JPH05249704A - Electrostatic recording body - Google Patents

Abstract

PURPOSE:To prevent contamination due to the triboelectrification generated in a color electrostatic plotter, etc., by incorporating a quaternary ammonium salt compd. with the saturation coefft. of water absorption below a specified value in a specified environment into a dielectric layer. CONSTITUTION:A quaternary ammonium salt compd. with the saturation coefft. of water absorption controlled to <=1.0% at 30 deg.C and 80% RH is selectively used in a dielectric layer. The saturation coefft. of water absorption is obtained by allowing the compd. to stand for 24hr in a humidity-conditioned atmosphere and measuring an increase in weight. The compd. is added to make the triboelectrification characteristic positive polarity, and the amt. is generally controlled to about 0.1-10%, preferably about 0.5-5%, of the solid in the dielectric layer. When the amt. is too small, a desired effect is not produced, and, when the amt. is too large, the compd. is crystallized and the picture density is decreased. Clay, halloysite, etc., are exemplified as the pigment constituting the dielectric layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording material suitable for an electrostatic recording system such as a high density electrostatic plotter of 400 dots / inch, an electrostatic facsimile, an electrostatic printer, etc. The present invention relates to an electrostatic recording body suitable for electronic recording.

[0002]

2. Description of the Related Art In recent years, with the progress of communication means, there is a demand for an output capable of high density recording. Since the electrostatic recording method is excellent in image quality and recording speed, it is widely used in various fields such as a terminal printer of a computer, a facsimile, an output device of a CAD system, or a design design using a computer graphic. ..

In addition, 400 dots / high density recording is possible.
The inch color electrostatic plotter was developed, and it has become possible to record clear color images on a large screen. The recording method of a normal color electrostatic plotter has four multi-needle electrode heads (cyan, magenta, yellow, black) and a single-pass method with a developing device for each, one multi-needle electrode and each of the above colors. There is a multi-pass system equipped with four developing devices corresponding to. In the multi-pass method, generally, a multi-needle electrode head forms a first-color negative electrostatic latent image on a recording medium, develops the electrostatic latent image with a positive polarity developer, and then once the recording medium is recovered. Back to the position of, then the electrostatic latent image of the second color is formed on the same surface, and the same developing operation is performed for the third color and the fourth color.
A color image is formed repeatedly with the colors.

By the way, in order to obtain a clear image by the electrostatic recording method, it is necessary to control the size of the void between the multi-needle electrode and the dielectric layer within an optimum range estimated from the Paschen's curve. .. Therefore, a pigment is generally mixed in the dielectric layer of the electrostatic recording medium as a spacer means for controlling the discharge interval with the multi-needle electrode. In the convex portion formed of the pigment in the layer, it seems that the pigment surface is covered with the resin thinly.

[0005]

When this electrostatic recording material is recorded by a color electrostatic plotter, the convex portions are rubbed with the recording needle electrode block while the recording material travels in the plotter many times, so that the electrostatic charging is prevented. Wake up. Further, when it comes into contact with a developing device or a travel auxiliary roller, frictional charging or peeling charging occurs.
The electrostatic charge generated on the surface of the electrostatic recording material is not easily attenuated because the dielectric layer is insulative. In particular, when the electrostatic charge generated by frictional charging has a negative polarity, the developer having a positive polarity is used. Is developed, and a spot-like or irregular stain pattern is generated on the recording material, and the image quality is significantly deteriorated.

Therefore, it is possible to impart conductivity to the surface of the dielectric layer so as to attenuate the triboelectric charge on the surface of the dielectric layer. However, if the electroconductivity is imparted to such a degree that the triboelectric charge is easily attenuated, recording is performed. Therefore, the electrostatic latent image itself formed on the surface of the dielectric layer is also attenuated, and as a result, it becomes difficult to obtain a high-density recorded image.

As a result of earnest studies on a method for solving these contradictions, the present inventor paid attention to the polarity of the electrostatic charge generated by friction, and the electrostatic charge generated by triboelectrification so as not to be developed with a positive polarity developer. We have found a method of controlling the polarity of charge to be positive. As a result of further intensive research, when a specific quaternary ammonium salt compound is contained in the dielectric layer constituting the electrostatic recording medium, the stain caused by the triboelectric charging generated in the color electrostatic plotter is extremely effective. They found that a clear recorded image can be obtained by solving the problems, and completed the present invention.

[0008]

The present invention relates to an electrostatic recording body comprising a conductive support on which a dielectric layer containing an insulating resin and a pigment as main components is formed. 30 ° C
An electrostatic recording material comprising a quaternary ammonium salt compound having a saturated water absorption rate of 1.0% or less under an 80% RH environment.

[0009]

In the electrostatic recording material of the present invention, examples of the insulating resin forming the dielectric layer include methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, isobutyl methacrylate. Polymers of acrylic acid esters and methacrylic acid esters such as, and copolymers of these with a small amount of functional groups such as acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid, acrylonitrile, and methacrylonitrile, acetic acid. Vinyl, ethylene-vinyl acetate copolymer, butyral resin, polyester resin, nitrocellulose, polystyrene, styrene-acrylic copolymer,
Styrene-methacrylic acid copolymer, vinylidene fluoride,
Silicone resin, epoxy resin, styrene-butadiene copolymer, vinyl acetate-methacrylic acid ester copolymer,
Examples thereof include vinyl acetate-crotonate ester copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, urethane resin, stearyl methacryl-chloroprene copolymer, and phenol resin.

Among these insulating resins, resins having a glass transition point of about 40 ° C. or higher, which show particularly high insulating properties, are
In both cases, the triboelectrification polarity when running in a plotter shows a negative polarity or a mixture of positive and negative polarities. In order to make all such triboelectrification polarities positive, the electrostatic recording medium of the present invention contains a specific quaternary ammonium salt compound in the dielectric layer.

Generally, as a compound which imparts positive polarity by triboelectric charging, an electron-donating dye such as a nigrosine dye, which is used as a charge control agent for a developer, an alkoxylated amine which is a nitrogen-containing compound, and a fourth compound Known are ammonium salts, acrylamide, azine compounds, compounds such as phosphorus and tungsten, and triphenylmethane compounds. When these compounds are added to the dielectric layer of the electrostatic recording body, the surface potential shows a weak positive polarity of several volts or less, and even when recording with a color electrostatic plotter, stains due to triboelectric charging are greatly reduced. It However, many of these compounds are colored, and when the colored compound is blended, the whiteness of the recording material decreases.
In addition, a compound having a high water content impairs the insulating property on the surface of the recording material, resulting in a decrease in recording density.

Therefore, in the electrostatic recording material of the present invention, a quaternary ammonium salt compound having a saturated water absorption rate of 1.0% or less under an environment of 30 ° C. and 80% RH is selectively used. Is. The saturated water content in the present invention is 3
It is a value obtained by allowing a quaternary ammonium salt compound to stand for 24 hours in an atmosphere controlled at 0 ° C. and 80% RH, and measuring the weight increase ratio before and after standing. In addition, the quaternary ammonium salt compound includes a polymer electrolyte such as polyvinylbenzyltrimethylammonium chloride that is commonly used in the conductive layer of an electrostatic recording medium, and a surfactant such as a low molecular weight cation-based quaternary ammonium salt. It is known, but generally, most of these compounds have a high saturated water content, and for example, polyvinylbenzyltrimethylammonium chloride, which is commonly used for the conductive layer of an electrostatic recording medium, contains 4 mol% of about 4 mol%.
It is the grade, and shows a value in which the saturated water content in an environment of 30 ° C. and 80 RH exceeds 100%. When such a compound is added to the dielectric layer to such an extent that it is effective in improving stains, a phenomenon in which the image density is reduced is exhibited, and the desired effect of the present invention cannot be achieved.

Therefore, the electrostatic recording material of the present invention exhibits a degree of quaternization of about 10 mol% or less and has a temperature of 30 ° C. and 80 RH.
A quaternary ammonium salt compound having a saturated water content of 1.0% or less under the environment is selectively used. Specific examples of the compound having such characteristics include:
For example, a product name “BONTORON P” manufactured by Orient Chemical Industry Co., Ltd., which is commercially available as a positive charge control agent for developers.
-51 "and the trade name" COPY CHA "manufactured by Hoechst
RGE PSYVP 2038 ”and“ COPYCHARG
E PXVP435 ”and the like. All of these are white, pale white, and pale yellow compounds at 30 ° C.
It is a compound showing a water content of 1.0% or less even when left for 24 hours in an environment of 80% RH.

In the electrostatic recording medium of the present invention, these compounds are added to the dielectric layer to make the triboelectric charging property positive, but the amount of addition is the amount of insulation that constitutes the dielectric layer. Generally, the dielectric layer solid content is 1 depending on the performance of the layer resin.
It is desirable to adjust the amount in the range of about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, relative to 00 parts by weight. By the way, if the addition amount is too small, the desired effect of the present invention cannot be obtained. On the contrary, if the addition amount is too large, crystals of the quaternary ammonium salt compound may be precipitated, or a phenomenon of lowering image density may occur. is there.

In the electrostatic recording medium of the present invention, examples of the pigment constituting the dielectric layer include clay, halosite, hydrohalosite, kaolinite, deckite, nacrite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, Calcined clay, calcined kaolin, amorphous silica,
Alumina, barium sulfate, titanium oxide, various plastic pigments, etc. may be mentioned. The mixing ratio of the pigment is adjusted to be in the range of about 10 to 60% by weight, preferably about 15 to 50% by weight based on the total solid content of the dielectric layer. Incidentally, if it is less than 10% by weight, it becomes difficult to adjust the smoothness of the surface of the obtained recording material to an appropriate region, and conversely 60%.
When the content exceeds the weight%, the recording density may be lowered and white spots may easily occur.

In the electrostatic recording material of the present invention, the dielectric layer is generally a coating solution prepared by dissolving and dispersing an insulating resin or a pigment, for example, a bar coater, a contra coater, a gravure coater, a curtain coater or a chanplex coater. It is formed by a method of coating on a conductive support using an appropriate coating device such as a roll coater or a blade coater. As the conductive support, for example, polyvinylbenzyltrimethylammonium chloride, polydimethylallylammonium chloride, cationic polyelectrolytes such as styrene acrylic acid triethylammonium chloride, polystyrene sulfonate, polyacrylate, polyvinyl phosphate, etc. Anionic polyelectrolyte, or metal semiconductor powder obtained by mixing impurities such as zinc oxide and tin oxide is impregnated or applied with a binder if necessary, and the surface resistance is 10 ⁵ to 10 ^{5.
About 8} ohm paper, plastic film, synthetic paper, Japanese paper, cloth, etc. are appropriately selected and used.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited to these examples. Moreover, the part in an example shows a weight part.

Example 1 [Preparation of Conductive Support] Chemistat 73, which is a cationic polymer electrolyte, is formed on both surfaces of a high-quality paper having a basis weight of 60 g / m ^2.
00 (manufactured by Sanyo Kasei Co., Ltd.) 4 g on the felt side by dry weight
/ M ² , and 2 g / m ^{2 was} applied to the wire side. After that, smoothing treatment was performed with a super calender to obtain a conductive support having a felt side surface smoothness of 300 seconds by a Beck smoother. [Preparation of Electrostatic Recording Body] A dielectric layer-forming coating liquid having the following composition was applied on the felt side of the conductive support in a dry weight of 4 g / m ² to obtain an electrostatic recording body. Toluene / MEK mixed solvent (1/1) 200 parts Calcium carbonate powder (average particle size 5 μm) 35 parts Styrene / n-butyl methacrylate copolymer resin 65 parts Orient Chemical Industry Co., Ltd. positive charge control agent (trade name “BONTORON P-51 "2 copies

Examples 2 and 3 Instead of "BONTRON P-51", a positive charge control agent manufactured by Hoechst (trade name "COPYCHARGE P-
SYVP2038 ") 0.8 parts (Example 2) and the same (trade name" COPYCHARGE PXVP435 ") 5 parts (Example 3), respectively, were used in the same manner as in Example 1 to prepare two types of electrostatic recording materials. Got

Comparative Example 1 An electrostatic recording material was obtained in the same manner as in Example 1 except that "BONTRON P-51" was not added.

Comparative Example 2 An electrostatic recording material was obtained in the same manner as in Example 1 except that polyvinylbenzyltrimethylammonium chloride having a quaternization degree of 20 mol% was used in place of "BONTRON P-51". ..

The five types of electrostatic recording media thus obtained were subjected to the following evaluation tests and the results are shown in Table 1. [Evaluation of recording characteristics] Recording was performed with a color electrostatic plotter [EP-4010] manufactured by Seiko Denshi KK, the recording density of the black image recording portion was measured, and the degree of stain generation on the blank sheet portion was evaluated according to the following evaluation criteria. did. (Evaluation Criteria for Stain Generation) O: Almost no generation. Δ: Slightly generated ×: Occurred all over.

[0023]

[Table 1]

[0024]

As is clear from the results of Table 1, the electrostatic recording materials obtained in the respective examples of the present invention are all electrostatic recording materials having a high recording density and little stains on the white paper portion. It was

Claims (1)

[Claims] 1. An electrostatic recording body comprising a conductive support and a dielectric layer comprising an insulating resin and a pigment as main components formed on the conductive support.
An electrostatic recording material comprising a quaternary ammonium salt compound having a saturated water absorption rate of 1.0% or less under an environment of 30 ° C. and 80% RH in the dielectric layer.