JPS63136049A - Electrostatic recording film - Google Patents

Abstract

PURPOSE:To produce electrostatic recording film capable of providing high quality picture image stably at high recording speed by incorporating a specified amt. of specified polyester copolymer and poly(meth)acrylic ester copolymer, as high molecular binder in a dielectric layer. CONSTITUTION:(A) A least one kind selected from polyester copolymers having >=40 deg.C Tg, and (B) at least one kind selected from poly(meth)acrylic ester copolymers having <=20 deg.C Tg are contained as high molecular binder in a dielectric layer, and the weight ratio of A to B is regulated to 98/2-50/50. In this case, the polyester copolymer having >=40 deg.C Tg is satd. polyester resin obtd. by copolymerizing a satd. polyvalent carboxylic acid with a satd. polyhydric alcohol. Preferred satd. polyvalent carboxylic acid is terephthalic acid, isophthalic acid, phthalic acid, etc. Preferred monomer for the poly(meth)acrylic ester copolymer is methyl acrylate, ethyl acrylate, n-propyl acrylate, etc. By this constitution, electrostatic recording film capable of providing stably high quality picture image at high recording speed is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrostatic recording film, and in particular to an electrostatic recording film that directly converts an electrical signal into an electrostatic latent image and then develops it with toner to create a visible image. Regarding recording film. More specifically, the present invention relates to an electrostatic recording film used in electrostatic recording printers and plotters for CAD (interactive design) and the like.

[Conventional technology]

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

The electrostatic recording method, which is generally used in electrostatic plotters for CAD, applies a recording voltage to a multi-pin electrode head (hereinafter abbreviated as pin electrode), and creates micro-gaps 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 by causing an air discharge in the gap (hereinafter abbreviated as gap),
This electrostatic latent image is then developed with liquid toner and fixed as a visible image. In order to obtain a stable image 1q, it is necessary to control the gap within an appropriate range from the Paschen curve, and for this purpose, for example, by adding particles and making the pin electrode contact a dielectric layer with appropriate irregularities. The most commonly used method is to properly control the gap. On the other hand, toner images on such electrostatic recording films are fixed without using heat or pressure, and simply by leaving them as they are, so conventional electrostatic recording films have sufficient fixing properties compared to electrostatic recording paper. Therefore, the toner image often peels off from the dielectric layer when it is touched or rubbed by hand.

Electrostatic recording film has features such as recording stability, transparency, dimensional stability, strength, dust resistance, and storage stability compared to conventional electrostatic recording paper, so its development is desired. It has been difficult to obtain a method that stably provides high-quality images with high-speed recording and has good fixing properties, which has been a major hindrance to its practical application.

It is known that the dielectric layer of electrostatic recording paper requires an acrylic copolymer mixture to have a TO (glass transition temperature) within a specific range from the viewpoint of the balance between curl resistance and blocking resistance. (Tokuko Showa 57-1)
No. 9419 does not describe the relationship with fixing properties, nor does it describe the case of an electrostatic recording film.

The present inventors have conducted extensive studies on improving the fixing properties of toner images formed with liquid toner on electrostatic recording films, and have found that it has not been possible to satisfy both fixing properties and blocking properties with a single polymeric binder. Although it is difficult, there is an area where fixing and blocking properties can be balanced by combining polymer binders with different specific Tg, and this area does not necessarily match the case of paper-based electrostatic recording paper. However, they discovered that this is a region unique to electrostatic recording films, and arrived at the present invention.

[Problem that the invention seeks to solve]

An object of the present invention is to eliminate the above-mentioned drawbacks and provide an electrostatic recording film that can stably obtain high-quality images during high-speed recording and has good fixing properties.

[Means for solving problems]

In order to achieve the above object, the present invention consists of the following configuration. That is, in an electrostatic recording film in which a plastic film, a conductive layer, and a dielectric layer are laminated in this order,
In the dielectric layer, as a polymer binder, (A) at least one selected from polynisder copolymers having a Tg of 40°C or higher, and (B) a poly(meth)acrylic acid ester having a TCI of 20°C or lower. The present invention is characterized by an electrostatic recording film containing at least one selected from polymers and having a weight ratio of A/B of 98/2 to 50,150.

The polymer binder used in the dielectric layer of the present invention is (A)T
At least one type selected from polyester copolymers having g (glass transition temperature) of 40°C or higher, and (B) TCI of 2
and at least one selected from poly(meth)acrylic acid ester copolymers at a temperature of 0°C or less, and the weight ratio is A.
/B=98/2 to 50150.

Among the saturated polyester resins commonly known as polyester copolymers with Tg of 40°C or higher, Tg
A material with a temperature of 40°C or higher is used.

Such saturated polyester resins are obtained by copolymerizing saturated polycarboxylic acids and saturated polyhydric alcohols, and the saturated polycarboxylic acids include terephthalic acid, isophthalic acid,
Saturated polyhydric alcohols include phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, 1,4 cyclohexanedicarboxylic acid, trimellitic anhydride, etc. Glycol, 1,4 butanediol, 1,5bentanediol, 1.6 hexanediol,
diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene glycol,
Propylene glycol, neopentyl glycol, 1,
4-cyclohexane dimetatool, pentaerythritol, trimethylolpropane and the like are preferably used.

As the poly(meth)acrylic ester copolymer having a TCI of 20° C. or less, among commonly known poly(meth)acrylic ester copolymers, those having a TQ of 20° C. or less are used. Examples of (meth)acrylic acid esters include (meth)acrylic esters whose homopolymer Tg is 20°C or less, such as mediyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and lactic acid ester. Hexyl, 2-ethylhexyl acrylate, ln-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, and similar copolymers, and in addition to these, homopolymers with a Tq higher than 20°C, such as methyl methacrylate, Those copolymerized with ethyl methacrylate, n-propyl methacrylate, etc. and having a TCI of 20° C. or less as a copolymer are preferably used.

The weight ratio of (^) and (B) is A/B = 98/2 ~ 501
50, and is preferably selected within this range. Roughly preferably A/B=9515-60/4
It is desirable that it be 0. If the weight ratio is larger than this, the fixing property will be poor, and if it is smaller than this, the blocking property will be poor, which is not preferable.

Particles are used in the dielectric layer of the present invention to form gaps. As the particles, commonly known inorganic particles or organic particles are used. Such particles have a volume resistivity of 108
It is preferably at least Ω·cm, more preferably at least 1010 Ω·cm. Examples of such inorganic particles include metal oxides such as silicon oxide, titanium oxide, alumina, lead oxide, and zirconium oxide, calcium carbonate,
Examples of salts such as barium titanate and barium sulfate, and organic particles include styrene-divinylbenzene copolymer, melamine resin, epoxy resin, phenol resin,
The material is appropriately selected from fluororesins, etc.

These particles may be used alone or in combination of two or more. The average particle size of the above particles is generally 0.1 from the viewpoint of discharge stability.
It is preferable to select the thickness appropriately within the range of 15 μm.

In the present invention, the weight ratio of the polymer binder and particles forming the dielectric layer is preferably selected within the range of 10010.5 to 100/150. If the weight ratio is lower than this,
The stability of discharge is poor, and if it exceeds this range, the film strength of the dielectric layer will weaken, which is not preferable.

The thickness of the dielectric layer is preferably 1 to 20 μm; if it is thinner than this, the surface potential will be low, and if it is thicker than this, the resolution will be poor.

The dielectric layer may be a single layer or a plurality of layers.

For example, a layer made of the polymer binder of the present invention may be laminated on a dielectric layer made of a commonly known polymer binder and particles. In this case, the layer made of the polymer binder of the present invention may be a layer that does not contain particles, and preferably has a thickness of 0.1 to 3 μm. If it is thinner than this, the fixing property cannot be obtained, and if it is thicker than this, the blocking property may deteriorate, so these are not preferable. Further, an intermediate layer such as an adhesive may be provided between the conductive layer and the dielectric layer.

The dielectric layer of the present invention may contain known polymer binders, plasticizers, adhesion promoters, stabilizers, oxidation agents, etc. as necessary within the range that does not impair the properties of the electrostatic recording film that is the object of the present invention. Inhibitors, ultraviolet absorbers, lubricants, etc. may be added, and
Conductive powder or the like may be added to prevent fogging.

in this case. The amount of the known polymer binder added to 100 parts by weight of the polymer binder of the present invention is preferably 20 parts by weight or less.

Generally known methods are effectively used to add the dielectric layer. For example, the coating is appropriately selected from brush coating, dip coating, knife coating, roll coating, spray coating, flow coating, rotary coating (spinner, whaler, etc.), and the like.

The plastic film used in the present invention is a film made of a commonly known thermoplastic resin or thermosetting resin. The resin for this film includes polyester, polyolefin, polyamide, polyester amide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-p-phenylene sulfide, polyether ester, polyvinyl chloride,
Poly(meth)acrylic acid ester and the like are preferred.

Furthermore, copolymers, blends, and loosely crosslinked products of these can also be used. Further, it is preferable that these resins be stretched, since mechanical strength, 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 diphenylsulfone dicarboxylic acid, diphenyl ketone 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 homopolynisder or copolyester (copolymerized polyester), and copolymerizable components include, for example, diethylene glycol, propylene glycol, neopendel glycol, polyalkylene glycol, and Kano xylylene. Diol components such as glycol, 1,4-cyclohexane dimetatool, 5-sodium sulforesorcin, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-
Examples include dicarboxylic acid components such as naphthalene dicarboxylic acid and 5-sodium sulfoisophthalic acid, polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and oxycarboxylic acid components such as oxyethoxybenzoic acid.

The thickness of the plastic film is 10 μm to 250 μm.
Preferably it is μm. Roughness preferably 15μm
It is desirable that it is ~150 μm;
The film does not have sufficient mechanical strength, and if it is thicker than this, the reverse membrane properties will deteriorate, 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, the plastic film preferably has a static friction coefficient of 2.0 or less, more preferably 1.0 or less, in order to prevent scratches during running.

In the present invention, the volume resistivity of the plastic film is not particularly limited, and is appropriately selected depending on the electrostatic recording method.

As the conductive layer of the present invention, a commonly known conductive layer is used. The surface electrical resistance is preferably 10 4 to 10 9 Ω/mouth. 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 powder and polymer binder. or those coated with a layer consisting of a polymer electrolyte.

In this case, commonly known electron conductive metals, metal compounds, ion conductive polymer electrolytes, and conductive powders are used. Such preferred compositions include AQ, Cr,
Cd, Ti, Fe, Cu, In, old, Pd
.

Pt, Rh, Ag, Ru, w, Sn, Zr
, metals such as Ir, stainless steel, brass, alloys with Ni-Cr, metal oxides such as indium oxide, tin oxide, zinc oxide, titanium oxide, vanadium oxide, ruthenium oxide, tantalum oxide, copper iodide, etc. Examples include, but are not limited to, metal compounds. These may be used alone or in combination in a combination or mixture of two or more. Examples of the polymer electrolyte include, but are not limited to, quaternary ammonium salts, sulfonate salts, 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 is used to improve uniformity of surface electrical resistance and humidity. It is particularly preferred from the viewpoint of stability against. Incidentally, the island-shaped discontinuous metal film is one in which metal particles are scattered on a plastic film, and the average size thereof is particularly preferably in the range of 10 to 10 -2 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 plastic film and a conductive layer is called a conductive film.

The preferable range of the surface electrical resistance of the conductive layer is known depending on the recording method, and generally in (a) it is 104 to 108 Ω.
/mouth, (b) 107~108Ω/mouth, (c) 1
It is said that 06 to 107 Ω/mouth is preferable.

〔Effect of the invention〕

The present invention provides an electrostatic recording film in which a plastic film, a conductive layer, and a dielectric layer are laminated in this order, in which a specific polymeric binder is applied to the dielectric layer, so that high-quality images can be stably produced during high-speed recording. Thus, an electrostatic recording film with good fixing properties could be obtained.

The effects of the present invention are particularly remarkable when the conductive layer is a thin film of an electron-conductive metal, metal oxide, or metal compound formed by vacuum deposition, chemical vapor deposition, sputtering, or the like.

As described above, since the electrostatic recording film of the present invention has excellent properties, 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 a transfer master for copying services, facsimile receivers, and printers, and a recording medium that retains a transferred electrostatic latent image in an electrophotographic process using an electrostatic latent image transfer method (TESI method). Furthermore, it is useful as a recording film for displays using an electrostatic recording method.

[Method of measuring characteristics]

(1) Cut the surface electrical resistance conductive film to a width of 30 mm, and assume two parallel lines perpendicular to the cut line and 30 mm apart. A conductive carbon paint is applied to each, and this is used as an electrode. The electrical resistance between the electrodes was measured at 20°C and 65% RH using a Keithley electrometer (type 6100L), and the unit is Ω/mm. The surface electrical resistance of the electrostatic recording film is also measured in accordance with this. It was measured.

(2) Image Quality An electrostatic latent image is formed on the surface of the electrostatic recording film using a multi-pin electrode head, and then the electrostatic latent image is visualized using a liquid toner developer, and then dried to form a hard copy image ( Three recording methods were selected as appropriate: (a) single-sided control, (b) double-sided control, and (c) same-sided control.

(a) Printing was performed at 16 dots per stroke, and the number of pixels per 100 m was measured. 80 or less pieces were judged as good, 81 to 250 pieces were judged as fair, and 251 pieces or more were judged as poor.

(Example) Printing was performed with a pixel thickness of 16 dots/mm, and the number of pieces per pixel per 100ITIIr was measured. 60 or less were considered good, and 61
~200 pieces were rated as somewhat good, and 201 or more pieces were rated as poor.

(c) Image density The solid black image area was measured as a reflection density using a Sakura microdensitometer (model PDM-5>), and the anti-gA′f:i
Those with a degree of 0.7 or more were considered good, and those with a degree of less than 0.7 were judged as poor.

(3) Fixability After measuring the image density (initial density) of the solid black image area, apply mending tape, then peel off 180',
The image density (residual density) of the peeled part is measured.

Residual density fixation rate = X100 (%) Initial density (4) Blocking property 50
When peeled off after applying a load of q/cm2 and leaving it for 24 hours, Good: No adhesion at all and no sound when peeled. Slightly poor. 2. No adhesion but a slight noise when peeled. Poor: When peeled off. , something that makes a loud noise or is sticky [Example] The present invention will be described below with reference to Examples, but the present invention is not limited by these.

In addition, all the blended parts in the examples are parts by weight.

Examples 1 to 4 Pd was sputtered onto a biaxially stretched polyethylene terephthalate film ("Lumirror" manufactured by Toshishiku Co., Ltd.) having a thickness of 75 μm to obtain a conductive film having a surface electrical resistance of 1×10 7 Ω/hole. The first layer is placed on top of this conductive film.
Apply a dielectric layer with the composition shown in the table (thickness after drying: 3
g/Tr12) Electrostatic recording film of the present invention (Example 1 to
4) was obtained. These characteristic evaluations are summarized in Table 1. The composition of the dielectric layer is polymer binder/particles = 100/2.
It was set to 0. In addition, to prevent fogging, conductive tin oxide (1Ωcm) was added at 0% to 100 parts of the polymer binder.
．． 5 parts were added.

Comparative Examples 1 to 3 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.

Examples 1 to 1 showing electrostatic recording films of the present invention from Table 1
It is clear that No. 4 has good image quality and excellent fixing and blocking properties.

Example 5.6 Example 5.6 was obtained in the same manner as in Example 1, except that the surface electrical resistance of the conductive film and the dielectric layer composition were as shown in Table 1. These characteristic evaluations are as shown in Table 1, and all were good.

Example 7.8 Example 7.8 was obtained in the same manner as in Example 2, except that the amount of particles in the dielectric layer was 10 parts and 50 parts.

Similar to Example 1, these characteristics were evaluated for image quality, fixing properties,
All blocking properties were good.

Claims (1)

[Claims] (1) In an electrostatic recording film in which a plastic film, a conductive layer, and a dielectric layer are laminated in this order, the dielectric layer contains (A) a polyester copolymer with a Tg of 40°C or higher as a polymer binder. at least one species and (
B) Contains at least one type selected from poly(meth)acrylic acid ester copolymers having a Tg of 20°C or less, and the weight ratio thereof is A/B = 98/2 to 50/50. electrostatic recording film.