JPS62270337A - Transparent conductive plastic film - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a transparent plastic film having electrical conductivity. More specifically, the present invention relates to a transparent conductive plastic film that has excellent scratch resistance and is easy to manufacture.

(Prior art) Conventionally, gold-N thin films such as gold, platinum, silver, palladium, and aluminum have been formed on transparent polymer films, and semiconductor thin films such as indium oxide, tin oxide, cadmium oxide, and steel iodide have been formed on transparent polymer films. The formed transparent conductive plastic films are known, and these are used for transparent electrodes for displays, transparent heating elements, electrostatic shield transparent windows, light selective transmission films, and the like. These are usually vacuum evaporation methods, CV
It is manufactured by vapor deposition methods such as the D method, ion blasting method, or sputtering method, but the equipment used in these methods is complicated and expensive, and it is difficult to manufacture general-purpose transparent conductive films that are used in large quantities. In addition to being unsuitable for manufacturing purposes, the energy absorbed by metal free electrons is generally close to the visible light range, resulting in poor transparency and poor adhesion between the transparent conductive film and the polymer film. There were disadvantages in that the transparent conductive film peeled off during various steps of manufacturing transparent electrodes, and the durability during use was insufficient. Among these drawbacks, various improvements have been made especially regarding adhesion (for example, Japanese Patent Application Laid-Open No. 1312-1312).
No. 38, No. 60-131711, Special Publication No. 60-390
No. 90), however, durability such as abrasion resistance is not sufficient.

On the other hand, surfactants (e.g., Japanese Patent Publication No. 60-44149), carbon blanks (e.g., Japanese Patent Publication No. 60-214945), and other conductive powders (e.g., Japanese Patent Publication No. 61-240) can be applied onto transparent films by coating. However, when a surfactant is used, the conductivity is affected by humidity, and the conductivity may be lost due to washing with clean water, which makes the conductivity insufficient especially in low humidity. be exposed. In order to prevent these drawbacks, if a surfactant is kneaded into the film, there is a drawback that the surfactant will accumulate on the surface over time, and if a carbon blank or the like is used, It had the disadvantage of insufficient transparency.

(Problems to be Solved by the Invention) As a result of careful consideration to solve these conventional drawbacks, the present inventors have developed a conductive layer consisting of an ultrafine metal oxide, a swelling agent for the support, and a suitable binder. When applied on a plastic film and further provided with a certain layer on top, the transparency easily reaches 80% or more, the adhesion to the plastic film support and scratch resistance are good, and the film is humidity-dependent. The present invention was achieved by discovering that it is possible to obtain a conductive plastic film free of .

Therefore, a first object of the present invention is to provide a conductive plastic film with good transparency and scratch resistance.

A second object of the present invention is to provide a conductive plastic film that is not dependent on humidity and has excellent transparency and scratch resistance.

A third object of the present invention is to provide a method for producing a conductive plastic film whose conductivity can be easily adjusted, has excellent scratch resistance, is not humidity dependent, and has a transparency of 80% or more. There is a particular thing.

(Means for Solving the Problems) The above aspects of the present invention are such that ZnO1Ti02, A
j! 203.1n203.5i02, MgO1B a
At least one crystalline metal oxide and/or at least one of these crystalline composite oxides with a particle diameter of 0.5 μm or less selected from Oz, Sn○2, and MoO3, a binder, and conductive layer and melamine resin,
A layer consisting of at least one polymer selected from phenolic resin, acrylic resin, urethane resin, polyacetal, polyarylate, polyimide, polyolefin, alkyd resin, polyester, epoxy resin, or derivatives thereof is provided. This was achieved using a conductive plastic film.

Examples of the transparent plastic film support used in the present invention include cellulose triacetate, cellulose acetate butylene, cellulose acetate propionate, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyethylene, polypropylene, etc., and laminates thereof. Although materials can be used, polyethylene terephthalate, polycarbonate and polyethylene are particularly preferred.

The support may be colorless or colored, and may be surface-treated to improve adhesion to the conductive film. Furthermore, it may contain an ultraviolet absorber or a heat ray cutting agent.

Examples of the crystalline metal oxide used in the present invention include:
ZnO1Tt02, Sn○21.11:03, Tn20
3.5i02, MgO1B20. MoO2 and composite oxides thereof can be mentioned, but among these, ZnO5T i O2 and s n, o 2 are particularly preferred, and as composite oxides, Aj2, in
etc., N b for TiO2, , Ta etc., Sn○2
sb, Nb, halogen elements, etc.
Those containing 01 to 3Qmol% are preferable, especially 0.1
Preferably, it contains ~10 mo1%. In addition, the volume resistivity of these conductive fine particles is 107Ω・cm or less, especially 10
It is preferable that it is 5Ω·cm or less. It is preferable that the crystal has oxygen defects or contains a small amount of a foreign atom that serves as a so-called donor for the metal oxide, since the conductivity is improved.

Such conductive fine particles can be manufactured as follows. That is, the first method is a method in which metal oxide fine particles are produced by firing and then heat-treated in the presence of foreign atoms that improve conductivity, and the second method is a method in which metal oxide fine particles are produced by firing. The third method is to reduce the oxygen concentration in the atmosphere and introduce oxygen defects when producing metal fine particles by firing. These methods can also be combined as appropriate.

Details of these are described in, for example, Japanese Patent Application Laid-Open No. 143430/1983.

Binders for the conductive layer used in the present invention include proteins such as gelatin, derivative gelatin, colloidal albumin, and casein; cellulose compounds such as carboxymethyl cellulose, hydroxyethyl cellulose, diacetyl cellulose, and triacetyl cellulose; agar, sodium alginate, and starch derivatives. sugar derivatives such as; synthetic hydrophilic colloids such as polyvinyl alcohol, poly-N-vinylpyrrolidone, polyacrylic acid copolymers, polyacrylamide or derivatives thereof, and partial hydrolysates, polyvinyl acetate, polyacrylonitrile, polyacrylic acid Vinyl polymers such as esters and copolymers thereof, natural products such as rosin and shellac and derivatives thereof, and many other synthetic resins are used. Also, styrene-butadiene copolymer,
Emulsions of polyacrylic acid, polyacrylic esters and derivatives thereof, polyvinyl acetate, vinyl acetate-acrylic ester copolymers, polyolefins, olefin-vinyl acetate copolymers, etc. can also be used. Others include carbonate, polyester, urethane,
Organic semiconductors such as epoxy resins, polyvinyl chloride, polyvinylidene chloride, and polypyrrole can also be used. These binders can also be used in a mixture of 2 ft or more.

Among these binders, polyacrylic acid copolymer,
Preferred are polyacrylamides, polyacrylonitrile, polyacrylic esters, polycarbonates, polyesters, polyvinyl chloride and polyvinylidene chloride.

In order to increase the transmittance of the transparent conductive plastic film as a whole, it is natural that it is preferable that the plastic film as a support, the crystalline metal oxide, and the binder each have high transparency. The main components of the conductive layer are a crystalline metal oxide and a binder, so in order to prevent the metal oxide and the binder from having a large difference in refractive index and causing increased light scattering, the refractive index of both must be adjusted to the same level. It is preferable to do so.

This adjustment can be easily made by adjusting the particle size of the metal oxide.

The refractive index of the binder used in the present invention is approximately 1°4-1
．． 6, the diameter of the conductive particles is preferably 0.5μ or less, and in particular, by using conductive particles with a diameter of 0.2μ or less, the light scattering efficiency can be made 10% or less. Also, considering the manufacturing conditions, it is preferable that the thickness is 0.01μ or more.

A more detailed explanation of the production of fine conductive particles can be found, for example, in JP-A-56-14.3430.

In the present invention, in order to improve the adhesion between the conductive layer and the support, it is preferable that the conductive layer contains a compound that swells the support.

Examples of the compound that swells the support used in the present invention include resorcin, chlorresorcin, methylresorcin, 0-cresol, m-cresol, p-cresol, phenol, 0-chlorophenol, p-chlorophenol, and dichlorophenol. Chlorphenol, trichlorophenol, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid,
Trifluoroacetic acid, chloral hydrate, etc. can be mentioned, and resorcinol and p-chlorophenol are particularly preferred.

Since these swelling agents swell the surface of the support when the conductive layer is applied, they can increase the adhesive force between the support and the conductive layer. Since the swelling agent remains even after the conductive layer is dried, the adhesive strength does not deteriorate due to washing with water or over time, and therefore, the durability of the transparent conductive plastic film of the present invention is extremely good.

The resistance of the conductive layer in the present invention can be adjusted to 101Ω·C11l to 101Ω by adjusting the volume content of conductive particles in the conductive layer and/or by adjusting the thickness of the conductive layer.
It can be easily adjusted to the 0Ω range. However, in order to have sufficient strength as a conductive layer,
Preferably, the amount of binder is not less than 5% by weight. The proportion of conductive fine particles is 30% to 90% by volume,
More preferably, it is 50% to 80%, and the amount used is 0.
゜05g/rd ~5. Og/n (, preferably 0.1
g/d to 2.0 g/rJ.

The compound that swells the support is 0.01 g/m to 5.0 g/m.
g/rrr, preferably 0.05 g/n? ~1゜0g
/cd.

When applying the conductive layer, a dispersion of the above composition is prepared by appropriately selecting a solvent. Selection of the solvent can be easily made by those skilled in the art. There are no particular restrictions on the coating method, and any method can be selected from known methods. Further, during coating, known coating aids such as saponin and dodecylbenzenesulfonic acid, hardening agents, coloring agents, ultraviolet absorbers, heat ray cutting agents, etc. can be added to the coating liquid as appropriate and necessary. Further, in order to improve the adhesion between the support and the conductive layer, a subbing layer may be provided between the two.

Transparent conductive plastic films are easily damaged not only during the manufacturing process, but also during use because they are often used in areas that are easily touched by hands. The dominance-resistant layer provided in the present invention can protect the conductive layer from such disadvantages.

The scratch-resistant layer of the present invention may contain one or more appropriately selected from melamine resin, phenol resin, acrylic resin, urethane resin, alkyd resin, epoxy resin, polyacetal, polyarylate, polyimide, polyester, polytrefin, or derivatives thereof. Although two or more types can be used in combination, acrylonitrile and polymethyl methacrylate are particularly preferred among these. In addition, from the viewpoint of adhesion with the conductive layer, it is preferable to select a resin that is the same as or compatible with the binder used for the conductive layer, and it is preferable to select a resin that is the same or compatible with the binder used for the conductive layer. It is preferable to select a material having substantially the same refractive index as that of the conductive layer from the viewpoint of reducing the amount of refraction and ensuring transparency. The thickness of the scratch-resistant layer is preferably 0.01 to 10μ, particularly preferably 0.1 to 3μ.

The conductive plastic film of the present invention has a conductivity of 109
〜IQloΩ・佽, it can be used as an antistatic sheet for glass, walls, etc. Also, conductivity is 1
When the resistance is 05 to 106 Ω, it can be used as an electrostatic recording material or touch panel, and when it is 102 to 103 Ω, it can be used as an electromagnetic barrier.

(Effects of the Invention) Since the conductive blast film of the present invention uses ultrafine metal oxide as conductive particles, it can easily achieve transparency of 80% or more. Furthermore, since the swelling agent of the support remains in the conductive layer, not only is the adhesion between the conductive layer and the support good, but also the conductive layer is covered with a scratch-resistant layer, resulting in excellent durability. Furthermore, since a coating method is used, which is cheaper than a vapor deposition method, the product cost can be reduced, making it an excellent general-purpose conductive plastic film.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 [Preparation of tin oxide-antimony oxide composite dispersion] 230 parts by weight of stannic chloride hydrate and 23 parts by weight of antimony trichloride were dissolved in 300 parts by weight of ethanol to obtain a homogeneous solution.

An aqueous solution of IN sodium hydroxide was added dropwise to this solution until the pH of the solution became 3 to obtain a coprecipitate of colloidal stannic oxide and antimony oxide. The obtained coprecipitate was
C. for 24 hours to obtain a reddish-brown colloidal precipitate.

A reddish-brown colloidal precipitate was separated by centrifugation. In order to remove excess ions, water was added to the precipitate and the precipitate was washed with water by centrifugation. This masterpiece was repeated three times to remove excess ions.

200 parts by weight of the colloidal precipitate from which excess ions have been removed are redispersed in 1500 parts by weight of water and sprayed into a calcining furnace heated to 600°C to form a bluish tin oxide-antimony oxide composite with an average particle size of 0.2μ. A fine powder was obtained. The specific resistance of this fine particle powder was 25 Ω・cm. A mixed solution of 40 parts by weight of the above fine particle powder and 60 parts by weight of water was
After adjusting to H7.0 and coarsely dispersing it with a stirrer, use a horizontal sand mill (trade name: DYNO MILL: WILLYA, BACHOF).
(manufactured by EN AG) until the residence time reached 30 minutes.

[Preparation of sample] Gelatin - 0.3 parts by weight water
-・3.6 parts by weight acetic acid
-・0.3 parts by weight methanol -85,
8 parts by weight p-chlorophenol - 10.0 parts by weight The undercoat liquid (A) having the above composition was applied to a 10 μm polyethylene terephthalate film to a dry film thickness of 0.1 μm and heated at 130”C for 30 seconds. The following antistatic coating liquid (B) was applied on top of this to a dry film thickness of 0.
It was applied to a thickness of 1 μm and dried at 130° C. for 2 minutes.

[Antistatic coating liquid (B) Conductive fine particle coating liquid 10 parts by weight Gelatin 1 part by weight Water
27 parts by weight methanol
60 parts by weight p-chlorophenol 2 parts by weight polyoxyethylene nonylphenyl ether 0.01 part by weight Furthermore, a coating liquid (C) for coating layer having the following composition was applied so that the dry film thickness was 0.1μ. Sample 1 was prepared by drying at ℃ for 2 minutes.

[Coating liquid for coating layer (C) Copolymethyl methacrylate 1 part by weight Acetone 70 parts by weight Methanol
15 parts by weight dichloromethylene
10 parts by weight p-chlorophenol
4 parts by weight Next, Comparative Sample 1 was prepared in the same manner as Sample 1 except that the coating layer was removed.

Furthermore, for comparison, Comparative Sample 2 was prepared in the same manner as Sample 1 except that the conductive fine particle dispersion liquid (B) was removed.

Sample 1, Comparative Samples 1 and 2 were obtained as described above, and the surface resistance, haze, adhesion between the antistatic layer and the support, and scratch resistance were measured. The test method used was the method described below.

[Measurement of surface resistance] The surface resistance of the support coated with the coating layer was measured in an atmosphere of 25° C. and 10% RH using an insulation resistance meter VE-30 (Kawaguchi Electric ■i).
! This was done using

[Measurement of Haze Degree] Each sample after coating the antistatic layer and the coating layer was measured using an integrating sphere type haze meter (Model 5EP-H-3 manufactured by Nippon Seimitsu Kogaku). Good results are marked as ○, cases where there is no practical problem but poor results are marked as △, and cases where there are practical problems are marked as ×.

[Method for evaluating the adhesion between the antistatic layer and the support] Fix the sample with the bank side facing upward, and place it on paper for 3k.
It rubs at a constant speed with a load of g. The amount of material adhering to the paper due to friction and the strength of peeling of the bank surface were measured with the naked eye.

If the condition is good, it is indicated by ○, and if there is a problem in practical use, it is indicated by ×.

[Scratch resistance measurement]

The occurrence of scratches was observed by increasing the load continuously.

0110~ for cases where there is no damage even when a load of 15g is applied
The case where the weight was 14g was evaluated as △, and the case where scratches occurred at 10g or less was evaluated as ×.

Table 1 shows the results of testing using the above method.

Table 1゜Sample details 1 Comparative sample 1 Comparative sample 2 Haze ○ △ ○ Scratch resistance
○ △ 0 As is clear from Table 1,
Sample 1, which is the invention of the present application, has excellent adhesion between the film support and the antistatic layer, and does not generate static marks. Comparative sample 1 has a haze inferior to sample 1, but there is no problem in practical use. However, in Comparative Sample 2, which does not contain conductive fine particles, the surface resistance of the support is high and static marks occur.

Claims (1)

[Claims] ZnO, TiO_2, Al_2O_3, In_2 on at least one side of the transparent plastic film support.
O_3, SiO_2, MgO, BaO, SnO_2, M
At least one crystalline metal oxide with a particle diameter of 0.5 μm or less selected from oO_3 and/or at least one of these crystalline composite oxides, a binder and a conductive layer, and a melamine resin and a phenol resin. , acrylic resin, urethane resin, polyacetal, polyarylate, polyimide, polyolefin, alkyd resin, polyester, epoxy resin, or a derivative thereof. Transparent conductive plastic film.