JPS58223152A - Electrostatic recording material - Google Patents

Abstract

PURPOSE:To enhance adhesions between a support and each layer, and mechanical strength, etc., by forming a conductive layer consisting of a conductive fine powder and a binder resin contg. a proper amt. of same resin as used for a dielectric layer or a same type resin as the latter resin and forming the dielectric layer on this layer on a support made of plastic film or the like. CONSTITUTION:When a conductive fine powder, such as carbon black, Al, Ni, or the like metallic powder, or conductive oxide, and a binder resin are mixed and formed on a polyester film or the like to form a conductive layer, and a proper amt. of a same or same type resin as the resin used for the dielectric layer to be formed on the conductive layer is mixed with the binder resin. For example, when polyester resin is used for the dielectric layer as a high resistance resin, the same or similar polyester resin is used for the conductive layer. The electrostatic recording material thus obtained is high in adhesions between the support and the conductive layer, the conductive layer and the dielectric layer, resistant to peeling, etc., and superior in durability. It forms an electrostatic image by using a stylus electrode.

Description

[Detailed description of the invention] The present invention relates to an electrostatic recording medium particularly suitable for repeated use.

As an electrostatic recording material, a conductive layer made of a metal such as A-e, Zn, or a European compound thereof, or a conductive fine powder such as carmen black, conductive zinc oxide, etc., and PVA are used on a support such as a plastic film.

The conductive layer is made self-supporting by providing a conductive layer mainly composed of a water-soluble resin, or by incorporating conductive fine powder into the support, and further oxidizing the conductive layer. It is known to have a dielectric layer mainly composed of pigments such as titanium and zinc oxide, and high-resistance resins such as polystyrene and silicone resin. When these electrostatic recording materials are repeatedly used in a belt form in a transfer electrostatic recording device, they come into contact with needle electrodes for a long time, so the abrasion resistance of the surface, that is, the tIijt layer, and therefore the surface hardness, are particularly important. and adhesion to the conductive layer. Here, the surface hardness of the dielectric layer depends on the pigment and high-resistance resin used for the dielectric layer, and the adhesiveness with the conductive layer depends not only on the resin of the dielectric layer but also on the resin of the conductive layer. On the other hand, the thickness of the dielectric layer is generally several βm to several tens of μm.
However, in order to obtain a good quality image using a needle electrode, 15μ
It is preferable that the thickness be less than m.

However, when the vIt layer is made thin like this, it tends to become brittle, especially when the surface hardness is increased, and its adhesion with the conductive layer is also poor, so the dielectric layer may be scratched or cracked during repeated use as an electrostatic recording material. There were drawbacks such as delamination and delamination.

An object of the present invention is to provide a durable electrostatic recording material with excellent mechanical strength that eliminates the drawbacks caused by the brittleness of conventional dielectric layers and adhesion between conductive layers.

The electrostatic recording material of the present invention is an electrostatic recording material in which a conductive layer containing conductive fine powder and resin as main components is provided on a support, and a conductive layer containing pigment and high-resistance resin as main components is further provided on the support. In the body, at least a portion of the resin for the conductive layer is fermented! It is characterized by using the same resin or the same type of resin as the resin used in the invention.

The material for the conductive fine powder used in the conductive layer of the present invention is Kajime/Black; In, ca.

Any Or, Ni+ Ag, Au, a
Examples include gold ellipses such as n and an; conductive zinc oxide, and conductive titanium oxide. The amount used is 1 layer of resin.
5 to 600 parts by weight per 00 parts by weight is suitable.

On the other hand, resins used for the conductive layer include resins that are the same or of the same type as the high-resistance resins used for UtIm resins, such as silicone resins, alkyd resins, thermosetting polyurethanes, thermosetting acrylic resins, epoxy resins, and thermosetting resins. Thermosetting resins such as curable polyester, urea resin, melamine resin, pheno-V resin, polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride,
Examples thereof include thermoplastic resins such as polyvinyl acetate, thermoplastic polyurethane, thermoplastic polyester, boria dendritic resin, polycarbonate, thermoplastic acrylic resin, and copolymers thereof.

Other low resistance resins such as PVA and CMC.

Methyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone, starch, casein, etc. may be used in combination.

The appropriate amount of these low resistance resins to be used is 50 parts by weight or less per 100 parts of high resistance resin. In the present invention, resins of the same type refer to those having a structure in the main chain, side chain, or crosslinking part that can be called by the same name in the classification name of the resin.

Next, fine powders of silica, zinc sulfide, calcium charcoal, titanium dioxide, aluminum oxide, etc. are ground up as pigments used in the process. Further, specific examples of the high-resistance resin used for the d-electrolayer are as described above, but thermosetting resins are preferred for the reasons described later. The amount of pigment used is W
s Conductive layer 5-300″IL per 100 parts by weight of high-resistance resin
Sunbe is suitable.

To produce the electrostatic recording material of the present invention, conductive fine powder is dispersed in a resin layer liquid containing the same or the same type of high-resistance resin as the conductive layer on a support such as paper or zotsu snack film. After applying the liquid and drying it, if a thermosetting resin is used, cross-link and harden it by heating to form a conductive layer with a thickness of about 0.5 to 30μ, and then disperse the pigment in a high-resistance resin solution. The resulting dispersion is applied and dried, and if a thermosetting resin is used, heat treatment is performed as described above to form a dielectric layer with a thickness of about 2 to 30 μm.
Just set it up. Note that if a thermoplastic resin is used as the high-resistance resin and the fractional dispersion for Mum is coated with a wire coater, roll coater, or other conventional means, the thermoplastic resin in the lower layer 4 = t - will become the dispersion liquid. If a thermoplastic resin is used, it is necessary to use a method that does not cause such damage, such as a spray method, to apply the bulking liquid for electrical protection. In the case of thermosetting resins, there are no such restrictions on distribution.

Examples of the present invention are shown below. In addition, all sections] are part of the section.

Example 1 A solution containing 100 parts of methyl ethyl ketone was dispersed in a ball mill for 2 hours, and then 10 parts of Coronate L (isocyanate sol polymer made by Nippon Polyurethane) was added and dispersed for 10 minutes.
A conductive layer was provided on a polyester film having a thickness of 00 μm by coating and drying so that the film thickness after drying was 15 μm, and heating at 100° C. for 1 hour. Next, a liquid formulation consisting of 40 parts of methyl ethyl ketone and 100 parts of coronate was dispersed using ultrasonic waves for 10 minutes, and this was sprayed onto the conductive layer for 5 minutes to give a film thickness of 10 μm after drying. After drying, the solution was further heated to 100°C. A conductive layer was formed by heating for 1 hour.

The surface hardness of the electrostatic recording material thus obtained was 6 on the lead hardness scale.
It was H. Also, Scotch Mending Teso [Sumitomo 3]
Made by M ■! In a peel test in which the dielectric layer was pasted on the surface of the recording medium and then peeled off, no peeling of the dielectric layer was observed.

Next, the electrostatic recording material is processed into an endless belt shape, and this is set in a transfer-type electrostatic recording device that has one cycle of latent image formation (using needle electrodes), development, transfer, static elimination, and cleaning, and repeated tests are carried out. Even after repeating this process 20,000 times, a high-quality image equivalent to the initial image was formed. At this time, no peeling or scratches of the first layer were observed on the electrostatic recording material.

Comparative Example 1 An electrostatic recording material was produced in the same manner as in Example 1 except that the conductive layer was provided by vapor deposition of indium oxide. Since the conductive layer of this recording medium has the same composition as in Example 1, the surface hardness is as in Example 1.
However, in the peel test, some peeling occurred, and in the repeated test, the dielectric layer was damaged after about 2,000 repetitions, and part of the I-electric layer peeled off after 5,000 repetitions. Ta.

Example 2 A liquid formulation consisting of 30 parts and 150 parts of methyl ethyl ketone was dispersed in an &-/rail for 1 hour, and this was applied and dried on a polyester film with a thickness of 100 IIrn to a film thickness of 20 Ilm after drying. A conductive layer was provided. Next, a solution containing 20 parts of zinc sulfide imitation powder, 10 parts of Niron 200, and 100 parts of methyl ethyl ketone was dispersed in the same manner as above, and sprayed onto the conductive layer so that the film thickness after drying was 8 μm. A dielectric layer was provided by coating and drying.

The electrostatic recording material thus obtained had a surface hardness of 4H, no peeling was observed in the peel test, and the same good results as in Example 1 were obtained in the repeat test after 10,000 repetitions.

Comparative Example 2 A liquid with a formulation of 400 parts of IY Kukazei's 1096 water bath solution was whole-milled, coated on a 100 μm thick JE lyester film to a film thickness of 7 μm after drying, and dried to obtain a conductive material of 1.
- was provided, and the same electrostatic charge +m as in Example 2 was provided thereon to obtain an electrostatic recording material.

This electrostatic recording material had the same surface hardness and peel test results as Example 2, but in the repeated test, scratches occurred on the conductive layer after 4 repetitions.

Example 3 Mineral Spirit 150s
After dispersing the solution in L-lumil for 2 hours, add 0.2 parts of manganese nanthenate, disperse for another 10 minutes, and apply it on a 100 μm thick polyester film to a film thickness of 15 μm after drying. The coating was applied and dried as described above, and left at room temperature for 48 hours to form a conductive ridge layer. Next, a liquid formulation consisting of 30 parts of Phthalkid 375-100, 0.1 parts of manganese, and 50 parts of mineral spirits was dispersed using ultrasonic waves for 10 minutes, and the resulting film thickness after drying was 8 μm on the conductive layer. The dielectric layer was formed by coating and drying as described above and leaving it at room temperature for 48 hours. The surface hardness of the electrostatic recording material thus obtained was 6H in terms of pencil hardness.

No peeling was observed in the peel test.

Further, in the repeated test, the same good results as in Example 1 were obtained even after 10,000 repetitions.

Comparative Example 3 A dielectric layer with the same formulation as in Example 3 was applied onto the dielectric layer using the He IJ ester resin used in Example 2 as a non-inder, and the whole cloth was dried using a spray method so that the film thickness after drying was 8 μm. A dielectric layer was formed by leaving it at room temperature for 48 hours, and an electrostatic recording material was obtained.

This electrostatic recording material had the same surface hardness and peeling test results as Example 3, but in the repeated test, scratches occurred in the contact area after 3,000 repetitions, and -1ktl- Part of it had peeled off.

372-

Claims (1)

[Claims] l. Electrostatic recording in which a conductive layer mainly composed of conductive fine powder and resin is provided on a support, and a dielectric layer mainly composed of pigment and high-resistance resin is further provided thereon. An electrostatic recording material that uses the same resin or the same type of resin as the resin for the dielectric layer for at least a part of the resin for the conductive layer, and costs 7 yen H1k.