JPS59121342A - Electrophotographic recording electrically conductive paper base - Google Patents

Abstract

PURPOSE:To render conductivity uniform and stable, to improve photographic characteristics and to obtain a superior image by forming a conductive coating layer on the paper base of an electrophotographic recording layer made of TiO2 as an essensital photosensitive agent and a metal vapor-deposited layer on this coating layer. CONSTITUTION:A conductive coating layer and a metal vapor-deposited layer are formed on a paper base to obtain a conductive paper base. A photosensitive layer made of TiO2 as an essential photosensitive agent is formed on the paper base. Said coating layer has <=10<11> ohm surface resistivity a conductivity imparting material such as carbon black or polymer electrolyte is used and a water-soluble polymer or a hardenable resin is used as a principal component to improve solvent resistance. On this coating layer a metal vapor-deposited layer of aluminum or the like is formed. On the reverse side of the paper base another coating layer having <=10<11> ohm.cm volume resistivity is formed to improve conductivity in the thickness direction of the paper base, facilitate grounding, and prevent curling, etc. Such a paper base has uniform and stable conductivity and good compatibility with the TiO2 type photosensitive material, and an image free from image uneveness and good in gradation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a conductive base paper used for electrophotographic recording of the electro7ax system, which is provided with a photosensitive layer as a main ingredient, and more specifically, a conductive base paper in which a conductive coat layer is provided on a paper support. By applying metal vapor deposition on top of it, it has extremely uniform and stable conductivity, and has improved conductivity that gives good electrophotographic properties and brings out excellent image quality compared to titanium dioxide-based photosensitizers. Regarding the base paper.

The electrofax method of electrophotography, which has been put into practical use up until now, involves forming a photosensitive layer containing lead oxide as the main photosensitive material on conductive-treated paper (0# electronic base paper), and directly forming an image on the photosensitive layer. However, in the vicinity of acids, research has begun on titanium dioxide-based photosensitizers instead of lead oxide, and their excellent properties are attracting attention. In other words, titanium dioxide has a high dielectric constant and a large amount of charge retention even if the photosensitive layer is thin.
It has excellent properties such as the ability to easily obtain continuous gradation and the ability to obtain good smoothness when combined with a resin binder. In combination with liquid toner,
It has high resolution and excellent gradation reproducibility, and is characterized by the ability to produce detailed and clear images comparable to silver halide photography.
New developments are expected especially for color electrophotography.

However, the titanium dioxide-based photosensitizer has a narrow range of side selection with respect to the substrate, and although it exhibits the above-mentioned good properties with respect to gold, vanes (foils), metal-deposited films, etc., it does not work well with paper-based materials. When used with ordinary conductive base paper, good images cannot be obtained due to severe image unevenness and insufficient photosensitivity, and for this reason, it has not yet been put into practical use.

In other words, conventional conductive base paper uses polyvinyl alcohol (PV
It is obtained by coating or impregnating a treatment agent mixed with hydrophilic polymers such as A) (hydrophobic polymer emulsions such as inders and polyvinyl acetate, pigments such as clay, etc.); Conductive processing agents have problems such as insufficient absolute value of conductivity, insufficient uniformity of conductivity, inhibiting electrophotographic properties, and insufficient solvent resistance. On the other hand, it was completely unsuitable for titanium dioxide-based photosensitizers, which are extremely sensitive.

One way to solve the problems of conventional conductive base paper is to perform metal foil lamination or metal vapor deposition without using a paint-based conductive treatment agent. However, in reality, there are various problems that make it difficult to put it into practical use. In other words, in the case of metal foil laminate,
The metal foil is laminated to the paper support via an adhesive layer,
The conductivity of the metal surface is very good and uniform, but the adhesive layer becomes an electrical insulating layer, resulting in insufficient conductivity in the volume direction, and the back ground required for the electrofax method is insufficient, making it impossible to obtain satisfactory images. There was a problem that it was rare.

Another disadvantage of metal foil laminates is that they tend to undergo plastic deformation, and once the recording paper is bent, it cannot return to its original shape.

On the other hand, in the case of metal vapor deposition, there is no problem of plastic deformation, so it is rather preferable, but there are still many problems that remain to be solved. In other words, it is technically difficult to deposit all the layers directly on the paper due to the water content, and 1 (3) Usually, a pre-coat is applied to improve adhesion, and the process is carried out in a vacuum to prevent the generation of gas from the surface. However, in this case, (a) the precoat layer is insulating and has low conductivity in the volume direction (between the front and back of the paper), and the nose surface is incompletely grounded, causing the base paper to become charged. It is said that an electrostatic latent image corresponding to the original image cannot be formed, and (b) when the photosensitive agent is applied, a part of the pre-coat layer is dissolved and foamed due to the solvent, which prevents uniform coating of the photosensitive agent. This disadvantage of base paper is that when titanium dioxide is used as the main photosensitive material in the electrofax method, it has a greater effect on the quality of the recorded image than when using zinc oxide, and it is difficult to solve this problem. It has been demanded.

The present invention relates to solving the above problems. That is, the first aspect of the present invention is a conductive base paper for electrophotographic recording using titanium dioxide as a photosensitive main ingredient, which is characterized by having a paper support pressure conductive coating layer and a metal vapor deposition layer thereon, The second invention has a conductive coating layer on the paper support and a metal vapor deposited layer thereon, and a conductive corner K on the opposite side (back side) of the surface on which the metal vapor deposited layer of the paper support is provided. No. 1 is a conductive base paper for photographic recording, which has titanium dioxide as a photosensitive main agent and has a volume resistivity of 10110α or less. The conductive base paper of the present invention has good conductivity in the volume direction of the base paper and excellent solvent resistance. This material has good compatibility with the photosensitizer in the electrofax system using titanium dioxide as the main photosensitive agent, and is the most suitable for reproducing images with no image unevenness and good continuous gradation. Furthermore, in the second invention, the conductivity in the volume direction of the base paper is even better, and it is easier to ground the back surface. Therefore, a special device is added or a non-photosensitive layer is provided for grounding the surface. Special processing such as can be omitted. Further, it is possible to prevent the base paper from curling, and the drawing operation can be further stabilized. The conductive base paper of the present invention having the above-mentioned features is particularly desirable when producing color images by an electrofax method using titanium dioxide as a photosensitive main agent, as shown in Examples below.

In the present invention, the surface resistance of the conductive coating layer is 10110
It is desirable that the temperature is below (20℃ relative humidity 60℃),
In particular, it is desirable that the resistance be 1010Ω or more. If the surface resistance value is larger than the above range, the conductivity in the volume direction of the base paper will be inhibited, making it difficult to obtain the desired effect. Also, the volume specific t(
The resistance is preferably 1011 Ωm or less (20° C., relative humidity 60%), particularly preferably 10 IθΩ or less. If the body resistivity is larger than the above-mentioned range, it may be difficult to completely ground the back surface, and the image quality may not be reproduced. Further, in the present invention, it is necessary to use a material with particularly excellent solvent resistance for the conductive coating layer so as to prevent foaming during application of the photosensitive agent. That is, the following two methods can be employed to construct the conductive coat layer.

(The main components are a conductivity-imparting substance and a water-soluble polymer binder.)

(2) The main components are a conductivity-imparting substance and a curable resin binder.

(This method is characterized by mainly using water-soluble polymers to impart solvent resistance. For example, methyl cellulose, hydroxyethyl cellulose,
Cellulose derivatives such as carboxymethylcellulose, starch derivatives such as esterified starch, oxidized starch, and cationic starch, natural animal and vegetable resins such as sodium alginate, casein, gelatin, glue, gum arabic, and mannan, (meth)acrylates, Synthetic polymers such as polymers and copolymers such as maleate, polyvinyl alcohol, partially saponified polyvinyl acetate, polyacrylamide, polyvinyl methyl ether, polyvinylpyrrolidone, polyethyleneimine, polyethylene oxide, amine resins, and water-soluble polyethylene, etc. is used. These can be used singly or in combination. If necessary, polymer emulsions such as acrylic esters, methacrylic esters, acrylonitrile, styrene, vinyl acetate, vinyl chloride, vinylitine chloride, ethylene, propylene, butadiene, isoprene, glolobrene, etc. It is also possible to add a cross-linking agent such as amino resin, glyoxal, epoxidized polyamide, polyamine, zirconium complex salt, dialdehyde starch, etc. Furthermore, if necessary to improve smoothness or coatability, clay, kaolin, bentonite, talc, montmorillonite, silicic acid, aluminum silicate, magnesium silicate, alumina, zinc oxide, titanium oxide, calcium carbonate, magnesium carbonate, metal, etc. Inorganic pigments such as soap, magnesium oxide, magnesium hydroxide, calcium hydroxide, barium sulfate, zeolite, diatomaceous earth, satin white, etc., and organic pigments such as urea-formalin resin, polystyrene powder, starch powder, etc. can be added to the solvent resistant solvent. This is possible within a range that does not reduce performance.

On the other hand, method (2) is characterized by imparting solvent resistance using a curable resin, such as alkyd resin, reactive acrylic resin, phenolic resin, urea/melamine resin, unsaturated resin, etc. Polyester resins, polyurethane resins, polyamide resins, crosslinkable vinyl monomers, etc. are used. These hats need to be subjected to treatments such as adding a catalyst, heating, UV irradiation, and electron beam irradiation to suit each curing mechanism. Furthermore, if necessary, a pigment such as clay may be added.

Next, the conductivity-imparting substances commonly used in (2) are: ■Inorganic salts: hydrochlorides, nitrates, sulfates, carbonates, phosphates, etc.・Glycerin, ethylene glycol, tulpitol, cyanated Δψ powder, etc. ■Polymer electrolyte cationic property: A polymer compound having a quaternary ammonium base, a sulfonium base, or a phosphonium base in the main chain or in the Vi or 91J chain.

Example, polyvinylbenzyltrimethylammonium chloride Order 0 Anionic: A polymer compound having a carboxylic acid group, a sulfonic acid group, or a phosphonate group in its side chain.

For example, polystyrene sulfonic acid Sodium polyacrylate etc.

Amphoteric: A polymer compound that shares a cationic and anionic functional group.

■Metal fine powder - Au, Ag, Cu, A4 Ni,
Fe, Sn, Zn, etc. (recarbon black...powder, carbon FI1.
The surface of a metal oxide such as ZnO is doped with In, Cd, etc.

o, ZnO, etc., heat treated in COt, SOt, NHa gas.

C, solid solution such as 5n01.5b02, T(
To the reduced form of Ot, TIO, treated with 5n02.5b02, copper tatsude, silver iodide, etc. are used singly or in combination.

However, the conductivity-imparting substances listed in ■, ■, and ■ have the disadvantage that they tend to eat away at buttons and metal-deposited films because they draw in moisture and impart conductivity. Can not. This situation differs depending on the conductivity-imparting substance used, but usually the solid content of IN is 3.
It is 0% or less.

Ichiriki, ■, ■, ■ conductivity imparting substance is water and Vi+'!
Because it has a 7.% conductive mechanism without a 7% conductivity, there is no negative effect on corrosion, and especially the conductivity-imparting substances of
It is preferable to use a metal chloride for 1. In the present invention, the conduit conductive coating layer on the back side of the paper support can be formed by coating the above-mentioned conductive coating composition on the back side of the paper support, but it is also possible to form a metal vapor deposition layer on the layer. It's okay.

Impregnation of the paper support with the conductivity-imparting substance and mixing of the conductive substance can be carried out by conventional processing means. Examples of methods for forming the conductive coating layer include EVA coating, Meyer bar coating, roll coating, air knife coating, gravure coach ink, Flead coating, spray coating, size press, and impregnation. If further smoothness is required, t, t, super calender, machine calender, etc. may be applied.

The paper used as the support is not particularly limited, and may be either 9# paper or processed paper, and may be pre-mixed or impregnated with a tetraelectricity imparting substance.

You can use anything you like.

Next is the metal vapor deposition method, which is also not particularly limited.
It is possible to achieve the objective using any method ranging from ordinary vacuum evaporation and sputtering to ion blating.

The metals to be evaporated include gold, silver, copper, aluminum, rejected lead,
Any material such as lacquer or cadmium may be used, but aluminum is most commonly used.

It is sufficient for the vapor deposited film J to have a thickness of 11n of 50 mμ or more, and a thickness of about 5,50m7z to 100 mμ is more suitable.

In order to create ML recording paper for electrophotography having a photosensitive layer containing titanium dioxide as a main ingredient using the conductive base paper according to the present invention described in @, a coating liquid in which titanium dioxide is dispersed in a resin binder is used. This can be done by coating a conductive base paper INK.

As the titanium dioxide, titanium dioxide produced by various methods can be used, but titanium dioxide having rutile type crystals is more preferable. For example, oxidation +11' is added to the titanium dioxide mentioned in @.
Small amounts of other photoconductive materials such as u-lead can also be mixed in. Further, it is desirable to use various resin binders having high electrical insulation properties. For example, one or more of acrylic resins, alkyd resins, polyester resins, polyurethane resins, amino resins, vinyl resins, etc. can be used.

The present invention will be explained in more detail with reference to Examples below.
Of course, the present invention is not limited to this.

Example 1 A conductive coating agent (25% aqueous solution) was coated on high-quality paper (
Bj, 4ri/i) was dried with a Meyer bar, then coated so as to be the back side of 5, dried at 120°C for 10 minutes, and then coated with a back coating agent (20% aqueous dispersion) consisting of After drying with a Maygiver, it was coated to give a coating density of 103'/l♂, dried at 100°C for 10 minutes, and then coated with: -$ = ξ
5' tar treatment was applied. Surface resistance of conductive coating layer 14
It was 38×10100 at 20° C. and 60° relative humidity.

This was further dried at 100°C for 10 minutes, placed in a vacuum evaporation device, and subjected to aluminum evaporation under a vacuum of 10-'Torr.A shiny aluminum-deposited conductive base paper with a evaporation thickness of about 60 mμ was obtained. was gotten. The volume resistivity value of the conductive base paper is 1j at 20℃, 60℃ relative humidity, 62×
It was 1010 Ωm.

Next, titanium tetrachloride is hydrolyzed to precipitate hydrated titanium oxide, and this precipitate is filtered, washed, and dried, and then pulverized. to obtain titanium dioxide powder, which is mixed with the following sensitizing dye, etc.
The solvent was evaporated by heating to obtain titanium dioxide powder on which the solvent was adsorbed.

100 parts of the obtained titanium dioxide powder and Acridic A
-405 (acrylic resin manufactured by Dainippon Ink & Chemicals) 5
A photosensitizer coating solution was obtained by photographing 0 parts of toluene and 80 parts of toluene in a quick mill for 5 minutes.

The obtained photosensitive agent coating liquid was applied onto the conductive base paper for 15 minutes after drying.
It was coated with Meyer bar to a thickness of μ and dried at 100° C. for 10 minutes to obtain electrophotographic recording paper. This was heated to 20°C and 60°C.
After being left in the dark at %RH for 2 days, various tests were conducted.

(Electrophotographic properties) The electrophotographic properties of the obtained sample were measured using a paper analyzer SP~428 manufactured by Yoro Denki. It is expressed as the number of seconds it takes to reach the target.

(Image quality) Obtained. The sample was subjected to the following five steps to obtain a color electrophotographic image.

(1) Charging - Heavy color separation exposure - Yellow toner (2) Charging - Green separation exposure - Magenta toner (3) Charging - Red separation exposure - Antoner The image quality of this was visually evaluated using a five-level relative evaluation method (7). There are two evaluation items: uniformity (unevenness, defects) and overall characteristics (sharpness, Ft tone reproducibility).As shown in Table 1, the charging characteristics are excellent, and color electrophotography is also excellent. Extremely uniform and clear images were obtained, exhibiting precise and excellent gradation reproducibility similar to silver halide photography.

Thereafter, conductive base papers of Examples 2 to 7 were prepared in the same manner as in Example 1 except that only the conductive coat was changed, and the base paper, back coat, super calender, and aluminum vapor deposition were the same as in Example 1.

Example 2 After drying, a conductive coating agent (18% aqueous solution) consisting of the following was applied to one side of the pressing paper to give a coating density of 12 P/n.
It was dried for 10 minutes at 0°C to form a conductive base paper.

Example 3 was dispersed in an attritor to prepare a conductive coating agent (30% aqueous dispersion), and after drying under pressure on one side of the base paper, 10y/lt? The conductive base paper was coated with an air knife and dried at 100° C. for 5 minutes.

Example 4 was dispersed in a homomixer to prepare a conductive coating agent (35% aqueous dispersion), which was blade coated on one side of the base paper to a coating density of 131/nl after drying, and dried at 110°C for 10 minutes. It was made into a conductive base paper.

Example 5' was dispersed in a homomixer to prepare a conductive coating agent (35% aqueous dispersion), and after drying one side of the base paper, it was heated to 16 F/? 7/, perform Meyer bar coating and heat at 150℃-20
It was dried for a minute to form a conductive base paper.

Example 6 was dispersed in the attritor to create a conductive coating agent (30% toluene dispersion), and after drying it was coated on one side of base paper at 8 y/lt.
? It was gravure coated so as to have the following properties and dried at 150°C for 20 minutes to obtain a conductive base paper.

Example 7 was dispersed in a sand grinder (the catalyst was added later) to prepare a conductive coating agent (50% methyl ethyl ketone dispersion). It was dried for 15 minutes at -15°C to obtain a conductive base paper.

Table 1 shows the surface resistance values of the conductive coat layers obtained in Examples 2 to 7 and the volume resistivity values of the aluminum-deposited conductive base papers. 1011Ω or less, and the volume resistivity of the conductive base paper is 1
j10? It was within the range of ~1011Ω·σ.

Next, the obtained conductive base paper was coated with a titanium dioxide-based photosensitive agent in the same manner as in Example 1, and an electrophotographic recording paper was obtained and various tests were conducted. As shown in Table 1, the charging characteristics were There were no problems at all, and color electrophotographic images were also extremely uniform and clear, showing fine and excellent gradation reproducibility similar to silver halide photography.

Comparative Examples 1 to 7 The aluminum of Comparative Examples 1 to 7 was prepared in exactly the same manner as in Examples 1 to 7, except that the conductive coating agent from which the conductivity imparting substance was removed was used as the precoating agent. A vapor-deposited conductive base paper was prepared and coated with the same titanium dioxide-based photosensitizer as in Example 1 to obtain an electrophotographic recording paper, and various tests were conducted.

As a result, as shown in Table 1, the surface resistance of the precoat layer was all 1011Ω or more, and the conductive layer was coated with aluminum vapor deposition and a low resistance layer (back coat) was provided on the back surface. The volume resistance value of the base paper was inhibited by the high resistance coating layer, and only a high resistance value of 1011 to 10J4Ω could be achieved. Therefore, regarding the charging characteristics of the electrophotographic recording paper using this, the base paper was charged, and no image was obtained in electrophotography.

Comparative Example 8 In Example 2, only the conductive coat and back coat were applied. The volume resistivity of the super calender-treated base paper was 4.7 x 10100. A titanium dioxide-based photosensitive agent similar to that in Example 1 was directly coated onto the conductive coat without metal vapor deposition to obtain electrophotographic recording paper, and various tests were conducted.

As a result, as shown in Table 1, the charging characteristics were drastically reduced to 4.5 seconds, the rise of charging was very slow, and the color electrophotographic image had fine d^light unevenness over the entire surface. It was very uneven and unclear.

Table 1

Claims (1)

[Scope of Claims] 1) A conductive base paper for electrophotographic recording containing titanium dioxide as a photosensitive main ingredient, characterized by having a conductive coating layer on a paper support and a metal vapor deposited layer thereon. 2) The conductive base paper according to claim @rtnp41, wherein the conductive coating layer has a surface resistance of 10 11 Ω or less F. 3) The conductive base paper according to claim 1, wherein the main components of the conductive coating layer are (a) a conductivity-imparting substance, (b) a water-soluble polymer binder, or a curable Ita-1 fat. 4) The electrically conductive base paper according to claim 3, comprising a material selected from the group consisting of a material imparting toughness, carbon black, a conductive gold oxide, and a conductive metal halide. 5) It has a Ki'flt coating layer on a paper support and a metal vapor deposition layer thereon, and the paper support has a conductive coating layer on the surface opposite to the surface on which the metal vapor deposition layer is provided. , Kameko photographic recording i4'+li base paper containing titanium dioxide as a photosensitive main ingredient, characterized in that the volume resistivity is 10''Ω (7) or less. 6) The surface resistance of the conductive coating layer is 1011Ω. The conductive base paper according to claim 5 below.