JP6019166B1 - Method for producing antistatic sheet and method for producing antistatic molded body - Google Patents

Abstract

Disclosed is a method for producing an antistatic sheet capable of sufficiently increasing the water resistance and solvent resistance of an antistatic coating film despite the use of a styrenic resin substrate having a low heat resistant temperature as a base material. . The method for producing an antistatic sheet of the present invention uses a corona discharge treatment apparatus comprising a dielectric-coated electrode in which at least one surface of a styrene-based resin substrate is coated with a metal rod with a dielectric. A surface modification process by corona discharge treatment at a discharge amount of 30 W · min / m 2 or more, and a π-conjugated conductive polymer, polyanion, self-crosslinking resin on the surface of the surface-modified styrene resin substrate And a conductive polymer dispersion containing a dispersion medium to form an antistatic coating film. [Selection figure] None

Description

  The present invention relates to a method for producing an antistatic sheet for producing an antistatic sheet. Moreover, this invention relates to the manufacturing method of the antistatic molded object which shape | molds an antistatic sheet.

Antistatic sheets are used as protective sheets for protecting electronic component trays and the like. As an antistatic sheet, for example, a sheet obtained by applying a dispersion containing a π-conjugated conductive polymer and a binder to the surface of a resin film substrate to form an antistatic coating film is known. (See, for example, Patent Document 1).
However, the conventional antistatic sheet coated with an aqueous solution comprising a π-conjugated conductive polymer, or a tray molded product obtained by thermoforming the antistatic sheet, is not resistant to water resistance or resistance of the antistatic coating film. There was a problem of poor solvent properties. When using antistatic sheets and tray molded products that are thermoformed, wipe them off with gauze soaked in water or alcohol to remove dirt and particles adhering to the surface. Is made. However, when the water resistance or solvent resistance of the coating film is low, there is a problem that the antistatic coating film peels off during the wiping operation.
Therefore, it has been proposed to form an antistatic coating film using an aqueous solution in which a binder and a crosslinking agent are mixed with a π-conjugated conductive polymer and to bind it to the surface of the plastic substrate with heat (for example, a patent). Reference 2).
However, in a styrene resin substrate having low heat resistance, the water resistance and solvent resistance of the coating film may not be sufficiently improved. When using a base material with low heat resistance, it is necessary to set the drying temperature or heat treatment temperature of the coating film to 90 ° C. or lower in consideration of the heat resistance of the base material. It is necessary to perform heat treatment in a short time. However, when the binder used in combination with the crosslinking agent is heat-treated at 120 ° C. or higher, the crosslinking is instantaneously completed, but the binding is insufficient when the heat treatment is performed at a low temperature of about 90 ° C. for a short time. It has been difficult to sufficiently develop the solvent resistance.

Japanese Patent Laid-Open No. 1-225464 JP 2000-79662 A

  The present invention has been made in view of the above circumstances, and in spite of using a styrene resin substrate having a low heat resistant temperature as a base material, the water resistance and solvent resistance of the antistatic coating film are sufficiently increased. It is an object of the present invention to provide a method for producing an antistatic sheet that can be increased and a method for producing an antistatic molded article.

The present invention has the following aspects.
[1] A corona discharge treatment apparatus comprising a dielectric-coated electrode in which at least one surface of a styrene-based resin base material is coated with a metal rod with a dielectric material, and a corona discharge condition of 30 W · min / m ² or more. A step of surface treatment by electric discharge treatment, and a conductive polymer dispersion containing a π-conjugated conductive polymer, a polyanion, a self-crosslinkable resin and a dispersion medium on the surface of the surface-modified styrene resin substrate And a step of coating to form an antistatic coating film.
[2] The method for producing an antistatic sheet according to [1], wherein the dielectric-coated electrode is an electrode in which an aluminum rod is coated with ceramic.
[3] The method for producing an antistatic sheet according to [1] or [2], wherein the self-crosslinking resin includes a polyester resin having an alkali metal salt of an acid group and a glycidyl group-containing acrylic resin.
[4] The polyester resin is a polycondensate of a dicarboxylic acid component and a diglycol component, and the dicarboxylic acid component includes a dicarboxylic acid having a sulfonic acid alkali metal salt type substituent, and the diglycol component is The manufacturing method of the antistatic sheet as described in [3] containing diethylene glycol.
[5] A method for producing an antistatic molded article, wherein the antistatic sheet produced by the method for producing an antistatic sheet according to any one of [1] to [4] is molded.

  In the method for producing an antistatic sheet and the method for producing an antistatic molded article according to the present invention, the water resistance of the antistatic coating film and the styrene resin substrate having a low heat-resistant temperature are used as the substrate. The solvent resistance can be sufficiently increased.

<Antistatic sheet>
An antistatic sheet produced by the method for producing an antistatic sheet of the present invention comprises a styrene resin substrate and an antistatic coating film formed on at least one surface of the styrene resin substrate. .

(Styrenic resin substrate)
The styrene resin constituting the styrene resin substrate is a polymer containing a styrene monomer unit, and specifically includes a styrene hard resin, a rubber-reinforced styrene resin, and a styrene elastomer.

The styrenic hard resin is a resin that does not contain a rubber component, and may be a homopolymer consisting of only a styrenic monomer unit, or a single amount other than a styrenic monomer unit and a styrenic monomer unit. The copolymer containing a body unit may be sufficient.
Examples of the styrene monomer include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene and the like. These styrene monomers may be used alone or in combination of two or more. Of the styrenic monomers, styrene is preferred.
Other monomers include, for example, vinyl cyanide monomers (for example, acrylonitrile, methacrylonitrile, etc.), methacrylic acid ester monomers (for example, methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate). Etc.) and acrylic acid ester monomers (for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, etc.).
As the styrenic hard resin, a homopolymer of styrene (so-called “GPPS”) is preferable.

The rubber-reinforced styrene resin is a polymer in which a dispersed phase made of a rubber-like polymer is dispersed in an island shape (particulate form) in a continuous phase made of a styrene hard resin. The rubber-like polymer preferably has a graft chain made of a styrene hard resin.
Examples of the rubber-like polymer include conjugated diene polymers (for example, polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, polyisoprene, polychloroprene, etc.), acrylic polymers (for example, (meth) acrylic). Propyl acid, butyl (meth) acrylate), and olefin polymers (for example, ethylene-propylene-conjugated diene copolymer).
Specific examples of the rubber-reinforced styrene resin include impact-resistant polystyrene (so-called “HIPS”), ABS resin, AAS resin, AES resin, MBS resin, MABS resin and the like.
When the rubbery polymer is HIPS, the volume average particle diameter of the rubbery polymer is preferably in the range of 0.05 to 30 μm, more preferably in the range of 0.1 to 10 μm. More preferably, it is in the range of 0.2 to 7.0 μm, and particularly preferably in the range of 1.0 to 4.0 μm.

Examples of the styrenic elastomer include a styrene-conjugated diene block copolymer, a styrene-conjugated diene random copolymer, and hydrogenated products thereof. Unlike the rubber-reinforced styrene resin, the styrene elastomer does not contain rubbery polymer particles.
Examples of the styrene-conjugated diene block copolymer include a polymer having a polystyrene block formed by polymerizing a styrene monomer and a polyconjugated diene block formed by polymerizing a conjugated diene monomer. . The styrene-conjugated diene block copolymer comprises a polystyrene block obtained by homopolymerizing a styrene monomer, and a conjugated diene styrene copolymer block obtained by random copolymerization of a conjugated diene monomer and a styrene monomer. The polymer which has is mentioned.
Conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentanediene, and 1,3-hexadiene Etc. These conjugated diene monomers may be used alone or in combination of two or more. Among the conjugated diene monomers, 1,3-butadiene and 2-methyl-1,3-butadiene are preferable.
Specific examples of the styrene elastomer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene random copolymer (SBR), and hydrogenation of SBS. SEBS which is a product, SEPS which is a hydrogenated product of SIS, H-SBR which is a hydrogenated product of SBR, and the like.

  Among the styrene resins, at least one selected from the group consisting of GPPS, HIPS, and SBS is preferable because the effects of the present invention are particularly exhibited and the resin is a general-purpose resin.

Styrenic resin base materials include inorganic fillers, organic particles, antioxidants, heat stabilizers, lubricants, coupling agents, antiblocking agents, UV absorbers, foaming agents, mold release agents, as necessary. Additives such as flame retardants, colorants and waxes may be included.
Examples of inorganic fillers include metal oxides (eg, talc, mica, silica, alumina, potassium titanate whisker, calcium oxide, etc.), calcium carbonate, magnesium carbonate, calcium silicate, glass fibers, glass flakes, glass beads, and the like. Can be mentioned.
Examples of the organic particles include acrylic resin beads, polystyrene beads, nylon beads, and polyester beads.

The tensile elastic modulus of the styrene-based resin base material is preferably 1500 MPa or more, more preferably 1500 to 3000 MPa in both the flow direction (MD direction) and the width direction (TD direction) at the time of production. More preferably, it is 1600-2500 MPa. If the tensile modulus of the styrenic resin substrate is equal to or higher than the lower limit, the rigidity and strength of the antistatic sheet and the tray produced from the sheet can be improved, and the drawability of the sheet is also improved. . On the other hand, if the tensile elastic modulus of the styrene-based resin substrate is equal to or less than the upper limit value, the sheet handling workability is improved. Specifically, if the tensile elastic modulus of the styrene-based resin base material is equal to or less than the above upper limit value, it has moderate flexibility, so that the work of winding the sheet into a roll and the work of feeding out the roll are easy. It becomes.
The tensile elastic modulus is a value measured according to JIS K7127-1999 using a type 1B test piece at a temperature of 23 ° C. and a tensile speed of 50 mm / min.

In order to further improve the wettability of the conductive polymer dispersion, the adhesion to the antistatic coating film, the water resistance and the solvent resistance of the antistatic coating film, the styrenic resin base material is subjected to surface treatment in advance. May be applied. The surface treatment will be described later.
The surface of the styrenic resin substrate subjected to the surface treatment preferably has a wetting index of 38 mN / m or more, and more preferably 38 to 65 mN / m. The wetting index can be measured according to JIS K6768.
If the wetting index is equal to or higher than the lower limit value, the conductive polymer dispersion is applied without being repelled, so that an antistatic coating film is easily formed.

  The thickness (average value) of the styrene-based resin substrate is preferably 0.2 to 3 mm, more preferably 0.3 to 2 mm, further preferably 0.4 to 1.5 mm, and within that range Thus, it is appropriately adjusted according to the application. If the thickness of the styrenic resin substrate is equal to or greater than the lower limit, the moldability is improved and the rigidity and strength of the molded product are increased. On the other hand, if the thickness is equal to or less than the upper limit, the cost can be suppressed.

(Antistatic coating)
The antistatic coating film is a film containing a π-conjugated conductive polymer, a polyanion, and a crosslinked resin.

[Π-conjugated conductive polymer]
The π-conjugated conductive polymer is not particularly limited as long as the main chain is an organic polymer composed of a π-conjugated system. For example, a polypyrrole-based conductive polymer, a polythiophene-based conductive polymer, a polyacetylene-based polymer Conductive polymers, polyphenylene conductive polymers, polyphenylene vinylene conductive polymers, polyaniline conductive polymers, polyacene conductive polymers, polythiophene vinylene conductive polymers, and copolymers thereof Can be mentioned. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferable. From the viewpoint of conductivity, polythiophene-based conductive polymers are more preferable.

Examples of the polythiophene-based conductive polymer include polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), and poly (3-hexylthiophene). , Poly (3-heptylthiophene), poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), poly (3-octadecylthiophene), poly (3-bromothiophene), poly (3-chlorothiophene), poly (3-iodothiophene), poly (3-cyanothiophene), poly (3-phenylthiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene) , Poly (3-hydroxythiophene), poly (3-methoxythiophene), poly ( -Ethoxythiophene), poly (3-butoxythiophene), poly (3-hexyloxythiophene), poly (3-heptyloxythiophene), poly (3-octyloxythiophene), poly (3-decyloxythiophene), poly (3-dodecyloxythiophene), poly (3-octadecyloxythiophene), poly (3,4-dihydroxythiophene), poly (3,4-dimethoxythiophene), poly (3,4-diethoxythiophene), poly ( 3,4-dipropoxythiophene), poly (3,4-dibutoxythiophene), poly (3,4-dihexyloxythiophene), poly (3,4-diheptyloxythiophene), poly (3,4-dioctyl) Oxythiophene), poly (3,4-didecyloxythiophene), poly (3, -Didodecyloxythiophene), poly (3,4-ethylenedioxythiophene), poly (3,4-propylenedioxythiophene), poly (3,4-butenedioxythiophene), poly (3-methyl-4 -Methoxythiophene), poly (3-methyl-4-ethoxythiophene), poly (3-carboxythiophene), poly (3-methyl-4-carboxythiophene), poly (3-methyl-4-carboxyethylthiophene), Poly (3-methyl-4-carboxybutylthiophene) is mentioned.
Examples of the polypyrrole conductive polymer include polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-ethylpyrrole), poly (3-n-propylpyrrole), and poly (3-butyl Pyrrole), poly (3-octylpyrrole), poly (3-decylpyrrole), poly (3-dodecylpyrrole), poly (3,4-dimethylpyrrole), poly (3,4-dibutylpyrrole), poly (3 -Carboxypyrrole), poly (3-methyl-4-carboxypyrrole), poly (3-methyl-4-carboxyethylpyrrole), poly (3-methyl-4-carboxybutylpyrrole), poly (3-hydroxypyrrole) , Poly (3-methoxypyrrole), poly (3-ethoxypyrrole), poly (3-butoxypyrrole), poly (3-hexyl) Oxy pyrrole), poly (3-methyl-4-hexyloxy-pyrrole), poly (3-methyl-4-hexyloxy-pyrrole) and the like.
Examples of the polyaniline-based conductive polymer include polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-anilinesulfonic acid), and poly (3-anilinesulfonic acid).
Among the π-conjugated conductive polymers, poly (3,4-ethylenedioxythiophene) is particularly preferable from the viewpoint of conductivity and heat resistance.
The π-conjugated conductive polymer may be used alone or in combination of two or more.

[Polyanion]
The polyanion is a polymer having two or more monomer units having an anion group in the molecule. The anion group of the polyanion functions as a dopant for the π-conjugated conductive polymer and improves the conductivity of the π-conjugated conductive polymer.
The anion group of the polyanion is preferably a sulfo group or a carboxy group.
Specific examples of such polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacryl sulfonic acid, polymethacryl sulfonic acid, poly (2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfone. Polymers having a sulfonic acid group such as acid, polysulfoethyl methacrylate, poly (4-sulfobutyl methacrylate), polymethacryloxybenzenesulfonic acid, polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacryl carboxylic acid , Polymers having a carboxylic acid group such as polymethacrylcarboxylic acid, poly (2-acrylamido-2-methylpropanecarboxylic acid), polyisoprene carboxylic acid, polyacrylic acid and the like. These homopolymers may be sufficient and 2 or more types of copolymers may be sufficient.
Among these polyanions, a polymer having a sulfonic acid group is preferable, and polystyrene sulfonic acid is more preferable because conductivity can be further increased.
The said polyanion may be used individually by 1 type, and may use 2 or more types together.
The mass average molecular weight of the polyanion is preferably 20,000 to 1,000,000, and more preferably 100,000 to 500,000.

A polyanion coordinates with a π-conjugated conductive polymer to form a conductive complex.
However, in the polyanion, all the anion groups are not doped into the π-conjugated conductive polymer and have an excess anion group. Since this surplus anion group is a hydrophilic group, the conductive composite has water dispersibility.

  The content of the polyanion is preferably in the range of 0.1 to 10 mol, and more preferably in the range of 1 to 7 mol, with respect to 1 mol of the π-conjugated conductive polymer. When the polyanion content is less than 0.1 mol, the doping effect on the π-conjugated conductive polymer tends to be weak, and the conductivity may be insufficient. In addition, the dispersibility and solubility in the solvent are lowered, making it difficult to obtain a uniform dispersion. On the other hand, when the polyanion content is more than 10 mol, the content of the π-conjugated conductive polymer is decreased, and it is difficult to obtain sufficient conductivity.

In the polyanion, a part of its anion group is coordinated to the π-conjugated conductive polymer, and the π-conjugated conductive polymer and the polyanion form a complex. When the anion group of the polyanion is coordinated to the π-conjugated conductive polymer, the π-conjugated conductive polymer is doped to develop conductivity. An anionic group that does not coordinate to the π-conjugated conductive polymer of the polyanion serves to solubilize the complex in water.
The total content of the π-conjugated conductive polymer and the polyanion is preferably 0.05 to 5.0% by mass when the entire antistatic coating film is 100% by mass, and 0.5 to 4%. More preferably, it is 0.0 mass%. When the total content of the π-conjugated conductive polymer and the polyanion is less than 0.05% by mass, sufficient conductivity may not be obtained. May not be obtained.

[Crosslinked resin]
The crosslinked resin is a resin obtained by crosslinking a self-crosslinkable resin.
Self-crosslinking is a property capable of crosslinking even in the absence of a crosslinking agent. Self-crosslinking resins have at least one reactive functional group per molecule. The reactive functional group is a functional group capable of reacting with each other, and examples thereof include a sulfonic acid group, a carboxylic acid group, or an alkali metal salt thereof, an epoxy group, and an oxetane group. These reactive functional groups may be used alone or in combination of two or more.
The crosslinked resin plays a role of binding a complex of a π-conjugated conductive polymer and a polyanion to a styrene resin substrate.

  In the present invention, since the self-crosslinkable resin has higher water resistance and solvent resistance of the antistatic coating film, the polyester resin having an alkali metal salt of an acid group (hereinafter referred to as “polyester resin (1)”). And a glycidyl group-containing acrylic resin are preferred.

  The polyester resin (1) is a polycondensate of a dicarboxylic acid component and a diglycol component, and is a polyester resin having an alkali metal salt of an acid group (sulfonic acid group, carboxylic acid group, phosphoric acid group, etc.). Since this polyester resin (1) has a large polarity, it is excellent in water dispersibility and can be stably dispersed in water without using an emulsifier or a stabilizer.

Examples of the dicarboxylic acid component include phthalic acid, terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,5-dimethyl terephthalic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and orthophthalic acid. Examples include dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acid such as dodecanedicarboxylic acid, and alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid. Dicarboxylic acid may be used individually by 1 type, and may use 2 or more types together.
Wherein the dicarboxylic acid component, sulfonate alkali metal salt of the substituent (-SO 3 _- ^{X +,} however, X is an alkali metal ion.) Preferably includes dicarboxylic acid having a.

Sulfonic acid alkali metal salt substituent (-SO 3 _-. ^{X +,} however, X is an alkali metal ion) dicarboxylic acids having the sulfonic acid group in the dicarboxylic acid having a sulfonic acid group in the alkali metal salt Compound.
Examples of the dicarboxylic acid having a sulfonic acid group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalenic acid-2,7-dicarboxylic acid, and derivatives thereof. Examples of the alkali metal include sodium and potassium.
Sulfonic acid alkali metal salt substituent (-SO 3 _-. ^{X +,} however, X is an alkali metal ion) The dicarboxylic acid having a sodium salt and a derivative of 5-sulfoisophthalic acid are preferred.

In the dicarboxylic acid component, acid alkali metal salt substituent (-SO 3 _-. ^{X +,} however, X is an alkali metal ion) Examples of the dicarboxylic acid component other than the dicarboxylic acids having, aromatic dicarboxylic acids Preferably, terephthalic acid and isophthalic acid are more preferable. The aromatic nucleus of the aromatic dicarboxylic acid has a high affinity with a hydrophobic plastic, high adhesion to a styrene resin, and excellent hydrolysis resistance.

  The dicarboxylic acid having a sulfonic acid alkali metal salt type substituent is preferably contained in the total dicarboxylic acid component in an amount of 6 to 20 mol%, more preferably 10 to 18 mol%. If the content ratio of the dicarboxylic acid having a sulfonic acid alkali metal salt type substituent is equal to or higher than the lower limit, the dispersion time of the resin in water of the polyester resin (1) can be shortened and the solvent resistance can be further increased. If it is below the said upper limit, the water resistance of a polyester resin (1) will become higher.

  Examples of the diglycol component that forms the polyester resin (1) include diethylene glycol, aliphatic having 2 to 8 carbon atoms, or alicyclic glycol having 6 to 12 carbon atoms. Specific examples of the aliphatic having 2 to 8 carbon atoms or the alicyclic glycol having 6 to 12 carbon atoms include ethylene glycol, 1,3-propanediol, 1,2-propylene glycol, neopentyl glycol, 1,4- Examples include butanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,6-hexanediol, p-xylylene glycol, and triethylene glycol. These may be used individually by 1 type and may use 2 or more types together.

The diglycol component preferably contains diethylene glycol in order to further improve water resistance and solvent resistance.
When a diglycol component contains diethylene glycol, it is preferable to contain 20-80 mol% of diethylene glycol in all glycol components. Solvent resistance is obtained for alcohol even when the content ratio of diethylene glycol is outside the above range, but for aromatic solvents such as toluene and xylene other than alcohol, diethylene glycol is outside the above range. The solvent resistance may be insufficient.

The polyester resin (1) preferably has a number average molecular weight of 2,000 to 30,000, and more preferably 2,500 to 25,000. The number average molecular weight is a value determined by measurement with gel permeation chromatography and based on standard polystyrene.
If the number average molecular weight of the polyester resin (1) is not less than the above lower limit value, the water resistance and solvent resistance of the polyester resin (1) will be higher, and if it is not more than the above upper limit value, the water of the polyester resin (1) will be increased. Dispersibility becomes higher.

The production method of the polyester resin (1) is not particularly limited. For example, the dicarboxylic acid component and the diglycol component are esterified or transesterified at 130 to 200 ° C, and then at 200 to 250 ° C under reduced pressure conditions. The method of making polycondensation reaction is mentioned. Examples of the reaction catalyst used in the method for producing the polyester resin (1) include metal acetates such as zinc acetate and manganese acetate, metal oxides such as antimony oxide and germanium oxide, and titanium compounds.
The obtained polyester resin (1) may be added to water to form a water dispersion. Since the aqueous dispersion of the polyester resin (1) has a high solid content, it is difficult to obtain a uniform dispersion. Therefore, the polyester solid content is preferably 30% by mass or less.

  The glycidyl group-containing acrylic resin is a homopolymer of a glycidyl group-containing radical polymerizable unsaturated monomer, or a glycidyl group-containing radical polymerizable unsaturated monomer and another radical polymerizable unsaturated monomer copolymerizable with the monomer. It is a copolymer.

Examples of the glycidyl group-containing radical polymerizable unsaturated monomer include glycidyl ethers such as glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether. The glycidyl group-containing radical polymerizable unsaturated monomer may be used alone or in combination of two or more.
The content ratio of the glycidyl group-containing radically polymerizable unsaturated monomer is preferably 10 to 100% by mass, more preferably 20 to 100% by mass, based on all monomers.
It is considered that the glycidyl group-containing acrylic resin has a glycidyl group-containing radical polymerizable unsaturated monomer unit, thereby promoting self-crosslinking and improving water resistance and solvent resistance. In particular, the improvement in solvent resistance with respect to ketone solvents such as acetone and methyl ethyl ketone and ester solvents such as ethyl acetate and butyl acetate is remarkable.
Solvent resistance to alcohol can be obtained even when the content of the glycidyl group-containing radical polymerizable unsaturated monomer is less than 10% by mass, but it is resistant to ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate and butyl acetate. Insufficient sex.

Other radical polymerizable unsaturated monomers copolymerizable with glycidyl group-containing radical polymerizable unsaturated monomers include vinyl esters, unsaturated carboxylic acid esters, unsaturated carboxylic acid amides, unsaturated nitriles, unsaturated carboxylic acids, allyls. Examples thereof include compounds, nitrogen-containing vinyl monomers, hydrocarbon vinyl monomers, and vinyl silane compounds. Other radically polymerizable unsaturated monomers may be used alone or in combination of two or more.
As other radically polymerizable unsaturated monomers, it is preferable to use unsaturated carboxylic acid monomers such as acrylic acid and methacrylic acid because the effect of improving solvent resistance is further exhibited by crosslinking with a glycidyl group.
It is preferable that the content rate of an unsaturated carboxylic acid monomer is 5-20 mass% in all the monomers. If the content ratio of the unsaturated carboxylic acid monomer is equal to or higher than the lower limit value, the effect of using the unsaturated carboxylic acid monomer is sufficiently exhibited. It can suppress that property falls.

The method for producing the glycidyl group-containing acrylic resin is not particularly limited, and for example, the glycidyl group-containing acrylic resin can be produced by emulsion polymerization.
In the production of glycidyl group-containing acrylic resin by emulsion polymerization, for example, ion exchange water, a polymerization initiator and a surfactant are charged in a reaction tank, and then ion exchange water and a surfactant are charged in a dropping tank, and monomers are added. Then, after producing an emulsion, the emulsion is subjected to emulsion radical polymerization by dropping the emulsion into a reaction vessel. The reaction temperature is preferably 60 to 100 ° C., and the reaction time is preferably 4 to 10 hours.
As the surfactant used for the emulsion polymerization, one or more of an anionic surfactant, a nonionic reactive surfactant and a non-reactive surfactant can be used.
As a polymerization initiator used for emulsion polymerization, a general radical polymerizable initiator, for example, a water-soluble peroxide such as potassium persulfate, ammonium persulfate, hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, or the like Or an azo compound such as azobisisobutyronitrile.

When the self-crosslinking resin comprises the polyester resin (1) and the glycidyl group-containing acrylic resin, the polyester resin (1) / glycidyl group-containing acrylic resin has a solid mass in order to appropriately self-crosslink. The ratio is preferably 10/90 to 80/20, and more preferably 20/80 to 70/30.
When the polyester resin (1) is 10% by mass or more, that is, the glycidyl group-containing acrylic resin is 90% by mass or less, the adhesion to the styrenic resin substrate and the transparency of the antistatic coating film become higher, When the polyester resin (1) is 80% by mass or less, that is, the glycidyl group-containing acrylic resin is 20% by mass or more, water resistance and solvent resistance are further increased.

  The self-crosslinking resin may contain an antifoaming agent, a wetting agent, a surfactant, a thickening agent, a plasticizer, an antioxidant, an ultraviolet absorber, a preservative, and the like as necessary.

  The content of the crosslinked resin in the antistatic coating film is preferably 87.0 to 98.5% by mass, and more preferably 90.0 to 98.0% by mass. If the content of the crosslinked resin is not less than the lower limit, the water resistance and solvent resistance of the antistatic coating film can be further increased, and if it is not more than the upper limit, sufficient antistatic properties can be ensured.

  The thickness (average value) of the antistatic coating film is preferably from 0.01 to 10 μm, more preferably from 0.05 to 7 μm, further preferably from 0.1 to 5 μm, depending on the application. Selected.

The surface resistance value of the antistatic sheet of the present invention is preferably 1 × 10 ⁹ Ω or less, more preferably 1 × 10 ⁴ to 1 × 10 ⁹ Ω, and 1 × 10 ⁵ to 10 ⁸ Ω. More preferably it is. If the surface resistance value of the antistatic sheet is within the above range, even if it is formed into a tray molded product, generation of static electricity can be prevented, and failure and contamination of electronic components to be stored can be prevented.
The surface resistance value is a value measured according to JIS K6911.

<Method for producing antistatic sheet>
The method for producing an antistatic sheet according to the present invention comprises a surface modification step in which at least one surface of a styrenic resin substrate is surface-modified by corona discharge treatment, and the surface of the surface-modified styrene resin substrate is electrically conductive. And an antistatic coating film forming step of forming an antistatic coating film by applying a functional polymer dispersion.
Specific examples of the method for producing the antistatic sheet of the present invention include the following methods (a) to (c).
(A) A styrene resin is melted with an extruder, discharged from a T die attached to the extruder, and formed into a film to obtain a styrene resin substrate (base material forming step). At least one surface of the styrenic resin substrate is subjected to corona discharge treatment for surface modification (surface modification step). A conductive polymer dispersion is applied to the surface of the surface-modified styrenic resin substrate and dried (antistatic coating film forming step). The antistatic sheet thus obtained is wound on a roll. This method is an inline process in which a series of steps are continuously performed.
(B) A styrenic resin is melted with an extruder, discharged from a T die attached to the extruder to form a styrenic resin base material, and then wound on a roll (base material forming step). Thereafter, a roll-like styrene resin substrate is fed out, and at least one surface of the fed styrene resin substrate is subjected to corona discharge treatment to perform surface modification (surface modification step). A conductive polymer dispersion is applied to the surface of the surface-modified styrenic resin substrate and dried (antistatic coating film forming step). The antistatic sheet thus obtained is again wound on a roll. In this method, the production of the styrene-based resin substrate and the surface modification are discontinuous, and this is an offline process.
(C) A styrene resin is melted with an extruder, discharged from a T die attached to the extruder, and formed into a film to obtain a styrene resin substrate (substrate forming step). Thereafter, the roll-shaped styrene-based resin substrate is fed out, and at least one surface of the fed-out styrene-based resin substrate is subjected to corona discharge treatment to be surface-modified, and then wound on a roll (surface modifying step). Thereafter, the roll-modified styrenic resin base material having a surface modified is fed out, coated with a conductive polymer dispersion, and dried (antistatic coating film forming step). The antistatic sheet thus obtained is again wound on a roll. This method is an off-line process in which surface modification and application of the conductive polymer dispersion are discontinuous.
Among the above (a) to (c), (a) is preferable from the viewpoint of production efficiency.

(Surface modification process)
In the corona discharge treatment in the surface modification step, a corona discharge treatment apparatus including an electrode and a counter electrode roll is used, a styrene resin substrate is passed between the electrode and the counter electrode roll, and a high frequency high voltage is applied between them. Apply. Corona discharge is generated by applying a high frequency high voltage.

In the present invention, the electrode used for the corona discharge treatment is a dielectric coated electrode in which a metal rod is coated with a dielectric.
Examples of the metal rod include an aluminum rod and a stainless steel rod, and examples of the dielectric include ceramic and quartz. Among the dielectric-coated electrodes, the wettability of the conductive polymer dispersion and the water resistance and solvent resistance of the antistatic coating film are higher, and therefore, a dielectric-coated electrode in which an aluminum rod is coated with ceramic is preferable.
The counter electrode roll is a roll on which a styrene-based resin base material is wound, and is a roll installed at an arbitrary interval with respect to the electrode so as to be subjected to corona discharge treatment stably and uniformly.
As the counter electrode roll, a roll made of metal, such as aluminum or stainless steel, ceramic, silicone rubber, ethylene / propylene / conjugated diene copolymer rubber (EPT rubber), chlorosulfonated polyethylene rubber, etc., or chromium A roll plated with such as is used. Among these, chrome-plated stainless steel rolls and EPT rubber were lined from the standpoint of wear resistance on the roll surface, ease of wiping and cleaning, and prevention of particle contamination and chemical contamination on the surface of the styrene resin substrate. A metal roll is preferred.
The distance between the electrode and the counter electrode roll is preferably 1 to 5 mm, and more preferably 2 to 3 mm. If the distance between the electrode and the counter electrode roll is equal to or greater than the lower limit, unevenness of treatment is unlikely to occur and the coating film is likely to be uniform, and if the gap is equal to or less than the upper limit, Damage can be prevented.

Discharge amount in the corona discharge treatment is a 30 W · min / ^{m 2} or more, preferably 32～300W · min / ^{m 2,} and more preferably 35～250W · min / ^{m 2.}
When the discharge amount is not less than the lower limit, the surface of the styrene resin substrate can be sufficiently wetted by the conductive polymer dispersion, and the adhesion with the antistatic coating film, the antistatic coating film Water resistance and solvent resistance can be improved. On the other hand, if the discharge amount is less than or equal to the upper limit value, it is possible to prevent the surface of the styrene resin substrate from being damaged. In addition, it is possible to suppress bleeding out of the surface of the styrenic resin base material, and to improve the adhesion with the antistatic coating film and the water resistance and solvent resistance of the antistatic coating film. it can.
When the electrode used for corona discharge is a dielectric-coated electrode and the discharge amount is 30 W · min / m ² or more, the water resistance and solvent resistance of the antistatic coating film are further improved.

The corona discharge treatment can be performed in an air atmosphere, a nitrogen gas atmosphere, an oxygen gas atmosphere, a mixed gas atmosphere of nitrogen and oxygen, or the like. Among these, since the production cost is low, it is preferable to carry out in an air atmosphere.
The frequency of discharge in the corona discharge treatment is preferably 5 to 50 kHz, and more preferably 20 to 45 kHz. If a frequency is more than the said lower limit, the uniformity of a corona discharge process will improve and a process nonuniformity can be suppressed. On the other hand, if the frequency is equal to or lower than the upper limit value, stable treatment can be achieved even when corona discharge treatment is performed at low output.

(Antistatic coating film forming process)
In the antistatic coating film forming step, the conductive polymer dispersion applied to the surface of the surface-modified styrenic resin substrate is composed of a π-conjugated conductive polymer, a polyanion, a self-crosslinking resin, and a dispersion medium. Including.

[Dispersion medium]
As the dispersion medium, any one of water, an organic solvent, and a mixed solution of water and an organic solvent can be used.
As the organic solvent, a water-soluble solvent is preferable because the conductive polymer dispersion can be made uniform. Examples of the water-soluble solvent include alcohols such as methanol, ethanol and isopropanol, N-methyl-2-pyrrolidone, N-methylacetamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylene Polar solvents such as phosphortriamide, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, phenols such as cresol, phenol, xylenol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1 , 3-butylene glycol, 1,4-butylene glycol, glycerin, diglycerin, D-glucose, D-glucitol, isoprene glycol, butanediol, 1,5-pe Polyhydric aliphatic alcohols such as tandiol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, carbonate compounds such as ethylene carbonate and propylene carbonate, ether compounds such as dioxane and diethyl ether, dialkyl ethers, Chain ethers such as propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether, heterocyclic compounds such as 3-methyl-2-oxazolidinone, acetonitrile, glutaronitrile, methoxyacetonitrile, propionitrile, benzonitrile, etc. Nitrile compounds and the like. These solvents may be used alone or as a mixture of two or more.

[Method for preparing conductive polymer dispersion]
The conductive polymer dispersion described above is produced, for example, by preparing an aqueous solution containing a π-conjugated conductive polymer and a polyanion and then adding a self-crosslinking resin and a dispersion medium.

[Coating method]
Examples of the method for applying the conductive polymer dispersion include a gravure coater, a roll coater, a curtain flow coater, a spin coater, a bar coater, a reverse coater, a kiss coater, a phantom coater, a rod coater, an air doctor coater, and a knife coater. A coating method using a coater such as a blade coater, cast coater or screen coater, a spraying method using a sprayer such as air spray, airless spray or rotor dampening, a dipping method or the like can be applied.

After coating the conductive polymer dispersion, it is preferable to heat and dry.
The drying temperature is preferably 40 to 90 ° C, more preferably 50 to 85 ° C, and further preferably 60 to 80 ° C. If the drying temperature is 40 ° C. or higher, the sheet can be sufficiently dried even if the sheet feeding speed is high, the adhesion between the antistatic coating film and the styrene resin substrate, and the water resistance and resistance of the antistatic coating film. Solvent property can be made higher. On the other hand, if the drying temperature is 90 ° C. or lower, the sheet shape can be maintained while preventing the styrene resin base material from being softened.
Moreover, it is preferable to cure after drying. When not cured, the antistatic coating film immediately after drying may not exhibit sufficient water resistance and solvent resistance.
As the curing conditions, it is preferable that the antistatic sheet after drying is left indoors at 20 to 50 ° C. for 20 hours or more. If cured under these conditions, the water resistance and solvent resistance of the antistatic coating film can be further increased.

(Function and effect)
As described above, in the method for producing an antistatic sheet of the present invention, a dielectric-coated electrode is used as an electrode used for corona discharge treatment of a styrenic resin substrate, and the corona discharge amount is 30 W · min / m ² or more. . In addition, a conductive polymer dispersion containing a π-conjugated conductive polymer, a polyanion, a self-crosslinkable resin, and a dispersion medium is applied to the surface of the surface-modified styrenic resin substrate. Thereby, even if the drying temperature of the conductive polymer dispersion liquid after coating is lowered, it is possible to form an antistatic coating film that is sufficiently bound to the styrenic resin substrate and sufficiently crosslinked. Therefore, according to the present invention, even if a styrene resin substrate is used as the substrate, the water resistance and solvent resistance of the antistatic coating film formed on the surface of the substrate can be increased.

<Antistatic molding and its production method>
The antistatic molded article of the present invention is produced by molding the antistatic sheet. As an antistatic molded object, the tray molded product which accommodates an electronic component etc. is mentioned, for example.
As the molding method, for example, various thermoforming methods such as a vacuum forming method, a pressure forming method, a plug assist forming method, and a vacuum / pressure forming method can be applied. In these molding methods, it is possible to perform so-called drawing molding in which an antistatic sheet is brought into close contact with a convex or concave mold to form a concave or convex section.
Although it does not restrict | limit especially as shaping | molding temperature, 120-180 degreeC is preferable from the point of a moldability.
The surface resistance value of the antistatic molded body in the present invention is preferably 1 × 10 ⁹ Ω or less, similarly to the antistatic sheet of the present invention, and is 1 × 10 ⁴ to 1 × 10 ⁹ Ω. Is more preferable, and 1 × 10 ⁵ to 1 × 10 ⁸ Ω is even more preferable.

(Production Example 1) Preparation of polystyrene sulfonic acid 206 g of sodium styrene sulfonate was dissolved in 1000 ml of ion-exchanged water, and 1.14 g of ammonium persulfate oxidizing agent solution previously dissolved in 10 ml of water was stirred at 80 ° C. The solution was added dropwise for 20 minutes, and the solution was stirred for 2 hours.
1000 ml and 10,000 ml of ion-exchanged water diluted with 10% by mass of sulfuric acid diluted to 10% by mass were added to the sodium styrenesulfonate-containing solution thus obtained, and about 10,000 ml of the polystyrenesulfonic acid-containing solution was removed using an ultrafiltration method. Then, 10,000 ml of ion-exchanged water was added to the remaining liquid, and about 10,000 ml of solution was removed using an ultrafiltration method. The above ultrafiltration operation was repeated three times.
Furthermore, about 10,000 ml of ion-exchanged water was added to the obtained filtrate, and about 10,000 ml of solution was removed using an ultrafiltration method. This ultrafiltration operation was repeated three times.
The ultrafiltration conditions were as follows (the same applies to other examples).
Molecular weight cut off of ultrafiltration membrane: 30K
Cross flow type Supply liquid flow rate: 3000 ml / min Membrane partial pressure: 0.12 Pa
Water in the obtained solution was removed under reduced pressure to obtain colorless solid polystyrene sulfonic acid.

(Production Example 2) Preparation of Polystyrenesulfonic Acid Doped Poly (3,4-ethylenedioxythiophene) Aqueous Solution 14.2 g of 3,4-ethylenedioxythiophene and 36.7 g of polystyrenesulfonic acid obtained in Production Example 1 A solution dissolved in 2000 ml of ion-exchanged water was mixed at 20 ° C.
While maintaining the mixed solution thus obtained at 20 ° C. and stirring, 29.64 g of ammonium persulfate dissolved in 200 ml of ion exchange water and 8.0 g of ferric sulfate oxidation catalyst solution were slowly added, The reaction was stirred for 3 hours.
2000 ml of ion-exchanged water was added to the resulting reaction solution, and about 2000 ml of solution was removed using an ultrafiltration method. This operation was repeated three times.
Then, 200 ml of sulfuric acid diluted to 10% by mass and 2000 ml of ion-exchanged water are added to the treatment liquid that has been subjected to the filtration treatment, and about 2000 ml of the treatment liquid is removed using an ultrafiltration method. Ion exchange water was added and about 2000 ml of liquid was removed using ultrafiltration. This operation was repeated three times.
Furthermore, 2000 ml of ion-exchanged water was added to the obtained treatment liquid, and about 2000 ml of the treatment liquid was removed using an ultrafiltration method. This operation was repeated five times to obtain about 1.2% by mass of a blue polystyrenesulfonic acid-doped poly (3,4-ethylenedioxythiophene) (PEDOT-PSS) aqueous solution.

(Production Example 3) Preparation of polyester resin A four-necked flask equipped with a distillation tube, a nitrogen inlet tube, a thermometer, and a stirrer was 854 parts by mass of dimethyl terephthalate, 355 parts by mass of 5-sodium sulfoisophthalic acid, ethylene glycol 186 parts by mass, 742 parts by mass of diethylene glycol, and 1 part by mass of zinc acetate were charged as a reaction catalyst. Thereafter, the temperature in the flask was raised from 130 ° C. to 170 ° C. over 2 hours to cause transesterification, and then 730 parts by mass of isophthalic acid and 1 part by mass of antimony trioxide were added. The temperature was raised over time to carry out the esterification reaction. Subsequently, the temperature was gradually raised and the pressure was reduced, and a polycondensation reaction was finally performed at a reaction temperature of 250 ° C. and a degree of vacuum of 5 mmHg or less for 1 hour. Then, it cooled and added ion-exchange water under normal pressure, and obtained the polyester resin whose non volatile matter is 25 mass%.

(Production Example 4) Preparation of glycidyl group-containing acrylic resin 18 parts by mass of ion-exchanged water in a beaker, Eleminol RS-3000 as a surfactant (manufactured by Sanyo Chemical Industries, Ltd., anionic surfactant, active ingredient 50% by mass) 3 parts by weight were charged. Then, 20 mass parts of glycidyl methacrylate, 13.6 mass parts of methyl methacrylate, and 6.4 mass parts of butyl acrylate were thrown in, stirring the inside of a beaker, and the monomer emulsion was produced.
Next, in a four-necked flask equipped with a condenser, a monomer dropping funnel, a thermometer, and a stirrer, 37.5 parts by mass of ion exchange water, 1 part by mass of a surfactant (Eleminol RS-3000), 0 potassium persulfate .5 parts by mass were charged. Thereafter, the atmosphere in the flask was replaced with nitrogen, followed by heating, and the monomer emulsion was added dropwise at 75 ° C. over 4 hours. The reaction was continued by maintaining the liquid temperature at 75 to 85 ° C. even after the completion of the dropping, and the reaction was cooled 4 hours after the completion of the dropping. After cooling, ion exchange water was further added to obtain a glycidyl group-containing acrylic resin having a nonvolatile content of 25% by mass.

(Production Example 5) Preparation of self-crosslinkable resin The polyester resin obtained in Production Example 3 and the glycidyl group-containing acrylic resin obtained in Production Example 4 were blended at a mass ratio of 50/50, and the nonvolatile content was 25% by mass. A self-crosslinking resin was obtained.

(Production Example 6) Preparation of Conductive Polymer Dispersion The PEDOT-PSS aqueous solution obtained in Production Example 2 and the self-crosslinkable resin obtained in Production Example 5 were blended at a mass ratio of 60/40 to obtain a nonvolatile content of 10 A 7% by mass of a conductive polymer dispersion was obtained.

(Production Example 7) Production of Styrenic Resin Substrate (a) Pellets of rubber-reinforced styrene resin (a-1) are supplied to a single screw extruder and melted at a cylinder temperature of 200 to 250 ° C. Molten resin was discharged from a T die attached to the tip. By cooling the molten resin with a chill roll at 40 to 70 ° C., a sheet-like styrene resin substrate (a) having a thickness of 0.7 mm and a width of 700 mm was produced and wound up. The tensile elastic modulus in the MD direction of the obtained styrene-based resin substrate (a) was 2010 MPa, and the tensile elastic modulus in the TD direction was 1990 MPa.
The rubber-reinforced styrene-based resin (a-1) is PS Japan Co., Ltd., impact-resistant polystyrene HIPS HT478.

(Production Example 8) Production of Styrenic Resin Base Material (b) 15% by mass of rubber-reinforced styrene resin (b-1), 30% by mass of styrene hard resin (b-2), and styrene elastomer (b-3) A styrene resin mixture was obtained by dry blending with 55% by mass. This styrene resin mixture was supplied to a single screw extruder, melted at a cylinder temperature of 200 to 250 ° C., and the molten resin was discharged from a T die attached to the tip of the single screw extruder. By cooling the molten resin with a chill roll at 40 to 70 ° C., a sheet-like styrenic resin substrate (b) having a thickness of 0.7 mm and a width of 700 mm was produced and wound up. The resulting styrene resin substrate (b) had a tensile modulus in the MD direction of 2030 MPa and a tensile modulus in the TD direction of 1820 MPa.
The rubber-reinforced styrene-based resin (b-1) is impact-resistant polystyrene HIPS 475D manufactured by PS Japan. The styrene hard resin (b-2) is PS Japan, polystyrene GPPS, SGP10. The styrene elastomer (b-3) is styrene-butadiene-styrene block copolymer SBS, Asaflex 825S manufactured by Asahi Kasei Chemicals Corporation.

Example 1
One surface of the styrenic resin substrate (a) obtained in Production Example 7 was subjected to surface treatment by corona discharge treatment at a discharge amount of 40 W · min / m ² using a corona discharge treatment apparatus (manufactured by Kasuga Electric). . In this example, a dielectric-coated electrode (electrode A) in which an aluminum rod is covered with ceramic is used as an electrode for corona discharge treatment, and a chromium-plated stainless steel roll (roll C) is used as a counter electrode roll facing the electrode. Using.
Next, after the surface-treated styrenic resin substrate (a) was cut into 30 cm square, the conductive polymer dispersion obtained in Production Example 6 was applied to the surface-treated surface using a # 2 bar coater. Then, it was dried at 75 ° C. for 1 minute using a hot air oven. Subsequently, the film was cured for one day in a room at 25 ° C., and an antistatic coating film was formed to obtain an antistatic sheet.

(Examples 2-4, Comparative Examples 1-5)
An antistatic sheet was obtained in the same manner as in Example 1 except that the electrode for corona discharge treatment, the counter electrode roll, and the discharge amount were changed as shown in Tables 1 and 2. However, in Comparative Example 5, since the styrenic resin substrate (a) repels the conductive polymer dispersion, an antistatic coating film could not be formed and an antistatic sheet could not be obtained.

(Example 5)
An antistatic sheet was obtained in the same manner as in Example 1 except that the styrene resin substrate (b) obtained in Production Example 8 was used instead of the styrene resin substrate (a) obtained in Production Example 7. .

(Comparative Example 6)
The styrene resin substrate (b) obtained in Production Example 8 was used instead of the styrene resin substrate (a) obtained in Production Example 7, and the discharge amount of the corona discharge treatment was changed as shown in Table 2. Except that, an antistatic sheet was obtained in the same manner as in Example 1. However, since the styrene resin substrate (b) repels the conductive polymer dispersion, an antistatic coating film could not be formed, and an antistatic sheet could not be obtained.

  The electrode B for corona discharge treatment in Tables 1 and 2 is a metal electrode made of an aluminum rod, and the counter electrode roll D is a stainless steel roll lined with EPT.

<Evaluation>
The surface tension of the surface treatment surface in the styrene resin substrate was measured as follows. The measurement results are shown in Tables 1 and 2.
The obtained antistatic sheet was evaluated for surface resistance, water resistance, alcohol resistance, and vacuum formability as follows. The evaluation results are shown in Tables 1 and 2.

[surface tension]
In accordance with JIS K6768, the surface tension was measured using a wet tension test mixture (manufactured by Wako Pure Chemical Industries, Ltd.).

[Surface resistance value]
The surface resistance value (Ω) of the obtained antistatic sheet was measured according to JIS K6911 using Hiresta manufactured by Mitsubishi Chemical Corporation.

[water resistant]
The antistatic coating film of the obtained antistatic sheet was wiped with a gauze soaked in deionized water at a pressing pressure of 10 kPa at a pressure of 10 kPa for 10 reciprocations of 10 mm, and the surface of the portion was dried. The resistance value was measured as described above.
A surface resistance value (Ω) of less than 1 × 10 ¹⁰ was evaluated as ○ (pass), and 1 × 10 ¹⁰ or more was evaluated as × (fail).

[Alcohol resistance]
The antistatic coating film of the obtained antistatic sheet was wiped with a gauze soaked in isopropyl alcohol at a pressing pressure of 10 kPa at a pressure of 10 kPa for 10 reciprocations of 100 mm. After the wiped portion was dried, the surface resistance of that portion was Values were measured as before.
A surface resistance value (Ω) of less than 1 × 10 ¹⁰ was evaluated as ○ (pass), and 1 × 10 ¹⁰ or more was evaluated as × (fail).

[Vacuum formability]
The obtained antistatic sheet was set in a vacuum forming machine with the antistatic coating film side down, and heated while measuring the sheet surface temperature with an upper heater. When the sheet surface temperature reached 120 to 140 ° C., the concave mold was lifted from the lower side and evacuated while being pressed against the sheet, and held for 20 seconds. Then, it cooled at 40 degreeC and took out the obtained molded article.
The shape and dimensions of the vacuum molded product were a circular cylinder with a diameter of the opening of 90 mm and a height of 45 mm, and the molding magnification was 3 times.
With respect to the bottom and side surfaces of the obtained vacuum molded product, the surface resistance value (Ω) of the antistatic coating film side was measured in the same manner as described above.
A surface resistance value (Ω) of less than 1 × 10 ¹⁰ was evaluated as ○ (pass), and 1 × 10 ¹⁰ or more was evaluated as × (fail).

In Examples 1 to 5, although the styrene resin base material was used as the base material, the obtained antistatic sheet had high water resistance and alcohol resistance, and was excellent in vacuum moldability.
In Comparative Examples 1 to 4 using an aluminum rod as an electrode for corona discharge treatment, the water resistance of the obtained antistatic sheet was low.
In Comparative Examples 5 and 6 in which the amount of discharge in the corona discharge treatment was 30 W · min / m ² or less, evaluation was not possible because the wettability of the styrene resin substrate was low and an antistatic coating film could not be formed.

  Although the present invention has been described above with specific embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above-described embodiments. Further, it is apparent from the scope of the claims that embodiments with such changes or improvements can also be included in the technical scope of the present invention.

Claims (4)

At least one surface of the styrenic resin substrate is subjected to corona discharge treatment using a corona discharge treatment apparatus including a dielectric-coated electrode in which a metal rod is coated with a dielectric material under a discharge amount of 30 W · min / m ² or more. And surface modification process,
An antistatic coating film is formed by applying a conductive polymer dispersion containing a π-conjugated conductive polymer, polyanion, self-crosslinkable resin and dispersion medium to the surface of the surface-modified styrene resin substrate. a step of, the possess,
The method for producing an antistatic sheet, wherein the self-crosslinking resin includes a polyester resin having an alkali metal salt of an acid group and a glycidyl group-containing acrylic resin .   The method for producing an antistatic sheet according to claim 1, wherein the dielectric-coated electrode is an electrode obtained by coating an aluminum rod with ceramic. The polyester resin is a polycondensate of a dicarboxylic acid component and a diglycol component, the dicarboxylic acid component contains a dicarboxylic acid having a sulfonic acid alkali metal salt type substituent, and the diglycol component contains diethylene glycol. The manufacturing method of the antistatic sheet | seat of Claim 1 or 2 containing. The manufacturing method of the antistatic molded object which shape | molds the antistatic sheet manufactured by the manufacturing method of the antistatic sheet of any one of Claims 1-3 .