JPH0425981B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a coating composition that is easily cured by radiation such as ultraviolet rays and electron beams, and is capable of forming a coating film having excellent scratch resistance, conductivity, and transparency. (Prior Art) Semiconductor wafer storage containers, electronic/electrical parts, floor materials and wall materials of semiconductor manufacturing factories, etc., need to have an antistatic effect depending on their use. To this end, conventionally these parts were coated with paint containing carbon powder or metal powder, or
Alternatively, carbon powder, carbon fiber, metal fiber, etc. are kneaded into resin and molded. However, in these conventional methods, the coating film and molded article themselves are colored and are therefore opaque, making it impossible to see through the contents. Therefore, it is not possible to use a window as a portion that requires antistatic protection. Japanese Unexamined Patent Publication No. 57-85866 discloses a paint containing a conductive paint containing tin oxide as a main component in a paint binder. Although this paint can form a coating film that is transparent and has an antistatic function, since the paint binder is a thermoplastic resin, the resulting coating film generally cannot exhibit scratch resistance or solvent resistance. Furthermore, metal powder such as tin oxide generally has a higher specific gravity than a paint binder, and therefore is difficult to uniformly disperse. (Problems to be Solved by the Invention) The object of the present invention is to provide steel wool that is easily cured by radiation such as ultraviolet rays and electron beams, has excellent scratch resistance and stain resistance, and has excellent conductivity and transparency. It is an object of the present invention to provide a coating composition that can form a coating film with a high temperature. (Means for Solving the Problem) The gist of the present invention is to provide a paint binder whose main component is one or more (meth)acrylic oligomers having at least two or more acryloyl groups or methacryloyl groups in the molecule. , a conductive powder whose main component is tin oxide and whose particle size is 0.2 μm or less, and the general formula (1) (In the formula, R ₁ is hydrogen or a methyl group, R ₂ is an alkyl group having 1 to 8 carbon atoms) A monomer represented by the general formula (2) (In the formula, R ₃ and R ₄ are hydrogen or methyl groups, and n is 1 to
10) and a copolymer whose main component is a (meth)acrylic monomer having a fluorine atom in the molecule. The present invention relates to a compound having at least two or more acroyl groups or methacryloyl groups in the molecule (meth)
When acrylic oligomer is photocured, it becomes highly crosslinked, improving the scratch resistance and hardness of the resulting coating film.By adding a conductive powder whose main component is tin oxide, it maintains sufficient conductivity while maintaining excellent conductivity. The main components are (meth)acrylate monomers, (meth)acrylate monomers having a hydroxyl group in the molecule, and (meth)acrylic monomers having a fluorine atom in the molecule. Based on the knowledge that adding a copolymer prevents recrystallization of the conductive powder, significantly improves the transparency of the resulting coating film, and further improves the stain resistance of the coating film from ink, etc. completed. The composition of the present invention contains a (meth)acrylic oligomer having two or more acryloyl or methacryloyl groups as a paint binder.
This (meth)acrylic oligomer is cured into a highly crosslinked structure. Examples of the (meth)acrylic oligomer include bifunctional acrylates or methacrylates such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, tetraethylene glycol diacrylate, and tetraethylene glycol dimethacrylate. In addition, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, glycerol triacrylate, glycerol trimethacrylate, pentaerythritol triacrylate,
Examples include trifunctional or higher functional acrylates or methacrylates such as pentaerythritol trimethacrylate, tris(2-hydroxyethyl)-isocyanurate acrylate, and tris(2-hydroxyethyl)-isocyanurate methacrylate. A reactive monofunctional acrylate or methacrylate may be included for the purpose of lowering the viscosity of the paint. So-called urethane acrylates, in which (meth)-acrylic oligomers have urethane bonds in their molecular skeletons, can also be suitably used. To prepare such a urethane oligomer having an acryloyl group or a methacryloyl group at the end of the molecule, one molecule of polyol is polymerized with a compound having two or more isocyanate groups, and an acrylate having active hydrogen is added to the isocyanate group at the end of the molecule. Alternatively, it can be carried out by using methacrylate. Examples of the polyols include ethylene glycol, 1,3-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1 , 5-heptanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol and the like. Other examples include polyethylene glycol, polypropylene glycol, and polyoxytetramethylene glycol. Furthermore, there are also condensed polyester glycols of adipic acid and ethylene glycol, adipic acid and propanediol, adipic acid and neopentyl glycol, adipic acid and butanediol, or adipic acid and hexanediol. Ring-opened ε-caprolactone polymers can also be used as polyols.
Examples of compounds having two or more isocyanates in one molecule include hexamethylene diisocyanate, methylene diphenyl diisocyanate,
Examples include toluene diisocyanate, xylene diisocyanate, and methylene dicyclohexyl diisocyanate. Examples of active hydrogen-containing acrylates or methacrylates include 2-
Examples include hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and acrylic acid. The coating composition of the present invention contains one or more compounds of these difunctional or higher-functional (meth)acrylic oligomers as a coating binder. The conductive powder containing tin oxide as a main component contained in the coating composition of the present invention has an average particle size of
It is 0.2 μm or less. If it exceeds 0.2 μm, visible light is scattered, resulting in poor transparency of the resulting coating film. At the same time, it also scatters ultraviolet rays, which reduces the photocurability of the paint binder and sometimes does not cure it properly. Its content is 50 to 400 parts by weight per 100 parts by weight of the organic binder component to ensure transparency and conductivity of the coating film.
It is desirable to include it in parts by weight. If the amount of this conductive powder is less than 50 parts by weight, even if the degree of dispersion is sufficient, the resulting coating film will not exhibit sufficient conductivity, and the antistatic effect, which is one of the purposes of the present invention, will not be achieved. I can't wait. If it exceeds 400 parts by weight, it will become overcrowded, resulting in poor dispersion of the fine powder, resulting in a loss of transparency of the coating film and a decrease in scratch resistance. In the present invention, in order to improve the dispersibility of the conductive powder, improve the transparency of the coating film, further improve the scratch resistance with steel wool, and greatly improve the stain resistance with ink etc., General formula (1) (In the formula, R ₁ is hydrogen or a methyl group, R ₂ is an alkyl group having 1 to 8 carbon atoms) A monomer represented by the general formula (2) (In the formula, R ₃ and R ₄ are hydrogen or methyl groups, and n is 1 to
It contains a copolymer whose main components are a monomer represented by (an integer of 10) and a (meth)acrylic monomer having a fluorine atom in the molecule. Examples of the monomer of general formula (1) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, Examples include octyl (meth)acrylate. Examples of the monomer of general formula (2) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate (the number of ethylene is 2 to 10), polypropylene Glycol mono(meth)acrylate (number of propylene is 2~
10) etc. The components of the monomer of general formula (2) are 2-
It is preferable to use it in a range of 30 mol%; if it is less than 2 mol%, sufficient effects will not be exhibited, and if it exceeds 30 mol%, the moisture resistance of the system will deteriorate, which is not preferred. Examples of (meth)acrylic monomers containing fluorine atoms in the molecule include monofluoroethyl (meth)acrylate, difluoroethyl (meth)acrylate, and pentafluoropropyl (meth)acrylate. Can be mentioned. This (meth)acrylic monomer component is 10 to 60 mol% in the copolymer.
If it is less than 10 mol%, sufficient effects such as dispersion effect, stain resistance, and surface smoothness imparting will not be exhibited, and if it exceeds 60 mol%, the monomer of general formula (1) will be used. It is difficult to copolymerize with the monomer of general formula (2) and has poor solubility in various organic solvents, making it undesirable as a paint binder component. The content of this copolymer needs to be in the range of 2 to 70% by weight, with a particularly preferable range of 5 to 50% by weight based on the total amount of the organic binder. If the content is less than 2% by weight, the conductive powder will be insufficiently dispersed and transparency will decrease. If it exceeds 70% by weight, the amount of crosslinking component will decrease and the desired abrasion resistance will not be achieved. A photosensitizer is selectively added for the purpose of improving the photocurability of the paint binder. Examples of the photosensitizer include benzoin, benzyl, benzoin isopropyl ether, benzoin isomethyl ether, α-methylbenzoin, α-phenylbenzoinbenzyl, diacetylmethylanthraquinone, chloranthraquinone, benzophenone, benzophenone, anthraquinone, mifilar ketone, Carbonyl compounds such as 4,4'-bis(N,N'-diethylamino)-benzophenone and acetophenone, sulfur compounds such as diphenyl sulfide, diphenyl disulfide, and dithiocarbamates, α-chloromethylnaphthalene, anthracene, etc. naphthalene, anthracene compounds,
Examples include halogenated hydrocarbons such as dimethyl tetrachlorophthalate and hexachlorobutadiene, metal salts such as uranyl sulfate, iron chloride, and silver chloride, and pigments such as acriflavin, fluorescein, riboflavin, and rhodamine B. The amount of these sensitizers added is preferably 0.01% by weight or more based on the photocurable oligomer. Amines can be used as auxiliaries for the photocuring reaction. Examples of amines include triethylamine, tributylamine, diethylaminoethyl methacrylate, and the like. The conductive coating composition of the present invention is prepared by adding the coating binder, the copolymer, and a powder containing tin oxide as main components to an organic solvent and mixing them.
In order to sufficiently disperse the powder in the coating material, equipment commonly used for dispersing and compounding coating materials, such as a sand mill, a ball mill, a high-speed rotating stirrer, a triple roll, etc., may be used. (Action of the invention) The conductive coating composition of the present invention prepared as described above should be applied by a general coating method such as a spray method, a roll coater method, a barcoal method, a doctor blade method, or a dipping method. It is applied to an object, for example a synthetic resin sheet or plate. Examples of the material for this synthetic resin sheet or plate include polyvinyl chloride, polyethylene terephthalate, polycarbonate, poly(meth)acrylate, acrylonitrile-butadiene-styrene copolymer, polyethylene, and polypropylene. After coating, a transparent conductive plate or sheet with desired scratch resistance can be obtained by irradiating it with ultraviolet rays or radiation (gamma rays, electron beams). Since these plates or sheets are hardly charged, they are suitably used as materials for electronic devices or materials for electronic device manufacturing factories that require functions such as preventing dust accumulation, preventing electrostatic damage, and preventing electrostatic malfunctions. (Example) The present invention will be explained below with reference to Examples. Example 1 (A) Synthesis of reactive binder: 530 g of ε-caprolactone ring-opening polymer (average molecular weight 530: Daicel Plascel 205) was charged into a reactor equipped with a cooling tube, a stirrer, and a roll, and nitrogen gas was added. The temperature was raised to 80°C while flowing water. To this was added 1 g of dibutyltin laurate as a urethane production catalyst. 524 g of 4,4'-diphenylmethane diisocyanate was placed in the dropping funnel and added dropwise over 1 hour, and stirring was continued at 80°C for 1 hour. Next, the polymerization inhibitor hydroquinone is added to the reaction system.
After adding 1 g, 232 g of 2-hydroxyethyl acrylate was added and stirring was continued for 2 hours. The average molecular weight of the obtained oligomer was 1500. (B) Synthesis of dispersibility-imparting copolymer: In a reactor equipped with a cooling tube, a stirrer, and a dropping funnel, add 400 g of methyl ethyl ketone, 200 g of methyl methacrylate,
2-hydroxyethyl methacrylate 100g,
200 g of trifluoroethyl methacrylate was charged, and the temperature was raised to 80°C under a nitrogen stream. On the other hand, 1.0 g of azobisisobutyronitrile as a polymerization initiator was dissolved in 80 g of methyl ethyl ketone and charged into a dropping funnel. After the temperature of the liquid in the reaction vessel rose to 80°C, the polymerization initiator solution was added dropwise from the dropping funnel over a period of 4 hours.
Thereafter, 1.5 g of azoisobutyronitrile was dissolved in 20 g of methyl ethyl ketone and added into the reactor, and the reaction was continued for an additional 4 hours to synthesize a dispersibility-imparting copolymer solution B. (C) Preparation of paint: 60 g of the dispersibility-imparting copolymer solution prepared in section (B) above, 230 g of tin oxide containing antimony trioxide with an average particle size of 0.2 μm or less, and 540 g of methyl ethyl ketone were placed in a ball mill and dispersed over 24 hours. I let it happen. Next, 20 g of the reactive oligomer synthesized in section (A) above, 30 g of trimethylolpropane trimethacrylate, 20 g of diethylene glycol dimethacrylate, 20 g of pentaerythritol tetraacrylate, 300 g of ethyl cellosolve, 14 g of benzophenone, and 2.9 g of Mifilar ketone were added to the mixture. Continue stirring for an hour,
The paint was made. (D) Preparation and performance evaluation of paint: The above paint was applied onto a transparent acrylic plate (Acrylite manufactured by Mitsubishi Rayon Co., Ltd., thickness 3 mm) to a film thickness of 2 μm (when dry). After drying the solvent at 50° C. for 5 minutes, ultraviolet rays were irradiated for 15 minutes from a distance of 25 cm using a high-pressure mercury lamp (output 5.6 KW, effective lamp length 70 cm). The surface resistivity, total light transmittance, haze value, and pencil hardness of the resulting coating film were measured, as well as a steel wool scratch test and stain resistance. The results are shown in Table 1. Incidentally, the surface resistivity was measured by a test method based on ASTM-D-257, the total light transmittance and haze value by ASTM-D-1003, and the pencil hardness by a test method based on JIS K-5400. In the steel wool abrasion test, the material was rubbed 500 times under a load of 500 g per cm ² , and then judged based on the presence or absence of scratches. For stain resistance, each sample was marked with magic ink, Creon, or lipstick, and after one week, it was wiped with methanol to determine the presence or absence of residual contamination. Example 2 Synthesis of reactive binder: Same as Section (A) of Example 1. Synthesis of dispersibility-imparting copolymer: Same as Section (B) of Example 1. Preparation of paint: 96 g of the dispersibility-imparting copolymer solution prepared in Section (B) of Example 1, 230 g of tin oxide containing antimony trioxide with an average particle size of 0.2 μm or less, and 540 g of methyl ethyl ketone were placed in a ball mill and dispersed over 24 hours. I let it happen. Next, 20 g of the reactive oligomer synthesized in Section (A) of Example 1, 22 g of trimethylolpropane trimethacrylate, 15 g of diethylene glycol dimethacrylate, 15 g of pentaerythritol tetraacrylate, and ethyl cellosolve.
300g, Benzophenone 14g, Mifilar Ketone
2.9g was added and stirring was continued for an additional 24 hours to prepare a paint. Preparation of coating film and performance evaluation: Same as Example 1 (D) except that the above coating material was used. Example 3 Synthesis of reactive binder: Same as Example 1, section (A). Synthesis of dispersibility-imparting copolymer: In the same manner as in Section (B) of Example 1, the monomer composition was changed to 300 g of methyl methacrylate, 80 g of 2-hydroxyethyl methacrylate, and trifluoroethyl methacrylate.
The composition was changed to 120 g, and a dispersibility-imparting copolymer (B') was synthesized. Preparation of paint: 96 g of the above dispersibility-imparting copolymer (B') solution, 230 g of tin oxide containing antimony trioxide with an average particle size of 0.2 μm or less, and 540 g of methyl ethyl ketone were charged into a Pall mill and dispersed over 24 hours. Next, 20 g of the reactive oligomer synthesized in Section (A) of Example 1, 22 g of trimethylolpropane trimethacrylate, 15 g of diethylene glycol dimethacrylate, 15 g of pentaerythritol tetraacrylate, 300 g of ethylene cellosolve, 14 g of benzophenone, and 2.9 g of Mifilar ketone were added to this. After preparation, stirring was continued for another 24 hours to produce a paint. Preparation of coating film and performance evaluation: Same as Example 1 (D) except that the above coating material was used. Example 4 Synthesis of reactive binder: Same as Example 1, section (A). Synthesis of dispersibility-imparting copolymer: The monomer composition was changed to methyl methacrylate using the method described in Example 1 (B).
260g, isobutyl methacrylate 40g, 2-hydroxypropyl acrylate 100g, and trifluoroethyl acrylate 100g to synthesize a dispersion-imparting copolymer (B''). Preparation of paint: the above dispersion-imparting copolymer 60 g of solution (B'') and 540 g of methyl ethyl ketone were placed in a ball mill and dispersed over 24 hours. Next, 20 g of the reactive oligomer synthesized in Section (A) of Example 1,
Trimethylolpropane trimethacrylate
30g, diethylene glycol dimethacrylate
20g, pentaerythritol tetraacrylate
20g, ethylene cellosolve 300g, benzophenone
14g, Mihuira Ketone 2.9g, and 24g
Stirring was continued for a period of time to prepare a paint. Preparation of coating film and evaluation of performance: Same as Section (D) of Example 1 except that the above coating material was used. Comparative Example 1 Synthesis of reactive binder: Same as Section (A) of Example 1. Synthesis of dispersibility-imparting copolymer: The monomer composition was changed to methyl methacrylate using the method described in Example 1 (B).
400g, 2-hydroxyethyl methacrylate
The amount was changed to 100 g, and a dispersibility-imparting copolymer (B) was synthesized. Preparation of paint: the above dispersibility-imparting copolymer (B)
60 g of the solution and 540 g of methyl ethyl ketone were placed in a ball mill and dispersed over 24 hours. Next, the reactive oligomer synthesized in Section (A) of Example 1 was added to this.
20g, trimethylolpropane trimethacrylate 30g, diethylene glycol dimethacrylate
20g, pentaerythritol tetraacrylate
20g, ethylene cellosolve 300g, benzophenone
14g, Mihuira Ketone 2.9g, and 24g
Stirring was continued for a period of time to prepare a paint. Preparation of coating film and performance evaluation: Same as Example 1 (D) except that the above coating material was used. Comparative Example 2 Synthesis of reactive binder: Same as Section (A) of Example 1. Preparation of paint: In a ball mill, add 200 g of methyl ethyl ketone, 30 g of the reactive oligomer synthesized in Section (A) of Example 1, 40 g of trimethylolpropane trimethacrylate, 25 g of diethylene glycol dimethacrylate, 25 g of pentaerythritol tetraacrylate, 150 g of ethylene cellosolve, and 14 g of benzophenone. , prepare 2.9g of Mifilar Ketone,
Stirring was continued for 24 hours to prepare a paint. Preparation of coating film and performance evaluation: Same as Example 1 (D) except that the above coating material was used.

[Table] (Effects of the Invention) The conductive coating composition of the present invention has a (meth)acrylic oligomer having at least two or more acroyl groups or methacryloyl groups in the molecule. When cured, etc., it becomes highly cross-linked, improving the scratch resistance and hardness of the resulting coating film.Since it contains conductive powder whose main component is tin oxide, it maintains more sufficient conductivity and has excellent properties. Transparency can be obtained, and the above-mentioned (meth)acrylate monomers, (meth)acrylate monomers having a hydroxyl group in the molecule, and (meth)acrylic monomers having a fluorine atom in the molecule are mainly used. Contains a copolymer as a component, which prevents recrystallization of the conductive powder, significantly improves the transparency of the resulting coating film, and furthermore provides excellent scratch resistance and stain resistance from ink, etc. There is.

Claims (1)

[Claims] 1. A paint binder whose main component is one or more (meth)acrylic oligomers having at least two or more acryloyl or methacryloyl groups in the molecule, and a paint binder whose main component is tin oxide. Conductive powder with a particle size of 0.2 μm or less and general formula (1) (In the formula, R ₁ is hydrogen or a methyl group, R ₂ is an alkyl group having 1 to 8 carbon atoms), a monomer represented by the general formula (2) (In the formula, R ₃ and R ₄ are hydrogen or methyl groups, and n is 1 to
An electrically conductive coating composition containing a monomer represented by (an integer of 10) and a copolymer whose main component is a (meth)acrylic monomer having a fluorine atom in the molecule.