JPH10186685A - Electrostatic recording medium - Google Patents

Abstract

(57) [Abstract] The present invention relates to an electrostatic recording medium, and more particularly, to an electrostatic recording medium having excellent environmental resistance, and capable of obtaining a clear, high-density, and high-definition color image. A recording medium is provided. The present invention provides an electrostatic recording medium comprising: a conductive layer containing an electron conductive pigment; and a recording layer containing styrene or acrylic resin particles, which are sequentially laminated on a support.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording medium, and more particularly, to an electrostatic recording medium having excellent environmental resistance and capable of obtaining a clear, high-density and high-definition color image. To provide.

[0002]

2. Description of the Related Art Conventionally, an electrostatic recording system using an electrostatic recording medium has been used in various fields such as facsimile, drafting, newspaper proofreading, and official document recording. Accordingly, color recording-compatible devices have been developed, and as a result, color copies can be easily obtained in fields such as design-related, event-related, and advertising-related fields. In particular, the electrostatic recording method has been adopted for large color copying because of its processing speed and high definition. Against this background, these applications require higher-definition images compared to facsimile machines, etc., and even clearer, higher-density, more precise, and higher-definition images faithful to the original image in color images. It has been demanded.

The recording layer in a conventional electrostatic recording medium is composed of polystyrene, polyester, polymethacrylate,
It has a structure in which inorganic pigments such as silica, clay, alumina, and calcium carbonate are dispersed in a binder having a high dielectric constant such as polyvinyl acetate in order to improve air discharge characteristics. These pigment components are poor in moisture resistance, and have a problem that when recording is performed in a high-humidity atmosphere, the image density is low or image bleeding occurs. In addition, in order to improve such high humidity characteristics, polyethylene,
It has also been proposed to use resin particles such as polypropylene and silicone resin in place of the above-mentioned inorganic pigments.However, an electrostatic recording medium provided with such a recording layer causes rough or missing images, A clear high-density image could not be obtained, and there was a problem in image characteristics.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention provides an electrostatic recording medium having excellent image characteristics capable of obtaining a clear, high-density, high-definition color image under a wide range of environmental conditions. Things.

[0005]

According to the present invention, a conductive layer containing an electron conductive pigment and a recording layer containing styrene or acrylic resin particles are sequentially laminated on a support. An electrostatic recording medium characterized by the following.

The styrene or acrylic resin particles used in the present invention include styrene, styrene such as vinyl toluene, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methacrylic acid. Includes homopolymers or copolymers of acrylic monomers such as methyl, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, or other monomer components that can be copolymerized with the above monomer components as main components. And spherical particles composed of a crosslinked polymer or a crosslinked copolymer using a crosslinking agent in place of other monomer components.

In the present invention, the particle size of the resin particles as described above is not particularly limited, but particles of 0.5 to 15 μm are suitable, and 2 to 12 μm is particularly preferable. Use of particles having a particle size of less than 0.5 μm tends to cause image omission or the like, and use of particles having a particle size of more than 15 μm tends to cause image roughness or the like, which may impair image uniformity. The content of the resin particles in the recording layer is preferably 1 to 15% by weight, particularly preferably 2 to 9% by weight. Content of acrylic resin particles is 1% by weight
If it is less than 1, the uniform unevenness on the surface of the recording layer is reduced, and the image becomes rough or missing, and a high-definition image cannot be obtained. Further, if the content exceeds 15% by weight, not only the effect cannot be obtained on a high-definition image, but also a sufficient clear density cannot be obtained, that is, the image density may be reduced.

In the present invention, the above-mentioned resin particles made of a crosslinked resin are particularly preferable since a clear, high-density image can be obtained without image roughness or dropping under a wide range of environmental conditions. Such a cross-linked resin, the degree of cross-linking is not particularly limited, water, alcohol,
Those crosslinked to such an extent that they do not swell at all or hardly in organic solvents such as toluene and methyl ethyl ketone are applied.

The recording layer in the present invention is obtained by dispersing the above resin particles in a resin. As such a resin, various resins having a large insulation resistance can be used, for example, vinyl chloride resin, vinyl acetate resin, acrylic resin, polyester resin, urethane resin, butyral resin, nitrocellulose, styrene resin, silicone resin, olefin resin and the like. No. If necessary, use inorganic pigments or organic pigments such as calcium carbonate, magnesium carbonate, titanium oxide, magnesium oxide, hydroxyl number aluminum, zinc oxide, silica, polypropylene particles, and silicone resin particles as long as the effects of the present invention are not impaired. be able to.

As the conductive layer in the present invention, a conductive layer using at least an electron conductive pigment as a conductive agent is applied.
As the electron conductive pigment, a needle-like or particle-like pigment having a conductive inorganic pigment, that is, an inorganic pigment as a base material, the surface of which is coated with a conductive substance, is used. Here, the acicular conductive pigment is potassium titanate, titanium oxide, barium sulfate,
The base material is aluminum borate, calcium carbonate, etc., the surface of which is coated with antimony, tin oxide, etc.
Those having a shape of from 40 to 40 μm and a minor axis of from 0.05 to 3 μm are preferable because good conductivity is obtained. If the major axis is less than 1 μm, the coating amount of antimony and tin oxide on the surface of the base material must be increased in order to obtain desired conductivity, and the whiteness is inevitably reduced. If the major axis exceeds 40 μm, depending on the base material, the shearing force at the time of dispersion of the paint tends to break the needle-like crystals, leading to a decrease in conductivity, causing problems such as unstable dispersion conditions and paint properties during production. In addition, the particulate conductive pigment has a base material of zinc oxide, titanium oxide, calcium carbonate, calcium sulfate, or the like, and is coated with antimony, tin oxide, or aluminum, and has a particle diameter of 0.1 to 20 μm.
Is preferred since good conductivity can be obtained.

The conductive layer is formed using the above-mentioned electron conductive pigment and a binder. As the binder used here, vinyl chloride resin, vinyl acetate resin, acrylic resin, polyester resin, urethane resin, butyral resin, nitrocellulose, styrene butadiene copolymer, polyvinyl alcohol, hydroxyethyl cellulose, gelatin, starch, Water-soluble resin such as casein,
Although a water-dispersible resin and an organic solvent-based resin can be appropriately selected and used, a water-soluble or water-dispersible resin is preferable since stable conductivity is obtained and the productivity is good.

The combination of the electron conductive pigment and the binder in the conductive layer is appropriately determined depending on the materials used, and the surface resistance of the conductive layer is 1.0 × 10 ^{5 to} 1.0 × 10 ^9.
Although it is prepared so as to be Ω / □, in the case of the acicular conductive pigment, it is preferable that the blending amount of the binder is 70 to 400 parts by weight with respect to 100 parts by weight of the pigment. If the amount of the binder is more than 400 parts by weight, the resistance increases and the conductive properties are impaired. On the other hand, if the amount is less than 70 parts by weight, not only the effect of improving the conductive properties is not seen but also the image density may be lowered. Further, in the case of the particulate conductive pigment, the content of the binder is 5 to 70 parts by weight with respect to 100 parts by weight of the pigment.
It is preferred to use parts by weight. If the amount of the binder is more than 70 parts by weight, the resistance is increased and the conductive properties are impaired.
When the amount is less than the weight part, the binding property and the film forming property of the conductive layer are hindered.

The conductive layer in the present invention has the above composition, but if necessary, an ion conductive substance such as a cationic polymer electrolyte or an anionic polymer electrolyte can be used in combination as a conductive agent. . However, even when such a conductive agent is used in combination with the recording layer of the present invention, it is inferior in humidity resistance and may cause problems in image characteristics such as image dropout and image density reduction. Is preferred.

The support in the present invention can be, for example, paper, synthetic paper, nonwoven fabric, various resin films, cloth, leather, etc., and is not particularly limited. The electrostatic recording medium of the present invention is produced by laminating a recording layer on the above-mentioned support provided with the conductive layer on at least one surface. In order to provide the conductive layer and the recording layer in the present invention, for example, the above material is dissolved or dispersed in a solvent such as water, alcohol, toluene, methyl ethyl ketone, and ethyl acetate to form a paint, an air knife coater, a color roll coater. It can be provided by coating and drying sequentially on a support with a wire bar coater or the like.

In the conductive support and the electrostatic recording medium of the present invention, if necessary, (1) when a conductive layer is provided only on one side, between the support and the conductive layer, and (2) When the conductive layer is provided on both surfaces of the support,
A barrier layer can be provided on at least one of the support and the conductive layer. The barrier layer is, for example, a styrene-butadiene copolymer, an acrylic-acrylate copolymer, a styrene-acryl copolymer,
Various emulsion resins such as a vinyl chloride-vinyl acetate copolymer are suitable, but not limited thereto, and various known resins may be used. In addition, you may use together an inorganic pigment, an organic pigment, a conductive pigment, etc. as needed.

[0016]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The number of parts indicating the composition in each Example and Comparative Examples is
All parts are by weight. Example 1 A high-grade paper having a basis weight of 64 g / m ² was used as a support, and a coating for a conductive layer having the following composition was applied to both surfaces of the support and dried to form a conductive layer having a coating amount of 5 g / m ^2. Provided. This was calendered, and the surface smoothness of the conductive layer was adjusted to 400 to 500 seconds with an Oken type smoothness meter. <Conductive layer application fee> ・ Acicular conductive pigment (Dentor WK-300, 40 parts, manufactured by Otsuka Chemical Co., Ltd., 40 parts, major axis: 10-20 μm, minor axis: 0.2-0.5 μm) ・ Starch (Matsuya Chemical Co., unique Gum P3010) 60 parts ・ Water 400 parts

On one surface of the above-mentioned conductive layer, a coating material for a recording layer having the following composition is applied and dried to give a coating amount of 4 g / m ^2.
Was provided to produce an electrostatic recording medium of the present invention. <Coating for recording layer>-490 parts of polyester resin (manufactured by Toyobo Co., Byron 200, solid content 40%)-Styrene resin particles (manufactured by Sekisui Plastics Co., Ltd., 4 parts of Techpolymer SBX-8, particle size 8 µm)-Toluene 160 parts

Example 2 An electrostatic recording medium of the present invention was produced in the same manner as in Example 1 except that a recording layer paint having the following composition was used. <Coating for recording layer>-460 parts of polyester resin (manufactured by Toyobo Co., Byron 200, solid content 40%)-Styrene resin particles (manufactured by Sekisui Plastics Co., Ltd., 18 parts of Techpolymer SBX-8, particle size 8 m)-Toluene 190 copies

Example 3 An electrostatic recording medium of the present invention was prepared in the same manner as in Example 1, except that a coating material for a recording layer having the following composition was used. <Coating for recording layer>-470 parts of polyester resin (manufactured by Toyobo Co., Byron 200, solid content 40%)-10 parts of acrylic resin particles (manufactured by Soken Chemical Co., MR-7G, particle size 5 m)-10 parts-180 parts of toluene

Example 4 An electrostatic recording medium of the present invention was produced in the same manner as in Example 1 except that a recording layer paint having the following composition was used. <Coating for recording layer> ・ 470 parts of polyester resin (manufactured by Toyobo Co., Byron 200, solid content 40%) ・ 10 parts of acrylic resin particles (manufactured by Soken Chemical Co., MR-10G, particle size 9 μm) ・ 180 parts of toluene

Example 5 A coating amount of 10 g was applied using a conductive layer paint having the following composition.
An electrostatic recording medium of the present invention was produced in the same manner as in Example 1 except that the value was / m ² . <Coating for conductive layer> 100 parts of conductive zinc oxide (manufactured by Hakusui Chemical Co., 23-K, particle size 0.2 μm) 100 parts ・ 10 parts of polyvinyl alcohol (manufactured by Kuraray, PVA105) ・ 190 parts of water

Example 6 A coating amount of 10 g was applied using a conductive layer paint having the following composition.
An electrostatic recording medium of the present invention was produced in the same manner as in Example 3, except that the value was set to / m ² . <Coating for conductive layer> 100 parts of conductive zinc oxide (manufactured by Hakusui Chemical Co., 23-K, particle size 0.2 μm) 100 parts ・ 10 parts of polyvinyl alcohol (manufactured by Kuraray, PVA105) ・ 190 parts of water

Comparative Example 1 A coating amount of 7 g /
except that the m ² was fabricated electrostatic recording material for comparison in the same manner as in Example 1. <Coating for conductive layer> Cationic polymer electrolyte (manufactured by Sanyo Chemical Industries, Chemistat 270, 6300, solid content 33%) Starch (Matsuya Chemical Co., unique gum P3010) 15 parts Calcium carbonate (Bibihoku Company, Softon 1000) 45 parts ・ Water 170 parts

Comparative Example 2 An electrostatic recording medium for comparison was prepared in the same manner as in Example 1 except that a coating material for a recording layer having the following composition was used.・ 470 parts of polyester resin (manufactured by Toyobo Co., Byron 200, solid content 40%) ・ Polypropylene resin particles (manufactured by Mitsui Petrochemical Industries, 70 parts Unistor R100, solid content 15%) ・ Toluene 120 parts

Comparative Example 3 An electrostatic recording medium for comparison was prepared in the same manner as in Example 1 except that a coating material for a recording layer having the following composition was used.・ 470 parts of polyester resin (manufactured by Toyobo Co., Byron 200, solid content 40%) ・ 10 parts of silicone resin particles (manufactured by Toshiba Silicone Co., Tospearl 145) ・ 180 parts of toluene

Comparative Example 4 An electrostatic recording medium for comparison was prepared in the same manner as in Example 1 except that a coating material for a recording layer having the following composition was used.・ 450 parts of polyester resin (manufactured by Toyobo Co., Byron 200, solid content 40%) ・ 20 parts of calcium carbonate (manufactured by Bihoku Powder Chemical Co., Ltd., Softon 1200) ・ 200 parts of toluene

The electrostatic recording media of Examples 1 to 6 and Comparative Examples 1 to 4 produced above were subjected to environmental conditions of 20 ° C.3 using an electrostatic plotter (CE3436 manufactured by Versatech Co.).
At 0% RH, 22 ° C. 60% RH, 25 ° C. 70% RH,
Each image was subjected to full-color recording, and the obtained images were evaluated. In the evaluation, the image density was measured using a Macbeth densitometer RD914 to measure the black portion, and the image quality was evaluated by visual inspection when there was no image quality defect such as image roughness or dropout, and at least one of the image quality defects was slightly recognized. The sample was rated as ○, the one that was recognized to the extent that there was no practical problem was rated as △, and the one that was recognized to some extent was a practical problem. The evaluation results are as shown in Table 1, and it was confirmed that the electrostatic recording medium of the present invention had stable image characteristics in a wide range of environments.

[0028]

[Table 1]

[0029]

The electrostatic recording medium of the present invention has excellent image characteristics such that a clear, high-density, high-definition image can be obtained under a wide range of environmental conditions as described above, and good recording characteristics are obtained. Yes, it can be suitably used for color recording.

Claims (5)

[Claims] 1. An electrostatic recording comprising a conductive layer containing an electron-conductive pigment and a recording layer containing styrene-based or acrylic-based resin particles sequentially laminated on a support. body. 2. The electrostatic recording medium according to claim 1, wherein the styrene-based or acrylic-based resin particles are a crosslinked resin. 3. The electrostatic recording medium according to claim 1, wherein said conductive layer comprises a needle-like conductive pigment and an aqueous binder. 4. The electrostatic recording medium according to claim 1, wherein said styrene or acrylic resin particles have a particle size of 0.5 to 15 μm. 5. The electrostatic recording medium according to claim 1, wherein the content of the styrene or acrylic resin particles is 1 to 15% by weight.