JPS61213851A - Electrostatic recording film - Google Patents

Abstract

PURPOSE:To obtain a clear image having no fog, little line aperture and few black spots by using a specified dielectric layer when an electrically conductive layer and a dielectric layer are successively formed on an insulating film to obtain an electrostatic recording film. CONSTITUTION:Palladium is sputtered on a biaxially stretched polyethylene terephthalate film of 75mum thickness to form an electrically conductive film having 7X10<6>OMEGA/square surface electric resistance. This electrically conductive film is coated with a dielectric layer consisting of acrylic resin, calcium carbonate and electrically conductive tin oxide to obtain an electrostatic recording film. This recording film gives an image having no fog, little line aperture, few black spots and superior image characteristics independently of relative humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrostatic recording medium that directly converts an electrical signal into an electrostatic latent image. In particular, it relates to an electrostatic recording medium with clear images and no fog.

[Prior art]

An electrostatic recording film is known in which an insulating film, a conductive layer, and a dielectric layer are laminated in this order.

In the electrostatic recording method, a recording voltage is applied to a multi-pin electrode head (hereinafter abbreviated as pin electrode), and an air discharge is generated in a micro gap (hereinafter abbreviated as gap) between the pin electrode and the dielectric layer of the electrostatic recording film. An electrostatic latent image is formed on the surface of the dielectric layer, and then this electrostatic latent image is developed with toner to form a visible image. In order to obtain clear images in this way, it is necessary to control the gap within an appropriate range from the Paschen curve, and for this purpose, the gap is adjusted by adding insulating particles and bringing the pin electrode into contact with a dielectric layer with appropriate irregularities. The most commonly used method is to appropriately control the It is known that in such electrostatic recording films, clear images cannot be obtained unless insulating particles are added to the dielectric layer, and on the other hand, "fogging" occurs if the conductive layer is incompletely grounded.

With conventional electrostatic recording paper, it is possible to ground from the paper side of the conductive paper, but with an electrostatic recording film using an insulating film, it is not possible to ground from the film side of the insulating film. For this reason, some products use a ground electrode by exposing a part of the conductive layer (the edge on the side) or by coating the exposed part with conductive paint such as carbon paint. Productivity is poor because it takes time to expose the conductive layer according to the width, and the manufacturing process increases to apply conductive paint. For this reason, a structure has been proposed in which conductive powder is dispersed in a dielectric layer, and the conductive powder is brought into contact with each other by applying a pressure higher than a certain level so as to have conductivity (Japanese Patent Publication No. 57-12
Publication No. 144).

Such an electrostatic recording film has a bottle electrode (the pressing force is 50~
After applying a charge at 100 g/word), before development, press with a conductive roll (pressing force 500 to 5000 g/all) to bring the conductive powder in the dielectric into contact and keep the conductive layer at the ground electrode. It is explained that fogging can be eliminated by this.

Although this kind of electrostatic recording film certainly eliminates fogging, in order to bring the conductive powder into contact through compression,
It is necessary to add a large amount of conductive powder, and in addition, a new defect occurs in which pixels drop out in a line in the direction parallel to the recording electrode (hereinafter referred to as "line dropout"), and the pixel thickens due to abnormal discharge ( There are problems such as an increase in the number of people (hereinafter abbreviated as "Gomajio").

[Problem that the invention seeks to solve]

The object of the present invention is to eliminate the above-mentioned drawbacks and prevent fogging.

It is an object of the present invention to provide an electrostatic recording film that has few line dropouts and black spots and can provide clear images.

[Means for solving problems]

In order to achieve the above object, the present invention consists of a secondary structure. i.e. insulating film, conductive layer.

In an electrostatic recording film in which dielectric layers are laminated in this order, the dielectric layer comprises at least a polymeric binder, insulating particles, and conductive powder, and the weight ratio of the polymeric binder to the conductive powder is is 10070.1 to 100/10.

The dielectric layer of the present invention is composed of a polymer binder, insulating particles, and conductive powder, and the weight ratio of the polymer binder to the conductive powder is 10010.1 to 100/10.

The polymeric binder used in the present invention is made of a thermoplastic resin or a curable resin, and various resins commonly used in the dielectric layer of electrostatic recording films can be used. Examples of thermoplastic resins include polyester, polyesteramide, polyvinyl acetal, polyvinyl chloride, poly(meth)acrylate, polyamide, polyurethane,
Polycarbonate, polystyrene, polymethylpentene.

Alkyd resin, polyamideimide, silicone resin.

Examples include fluororesins, copolymers and blends thereof. Curable resins that harden with heat, light, oxygen, etc. include (1) phenol resins, melamine resins, epoxy resins, crosslinked organosilicon compounds, (2) poly(meth)acrylic acid ester copolymers containing reactive monomers, etc. Examples include those that are crosslinked by adding a crosslinking agent. These polymer binders preferably have a volume resistivity of 10 Ω1 or more. If it is smaller than this, the print density will be low, which is not preferable.

The conductive powder preferably has a volume resistivity of 10 to 10 Ω·1, and commonly known conductive powders are used. Such preferred compositions include *Ale4e Cr, Cd, Ti, 11. Cu, In, N
i, Pd, Pt, Rh, Ag.

Metals such as Ru, W, Sn, Zr, Ir, stainless steel, brass, alloys such as Ni-Cr, indium oxide, tin oxide, zinc oxide, titanium oxide, vanadium oxide.

Examples include, but are not limited to, metal oxides such as ruthenium oxide and tantalum oxide, and metal compounds such as copper iodide. These may be used alone or in combination in a combination or mixture of two or more. These conductive powders preferably have a small average particle size, 0.01 to 10
Pm is preferred.

More preferably, the thickness is 0.1 to 5 μm. If it is smaller than this, the dispersibility will be poor; on the other hand, if it is thicker than this, 9
This is undesirable because uniformity of image quality cannot be obtained.

is preferable. If it is larger than this, the effect on eliminating fogging will be small and undesirable.

The weight ratio of polymer binder and conductive powder is -0070.1~
It is necessary that the ratio is 1 to 100/10. More preferably, it is 10070.3 to 10015. If the amount is less than this, the effect of eliminating fogging will be less.
If it is more than this, there will be many broken lines and irregularities, which is not preferable.

As an insulating particle, 9 volume resistivity is 1oΩ・on the side line,
More preferably, commonly known inorganic and/or organic particles having a resistance of 10 Ω or more are used. Examples of such inorganic particles include metal oxides such as silicon oxide, titanium oxide, alumina, lead oxide, and zirconium oxide;
Examples of salts such as calcium carbonate, barium titanate, and barium sulfate, and organic particles include styrene-divinylbenzene copolymer, melamine resin, and epoxy resin.

It is appropriately selected from phenol resins, fluororesins, etc. These insulating particles may be used alone or in combination of two or more. The average particle size of the insulating particles is generally preferably selected from the range of 0.1 to 20/Am in view of discharge stability. The weight ratio of polymer binder and insulating particles is 10
It is preferable that it is 070.5-100/150. If it is less than this, the stability of the discharge will be poor, and if it is more than this, the film strength of the dielectric layer will be weakened, which is not preferable.

The thickness of the dielectric layer is preferably 1-20 pm.

If it is thinner than this, the surface potential will change, and if it is thicker than this, the resolution will deteriorate, which is not preferable.

The dielectric layer may be a single layer or a plurality of layers,
Further, an intermediate layer such as an adhesive layer may be provided between the conductive layer and the dielectric layer.

The dielectric layer of the present invention may contain plasticizers, adhesion promoters, stabilizers, antioxidants, ultraviolet absorbers, and lubricants as necessary to the extent that they do not impair the properties of the electrostatic recording film that is the object of the present invention. etc. may be added.

In the present invention, an insulating protective layer containing no conductive powder may be provided on the dielectric layer. The thinner the protective layer is, the better, and it is desirable that the thickness of the protective layer is 5 μm or less, more preferably 1 μm or less.

Generally known methods are effectively used to add the dielectric layer. For example, brush painting, dip painting, knife painting, roll painting, spray painting, flow painting.

Appropriately selected from rotary coating (spinner, whaler, etc.), etc.

The insulating film used in the present invention is:

It is a film made of an insulating thermoplastic resin or thermosetting resin having a commonly known volume resistivity of 10 Ω·(2) or more. The resins used for this film include polyester, polyolefin, polyamide, polyester amide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, polyP-fluorinated sulfide, polyether ester, polyvinyl chloride, and poly(meth)acrylate. IJ/l/acid ester, etc. are preferred.

Furthermore, copolymers, blends, and crosslinked products of these can also be used. Further, it is preferable to stretch these resins because mechanical strength, one-dimensional stability, thermal properties, optical properties, etc. are improved. Among these, polyester is preferably used. Here, the polyester is a polyester containing an aromatic dicarboxylic acid as a main acid component and an alkylene glycol as a main glycol component.

Specific examples of aromatic dicarboxylic acids include terephthalic acid,
Isophthalic acid, naphthalene dicarboxylic acid.

Diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid.

Diphenylsulfone dicarboxylic acid, diphenylketone dicarboxylic acid, anthracene dicarboxylic acid.

α,β-bis(2-chlorophenoxy)ethane-4,4
/-dicarboxylic acid and the like. Among these, terephthalic acid is particularly desirable.

Specific examples of alkylene glycol include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and hexylene glycol.

Of course, these polyesters may be homopolytennis gal or copolyester (copolymerized polyester), and copolymerizable components include, for example, diethylene glycol, propylene glycol, neopentyl glycol, and polyalkylene glycol. , P
- Diol components such as xylylene glycol, 1,4-cyclohexane dimetatool, and 5-sodium sulforesorcin.

Adipic acid, sebacic acid, phthalic acid, inphthalic acid, 2
．． Dicarboxylic acid components such as 6-naphthalene-dicarboxylic acid and 5-natriramsulfoisophthalic acid.

Examples include polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as P-oxyethoxybenzoic acid.

The thickness of the plastic film is 10/A m・
It is preferable that it is 250 micrometers. More preferably, it is 15 pm to 150 μm. If it is thinner than this, the film will not have sufficient mechanical strength, and if it is thicker than this, the membrane permeability will be poor, which is not preferable.

These plastic films may be subjected to known surface treatments, such as corona discharge treatment, plasma discharge treatment, anchor coating, etc., to improve adhesion, if necessary.

Furthermore, in order to prevent the occurrence of scratches during running, the insulating film has a static friction coefficient of 2.0 or less, more preferably 1.0.
It is preferable that it is below.

As the conductive layer of the present invention, a commonly known conductive layer is used. The surface electrical resistance is preferably 10 to 10 Ω/hole. Such conductive layers include (1) those made of electronically conductive metals or metal oxides, (2) those coated with ionically conductive polymer electrolytes, and (3) conductive powders and polymer binders. or those coated with a layer consisting of a polymer electrolyte.

In this case, the conductive powder used in the dielectric layer can be used, and the polymer electrolyte includes, but is not limited to, quaternary ammonium salts, sulfonates, and polyalcohols.

These may be used alone or in combination of two or more. Such a conductive layer may be formed by plating, vacuum deposition, chemical vapor deposition, sputtering, coating, or the like. Among these, an island-shaped discontinuous metal film made of a material mainly consisting of at least one metal selected from the group consisting of Rh, Pd, Ir, Pt, and Ru has the following characteristics: uniformity of surface electrical resistance, humidity It is particularly preferred from the viewpoint of stability against. Note that the island-shaped discontinuous metal film is one in which metal particles are scattered on an insulating film, and the average size thereof is particularly preferably in the range of 10-' to 10 square microns. The density of the island-shaped discontinuous metal film is preferably 15 to 50% in terms of area fraction.

A laminate of the above insulating film and a conductive layer is called a conductive film.

〔Effect of the invention〕

By applying a specific dielectric layer to an electrostatic recording film in which an insulating film, a conductive layer, and a dielectric layer are laminated in this order, the present invention achieves clear image quality with no fogging in one image, fewer line omissions and black spots, and a clear image quality. This is what I was able to obtain.

As described above, the electrostatic recording film of the present invention has excellent properties, so it can be used not only as an electrostatic recording film for hard copies, for electrostatic recording printers/plotters, and for facsimiles, but also for repeated use. The electrostatic recording film for the master film used is transfer master for copiers, facsimile receivers, and printers, and electrophotographic process using electrostatic latent image transfer method (TESI).
It is useful as a recording medium that retains a transferred electrostatic latent image using the electrostatic recording method (method), and as a recording film for displays using an electrostatic recording method.

[Method of measuring characteristics]

(1) Surface electrical resistance A conductive film is cut to a width of 30nnn, and two parallel lines are assumed to be perpendicular to the cutting line and spaced apart by 30mm,
Conductive carbon paint is applied to the right and left sides, excluding the area between the two lines, and used as electrodes. The electrical resistance between the electrodes was measured at 20° C. and 65% RH using a Keithley electrometer (type 610OL). The unit is Ω/mouth. The surface electrical resistance of the electrostatic recording film was also measured in accordance with this method.

(2) Image Quality An electrostatic latent image was formed on the surface of the electrostatic recording film using a multi-pin electrode head, and then the electrostatic latent image was visualized using a liquid toner developer and dried to obtain a hard copy image. Note that no rolls or the like were used between the head and the developing machine to contact the surface of the dielectric layer and apply pressing force. The tests were conducted under conditions of relative humidity (hereinafter referred to as RH) of 20%, 60%, and 80%, respectively.

(a) The reflection density of the blank area of the fogged image recording was measured using a Sakura microdensitometer (model PDM-5), and those with a reflection density of 0.3 or more were judged as defective.

(b) 10 (same direction as the head) x 10 dots with a line break of 125 μm
0 (perpendicular to the head)).

The number of line breaks was measured. An average value of n=5 of 5 or less was considered good, 6 to 15 was considered fair, and 16 or more was bad.

(c) Sesame Geo 125 μm dots were printed at a rate of 8/1111 dots.

The number of sesame seeds per 100 m+ was measured. 40 or less pieces were judged as good, 41 to 150 pieces were judged as fair, and 151 pieces or more were judged as poor.

〔Example〕

The present invention will be explained below with reference to Examples. The present invention is not limited to these. In addition, all the blended parts in the examples are parts by weight.

Examples 1 to 5 Pd was sputtered onto a 75 μm thick biaxially stretched polyethylene terephthalate film (“Lumirror” manufactured by Toshi ■) to obtain a conductive film having a single surface electrical resistance of 7×10 Ω/hole. A dielectric layer having the composition shown in Table 1 was coated on this conductive film (thickness after drying was 3 g/
m”) Electrostatic recording film of the present invention (Examples 1 to 5)
I got it. These properties are summarized in Table 1.

Comparative Examples 1 to 6 Comparative Examples 1 to 3 were obtained in the same manner as in Example 1, except that the dielectric layer composition was as shown in Table 1.

From Table 1, the electrostatic recording films of Examples 1 to 5) of the present invention have no fogging regardless of relative humidity compared to Comparative Examples 1 to B.
In addition, it is clear that it exhibits excellent image characteristics with fewer line omissions and irregularities. In addition, Examples 1 to 5 had good transparency (Nippon Seimitsu Kogaku 5PF (ERE METHOD)).
The total light transmittance at 550 Ωm was measured using METER (TYPE SEP-H-8). More than 75% of the cases were dogs. ).

It could be used as a transparent electrostatic recording film for electrostatic blocks.

Example 6 PT was sputtered onto a 100 μm thick biaxially stretched polyethylene terephthalate film (“Lumirror” manufactured by Toshi ■) to obtain a conductive film having a surface electrical resistance of 1×10 Ω/hole. A self-crosslinking acrylic emulsion was applied onto this conductive film to a thickness of 0.5 μm after drying.
After forming an adhesive layer by applying the coating to a thickness of m, polyester resin (“Vylon” manufactured by Toyobo ■)/alumina/conductive zinc oxide (100Ω・c−) = 100/20
/ 1 (solvent: tetrahydrofuran) (total weight of adhesive layer and dielectric layer after drying is 8 g/m").

An electrostatic recording film (Example 6) of the present invention was obtained.

The alumina used had a Mohs hardness of 9.

These characteristics are summarized in Table 1. From Table 1.

It is clear that the electrostatic recording film of the present invention (Example 6) exhibits excellent image characteristics, with no fogging and fewer lines and spots. Also.

The developed toner image was not fixed as it was, but was transferred to plain paper and then fixed to obtain a hard copy.Meanwhile, the electrostatic recording film was charged and cleaned of residual toner and used repeatedly. In this case, the hard copy after 10,000 repetitions is 1
Similar to the second one.

It exhibited excellent image characteristics with no fogging, and few line omissions and black spots. From this, it is clear that the electrostatic recording film of the present invention is also excellent as a master film.

Examples 7 and 8 A dielectric layer having the composition shown in Table 2 was coated on the conductive film of Example 1 to prepare an electrostatic recording film of the present invention (Example 7).
, 8) were obtained. These characteristics are summarized in Table 2. All showed excellent image characteristics.

Claims (1)

[Claims] (1) In an electrostatic recording film in which an insulating film, a conductive layer, and a dielectric layer are laminated in this order, the dielectric layer is composed of at least a polymer binder, insulating particles, and conductive powder, and The weight ratio of binder and conductive powder is 100/
An electrostatic recording film characterized in that the ratio is 0.1 to 100/10.