JPS6350847A - Electrostatic recording film - Google Patents

Abstract

PURPOSE:To prevent reduction in the electrical conductivity of an electrically conductive layer during the coating of a dielectric layer by forming the electrically conductive layer with electrically conductive metal oxide particles of <=0.5mu average particle size and a water soluble polymer and the dielectric layer with a polymer soluble in an org. solvent. CONSTITUTION:When a dielectric layer is coated on an electrically conductive layer with an org. solvent, a water soluble polymer which inhibits the penetration of the org. solvent is used as a binder in the conductive layer. An electrically conductive substance used in the conductive layer is an electrically conductive crystalline metal oxide and the average particle size of the metal oxide is regulated to <=0.5mu, preferably <=0.2mu so as to maintain transparency. The metal oxide may be ZnO, SiO2, SnO2 or a composite oxide thereof. A support used is a transparent plastic film such as a film of polyethylene terephthalate or polycarbonate. The electrically conductive layer may be directly coated on the support or the surface of the support may be treated by corona discharge or low discharge or with a flame or UV.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic recording film. Recently, with the development of CAD and CAM, the output is increasingly being produced using electrostatic recording. The present invention relates to an electrostatic recording film using a plastic film as a support.

[Conventional technology]

Electrostatic recording films are composed of three layers: a support, a conductive layer, and a dielectric layer. Conventionally, the conductive layer is made of a polymer electrolyte such as a cationic polymer or anionic polymer, an ionic surfactant, or a moisture absorbent. It was a polymer with inorganic ions added to it.

However, the conductivity of these ionic materials is dependent on humidity, and when the humidity is low, the conductivity decreases and the material cannot function sufficiently as a conductive layer, making the electrostatically recorded image unclear.

For this reason, an electron conductive material that does not depend on humidity changes was considered for the conductive layer. Tokukai Shoj! -73j4tJj discloses the use of polyaniline materials,
This product is colored and is not preferred. Tokukai Akira! /-2
6/G0, Tokukai Akira! 2-//322 yen issue, Tokukai Sho! !
-1j! No. 90 describes that conductive metal oxide particles are dispersed in a binder and applied to paper or the like. However, the conductive metal oxide particles in the above-mentioned patent have a size of several microns and cause light scattering, so they cannot be applied to transparent films. By improving this, JP-A-Shoj4-/gJ4t4tJ No. 1
It is θ, . It is described that both conductivity and transparency can be satisfied by using conductive metal oxide particles of 5 μm or less as a conductive layer.

However, when fine particles of a conductive metal oxide are dispersed in a binder and used in the conductive layer, the conductivity is often lowered due to the effect of coating the dielectric layer. In other words, when the coating solvent of the dielectric layer interacts with the binder of the conductive layer, when the dielectric layer is coated, the solvent in the coating solution penetrates into the conductive layer, reducing the conductivity of the conductive layer from its initial value. It often happens. This tendency becomes more remarkable as the conductive metal oxide becomes finer particles.

[Purpose of the invention]

The object of the present invention is to prevent the above-mentioned drawback from decreasing the conductivity of the conductive layer during application of the dielectric layer.

[Means for solving problems]

It has been found that the above problems can be solved by using a water-soluble polymer as a binder for the conductive layer and an organic solvent-soluble polymer for the dielectric layer.

That is, it has been found that when the dielectric layer is coated with an organic solvent, the problem can be solved by using a water-soluble polymer as a binder for the conductive layer, which can prevent penetration of the organic solvent.

The water-soluble polymer of the present invention is produced by Tokkosho! There is no need to have ionic conductivity as described in ``L''-, 27 Gutada, and there is no need to add electrolytes such as salts to the water-soluble polymer layer.On the contrary, it is not necessary to add electrolytes such as salts to the water-soluble polymer layer. Adding a large amount deteriorates the stability of the dispersed fine particles, which is not preferable.

Examples of water-soluble polymers used in the present invention include:
Polyvinyl alcohol, polyacrylic acid, polyacrylamide, polybitroxyethyl acrylate, polypyrrolidone, water-soluble polyester, water-soluble polyurethane, water-soluble nylon, gelatin, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, or derivatives thereof, etc. , is a polymer whose main components are these. These water-soluble medium or crosslinking agents may be added.

The conductive substance used in the conductive layer of the present invention is preferably a conductive crystalline metal oxide, and in order to maintain transparency, the average particle size is 0. ．． 5
It is preferably 0.2 μ or less, preferably 0.2 μ or less. ZnO is a conductive crystalline metal oxide.

5i02.5n02, TiO2, Al2O3, In2
O3.

These are MgO, BaO, MoO3, etc., or composite oxides thereof.

The support used in the present invention is a transparent plastic film, such as polyethylene terephthalate, polycarbonate, cellulose triacetate, polyether sulfone, polyvinyl chloride, polystyrene, polyethylene, polypropylene, and the like.

The above conductive layer may be applied directly to the support, or the surface of the support may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet treatment, or radiation treatment, or adhesive may be applied between the conductive layer and the support layer. For example, a layer of vinylidene chloride copolymer, styrene-butadiene copolymer, vinyl chloride copolymer, vinyl acetate copolymer, acrylic ester copolymer, polyester, polyurethane, gelatin, etc. is provided as a layer. It's okay.

Since the dielectric layer must have insulating properties, it is not preferable to use ionic polymers or polymers that dissociate upon absorption of moisture, and it is necessary that the dielectric layer does not contain large amounts of ionic substances. Soluble polymers are preferred.

Organic solvent-soluble polymers include vinyl chloride, vinylidene chloride, styrene, methylstyrene, butazine, alkyl esters of acrylic acid (alkyl groups from C1 to C4'l), alkyl esters of methacrylic acid (alkyl groups from CI to C4). ), homopolymers such as vinyl acetate, acrylonitrile, soptylene, allyl acetate, soluble polyesters, polycarbonates, cellulose derivatives such as ethyl cellulose, cellulose acetate, cellulose propionate, polyvinyl butyral, polyvinyl formal, etc. I can go crazy.

Examples of coating solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ethers such as tetrahydrofuran and dioxane, esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate, and chlorine such as dichloromethane and dichloroethane. Examples include hydrogenated hydrocarbons, alcohols such as methanol, ethanol, and zolopanol.

The thickness of the dielectric layer is from /μ. It is preferable to add a matting agent of about 5 μm, and preferably about 3 μm to /θμ.

Examples will be described below, and the surface resistivity was measured using parallel electrodes and an electrometer manufactured by Keithley.
Relative humidity at 3°C! The measurement was carried out in an atmosphere of θ.

Also, when applying the dielectric, both sides of the conductive layer should be approximately 10m/
This area was used to determine whether the resistivity of the conductive layer changes when the dielectric layer is applied.

Example 1 A biaxially stretched and heat-set polyethylene terephthalate film with a thickness of 100 μm was subjected to glow discharge treatment, a liquid having the following composition was applied as a conductive layer, and the film was dried at /300C for 70 minutes.

Gelatin /! (Parts by weight) Tin oxide doped with antimony having an average particle size of 0.2μ (the amount of antimony is j times the amount of tin oxide) j6(1), goudichlor-6 monohydroxy-8- Natrilam salt of triazine O,O3( # )water
1000 (#) On top of this layer, a dielectric layer was formed using a dry film with the following composition. ．． It was applied to a thickness of 5μ and dried at 1so0c for 10 minutes.

Byron (manufactured by Toyobo)! 0 (parts) Rosin ester (manufactured by Arayo Kagaku) COI Methyl ethyl ketone 700 1 Cyclohexanone 100 #Ethyl acetate
-001 The surface resistivity is shown in Table 1.

Example 2 A biaxially stretched and heat-set polyethylene terephthalate film with a thickness of 100 μm was subjected to a corona discharge treatment, and a liquid having the following composition was applied as an undercoat layer and dried at 3θ0C for 70 minutes.

Vinylidene chloride/ethyl acrylate/acrylic acid/copolymer latex (copolymerization ratio/j//θ/!, solid content 2!chi) -〇 (parts by weight) Water
10θ0 (I 2 ) Then, a conductive layer and a dielectric layer were sequentially coated in the same manner as in Example.

The surface resistivity is shown in Table 1.

Comparative Example A biaxially stretched and heat-set polyethylene terephthalate film having a thickness of 10θμ was subjected to a corona discharge treatment, and a liquid having the following composition was applied as a conductive layer, followed by drying at 300C for 70 minutes.

Vinylidene chloride/ethyl acrylate/acrylic acid copolymer latex (coelectrolyte ratio r!/10/!, solid content co!) t, to (parts by weight) antimony-doped tin oxide with average particle size θ, 2μ (The amount of antimony is j to tin oxide) jO(I) water
1000 Then, a dielectric layer similar to Example/ was applied.

Table 1 shows the changes in surface resistivity.

Table 1 As can be seen from Table 1, when a water-soluble polymer was used as the binder, almost no change in surface resistivity was observed even after applying the dielectric layer, but when a vinylidene chloride copolymer was used. The effect was recognized, with an increase of about 9 digits.

Claims (1)

[Claims] In an electrostatic recording film comprising at least a substantially transparent support, a conductive layer, and a dielectric layer, the conductive layer comprises conductive metal oxide particles with an average particle size of 0.5 μ or less and a water-soluble polymer, and An electrostatic recording film characterized in that the body layer is made of an organic solvent-soluble polymer.