JP2864244B2 - Pigments for color toners with functional thin film coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the functionality (dispersion, charging) of a pigment itself by dry-coating a thin film of a metal or a metal oxide on the surface of a pigment powder by a sputtering method. The present invention relates to a pigment for a color toner which has improved characteristics and can be suitably used for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like.

[Prior art and problems] Pigments are mainly used as colorants and materials for improving physical properties of materials.
It is widely used in paints, inks, rubber, plastics, cosmetics, color toners for color electrophotography, and the like.
In each case, the pigment itself is dispersed in another medium to exhibit its function. Color, hiding power, fluidity, storage stability, gloss, weather resistance, chemical resistance, adhesion to base material, waterproofing, etc. There is. Electrophotography further requires electrostatic characteristics.

Conventionally, for the purpose of improving the functions of such pigments,
Surface modification such as hydrated alkali treatment, hydrated alumina-silica treatment, hydrated alumina-titania treatment and silane coupling treatment has been performed.

Recently, a composite powder obtained by driving fine titanium oxide particles into the surface of a nylon powder having a size of several tens of μm has been added to a cosmetic cream for sunscreen and put into practical use. Further, a plurality of powders in which titanium oxide particles are adhered to a mica having a thickness of 0.1 μm without gaps are also used for the same purpose.

When the pigment surface is modified by hydrated alumina treatment or hydrated alumina-silica treatment, etc.
Heating and drying are usually performed in various temperature ranges of 00 ° C,
At this time, it is inevitable that various properties of the pigment are slightly changed as the heating temperature increases. Also,
Impurities such as SO ₄ ²⁻ and Cl ^{2 −} in the raw material to be processed remain in the pigment, which may affect the properties and crystal structure of the pigment.

Further, when a pigment is used by being dispersed in a paint or plastic, the surface of the pigment is not necessarily firmly bonded to the paint or plastic. If a pigment is obtained that has a chemical bond between the pigment and its medium, the properties of the pigment will not be degraded for a long time.

Furthermore, primary color pigments such as yellow, magenta and cyan are used as pigments for color copying toners, and polystyrene resins, styrene-propylene copolymer resins, polyvinyl chloride resins, etc. are used as binder resins for such pigments. Compounding, complex forms such as mixing iron, cobalt, nickel, etc. or alloys or mixtures thereof as a magnetic material or using it as a carrier and mixing a charge control agent such as a metal chelate of alkylsalicylic acid Used as particles. In this case, the charge amount distribution is uniform and stable, the initial characteristics are maintained even when used for a long time, and the charge characteristics do not change, as well as excellent dispersibility and are not affected by changes in temperature or humidity. It is required that there be.

[Object of the invention]

The present invention prevents a change in the properties of the pigment itself, which cannot be avoided by the conventional method for modifying the surface of the pigment, and has the various functions required for the pigment itself to be used as a color toner. This is done for the purpose of causing

[Summary of the Invention]

The present invention provides an ultra-thin dry coating of a metal consisting of titanium, aluminum, silicon or one or a combination of two or more of these oxides having a thickness of 10 to 100 mm on the surface of a pigment powder, or an oxide of the metal. Provided by a sputtering method. That is, the present invention employs a dry coating technique by a sputtering method in place of the conventional pigment surface modification means such as hydrated alumina treatment or hydrated alumina-silica treatment to modify the pigment surface at a low temperature of 100 ° C. or less. The above objectives have been achieved by performing quality.

[Detailed Description of the Invention] The present inventors have applied to a patent application No.
Various attempts were made to coat various metals or metal oxides by the sputtering method using the method and apparatus shown in 61-93223 (filed on April 24, 1986, method and apparatus for coating ultrafine powder). . This experiment has revealed various facts as described below.

In dry coating, if the surface of the pigment is activated by performing reverse sputtering for 10 minutes under a reduced pressure (about 10 ^-2 Tor.) In an argon atmosphere, the adhesion of the dry coating is improved. After applying the dry coating, preferably put into an ethanol solution of vinyltrimethoxysilane, for several minutes with an ultrasonic homogenizer, and subjected to dispersion treatment at room temperature, using a rotary evaporator to remove ethanol at about 50 ℃, By a series of processes of drying, a pigment having various functional thin film coatings including the pigment for a color toner according to the present invention is obtained.

Inorganic pigments that can be the subject of this thin film coating technology include natural products such as clay and mica, graphite, barium yellow, navy blue, cadmium yellow, lead sulfate, strontium chromate, calcium silicate, calcium carbonate, carbon Chromates such as black and aluminum powder, ferrocyanides, sulfides, sulfates, oxides, silicates, short acid salts, and synthetic products such as carbon and metal powders. Methods for producing these pigments include methods such as mechanical pulverization, thermal decomposition, precipitation, precipitation-calcination, solid solution, reduction, electrolysis, coagulation and spraying.

Organic pigments that can be the subject of the thin film coating technology include Hansa Yellow 3G, Lake Red C, Permanent Red 4R, Permanent Carmine FB, Benzidine Yellow G, Naphthol AS-D, Fast Red IT
Azo pigments such as R; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; quinacridone pigments such as 2,9-dichloroquinacridone, 6,13-dihydroquinacridone, quinacridone quinone, and cis quinacridone; Ron-based pigments, perylene-based pigments, anthrapyrazole-based pigments and perinone-based raw materials are exemplified. In the case of a color toner for electrophotography, any known pigment suitable for a color toner can be used.

When such a pigment is charged into a sputtering apparatus and subjected to dry coating of metal or metal oxide, it is desirable to adjust the coating film thickness to about 10 to 100 °. When the thickness is less than 10 mm, it is difficult to obtain the effect of imparting functionality by dry coating, and it is also difficult to achieve uniform coating. On the other hand, if the film thickness exceeds 100 mm, the primary particle size of the pigment may be as small as about 100 mm, and in the case of thick film coating, it takes time and costs, and the characteristics of the pigment itself are dry. 100Å because it may be concealed by the coating film
It is preferable to apply the following ultra-thin dry coating.

The metal or metal oxide to be dry-coated is particularly preferably titanium, aluminum or silicon, or an oxide thereof. In fact, titanium,
When aluminum or silicon is dry-coated on the surface of various pigments to form a strong metal thin film, any metal surface must be covered with an ultra-thin oxide film of about 10 mm before handling in air after this metal coating treatment. become. Functionality is further provided by this oxide film.

For example, in the case of titanium oxide, since the refractive index of ultraviolet light is large, the ultraviolet light resistance of the pigment itself can be improved, and the pigment itself can be provided with electrostatic characteristics required for electrophotography. In the case of aluminum oxide, it is possible to impart compatibility between infrared ray reflection characteristics and a resin, and in the case of silicon oxide, it is possible to improve weather resistance and chemical resistance. Such functions include a method of forming an oxide film after dry coating, titanium oxide,
This can also be achieved by dry-coating aluminum oxide or silicon oxide itself. Dry coating of such an oxide is conveniently performed by using a metal as a target and allowing an appropriate amount of oxygen to exist in a sputtering atmosphere.

In addition to the above-mentioned coating materials, it is possible to improve the ultraviolet resistance by coating with zinc and zinc oxide, and to form a heat ray absorbing film by coating with copper and copper oxide, manganese and manganese dioxide, cobalt and cobalt oxide. Further, it is also possible to form an infrared absorbing film by coating a sulfide such as zinc sulfide, copper sulfide, and cobalt sulfide. In addition, it is also possible to apply a composite dry coating of different materials so as to exhibit various characteristics.

It should be noted that a known silane coupling treatment can be effectively applied to pigments having such a thin film dry coating in many applications. As the silane coupling treatment, any of an aqueous solution method, an organic solvent method, and a spray method can be used, but the organic solvent method is most preferable in terms of quick drying. Examples of the silane coupling agent used include aminosilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, and γ.
-Chloropropylmethyldimethoxysilane, N-β- (N
-Vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride and the like, but its suitability may be determined depending on the type of paint or plastic resin to which the pigment is applied. However, when the pigment is applied for electrophotography as in the present invention, the silane coupling treatment need not be particularly performed.

Some examples of reference experiments in which pigments are modified by applying the thin film coating technique as described above are shown below.

REFERENCE EXPERIMENTAL EXAMPLE 1 2 g of commercially available Shinkasha Red B (red pigment) manufactured by DuPont of the United States was applied to Japanese Patent Application No. 61-93223 (April 1986).
Method and Apparatus for Coating Ultrafine Powder, filed on March 24), and the titanium was coated. Before coating, the surface of the pigment was activated by performing reverse sputtering at a power of 100 W for 10 minutes under a reduced pressure of 2 × 10 ^-2 Tor. In an argon atmosphere, and then using a titanium target. Sputtering was performed under the conditions of 300 W and a pigment temperature of 100 ° C. for 3 hours. As a result, a dry coating of about 50 ° of titanium was applied to the surface of Shinkasha Red B.

After the completion of the sputtering, the treated powder is cooled, taken out of the apparatus, put into a 1 wt.% Methyltrimethoxysilane-ethanol solution (100 ml), and subjected to dispersion treatment at room temperature for 10 minutes using an ultrasonic homogenizer (output: 300 W). The ethanol was distilled off under heating at 50 ° C. using a rotary evaporator to obtain a pigment having a thin film coating.

The obtained pigment was mixed with 100 g of a thermosetting polyester paint composed of a condensate of phthalic acid and a polyol and a melamine resin as a crosslinking agent, using an attritor manufactured by Mitsui Miike Kako Co., Ltd.

This paint is coated on a phosphate-treated minimized spangled molten zinc-iron plate (thickness: 0.35 mm, zinc adhesion amount: 350 g / m ^{2 on} both sides) with an epoxy resin-based primer. Coating and baking were performed at 230 ° C. for 60 seconds on the primer coated surface baked for 2 seconds at a dry film thickness of 15 μm. As a result, a red polyester-coated zinc iron plate was obtained.

The UV resistance of this coated steel sheet was compared with that of a coated steel sheet obtained by coating in the same manner as above except that Shinkasha Red B, which was commercially available, was used as a control.
The evaluation was made according to the outdoor exposure test method specified in (1), attached to the south surface at 35 degrees, at 7-1, Takayashinmachi, Ichikawa City, Chiba Prefecture. That is,
Gloss and color difference after 2 years of exposure test were measured according to JIS Z 8741 and JI
Investigated based on SZ 8730.

As a result, the gloss of the coated steel plate using the pigment coated with the thin film has maintained 80% of the initial gloss,
The color difference was ΔE = 2. On the other hand, the gloss of the coated steel sheet of the control using the commercially available Shinkasha Red B was reduced to 50% of the initial gloss, and the color difference was also changed to 4 in ΔE.

REFERENCE EXPERIMENTAL EXAMPLE 2 A surface of 4 g of graphite (trade name: Sanchrome Yellow GK470) manufactured by Kikuchi Seiyaku Co., Ltd. was subjected to silicon sputtering coating using the same apparatus as in Reference Experimental Example 1. Sputtering conditions used a silicon target, output 500
W, treated at a pigment temperature of 100 ° C. for 1 hour to form a silicon coating having a thickness of about 100 °.

After the end of sputtering, cool and remove from the equipment,
1wt.% Vinyltomethoxysilane-ethanol solution 100ml
The mixture was stirred well at room temperature for 10 minutes using a screw stirrer to perform dispersion treatment. Thereafter, the mixture was heated to 50 ° C. with a rotary evaporator to remove ethanol by distillation, and further heated in air at 100 ° C. for 10 minutes to obtain a pigment having a thin film coating.

The obtained pigment was treated with 40 g of dioctyl phthalate (DOP),
It was added to a vinyl chloride plastisol paint consisting of 100 g of vinyl chloride resin and 40 g of a diluting solvent, mixed well and dispersed.

This paint is coated on a chromic acid-treated minimized spangled molten zinc-iron plate (thickness: 0.35 mm, zinc adhesion amount: 305 g / m ^{2 on} both sides) with an acrylic-modified epoxy resin-based primer, and heated at 230 ° C for 60 minutes. On the primer coated surface baked for 2 seconds, at 210 ℃ so that the dry coating pressure is 200μm
The paint was baked for 80 seconds to obtain a yellow zinc-coated zinc chloride sheet.

An outdoor exposure test similar to that of Reference Experimental Example 1 was performed by comparing the UV resistance of the coated steel sheet with that of a coated steel sheet obtained by coating in the same manner as described above except that commercially available graphite was used as a control. The gloss and color difference two years after the exposure test were evaluated in the same manner as in Reference Experimental Example 1.

As a result, the gloss of the coated steel plate using the pigment with the thin film coating is maintained at 70% of the initial gloss,
The color difference was 4 in ΔE. On the other hand, the gloss of the coated steel sheet of the control example using as-commercial graphite was reduced to 40% of the initial gloss, and the color difference was also changed to 7 in ΔE.

In the test, discoloration was remarkable in the control example using commercially available graphite. This was because hydrogen chloride was produced as a by-product in the process of degradation and decomposition of the vinyl chloride resin by ultraviolet rays. It is thought that this was caused by the reaction with yellow lead to change to white lead chloride. There is little discoloration in the coated steel sheet using the pigment coated with the thin film, and the graphite dry-coated with silicon according to the above method has the function of preventing the dry-coated thin layer from reacting with hydrogen chloride. It is considered that

Reference Experimental Example 3 A surface of 2 g of commercially available phthalocyanine blue No. 700 manufactured by Toyo Ink Co., Ltd. was subjected to aluminum sputtering coating treatment using the same apparatus as in Reference Experimental Example 1. The sputtering conditions were as follows, using an aluminum target, output 500W, pigment temperature 50 ° C, atmosphere 3
The treatment was performed for 10 minutes in an argon gas containing 0% oxygen. As a result, an aluminum oxide coating having a film thickness of about 10 ° was applied to the pigment surface.

After sputtering, cool and remove from the equipment 1w
The solution was put into 100 ml of a t.% aminosilane-methanol solution, and subjected to dispersion treatment at 300 W for 10 minutes using an ultrasonic homogenizer. After processing, use a rotary evaporator at 50 ° C
To remove ethanol by distillation, and then further in air
Heating at 0 ° C. for 10 minutes gave a pigment with a thin film coating.

The obtained pigment was kneaded into 100 g of maleic anhydride-modified polypropylene (trade name: Polytac) manufactured by Idemitsu Petrochemical Co., Ltd. The kneading was performed using a screw-type extruder. And 100μm thickness, 300mm by molding machine
A sheet having a width was prepared, and this sheet was adhered to a chromic acid-treated zinc-iron plate (sheet thickness 0.5 mm, zinc adhesion amount 100 g / mm) by hot pressing at 250 ° C. for 10 minutes.

Reference Example 1 was compared with a film-laminated steel sheet prepared in the same manner as described above except that phthalocyanine blue, which was commercially available, was used as a control example.
And the gloss and color difference two years after the exposure test were evaluated in the same manner as in Reference Example 1. In the middle of the test, the temperature of the steel sheet during sunlight irradiation at midday was measured under the same conditions, and as a result, the surface temperature of the steel sheet of the control increased to 80 ° C. The steel plate used only rose to 70 ° C.

The results of the outdoor exposure test two years later showed that the steel sheet using the pigment coated with the thin film had an initial gloss of 70.
%, And ΔE was 3. In contrast, the control had a gloss reduced to 60% of the initial gloss and a color difference of 5 at ΔE.

Such a difference appeared because, in the case of using the pigment coated with the thin film, the dry coating film of aluminum oxide has a function of reflecting the heat rays from the surface, so that the temperature rise of the film layer can be suppressed, It is considered that this was able to prevent the progress of thermal deterioration and suppress discoloration.

Next, examples of the present invention in which the thin film coating technique is applied to a pigment for a color toner will be described.

[Example 1] Japanese Patent Application No. 61-93223 (filed on April 24, 1986, coated with fine powder) was coated on the surface of 5 g of commercially available phthalocyanine blue No. 700 manufactured by Toyo Ink Co., Ltd. Method and equipment)
Was coated with titanium oxide by a sputtering apparatus shown in FIG. The sputtering conditions were as follows: using a titanium target, output 500W, pigment temperature 50 ° C,
The atmosphere was an argon gas containing 30% oxygen, and the treatment was performed for 1 hour. As a result, a coating of titanium oxide having a thickness of about 50 ° was applied to the surface of the pigment.

5 g of the obtained product of the present invention, 100 g of a polystyrene resin, and 10 g of a styrene copolymer containing 10% dimethylaminoethyl methacrylate were mixed and pulverized by a ball mill, melt-kneaded by a roll mill, cooled, and then coarsely pulverized by a hammer mill. Then, it was pulverized with a fluid jet mill manufactured by Nippon Pneumatic Co., Ltd. The obtained fine powder was classified, and 1 to 20 μm was selected as a toner. 90 g of a carrier (reduced iron powder manufactured by Dowa Iron Powder Co., Ltd.) was mixed with 10 g of this toner to prepare a developer. When a blue negative latent image on a zinc oxide photosensitive paper was developed using this developer, an extremely clear cyan-positive image was obtained. From these results, it was found that the dispersibility of the pigment was improved as compared with the conventional product having no dry coat as in the present invention, and the charging characteristics of the toner were considerably improved.

Example 2 The same color toner as in Example 1 was prepared except that a dry coat of an oxide of aluminum or silicon was applied instead of the titanium oxide of Example 1. In this case, as in Example 1, good results were obtained.

As described above, the present invention dry-coats a thin film of a metal or a metal oxide made of titanium, aluminum, silicon or one or a combination of two or more of these oxides on the surface of a pigment powder. In other words, the adoption of a new pigment modification method imparts functionality such as electrostatic properties to the pigment powder itself without impairing the properties of the original pigment substance. Therefore, according to the present invention, the charge amount distribution is uniform and stable, the initial characteristics are maintained even when used for a long period of time, and the charge characteristics are not changed. This makes it possible to provide an excellent color toner pigment which is not affected.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-56-130469 (JP, A) JP-A-62-100770 (JP, A) JP-A-61-16068 (JP, A) JP-A-62 250172 (JP, A) Fully open 1987-6-15937 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09C 1/00-3/12 G03G 9/09

Claims (1)

(57) [Claims] 1. A dry coating of a metal consisting of titanium, aluminum, silicon or one or a combination of two or more of these oxides or a metal oxide thereof having a thickness of 10 to 100 ° is sputtered on the surface of a pigment powder. Pigment for color toner applied by the method.