JPH0411262A - Electrostatic recording body - Google Patents

Abstract

PURPOSE:To improve a recording density without degrading practicable use characteristics and recording characteristics by incorporating an alkoxy zirconate coupling agent into a dielectric layer. CONSTITUTION:The dielectric layer contg. an insulating resin and pigment is provided on a conductive base. Further, this dielectric layer contains an alkoxy zirconate coupling agent. The amt. of the alkoxy zirconate coupling agent to be added into the dielectric layer is preferably adjusted in a 1 to 20wt.% range of the whole solid component of the dielectric layer. The electrostatic recording body having the high recording density is obtd. in this way without impairing fixability, practicable usability such as curling and without generating the impaired recording characteristics, such as generation of staining, drop-out of fine lines and abnormal dots.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an electrostatic recording medium suitable for high-density electrostatic plotters such as 400 dots/inch, electrostatic facsimiles, electrostatic printers, and the like.

"Conventional technology" Monochrome and color electrostatic recording methods using multi-needle electrodes are
In recent years, it has become popular as a plotting device for computer graphics output and CAD technology. In order to increase the recording density of the electrostatic recording material used in these electrostatic plotters, the resin forming the dielectric layer must be a homopolymer such as methyl methacrylate or styrene, which has a Tg of 40'C or more. A method of promoting discharge from a multi-needle electrode by using a copolymer containing a large amount of these or a resin copolymerized with a small amount of polar functional groups such as acrylic acid (Japanese Patent Laid-Open No. 50-98324) ) etc. have been proposed.

In addition, as a spacer pigment contained in the dielectric layer, we use pigments with high insulation properties and excellent hydrophobicity, such as calcium carbonate and barium sulfate, which have been made hydrophobic through surface treatment, so that they can be used even under high humidity. maintains good insulation properties,
Methods for obtaining high image density have been proposed.

However, the dielectric layer requires not only recording density but also practical properties such as fixability and curling, so
It was necessary to use a polymer or copolymer such as n-butyl methacrylate or 2-ethylhexyl methacrylate with a Tg below, which resulted in a problem of lowering the insulation properties of the dielectric layer and lowering the recording density. .

Furthermore, recording devices such as high-density electrostatic plotters use pigments with low insulating properties such as kaolin and aluminum hydroxide to reduce deterioration in image quality such as thin lines and abnormal dots, and to prevent friction fog and other problems. Substances that reduce the recording density in the dielectric layer for the purpose of improving image quality and preventing stains, such as conductive pigments and hydrophilic additives, which must be used in combination to prevent stains such as dye stains. At present, an electrostatic recording medium with excellent image quality and sufficient image density has not yet been obtained.

``Problems to be Solved by the Invention'' The problem of the present invention is to obtain an electrostatic recording medium with high recording density without impairing fixing properties, practical suitability such as curling, occurrence of stains, recording characteristics such as missing fine lines and abnormal dots. The purpose is to

"Means for Solving the Problems" The present invention provides an electrostatic recording material in which a dielectric layer containing an insulating resin and a pigment is provided on a conductive support, wherein the dielectric layer further has an alkoxyzirconate coupling. This is an electrostatic recording material characterized by containing an agent.

"Function" In the present invention, the alkoxyzirconate coupling compound contained in the dielectric layer is, for example, a compound exemplified by the following general formula (1).

RO-Z r C0X)s (1) R is H1 or an alkyl group, preferably a neoalkyl group. The alkyl group preferably has 1 to 16 carbon atoms.

X is an acyl group, an alkylbenzenesulfonyl group, a dialkyl phosphate group, a dialkyl birophosphata group,
Examples include alkylene diaminoalkyl groups, aminophenyl groups, and groups into which substituents are introduced.

Specific examples of the alkoxyzirconate coupling agent include the following.

Neoalkoxy tris neodecanoyl zirconate RO, Zr (OCC9HI9) 3 Neoalkoxy tris (dodecyl) benzenesulfonyl zirconate Neo alkoxy tris (dioctyl) phosphate zirconate RO-Z r (OP (OC8H1?) z
) 3 Neoalkoxy-tris(dioctyl)pyrophosphatazirconate H Neoalkoxy-tris(ethylenediamino)ethylzirconate ROZr (OCz Ha NHC2H4NH2) 3 Neoalkoxy-tris(m-amine)phenylzirconate RO-Zr (OCI , )(4NH2L, etc.)

The amount of the alkoxyzirconate coupling agent added to the dielectric layer is adjusted within a range of preferably 1 to 20% by weight, more preferably 1 to 15% by weight of the total solids of the dielectric layer. Incidentally, if the amount added is extremely small, the desired effect of improving the recording density cannot be obtained, and if it is extremely large, the effect of improving the recording density will not only reach a saturation point but also cause problems such as thickening or gelation of the paint. Harmful effects may occur. In addition, in order to prevent thickening of the paint, it is also a good method to selectively attach an alkoxyzirconate coupling agent to the surface of the pigment contained in the dielectric layer, or to treat the surface by reacting with the pigment. Specifically, there is a method in which an alkoxyzirconate coupling agent is dissolved in a solvent such as toluene or xylene, and the solution is applied to the surface of a pigment and then dried. In this case, the amount of the alkoxyzirconate coupling agent used is preferably in the range of 0.01% to 10% by weight based on the pigment used.

Examples of pigments to be contained in the dielectric layer include clay, hallosite, hydrated hallosite, kaolinite, detsuite, natalite, aluminum hydroxide, calcium carbonate,
Calcined clay, calcined kaolin, amorphous silica, alumina,
Examples include barium sulfate and titanium oxide.

The weight ratio of the pigment and the insulating resin constituting the dielectric layer is not particularly limited, but is adjusted within a range of about 5:95 to 70:30, preferably about 10:90 to 50:50.

If the blending ratio of the pigment is extremely low, the gloss of the surface of the recording medium increases to such an extent that it impairs its natural appearance. On the other hand, if the amount is too high, the recording density may decrease. In addition, if the average particle diameter of the pigment is too large, it will be difficult to maintain the gap between the recording medium surface and the multi-needle electrode at an appropriate distance, resulting in all marks (black solid).
If it is too small, partial unevenness in recording density will occur when recording all marks, so it is preferably 1 to 15 μm, more preferably 2 to 15 μm.
A pigment having an average particle size of about 10 μm is used.

Examples of the insulating resin contained in the dielectric layer include methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate,
Polymers and copolymers of acrylic esters and methacrylic esters such as isobutyl methacrylate and 2-ethylhexyl methacrylate, and acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid, acrylonitrile, and methacrylonitrile. mi, polyvinyl acetate, ethylene, etc., copolymerized with monomers having functional groups such as
Vinyl acetate copolymer, butyral resin, polyester resin, nitrocellulose resin, polystyrene, styrene・
Acrylic copolymer, styrene/methacrylic acid copolymer,
Vinylidene fluoride resin, silicone resin, epoxy resin,
Examples include urethane resin and phenol resin.

Dielectric material Ji is generally prepared using a coating liquid made by dissolving or dispersing an insulating resin or pigment in an organic solvent such as toluene, methyl ethyl ketone, xylene, or isopropyl alcohol using a bar coater, contra coater, gravure coater, curtain coater, champlex coater, or roll coater.
It is formed by coating on a conductive support using various coating devices such as a blade coater.

Examples of the conductive support constituting the electrostatic recording medium include cationic polymer electrolytes such as polyvinylbenzyltrimethylammonium chloride, polydimethylallylammonium chloride, styrene acrylic acid triethylammonium chloride, polystyrene sulfonate, and polyacrylic acid. acid salts, anionic polymer electrolytes such as polyvinyl phosphate, or zinc oxide, tin oxide,
Paper, plastic film, synthetic paper, Japanese paper, cloth, etc. impregnated or coated with metal semiconductor powder mixed with impurities, etc., along with the binding side as necessary, to have a surface resistance of about 10' to 10' Ω. is used.

"Examples" Examples of the present invention will be described below, but the present invention is not limited to these Examples.

Moreover, parts in the examples represent parts by weight.

Example 1 [Preparation of conductive support] A cationic polymer electrolyte was placed on high-quality paper with a basis weight of 60 g/m''
Apply styrene methacrylate ethyltrimethylammonium chloride (manufactured by Sanyo Chemical Co., Ltd., Chemistat 7300) at a dry weight of 4 g/m" on the front side and 2 g/m" on the back side, and smooth it so that the Beck smoothness is 700 seconds. A conductive support was obtained.

[Preparation of electrostatic recording medium]

An electrostatic recording material was obtained by coating a dielectric layer coating liquid having the following composition on the above support at a dry weight of 4 g/m.The coating liquid was prepared by dispersing kaolin in toluene, It was prepared by adding a resin and then adding and mixing an alkoxyzirconate coupling agent.

[Composition of dielectric layer coating liquid] Toluene 200 parts Kaolin (average particle size 4 μm) 20 parts Calcium carbonate (average particle size 3 μm) 20 parts Methyl methacrylate resin 40 parts n-butyl methacrylate resin 20 parts Neoalkoxy tris neodecanoyl Zirconite 1
0 parts Example 2 Example 1 except that aluminum hydroxide (average particle size 8 μm) was used instead of kaolin (average particle size 4 μm)
An electrostatic recording medium was obtained in the same manner as above.

Example 3 A dielectric layer coating solution was prepared by mixing the following materials.

Toluene 200 parts Calcium carbonate (average particle size 3.5 μm) 40 parts Amorphous silica (average particle size 1.5 μm) 5 parts Styrene/butyl methacrylate/methyl methacrylate copolymer 55 parts A dielectric layer coating solution was prepared by adding and mixing 5 parts of neoalkoxy-tris(dodecyl)benzenesulfonyl zirconate.

This coating liquid was coated on a conductive support and dried in the same manner as in Example 1 to obtain an electrostatic recording material.

Example 4 Aluminum hydroxide (average particle size 8.0 microns) 1
00 parts were placed in a mortar and 10 parts of a 10% toluene solution of neoalkoxy-tris(dioctyl)phosphate zirconate was added little by little while stirring to perform a pigment surface treatment and drying.

[Composition of dielectric layer coating liquid]

Toluene 200 parts Aluminum hydroxide subjected to the above surface treatment 20 parts Calcium carbonate (average particle size 3 μm) 20 parts Methyl methacrylate resin 40 parts N-butyl methacrylate resin 20 parts Same as Example 1 except that the above dielectric layer coating liquid was used. An electrostatic recording medium was obtained.

Comparative Examples 1 to 3 Three types of electrostatic recording were carried out in the same manner as in Examples 1 to 3, except that no alkoxyzirconate coupling agent was added in the preparation of the dielectric layer coating solutions of Examples 1 to 3. I got a body.

Comparative Example 4 An electrostatic recording material was obtained in the same manner as in Example 4 except that unsurface-treated aluminum hydroxide was used instead of the surface-treated aluminum hydroxide.

The following quality evaluation tests were conducted on the various types of electrostatic recording bodies thus obtained. Recording was performed using a color electrostatic plotter (manufactured by Xerox Corporation, CE3424), and the recorded density of the black pattern portion was measured using a Maches densitometer, and the results shown in Table 1 were obtained.

The recording fixing properties, curling, and bronking resistance of the electrostatic recording materials obtained in each example were the same as those of the electrostatic recording materials to which no alkoxyzirconate coupling agent was added.
It had good quality.

Table 1 "Effects" As is clear from the results in Table 1, the electrostatic recording materials obtained in each example of the present invention had a remarkable recording density without deteriorating the practical characteristics or recording characteristics. It has been improved and is an extremely well-balanced record in terms of quality.

Claims (1)

[Scope of Claims] An electrostatic recording material comprising a dielectric layer containing an insulating resin and a pigment provided on a conductive support, characterized in that the dielectric layer further contains an alkoxyzirconate coupling agent. An electrostatic recording medium.