JPH0622975B2 - Transparent conductive laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent conductive laminate, and more specifically, a transparent conductive material suitable for use as a transparent electrode of a transparent touch panel or an electrophotographic recording material. The present invention relates to a laminated body.

[Prior art]

BACKGROUND ART Conventionally, as a transparent conductive laminate, one in which an indium oxide-based transparent conductive layer is laminated on a substrate made of an organic polymer substance is well known.

This laminate has excellent transparency and conductivity, but the transparent conductive layer is a thin film, so the surface strength is weak and the abrasion resistance is poor, so the conductive layer is scratched. It was easy to cause defective products in various processing steps to make transparent electrodes.

Therefore, it has been proposed to provide an organic polymer material or an organic silicon compound as a protective film on the transparent conductive layer.

However, such an improved laminate still has the following drawbacks. That is, (1) the surface strength is weak when the protective film is an organic polymer,
It is impossible to completely prevent the generation of water in the conductive layer. On the other hand, in the case of the organosilicon compound, the surface strength is strong, but the surface adhesiveness is poor, so that there is a drawback in that the adhesion failure occurs in various processing steps for forming the transparent electrode.

[Problems to be solved by the invention]

The object of the present invention is to solve the above-mentioned drawbacks, to completely protect the transparent conductive layer, and to provide a transparent conductive laminate capable of completely preventing the trouble of adhesion failure in various processing steps.

[Means for solving problems]

The present invention has the following configuration to achieve the above object:
What is claimed is: 1. A transparent conductive laminate comprising a base material (A) made of an organic polymer, a transparent conductive layer (B) containing indium oxide as a main component, and a protective layer (C), which are laminated in this order. (C) is a three-dimensional copolymer obtained by copolymerizing a tetraalkyl titanate and a hydrolyzate of an organoalkoxysilane, and In the bond (M ₁ and M ₂ are Si or Ti), The transparent conductive laminated body is characterized in that the proportion of bonds is 15 to 70 mol%.

Examples of the base material (A) made of an organic polymer material that constitutes the laminate of the present invention include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and polyphenols. Examples include vinyl resins such as methylmethacrylate and polyvinyl chloride, and plastics such as polycarbonate.
The thickness is preferably 0.004 to 5 mm.

The base material made of the organic polymer in the present invention can be subjected to the following surface activation treatment, if necessary. That is, a physical method such as glow discharge, electron beam irradiation, flame treatment, corona discharge or the like, or a chemical removal method such as acid or alkali treatment is used.

It is also possible to coat a thin film of melamine resin, polyurethane resin, polyester resin or the like.

The transparent conductive layer of indium oxide used in the present invention as a main component (B) In ₂ O ₃ alone or In ₂ O ₃ on was contained SnO ₂ of about several% In ₂ O ₃ · SnO ₂ ( Indium Tin Ox
ide) or In ₂ O ₃ as the main component, and cadmium (C
Examples include transparent conductive layers to which impurities such as d) and antimony (Sb) have been added in small amounts.

As a method for forming an indium oxide-based thin film on an organic polymer material substrate, there are methods such as a vacuum deposition method and a sputtering method.

In the case of the vacuum deposition method, for example, In ₂ O containing several% SnO _{2
Using 3} as the evaporation source, 10 ^-4 to 10 ^-6 Torr in the vacuum chamber
With a degree of vacuum, a thin film can be formed on a substrate by resistance heating or an evaporation method using an electron beam.

In the case of the sputtering method, an In-Sn alloy containing several% of Sn is added in the presence of an argon / oxygen mixed gas at 10 ^-3 to 10 ^-4 Torr.
A thin film can be formed on a substrate by the reactive sputtering method with a degree of vacuum. The film thickness of the indium oxide-based transparent conductive layer can be arbitrarily selected depending on the relationship between the light transmittance and the electric resistance value. To obtain the light transmittance of 70% or more and the electric resistance value of 10 ⁵ Ω / □ or less, 30 to 1,000Å is suitable.

The protective layer (C) provided in the present invention comprises a three-dimensional copolymer obtained by copolymerizing a tetraalkyl titanate and a hydrolyzate of organoalkoxysilane, and (M ₁ and M ₂ are Si or Ti) in the bond It is necessary that the proportion of bonds is 15 to 70 mol%. Since this compound can be formed extremely strongly on the indium oxide-based transparent conductive film by the following method, it is extremely useful in various processing steps for producing a transparent electrode.

The cross-linked product having a bond can be formed by applying a dilute solution of a mixture of a hydrolyzate of alkoxysilane and tetraalkyl titanate and then cross-linking it by a thermosetting reaction or the like. in this case, Join, A bond is also formed, but It is important that 15-70 mol% of the compound containing the bond is formed.

In the present invention, The bond ratio can be determined from the peak position (O _1S ) of the chemical shift showing the bonded state of oxygen with an ESCA LAB-5 apparatus manufactured by Vacuum Generator.

The thickness of the protective layer (C) is preferably 30 Å or more and 3,000 Å or less. If the thickness of the protective layer is less than 30Å, the surface strength is insufficient, which is not preferable.
When it exceeds 3,000Å, the surface strength of the protective film is sufficient, but it hinders the surface electric characteristics of the transparent conductive layer.

〔The invention's effect〕

The following effects can be obtained by using the transparent conductive laminate of the present invention.

The surface strength and wear resistance of the transparent conductive layer are significantly improved.

Since the adhesiveness of the substrate (A) / transparent conductive layer (B) / protective layer (C) is improved, the problem that the transparent conductive layer is peeled from the substrate can be eliminated.

Adhesion between the protective layer (C) and the conductive paint for circuit formation is required in various processing steps for forming the transparent electrode, but since the adhesion with the conductive paint is improved, troubles of poor quality are completely eliminated. Can be resolved.

The characteristic values of the present invention are based on the following measuring methods.

(1) Visible light transmittance Using a haze meter (SEP-HS made by Nihon Seimitsu Optical Co., Ltd.), the visible light transmittance was measured by an integrating sphere that was completely diffused by the G filter at the transmission center wavelength λ = 550 nm. It was measured.

(2) Surface electric resistance value A sample cut into a width of 35 mm was placed on a rubber sheet having a rubber hardness of about 60, and two measuring electrodes made of two 2 mm thick palladium plates were set at a distance of 35 mm at a position orthogonal to the sample. After placing the sample, a load of 500 g was applied, and the resistance value between the electrodes was directly read using a digital tester (VOAC707 manufactured by Iwasaki Tsushinki).

(3) Adhesion of the conductive layer After the surface of the sample is cut by 1 mm square, cellophane adhesive tape (“Cellotape” manufactured by Nichiban Co., Ltd. JIS-Z1522)
A standard product) was subjected to a peel test in the 180 ° direction, and grade 5:
No peeling, 4th grade: 25% peeling, 3rd grade: 50% peeling, 2
Grade: 75% peeling, 1st grade: whole surface peeling, and grade judgment was performed.

(4) Adhesive strength of protective layer (a) Wetting index According to JIS K6768-1977 "Test method for wetting polyethylene and polypropylene film". Wetting index 40
If it is less than dyne / cm, poor adhesion often occurs.

(b) Adhesive Strength with Polycarbonate Resin As one method for evaluating the adhesive strength with a conductive paint for making a circuit, a polycarbonate resin ("Panlite" L1250 manufactured by Teijin Ltd.) was dissolved in a mixed solvent of tetrahydrofuran / benzene. The product was applied onto the protective layer (C) so as to have a solid content thickness of about 25 μm and dried at 150 ° C. for 10 minutes, and then the adhesive force of the coating film was measured by a tensile tester.

(5) Abrasion resistance Using a Gakushin type friction fastness tester, a head for friction (Kanamin No. 3 cotton cloth wound) is loaded on the protective layer (C) with a load of 500 g.
After rubbing 100 times / cm ² (200 times), the appearance of the protective layer (C) was inspected and judged by the rate of change of surface electric resistance.

(R ₀ : initial value, R ₁₀₀ : value after 100 double rubs) (6) ESCA method Measurement of binding abundance An ESCALAB-5 device manufactured by Vacuum Generator Scientific was used. The measurement conditions are as follows.

X-ray source Al-K _α- ray output 10kV-20mA Measurement vacuum degree 4 × 10 ^-8 mbar That is, X-rays are radiated on the sample surface placed in a high vacuum,
The photoelectrons emitted from the surface are detected by energy splitting with an analyzer. The binding energy of the bound electrons in the substance is obtained as a spectrum, and the binding state can be determined from the energy shift of each peak. The binding states and energy peaks are as follows.

Ti-O ^* -Ti: 530.1eV Ti-O ^* -Si: 531.4eV Si-O ^* -Si: 532.6eV The above bond ratio was calculated from these spectroscopic intensities.

〔Example〕

Example 1 A biaxially stretched polyethylene terephthalate film (thickness 0.1 mm, visible light transmittance 87%) was coated with In ₂ O ₃ / S.
Indium tin oxide having a composition of nO ₂ = 90/10 was deposited by the sputtering method. Sputtering was performed at a vacuum degree of 10 ⁻³ Torr under the introduction of argon gas. Adhesive film thickness is about 200Å, surface electric resistance value is 5 × 10 ² Ω /
□, visible light transmittance was 86%. Tetrabutyl silicate (Si (OC ₄ H ₉ ) ₄ ) is formed on the transparent conductive film above.
A silanol compound obtained by hydrolysis of
A butanol / toluene solution (concentration about 1%) of various mixing ratios of tetrobutyl titanate (Ti (OC ₄ H ₉ ) ₄ ) is applied with a metalling bar at a solid content of about 1,000Å at 140 ° C. I cured for 10 minutes. The obtained film was used as Sample No. 1 to No. 3 and various characteristics were evaluated.
The results in the table were obtained. From the protective layer Was found to be present at 33-51 mol%.

Comparative Example 1 Same as the above Example except that the silanol compound obtained by hydrolyzing tetrobutyl silicate (Si (OC ₄ H ₉ ) ₄ ) with dilute hydrochloric acid alone was used as the protective film component in Example 1. The laminated film prepared by the above method was evaluated in the same manner as in Sample No. 4 and Example 1, and the results shown in Table 1 were obtained.

Comparative Example 2 A laminated film prepared in the same manner as in the above-mentioned Example except that tetrobutyl titanate (Ti (OC ₄ H ₉ ) ₄ ) was used alone as a protective film component in Example 1 was used as a sample N.
The same evaluation as in Example 1 was carried out with 0.5, and the results shown in Table 1 were obtained.

Comparative Example 3 A laminated film prepared in the same manner as in the above Example except that the protective film was not provided in Example 1 was used as Sample N.
The same evaluation as in Example 1 was performed with the result of 0.6, and the results shown in Table 1 were obtained.

As can be seen from the comparison of the characteristic values of Sample Nos. 1 to 6 in Table 1, Sample Nos. 1 to 3 having the constitution of the present invention significantly improve the surface strength and abrasion resistance of the transparent conductive film, A)
Since the adhesiveness of / transparent conductive layer (B) / protective layer (C) is improved, the transparent conductive layer does not separate from the substrate, and the protective film (C) is formed in various processing steps for forming the transparent electrode. Since the adhesion with the conductive paint for circuit making was improved, the trouble of poor quality could be completely eliminated.

On the other hand, sample No. 6 without a protective film and sample Nos. 4 and 5 with a protective film other than the composition of the protective film of the present invention.
Is inferior in surface strength and abrasion resistance to the transparent conductive film as compared with that of the present invention, but the protective film (C) in various processing steps for forming the transparent electrode and the conductive paint for circuit formation are used. Had poor adhesion.

Claims (1)

[Claims] 1. A transparent conductive laminate comprising a substrate (A) made of an organic polymer, a transparent conductive layer (B) containing indium oxide as a main component, and a protective layer (C), which are laminated in this order. The protective layer (C) is composed of a three-dimensional copolymer obtained by copolymerizing a tetraalkyl titanate and a hydrolyzate of an organoalkoxysilane. In the bond (M ₁ and M ₂ are Si or Ti), The transparent conductive laminate, wherein the proportion of bonds is 15 to 70 mol%.