JPS63194268A - Electrostatic recording film - Google Patents

Abstract

PURPOSE:To balance fixability and blockability and to obtain an electrostatic recording film having high-quality image and good fixability by combining specific acrylic copolymers which are different in Tg as a high-polymer binder of a dielectric layer. CONSTITUTION:The dielectric layer consists of the high-polymer binder and particles. A mixture which contains at least one kid (A) selected from poly(meth) acrylate copolymers having >=65 deg.C Tg and at least one kind (B) selected from poly(meth)acrylate copolymers having <=25 deg.C Tg and is mixed with (A), (B) so as to have the T value obtd. by calculating Tg thereof by the equation in a 51-64 deg.C range is used as the high-polymer binder. In the equation, WA1, WA2,...WAn, WB1, WB2,...WBn denote the weight fractions of the poly(meth) acrylates (A), (B), and TgA1, TgA2,...TgAn, TgB1, TgB2,...TgBn denote Tg of the poly(meth)acrylates (A), (B) at the absolute temp. The electrostatic recording film having the stable high-quality image in high speed recording and good fixability is thus obtd.

Description

Detailed Description of the Invention [Industrial Field of Application] 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. It is related to 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.

"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.

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. (hereinafter abbreviated as the gap) to form an electrostatic latent image on the surface of the dielectric layer, and then this electrostatic latent image is developed with liquid toner and fixed as a visible image. be. In order to obtain a stable image of 1%, it is necessary to control the gap within an appropriate range from the Paschen curve, and for this purpose, for example, the pin electrode must be brought into contact with a dielectric layer that has been appropriately roughened by adding particles. The most commonly used method is to properly control the gap. On the other hand, since toner images on such electrostatic recording films are fixed without using heat or pressure and are simply left as they are, conventional electrostatic recording films have sufficient fixing properties compared to electrostatic recording paper. Therefore, the toner image tends to peel 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 during high-speed recording and has good fixing properties, which has been a major hindrance to its practical application.

Regarding the dielectric layer of electrostatic recording paper, the T(] (glass transition temperature) of the acrylic copolymer mixture should be within a specific range (
It is known that 9 is required to be between 10'C and 50'C (Japanese Patent Publication No. 19419/1989). Also, from the viewpoint of paper-like properties, the temperature must be 19h860°C or higher, and 20~40°C. A mixture of acrylic copolymers at ℃ is known (Japanese Patent Publication No. 57-35455).
However, there is no description at all about the preferable range of Tg of the mixture, or the relationship with fixing properties or blocking properties, and there is no description about 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 is difficult to satisfy both fixing properties and blocking properties with a single polymer binder. However, there is an area in which fixing and blocking properties can be balanced by combining polymer binders with different T (J), and this area is not necessarily the same as in the case of paper-based electrostatic recording paper. They found that this was a region unique to electrostatic recording films, and arrived at the present invention.

[Problems to be Solved by the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an electrostatic recording film that can stably produce high quality images at high speed recording and has good fixing properties.

[Means for Solving the Problems] In order to achieve the above object, the present invention has 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, the dielectric layer is composed of a polymer binder and particles, and as the polymer binder, (8) T( ] is higher than 65°C.
Contains at least one selected from meth)acrylic ester copolymers and at least one selected from poly(meth)acrylic ester copolymers with (B) To of 25°C or less, and has the following formula: [In the formula WAl, WA2,...W
An, WBl, WB2,...WBn are poly(meta)
The weight fractions of acrylic acid esters (A) and (B) are shown, and T(IA 1 , TgA2, -TgAn, T(IB
1. TgB 2-TgF3n is the Tg of poly(meth)acrylic acid ester (8), (B) expressed in absolute temperature.) The T value calculated by the method of 51-64℃
The electrostatic recording film is characterized in that it is an electrostatic recording film made of a mixture which is mixed so as to have the following range.

The dielectric layer of the present invention is composed of a polymer binder and particles, and the polymer binder includes (A) a poly(meth)acrylate copolymer having a Tg (glass transition temperature) of 65°C or higher; At least one selected species and (B) Tg of 25°C
Contains at least one selected from the following poly(meth)acrylic acid ester copolymers, and has the following formula [where WAl, WA2, ... WAn, WBL, WB
2,...WB71 indicates the weight fraction of poly(meth)acrylic acid esters (A) and (B), and T(IA 1,
T(IA2, ・T(JAn, TgB 1, T(I
B 2 = T (]Bx is the absolute temperature of 10 of poly(meth)acrylic acid ester (A), (B))] whose T value is 51 to 64°C. It is a mixture that has been mixed to achieve a range.

In addition, in the present invention, "poly(meth)acrylic acid...
" is an abbreviation for [polyacrylic acid...] and [polymethacrylic acid...].

Such poly(meth)acrylic acid ester copolymer (A)
, (B) refers to commonly known poly(meth)acrylic acid ester copolymers whose weight per gram is 65°C or higher [
As A), (8) has a Tg of 25°C or less,
Each can be used, but among them, monomer (
Groups I) to (III), i.e., (I>T as an individual polymer (J is 65°C or higher; n) T as an individual polymer (l is lower than 65°C;
higher than 25°C (III) T as a single polymer (when classified into those with l of 25°C or lower, (A) than a copolymer consisting of only a single group A copolymer selected from ■ and ■, ■ and ■, or ■, ■, and ■ with a T ( ) of 65°C or higher; (8) is a copolymer consisting of only one group (III); Rather than a combination, 1 g of a copolymer selected from ■ and ■, ■ and ■, or a copolymer selected from engineering, ■, and ■ is preferably 25°C or less. Examples of knobs are shown in Table 1.

The polymer binder of the present invention consists of the above (A) and (B), and it is necessary that its Tl1I is 51 to 64°C. For this purpose, the A/B weight ratio should be approximately 90/
It is preferable to select it in the range of 10 to 55/45. Furthermore, T
The value is preferably 51 to 64°C, more preferably 52 to 64°C.
Preferably, the temperature is 59°C.

If it is lower than this range, blocking properties will be poor, while if it is higher than this range, fixing properties 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 0.cm or more, more preferably 1Q10 Ω.cm or more. Examples of such inorganic particles include metal oxides such as silicon oxide, titanium oxide, alumina, lead oxide, and zirconium oxide; salts such as calcium carbonate, barium titanate, and barium sulfate; and examples of organic particles include styrene. - Suitably selected from divinylbenzene copolymer, melamine resin, epoxy resin, phenol resin, fluororesin, 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, which is not preferable.

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, it is preferable that the amount of the known polymer binder added to 100 parts by weight of the polymer binder of the present invention is 20 parts by weight or less, and furthermore, in the above formula, the amount of addition of the known polymer binder is 20 parts by weight or less. It is necessary that T calculated as one type of poly(meth)acrylic acid ester copolymer is 51 to 64°C.

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 nysdel, polyvinyl chloride,
Poly(meth)acrylic acid ester and the like are preferred.

Copolymers, blends, and crosslinked products of these may 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, polynisdel 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 prephthalic acid,
Isophthalic acid, naphthalene dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl dicarboxylic acid, anthracene dicarboxylic acid, α, β-bis(2-chlorophenoxy)ethane-4 , 4°-dicarboxylic acid, etc. Among these, terephthalic acid is particularly desirable.

Preferred examples of alkylene glycol include ethylene glycol, trimethylene glycol, detramethylene glycol, pentamethylene glycol, hexamethylene glycol, and hexylene glycol.

Of course, these polyesters may be homopolyesters or copolynisdels (copolymerized polyesters), and examples of copolymerizable components include diethylene glycol, propylene glycol, neopentyl glycol, polyalkylene glycol, and p-xylene. 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 p-oxyethoxybenzoic acid.

The thickness of the plastic film is 10 μm to 250 μm.
Preferably it is μm. More preferably 15 μm
It is desirable that the thickness is ~150 μm, and if it is thinner than this,
Mechanical strength as a film is insufficient, and if it is thicker than this, film transportability deteriorates, 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.

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

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

That is, in addition to the insulating PlusDeck film, if necessary, to the extent that the characteristics of the present invention are not impaired, in order to prevent the generation of static electricity on the surface of the plastic film opposite to the conductive layer, a film opposite to the conductive layer may be used. It is possible to use a plastic film with an antistatic layer or another conductive layer on the side surface, or with an antistatic agent added to provide electrical conductivity between the front and back sides of the plastic film.

Furthermore, matte or colored materials may be used if necessary. Alternatively, it may be a laminate of two or more types of plastic films.

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 preferable compositions include Ao, Cr
, Cd, Ti, re, Cu, In, Ni,
Pd.

Pt, Rh, Ag, Ru, W, Sn, Z
Metals such as r, Ir, stainless steel, brass, N1-c
alloy with r, indium oxide, tin oxide, zinc oxide,
Examples include, but are not limited to, metal oxides such as titanium oxide, vanadium oxide, 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. 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. 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 -5 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 Plus Deck film and a conductive layer is called a conductive film.

It should be noted that the preferable range of the surface electrical resistance of the conductive layer is known depending on the recording method, and generally in (a) surface control method it is 104
~108Ω/mouth, (B) 107~108 for surface control method
Ω/mouth, (c) 106 to 107 Ω/ in the same plane control method
It is said that the mouth is preferable.

In the present invention, so-called "fogging" may be applied as necessary.
A carbon electrode or the like may be provided at the end of the dielectric layer as is generally known as a countermeasure against "ghost" and the like.

[Effects of the Invention] The present invention provides an electrostatic recording film in which a plus-snack film, a conductive layer, and a dielectric are laminated in this order.Since a specific polymer binder is applied to the dielectric layer, the film is stable during high-speed recording. 1 q of electrostatic recording film with high quality images and good fixing properties was produced.

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 machines, facsimile receivers, and printers, and a record that retains a transferred electrostatic latent image in electrophotographic pro wrestling (TESI method) using the electrostatic latent image transfer method. It is useful as a recording film for displays using an electrostatic recording method.

[Method for measuring characteristics] (1) Surface electrical resistance Cut a conductive film to a width of 30 m, and assume two parallel lines perpendicular to the cutting line and with an interval of 30 InIn,
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 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 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 wet toner developer, and then dried to obtain 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 # of pixels, 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.

(b) Printing was performed at a pixel thickness of 16 dots/m, and the number of pixels per 100 m was measured. 60 pieces or less were judged as good, 61 to 200 pieces were judged as fair, and 201 pieces or more were judged as poor.

(c) The 21 degree solid black image area of the image was measured as a reflection density using a Sakura microdensitometer (Model PDM-5>), and the foul density was 0.
A value of 7 or more was considered good, and a value of less than 0.7 was considered poor.

(3) Fixability After measuring the image density (initial density) of the solid black image area, apply mending tape, then peel it off at 180°C.
The image density (residual density) of the peeled part is measured. A fixing rate of 60% or more was judged as good, and a fixing rate of less than 60% was judged as poor.

Residual bacteria W! Degree fixing rate = X100 (%) Initial density (4) Blocking property 50%
When peeled off after being left for 24 hours under a load of ~g/~, it is good: There is no adhesion at all, and there is no sound when peeled off. Slightly poor:
Items that do not stick but make a slight noise when peeled Defective: Items that make a loud noise or stick when peeled off [Example] The present invention will be explained below with reference to Examples, but the present invention is not limited by these. It's not a thing.

In addition, all the blended parts in the examples are hands and feet.

Examples 1 to 4 Pd was sputtered onto a biaxially oriented polyethylene terephthalate film (“Lumirror” manufactured by Toshi ■) with a diameter of 19×75 μm to obtain a conductive film with a surface electrical resistance of 1×10 Ω/hole. . A dielectric layer having the composition shown in Table 1 was coated on this conductive film (thickness after drying: 3 g).
/Tl1) Electrostatic recording film of the present invention (Examples 1 to 4)
I got it. These characteristic evaluations are summarized in Table 1. In addition,
The composition of the dielectric layer was polymer binder/particle=100/20. In addition, to prevent fogging, conductive tin oxide (1 Ω cm) was added at 0.5 parts per 100 parts of the polymer binder.
Part was added.

Comparative Examples 1 and 2 Comparative Examples 1 and 2 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 prepared in the same manner as in Example 2, except that the dielectric layer contained 10 parts and 50 parts of the particles.

These characteristic evaluations were performed in the same manner as in Example 2, including image quality, fixing properties,
All blocking properties were good.

In this example, even those with good fixing properties were able to be erased by rubbing strongly with a regular pencil rubber. In other words, if corrections are necessary, delete them,
I was also able to add notes with a pencil.

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 is composed of a polymer binder and particles, and as the polymer binder, (A) Tg at least one selected from poly(meth)acrylic acid ester copolymers having a temperature of 65° C. or higher;
(B) Contains at least one type selected from poly(meth)acrylic acid ester copolymers with a Tg of 25°C or less, and has the following formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula WA_1, WA_2, ...WA_n, WB_
1, WB_2,...WB_n represents the weight fraction of poly(meth)acrylic acid esters (A) and (B), and TgA
_1, TgA_2, ...TgA_n, TgB_1, T
gB_2...TgB_n is the Tg of poly(meth)acrylic acid esters (A) and (B) expressed in absolute temperature] The T value calculated by the method is in the range of 51 to 64 ° C. An electrostatic recording film characterized in that it is made using a mixture mixed as follows.