JPH0519463B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is directed to a conductive plastic sheet, film or plate, in particular a transparent plastic substrate, in which a conductive coating film is formed, and the coating film has excellent transparency, hardness, strength and This invention relates to a method for producing conductive plastic sheets, films or plates that are scratch resistant. (Prior Art) Semiconductor wafer storage containers, electronic/electrical components, 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 the 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. JP-A-57-85866 discloses a paint containing a paint binder containing conductive fine powder containing tin oxide as a main component. This paint can form a film that is transparent and has an antistatic function, but since the paint binder is a thermoplastic resin, the resulting paint film generally cannot exhibit not only scratch resistance but also solvent resistance. . (Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional drawbacks, and its purpose is to provide a conductive plastic sheet with excellent hardness, strength, and scratch resistance;
The purpose is to provide films or plates.
Another object of the present invention is to provide a conductive plastic sheet, film or plate having high transparency, hardness and scratch resistance and having a coating layer of a conductive paint on the surface which can be easily photocured or radiation cured. It's about doing. (Means for Solving the Problems) The method for producing a conductive plastic sheet, film or plate of the present invention is characterized in that (a) the main component is an oligomer having at least two radically reactive unsaturated groups in the molecule; Binder; and average particle size
A step of obtaining a transparent conductive paint containing a conductive powder mainly composed of tin oxide with a size of 0.2 μm or less, (b) forming a coating layer of the transparent conductive paint on a plastic film with low adhesion to the coating film; (c) forming an adhesive resin composition layer containing an oligomer having at least two radically reactive unsaturated groups in the molecule on a transparent plastic substrate; and (d) combining the first laminate and the second laminate with the coating layer surface of the first laminate and the adhesive resin composition layer surface of the second laminate. and (e) irradiating the laminate obtained in step (d) with ultraviolet rays or radiation, thereby achieving the above object. According to the present invention, first, a coating layer of a transparent conductive paint is formed on a plastic film, and the binder of the transparent conductive paint has at least two molecules in its molecule.
The main component is an oligomer having radically reactive unsaturated groups. This oligomer has the property of being highly crosslinked and cured by light or radiation.
Such oligomers include, for example, (meth)acrylic oligomers. It has two or more acryloyl or methacryloyl groups.
This (meth)acrylic oligomer includes ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate, tetraethylene glycol diacrylate,
Difunctional acrylates or methacrylates such as tetraethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, glycerol triacrylate, glycerol trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, tris(2- hydroxyethyl) isocyanurate acrylate, tris(2
There are also trifunctional or higher functional acrylates or methacrylates such as -hydroxyethyl) isocyanurate ester methacrylate. Reactive monofunctional acrylates or methacrylates can be added when it is desired to reduce the viscosity of the coating or to obtain desired properties of the coating. When a (meth)acrylic oligomer having a urethane bond in its molecular skeleton is used, the abrasion resistance and scratch resistance of the coating film are improved. To prepare such a urethane oligomer having an acryloyl group or a methacryloyl group at the end of the molecule, a polyol and a compound having two or more isocyanate groups per molecule are polymerized, and the isocyanate group at the end of the molecule is
This can be carried out by using acrylate or methacrylate containing active hydrogen. Examples of the above polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,2-butanediol, 1.
3-butanediol, 1,4-butanediol,
There are short chain diols such as 2,3-butanediol, 1,5-heptanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and trimethylolpropane. There are also polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, etc. 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, and adipic acid and hexanediol. Ring-opened ε-caprolactone polymers can also be used as polyols.
Examples of compounds having two or more isocyanate groups in one molecule include hexamethylene diisocyanate, methylene diphenyl isocyanate, toluene diisocyanate, xylene diisocyanate, and methylene dicyclohexyl diisocyanate. Examples of active hydrogen-containing acrylates or methacrylates include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate,
Examples include acrylic acid. As described above, the transparent conductive paint used in the method of the present invention contains one or two types of oligomers having at least two radically reactive unsaturated groups, preferably difunctional or higher-functional (meth)acrylic oligomers, as a binder. The above is included. The conductive powder contained in the transparent conductive paint contains tin oxide as a main component, and its average particle size is 0.2 μm or less. When the average particle size exceeds 0.2 μm, visible light is scattered, resulting in poor transparency of the resulting coating film. The content thereof is 100 to 350 parts by weight per 100 parts by weight of the paint binder in order to ensure transparency and conductivity of the coating film. If the amount of this conductive powder is less than 100 parts by weight, even if the degree of dispersion is sufficient, the resulting coating film will not exhibit sufficient conductivity, and therefore the antistatic effect, which is one of the purposes of the present invention, will be reduced. cannot be fully demonstrated. If it exceeds 350 parts by weight, the powder becomes overcrowded, resulting in poor dispersion of the powder, and as a result, the transparency of the resulting coating film is impaired. In the present invention, in order to enhance the dispersion of the conductive powder, methyl methacrylate is used as a dispersant and the general formula: (R ₁ = H, CH ₃ ; R ₂ = H, CH ₃ ; n = 1 to 10)
A copolymer with the monomer represented by can be added as necessary. By adding such a methacrylic copolymer having a hydroxyl group, the resulting coating film maintains electrical conductivity, has excellent transparency, and also improves its scratch resistance. In addition, it has excellent settling and redispersibility of paint. The amount of copolymer necessary to obtain such excellent effects is preferably 0.1 parts by weight or more based on 100 parts by weight of the binder. For the purpose of improving the photocurability of the paint binder, a photosensitizer is appropriately added as necessary. Examples of the photosensitizer include benzoin, benzyl, benzoin isopropyl ether, benzoin isomethyl ether, α-methylbenzoin,
α-phenylbenzoin Carbonyl compounds such as benzyl, diacetylmethylanthraquinone, chloranthraquinone, benzophenone, anthraquinone, mifilar ketone, 4,4′-bis(N・N′-diethylamino)benzophenone, acetophenone; diphenyl sulfide, diphenyl Sulfur compounds such as disulfides and dithiocarbamates; naphthalene and anthracene compounds such as α-chloromethylnaphthalene and anthracene; halogenated hydrocarbons such as dimethyl tetrachlorophthalate and hexachlorobutadiene; uranyl sulfate,
Metal salts such as iron chloride and silver chloride; pigments such as acriflavin, fluorescein, riboflavin, and rhodamine B; and the like. The amount of these sensitizers added is preferably 0.01 to the oligomer.
% by weight or more. For example, amines can be used as an auxiliary agent for the photocuring reaction. Examples of amines include triethylamine, tributylamine, and diethylamine ethyl methacrylate. The transparent conductive paint used in the method of the present invention is prepared by adding the binder, the conductive powder containing tin oxide as a main component, and, if necessary, the dispersant, photosensitizer, etc. to an organic solvent and mixing them. can get. In order to sufficiently disperse the conductive 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 stirring device, and a three-roll device, can be used. In order to further enhance the dispersion of this fine powder, dispersion aids such as silane coupling agents, titanate coupling agents, surfactants, oleic acid, and lecithin may also be used. As shown in FIG. 1a, the transparent conductive paint thus obtained is a plastic film 1 with a smooth surface and low adhesion to the paint film.
1 to a thickness of 1 to 2 μm.
A transparent conductive coating layer 12 is formed. A first laminate 1 is formed of the plastic film 11 and the transparent conductive coating layer 12. The material of the plastic film 11 includes, for example, polyester,
Polyethylene and polypropylene are used. It is recommended that the surface of the plastic film 11 to which the paint is applied be subjected to mold release treatment in advance. Next, a transparent plastic base material 21 such as a plastic plate, a plastic sheet, or a plastic film is prepared, and as shown in FIG. A composition layer 22 is formed. A second laminate 2 is formed of the plastic base material 21 and the adhesive resin composition layer 22. Acrylic, vinyl chloride, polycarbonate, etc. are used as the material for the plastic base material 21. Like the transparent conductive paint, the adhesive resin composition also contains an oligomer having at least two radically reactive unsaturated groups in the molecule. This oligomer is preferably of the same type as the oligomer contained in the transparent conductive paint used when preparing the first laminate 1 described above. The adhesive resin composition is preferably a mixture of the above oligomer and polymethyl methacrylate. Since such an adhesive resin composition has appropriate adhesiveness and viscosity, it adheres well to the coating layer of the first laminate 1 in the process of forming a laminate described later, and has a low viscosity. There is no leakage. The adhesive resin composition may contain, if necessary,
A photosensitizer may also be added. The photosensitizer is
The same type of material contained in transparent conductive paints can be used. The adhesive resin composition layer 22 is formed on the plastic base material 21 to have a thickness of 4 μm or more. As shown in FIG. The adhesive resin composition layers 22 are laminated so as to correspond to each other, and bonded using a laminator or the like while heating if necessary. When the laminate thus obtained is irradiated with ultraviolet rays or radiation, the crosslinking reaction of the oligomers contained in the transparent conductive coating and the adhesive resin composition layer progresses and is cured. When the plastic film 11 of the laminate is peeled off, the first
The desired plastic sheet, film or plate having a transparent conductive coating layer 12 on its surface is obtained, as shown in Figure d. (Function) The surface of the transparent conductive coating layer of the plastic sheet, film or plate obtained by the method of the present invention is extremely smooth and has minute irregularities because the surface of the plastic film used for the first laminate is smooth. is virtually non-existent. Therefore, it has a high haze value and excellent scratch resistance. Even if a transparent conductive paint is applied directly onto a plastic substrate, a plastic sheet, film or plate with relatively high hardness and excellent transparency can be obtained. However, since fine irregularities occur on the surface of the coating layer, transmitted light is scattered and the haze value becomes slightly low. Scratch resistance is also slightly inferior due to the fine irregularities on the surface. The plastic sheet, film or plate obtained by the method of the present invention has a form in which a cured heat-adhesive resin composition layer and a cured transparent conductive coating layer are sequentially laminated on a plastic base material, so that it is transparent. Even if the conductive coating layer is thin, a highly hard adhesive resin composition layer is present as a primer layer, resulting in a transparent plastic sheet, film or plate having excellent hardness, strength and scratch resistance. Since the transparent conductive coating layer may be thin, only a small amount of relatively expensive conductive powder is required. (Example) The present invention will be described below with reference to preferred examples. Example 1 (A) Synthesis of oligomer having urethane bond: 530 g of ε-caprolactone ring-opening polymer (average molecular weight 530: Daicel Plaxel 205) was placed in a separable flask reactor equipped with a cooling tube, a stirrer, and a dropping funnel. While preparing and flowing nitrogen gas
The temperature was raised to 80°C. To this was added 1 g of dibutyltin laurate as a urethane production catalyst.
4,4'-diphenylmethane diisocyanate
524 g was placed in a dropping funnel and added dropwise over 1 hour, and stirring was continued at 80°C for another 1 hour. Next, 1 g of hydroquinone was added as a polymerization inhibitor to this reaction system, and then 232 g of 2-hydroxyethyl acrylate was added, and stirring was continued for 1 hour.
The weight average molecular weight of the obtained oligomer was 1000. (B) Hydroxyl group-containing methacrylic copolymer (dispersant)
Synthesis of: Toluene 130 in a separable flask reactor equipped with a cooling tube, stirrer and dropping funnel.
I prepared g. This was heated to 110°C under a nitrogen stream. On the other hand, methyl methacrylate 115
g, 2-hydroxyethyl methacrylate 35
g, and 0.7 g of azobisisobutyronitrile as a polymerization initiator was prepared, and this was dropped into the reactor from the dropping funnel over 2 hours to polymerize. Then, the temperature inside the reactor was increased to 90
℃. Next, 2 g of azobisisobutyronitrile was dissolved in 20 g of toluene, and this was dropped into the reactor from the dropping funnel over 2 hours. After the dropwise addition, polymerization was continued at 90°C for another 2 hours. The weight average molecular weight of the obtained hydroxyl group-containing methacrylic copolymer was 42,000. (C) Preparation of transparent conductive paint: 84 g of the hydroxyl group-containing methacrylic copolymer solution prepared in section (B), and tin oxide containing antimony trioxide with an average particle size of 0.2 μm or less.
280 g and 400 g of methyl ethyl ketone were placed in a ball mill and dispersed for 24 hours. Next, 20 g of the oligomer having a urethane bond prepared in section (A), 20 g of trimethylolpropane trimethacrylate, 10 g of diethylene glycol dimethacrylate, 38 g of pentaerythritol tetraacrylate, 14 g of benzophenone, and 2.9 g of Mifilar ketone were added thereto, and for another 24 hours. Stirring was continued to obtain a paint. (D) Preparation and performance evaluation of conductive plastic plate: A transparent oriented polypropylene (OPP) film with a thickness of 60 μm was coated with the transparent conductive paint prepared in section (C) so that the thickness after drying was 1 μm. The solvent was dried and removed at 50°C to obtain a first laminate. Polymethyl methacrylate 30 with a molecular weight of 100,000
g, 20 g of the oligomer having a urethane bond prepared in section (A), 20 g of trimethylolpropane trimethacrylate, 10 g of diethylene glycol dimethacrylate, 38 g of pentaerythritol tetraacrylate, and 10 g of Darocyur (trade name) as a photosensitizer, and 60 g of methyl ethyl ketone.
g and 10 g of ethyl cellosolve. This solution was coated on a transparent acrylic plate to a thickness of 10 μm after drying and dried to obtain a second laminate. They were laminated so that the adhesive resin surface of the second laminate and the transparent conductive coating surface of the first laminate were in contact with each other, and they were bonded together at room temperature using a laminator. of this laminate
A high-pressure mercury lamp (output
The OPP film was peeled off after irradiation for 10 minutes from a distance of 25 cm using 5.6 kW (effective lamp length 170 cm). The surface specific resistivity, total light transmittance and haze value of the coating film on the transparent acrylic plate of the obtained conductive plastic plate were measured. Furthermore, a scratch resistance test using steel wool was conducted. The respective results are shown in the table below. The surface resistivity is
ASTM-D-257, total light transmittance and haze value are
Measured using a test method based on ASTM-D-1003. In the abrasion resistance test using steel wool, judgment was made based on the presence or absence of scratches after rubbing 500 times under a load of 500 g per cm ² . The mark ○ indicates that the surface of the coating layer is not scratched. Example 2 (A) Synthesis of oligomer having urethane bond: Same as Example 1 (A). (B) Synthesis of hydroxyl group-containing methacrylic copolymer: Same as Example 1 (B). (C) Preparation of transparent conductive paint: Hydroxyl group-containing methacrylic copolymer solution 60 prepared in section (B) of this example
g, 270 g of tin oxide containing antimony trioxide with an average particle size of 0.2 μm or less and 400 g of methyl ethyl ketone.
was placed in a ball mill and dispersed over 24 hours. To this, 30 g of the oligomer having a urethane bond obtained in Section (A) of this Example; 20 g of trimethylolpropane trimethacrylate; 10 g of tetraethylene glycol dimethacrylate; 30 g of dipentaerythritol hexaacrylate; 14 g of benzophenone and 3 g of Mifilar ketone as photoinitiators. ; Ethyl cellosolve was further stirred for 24 hours to obtain a paint. (D) Preparation and performance evaluation of conductive plastic plate: A first laminate was obtained according to Example 1 (D). 30g of polymethyl methacrylate with a molecular weight of 100,000,
30 g of the oligomer having a urethane bond prepared in Example (A), 20 g of trimethylolpropane triacrylate, 10 g of tetraethylene glycol dimethacrylate, 30 g of dipentaerythritol hexaacrylate, and 7 g of Darocyur 1173 (trade name) as a photosensitizer. 60g of methyl ethyl ketone
and 60 g of ethyl cellosolve. This solution was coated and dried on a transparent acrylic plate so that the thickness after drying was 10 μm to obtain a second laminate. A plastic plate was obtained according to Example 1 using the obtained first laminate and second laminate.
The performance of the coating surface of the plastic plate was evaluated in the same manner as in Example 1. The results are shown in the table below. Example 3 The same as Example 2 except that a transparent vinyl chloride plate was used instead of a transparent acrylic plate as the plastic base material.

[Table] (Effects of the Invention) According to the method of the present invention, a conductive plastic sheet, film or plate which is extremely excellent in not only conductivity but also transparency, hardness, strength and abrasion resistance can be obtained. Since there are virtually no fine irregularities on the surface of the plastic sheet, film or plate, the haze value is low and the transparency will not be impaired by fine scratches even when used over a long period of time. Even if the transparent conductive coating layer located on the outermost surface is relatively thin, the adhesive resin composition exists as a primer layer on the inside, so the plastic sheet, film or plate of the present invention has sufficient transparency, hardness and It can have strength and scratch resistance. Since the transparent conductive coating layer is thin, only a small amount of expensive conductive powder is required, and plastic sheets, films or plates can be obtained at low cost.

[Brief explanation of drawings]

FIG. 1a is a sectional view of the first laminate prepared by the method of the present invention, FIG. 1b is a sectional view of the second laminate, and FIG. 1c is a sectional view of the first laminate and the second laminate. FIG. 1d is a cross-sectional view of a conductive plastic plate obtained by the method of the present invention. 1...First laminate, 2...Second laminate, 1
DESCRIPTION OF SYMBOLS 1...Plastic film, 12...Transparent conductive coating layer, 21...Plastic base material, 22...
Adhesive composition layer.

Claims (1)

[Scope of Claims] 1 (a) A binder whose main component is an oligomer having at least two radically reactive unsaturated groups in its molecule; and a conductive material whose main component is tin oxide with an average particle size of 0.2 μm or less. a step of obtaining a transparent conductive paint containing powder; (b) a step of forming a coating layer of the transparent conductive paint on a plastic film with low adhesion to the coating film to obtain a first laminate; (c) forming a layer of an adhesive resin composition containing an oligomer having at least two radically reactive unsaturated groups in the molecule on a transparent plastic substrate to obtain a second laminate; (d) a step of laminating the first laminate and the second laminate such that the coating layer surface of the first laminate corresponds to the adhesive resin composition layer surface of the second laminate, and (e) A method for producing a conductive plastic sheet, film or plate, comprising the step of irradiating the laminate obtained in step (d) with ultraviolet rays or radiation. 2. The manufacturing method according to claim 1, wherein the conductive powder is contained in a proportion of 100 to 350 parts by weight based on 100 parts by weight of the binder. 3. The manufacturing method according to claim 1, wherein the material of the plastic film with low adhesion is polyester, polyethylene or polypropylene. 4. The manufacturing method according to claim 3, wherein the transparent conductive coating layer side of the plastic film with low adhesion is subjected to a mold release treatment.