JPH1048865A - Conductive support and electrostatic recording medium using the same - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a conductive support, which exhibits stable conductivity over a wide range of environmental conditions.
A conductive support on which a conductive layer having excellent humidity resistance to obtain good recording characteristics and having an excellent whiteness suitable for color recording is formed, and an electrostatic recording material using the same. Is provided. A conductive layer containing a needle-like conductive pigment and a metal hydroxide is provided on at least one surface of a substrate, and a metal hydroxide is added to 100 parts by weight of the needle-like conductive pigment.
A conductive support, wherein the recording layer is formed on a conductive layer of the conductive support.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive support, which exhibits stable conductivity over a wide range of environmental conditions, has excellent humidity resistance for obtaining good recording characteristics, and has a color. An object of the present invention is to provide a conductive support on which a conductive layer having excellent whiteness, which can be suitably used for recording, is formed, and an electrostatic recording medium using the same.

[0002]

2. Description of the Related Art Conventionally, a recording layer (a photoconductive layer in an electrophotographic photosensitive member,
A conductive support is used as a support for providing a dielectric layer in an electrostatic recording medium.

An electrostatic recording system using an electrostatic recording medium has been used in various fields such as facsimile, drafting, newspaper proofing, and official document recording. Corresponding devices have been developed, and along with this, color copies can be easily obtained in fields such as design-related, event-related, and advertising-related fields. In particular, the electrostatic recording method is used for large-sized color copying in terms of processing speed and high definition. From such a background, a conductive support having a high whiteness of the recording layer surface capable of obtaining an excellent color image, having excellent humidity resistance characteristics in which good recording characteristics can be obtained under a wide range of environmental conditions, And an electrostatic recording medium using the same.

Conventional conductive supports cover the surface of a base material with an electronically conductive metal oxide semiconductor in order to reduce the change in conductivity so that good recording characteristics can be obtained under a wide range of environmental conditions. The used conductive pigment is used. In particular, needle-like ones can provide excellent conductivity with excellent humidity resistance stability with a small amount of addition compared to particle-like ones, and have the effect of suppressing the decrease in whiteness due to the above coating to some extent. From
It has been commonly used.

However, since these conductive pigments are coated with at least a metal oxide semiconductor, their whiteness is impaired even when a white pigment is used as a base material, and there is a problem in application to color recording. Was something. Further, while the needle-shaped conductive pigment provides good conductivity, it is not sufficiently satisfactory in recording characteristics that the formed image is liable to cause poor solid uniformity and horizontal leakage.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention maintains an excellent conductivity of a needle-shaped conductive pigment with excellent moisture resistance stability, has an excellent solid uniformity, and is free from lateral leakage. It is an object of the present invention to provide a conductive support having improved recording properties and improved whiteness suitable for color recording, and an electrostatic recording medium using the same.

[0007]

According to the present invention, a conductive layer containing a needle-like conductive pigment and a metal hydroxide is provided on at least one surface of a substrate, and 100 parts by weight of the needle-like conductive pigment is provided. A conductive support, characterized in that the metal hydroxide is 5 to 300 parts by weight with respect to the conductive support, and further, an electrostatic recording body having a recording layer formed on a conductive layer of the conductive support. .

The acicular conductive pigment used in the present invention is, for example, tin oxide containing potassium titanate, titanium oxide, barium sulfate, aluminum borate, calcium carbonate or the like as a base material and the surface of which contains antimony as an impurity. It has a needle shape with a major axis of 1 to 40 μm, a minor axis of 0.05 to 3 μm, preferably a major axis of 2 to 25 μm, and a minor axis of 0.05 to 1 μm. When the major axis is less than 1 μm,
In order to obtain the desired conductivity, the coating amount of antimony and tin oxide on the surface of the base material must be increased, and the whiteness inevitably decreases. If the major axis exceeds 40 μm, the needle-like crystal is easily broken due to the shearing force at the time of dispersing the paint, depending on the base material, leading to a decrease in conductivity, causing a problem of unstable dispersion conditions and paint properties during production. Further, it is desirable that the ratio of the size of the major axis to the minor axis is 10 or more, preferably 20 or more in order to achieve conductivity excellent in humidity resistance stability. The size of the particles of the acicular conductive pigment and the metal hydroxide described below is an average value observed by an electron microscope.

In the present invention, as the metal hydroxide used in the conductive layer together with the acicular conductive pigment, those having spherical or amorphous white particles are applied, and in particular, the general formula M (OH)
a metal hydroxide represented by n (n is an integer of 2 to 4) and M is an alkaline earth metal, aluminum, titanium or zinc, for example, Ca (OH) ₂ , Mg (OH) ₂ , Zn
(OH) ₂ , Al (OH) ₃ , Ti (OH) _{4 and the} like are preferred.
The size of the particles composed of such a metal hydroxide is not particularly limited, but those having an average particle size of 0.05 to 3 μm are particularly preferred. Average particle size is 0.05μm
If it is less than 3 μm, excellent recording properties may not be obtained. If it is more than 3 μm, the required humidity resistance may be obtained by inhibiting the contact of the acicular conductive pigment or reducing the smoothness of the conductive layer coated surface. There is a possibility that the required conductivity may not be obtained because the barrier property of the conductive layer is inhibited and the uniform formation of the conductive layer is inhibited.

In the present invention, the metal hydroxide is mixed in an amount of 5 to 300 parts by weight, preferably 30 to 250 parts by weight, particularly preferably 50 to 200 parts by weight, based on 100 parts by weight of the acicular conductive pigment. It must be contained in the conductive layer in a proportion. If the metal hydroxide content is less than 5 parts by weight, the whiteness required for color recording (80% or more, JISP8123
) Cannot be obtained, and recording characteristics such as solid uniformity and horizontal slippage are impaired. Conversely, if the metal hydroxide is 30
When used in excess of 0 parts by weight, the conductivity of the acicular conductive pigment is impaired, resulting in a problem that the resistance value increases and the humidity resistance stability is impaired.

The conductive layer in the present invention is formed by dispersing the acicular conductive pigment and the metal hydroxide as described above in a binder. Examples of the binder include vinyl chloride resin, vinyl acetate resin, acrylic resin, polyester resin, urethane resin, butyral resin, nitrocellulose, styrene butadiene copolymer, polyvinyl alcohol, hydroxyethyl cellulose, gelatin, starch, casein, and the like. A water-soluble or water-dispersible water-based resin or an organic solvent-based resin is appropriately used, but the water-based resin is preferable in view of the dispersibility and production of the acicular conductive pigment and the metal hydroxide. In dispersing the pigment, a dispersant or the like can be used. The blending amount of the binder is 5 with respect to 100 parts by weight of the combined amount of the acicular conductive pigment and the metal hydroxide.
The amount is preferably from 0 to 300 parts by weight from the viewpoint of conductivity having good humidity resistance and coatability of the conductive layer.

In the conductive layer of the present invention, white pigments such as calcium carbonate, magnesium carbonate, titanium oxide, magnesium oxide, aluminum oxide, zinc oxide and silica are used in combination within a range not to impair the required humidity resistance. Can further improve the whiteness. In addition, in order to improve the luminous white, a fluorescent dye is added to the conductive layer paint at 0.5 to 0.5%.
12% by weight can be added.

The conductive layer having the above composition has a surface smoothness (according to JISP8119) of 150 seconds or more.
It is preferably from 250 to 1000 seconds in order to achieve excellent recording characteristics. Such smoothness can be appropriately controlled by a calendar process or the like.
Further, the surface resistance of the conductive layer is 1.0 × 10 ^{4 to} 1.0 × 1.
It is preferable from the viewpoint of recording characteristics to be adjusted to ⁰⁹ Ω / □.

The substrate in the present invention includes, for example, paper, synthetic paper, nonwoven fabric, various resin films, cloth, leather and the like. The conductive support of the present invention is obtained by providing the above-described base on at least one surface thereof with the above-described conductive layer.

Further, the electrostatic recording medium of the present invention is one in which a recording layer is provided on the conductive layer of the above-mentioned conductive support. In the case of a conductive support in which conductive layers are provided on both surfaces of a substrate, a recording layer is provided only on one surface of the conductive layer.
As the recording layer, various resins having a large insulation resistance having a function as a dielectric layer 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 can be mentioned. Pigments such as calcium carbonate, magnesium carbonate, titanium oxide, magnesium oxide, aluminum hydroxide, zinc oxide, silica, polypropylene particles, and silicone resin particles are dispersed in these various resins having large insulation resistance to form a recording layer. .

In order to provide the conductive layer and the recording layer in the present invention, for example, the above-mentioned materials are dissolved or dispersed in a solvent such as water, alcohol, toluene, methyl ethyl ketone, ethyl acetate or the like to form a paint.
It can be provided by sequentially coating and drying on a substrate by a color roll coater, 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 surface, the conductive layer is provided between the base and the conductive layer, and (2) When a conductive layer is provided on both sides of the base, a barrier layer can be provided on at least one of the base and the conductive layer. The barrier layer is preferably, for example, various emulsion resins such as styrene-butadiene copolymer, acryl-acrylate copolymer, styrene-acryl copolymer, vinyl chloride-vinyl acetate copolymer, and the like. Various known resins are used without limitation. If necessary, an inorganic pigment, an organic pigment, a conductive pigment or the like may be used in combination. Incidentally, the conductive support of the present invention,
It is used not only for the electrostatic recording medium as described above, but also for, for example, an electrophotographic photosensitive member, an electrophotographic lithographic printing original plate, and the like.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The number of parts indicating the composition in each Example and Comparative Examples is
All parts are by weight. Example 1 Using a high-quality paper having a basis weight of 64 g / m ² as a substrate, a coating for a conductive layer having the following composition was applied and dried on both surfaces of the substrate to provide a conductive layer having a coating amount of 5 g / m ^2. The conductive support of the present invention was produced.・ Acne-shaped conductive pigment 25 parts (Tin oxide coated with tin oxide, manufactured by Ishihara Sangyo Co., Ltd., FT-3000, major axis 3-6 μm, minor axis 0.05-0.1 μm) ・ Al (OH) ₃ 25 parts (Showa Denko's Heidilite H-32 adjusted to 2 µm with an attritor) ・ Starch (Matsuya Chemical Co., Unique Gum P3010) 50 parts ・ Water 400 parts

Example 2 Example 1 except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced. -45 parts of acicular conductive pigments (FT-3000, manufactured by Ishihara Sangyo)-5 parts of Al (OH) ₃ (adjusted Heidilite H-32 manufactured by Showa Denko to 2 µm with an attritor)-Starch (Matsuya Chemical Co., Ltd., Unique Gum P3010) 50 parts ・ Water 400 parts

Example 3 Example 1 except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced.・ Acicular conductive pigment (FT-3000, manufactured by Ishihara Sangyo Co., Ltd.) 15 parts ・ Al (OH) ₃ 35 parts (Heidilite H-32 manufactured by Showa Denko KK was adjusted to 2 μm by an attritor) ・ Starch (Matsuya Chemical Co., Ltd., Unique Gum P3010) 50 parts ・ Water 400 parts

Example 4 Example 1 except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced.・ Acicular conductive pigment (Ishihara Sangyo Co., Ltd., FT-3000) 30 parts ・ Al (OH) ₃ 30 parts (Showa Denko Co., Ltd. Heidilite H-32 adjusted to 2 μm with an attritor) ・ Starch (Matsuya Chemical Co., Ltd., Unique Gum P3010) 40 parts ・ Water 400 parts

Example 5 Example 1 was conducted except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced.・ Acicular conductive pigment (FT-3000, manufactured by Ishihara Sangyo) 20 parts ・ Al (OH) ₃ 10 parts (Heidilite H-32 manufactured by Showa Denko KK was adjusted to 2 μm by an attritor) ・ Starch (Matsuya Chemical Co., Ltd., Unique Gum P3010) 70 parts ・ Water 400 parts

Example 6 Example 1 was conducted except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced.・ 25 parts of acicular conductive pigment (FT-3000, manufactured by Ishihara Sangyo Co.) ・ 25 parts of Al (OH) ₃ (adjusted to 0.5 μm with Heidilite H-32 manufactured by Showa Denko KK)・ Starch (Matsuya Chemical Co., unique gum P3010) 50 parts ・ Water 400 parts

Example 7 Example 1 except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced. · Acicular conductive pigment 25 parts (potassium titanate was tin oxide coated, Otsuka Chemical Co., DENTALL WK -300, major axis 10 to 20 [mu] m, minor axis _{0.2~0.5μm) · Al (OH) 3} 25 Part (Heidilite H-32 manufactured by Showa Denko KK adjusted to 2 μm by an attritor) ・ Starch (Matsuya Chemical Co., unique gum P3010) 50 parts ・ Water 400 parts

Example 8 Example 1 except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced.・ 25 parts of acicular conductive pigment (FT-3000, manufactured by Ishihara Sangyo Co., Ltd.) ・ 25 parts of Al (OH) ₃ (Heidilite H-32, manufactured by Showa Denko KK, particle size 3.5 μm is used as it is) ・ Starch ( Matsuya Chemical Co., Ltd., Unique Gum P3010) 50 parts ・ Water 400 parts

Example 9 Example 1 was repeated except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support of the present invention was produced.・ 25 parts of acicular conductive pigment (FT-3000, manufactured by Ishihara Sangyo) ・ 25 parts of Al (OH) ₃ (Heidilite H-32 manufactured by Showa Denko adjusted to 0.03 μm by an attritor)・ Starch (Matsuya Chemical Co., unique gum P3010) 50 parts ・ Water 400 parts

Comparative Example 1 Example 1 was repeated except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support for comparison was produced. -Acicular conductive pigment (Ishihara Sangyo Co., Ltd., FT-3000) 40 parts-Starch (Matsuya Chemical Co., Ltd., Unique Gum P3010) 60 parts-Water 400 parts

Comparative Example 2 Example 1 except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support for comparison was produced. -Acicular conductive pigment (FT-3000, manufactured by Ishihara Sangyo Co., Ltd.) 10 parts-Al (OH) ₃ 40 parts (Heidilite H-32 manufactured by Showa Denko KK was adjusted to 2 µm by an attritor)-Starch (Matsuya Chemical Co., Ltd., Unique Gum P3010) 50 parts ・ Water 400 parts

Comparative Example 3 Example 1 except that a paint for a conductive layer having the following composition was used.
In the same manner as in the above, a conductive support for comparison was produced.・ Acicular conductive pigment (Dentor WK-300, manufactured by Otsuka Chemical Co., Ltd.) 40 parts ・ Starch (Matsuya Chemical Co., unique gum P3010) 60 parts ・ Water 400 parts

Comparative Example 4 Al (OH) ₃ in the coating material for the conductive layer of Example 1 was replaced with calcium carbonate (Softon 1200, manufactured by Bihoku Powder Chemical Industry Co., Ltd., particle size: 1.
A conductive support for comparison was prepared in the same manner as in Example 1 except that the thickness was changed to 8 μm).

Comparative Example 5 Al (OH) ₃ in the coating material for the conductive layer in Example 1 was replaced with zinc oxide (SAZEX # 2000, manufactured by Sakai Chemical Industry Co., Ltd., particle size 1.2).
A conductive support for comparison was prepared in the same manner as in Example 1 except that the thickness was changed to μm).

Comparative Example 6 A comparative example was prepared in the same manner as in Example 7, except that Al (OH) ₃ in the conductive layer coating material of Example 7 was replaced with calcium carbonate (Softon 1200, manufactured by Bihoku Powder Chemical Industry Co., Ltd.). A conductive support was produced.

With respect to the conductive supports prepared in Examples 1 to 9 and Comparative Examples 1 to 6, each of the environmental conditions (20 ° C.
0% RH, 22 ° C 60% RH, 25 ° C 70% RH)
After leaving for 4 hours, use a ring resistor (Kawaguchi Denki Seisakusho, P
601 and an applied voltage of 100 V). The whiteness was measured according to JISP8123. Further, calendering was performed on the conductive supports prepared in Examples 1 to 9 and Comparative Examples 1 to 6 under a pressure of 100 kg,
The smoothness of the surface of the conductive layer on which the recording layer is coated is determined by JISP
Measured according to 8119. The measurement results are as follows.

[0034]

[Table 1]

On the conductive layer on one side of the conductive support,
A recording layer coating having the following composition was applied and dried to provide a recording layer having a coating amount of 5 g / m ² , thereby producing an electrostatic recording medium of the present invention or a comparative example.・ N-butyl methacrylate / methyl methacrylate (1: 1) copolymer molecular weight: about 100,000, 40% toluene solution 100 parts ・ calcium carbonate 40 parts ・ toluene 180 parts For the electrostatic recording medium prepared above, follow the procedure below. Image evaluation. Using an electrostatic color plotter (CE3436, manufactured by Versatech), each environmental condition (20 ° C.
An image is formed on an electrostatic recording medium at 0% RH, 22 ° C. 60% RH, 25 ° C. 70% RH), and image density is used as a recording characteristic (a black portion is measured using a Macbeth reflection densitometer RD-914). And the image was evaluated. In addition, the image quality evaluation was evaluated as も の when there was no image quality defect such as solid image uniformity and horizontal dropout, and Δ when at least one of the image quality defects was slightly recognized but had no practical problem. At least one of which was recognized as a practical problem to some extent was evaluated as x. Table 2 shows the results.

[0036]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the conductive support and the electrostatic recording medium of the present invention have a small change in the surface resistance value over a wide range of environmental conditions and have good recording characteristics. As a result, it was confirmed that the ink had excellent humidity resistance stability and good whiteness that could be sufficiently applied to color recording. On the other hand, Comparative Examples 1 and 3 were unsuitable for color recording due to low whiteness because no metal hydroxide was used, and also had poor recording characteristics. In Comparative Example 2, since the metal hydroxide was used in a large amount of 400 parts by weight with respect to 100 parts by weight of the acicular conductive pigment, the surface resistance was 2 to 6 × at a humidity of 60% RH or 70% RH. It was as high as 10 ⁹ Ω / □, and the recording characteristics also had a problem. Further, Comparative Examples 4 to 6 had a problem in recording characteristics because general pigments such as carbonates and oxides were used instead of metal hydroxides.

[0038]

As described above, the conductive support of the present invention and the electrostatic recording medium using the same are prepared by mixing a conventional needle-like conductive pigment with a metal hydroxide in the conductive layer to obtain a conductive moisture-resistant material. While obtaining excellent recording characteristics without impairing stability,
It has the effect of having excellent whiteness that can be applied to color recording.

Claims (4)

[Claims] 1. A conductive layer containing an acicular conductive pigment and a metal hydroxide is provided on at least one surface of a substrate, and the metal hydroxide is contained with respect to 100 parts by weight of the acicular conductive pigment. 5 to 300 parts by weight of a conductive support. 2. The needle-like conductive pigment has a major axis of 1 to 40 μm.
The conductive support according to claim 1, wherein the support is m-shaped and has a short axis of 0.05 to 3 m. 3. The metal hydroxide has a general formula M (OH) n
(N represents an integer of 2 to 4), M is an alkaline earth metal, aluminum, titanium or zinc, and the average particle diameter is 0.05 to 3 μm. 3. The conductive support according to 2. 4. An electrostatic recording medium, wherein a recording layer is formed on the conductive layer of the conductive support according to claim 1.