid-Open No. 3-45978 discloses a titanium oxide fine powder.
Japanese Patent Laid-Open Publication No. 2003-242242 proposes a technique of adding a fluororesin fine powder to a developer. Japanese Unexamined Patent Publication (Kokai) No. 6-208241 proposes a technique of using needle-shaped titanium oxide, which is different from ordinary spherical or irregular shapes.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

As the silane coupling agent treatment of the fine powder, a dry treatment of reacting the vaporized silane coupling agent with a fine powder made into a cloud by stirring or the like can be adopted.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0057

[Correction method] Change

[Correction content]

[0057]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Ken Arai, Ken Arai, 2-13-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka, Osaka International Building Minolta Co., Ltd. (72) Inventor Masayuki Hagi, Azuchi-cho, Chuo-ku, Osaka-shi, Osaka 2-chome 3-13 Osaka International Building Minolta Co., Ltd.

Claims (1)

[Claims] 1. A toner for developing an electrostatic charge image, wherein flaky titanium oxide fine particles are externally added to a toner composed of at least a colorant and a binder resin.