JPS585369A - Preparation of electrically conductive pigment - Google Patents

Abstract

PURPOSE:To prepare an electrically conductive pigment useful for imparting an antistatic property to recording material, plastic film, etc., by applying a soln. of an In or Sn compd. on the surface of heated pigment to cover pigment particles with an electrically conductive film consisting mainly of In2O or SnO2. CONSTITUTION:An aqueous or alcoholic soln. of an In compd. (e.g. InBr3) or an Sn compd. (e.g. SnCl4) is sprayed over the surface of pigment (e.g. baryte powder) kept at 300 deg.C or higher, followed by heating for several tens of seconds to several hours to form a coating film of electrically conductive substance consisting mainly of In3O or SnO2. EFFECT:The pigment has an electrical conductivity not affected by changes in humidity etc. and is useful for electrophotographic sensitive paper, static recording material, etc. which produce images of consistent quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to electrically conductive processing on the surface or inside of a support of recording materials such as electrophotographic paper, electrostatic recording paper, and electrostatic coloring paper, and is also used for electroconductive processing of the surface or inside of a support of recording materials such as electrophotographic paper, electrostatic recording paper, and electrostatic coloring paper. This invention relates to a method for producing conductive pigments useful for prevention.

Recording materials such as electrophotographic photosensitive paper, electrostatic recording paper, and electrochromic paper are usually created by coating or impregnating a conductive substance on the surface or inside of an insulating support such as paper. However, it was produced by providing a photoconductive layer, a dielectric layer, and a coloring layer on the support. In this case, as the conductive substance, an ion conductive conductive material such as a polymer electrolyte or an inorganic salt, or an electronic conductive conductive material such as a conductive inorganic metal compound has been used.

Among these, the conductivity of those using ion-conducting conductive materials is greatly affected by changes in humidity.

That is, the conductivity is high at high humidity, and the conductivity is low at low humidity. For example, in the above-mentioned recording materials, this change in conductivity affects the recording quality, and
(At low humidity below IRH or high humidity above 80% RH, only a very unclear image could be recorded, making it unusable for practical use.Furthermore, with an offset master in which a photoconductive ZnO layer was provided on the support, Since the ion conductive conductive material used on the surface or inside of the support is hydrophilic,
The ZnO layer was peeled from the support or torn due to absorption of the dampening water. In addition, electrically conductive color recording materials that utilize color development due to heat generation when electricity is applied, color development due to injection of electrons or electrophilic electrolyte, and color development due to electrolytic action have low conductivity and are not practical.

On the other hand, conductive inorganic compounds doped with impurities, such as Al't, are used as conductive materials that are relatively less affected by humidity.
When doped ZnO is applied to the recording material,
Since the electrical resistance is low, the above-mentioned electrochromic recording material is not particularly practical. In addition, when used for electrophotography or electrostatic recording paper, the conductivity is low and a large amount (at least 10 g//m2) must be used for the paper support, which may impair the naturalness of the paper or damage the recording paper. It had the disadvantage of increasing the weight.

The purpose of the present invention is to solve the above-mentioned conventional drawbacks and to provide a method for producing an inexpensive conductive pigment used in recording methods such as electrophotography, electrostatic recording, and electrochromic printing. It is something to do.

That is, the present invention is characterized in that a solution containing an indium compound or a tin compound as a main component is attached to a heated pigment surface and dried, and a conductor containing indium oxide or tin oxide as a main component is attached to the pigment surface. This is a method for producing conductive pigments.

Pigments used in the present invention include pallite powder, precipitated calcium sulfate, carbonate, lime carbonate powder, precipitated calcium carbonate, hexastomy, asbestos, clay, silica, finely divided silicic acid, diatomaceous earth, and tartar. , basic magnesium carbonate, alumina white, satin white, zinc oxide, lead white,
Basic lead sulfate, lead sulfate, lithopone, titanium oxide, antimony oxide, etc.

To deposit inzoum oxide on the surface of these pigments,
InBr3, InCl3, InI3, In(No5)5
-Aqueous solutions of In20, In2(SO4)3, etc., In(
OH) A solution of an indium compound such as an alcoholic solution of 3, a dilute sulfuric acid solution of In(ros)s, and a dilute acid solution of 2■n206/3S02I8H201゛9 becomes ヱ・□rum.

When a solution in which a tin compound is further added to the indium compound solution is used, tin is doped into the indium oxide adhering to the pigment surface, and the conductivity is further improved. The amount of tin added is snc14/I nC (13
~5 wt% is preferred.

To attach tin oxide to the pigment surface, S n C11
2, aqueous solution of S n C14, S n SO 4, etc.
A tin compound solution such as an alcoholic solution of S n (OH) 2 may be attached to the surface of the pigment kept at a high temperature of 300° C. or higher. At this time, if an antimony compound or a bismuth compound is added to the tin compound solution, even better conductivity can be obtained. The amount of antimony or bismuth added is S b Cls/S n C12, BIC13/'
It is preferably 1 to 7 wt% in terms of snC12.

In any of the above cases, the heating time after solution deposition depends on the type of pigment, the type of compound to be attached to the pigment surface, and the conductivity of the pigment of the present invention, which is not affected by changes in humidity.
When applied to recording materials such as electrophotographic paper, electrostatic recording paper, and electrochromic paper, stable recorded images can always be obtained. or,
It is also useful for preventing static electricity when applied to polymer films, etc. The manufacturing method is extremely simple, and the conductive pigment can be obtained at low cost.

Examples are shown below.

In an example, 500 g of titanium oxide was heated to 500°C in an electric furnace, and without stirring, InC13/In20 (n~35) 50
A solution consisting of 200 g of titanium dioxide and 200 l of water was sprayed little by little so that the temperature of titanium dioxide did not fall below 300°C. After spraying was completed, the mixture was heated for 10 minutes with stirring and allowed to cool naturally. After molding the pale yellow pigment with inzoum oxide adhered to the surface obtained by applying a pressure of 150 kg//crn2, the pressure was released, and electrodes were provided by vapor-depositing aluminum on both ends, and the temperature and humidity conditions were as follows. After being left for one week, a test similar to the above was conducted on conductive ZnO whose electrical resistance had been doped with Al'f, and the following results were obtained.

20℃ 15%RH IXIOΩ・020℃ 90
%RH 5×10Ω·- From the results, the titanium dioxide pigment to which indium oxide of the present invention was attached had a lower resistance value but was stable compared to the conventional A7-doped ZnO.

Example 2 In Example 1, 1.
When a conductive pigment was prepared in the same manner except that 5 g was added and tested, the following results were obtained.

20℃ 15%RH3X1oΩ'ff120℃ 90%
RH5X100.z From the above results, it can be seen that conductivity is increased by doping Sn into indium oxide.

Example 3 Precipitated calcium carbonate 500.9 was heated to 600°C in an electric furnace, and without stirring, a solution consisting of 250 g of 5nCN and 300 g of methanol was added little by little so that the temperature of the precipitated calcium carbonate did not fall below 400°C. I passed it. After completion of the heating, the mixture was heated for 20 minutes with stirring and allowed to cool naturally. The pigment with tin oxide attached to the surface thus obtained was subjected to the same test as in Example 1, and the following results were obtained.

20°C 15%RH8X10”Ω°α 20°C 90% RHIXIQ Ω・α Example 4 Conductive carnoum carbonate pigment obtained in Example 3 80
g1 polyvinyl acetate latte, couscous (solid content 40 g) 100
g, water 180I was mixed and dispersed, and the basis weight was 559/rrI2
A conductive layer was formed by coating both sides of high-quality paper so that the solid content was 4 g on one side, and the surface electrical resistance was measured after being left for 8 hours under the following temperature and humidity conditions. We obtained the following results.

20℃ 15℃ RH4×108℃ 20℃ 90℃ RH9×10℃Meanwhile, in the above, instead of conductive calcium carbonate, A
A conductive layer was formed on high-quality paper in the same manner except that conductive ZnO doped with l was used, and the surface electrical resistance was measured, and the following results were obtained.

Hydrophobic silica fine powder 20g acrylic resin (manufactured by Mitsubishi Rayon @l 100g Product name Diamond) A mixed dispersion of 2'00 ml of toluene (Narl LR-81) was applied to give a dry weight of 5797 m2 to obtain two types of electrostatic recording paper.

All of these electrostatic recording papers 20℃15RH and 30℃85
%RH environment for 8 hours, product name RIFAX -
On electrostatic recording paper 60OS manufactured by Ricoh Co., Ltd., almost no image was formed in an environment of 20° C. and 15% RH.

Patent applicant Ricoh Co., Ltd. Representative Patent Attorney Hidetake Komatsu -54'

Claims (1)

[Claims] 1. Conductivity characterized by attaching a solution containing an innoum compound or a tin compound as a main component to the heated pigment surface and drying it, and adhering a conductor containing indium oxide or tin oxide as a main component to the pigment surface. Pigment manufacturing method.