JPH07310033A - Photosetting electrically conductive coating material - Google Patents

Abstract

PURPOSE:To provide a conductive coating material containing a (meth)acrylate compound, indium oxide powder, a dispersing agent and a photopolymerization initiator at respective specific ratios, easily curable by ultraviolet rays, actinic rays, etc., and forming a coating film having excellent electrical conductivity, scratch resistance, etc. CONSTITUTION:This coating material contains (A) 100 pts.wt. of a (meth)acrylate compound having >=2 (meth)acryloyl groups in one molecule, (B) 200-500 pts.wt. of tin-doped indium oxide powder having an average particle diameter of 0.01-0.4mum, (C) 5-100 pts.wt. of a dispersing agent and (D) 0.01-20 pts.wt. of a photopolymerization initiator. Preferably, the component A is e.g. ethylene glycol di(meth)acrylate, the component C is e.g. polyvinyl acetal resin and the component D is a substance having light-absorption range in 350-400nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable conductive coating composition which can be easily cured by ultraviolet rays or actinic rays to form a coating film excellent in conductivity, transparency and scratch resistance.

[0002]

2. Description of the Related Art Conventionally, semiconductor wafer storage containers, electronic / electrical members, floor materials / wall materials for semiconductor manufacturing plants, etc.
Depending on its application, electrostatic charging is extremely disliked, and one having an antistatic property is used. Generally, in order to impart antistatic performance to a molded body made of a synthetic resin,
For example, a method of coating with a coating material containing carbon powder or metal powder, or kneading and blending carbon powder, carbon fiber, metal fiber or the like with a synthetic resin at the time of molding is performed. However, these methods have a problem that a transparent material cannot be obtained due to coloring of the paint or the molded body itself, and thus the content cannot be seen through when used in the window portion.

Therefore, JP-A-57-85866 discloses a transparent coating material containing a conductive fine powder containing tin oxide as a main component in a binder. This paint can form a coating film that is transparent and has antistatic properties, but since the binder is a thermoplastic resin, there is the problem that a coating film that is generally excellent in scratch resistance and solvent resistance cannot be obtained. there were.

Further, Japanese Patent Laid-Open No. 60-60166 discloses a transparent coating material containing a conductive fine powder containing tin oxide as a main component in a binder. This paint contains a component that cures with ultraviolet rays or visible light, and the coating film has good transparency and antistatic performance, and forms a coating film excellent in scratch resistance and solvent resistance.

With this coating material, a substrate having a relatively high surface hardness such as an acrylic resin can be provided with sufficient scratch resistance and transparency can be maintained even if the thickness of the coating film is reduced. However, for a substrate having a relatively low surface hardness such as vinyl chloride resin or polycarbonate, it is necessary to make the coating film thicker in order to impart sufficient scratch resistance, which causes a problem that transparency decreases. There was a point.

[0006]

The present invention has been made in view of the above problems, and an object thereof is to form a coating film by easily curing it with ultraviolet rays or visible rays, and to obtain the coating film obtained. Has excellent transparency, and therefore, it is to provide a photocurable conductive paint capable of forming a coating film having high scratch resistance and high transparency even when applied to a substrate having a relatively low surface hardness. .

[0007]

The photocurable conductive coating material of the present invention comprises a (meth) acrylate compound (a), an indium oxide powder (b), a dispersant (c) and a photopolymerization initiator (d). Become.

The (meth) acrylate compound (a)
Are those having at least two or more (meth) acryloyl groups in the molecule and include, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene. Glycol di (meth) acrylate, nonaethylene glycol di (meth)
Acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, nonapropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 2,2-bis [4-acryloxydiethoxyphenyl] propane, 2,2-bis [4-methacryloxydiethoxyphenyl] propane, 3-phenoxy-2-propanoyl acrylate, 1,6-bis (3-acryloxy-2-hydroxy Bifunctional (meth) acrylates such as propyl) -hexyl ether; pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, tris. Trifunctional (meth) acrylates such as (2-hydroxyethyl) -isocyanuric acid ester (meth) acrylate; pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate. And a tetra- or higher functional (meth) acrylate and the like.

Further, the above-mentioned (meth) acrylate compound (a) has a (meth) acryloyl group at the molecular end,
By adding an acrylic urethane oligomer having a urethane bond in the molecule, the abrasion resistance of the resulting coating film is further improved.

Such an acrylic urethane oligomer is prepared, for example, by reacting a compound having two or more isocyanate groups in one molecule with a (meth) acrylate having active hydrogen.

Examples of the compound having two or more isocyanate groups in one molecule include m-phenylene diisocyanate, p-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,5-diisocyanate and toluene-2. , 6-diisocyanate, toluene-3,5-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4′-diphenylmethane diisocyanate,
4,4'-diisocyanate-3,3'-dimethylbiphenyl, 4,4'-diisocyanate-3,3'-dimethylbiphenylmethane and the like can be mentioned.

As the (meth) acrylate having active hydrogen, for example, 2-hydroxyethyl (meth) acrylate is used.
Acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, glycerin di (meth) acrylate, 1,6-bis (3-acryloxy-2-hydroxypropyl) -hexyl ether, pentaerythritol tri ( Examples thereof include (meth) acrylate, tris- (2-hydroxyethyl) isocyanuric acid ester (meth) acrylate, and (meth) acrylic acid.

The tin-doped indium oxide powder (b) is used for imparting conductivity to the coating film, and when the average particle size is small, the conductivity of the resulting coating film is low and when it is large. It is limited to 0.01 to 0.4 μm because it scatters visible light and reduces the transparency of the coating film.

When the amount of the indium oxide powder (b) is small, the conductivity of the coating film is lowered and the antistatic effect is insufficient, and when it is large, the mechanical strength and transparency of the coating film are lowered, so (Meth) acrylate compound (a) 10
It is 200 to 500 parts by weight with respect to 0 parts by weight.

Further, in order to improve the dispersibility of the indium oxide powder (b), a surface treatment may be performed with a silane coupling agent, a titanium coupling agent, an aluminate coupling agent or the like.

The dispersant (c) is used for enhancing the dispersibility of the indium oxide powder (b) and improving the transparency. The dispersant (c) is represented by vinyl chloride or 75 to 98 mol% of a (meth) acrylic acid ester monomer represented by the following general formula (1), vinyl alcohol, and the following general formula (2). Hydroxyl group-containing monomer or hydroxyl group-containing monomer represented by the following general formula (3): 2 to 25 mol%
And a copolymer consisting of 0 to 18 mol% of another copolymerizable monomer; a polyvinyl acetal resin is used.

[0017]

[Chemical 1]

In the above general formula (1), R ¹ represents hydrogen or a methyl group, and R ² represents an alkyl group or an aryl group having 10 or less carbon atoms.

[0019]

[Chemical 2]

In the above general formula (2), R ³ is hydrogen or a methyl group, and m is an integer of 1-10.

[0021]

[Chemical 3]

In the above general formula (3), R ⁴ is hydrogen or a methyl group, n is an integer of 1 to 9, and k is an integer of 2 to 10.

Examples of the (meth) acrylic acid ester represented by the above general formula (1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid. Examples include butyl, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and phenyl (meth) acrylate. Moreover, halogen-substituted (meth) such as 2-chloroethyl (meth) acrylate
It may be an acrylate ester.

Examples of the hydroxyl group-containing monomer represented by the above general formula (2) include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate,
Examples thereof include hydroxybutyl (meth) acrylate and hydroxyoctyl (meth) acrylate.

Examples of the hydroxyl group-containing monomer represented by the above general formula (3) include polyethylene glycol mono (meth) acrylates such as triethylene glycol mono (meth) acrylate and tetraethylene glycol mono (meth) acrylate. And polypropylene glycol mono (meth) acrylates such as tripropylene glycol mono (meth) acrylate and tetrapropylene glycol mono (meth) acrylate.

Examples of the other copolymerizable monomer include styrene, α-methylstyrene, vinyl acetate and the like.

In the above copolymer, when the amount of the vinyl alcohol or the hydroxyl group-containing monomer is small, the indium oxide powder (b) cannot be dispersed uniformly, the transparency of the coating film is deteriorated, and when the amount is large. Since the chemical resistance of the resulting coating film decreases, it is limited to 2 to 25 mol%, preferably 5 to 20 mol%.

The amount of the other copolymerizable monomer in the above-mentioned copolymer is limited to 0 to 18 mol% because the film-forming property decreases as the amount increases.

The polyvinyl acetal resin is obtained by acetalizing polyvinyl alcohol by condensation reaction with aldehyde. This acetalization is carried out by a precipitation method using an aqueous medium in the presence of an acid catalyst,
A known method such as a dissolution method using a solvent such as alcohol is adopted. It is also possible to use polyvinyl acetate as a raw material and perform saponification and acetalization in parallel to obtain a polyvinyl acetal resin.

The polyvinyl alcohol preferably has an average degree of polymerization of 200 or more. Average degree of polymerization is 2
When it is less than 00, it is difficult to synthesize polyvinyl alcohol and only a solution having a low solution viscosity can be obtained, which is not preferable.

Examples of the aldehyde include formaldehyde, acetaldehyde, propyl aldehyde,
Butyraldehyde, amyl aldehyde, hexyl aldehyde, heptyl aldehyde, octyl aldehyde, 2-
Examples thereof include ethylhexyl aldehyde, decyl aldehyde and cyclohexyl aldehyde, which may be used alone or in combination of two or more.

The polyvinyl acetal resin is
Other than the acetalization site, an acetyl group may be contained in a proportion of 10% by weight or less. Further, the residual hydroxyl group in the polyvinyl acetal resin is insufficient when the dispersion effect of the indium oxide powder (b) is insufficient, and adversely affects the chemical resistance when the residual hydroxyl group increases, so 2-60 mol% is preferable,
It is more preferably 5 to 40 mol%.

The above dispersant (c) in the photocurable conductive coating material
If the amount of (a) decreases, the dispersibility of the indium oxide powder (b) deteriorates and the transparency decreases, and if the amount increases, the hardness, scratch resistance and chemical resistance of the coating film decrease, so the (meth) acrylate compound ( a) 5 to 10 parts by weight
Limited to 0 parts by weight.

The photopolymerization initiator (d) may be any one as long as it has a property of initiating polymerization by active rays such as ultraviolet rays and visible rays.

Among the above photopolymerization initiators (d), those which are activated by ultraviolet rays include, for example, sodium methyl dithiocarbamate sulfide, tetramethyl thiuram monosulfide, diphenyl monosulfide, dibenzothiazoyl monosulfide and disulfide. Sulfides such as; thioxanthone derivatives such as thioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, and 2,4-diethylthioxanthone; (di) azo compounds such as hydrazone, azobisisobutyronitrile, benzenediazonium; benzoin, benzoin Methyl ether, benzoin ethyl ether, benzophenone, dimethylaminobenzophenone, Michler's ketone,
Benzyl anthraquinone, t-butyl anthraquinone,
Aromatic carbonyl compounds such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-aminoanthraquinone and 2-chloroanthraquinone; methyl p-dimethylaminobenzoate, ethyl p-dimethylaminobenzoate,
Dialkylaminobenzoic acid esters such as butyl p-dimethylaminobenzoate and isopropyl p-diethylaminobenzoate; peroxides such as benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide and cumene hydroperoxide; 9-phenylacridine, 9-p-methoxyphenylacridine, 9-
Acridine derivatives such as acetylaminoacridine and benzacridine; 9,10-dimethylbenzphenazine,
Phenazine derivatives such as 9-methylbenzphenazine and 10-methoxybenzphenazine; quinoxaline derivatives such as 6,4 ′, 4 ″ -trimethoxy-2,3-diphenylquinoxaline; 2,4,5-triphenylimidazoyl dimer Etc.

Further, as those which are activated by visible light, for example, 2-nitrofluorene, 2,4,6-triphenylpyrylyl tetrafluoride boron salt, 2,4,6-tris (trichloromethyl)- 1,3,5-triazine,
3,3′-carbonylbiscoumarin, thiomichler ketone and the like can be mentioned.

The photopolymerization initiator (d) is 350 to 40.
It is preferable to have a light absorption region in the range of 0 nm. This is because the indium oxide powder (b) strongly absorbs ultraviolet rays having a wavelength of 350 nm or less, and the coloring becomes strong at a wavelength of 400 nm or more. Further, an amine compound may be added in order to prevent a decrease in sensitivity due to oxygen inhibition of the photopolymerization initiator (d). Such an amine compound is not particularly limited as long as it is a non-volatile compound such as an aliphatic amine or an aromatic amine, and for example, triethanolamine, methyldiethanolamine or the like is used, and further, the dialkylaminobenzoic acid ester is used. A photopolymerization initiator containing an amino group such as Michler's ketone can also be used as the amine compound.

When the amount of the photopolymerization initiator (d) added to the photocurable conductive coating material is small, the photopolymerization reaction is slow and the photopolymerization initiator (d) is used for a long time to obtain a coating film satisfying hardness and scratch resistance. Light irradiation is required, and the heat resistance, weather resistance, etc. of the coating film deteriorates if the number increases, and the conductivity and abrasion resistance are adversely affected. Therefore, the amount is 0.01% based on 100 parts by weight of the (meth) acrylate compound (a). Limited to ~ 20 parts by weight.

An organic solvent may be added to the photocurable conductive coating material in order to adjust the dispersibility of the indium oxide powder (b). The organic solvent used is not particularly limited, but those with a low boiling point and strong volatility change the paint viscosity due to evaporation during coating, and those with a high boiling point require time in the drying step, Boiling point 80
Those at ˜160 ° C. are preferable.

Examples of such organic solvents include methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (methyl cellosolve), diethylene glycol dimethyl ether, butyl acetate, isopropyl acetone, anisole. Etc., and these organic solvents may be used alone or in combination of two or more kinds.

If necessary, various additives such as an ultraviolet absorber, an antioxidant, a thermal polymerization inhibitor, a leveling agent, a surface modifier and a defoaming agent are added to the above photocurable conductive coating material. May be.

Further, a metal salt compound or an organic acid may be added to the photocurable conductive coating material in order to stabilize the fluidity of the coating material, but from the viewpoint of suppressing the release of impurities,
Organic acids having an unsaturated group are particularly preferable. Since the organic acid having such an unsaturated group is incorporated into the crosslinked structure during curing, it is not diffused and released from the coating film after curing.

Examples of the organic acid having an unsaturated group include those containing a carboxyl group such as 2- (meth) acryloyloxyethylsuccinic acid and 2- (meth) acryloyloxyethylphthalic acid; mono [2- (Meta)
Acryloyloxyethyl acid] phosphate, bis [2- (meth) acryloyloxyethyl acid]
Monomers containing a phosphate group such as phosphate and mono [2- (meth) acryloyloxypropyl] acid phosphate; sulfonic acid-containing monomers such as p-styrenesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid. To be

The photocurable conductive coating material of the present invention is (meth)
It is prepared by mixing and dispersing the indium oxide powder (b) in a solution of the acrylate compound (a) and the dispersant (c). The photopolymerization initiator (d) may be added before the indium oxide powder (b) is dispersed and dissolved at the same time as the dispersion, or may be added and dissolved after the indium oxide powder (b) is dispersed. No special device is required to sufficiently disperse the indium oxide powder (b), and, for example, a sand mill, a ball mill, an attritor, a high-speed rotary stirring device, a triple roll, or the like is used.

The photocurable conductive coating material of the present invention prepared by the above method is applied by a general coating method such as a spray method, a bar coating method, a doctor blade method, a roll coating method or a dipping method. A coating film is formed by irradiating with actinic rays such as ultraviolet rays and visible rays to cure the coating. As the coating object of the photocurable conductive coating,
For example, vinyl chloride resin, acrylic resin, ABS resin,
Examples thereof include plastic sheets or plates such as polycarbonate, polyethylene terephthalate, polyether ether ketone, polyphenylene sulfide, polyether sulfone, polysulfone, polyetherimide, and fluororesin; glass plates and the like.

The obtained coating film is preferably surface-finished by buffing. By this surface finish, the transparency of the coating film is improved and the tin oxide powder that easily falls off the surface is removed, so that no dust is generated from the coating film during use, and a member for semiconductor manufacturing that is extremely disliked by dust. Suitable for

The light source for curing the photocurable conductive coating material is not particularly limited, and conventionally known light sources can be used. For example, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp and the like are suitable. Used.

[0048]

EXAMPLES Examples of the present invention will be described below. (Example 1) 100 parts by weight of dipentaerythritol hexaacrylate, 4 parts by weight of diethylthioxanthone and 4 parts by weight of ethyl p-dimethylaminobenzoate were dissolved in 780 parts by weight of ethyl cellosolve and charged into an attritor. While stirring this, tin-doped indium oxide powder having an average particle diameter of 0.1 μm (manufactured by Fuji Titanium Co., Ltd.) 3
00 parts by weight and residual hydroxyl degree 35 mol%, degree of polymerization 240
27 parts by weight of 0 acetoacetal resin was added and dispersed for 8 hours to prepare a photocurable conductive coating material.

The above photocurable conductive coating material was applied on a transparent vinyl chloride resin plate by a bar coater and then at 50 ° C.
And dried with hot air for 10 minutes to form a coating film. This coating,
Ultraviolet rays were irradiated by a high-pressure mercury lamp so that the irradiation amount became 1800 mJ / cm ² and cured. The surface of the obtained cured coating film was buffed with a wool polisher having a diameter of 30 cm and 3000 rpm.

Example 2 100 parts by weight of dipentaerythritol hexaacrylate, 4 parts by weight of diethylthioxanthone and 4 parts by weight of ethyl p-dimethylaminobenzoate were dissolved in 1400 parts by weight of cyclohexanone and charged into an attritor. While stirring this, 400 parts by weight of tin-doped indium oxide powder having an average particle size of 0.1 μm (manufactured by Fuji Titanium Co., Ltd.) and vinyl chloride (90 mol%)-hydroxypropyl acrylate (10 mol%).
26 parts by weight of the copolymer was added and dispersed for 8 hours to prepare a photocurable conductive coating material. From this photocurable conductive paint,
In the same manner as in Example 1, a cured coating film was formed on a transparent vinyl chloride resin plate.

(Example 3) 100 parts by weight of trimethylolpropane triacrylate, diethylthioxanthone 4
Parts by weight and 4 parts by weight of ethyl p-dimethylaminobenzoate were dissolved in a mixed solvent of 300 parts by weight of methyl ethyl ketone and 350 parts by weight of ethyl cellosolve, and charged in an attritor. While stirring this, tin-doped indium oxide powder having an average particle size of 0.1 μm (manufactured by Fuji Titanium Co., Ltd.)
270 parts by weight and methyl methacrylate (84 mol%)
-Hydroxyethyl acrylate (16 mol%) copolymer (30 parts by weight) was added and dispersed for 8 hours to prepare a photocurable conductive coating material. A cured coating film was formed on the transparent vinyl chloride resin plate in the same manner as in Example 1 from this photocurable conductive coating material.

Comparative Example 1 Instead of tin-doped indium oxide powder, antimony oxide-containing tin oxide powder having an average particle size of 0.02 μm (“T-1” manufactured by Mitsubishi Materials Corporation) 3
A photocurable conductive coating material was prepared in the same manner as in Example 1 except that 100 parts by weight was used. A cured coating film was formed on the transparent vinyl chloride resin plate in the same manner as in Example 1 from this photocurable conductive coating material.

Comparative Example 2 Instead of tin-doped indium oxide powder, tin oxide powder containing antimony oxide having an average particle size of 0.02 μm (“T-1” manufactured by Mitsubishi Materials Corporation) 4
A photocurable conductive coating material was prepared in the same manner as in Example 2 except that 100 parts by weight was used. A cured coating film was formed on the transparent vinyl chloride resin plate in the same manner as in Example 1 from this photocurable conductive coating material.

The following performance evaluations were performed on the cured coating films obtained in the above Examples and Comparative Examples, and the results are shown in Table 1. (1) Film thickness A photocurable conductive coating material is applied on a plastic plate by a bar coater and dried with hot air at 50 ° C for 10 minutes to form a coating film, and then a part of the coating film is peeled off and irradiated with ultraviolet rays. To form a cured coating film. Then, the difference in level between the cured coating film forming portion and the cured coating film non-forming portion was measured with a surface shape measuring device (“Dektak3030” manufactured by Sloan Co., Ltd.) and used as the thickness of the cured coating film. (2) Surface resistivity The surface resistivity was measured according to ASTM D257. (3) Total light transmittance and haze Total light transmittance and haze were measured according to ASTM D1003. (4) Scratch resistance test After performing a sliding test 100 times with steel wool (# 0000) having a load of 1 kg / cm ² , the cured coating film was evaluated according to the following evaluation criteria. 1: Many scratches were observed. 2: A considerable number of scratches were recognized. 3: 2-3 scratches were recognized. 4: A slight scratch was recognized. 5: No scratch was observed.

[0055]

[Table 1]

[0056]

The composition of the photocurable conductive coating material of the present invention is
As described above, it is easily cured by ultraviolet rays or visible rays to form a coating film having excellent transparency and scratch resistance. In particular, the transparency and scratch resistance are excellent even for substrates with low surface hardness where it was difficult to achieve both transparency and scratch resistance due to their superior transparency compared to conventional transparent conductive coating films. Can be given at the same time.

Claims (1)

[Claims] 1. (a) 100 parts by weight of a (meth) acrylate compound having at least two or more (meth) acryloyl groups in the molecule, (b) an average particle diameter of 0.01 to 0.4 μm.
200 to 500 parts by weight of tin-doped indium oxide powder, (c) 5 to 100 parts by weight of dispersant, and (d) 0.01 to 20 parts by weight of photopolymerization initiator. Conductive paint.