JPS63318568A - Electrically conductive supporting body - Google Patents

Abstract

PURPOSE:To obtain a good conductive supporting body applicable to an electrostatic recording body by forming on one or both sides of a base material a conductive layer containing a binder and a fibrous potassium titanate coated with a metal oxide on the surface. CONSTITUTION:The conductive layer to be formed on one side or both sides of the base material contains the binder and the fibrous potassium titanate coated with the metal oxide on the surface in a solid weight ratio of (3:7)-(7:3), thus permitting the obtained conductive supporting body to be reduced in variance of surface resistivity and volume resistivity due to environmental humidity, to exhibit always adequate resistivity, consequently, a good image quality to be obtained even under high or low humidity, adequate resistivity to be obtained by using a small amount of coating material containing conductive whiskers, accordingly, economical merit to be obtained, and further, the obtained supporting body to be enhanced in smoothness, whiteness, tone, property like paper, or the like and improved in the barrier effect of the conductive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive support used in particular for electrostatic recording media.

A conductive support used for electrostatic recording materials such as electrostatic recording paper, electrostatic transfer paper, and current-carrying recording paper is a base material such as paper with a conductive layer (low resistance layer) provided on one or both sides. be.

The materials for this conductive layer include (1) a polymeric ionically conductive material (polymer electrolyte), +2) a mixture of an inorganic ionically conductive material and a polymeric electrolyte or a binder, and an electronically conductive material (3). ) Metal powder or (4) a mixture of a conductive oxide such as conductive zinc oxide and a polymer electrolyte or a binder are known.

However, the resistance value of the ion conductive materials 1) and (2) varies greatly depending on moisture and (relative humidity), especially 154R.
When the humidity is low, such as H or less, it exhibits high resistance and has the disadvantage that no image is produced during recording. Furthermore, although electronically conductive materials have a reduced resistance value dependence on humidity, the metal powder (3) has a drawback in that the resistance value varies significantly depending on dispersion and application conditions. Furthermore, conductive zinc oxide (4) has a low resistance value when used alone, but when mixed with a binder, the resistance value increases.
0 g/m''.For this purpose, conductive zinc oxide is used as a base material, for example.

The paper becomes discolored and lacks paper-like properties, reducing its commercial value, and since conductive zinc oxide is expensive, the manufacturing cost of the conductive support increases. In a mixture of conductive zinc oxide and polymer electrolyte, if the proportion of conductive zinc oxide is high, the barrier property (permeation resistance of the conductive support when applied with a dielectric layer forming liquid) deteriorates and the dielectric layer is insufficient. not formed,
Image roughness, white spots, and missing fine lines are observed. Furthermore, when the proportion of conductive zinc oxide decreases, the humidity dependence of the resistance value increases, so that the resistance value deviates from the appropriate range in low-humidity and high-humidity environments, resulting in a decrease in image density and poor image quality.

The present invention provides a conductive support having a conductive layer containing fibrous potassium titanate whose surface is coated with a metal oxide and a binder in a solid content ratio of 3 to 7:3 on one or both sides of the base material. It is.

Examples of the base material used in the present invention include paper, plastic sheets, synthetic paper, and the like.

Fibrous potassium titanate whose surface is coated with metal oxide (
Conductive whiskers (hereinafter referred to as conductive whiskers) are obtained by doping fibrous potassium titanate with aluminum, chromium, tin, antimony, indium, etc., and have a chemical composition of 2.
0.n'I"102x1 The average fiber length is 5 to 30 μm, the fiber diameter is 0.1 to 1 μm, and the specific resistance is 1 to 106 Ω.

This conductive whisker is easily available as a commercial product.

As a binder, polyvinyl alcohol (PVA'
), starch, carboxymethyl cellulose, hydroxyethyl cellulose, etc.

The mixing ratio (P/B ratio) of the conductive whiskers and the binder needs to be 5:7-y7:5 in terms of solid content ratio. When the p/B ratio is smaller than this, the conductive resistance value becomes high at low humidity, and ghosts are likely to occur in an electrostatic recording medium using a conductive support at high humidity. Moreover, if the P/B ratio is larger than this, the adhesion of the conductive layer to the base material will be insufficient, and the resistance value will decrease in high humidity, which is also unfavorable from the viewpoint of barrier properties.

When producing the conductive support of the present invention, first, conductive whiskers and a binder are dispersed or dissolved in a solvent. As the solvent, water, methanol, ethanol, propatool, toluene, acetone, methyl ethyl ketone, ethyl acetate, etc. are used. If necessary, a dispersant such as a polyacrylate or a polystyrene salt, and an antifoaming agent such as an alcohol may be added to the dispersion liquid.

Next, the dispersion is applied to one or both sides of the substrate using an air knife coater, roll coater, wire bar coater, spray coater, fountain coater, trailing coater, reverse roll coater, or dip coater, and then dried to form a conductive layer. Then, the conductive support of the present invention is obtained.

The coating amount (solid content adhesion amount) of the conductive layer is 2 to 15. lit/
m" is preferable. If the coating amount is less than this, an appropriate resistance value may not be obtained. Also, if the coating amount is greater than this, no particular improvement in the effect will be observed. Conductive/electrical layer may be formed on one side of the base material, but forming it on both sides is advantageous in that curling and conductivity of the support are good in various environments.

The conductive support of the present invention exhibits little variation in surface resistance and volume resistivity due to environmental humidity, and always exhibits an appropriate resistance value. Therefore, in the electrostatic recording medium of the present invention in which a dielectric recording layer is provided on a conductive support, good image quality can be obtained even in high-humidity and low-humidity environments.

Furthermore, the use of conductive whiskers is economically advantageous because an appropriate resistance value can be obtained with a smaller amount of coating than conventional conductive components. Further, the conductive support of the present invention has excellent smoothness, whiteness, color tone, paper-like properties, etc., and the conductive layer has good barrier properties.

The conductive support of the present invention can be used as a support for electrophotographic paper or other lengths of recording paper in addition to electrostatic recording media.

Example 1 Conductive whisker (Dentor WK-30 manufactured by Daibutsu Kagaku Co., Ltd.)
0) and 112 g of water were mixed, and dispersed for 20 minutes using a homomixer using polyacrylate as a dispersant. To this, 320 g of a 15% PVA aqueous solution was added, and the mixture was further dispersed for 5 minutes. This dispersion was applied to one side of high-quality paper (base material) with a basis weight of 5 Qg/m2 and dried, with a coating weight of approximately 7jj/m2.
A conductive support was prepared by applying a conductive layer of m''.

Example 2 22.5% PVA instead of 15% PVA aqueous solution
A conductive support (coating amount: 8.!i'/m2) was produced in the same manner as in Example 1 except that an aqueous solution was used.

Example 3 A conductive support (coating amount: 69/m2) was produced in the same manner as in Example 1 except that a 10% PVA aqueous solution was used in place of the 15% PVA aqueous solution.

Example 4 A conductive support having conductive layers on both sides of the base material was produced in the same manner as in Example 1. The amount of coating on each side is approximately 7 g.
/ m2 and 49/m2.

Comparative Example 1 48 g of conductive zinc oxide and 112 I of water were mixed, and dispersed for 60 minutes using a homomixer using polyacrylate as a dispersant. To this, 620 I of a 10% PVA aqueous solution was added.
Dispersion was continued for an additional 5 minutes.

This dispersion was coated on one side of wood-free paper with a basis weight of 50 g/m" and dried to form a conductive layer with a coating weight of 20 g/m" to produce a conductive support.

Comparative Example 2 48 g of calcium carbonate and 112 g of water were mixed, and dispersed for 30 minutes using a homomixer using polystyrene as a dispersant. To this was added 620 I of 10 tivolivinylpenzyltrimethylammonium chloride aqueous solution, and the mixture was further dispersed for 5 minutes. did. This dispersion was coated on one side of a high-quality paper with a basis weight of 50 g/m2 and dried to form a conductive layer with a coating weight of 597 m2, thereby producing a conductive support.

Comparative Example 3 A 20% polyvinylbenzyltrimethylammonium chloride aqueous solution was applied to one side of a high-quality paper with a basis weight of 50 g/m2 and dried to form a conductive layer with a coating weight of 5 g/m2, and the other side was coated with Comparative Example 2. Conductive layer similar to (coating amount: 5 g/m
”) to produce a conductive support.

Test Examples The conductive supports of Examples 1 to 4 and Comparative Examples 1 to 3 were conditioned for 4 hours or more in the atmosphere shown in the table below and then measured using a ring method using a measuring device.

Also, 100g of 40% toluene solution of acrylic resin, 20g of calcium carbonate. A mixture of li+ and 8゜l of toluene was dispersed for 1 hour using a homomixer, and this dispersion was used in Examples 1 to 2.
After coating on the conductive layer of the support of Comparative Examples 1 to 4 and Comparative Examples 1 to 3, the dielectric layer was dried, and a dielectric layer having a coating amount of 517 m2 was provided to produce an electrostatic recording material. Images were formed on these electrostatic recording materials by facsimile, and the image density was measured. As a facsimile, the linear density is 161/II! A commercially available product using a one-component carrier restraint was used. Image density was measured using a Macbeth reflection densitometer (RD514) for all black recordings. The records evaluated all-black drawings and line drawings. The results are shown in the table below. The ○ mark in the table indicates that there is no poor image quality such as roughness in all-black drawings or omissions in line drawings. Moreover, a - mark indicates that evaluation is impossible or defective. Note that the density in the table means the image density of the electrostatic recording medium.

Claims (1)

[Claims] On one or both sides of the base material, fibrous potassium titanate whose surface is coated with metal oxide and a binder are added at a solid content ratio of 3:7.
A conductive support having a conductive layer containing a ratio of ~7:3.