JPH01261469A - Transparent conductive coating film - Google Patents

Abstract

PURPOSE:To obtain the title film having improved surface hardness, durability, transparency, conductivity, and antistatic properties, by mixing specified fine conductive particles with a vehicle and forming a coating film from this mixture. CONSTITUTION:100 pts.wt. fine conductive particles having a mean particle diameter of 10Angstrom -5mum and preferably comprising SnO2 (optionally doped with Sb) or a mixture of SnO2 with In2O is surface treated with at least 0.01 pt.wt. carbosilane coupling agent of formula I (wherein R<1-3> are each H, alkyl, alkenyl, aryl, or a hydrocarbon group having halogen, epoxy, glycidoxy, amino, mercapto, methacryloxy or cyano; a and b are each 0-1) to give a component. This component is mixed with a vehicle preferably comprising an organosilicon compound (hydrolyzate) of formula II (wherein R<4> and R<5> are each alkyl, alkenyl, aryl, or a hydrocarbon group having halogen, epoxy, glycidoxy, amino, mercapto, methacryloxy or cyano; X is a hydrolyzable group; c and d are each a). The mixture is applied to a transparent base material to form a coating film thereon, thus giving the title film having a thickness of 0.1-50mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a transparent coating having excellent surface hardness, electrical conductivity, and antistatic properties. In particular, the present invention relates to a transparent conductive film that has excellent durability since it is possible to increase the thickness of the film.

[Prior Art] The most suitable transparent conductive coatings are metal thin films such as gold, silver, and aluminum, as well as tin oxide, antimony-doped tin oxide, and a composite oxide of indium oxide and tin oxide (abbreviated as ITO). well known. on the other hand,
Antistatic coatings that use various ionic compounds such as cationic or anionic compounds in addition to the above-mentioned conductive coatings are known.

[Problems to be Solved by the Invention] Transparent conductive coatings made of thin metal films such as gold, silver, and aluminum have drawbacks such as low hardness and absorption of visible light. Furthermore, films made of tin oxide, ITO, etc. are usually formed by methods such as sputtering, thermal CVD, and vacuum evaporation, which makes it extremely difficult to produce thick films and is unrealistic in terms of cost. . In other words, since transparent conductive films made of metal thin films and metal oxide thin films are both very thin films, if they collide with something made of a slightly harder material or are abraded, they will be scratched and cause serious damage such as disconnection of the conductive film. There are drawbacks.

On the other hand, antistatic coatings using ionic compounds have the disadvantage that their antistatic performance is greatly affected by environmental changes such as humidity, and that they do not exhibit their function particularly at low humidity.

An object of the present invention is to provide a transparent conductive film that has high surface hardness, excellent durability, and exhibits no deterioration in performance even at low humidity.

[Means for Solving the Problems] The present invention has the following configuration to achieve the above object.

[A transparent conductive film characterized by being mainly composed of conductive fine particles surface-treated with a carbon-containing silane coupling agent and a vehicle. ” In the present invention, the substrate on which the transparent conductive coating is provided is not limited in any way as long as it requires the present invention, but since the coating obtained by the present invention is transparent, it may also be used as a substrate. Application to transparent substrates is preferred. Further, there is no problem whether the base material S is inorganic glass or organic plastic. Further, the shape of the base material is not particularly limited, such as a flat plate, a curved shape, or a circular shape. In addition, products in which a transparent conductive film made of a thin metal film or a thin film of a metal oxide such as ITO or tin oxide is provided on the entire surface or a part of the surface of the base material are also intended for applications such as handwriting input devices. preferred.

Next, the conductive fine particles in the present invention are not particularly limited as long as they can provide sufficient transparency and conductivity when formed into a film, but they can have both high conductivity and transparency. Preferred examples include tin oxide (including antimony doped materials) and indium oxide/tin oxide mixtures from the viewpoint of satisfactory freshness. Furthermore, the average particle diameter of such conductive fine particles may be any size as long as it can achieve the above-mentioned purpose, but in particular, from the viewpoint of stabilizing the dispersion state and easily obtaining a uniform coating, primary particles of 10 angstroms to 5 μm are preferred. It is preferable to have a diameter. Here, the secondary particle size means a particle size that can be substantially dispersed by some dispersion method. In addition, such conductive fine particles usually have a 30%
Preferably, 90% by weight is contained in the coating.

That is, if it is less than 30% by weight, sufficient conductivity cannot be obtained, and if it is more than 90% by weight, appearance such as transparency, and even adhesiveness with the base material, etc. tend to deteriorate.

The surface of the conductive fine particles used in the present invention must be treated with a carbon-containing silane coupling agent. That is, treatment with a silane coupling agent improves the dispersibility of the conductive fine particles and improves the surface hardness. As for the state of the treated fine particles, it is preferable that the surface of the fine particles be covered with a chemically bonded state of a silane coupling agent, from the viewpoint of stability of the treatment and a large effect of the treatment. Also,
It may be covered with a film obtained by a silane coupling agent.

In addition, such a carbon-containing silane coupling agent has at least a carbon-containing organic group through a -S+-C- bond, and the amount of treatment for these conductive fine particles depends on the particle size of the fine particles and compatibility with the vehicle. The conductive fine particles should be determined by
It is preferably 0.01 part by weight or more, more preferably 0.05 part by weight or more. In addition, from the viewpoint of maintaining conductivity, conductive fine particles 100
It is preferably 5.00 parts by weight or less, more preferably 3 parts by weight or less.

The conductive fine particles treated with such a carbon-containing silane coupling agent include, from the viewpoint of treatment stability and ease of treatment, such a silane coupling agent.
It is preferable that the functional group is present on the surface of the conductive fine particles to be treated as a functional group represented by the following general formula (A>).

RIR2R3b Si 0(3-a-b)
(A) (wherein R1, R2, and R3 are each at least one selected from hydrogen, an alkyl group, an alkenyl group, an aryl group, or a halogen, an epoxy group, a glycidoxy group, an amino group, a mercapto group, a methacryloxy group, and a cyan group) A hydrocarbon group having one substituent, a and b
is 0 is 1. ) Various methods can be applied to the silane coupling agent treatment. In particular, organosilicon compounds capable of producing a functional group of general formula (A>), such as alkoxysilanes having a substituent corresponding to general formula (A), especially lower alkoxysilanes such as methoxy and 1-oxy, and acetoxysilane. Organosilicon compounds having hydrolyzable functional groups such as acyloxysilanes, chlorosilanes, halogenosilanes, silazane compounds, ketoximesilanes, and isopropenylsilanes are prepared in a gas phase, without a solvent, or in various solvents. It is most preferable to treat the surface in a liquid phase and cause a hydrolysis reaction during and/or after the treatment because it is simple and allows uniform treatment.

Note that during the treatment, it is also effective to perform the treatment at a high temperature by heating or the like.

In the present invention, conductive fine particles surface-treated with the above-mentioned carbon-containing silane coupling agent are contained in various vehicles to form a film. Any material may be used, but since the conductive fine particles are generally inorganic substances treated with a silane coupling agent, and in particular their inorganic oxides, the following substances have a good affinity with these particles and can provide high hardness. An organosilicon compound represented by general formula (B) and/or a hydrolyzate thereof are preferably used.

R4c R” dS 1(X) 4-C-d (B
) (In the formula, R4 and R5 are each an alkyl group, an alkenyl group, an aryl group, or a hydrocarbon group having a halogen, an epoxy group, a glycidoxy group, an amino group, a mercapto group, a methacryloxy group, or a cyan group, and X is a hydrolyzable (C and d are O or 1) Specific representative examples of the organosilicon compound represented by the general formula (B) and/or its hydrolyzate include methyl silicate, ethyl silicate, n- Tetraalkoxysilanes such as propyl silicate, i-propyl silicate, 0-butyl silicate, 5ec-butyl silicate and t-butyl silicate, and their hydrolysates, as well as methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxy silane,
Methyltriacetoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane,
Phenyltriethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-
Chloropropyltriethoxysilane, γ-chloropropyltriacetoxysilane, 3.3.3-trifluoropropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxy Silane, γ
-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, β-
Cyanoethyltriethoxysilane, methyltriphenoxysilane, tetraromethyltrimethoxysilane, chloromethyltriethoxysilane, glycidoxymethyl l-liftoxysilane, glycidoxymethyltriethoxysilane, α-glycidoxyethyltri Methoxysilane, α-glycidoxyethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltrimethoxysilane Ethoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltribropoxysilane, γ-glycidoxypropyltributoxysilane, γ-glycidoxypropyltrimethoxyethoxysilane , γ-glycidoxypropyltriphenoxysilane, α-glycidoxybutyltrimethoxysilane, α-glycidoxybutyltriethoxysilane, β-glycidoxybutyltrimethoxysilane, β
-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, ( 3,4-epoxycyclohexyl)methyltrimethoxysilane, (3,4-epoxycyclohexyl)methyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3
, 4-Epoxycyclohexyl)ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltripropoxysilane, β-(3,4-epoxycyclohexyl)ethyltributoxysilane, β-(3,4-
Epoxycyclohexyl)ethyltrimethoxyethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriphenoxysilane, γ-(3,il-epoxycyclohexyl)propyltrimethoxysilane, γ-(3
, 4-epoxycyclohexyl)propyltriethoxysilane, β-(3,4-epoxycyclohexyl)butyltrimethoxysilane, β-(3,4-epoxycyclohexyl)butyltriethoxysilane, and other trialkoxysilanes and triazyloxysilanes. , or triphenoxysilanes or their hydrolysates and dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyljethoxysilane, phenylmethyljethoxysilane, γ-chloropropylmethyldimethoxysilane, γ
-Chloropropylmethyljethoxysilane, dimethyldiacetoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyljethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyljethoxysilane , γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyljethoxysilane, methylvinyldimethoxysilane, methylvinyljethoxysilane, glycidoxymethylmethyldimethoxysilane,
Glycidoxymethylmethyljethoxysilane, α-glycidoxyethylmethyldimethoxysilane, α-glycidoxyethylmethyljethoxysilane, β-glycidoxyethylmethyldimethoxysilane, β-glycidoxyethylmethyljethoxysilane , α-glycidoxypropylmethyldimethoxysilane, α-glycidoxypropylmethyljethoxysilane, β-glycidoxypropylmethyldimethoxysilane, β-glycidoxypropylmethyljethoxysilane, γ-glycid Xypropylmethyldimethoxysilane, γ-glycidoxypropylmethyljethoxysilane, γ-glycidoxypropylmethyldiproboxysilane, γ-glycidoxypropylmethyldibutoxysilane, γ-glycidoxypropylmethyldimethoxyethoxy Silane, γ-glycidoxypropylethyldiphenoxysilane, γ-glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylethyljethoxysilane, γ-glycidoxypropylethyldibropoxysilane, γ- Dialkoxysilane or dimethoxysilane such as glycidoxypropylphenyldimethoxysilane, γ-glycidoxypropylvinyldimethoxysilane, γ-glycidoxypropylphenyldimethoxysilane, γ-glycidoxypropylphenyldiethoxysilane, etc. Acyloxysilanes or their hydrolysates are examples.

These organosilicon compounds can be used alone or in combination of two or more.

These organosilicon compounds are preferably used after being hydrolyzed in order to lower the curing temperature and further promote curing.

Hydrolysis is produced by adding and stirring pure water or an acidic aqueous solution such as hydrochloric acid, acetic acid, or sulfuric acid. Furthermore, the degree of hydrolysis can be easily controlled by adjusting the amount of pure water or acidic aqueous solution added. During hydrolysis, it is particularly preferable to add pure water or an acidic aqueous solution in an amount equal to or more than 3 times the mole of the hydrolyzable group of -maximum (B) from the viewpoint of accelerating curing.

During hydrolysis, alcohol and other substances are produced, so it is possible to hydrolyze without a solvent, but in order to make the hydrolysis more uniform, hydrolysis is performed after mixing the organosilicon compound and a solvent. It is also possible. Depending on the purpose, alcohol etc. after hydrolysis may be heated and/or
Alternatively, it is possible to remove an appropriate amount under reduced pressure and use it, or it is also possible to add an appropriate solvent afterwards.

Examples of these solvents include alcohols, esters, ethers, ketones, halogenated hydrocarbons, and aromatic hydrocarbons such as toluene and xylene.

Moreover, these solvents can also be used as a mixed solvent of two or more types as required. Furthermore, depending on the purpose, it is possible to accelerate the hydrolysis reaction and further advance reactions such as precondensation by heating above room temperature, or to suppress precondensation, the hydrolysis temperature can be lowered to below room temperature. Needless to say, it is possible to do so.

Although curing of such an organosilicon compound and/or its hydrolyzate is usually carried out by heating,
Various curing catalysts are added for the purpose of shortening heating time and curing at low temperatures. Examples of the curing catalyst include alkali metal salts of carboxylic acids and alkoxides or chelate compounds of aluminum, titanium, zirconium, and the like.

In particular, aluminum chelate compounds such as acetylacetone aluminum salt are preferably used from the viewpoint of composition stability, transparency, and absence of coloration.

In addition, among the organosilicon compounds represented by the above-mentioned maximum (B), R4 and R5 are alkyl groups having 1 to 4 carbon atoms, especially from the viewpoint of adhesion to the substrate, improvement of surface hardness, heat resistance, weather resistance, etc. An organic group having an alkenyl group, a phenyl group, an epoxy group, or a glycidoxy group is preferable.

It is preferable to add a dielectric colloidal inorganic oxide to the vehicle from the viewpoint of improving hardness and adhesion to inorganic base materials, especially inorganic glass, ITOv4, or inorganic glass having a tin oxide film. be done. Here, a specific example of the dielectric colloidal inorganic oxide is Si
, Ti, Al, Zr, Sb, W, Ta and other metal oxides, with an average particle diameter of 1.
Those having a wavelength of nm to 200 nm are preferably used.

Among these, Va group metal oxides such as sb are preferred for the purpose of improving conductivity.

As a coating means for coating the transparent curtain Murakami of the present invention, commonly used coating methods such as brush coating, dip coating, roll coating, screen printing, spray coating, spin coating, and flow coating can be easily used. It is.

The thickness of the coating in the present invention is not particularly limited. However, from the point of view of adhesive strength retention, hardness, etc.
It is preferably used between 1 μm and 50 μm. Particularly preferably, the thickness is 0.5 μm to 20 μm. In addition, when applying a film, it is diluted with various solvents for workability and film thickness adjustment. Examples of diluting solvents include water, alcohol, ester, ether, halogenated hydrocarbon, dimethylformamide, dimethyl sulfoxide, etc. Various solvents can be used depending on the purpose, and a mixed solvent can also be used if necessary. In addition, when using colloidal inorganic oxides such as antimony oxide, from the viewpoint of dispersibility etc., water, alcohol, dimethylformamide, ethylene glycol, diethylene glycol, triethylene glycol, benzyl alcohol, phenethyl alcohol, phenyl cellosolve, etc. is particularly preferably used.

In addition to the above-mentioned silicon compounds, the coating of the present invention may contain transparent resins such as various epoxy resins, melamine resins, acrylic resins, urethane resins, polymerized vinyl and its saponified products, nylon resins, and polyester resins. It can be used within the range without significantly impairing the properties or reducing the hardness. Moreover, the content of the vehicle contained in the coating is preferably 10 to 70% by weight in the entire coating.

That is, if the amount is less than this, there will be problems with appearance, adhesion to the base material, etc., and if it is more than this, there will be problems such as poor conductivity.

The film in the present invention is usually formed by applying a composition comprising the various components described above onto a substrate.

To form a film from these compositions, a coating composition containing these compositions is generally applied and then cured by dry soot by heating.

The curing temperature varies depending on the selected composition, working conditions, base material, etc., but is preferably 60°C to 300°C, preferably 80°C to
200°C is used. If the temperature is lower than this, curing will be insufficient, and if the temperature is higher than this, problems such as cracks and decomposition of the film will occur.

The conductivity and transparency of the film obtained by the present invention should be optimized depending on its intended use.
Considering application to ordinary transparent substrates, liquid crystal input devices, etc., a resistivity value of 5×10 5 Ω·mark or less and a haze value of 30% or less are preferably used. On the other hand, if the purpose is to prevent static electricity, the specific resistance value is less than 5X106Ω・mark.
Haze value is 80% or less, more preferably 1×106Ω・】
Below, 40% or less will be applied. Further, when a conductive pen such as a pencil is used for application to an input device, the surface roughness of the coating is preferably less than 2 μm in order to avoid leaving a drawing mark or to make it easy to remove. Here, the surface MU is measured by the method specified in JIS BO651.

As a method for dispersing each component in the present invention, stirring using a simple stirring blade is sufficient, but in order to improve the dispersion state, paint conditioners, sand mills, three-roll mills, ball mills, homo mixers, homogenizers, etc. can be used. is preferably used.

On the other hand, in order to maintain a stable dispersion state, it is preferable to add various surfactants, especially nonionic surfactants such as silicone surfactants, fluorine surfactants, and even phenyl ether surfactants. is preferably used.

Furthermore, by adding a dye or the like having a complementary color relationship to the color tone of the film, a transparent conductive film that does not show any color tone can be obtained.

The transparent conductive film obtained by the present invention has excellent transparency and surface hardness, and is useful as front plates of various displays such as window glasses, CR'l' and liquid crystal displays, or input device parts for these displays.

[Examples] Examples are given below to clarify the gist of the present invention, but the present invention is not limited to these Examples.

Example 1 (1) Preparation of silane hydrolyzate γ-glycidoxypropyltrimethoxysilane 30.2
g was cooled to 10° C., 6.9 g of 0001 N aqueous hydrochloric acid solution was gradually added dropwise with stirring, and after the dropwise addition was completed, stirring was continued for another 1 hour at room temperature to obtain a silane hydrolyzate.

(2) Preparation of coating agent Bisphenol A type epoxy resin (trade name: Epicoat 827, manufactured by Shell Chemical Co., Ltd.) 7 is added to the silane hydrolyzate.
．． 1g, N,N-dimethylformamide 22.1g, benzyl alcohol 10.0g, methyl alcohol 17.
1g of silicone surfactant and 1.5g of silicone surfactant were added and mixed.
Further, 29.7 g of colloidal tentimony pentoxide sol (trade name: antimony sol A-2550, manufactured by Nissan Chemical Co., Ltd.) and 2.2 g of acetylacetonaluminum salt were added and thoroughly stirred.

Further, as conductive particles, 10.0 g of indium oxide/tin oxide mixed inorganic oxide (ITO particles) whose surface was treated with trimethylmethoxysilane (carbon content 0.05%) and whose average particle diameter was 061 μm was added. Next, 395 g of phenethyl alcohol was added and thoroughly dispersed with a homogenizer to form a coating agent.

3) Application of coating agent and curing The coating agent described in the previous section was applied to a flat inorganic glass substrate with a thickness of 3 mm using a #16 bar coater.

After coating, it was set indoors for 5 minutes, and then heat cured at 80°C for 12 minutes and then at 130°C for 2 hours.

(4) Evaluation method (a) Paint film thickness , JfS BO651.

(D) Surface hardness 4HH brush hardness was measured according to JIS K5400, and the surface hardness was determined.

(c) Transmittance, measured using a haze direct-connected haze computer (manufactured by Suga Test Instruments Co., Ltd., model HG M-2).

(d) Sheet surface resistance value The surface resistance value was determined using the four-probe method.

(5) The transparent conductive film obtained as an evaluation result had good transparency, slight coloring, and was favorable in terms of appearance. Further, when this coating was subjected to a cloth abrasion charging test at a low humidity of 20% RH, it was confirmed that it had a very good antistatic effect.

Other physical properties are shown in Table 1.

Example 2 Example 1. , the thickness of the substrate is 1. The same procedure as in Example 1 was carried out, except that glass with a transparent conductive film (Nesa glass 110 Ω/hole) having a diameter of 1.5 mm was used, and the method of applying the coating agent was changed to a bar coater method and a spin coater method was used. The obtained conductive film is a film with excellent transparency as in Example 1, and also has excellent resistance to drawing input from the film surface.
Stable conduction was obtained over the entire surface of the coating between the conductive legs. Also, when drawn with an empi with hardness B, it is 2, 10,0
Even after 00 times, no scratches were generated, and a protective layer with excellent drawing durability was obtained. Other physical properties are shown in Table 1.

Example 3 The same procedure as in Example 2 was carried out except that the surface of the conductive fine particles was treated with hexamethyldisilazane (carbon content: 1.0%). The obtained transparent conductive film was a protective film with excellent drawing durability similar to that of Example 2. Other physical properties are shown in Table 1.

Example 11 In order to reduce the slight coloring caused by the conductive fine particles and vehicle in Example 1, PTF3-31 consisting of a pure pigment component was used as a complementary color dye of the conductive fine particles and vehicle.
(CI number Disperse-26) 0.012
g and PTV-57 (CI number Disperse-3
1) Example 1 except that 0.063 g was added and sufficiently dispersed with a homogenizer to form a coating agent.
I did it in the same way. The obtained film is colorless and transparent,
The degree of coloration (YI value) was reduced to 1/2. It was also confirmed that this film was a good antistatic film similar to Example 1. Other physical properties are shown in Table 1.

Comparative Example 1 Indium oxide without surface treatment in Example 1,
/Tin oxide-based mixed inorganic oxide (ITo fine particles) was used in the same manner as in Example 1. 14) The surface hardness of the transparent conductive coating was slightly insufficient at 61-■. Other physical properties are shown in Table 1.

Comparative Example 2 The same procedure as in Example 2 was conducted except that ITO fine particles without surface treatment were used. The resulting coating had excellent transparency and poor conductivity, but the surface hardness was 5H, which was slightly insufficient.

[Effects of the Invention] The transparent conductive film obtained by the present invention has the following effects.

1. A coating with high surface hardness is formed and has excellent drawing durability.

2. High transparency and excellent conductivity, making it useful for input devices.

3. Excellent antistatic properties even at low humidity.

Claims (2)

[Claims] (1) A transparent conductive film characterized by comprising as main components conductive fine particles surface-treated with a carbon-containing silane coupling agent and a vehicle. (2) The transparent conductive film according to claim (1), wherein the treatment with a carbon-containing silane coupling agent is performed using a compound having a silane functional group represented by the following general formula (A). R^1R^2_aR^3_bSiO_(_3_-_a_
-_b_)(A) (In the formula, R^1, R^2, and R^3 are each hydrogen, an alkyl group, an alkenyl group, an aryl group, or a halogen, an epoxy group, a glycidoxy group, an amino group, a mercapto group, or a methacrylic group. A hydrocarbon group having at least one substituent selected from an oxy group and a cyano group, and a and b
is 0 or 1. )