JPH052711B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a transparent conductive film, and its purpose is to produce a transparent conductive film for use in liquid crystal display devices, electroluminescent display devices, conductors, resistive heating elements, selective light emitting devices, etc. The purpose is to industrially produce transparent conductive films using inks for transparent conductive films that are useful as absorbents or art supplies.

Vacuum deposition method, sputtering method, ion plating method, lamination method, etc. are known as methods for producing transparent conductive films (for example, Okaniwa, Functional Materials, Vol. 2, No. 10, 8).
Page, 1982 and Sugiyama, Surface, Volume 21, January issue,
36 pages, 1981). In addition, a transparent conductive film is formed by mixing a tin compound as a main ingredient with an indium compound or an antimony compound, making a paste using ethyl cellulose and butyl cellosolve, and depositing this paste on a glass substrate by screen printing and baking it. A method has also been published (see JP-A-57-212268).

The present inventors have so far conducted numerous studies on the production of transparent conductive films using various methods.
All of the above methods require fairly expensive equipment, and the workability is not good and the quality of the product is not stable in order to form a large-area transparent conductive film or a patterned conductive film on a heat-resistant substrate. However, it was difficult to say that it was an economically effective method. Furthermore, it was difficult to reproduce sufficient conductivity as expected by the screen printing method using a known paste. The inventors of the present invention have made earnest efforts to eliminate these drawbacks, and as a result, they have finally completed a remarkable invention.

In other words, the present inventors found that tin and indium each have a content of 10 to 1000% per mole of Group Group elements of the periodic table.
When a film is formed on a heat-resistant substrate using an ink for transparent conductive film whose active ingredient is an organic compound containing moles of each of these elements and then fired, it is extremely difficult to process it in an oxidizing atmosphere containing ozone. They discovered that it is possible to produce a transparent conductive film of excellent quality.

The present invention will be explained in detail below.

The group element of the periodic table is at least one element selected from the group consisting of arsenic, antimony, and bismuth, and these elements can be used alone or in a mixture of two or more. The organic compounds containing this are, using antimony as a representative example, alkylantimony,
aralkylantimony, alkenylantimony,
Aromatic antimony residues, saturated or unsaturated organic acid antimony salts, saturated or unsaturated organic acid antimony compounds, compounds in which some of the hydrogen atoms of stibane are replaced with organic compound groups, organic acid salts of stibane, antimony salts Alternatively, organic chelate compounds of antimonyl salts, alkoxyantimony, and antimony compounds having a structure in which some of the substituents of the above-mentioned antimony compounds are substituted with other organic atomic groups or halogen atoms, etc. Furthermore, arsenic compounds and bismuth compounds are similar to this antimony compound. The common features of these organic compounds of group elements of the periodic table are:
It has good solubility, compatibility, melting point depressing properties, and dispersibility with respect to the organotin compounds and organoindium compounds described below without using a special organic solvent, and a beautiful and uniform film can be easily formed. It must be something that is Moreover, when made into ink, it has good storage stability and has a structure that does not ignite, precipitate, gel, or cause unnecessary reactions during storage. The compounds must be selected for organotin compounds as well as organoindium compounds.

The organic tin compound referred to in the present invention is a saturated or unsaturated organic acid tin compound (organic acid compound including monobasic acid, dibasic acid, polybasic acid, and aromatic acid) or an organic chelate compound of a tin salt. In addition, in the case of organic acid tin compounds, it is sufficient that one or more organic acid groups are bonded to tin, and the remaining bonds of tin are hydroxyl groups, alkoxy groups, hydrocarbon groups, carbonyl groups,
It may be bonded to an oxygen atom, a halogen atom, etc.

In addition, the structure that the organic indium compound should have is the same as or similar to the above tin compound, but the organic tin compound and the organic indium compound do not have to be compounds with the same structure, and should be considered from the viewpoint of compatibility, melting point depressing property, etc. It is better that the compounds are formed differently from each other. However, in the case of polybasic acid salts, tin and indium may of course be mixed and bonded to one organic acid.

The abundance ratio of each element in the active ingredients of a number of inks for transparent conductive films containing an organic compound of Group Group of the Periodic Table, an organic tin compound, or an organic indium compound as an active ingredient is as follows in terms of molar ratio.

The amounts of tin and indium present are each 10 to 1000 mol, particularly preferably 50 to 500 mol, each per 1 mol of the group element of the periodic table. If the amounts of tin and indium are each less than 10 moles, the performance of the ink will be insufficient and printability will be poor. Furthermore, if the amounts of tin and indium are each 1000 moles or more, the effect of containing the elements of group group of the periodic table cannot be sufficiently exhibited, and no improvement in the conductivity of the conductive film of the product is observed. Organic compounds of Group Elements of the Periodic Table that are easy to use for industrial purposes include triphenylantimony, tritolylantimony, triphenylarsine, bismuth subsalicylate, bismuth subgallate, and bismuth octylate, and examples of organic tin compounds include trimenaltin. (meth)acrylate, triethyltin (meth)acrylate, tripropyltin (meth)acrylate, tributyltin (meth)acrylate, tin maleate, tin fumarate, tin itaconate, as well as future oligomers and polymers,
Alkoxytin maleate, alkoxytin succinate, alkoxytin malonate, tin octylate,
tin naphthenate, etc. Examples of organic indium compounds include indium acetate, indium (meth)acrylate, indium caproate, indium octylate, indium naphthenate, indium adipate, indium maleate, indium malonate, indium succinate, and indium salt acetylacetonate. be.

The above organic compounds of group V elements of the periodic table, organic tin compounds, and organic indium compounds are subjected to two or three preliminary tests, and if their mutual compatibility and mixing condition are good, they can be separated separately. It may be synthesized and blended, or after blending, heat homogenization treatment, that is, cooking, may be performed to cause a certain degree of reaction between the materials and stabilize the material. It is also possible to prepare an alloy or inorganic salt mixture or complex of indium and indium, and use these as raw materials to produce the desired organic compound.

If an ink for transparent conductive film is suitable as an ink, it is desirable that the content of each main element as an active ingredient is as high as possible, and it is desirable to use it as is, but since it is used as an ink, it is desirable that the content of each main element as an active ingredient is as high as possible. In order to exhibit functionality such as coating, printing, or adhesion, it may be necessary to add an appropriate amount of a binder or solvent to form an ink.

Further, heat-resistant substrates referred to in the present invention include glass, quartz glass, sapphire, spinel, lutile, silicon, alumina, zirconia, zirconia/alumina, mullite, various garnets, barium titanate, strontium titanate, potassium titanate, In addition to mica and asbestos, materials with good heat resistance such as various ceramics are useful, and from an economic standpoint, substrates such as glass, quartz glass, mica, alumina, mullite, and ceramics are excellent.

In addition, as a method for forming the film, methods such as dipping, spraying, spin coating, and printing, such as screen printing and transfer printing, using the above-mentioned ink for transparent conductive films, are used. As for the printing method, for example, see the thin film printing method already invented by the present applicant in Japanese Patent Application Laid-Open No. 181682/1982, Japanese Patent Publication No. 3-4395, Japanese Patent Publication No. 2-16227, and Japanese Patent Publication No. 2-16228. ), it is ensured that thin films of particularly uniform thickness can be easily formed.

To carry out the method of the present invention, after the above-mentioned ink film formation step is completed, the ink film is subjected to a step of hot air drying, ultraviolet irradiation, or other fixing operation, if necessary, to accelerate drying and hardening of the ink film. The heat-resistant substrate, on which a homogeneous ink film has been completed in this way, is then heated at 300°C to 600°C.
The transparent conductive film that is the object of the present invention is formed through this process. The heating and baking process at this time is a necessary step to oxidize and decompose and remove as much of the organic carbon content as possible in the ink film, and this is usually carried out in an oxidizing atmosphere. be. At this time, it is important to note that if the firing temperature is below 300℃, carbon content will remain on the substrate surface, and if the firing temperature is above 600℃, the residual carbon content may get mixed into the substrate or the substrate may become deformed. The firing temperature is 300 to 600℃ because there is a risk of stains or distortions on the board.
should be. Furthermore, in the present invention, the selection of the atmosphere among the above-mentioned firing conditions is also an important factor, and based on many experiments conducted by the present inventors, it has been found that the firing is carried out in an oxidizing atmosphere, such as in a high oxygen stream or It is guaranteed that a high-quality product will be obtained if the process is carried out in air containing a small amount of ozone, and the practical method is to flow air containing a considerable amount of ozone over the substrate at a particular time after firing. It has thus been found that the objective can be achieved relatively easily.

The present invention can be carried out through the process described above, and the transparent conductive film obtained by the present invention is mainly composed of indium oxide and tin oxide, which is doped with an appropriate amount of group element oxide. The beautifully made conductive film retains any desired shape, has extremely few defects due to cloudiness, speckles, and coloring, and has good electrical conductivity. By selecting appropriate material relations and operating conditions, the difficult problem of the occurrence of localized non-uniform spots within the membrane (which tends to occur with large areas) can also be overcome.

Representative examples are extracted from among the many experimental examples of the present inventors, and are shown below. However, the present invention should not be interpreted as being limited to the examples shown below, and the embodiments thereof may be arbitrarily modified. Of course, it can be changed.

Example 1 100 parts of indium octylate, 14 parts of tin octylate
parts, antimony octylate 0.5 parts, nonionic surfactant 1 part, 2-ethylhexyl alcohol 20 parts
Using a spinner, apply a solution of 100 parts of xylene to a glass substrate using a spinner.
It was applied for 20 seconds at 2000 rpm.

Next, this glass substrate was left in a hot air dryer at 200°C for 30 minutes, and then fired in an electric furnace at 500°C for 30 minutes. Immediately remove the glass plate from the electric furnace.
It was kept in an ozone stream for 10 minutes. The ozone concentration in the airflow at this time was 6.6 g/m ³ .

After performing the above treatment, the glass plate was cooled, taken out, and inspected. As a result, a transparent conductive film with a light transmittance of 91.3% and a surface resistance of 2.0 kΩ/□ was formed.

Example 2 100 parts of indium acetylacetonate, 50 parts of triptyltin methacrylate, 0.5 part of triphenylantimony, and nonionic surfactant 2
An ink was prepared by diluting the mixture consisting of 1/2 xylene/cyclohexane with a mixed solvent of 1/1 xylene/cyclohexane to give a viscosity of 200 cps.

Using this ink, the depth of the intaglio is 30μm,
The average opening diameter and opening area are 40 μm and 45
%, 60μm, 10.0%, 80μm, 17.5%, the recess volume per ^1cm3 is approximately ^0.1mm3 , approximately ^0.2mm3 , approximately 0.35mm3 ^, respectively.
Using an intaglio plate with three types of small holes in the necessary areas, the three types of small holes were filled with ink, and the surface was scraped off with a steel doctor blade to remove excess ink. A rubber-based photosensitive letterpress plate with convex parts, APR-K-50 (trade name) manufactured by Asahi Kasei Co., Ltd., was attached to the top of the convex part, and ink according to the volume was transferred from three types of small holes to the top of the convex part. The protrusions were pressed against the surface of a glass plate to be printed, and three types of ink coatings with different thicknesses were printed according to the designs of the protrusions.

After drying this glass plate at 200℃ for 30 minutes,
It was fired in an electric furnace at 500°C for 30 minutes, and immediately after firing, it was cooled by flowing an ozone stream for 10 minutes.The concentration of the ozone stream at this time was 11.7 g/m ³ air. After baking, cooling and inspection, the resulting transparent conductive films had film thicknesses of 700-800 Å and 900-800 Å, respectively.
1100Å, 1200~1500Å, and the transmittance is respectively
93.3%, 91.3%, and 88.7%, and the surface electrical resistances were found to be 3.0 kΩ/□, 2.2 kΩ/□, and 1.0 kΩ/□, respectively.

Example 3 200 parts of indium sorbate, 50 parts of diptyltin diacetate, 0.5 parts of bismuth subsalicylate, 25 parts of ethyl cellulose, 100 parts of ethyl acetoacetate,
and 100 parts of cyclohexanone was prepared.

Using this ink, a pattern was formed on a glass plate by silk screen printing at 150 lines/inch. The printed glass plate was then dried at 150°C for 30 minutes and subsequently fired in an electric furnace at 480°C for 30 minutes.
After firing for 30 minutes, an ozone stream was passed for 10 minutes. The ozone concentration at this time was 7.1 g/m ³ .
After slowly cooling the glass substrate to room temperature, it was taken out and inspected, and the light transmittance was 88.2%, and the surface resistance was 88.2%.
The resistance was 1.5 kΩ/□, and a beautiful transparent conductive film with the desired pattern was formed.

Claims (1)

[Scope of Claims] 1. Heat resistance is achieved by using an ink for a transparent conductive film containing an organic compound as an active ingredient containing tin and indium in an amount of 10 to 1000 moles each for each mole of a group element of the periodic table. 1. A method for producing a transparent conductive film, which comprises forming a film on a substrate, firing the film, and then treating the film in an oxidizing atmosphere containing ozone. 2. The method for producing a transparent conductive film according to claim 1, wherein the Group Group element of the periodic table is at least one element selected from the group consisting of arsenic, antimony, and bismuth.