JP3155766B2 - White composite sheet with improved whiteness and light fastness for electrostatic image display capable of reproduction display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white composite sheet for electrostatic image display which can be reproduced and displayed by a direct charging system.
Since the composite sheet according to the present invention has high whiteness, little change in color tone due to light, and excellent light resistance, a stable image with high contrast can be obtained, and the display surface of a large display using an electrostatic image can be obtained. When used as such, an excellent effect is exhibited.

[0002]

2. Description of the Related Art A direct charging type electrostatic recording material is usually composed of a dielectric layer for holding static electricity and a semiconductor layer having a function as an electrode. Generally, an electrostatic image is formed on the surface by applying the voltage, and is visualized using toner or the like.

As a material which has been put into practical use, a base paper coated with a conductive material such as a quaternary ammonium salt type resin is used as a semiconductor layer, and on the surface thereof, acrylic styrene, methacryl styrene, polyvinyl chloride / vinyl acetate copolymer is used. There is known an electrostatic recording paper formed by applying a resin dielectric layer made of a derivative resin such as a silicon resin, an alkyd resin, or an epoxy resin, and an inorganic substance such as barium sulfate, titanium oxide, calcium carbonate, and kaolinite. However, materials having a configuration such as that seen in this electrostatic recording paper are not suitable for reproduction display because the change in conductivity due to humidity, the durability of the surface dielectric layer, or the erasability of the information once recorded is poor and cannot be displayed. A composite sheet as the object of the present invention cannot be obtained.

The present inventor has recently developed a semiconductor film having a surface resistance of 10 ³ to 10 ¹⁰ Ω / □ containing a fibrous or flake-like conductive filler and a high dielectric substance having a relative dielectric constant of 5 or more. It has been found that a reproducible electrostatic image display sheet can be obtained by laminating a film with the film, and based on such a finding, the invention of the "reproducible electrostatic image display or recording composite sheet" was first made. (Japanese Unexamined Patent Publication No. 2-25605
6).

[0005] Compared with conventional materials, such an electrostatic image display sheet is excellent in moisture resistance and durability, has no change in resistance value even when mechanical tension is applied, and has a large screen sheet industrially. Are also advantageously obtained, and are suitable for electrostatic recording applications such as large facsimile machines and large copiers.

[0006] However, the conductive filler used here, for example, carbon fiber, stainless steel fiber, aluminum fiber, etc., has good conductivity. When the composite sheet is used as a display surface of an electrostatic image, the contrast between a recorded portion and an unrecorded portion in visualization with toner decreases, and it becomes difficult to obtain a sufficiently clear image. Problems arise. In the above invention, fibrous titanium dioxide and alkali metal titanate fibers coated with tin oxide and antimony oxide, which have recently been developed (Japanese Patent Application Laid-Open No. 57-10324, 59-6235, 59-414, etc.)
It has also been proposed to use fibrous fillers having relatively high whiteness, such as conductive fibers produced by the method described in Japanese Patent Publication No. 25-259. Further, in the above invention (Japanese Patent Application Laid-Open No. 2-256056), a method using a white fibrous and / or flaky conductive filler covered with a complex oxide composed of tin and cobalt as a conductive substance of a white semiconductor layer. Although such fillers have been proposed, the use of such a filler has not yet sufficiently satisfied the contradictory properties of conductivity and whiteness of the composite sheet. Further, although the sheet using these fillers has been improved as compared with the conventional one, the problem regarding light resistance such that the whiteness decreases over time when exposed to light still remains. There is a need for the development of such composite sheets.

[0007]

Accordingly, an object of the present invention is to provide a composite sheet "reproducible electrostatic image display or recording composite sheet" previously invented by the inventor of the present invention (JP-A-2-25).
6056) improved whiteness and light resistance without the addition of special fillers, and economical use of large-screen display materials capable of reproducing and displaying clear contrast images even when used as display surfaces for large displays. It is also provided in an advantageous manner.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to provide a composite sheet having the above-mentioned disadvantages, and as a result, have found that a white composite semiconductor film comprising two layers, a high-resistance layer and a low-resistance layer, is provided. It has been found that by laminating a high dielectric film, a composite sheet having a stable conductivity in a semiconductor region and having improved whiteness and light resistance can be obtained. Was completed.

That is, the surface of the composite sheet of the present invention, which is basically composed of ^two layers: a high resistance layer having a surface resistance of 10 ⁷ to 10 ¹⁰ Ω / □ and a low resistance layer having a surface resistance of 10 ² Ω / □ or less, for example. resistance
A composite semiconductor film of 10 ⁴ to 10 ⁷ Ω / □ and a high-dielectric film having a dielectric constant of 5 or more are laminated on the high resistance layer side. A reinforcing layer such as resin or cloth is provided.

[0010] The white composite semiconductor film used in the composite sheet of the present invention maintains a stable resistance value even when mechanical tension is applied or changes in environment such as temperature and humidity. It is required to have such a characteristic that a change in color tone is small even when exposed to light. For this reason, paper-based ones such as conventional electrostatic recording paper cannot be used in terms of durability and moisture resistance, and film bases include polyethylene, polypropylene, polystyrene, vinyl acetate, vinyl chloride, Non-cellulosic synthetic polymers such as silicone resin, rubber, epoxy resin, polyurethane, acrylic resin, and polycarbonate are used alone or as a blend or a copolymer. Of these, non-yellowing type polyurethane or vinyl acetate coating resins are preferred because of ease of film processing and little discoloration due to light.

As a conductive filler for imparting conductivity to both high and low resistance layers of a composite semiconductor film using these base films to form a white semiconductor film, from the viewpoints of conductivity, whiteness and light resistance, The following are advantageously used: That is, the surface of a white or pseudo-white fibrous or scaly or plate-like substrate is covered with a composite oxide film of tin and antimony, and the ratio of tin to the total of tin and antimony in the composite oxide film is About 80-90% by weight, the ratio of antimony is about 10-20% by weight, and the total of tin and antimony in the conductive filler is about 10-30% by weight. White conductive excellent in whiteness and light resistance. About 0.05% in the metal composition of these composite oxides, if desired, for the purpose of improving the whiteness and light resistance.
Conductive fillers containing up to 1% by weight of cobalt.

The shape of the white or pseudo-white conductive filler used here is such that the fibrous filler has a needle-like ratio of 10 to 1000 and a major axis length of 0.05 μm to 1 mm.
In the case of a flaky or plate-like filler, those having a flake diameter of 10 μm to 5 mm, a thickness of 0.05 to 10 μm, and an aspect ratio of 10 to 1000 are preferred from the viewpoint of stability of conductivity.

Specific examples of the base material of the conductive filler are as follows. A scaly or plate-like substrate is also called a flake-like substrate, and mica is a typical example. Although there are many types of mica depending on the components contained, any of them can be used as a flake-like substrate, and among them, muscovite (muscovite) is particularly preferable. Sericite, talc, and the like can also be used as other flake-like base materials. Further, examples of artificial flake-like substrates include those obtained by coating mica with titanium oxide, glass flakes, and alumina flakes. On the other hand, as the fibrous base material, wollastonite, potassium titanate fiber, gypsum fiber, zonolite, MOS fiber (MgSO ₄ , 5MgO.8H ₂₎
O), PMF (Processed Mineral Fiber), glass fiber, ceramic fiber, rock wool fiber and the like. In addition to the above, any fibrous or flaky white material can be used as the base material of the conductive filler of the present invention.

The white conductive filler used in the present invention is, for example, a tin-antimony compound which is reacted with the above-mentioned base material by reacting tin chloride with an antimony compound and, if desired, a cobalt compound in an alkaline aqueous solution. By forming a coating film of the composite oxide, and then aging in an acidic solution, followed by dehydration and drying, followed by heat treatment at a high temperature.

The conductive filler thus obtained is indispensable for maintaining the color tone, film processability, and resistance to mechanical tension of the semiconductor film used in the present invention, and is used alone or in combination. However, when the desired whiteness is not sufficient just by filling the film base with the filler, in order to improve the whiteness, for example, titanium dioxide, zinc oxide, tin oxide, white inorganic substances such as antimony oxide. It is good to use together. By adding these white inorganic substances, the whiteness can be improved and the light fastness can be improved. Among these white pigments, titanium dioxide having a high hiding power is particularly preferred for the purpose of the present invention.

Although not desirable in terms of whiteness, metallized glass fibers such as stainless steel fiber, alumina fiber and coated glass fiber, and highly conductive fillers such as aluminum flakes, nickel flakes and nickel-coated mica may be used if necessary. Can be used to prepare the white semiconductor film of the present invention and adjust its conductivity and thus its resistance. Incidentally, these high conductive materials are preferably used for the low resistance layer which does not require more whiteness than the high resistance layer in the composite semiconductor film. Further, as the low resistance layer, a commercially available film on which a conductive metal such as aluminum or nickel is deposited or coated, or a metal foil such as a stainless steel foil can be used as it is.

The formation of the white high-resistance layer and the low-resistance layer using the above-mentioned non-cellulosic polymer and conductive material does not require a special method, and an ordinary resin processing method can be used. For example, when a thermoplastic resin is used for the film base, the conductive filler and the resin can be preliminarily mixed and then easily formed into a film by a calender method, a T-die method, or the like. In addition, a conductive filler and a white pigment are added to a resin solution using methyl ethyl ketone, toluene, dimethylformamide, etc., and the mixture is kneaded with three rolls or the like to prepare a paint, and the paint film is drawn with an applicator, gravure puller, etc. A method of drying and removing the solvent to form a film can also be used. On this occasion,
Within the range that does not affect the conductivity, it is not possible to exert its function by using what is usually added to resin, such as antioxidant, ultraviolet absorber, plasticizer, lubricant, surface treatment agent, coupling agent, etc. No problem.

When a white high-resistance layer and a low-resistance layer are formed using these materials, the amount of the conductive filler added to the film base is preferably such that the surface resistance of the high-resistance layer is 10 ⁷ to 10 ^{7. The} resistance is appropriately adjusted so that the surface resistance of the low-resistance layer is preferably 10 ² Ω / □ or less. When the surface resistance of the high resistance layer is smaller than the lower limit, the whiteness is reduced, and when the surface resistance is larger than the upper limit, the image forming ability is reduced.
On the other hand, when the surface resistance value of the low resistance layer is larger than the above upper limit, the image forming ability is similarly reduced.

When a composite semiconductor film is prepared using these materials, the whiteness of the composite semiconductor film generally increases as the thickness of the white high-resistance layer increases, but the conductivity decreases. Conversely, when the thickness of the white high-resistance layer decreases, the conductivity of the composite semiconductor film improves, but the color tone approaches that of the low-resistance layer, and the whiteness decreases. Therefore, in order to form a composite semiconductor film having a surface resistance of 10 ⁴ to 10 ⁷ Ω / □ using both of these resistance layers, not only the resistance values of the high resistance layer and the low resistance layer but also the white It is necessary to adjust the thickness of the high resistance layer by paying attention to the degree. By the way,
The reason for setting the surface resistance of the composite semiconductor of the present invention to 10 ⁴ to 10 ⁷ Ω / □ is that a ghost is liable to occur at the time of development at a lower resistance value, while a writing voltage is increased at a higher resistance value. This is because the electrical load on the device increases.

On the other hand, in the dielectric film used in the composite sheet of the present invention, if the dielectric constant is small, the capacitance of the composite sheet is reduced, and it is not possible to hold sufficient static electricity for attracting toner, and it is clear. It becomes impossible to obtain a proper image. In this case, with a resin having a small dielectric constant, the capacitance of the composite sheet can be increased by reducing the film thickness, but on the other hand, a new problem that dielectric breakdown easily occurs occurs. Therefore, a high dielectric film having a relative dielectric constant of 5 or more, preferably 7 or more is used as the dielectric film in the present invention. In addition, such a high-dielectric film must be suitable for reproduction and use, and various characteristics such as good erasability of the toner once adhered, low frictional resistance and high voltage resistance are required.

Those satisfying these characteristics include polyvinylidene fluoride, cyanoethylated polyol, polyvinylphosphabenzene, polyvinylquinoline, polyvinylpyrimidine, polyvinylpyridazine, polymethylpyridine, polydimethylpyridine and the like. These may be used alone, as a blend or as a copolymer, and if necessary, may be polyacrylate, methacrylstyrene, acrylicstyrene, vinyl chloride /
It may be used in combination with other resins such as vinyl acetate copolymer, silicone resin, alkyd resin, epoxy resin, and the whiteness and light resistance of the composite sheet within a range that does not impair the properties as a high dielectric film. And the like may be added to improve whiteness.

From the viewpoint of maintaining a large capacitance of the composite sheet, the film thickness of the dielectric film made of these resins is within a range that does not cause a decrease in the mechanical strength or abrasion resistance of the film or a dielectric breakdown. It is better to be as thin as possible,
A film having a thickness of 1 to 50 μm, preferably 5 to 30 μm is suitable for the purpose of the present invention.

The composite sheet of the present invention can be obtained by laminating the above-described composite white semiconductor film and the dielectric film. The laminating method is a method of laminating with an adhesive or using an adhesive. For example, a method of thermocompression bonding a composite white semiconductor film and a dielectric film is used, but a method using an adhesive is preferable in terms of mechanical strength of the composite sheet and ease of lamination.

Examples of the adhesive include dielectric films such as polyacrylate, polyacrylstyrene, acrylicstyrene, methacrylstyrene, alkyd resin, epoxy resin, vinyl chloride / vinyl acetate copolymer, silicon resin, and styrene-butadiene rubber. Those that do not impair the characteristics of are used. Each of these resins may be used alone, or as a blend or copolymer, or may be used in combination with another resin as necessary, or a white inorganic substance for improving the whiteness or light resistance of the composite sheet. Can be added in a range that does not impair the adhesive strength.

The thickness of these pressure-sensitive adhesives is 1 to 30 μm, preferably 3 to 20 μm. If the thickness is larger than this, the characteristics of the dielectric film are impaired, and the holding power of static electricity is reduced, so that a clear image cannot be obtained. On the other hand, if the thickness is smaller than this, air bubbles are apt to be mixed during lamination, which deteriorates the aesthetic appearance, causes image unevenness, and lowers the mechanical strength of the composite sheet.

[0026]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

In the examples and comparative examples, the measurement of surface resistance, the measurement of whiteness, and the evaluation of image forming ability were performed as follows.

(Measurement of Surface Resistance) The measurement was carried out using a surface resistance meter “Hiresta” and “Loresta” manufactured by Mitsubishi Yuka Corporation.

(Measurement of Whiteness) (Composite) A semiconductor film or a film surface of a high-resistance layer is placed on a glass surface of a digital colorimeter (UNICC-33H, manufactured by Toyo Seiki Seisaku-sho, Ltd.), and these whitenesses are measured. (L value) was measured. The whiteness (L value) of the high dielectric film surface of the composite sheet was measured in the same manner.

(Evaluation of Image Forming Ability) The evaluation was performed using the same apparatus as that shown in FIG. 11 of JP-A-2-256056. That is, a stainless steel rod having a diameter of 2 mm was used as a writing electrode V ₁ , 20 mm × 100
A stainless steel plate having a size of 2 mm × 2 mm is used as the control electrode V _2, and the distance between the electrodes is 10 mm, and the stainless steel plate is placed on the high dielectric film of the composite sheet. While maintaining the inter-electrode distance 10mm while applying a load of 50g to the write electrodes V _1, it is 100mm move across a composite sheet at a rate of 50 mm / sec. At this time, the write electrode V ₁
Is 250V, to the control electrode V ₂ by applying a voltage of 300V, the
A total voltage of 550 V is applied on the composite sheet. Immediately after the writing is completed, the toner (D232, manufactured by Fuji Xerox Co., Ltd.) is applied to the composite sheet with a brush, and an electrostatic latent image having a straight line of 100 mm is developed.

The image was evaluated as follows: when the 100 mm electrostatic latent image was developed clearly without interruption, ○: when there was no interruption, but when the density unevenness was 3% or less of the whole, When it was more than 3% and less than 5%, it was evaluated as Δ, and when the density unevenness was 5% or more or the line was interrupted without development, it was evaluated as x. In order to achieve the object of the present invention, evaluation of ○ or ● is required.

In the following examples,% and parts are% by weight and parts by weight, respectively.

Example 1 Polyurethane having a solid content of 30% (manufactured by DIC, Pendix)
T-5625L) 133 parts, coating metal composition: 86.8% tin, antimony
Conductive fibrous titanic acid composed of 12.9% and cobalt 0.3% (Otsuka Chemical Co., Ltd., needle ratio 30-100, major axis 10-20μ)
m) 10 parts and 50 parts of titanium dioxide (R-5N, manufactured by Sakai Chemical) were kneaded together with 60 parts of DMF to prepare a conductive paint. This paint was dried on an aluminum foil having a surface resistance of 10 ^-1 Ω · cm or less and applied so as to have a thickness of 40 µm to prepare a composite semiconductor film.

Under the aluminum foil of the composite semiconductor film, a reinforcing PET (diapet, 100 μm thick, manufactured by Mitsubishi Kasei)
m) using an adhesive, and a 25 μm polyvinylidene fluoride film (made by Kureha Chemical Co., Ltd., KF film P-) on the conductive paint using a polyacrylate adhesive.
20, and a dielectric constant of 10) to obtain a 6-layer composite sheet.

Example 2 Polyurethane having a solid content of 30% (manufactured by DIC, Pendix T-
5265L) 133 parts, coating metal composition 89.5% tin, antimony 10.
Conductive fibrous potassium titanate composed of 3% and 0.2% of cobalt (manufactured by Otsuka Chemical Co., Ltd., acicular 30-100, major axis 10-20μ)
m) 8 parts, conductive granular titanium dioxide (Mitsubishi Metal, W
1) 2 parts and 50 parts of titanium dioxide (R-5N, manufactured by Sakai Chemical) were kneaded together with 60 parts of DMF to prepare a conductive paint. This paint was dried on an aluminum foil having a surface resistance of 10 ^-1 Ω · cm or less and applied so as to have a thickness of 40 µm to prepare a composite semiconductor film.

Under the aluminum foil of the composite semiconductor film, a reinforcing PET (diapet, 100 μm thick, manufactured by Mitsubishi Kasei)
m) using an adhesive, and a 25 μm polyvinylidene fluoride film (made by Kureha Chemical Co., Ltd., KF film P-) on the conductive paint using a polyacrylate adhesive.
20, and a dielectric constant of 10) to obtain a 6-layer composite sheet.

Example 3 Polyurethane having a solid content of 30% (PC-14C manufactured by Hitachi Chemical Co., Ltd.)
L) 100 parts, coating metal composition of tin 87.8%, antimony 11.8
% And cobalt 0.4%, 10 parts of conductive muscovite (Otsuka Chemical Co., Ltd., flake diameter 40 μm, thickness 3 μm) and 45 parts of titanium dioxide (Sakai Chemical Co., R-5N) are kneaded with 60 parts of DMF to prepare a conductive paint. Prepared. Apply this paint to 10 ^-1 Ω
・ 40μ after drying on aluminum foil with surface resistance of less than cm
m to give a composite semiconductor film.

Under the aluminum foil of the composite semiconductor film, a reinforcing PET (diapet, 100 μm thick, manufactured by Mitsubishi Kasei)
m) using an adhesive, and a 25 μm polyvinylidene fluoride film (made by Kureha Chemical Co., Ltd., KF film P-) on the conductive paint using a polyacrylate adhesive.
20, and a dielectric constant of 10) to obtain a 6-layer composite sheet.

Example 4 (Preparation of high-resistance layer) 100 parts of polyurethane (PC-14CL, manufactured by Hitachi Chemical Co., Ltd.) having a solid content of 30%, a coating metal composition of 87.8% tin,
Conductive muscovite composed of 11.8% antimony and 0.4% cobalt (Otsuka Chemical, flake diameter 40μm, thickness 3μ)
m) 13 parts and 57 parts of titanium dioxide (R-5N, manufactured by Sakai Chemical) were kneaded together with 40 parts of DMF to prepare a conductive paint for a high resistance layer.

(Preparation of low-resistance layer) 100 parts of polyurethane having 30% solid content (manufactured by Seiko Chemical Co., Ltd., rack skin U-1285) and nickel-coated mica (manufactured by Mitsubishi Metal Industries, flake diameter: 30 to 40 μm, thickness: 0.1 to 0.3) μm, aspect ratio 50 ~
100) 70 parts were kneaded together with 40 parts of DMF to prepare a conductive paint for a low resistance layer.

(Preparation of Composite Sheet) A low-resistance paint is applied on a reinforcing PET (Diapet, 100 μm thick, manufactured by Mitsubishi Kasei), and a low-resistance layer having a thickness of 50 μm after drying is formed. Further, a high-resistance paint is applied thereon so as to have a thickness of 30 μm after drying to form a high-resistance layer.

A polyacrylate pressure-sensitive adhesive was applied to a thickness of 10 μm on the high-resistance layer, and a 25 μm-thick polyvinylidene fluoride film (KF-P-20, relative dielectric constant: 10 made by Kureha Chemical) was applied. A composite sheet composed of five layers was laminated.

Comparative Example 1 Instead of the composite semiconductor film, a semiconductor film having a thickness of 50 μm prepared by using the conductive paint of Example 1 was laminated with a reinforcing PET and a high dielectric film according to the method described in Example 1. A composite sheet composed of layers was prepared.

Comparative Example 2 Instead of the composite semiconductor film, a 50 μm thick semiconductor film prepared using the conductive paint of Example 2 was laminated with a reinforcing PET and a high dielectric film according to the method described in Example 2. A composite sheet composed of layers was prepared.

Comparative Example 3 Instead of the composite semiconductor film, a 50 μm thick semiconductor film prepared by using the conductive paint of Example 3 was laminated with a reinforcing PET and a high dielectric film according to the method described in Example 3. A composite sheet composed of layers was prepared.

COMPARATIVE EXAMPLE 4 The high-resistance layer paint of Example 4 was dried on the reinforcing PET and then dried.
It is applied to a thickness of μm to form a semiconductor film layer. On top of this, a polyacrylic ester-based pressure-sensitive adhesive
And a 25 μm-thick polyvinylidene fluoride film (KF-P-20, KF-P-20, relative dielectric constant: 10) was laminated to form a composite sheet composed of four layers.

Table 1 shows the characteristic values such as the image forming ability of the composite sheet in the examples, and Table 2 shows those in the comparative examples.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

According to the composite sheet of the present invention, since the semiconductor film has a two-layer structure of a high-resistance layer and a low-resistance layer, the white sheet of the sheet has been difficult with a conventional composite sheet using a single-layer semiconductor layer. It has become possible to balance the opposite properties of power and conductivity. This is the case of the composite sheet of the present invention,
This is because the appearance such as whiteness is maintained by the white high resistance layer, and the conductivity is carried by the low resistance layer having low whiteness. In fact, as shown in Tables 1 and 2, the composite semiconductor film in Example 3 had a lower surface resistance than the semiconductor film of Comparative Example 1 or Comparative Example 4 using the single-layered semiconductor film according to the invention, It shows good conductivity and high whiteness. Also,
When Example 1 and Comparative Example 1 are compared, they show almost the same whiteness, whereas the surface resistance value of Example 1 (the present invention) is three orders of magnitude lower than that of Example 1. It can be seen that is improved.

As a result, when the composite sheet of the present invention is used as a display surface of an electrostatic image, whiteness and light fastness are improved and a clear image with high contrast is obtained as compared with a composite sheet having a conventional configuration. Becomes possible.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiromi Tahara 1-1, Suzukicho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Ajinomoto Co., Inc. (72) Koichiro Kakinuma, Inventor Koichiro Kakinuma 6-7 Kitashinagawa, Shinagawa-ku, Tokyo 35 Inside Sony Corporation (72) Inventor Masato Ando 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Naoya Kato 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo In Sony Corporation (56) References JP-A-59-61836 (JP, A) JP-A-61-233747 (JP, A) JP-A-2-256056 (JP, A) JP-A 1-273063 ( JP, A) JP-A-2-277068 (JP, A) JP-A-63-47776 (JP, A) JP-A-63-60452 (JP, A) JP-A-57-22243 (JP, A) JP-A-63-31856 (JP, A) P, A) (58) investigated the field (Int.Cl. ^7, DB name) G03G 5/00 - 5/16

Claims (7)

(57) [Claims] 1. A Ri high resistance layer and name are stacked white composite semiconductor film and in its high-resistance layer side dielectric constant formed of two layers and five or more highly dielectric film of the low-resistance layer, a high resistance
Koso is ^{10 7} ~10 10 Ω / □, low-resistance layer is 10 ² Ω / □ or less
Surface resistance of the white composite semiconductor film.
A white composite sheet for electrostatic image display capable of reproducing and displaying excellent whiteness and light resistance, having a resistance of 10 ⁴ to 10 ⁷ Ω / □ . 2. A fibrous white conductive filler or a flake diameter of 10 μm to 5 mm, wherein the high resistance layer is made of a non-cellulosic polymer and has a needle ratio of 10 to 1000 and a major axis length of 0.05 μm to 1 mm.
2. The white composite sheet for electrostatic image display according to claim 1, which is excellent in whiteness and light fastness and capable of reproducing display, comprising a flake white conductive filler having a thickness of 0.05 to 10 [mu] m and an aspect ratio of 10 to 1000. 3. A low-resistance layer is made of a metallized film or a metal foil according to claim 1 or 2 white degree and white composite sheet for reproducing displayable electrostatic image display with excellent light fastness according to any one. 4. A fibrous conductive filler or a flake having a needle-like ratio of 10 to 1000, a major axis of 0.05 μm to 1 mm, and / or a flake diameter of 10 μm to 5 mm, wherein the low-resistance layer is made of a non-cellulosic polymer.
0.05 to 10 [mu] m, whiteness and light fastness with excellent reproduction displayable electrostatic image display white composite according to claim 1 or 2 comprising a flaky conductive filler having an aspect ratio of 10 to 1000 Sheet. 5. The white according to any one of compound semiconductor film and the relative dielectric constant of 5 or more dielectric film and formed by laminating through an adhesive layer having a thickness of 3~20μm claims 1-4 A white composite sheet for electrostatic image display that is excellent in brightness and light resistance and can be reproduced. 6. An adhesive layer comprising at least one of polyacrylate, polyacrylstyrene, acrylic styrene, methacrylstyrene, alkyd resin, epoxy resin, vinyl chloride / vinyl acetate copolymer, silicone resin, and styrene butadiene rubber. The white composite sheet for electrostatic image display according to claim 5 , which is excellent in whiteness and light fastness and capable of reproducing and displaying. 7. The dielectric film contains at least one of polyvinylidene fluoride, cyanoethylated polyol, polyvinyl phosphabenzene, polyvinyl quinoline, polyvinyl pyrimidine, polyvinyl pyridazine, polymethyl pyridine, and polydimethyl pyridine. The white composite sheet for electrostatic image display according to any one of claims 1 to 6 , which is excellent in whiteness and light resistance and can be reproduced and displayed.