JPS6328452B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to preventing static electricity on plastic films, and more particularly to a method for producing antistatic plastic films. In general, plastic film is electrically insulating, and when it comes into contact with or peels off from materials of the same or different types during various handling operations, it becomes electrostatically charged and may attract dust or cause electric shock to workers. They often cause serious damage by causing a discharge or causing a discharge. Particularly when plastic film is used as a support for photographic materials, this charging phenomenon is an extremely serious problem. The best way to eliminate these problems caused by static electricity is to increase the electrical conductivity of the plastic film surface so that the static charges leak out in a short period of time. Therefore, in order to prevent static electricity on plastic films, it is well known that inorganic salts are coated with hygroscopic substances to form a conductive layer, or surfactants or polymer electrolytes are coated alone or together with a binder to form a conductive layer. There is. These methods are described in detail in, for example, Marumo: Antistatic Agents (Saiwai Shobo). However, in the method of applying these ionic compounds to prevent static electricity, the antistatic performance is dependent on humidity. That is, the conductivity of the coating layer decreases as the humidity decreases, resulting in the disadvantage that it no longer exhibits the desired antistatic performance. On the other hand, for example, U.S. Patent No. 3062700,
-113224 and JP-A-55-12927, etc.
Crystalline metal oxides such as zinc oxide, stannic oxide, and indium oxide, whose conductivity is almost independent of humidity, are used as conductive materials for conductive supports of electrophotographic photoreceptors or electrostatic recording materials. things are stated. Furthermore, Japanese Patent Application No. 55-47663 describes that conductive crystalline metal oxide fine particles are dispersed in a binder to form an antistatic layer in a photosensitive photographic material. These metal oxides are excellent conductive materials, but when these conductive metal oxide fine particles are mixed with a binder to form a conductive coating layer, the conductive fine particles are not present in this coating film. They need to come into contact with each other to create a continuous phase. In order to create a continuous phase, it is necessary to add more than a certain amount of conductive particles to the binder and apply more than a certain amount. However, if the coating amount is too large, coloring due to metal oxide fine particles or haze due to scattering of light by the particles may occur, which may impair transparency and may be unfavorable in terms of quality. There is also an increase in cost due to an increase in the amount of coating. SUMMARY OF THE INVENTION Accordingly, the first object of the present invention is to provide a method for producing an antistatic plastic film. The second object is to provide a method for producing a plastic film that has excellent antistatic properties even in low humidity conditions. The third object is to provide a method for producing an antistatic plastic film with little coloring and haze. A fourth object of the present invention is to provide a method for producing a plastic film that is antistatic. Fifth, it is an object of the present invention to provide an inexpensive plastic film that has excellent antistatic properties even in low humidity conditions and exhibits less coloring and haze. These objects of the invention include Zn, Ti, Sn, In,
At least one layer containing conductive fine particles mainly composed of an oxide of at least one metal selected from Si, Mo, and W and/or one or more metal composite oxides composed of oxides of these metals. In a manufacturing method for forming a layer on a plastic film,
(1) After dissolving the conductive fine particles, the organic solvent-soluble polymer, and the polymer and forming a film of a liquid containing at least two types of organic solvents with different boiling points, the organic solvent is removed to form a conductive film. or (2) forming a film of a liquid containing the conductive fine particles, an organic solvent-soluble polymer, and an organic solvent that dissolves the polymer, and then removing the organic solvent to form a conductive film; Before, at the same time, or after formation, an organic solvent-soluble polymer and the polymer are dissolved, and a film of a liquid containing an organic solvent having a boiling point different from that of the organic solvent used for the conductive film is formed, and then the organic solvent is removed. Provide a membrane (1)
Alternatively, the present invention has been achieved by a method for producing an antistatic plastic film, which is characterized in that an orange skin is generated in the layer containing the conductive fine particles by either method (2). Preferred conductive particles used in the present invention are crystalline metal oxide particles, including those containing oxygen defects and those containing a small amount of foreign atoms that form donors for the metal oxide used. Generally speaking, it is preferable because it has high conductivity. Examples of metal oxides include ZnO, _TiO2 ,
SnO ₂ , WO ₃ , In ₂ O ₃ , SiO ₂ , MoO ₃ and their composite oxides are good, especially ZnO, TiO ₂ and
_SnO2 is preferred. Examples containing different atoms include Al for ZnO,
In etc., Nb, Ta etc. for TiO ₂ , Sb, Nb, halogen atoms etc. for SnO ₂ . The amount of foreign atoms added is preferably in the range of 0.01 to 30 mol%, particularly preferably 0.1 to 10 mol%. The size of the conductive metal oxide fine particles in the present invention is preferably small in order to minimize light scattering. For example, it is preferably 0.01 to 5.0 μm, particularly 0.1 to 0.5 μm. The conductive fine particles made of crystalline metal oxide used in the present invention are mainly produced by the following method. Firstly, metal oxide fine particles are produced by firing and then heat treated in the presence of different atoms to improve conductivity.Secondly, metal oxide fine particles are produced by firing with different atoms to improve conductivity. Thirdly, when manufacturing metal particles by firing, the oxygen concentration in the atmosphere is lowered to introduce oxygen defects. For more details, reference may be made to the description in Japanese Patent Application No. 1983-47663. The volume resistivity of the conductive metal oxide fine particles in the present invention is preferably 10 ⁷ Ω-cm or less, particularly 10 ⁵ Ω-cm or less. In addition, the coating amount is 0.05 to 1 square meter.
It is preferably 10.0g, especially 0.1 to 5g. The conductive metal oxide fine particles of the present invention are dispersed in a binder and applied onto a plastic film. The binder that can be used may be any film-forming organic solvent-soluble polymer, such as cellulose derivatives such as acetylcellulose, acetylpropylcellulose, acetylbutylcellulose, acetylphthalylcellulose, ethylcellulose, methylcellulose, nitrocellulose, vinyl chloride, Vinylidene chloride, alkyl (carbon water 1 to 4 in the alkyl group) acrylate, methylalkyl (carbon water 1 to 4 in the alkyl group) acrylate, vinyl acetate, maleic anhydride, acrylic acid, styrene, vinylpyrrolidone, acrylamide, acrylonitrile, etc. Examples include homopolymers or copolymers thereof, soluble polyesters, soluble nylons, and the like. Examples of organic solvents (hereinafter referred to as "solvents") used to dissolve such binders include alcohols such as methanol, ethanol, and propanol, methylene chloride, chloroform, ethylene dichloride, and trichloride. Examples include chlorinated hydrocarbons such as ethylene, ketones such as acetone and methyl ethyl ketone, hydrocarbons such as cyclohexane, benzene, heptane, and octane, esters such as methyl acetate, ethyl acetate, and ethyl formate, and tetrahydrofuran. I can do it. Examples of relatively high boiling point solvents include cyclohexanone, methyl isobutyl, ketone, methyl cellosolve, ethyl cellosolve, ethyl lactate, methyl cellosolve acetate, ethyl cellosolve acetate, toluene, xylene, and ethane tetrachloride. A feature of the present invention is that when a layer containing conductive metal oxide fine particles is provided on a plastic film, an orange skin pattern is formed on the layer. Yuzu skin pattern is Vortex Cell or Venerd
Cell, but it is described in detail in, for example, Yuji Ozaki: Coating Engineering (Asakura Shobo) and Translated by Ueki et al.: Paint Flow and Pigment Dispersion (Kyoritsu Shuppan). When forming a layer containing conductive metal oxide fine particles, the yuzu skin pattern generates a large number of convection nuclei during drying.
This can be caused by the development of annular swirls, and this phenomenon depends on the solvent composition of the coating solution and the drying conditions. For example, in the case of single-layer coating, this can be achieved by having two or more solvents with different evaporation rates in the coating solution, and in the case of multi-layer coating, the upper layer can be removed before the lower layer is completely dry. It can be produced by applying it. The degree of this citron skin pattern can be appropriately controlled by selecting the combination of solvents in the mixed solvent system and by selecting the combination of solvents in the coating solution of each coating layer. By creating a citron skin pattern in a layer containing conductive metal oxide fine particles, the electrical resistance value of the layer can be reduced even if the amount of the fine particles applied is small compared to a case without such a yuzu skin pattern. . Examples of the plastic film used in the present invention include films of cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, polystyrene, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyvinyl chloride, polyethylene, polypropylene, nylon, and the like. I can list them. A conductive metal oxide is mixed with a binder and a solvent and applied onto these supports. In the case of single-layer coating, two or more solvents with different boiling points are used, and in the case of multi-layer coating, the lower and upper layers are used. uses solvents with different boiling points. The coating method is not particularly limited and includes, for example, dip coating, roller coating, bar coating, gravure coating, air knife coating, extrusion coating, and the like. This conductive plastic film can be used as a photographic support, an electrophotographic support, a packaging film, a matte film support, and the like. When the antistatic plastic film of the present invention is used as a support for photographic materials,
For example, a layer containing conductive metal oxide fine particles is provided on one side of a polyethylene terephthalate film, and a layer containing a photosensitive silver halide emulsion is further applied on the layer.
An intermediate layer or a protective layer may be provided, or a photographic layer such as a photosensitive silver halide emulsion layer may be provided on the surface opposite to the conductive layer via an undercoat layer. Various additives constituting these photographic layers, such as silver halide grains, chemical sensitizers, antifoggants,
There are no particular restrictions on hydrophilic colloid binders, hardeners, color couplers, ultraviolet absorbers, surfactants, matting agents, etc.
You can refer to the description in Vol. 176, pages 21-29 (December 1978). The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto. Example 1 Stannic chloride 65 parts by weight Antimony chloride 10 Ethanol 1000 A 0.5N aqueous sodium hydroxide solution was added to the solution having the above composition to adjust the pH to 3 to form a colloidal precipitate. The colloidal precipitate was separated by centrifugation and then washed with water to remove excess ions. Colloidal precipitate 100 with excess ions removed
Parts by weight were mixed with 1000 parts by weight of water and sprayed into a firing furnace heated to 700°C to obtain conductive powder. The average particle size of the powder was 0.25μ. Coating solutions A and B were prepared using the above powder. A liquid above powder 50 parts by weight Styrene-maleic anhydride copolymer 10 Methanol 200 Acetone 180 Ethyl cellosolve 120 B Liquid above powder 50 parts by weight Styrene-maleic anhydride copolymer 10 Ethyl cellosolve 500 One side 100 μ A solution with the following composition was applied to a polyethylene terephthalate film at a rate of ^10c.c./m2 .
It was dried at 130°C for 10 minutes. Cellulose acetate 1 part by weight Polyester (isophthalic acid and ethylene glycol and triethylene glycol copolymer)
0.2 parts by weight Methylene dichloride 100 〃 Methanol 30 〃 〃 Ethylene dichloride 70 〃 m-cresol 20 〃 On top of this cellulose acetate and polyester mixed solution, apply the above solutions A and B in varying amounts as shown in Table 1. Apply at 130℃ for 10 minutes.
I dried it for a minute and made a sample. A citron skin pattern was observed in those using coating liquid A, but no citron skin pattern was observed in those using coating liquid B. Each sample prepared in this way was heated at 25℃ and 10%RH.
After being left for 2 hours under these conditions, the surface electrical resistance of the coating film was measured using an insulation resistance meter (Model VE-30, manufactured by Kawaguchi Electric Co., Ltd.), and the results shown in Table 1 were obtained. As is clear from Table 1, the resistance value is lower in the sample in which the citron skin pattern has been formed at a lower coating amount.

[Table] Example 2 Zinc oxide 100 parts by weight Al(NO ₃ ) 10% aqueous solution of ₂ ·9H ₂ O 5 Water 100 The above mixture was irradiated with ultrasonic waves for 20 minutes to obtain a uniform dispersion. After drying this dispersion at 110°C for 1 hour,
It was fired for 5 minutes at ×10 ⁻⁴ Torr and 600° C. to obtain conductive zinc oxide having a volume resistivity of 2×10 ² Ω-cm. The average particle size was 2μ. These particles were ground in a ball mill to obtain particles with an average particle size of 0.7μ. Using this conductive zinc oxide, two types of liquids C and D were prepared. C Liquid Conductive zinc oxide 7.5 parts by weight 15 parts by weight Cellulose diacetate
2 〃 2 〃 Acetone 100 〃 100 〃 Ethyl cellosolve 50 〃 50 〃 D Liquid Conductive zinc oxide 7.5 parts by weight 15 parts by weight Cellulose diacetate
2 〃 2 〃 Ethyl Cellosolve 170 〃 170 〃 Each of the above solutions was coated on a cellulose triacetate support having a thickness of 120μ so that the dry coating thickness was 0.8μ. Yuzu skin developed on the surface where liquid C was applied, but D
No citrus skin was observed on the surface to which the liquid was applied. Surface resistivity of each sample at 25℃, 25%
The results of measurement at RH were as follows, and although liquid C had a smaller amount of conductive zinc oxide applied, the surface resistivity showed a smaller value.

【table】

Claims (1)

[Claims] 1 Mainly consisting of an oxide of at least one metal selected from Zn, Ti, Sn, In, Si, Mo, and W and/or one or more metal composite oxides composed of oxides of these metals. In a manufacturing method in which at least one layer containing conductive fine particles is provided on a plastic film, (1) the conductive fine particles,
or (2) forming a conductive film by dissolving an organic solvent-soluble polymer and the polymer and forming a film of a liquid containing at least two organic solvents with different boiling points, and then removing the organic solvent; After forming a film of a liquid containing fine particles, an organic solvent-soluble polymer, and an organic solvent that dissolves the polymer, the organic solvent is removed to form a conductive film, and an organic solvent is added before, at the same time, or after forming the conductive film. (1) or providing a film by dissolving a solvent-soluble polymer and the polymer, forming a film of a liquid containing an organic solvent having a boiling point different from that of the organic solvent used for the conductive film, and then removing the organic solvent; A method for producing an antistatic plastic film, characterized in that an orange skin is generated in the layer containing the conductive fine particles by any of the methods described in (2).