KR100418508B1 - Conductive Polymer Hard Coating Film with Excellent Transparency and Conductivity - Google Patents

Abstract

The present invention uses a polythiophene conductive polymer solution and an organic solvent such as amides, alcohols, aldehydes or ketones and a water-soluble or alcohol-soluble polymer compound as a primary coating layer for the substrate, and a silica sol solution as a secondary coating layer It is to provide a conductive polymer hard coating film excellent in transparency and conductivity prepared by using.

The transparent conductive coating film prepared in the present invention can be used for computer and TV CRT glass surface or safety glasses surface, clean room wall, hand carrier surface in electronic factory, CPP and PET film, PC and PMMA sheet surface, mobile phone housing, PVC resin, etc. have.

Description

Conductive polymer hard coating film with excellent transparency and conductivity

The present invention relates to a conductive polymer hard coating film having excellent transparency and conductivity. More specifically, a polythiophene conductive polymer solution, an organic solvent such as amides, alcohols, aldehydes or ketones, and a water-soluble or alcohol-soluble polymer compound are used as the primary coating layer, and a silica sol solution is used as the secondary coating layer. The present invention relates to a conductive polymer hard coating film having excellent transparency and conductivity.

The hard coating film having transparency and conductivity prepared according to the present invention is useful as an antistatic, electromagnetic shielding coating material.

It is known that only the metal can conduct electricity. However, since the electrical conductivity of polyacetylene doped with iodine (10 ³ S / cm) was confirmed in 1977, it was similar to that of metal. Has been studied.

Currently, conductive polymer compounds that are widely studied are polyaniline, polypyrrol, polythiophene, and the like, and these compounds are easy to polymerize and have excellent conductivity and oxidative stability, so that they can be used as electrodes and electrodes of secondary batteries. It is used for shielding materials, flexible electrodes, antistatic materials, anticorrosion coating materials and the like.

In particular, in recent years, as the shielding standards of electric waves generated from home, office, industrial, and electronic products such as computers, wireless telephones, automobiles, medical devices, and multimedia are strengthened, the conductive polymer coating composition is used for computer monitor screen glass or safety glasses, TV CRT, Attention has been drawn to electromagnetic wave shielding coating materials and antistatic coating materials applicable to transparent plastic panels, plastic housings, polyethylene terephthalate (PET) films, and the like.

U.S. Patent Nos. 5,035,926 and 5,391,472 describe a water soluble polyethylene dioxythiophene (PEBT) having excellent conductivity and transparency. These conventional water soluble PEDT conductive polymers have excellent conductivity and can be used as electromagnetic shielding and antistatic coating materials, but the film formed when coating on the surface of synthetic resin, glass, metal, etc. is poor in dispersion, and the conventional conductive polymer Its own color makes it difficult to use on transparent substrate surfaces.

In order to overcome this, it is coated with a thin film, but in this case, there is a problem in that the conductivity and hardness are lowered. The application of electromagnetic shielding and antistatic coating, which requires transparency, conductivity and hardness by thin film coating, is mainly used for computer and TV CRT glass surface or safety glasses surface, clean room wall, hand carrier in electronic factory. Surfaces, and other special-purpose casting polypropylene (CPP), PET film surface coatings.

Electromagnetic waves are coated on the surface of synthetic resin films, acrylic resins, and polycarbonate resins, such as glass surfaces (for example, computer screens, TV CRTs), PET and polypropylene (PP), using existing water-soluble or alcohol-soluble PEDT conductive polymers. When providing a shielding and antistatic function, the existing conductive polymer was coated alone or using a binder. In this case, its use is restricted where transparency is required because of the colorability of the conductive polymer.

When the amount of the conductive polymer is reduced in order to reduce the colorability of the coating film, the surface conductivity tends to decrease rapidly. A bigger problem than this is that the coating hardness is less than the pencil hardness B, so that scratching and damage easily occurs even in the case of external weak contact and impact. In order to supplement the coating hardness, a tetrafunctional group, for example, tetraethoxysilicate, is used, but in this case, since plasticity is generally performed at 150 ° C. or higher, it is not applicable to a synthetic resin such as polymethacrylate resin.

The present inventors use a polythiophene conductive polymer solution, an organic solvent such as amides, alcohols, aldehydes or ketones, and a water-soluble or alcohol-soluble polymer compound as the primary coating solution, and the silica sol solution which can be baked at low temperature with the secondary coating solution. Was used to completely solve the problem. The transparent conductive hard coating film prepared in this way has high conductivity and exhibits excellent conductivity and excellent transmittance even when coated with a thin film using a small amount.

In addition, the coating film thus formed is excellent in adhesion to the substrate, and the coating of the silica sol solution calcinable at a low temperature on the upper portion can be obtained a coating film with excellent hardness.

An object of the present invention is to provide a hard coating film having excellent permeability and conductivity using a polythiophene-based conductive polymer solution.

Another object of the present invention is to provide a hard coating film having excellent transparency and conductivity using an amide organic solvent in order to improve conductivity of a polythiophene-based conductive polymer.

Another object of the present invention is to provide a transparent and conductive hard coating film using a water-soluble or alcohol-soluble polymer compound in order to impart dispersibility of the conductive polymer and adhesion of the coating substrate.

Another object of the present invention is a hard coating film having excellent transparency and conductivity by forming a conductive layer on a substrate as a primary and providing a hardness as a secondary layer, and by forming a silica sol layer which can be baked at a low temperature. It is to provide.

Another object of the present invention is to coat on a variety of resins, such as glass, polymethylmethyl acrylic resin, polyacrylic resin, polycarbonate resin, PET resin, PVC resin, to provide an electromagnetic shielding and antistatic coating film excellent in transparency and conductivity will be.

The hard coating film having excellent transparency and conductivity of the present invention is a polythiophene-based conductive polymer solution on a substrate, an alcohol, an aldehyde or a ketone as a main solvent, an amide as a co-solvent and a water-soluble or alcohol-soluble polymer compound as a binder. The conductive layer which is a coating liquid is formed, The silica layer which is a secondary coating liquid which consists of a silica sol solution is formed on the said conductive layer.

In the present invention, the composition of the primary coating solution is composed of a polythiophene conductive polymer solution, an organic solvent, alcohols, aldehydes, ketones or amides, and a water-soluble or alcohol-soluble polymer compound as a binder.

An example of a conductive polymer used in the present invention is a Baytron P solution commercialized in 1.3 wt% Bayer Inc. containing a dopant, which is doped with polystyrenesulfonic acid (PSSA) as a dopant, so that it is soluble in water. In addition to its characteristics, it has excellent thermal and atmospheric safety. The Baitron P can be easily coated because it is mixed well with a solvent such as alcohol, aldehydes, ketones, amides, and even when the coating film is formed, it shows excellent permeability compared to other conductive polymers such as polyaniline and polypyrrole. In addition, Baitron M (M) and Baitron C (C) manufactured by Bayer Corp. under the organic solvent, for example, the weight of 1: 6 under the conditions of methanol, ethanol, isopropanol, butanol, acetonitrile, acetone, MEK, etc. PEDT prepared by mixing in%, or PEDT prepared by mixing in a ratio of 1: 6 in the absence of an organic solvent can be used. The amount of the conductive polymer used is 0.1 to 50% by weight, preferably 1 to 30% by weight. If the content is less than 0.1% by weight, the surface resistance is 10 ¹⁰ Ω or more, and when the content is greater than 50% by weight, the colorability is increased. The increase in the transmittance of the coating film with the increase in the conductive high molecular weight is less than 75% is undesirable.

The organic solvent is divided into a main solvent for the purpose of dissolving a water-soluble or alcohol-soluble polymer compound, which is a conductive polymer solution and a binder, to impart a coating property to the substrate, and a cosolvent for the purpose of improving the conductivity of the conductive polymer solution. As the main solvent, an alcohol solvent having 1 to 4 carbon atoms or less, for example, methanol, ethanol, propanol, isopropanol, butanol may be used. In addition, aldehydes and ketones represented by the following general formula (1) are preferable. Acetaldehyde, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and the like. And the usage-amount is 15-159.5 weight%.

[Formula 1]

R ₁ -C (O) -R ₂

Here, R ₁ is H or C ₁ to C ₁₀ alkyl group or aryl group, R ₂ is C ₁ to C ₁₀ alkyl group or aryl group.

When the main solvent is used in less than 15% by weight, the coating film is poor in dispersibility, and when used in excess of 99.5% by weight, the surface resistance of the coating film may not perform an antistatic function of 10 ⁶ Ω or more.

The main solvent may be alcohol, aldehydes, ketone solvents may be used alone, or mixed with each other, but most preferably it is used by mixing two to three alcohol solvents having different boiling points. In this case, the solvent may be sequentially evaporated after coating to form a coating film having excellent dispersibility of the conductive polymer.

In the present invention, the co-solvent used to improve the conductivity of the conductive polymer solution is preferably an amide organic solvent, and the structure means a solvent having an amide group [-N (R) -C = 0] in the molecule. For example, for example, formamide (FA), N-methylformamide (NMFA), N, N-dimethylformamide (DMF), acetamide (AA), N-methylacetamide (NMAA), N, N -Dimethylacetamide (DMA), N-methylpropionamide (NMPA), N-methyl pyrrolidone (NMP), dimethylamide (DMF), and the like.

The amide solvent may be used alone or in combination of two or more, the amount of the amide solvent is 0.01 to 20% by weight, preferably 0.1 to 10% by weight. When the amount of the solvent used exceeds 20% by weight, the temperature of the high-boiling amide organic solvent must be increased as the amount of the amide organic solvent increases, which causes a disadvantage that the conductive polymer is damaged by heat. In this case, the conductivity improving function of the conductive polymer solution is lost.

In order to impart dispersibility and substrate adhesion of the conductive polymer solution, an aqueous solution or an alcohol-soluble polymer resin is used as a binder. Examples of the binder include polymethyl methacrylate, polyacrylate, polyvinyl alcohol, polyvinyl acetal, Polyvinyl butyl al, methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, polyvinylacetate and the like. The amount used is 0.01 to 15% by weight, preferably 0.05 to 5% by weight.

When the amount of the binder exceeds 15% by weight, the coating film does not dry properly in a short time during low-temperature firing. On the contrary, when the amount of the binder is less than 0.01% by weight, the adhesion to the substrate is lowered.

When the primary conductive coating solution as described above is coated on a glass, polyacrylic resin, polycarbonate resin, PET resin, PVC resin as a substrate and dried at about 70 minutes for about 5 minutes, the surface resistance is 10 ¹ to 10 ¹⁰ Ω / □ The coating film having a transmittance of 75% or more can be obtained.

The excellent transparent conductive coating film prepared in the present invention reinforces the hardness by applying a secondary coating with a silica sol solution. First, the conductive coating solution is first applied and low temperature baked, and then coated with a silica sol capable of reinforcing hardness secondly and then subjected to low temperature annealing to obtain a coating film having excellent hardness of 4H or more.

The silica sol solution used in the present invention is prepared by performing a hydrolysis and condensation reaction of a mixed solution of methyl tri-methoxy silane and tetraethoxy silane having a tri- and tetra-functional groups.

The polymer is added with an organic coupling agent such as methacryloxypropyl trimethoxy silane, glycidoxypropyl triethoxy silane or vinyltrimethoxy silane to maintain adhesion with the substrate to be coated, that is, the coating. Can be used. At this time, the important point is to maintain the reaction temperature at 10 ℃ or less in the process of hydrolyzing the organic coupling agent so that the polymer and the gel do not form.

It is impossible to use the composition obtained as it is because it is not only poor in safety but also too high in viscosity. Therefore, it is diluted to an organic solvent so that the total solid content is 15% by weight or less, and the organic solvent used is a lower alcohol such as methanol, ethanol, isopropanol or an ether organic solvent such as ethylene glycol monoethyl ether or propylene glycol monomethyl ether. Can be used. When the composition is applied to the coated material according to a general coating method, for example, bar coating, spray coating, spin coating, and the like, and then thermally cured at a low temperature of 120 ° C. or less, a hard coating film having high transparency and excellent conductivity is obtained. Will be obtained.

Hereinafter, the present invention will be described in more detail based on Examples.

Examples 1-5

Next, the mixed solution prepared according to the composition shown in Table 1 was stirred for about 2 hours, washed thoroughly with methanol, coated with a 25 μ bar code on the dried polyacrylic plate surface, and about 5 minutes in an oven at 75 ° C. It dried to prepare a primary coating film. The thickness of this dried coating film was all 1 micrometer or less.

In the following Table 1, the conductive polymer aqueous solution is polyethylenedioxythiophene (PEDT), which is a polythiophene-doped polystyrene-sulfonate (PSS), and the sample is Bayer P. 4071 (trade name) of the aqueous solution. Parts by weight), NMP was used as the amide solvent, polyacrylic acid (PAA) as the binder, and methanol was used as the solvent.

The physical properties of the primary coating film obtained above are shown in Table 1 below, and the surface resistance per unit area was evaluated using a multimeter, and the transmittance was evaluated by a transmittance of 550 nm using a UV-visible spectrometer. It evaluated as pencil hardness.

Comparative Examples 1 to 4

Next, except that a primary coating film was prepared using the mixed solution prepared according to the composition shown in Table 1, the same procedure as in Example 1 was carried out, but in Comparative Examples 3 and 4, polyvinyl alcohol (PVA) was used as the binder.

Evaluation of physical properties of the primary coating film obtained above is shown in Table 1 below.

TABLE 1

Examples 6-10

It was carried out in the same manner as in Example 1 except for preparing a primary coating film using a mixed solution prepared according to the composition shown in Table 2. Evaluation of physical properties of the resulting primary coating film is shown in Table 2 below.

In the following Table 2, the conductive polymer solution is a polythiophene-based polyethylenedioxythiophene (PEDT) doped with polystyrene sulfonate (PSS), and the sample is Bayer's Baitron P (trade name) 4071 (solid content 1.5) Parts by weight), NMP was used as the amide solvent, polyacrylic acid (PAA) as the binder, methanol was used as the solvent.

TABLE 2

Examples 11-19

On the surface of the primary coating film prepared in Examples 2, 4 and 5, a silica sol solution, which is a secondary coating solution having a solid content concentration as shown in the following Table 3, was applied with a bar code of 25 μ, and then, in a 75 ° C. oven, about 5 It was dried about a minute. The thickness of the dried coating film was all 1μ or less, and the measurement results of the physical properties of the resulting coating film are shown in Table 3 below.

Here, the silica sol solution was prepared by the following method.

100 g of a mixed solution of methyl tri-methoxy silane and tetraethoxy silane having tri- and tetra-functional groups, 60 g of IPA, 60 g of tertiary distilled water, 1 g of hydrochloric acid, and 10 g of methacryloxypropyl trimethoxy silane were added. Stir and mix for 24 hours at ℃. This was again diluted in IPA to adjust the solids concentration to 5%, 10% and 15%.

TABLE 3

According to the present invention, a silica sol which is calcinable at low temperature with a secondary coating solution using a polythiophene conductive polymer solution, an organic solvent such as amides, alcohols, aldehydes or ketones, and a water-soluble or alcohol-soluble polymer compound as a primary coating solution. The transparent conductive hard coating film prepared by using a solution has high conductivity, and is characterized by exhibiting excellent conductivity and excellent transmittance even when coated with a thin film using a small amount.

The transparent conductive coating film prepared in the present invention can be used for computer and TV CRT glass surface, or safety glasses surface, clean room wall, hand carrier surface in electronic factory, CPP and PET film, PC and PMMA panel surface, mobile phone housing, PVC resin, etc. have.

Claims (8)

In a conductive polymer hard coating film in which a polythiophene-based solution and a silica sol solution are coated in a layer on a substrate surface, the polythiophene-based solution is 0.1-50% by weight of polyethylene dioxythiophene solution, alcohols, aldehydes and ketones. 15 to 99.5% by weight of a solvent selected from the group consisting of, a mixture of 0.01 to 20% by weight of an amide solvent, and 0.01 to 15% by weight of a water-soluble or alcohol-soluble polymer compound, the silica sol solution is 3 A conductive polymer hard coating film having excellent transparency and conductivity, which is prepared by hydrolyzing and condensing a functional group, a tetrafunctional silane compound, and an organic coupling agent. The conductive polymer hard coating film of claim 1, wherein the substrate is selected from glass, polymethylmethylacrylic resin, polyacrylic resin, polycarbonate resin, PET resin, or PVC resin. The conductive polymer hard coating film of claim 1, wherein the polyethylene dioxythiophene is doped with polystyrene sulfonate. The method of claim 1, wherein the solvent is lower alcohols having 1 to 4 carbon atoms of methanol, ethanol, propanol, isopropanol or butanol, aldehydes of acetaldehyde represented by the following formula (1), and acetone, methyl ethyl ketone or A conductive polymer hard coating film having excellent transparency and conductivity, characterized by selecting at least one from the group consisting of ketones of methyl isobutyl ketone. Formula 1 R ₁ -C (0) -R ₂ Here, R ₁ is H or C ₁ to C ₁₀ alkyl group or aryl group, R ₂ is C ₁ to C ₁ 0 alkyl group or aryl group. The amide solvent of claim 1, wherein the amide solvent is formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, A conductive polymer hard coating film having excellent transparency and conductivity, characterized by selecting at least one of N-methyl pyrrolidone and dimethylamide. The method of claim 1, wherein the water-soluble or alcohol-soluble polymer resin is polymethyl methacrylate, polyacrylate, polyvinyl alcohol, polyvinyl acetal, polyvinyl butyl al, methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose or A conductive polymer hard coating film having excellent transparency and conductivity, which is selected from polyvinylacetate. The conductive polymer hard coating film of claim 1, wherein the trifunctional and tetrafunctional silane compounds are methyltri-methoxy silane and tetraethoxy silane, respectively. The conductive polymer hard coating film having excellent transparency and conductivity according to claim 1, wherein the organic coupling agent is selected from methacryloxypropyl trimethoxysilane, glycidoxy propyl triethoxy silane or vinyltrimethoxy silane. .