Coating agents, coating films, and laminates

Abstract

To provide a coating agent capable of forming a coating film excellent in conductivity and transparency.SOLUTION: The coating agent contains a carboxyl group-containing resin, a carbon-based material, a metal oxide, and an aqueous medium. The content of the carbon-based material is preferably 10-200 pts.mass based on 100 pts.mass of the carboxyl group-containing resin. The content of the metal oxide is preferably 30-1,500 pts.mass based on 100 pts.mass of the carboxyl group-containing resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a coating agent capable of forming a coating film having excellent conductivity.

Background Art

[0002] In recent years, due to the increasing integration of electrical and electronic components and semiconductor devices, there have been many problems of product damage caused by dust and static electricity. In the assembly, transportation, and packaging processes of various components used in the manufacture of such products, in order to reduce the influence of dust and static electricity on the products, a substance having conductivity is used to impart antistatic and conductive properties to the materials used in assembly, transportation, and packaging.

[0003] As an example of a method for imparting conductivity to various materials, a coating agent containing a conductive component is applied to various substrates to form a coating film. As such a coating agent, for example, a coating agent containing a carbon-based material as a binder component and a conductive component is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the coating film obtained by using the conductive coating agent disclosed in Patent Document 1 has a problem that although it has conductivity, its transparency is low due to coloring derived from the carbon-based material, and its use applications are limited.

[0006] In view of the problems of the prior art as described above, it is a technical problem of the present invention to provide a coating agent capable of forming a coating film having excellent conductivity and transparency.

Means for Solving the Problems

[0007] As a result of diligent research to solve the above problems, the present inventors have found that a coating agent containing a carboxyl group-containing resin, a carbon-based material, a metal oxide, and an aqueous medium solves the above problems, and have arrived at the present invention. In other words, the gist of the present invention is as follows:

[0008] (1) A coating agent containing a resin containing carboxyl groups, a carbon-based material, a metal oxide, and an aqueous medium. A coating agent wherein the resin containing carboxyl groups is an acid-modified polyolefin resin and / or polyester resin, the carbon-based material is a carbon nanotube, and the metal oxide is tin oxide. . (2) The coating agent of (1), wherein the carbon-based material content is 10 to 200 parts by mass per 100 parts by mass of the resin containing carboxyl groups. (3) (1) The metal oxide content is 30 to 1500 parts by mass per 100 parts by mass of resin containing carboxyl groups. or (2) A coating agent. (4) (1) (3) A coating film consisting of one of the following coating agents. (5)(4) A laminate containing a coating film. [Effects of the Invention]

[0009] The coating agent of the present invention exhibits excellent conductivity and can produce a coating film with good transparency. Therefore, it can be applied to applications where transparency is required, which was not possible with conventional coatings. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. The coating agent of the present invention contains a resin containing carboxyl groups, a carbon-based material, a metal oxide, and an aqueous medium. Preferably, the resin containing carboxyl groups, the carbon-based material, and the metal oxide are dispersed in the aqueous medium.

[0011] <Resin containing carboxyl groups> Examples of carboxyl group-containing resins constituting the coating agent of the present invention include polyester resins, acid-modified polyolefin resins, acrylic resins, urethane resins, polyamide resins, and polyimide resins. Among these, polyester resins and acid-modified polyolefin resins are preferred from the viewpoint of coating properties to the substrate and adhesion to the substrate. Furthermore, these resins may contain multiple types, and other resin components, such as silicone resin, styrene resin, epoxy resin, phenolic resin, melamine resin, and urea resin, may also be included, as long as they do not impair performance.

[0012] (Polyester resin) Polyester resins, which contain carboxyl groups, are mainly composed of polybasic acid components and polyhydric alcohol components.

[0013] The polybasic acid components constituting the polyester resin are not particularly limited and include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 3-tert-butylisophthalic acid, and diphenic acid; saturated aliphatic dicarboxylic acids such as oxalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanediic acid, aicosanedioic acid, and hydrogenated dimer acid; unsaturated aliphatic dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, and dimer acid; and 1,4-cyclohexa Examples of polybasic acid components include alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid and its anhydride, tetrahydrophthalic acid and its anhydride, trimellitic acid, benzophenonetetracarboxylic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, benzophenonetetracarboxylic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), and 1,2,3,4-butanetetracarboxylic acid, which have three or more functionalities. These polybasic acid components can be used alone or in combination of two or more.

[0014] Among the above-mentioned polybasic acids, terephthalic acid and isophthalic acid are preferred. The content of terephthalic acid or isophthalic acid in the polybasic acid component is preferably 20 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more in terms of the content of either one or the total content of both.

[0015] When a polybasic acid having three or more functional groups is used as the polybasic acid, it is preferably 5 mol% or less, and more preferably 3 mol% or less in the polybasic acid component of the polyester resin.

[0016] As the polybasic acid, a polybasic acid having a sulfonic acid group can also be used. Examples of such polybasic acids include 5-sodium sulfoisophthalic acid (SIPA-Na), 5-sodium sulfoterephthalic acid (STPA-Na), dimethyl 5-sodium sulfoisophthalate (SIPM-Na), dimethyl 5-sodium sulfoterephthalate (STPM-Na), dimethyl 5-potassium sulfoisophthalate (SIPM-K), dimethyl 5-lithium sulfoisophthalate (SIPM-Li), and the like. Using such polybasic acids in excess will impair the water resistance of the resulting coating film. In the present invention, in the acid component constituting the polyester resin, the polybasic acid is preferably less than 1 mol%, more preferably less than 0.5 mol%, and even more preferably 0 mol%.

[0017] The polyhydric alcohol component constituting the polyester resin is not particularly limited. For example, aliphatic glycols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol; alicyclic glycols such as 1,4-cyclohexanedimethanol, 1,3-cyclobutanedimethanol; ether bond-containing glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, polytetramethylene glycol, polyethylene glycol, polypropylene glycol; polyhydric alcohols with three or more functional groups such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. can be mentioned. Furthermore, alkylene oxide adducts of bisphenols (bisphenol A) such as 2,2-bis[4-(hydroxyethoxy)phenyl]propane and alkylene oxide adducts of bisphenols (bisphenol S) such as bis[4-(hydroxyethoxy)phenyl]sulfone can also be used. These polyhydric alcohol components can be used alone or in combination of two or more kinds.

[0018] Among the above-mentioned polyhydric alcohols, ethylene glycol and neopentyl glycol are preferred. The content of either one or the total content of both of them is preferably 20 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more.

[0019] When using a polyhydric alcohol with three or more functional groups as the polyhydric alcohol, it is preferably 5 mol% or less, and more preferably 3 mol% or less in the polyhydric alcohol component of the polyester resin.

[0020] The acid value of the polyester resin is preferably 3 mg KOH / g or higher, more preferably 3 to 30 mg KOH / g, even more preferably 4 to 20 mg KOH / g, and particularly preferably 5 to 15 mg KOH / g. If the acid value of the polyester resin is less than 3 mg KOH / g, it may be difficult to disperse it in an aqueous medium. Alternatively, even if an aqueous dispersion is obtained, its dispersion stability may be very unstable.

[0021] The number-average molecular weight of the polyester resin is preferably 5,000 to 50,000, more preferably 7,000 to 30,000, even more preferably 8,000 to 25,000, and particularly preferably 9,000 to 20,000. If the number-average molecular weight of the polyester resin is less than 5,000, the adhesion of the resulting coating film may be poor, and if it exceeds 50,000, dispersion in an aqueous medium may be difficult.

[0022] The degree of dispersion (hereinafter referred to as "degree of dispersion") in the molecular weight distribution of polyester resin is preferably 2 to 10, more preferably 2 to 9, and even more preferably 2 to 8. It is difficult to obtain a polyester resin with a degree of dispersion of less than 2, and if the degree of dispersion exceeds 10, the dispersion stability of the aqueous dispersion becomes poor. The degree of dispersion refers to the value obtained by dividing the weight-average molecular weight by the number-average molecular weight.

[0023] (Acid-modified polyolefin resin) The acid-modified polyolefin resin, which contains carboxyl groups, is preferably a copolymer containing an acid-modified component and an olefin component as copolymer components. The acid modification of the polyolefin resin improves the film-forming properties and coatability onto substrates of the coating agent of the present invention.

[0024] The acid-modified component is preferably an unsaturated carboxylic acid component, and is introduced by an unsaturated carboxylic acid or its anhydride. Specific examples of unsaturated carboxylic acid components include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, crotonic acid, as well as half-esters and half-amides of unsaturated dicarboxylic acids. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred, with acrylic acid and maleic anhydride being particularly preferred.

[0025] The content of the acid-modifying component in the acid-modified polyolefin resin is not particularly limited, but is preferably 1 to 40% by mass, more preferably 1 to 30% by mass, and even more preferably 2 to 20% by mass. If the content of the acid-modifying component is less than 1% by mass, the acid-modified polyolefin resin may not be able to disperse stably in an aqueous medium, and if it exceeds 40% by mass, the resulting coating film may have poor adhesion to the substrate.

[0026] Examples of olefin components constituting acid-modified polyolefin resins include alkenes with 2 to 6 carbon atoms, such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, and 1-hexene, and mixtures thereof can also be used. Among these, alkenes with 2 to 4 carbon atoms, such as ethylene, propylene, isobutylene, and 1-butene, are preferred, with ethylene being more preferred.

[0027] In acid-modified polyolefin resins, the olefin component content is preferably 50% by mass or more, and more preferably 70% by mass or more, from the viewpoint of improving durability such as water resistance and oil resistance.

[0028] Acid-modified polyolefin resins preferably contain (meth)acrylic acid ester components to improve adhesion to the substrate. The content of (meth)acrylic acid ester components in the acid-modified polyolefin resin is preferably 0.5 to 40% by mass, more preferably 1 to 35% by mass, even more preferably 3 to 30% by mass, and particularly preferably 5 to 25% by mass.

[0029] Examples of (meth)acrylic acid ester components include esters of (meth)acrylic acid with alcohols having 1 to 30 carbon atoms, and among these, esters of (meth)acrylic acid with alcohols having 1 to 20 carbon atoms are preferred due to their availability. Specific examples of such compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate. Mixtures of these may also be used. Among these, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl acrylate, and octyl acrylate are more preferred from the viewpoint of improving adhesion to the substrate, ethyl acrylate and butyl acrylate are even more preferred, and ethyl acrylate is particularly preferred. Note that "(meth)acrylic acid~" means "acrylic acid~ or methacrylic acid~".

[0030] Furthermore, the acid-modified polyolefin resin may contain other components in an amount of 10% by mass or less of the acid-modified polyolefin resin, in addition to the components mentioned above. Examples of other components include alkenes and dienes having more than 6 carbon atoms, such as 1-octene and norbornene; maleic acid esters such as dimethyl maleate, diethyl maleate, and dibutyl maleate; (meth)acrylamides; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and vinyl versatate; vinyl alcohol obtained by saponifying vinyl esters with basic compounds, etc.; 2-hydroxyethyl acrylate, glycidyl (meth)acrylate, (meth)acrylonitrile, styrene, substituted styrene, carbon monoxide, sulfur dioxide, and mixtures thereof may also be used.

[0031] Furthermore, the acid-modified component constituting the acid-modified polyolefin resin may contain an N-substituted amide structure in which the hydroxyl group of the carboxyl group is replaced with an N,N-dimethylamino group, an N,N-diethylamino group, or the like.

[0032] Examples of acid-modified polyolefin resins include ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid-maleic anhydride copolymer, acid-modified polyethylene, acid-modified polypropylene, acid-modified ethylene-propylene resin, acid-modified ethylene-butene resin, acid-modified propylene-butene resin, acid-modified ethylene-propylene-butene resin, or ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid copolymer obtained by further acrylic modification of these acid-modified resins with (meth)acrylic acid esters, etc. Among these, ethylene-(meth)acrylic acid-maleic anhydride copolymer is preferred. Furthermore, the acid-modified polyolefin resin may be chlorinated in the range of 5 to 40% by mass.

[0033] As acid-modified polyolefin resins, commercially available products such as the Bondine series from Arkema, the Bestplast series from Evonik Japan, the Primacol series from Dow Chemical, the Yumex series from Sanyo Chemical Industries, the Admer series from Mitsui Chemicals, and the Toyo Tac series from Toyobo can be used. In addition, commercially available water-based products can also be used, such as the Superclon series from Nippon Paper Chemicals, the Zaixen series from Sumitomo Seika, the Chemipearl series from Mitsui Chemicals, and the Hardlen series from Toyobo.

[0034] <Carbon-based materials> The coating agent of the present invention contains a carbon-based material for the purpose of improving conductivity. The type of carbon-based material is not particularly limited and includes carbon nanotubes, fullerenes, graphene, carbon fibers, and carbon black, but carbon nanotubes are preferred because they provide high conductivity.

[0035] The type of carbon nanotube is not particularly limited, but examples include single-walled carbon nanotubes and multi-walled carbon nanotubes, and these may be mixed in the present invention. Multi-walled carbon nanotubes are preferred because they have high affinity with resins and even better adhesion.

[0036] The average diameter of the carbon nanotubes is not particularly limited, but is preferably 0.5 to 100 nm, more preferably 0.8 to 50 nm, and even more preferably 1 to 30 nm.

[0037] The average length of the carbon nanotubes is not particularly limited, but is preferably 0.1 to 1000 μm, more preferably 0.2 to 800 μm, and even more preferably 0.5 to 500 μm.

[0038] The carbon-based material is preferably in an amount of 10 to 200 parts by mass, more preferably 15 to 150 parts by mass, and even more preferably 20 to 100 parts by mass, per 100 parts by mass of the resin containing carboxyl groups. If the carbon-based material content is less than 10 parts by mass, the conductivity may be poor, and if it exceeds 200 parts by mass, the adhesion to the substrate may decrease.

[0039] <Metal oxides> The coating agent of the present invention, by simultaneously containing metal oxides and carbon-based materials, exhibits improved transparency compared to coatings containing only carbon-based materials. Furthermore, its solvent resistance is also improved.

[0040] Examples of metal oxides constituting the coating agent of the present invention include tin oxide, antimond-doped tin oxide, tin-doped indium oxide, zinc oxide, titanium oxide, tungsten oxide, molybdenum oxide, and vanadium oxide. Among these, tin oxide, antimond-doped tin oxide, and tin-doped indium oxide are preferred due to their high conductivity. Furthermore, tin oxide is even more preferred from the viewpoint of ease of handling. Tin oxide is preferably used in the form of a dispersion (sol) that has been pre-dispersed in water or a solvent mainly composed of water.

[0041] The shape of the contained metal oxide is, for example, particulate. Its size is not particularly limited, but since transparency increases as the particle size decreases, the average particle size is preferably 200 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less.

[0042] The metal oxide content is preferably 30 to 1500 parts by mass, more preferably 50 to 1200 parts by mass, and even more preferably 100 to 1000 parts by mass, per 100 parts by mass of the resin containing carboxyl groups. If the metal oxide content is less than 30 parts by mass, the transparency may be poor, and if it exceeds 1500 parts by mass, the adhesion to the substrate may decrease.

[0043] <Aqueous medium> The aqueous medium constituting the coating agent of the present invention is water or a liquid mainly composed of water. Using an aqueous medium is preferable from an environmental standpoint, and it also makes it easier to form a thinner film when the coating agent of the present invention is used as a coating film. The aqueous medium may contain basic compounds or hydrophilic organic solvents. The inclusion of hydrophilic organic solvents in the aqueous medium improves the wettability of the coating agent to the substrate, resulting in improved coating properties and film-forming capabilities.

[0044] The hydrophilic organic solvent content is preferably 1 to 50% by mass, more preferably 3 to 30% by mass, and even more preferably 5 to 25% by mass, relative to the total amount of the coating agent, in order to impart appropriate wettability to the substrate.

[0045] Examples of hydrophilic organic solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, and cyclohexanone; ethers such as tetrahydrofuran and dioxane; ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, and 3-methoxy acetate. Examples include esters such as butyl, methyl propionate, ethyl propionate, diethyl carbonate, and dimethyl carbonate; glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and ethylene glycol ethyl ether acetate; and also 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methoxy-3-methyl-1-butanol, methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoethyl acetate, 1,2-dimethylglycerin, 1,3-dimethylglycerin, or trimethylglycerin.

[0046] Examples of basic compounds include ammonia, triethylamine, N,N-dimethylethanolamine, isopropylamine, aminoethanol, dimethylaminoethanol, diethylaminoethanol, ethylamine, diethylamine, isobutylamine, dipropylamine, 3-ethoxypropylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, n-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, 2,2-dimethoxyethylamine, monoethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, pyrrole, or pyridine.

[0047] <Additives> The coating agent of the present invention may contain additives such as crosslinking agents to further improve performance depending on the purpose.

[0048] The crosslinking agent is not particularly limited and includes, for example, self-crosslinking agents, compounds having multiple functional groups that react with carboxyl groups within the molecule, and metals having polyvalent coordination sites. Specifically, isocyanate compounds, melamine compounds, urea compounds, epoxy compounds, carbodiimide compounds, oxazoline group-containing compounds, zirconium salt compounds, and silane coupling agents are preferred. Furthermore, multiple of these crosslinking agents may be used simultaneously.

[0049] The crosslinking agent content is preferably 0.01 to 80 parts by mass, more preferably 0.1 to 50 parts by mass, and even more preferably 0.5 to 30 parts by mass, per 100 parts by mass of the resin containing carboxyl groups. If the crosslinking agent content is less than 0.01 parts by mass, improvement in the performance of the formed coating film tends not to be expected, and if it exceeds 80 parts by mass, performance such as processability may decrease.

[0050] The coating agent of the present invention may further contain various additives as needed, such as surfactants, leveling agents, defoaming agents, anti-wrinkle agents, pigment dispersants, ultraviolet absorbers, weathering agents, and flame retardants.

[0051] The coating agent of the present invention contains a resin containing carboxyl groups, a carbon-based material, a metal oxide, and an aqueous medium, wherein the resin containing carboxyl groups is preferably dispersed in the aqueous medium. The content of nonvolatile components in the coating agent of the present invention can be appropriately selected depending on the coating conditions, the desired thickness and performance of the coating film, etc., and is not particularly limited, but in terms of maintaining an appropriate viscosity and exhibiting good film-forming properties, it is preferably 1 to 60% by mass, more preferably 3 to 55% by mass, even more preferably 5 to 50% by mass, and particularly preferably 10 to 45% by mass.

[0052] From the viewpoint of coatability on a substrate, the viscosity of the coating agent of the present invention is preferably 1 to 2000 mPa·s, more preferably 3 to 1000 mPa·s, and even more preferably 5 to 500 mPa·s.

[0053] The method for producing the coating agent of the present invention is not particularly limited, and includes mixing the above-mentioned raw materials, in which order of mixing is arbitrary. The resin containing carboxyl groups may be mixed in the form of an aqueous dispersion dispersed in an aqueous medium.

[0054] <coating film> The coating agent of the present invention can be applied to a substrate such as a film or nonwoven fabric using known coating methods to form the coating film of the present invention. For example, by uniformly applying the coating to the substrate surface using methods such as gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dipping coating, or brush application, and then subjecting it to a heat treatment for drying, a uniform coating film can be formed and adhered to the substrate surface. As a heating device, a conventional hot air circulation type oven or infrared heater can be used. The heating temperature and heating time can be appropriately selected considering economic efficiency and other factors.

[0055] The coating film of the present invention preferably has a thickness of 0.05 to 20 μm, more preferably 0.08 to 10 μm, and even more preferably 0.1 to 5 μm. A coating film formed to have a thickness within the above range exhibits excellent uniformity of thickness. Furthermore, since the coating film of the present invention exhibits excellent conductivity even as a thin film, it is possible to achieve both conductivity and transparency.

[0056] To adjust the thickness of the coating film, it is preferable to appropriately select the equipment and operating conditions used for coating, as well as to use a coating agent with a concentration suitable for the desired thickness. The concentration of the coating agent can be adjusted by the composition of the mixture during preparation, or it may be adjusted by appropriately diluting or concentrating the prepared coating agent.

[0057] <Laminate> The laminate of the present invention includes the coating film of the present invention, and examples include laminates in which the coating film of the present invention is included on the surface of various substrates, an adhesive layer, or a primer layer. The laminate of the present invention can be used, for example, in packaging materials for semiconductors and electronic components, semiconductor elements, surface protection films, removable labels, carrier tapes, masking tapes, polarizing plates, transparent touch panels and displays, light-emitting diodes, magnetic recording materials, electrophotographic recording materials, magnetic tapes, solar cells, secondary batteries, fuel cells, computer components, mobile phone components, automotive components, and the like. [Examples]

[0058] The present invention will be specifically described below with reference to examples. However, the present invention is not limited thereto. Various characteristics were measured or evaluated using the following methods.

[0059] 1. Surface resistivity (conductivity) of the laminate In accordance with JIS K6911, the surface resistivity of the coating film surface of the laminate was measured using a digital ultra-high resistance / micro-current meter (Advantest R8340 model) at a temperature of 20°C and a humidity of 60% RH, and the conductivity was evaluated according to the following criteria. ◎: Surface resistivity is 1 × 10⁻⁶ 6 Ω / □ or less ○: Surface resistivity is 1 × 10⁻⁶ 6 Ω / □ exceeding 1×10 8 Ω / □ or less △: Surface resistivity is 1 × 10⁻⁶ 8 Ω / □ exceeding 1×10 9 Ω / □ or less ×: Surface resistivity is 1 × 10 9 Ω / □ exceeding

[0060] 2. Total light transmittance (transparency) of the laminate The total light transmittance of the laminate was measured using a turbidimeter (NDH2000 model, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7361-1. Air was used as the background for the measurement. The total light transmittance of the substrate was 90%. Transparency was evaluated according to the following criteria. ◎: Total light transmittance 80% or more ○: Total light transmittance of 75% or more and less than 80% △: Total light transmittance 70% or more but less than 75% ×: Total light transmittance less than 70%

[0061] 3. Solvent resistance of the laminate The laminate was immersed in toluene at 20°C for 1 hour. After the treated laminate was thoroughly dried, the solvent resistance was evaluated by visual inspection for changes in appearance (peeling) and measurement of surface resistivity according to the following criteria. ○: No change in the coating, and the increase in surface resistivity is less than 10 times. △: No change in the coating, but the surface resistivity increases by more than 10 times. ×: The paint film peels off.

[0062] 4. Evaluation of coating adhesion Adhesion tests were conducted on the coating surface of the laminate according to the method of JIS K5400 8.5.2. The coating was cut to create 100 grid sections of 1 mm x 1 mm, and these were peeled off using adhesive tape. The number of sections that remained intact within the 100 grid sections was counted, and the adhesion of the coating was evaluated according to the following criteria. ◎: 100 〇:95 or more and 99 or less △: 85 or more and 94 or less ×: 84 or less

[0063] The following materials were used as raw materials and substrates for the coating agent.

[0064] 1. Polyester resin Production of aqueous dispersion of polyester resin (A-1) [Preparation of polyester resin (a1)] A mixture consisting of 2077g terephthalic acid, 2077g isophthalic acid, 1102g ethylene glycol, and 1666g neopentyl glycol was heated in an autoclave at 240°C for 4 hours to carry out an esterification reaction. Next, 3.3g of zinc acetate was added as a catalyst, the temperature of the system was raised to 265°C, and the pressure of the system was gradually reduced to 13 Pa after 1.5 hours. Under these conditions, the polycondensation reaction was continued, and after 4 hours the system was brought to atmospheric pressure with nitrogen gas, the temperature of the system was lowered to 260°C, and 29g of trimellitic anhydride was added. The mixture was stirred at 260°C for 2 hours to carry out a depolymerization reaction. After that, the pressure of the system was gradually reduced to 13 Pa after 0.5 hours, and degassing was performed for 1 hour. Next, the system was pressurized with nitrogen gas, the resin was discharged in strand form, cooled with water, and cut to obtain pellet-shaped (approximately 3mm in diameter and 3mm in length) polyester resin (a1).

[0065] [Dissolution process] 400 g of polyester resin (a1) and 600 g of methyl ethyl ketone were placed in a 3 L polyethylene container, and the mixture was heated and stirred until the system temperature reached approximately 60°C, completely dissolving the polyester resin (a1) in the methyl ethyl ketone to obtain a polyester resin (a1) solution with a solid content concentration of 40% by mass.

[0066] [Phase inversion emulsification process] 500 g of the polyester resin (a1) solution was placed in a jacketed glass container (capacity 2 L), and the mixture was stirred while maintaining the system temperature at 13°C. 22.7 g of triethylamine was added as a basic compound. Subsequently, 477.3 g of distilled water at 13°C was added at a rate of 100 g / min, and stirring was continued for 30 minutes. The system temperature remained below 15°C throughout the entire addition of distilled water. After the addition of distilled water was complete, an aqueous dispersion with a solid content of 20% by mass was obtained.

[0067] [Solvent removal process] 800 g of the obtained polyester resin (a1) dispersion and 52.3 g of distilled water were placed in a 2 L round-bottom flask, and desolvation was carried out under reduced pressure while adjusting the internal temperature to 50°C or lower. Desolvation was stopped when the amount removed by distillation reached approximately 360 g, and after cooling to room temperature, the mixture was filtered through a 300 mesh stainless steel filter. Next, the solid content concentration of this aqueous dispersion was measured, and then distilled water was added to bring the solid content concentration to 30% by mass to obtain the aqueous dispersion of polyester resin (A-1).

[0068] 2. Acid-modified polyolefin resin Production of an aqueous dispersion of acid-modified polyolefin resin (B-1) Using a stirrer equipped with a sealed, pressure-resistant 1-liter glass container with a heater, 60.0 g of polyolefin resin (ethylene-ethyl acrylate-maleic anhydride copolymer, 6% by mass of ethyl acrylate, 2% by mass of maleic anhydride, melting point 105°C, glass transition temperature less than 0°C), 75.0 g of isopropanol (hereinafter referred to as IPA), 3.9 g of N-dimethylethanolamine (hereinafter referred to as DMEA) (1.0 equivalent relative to the carboxyl groups of maleic anhydride in the resin), and 161.1 g of distilled water were placed in the glass container, and the mixture was stirred at a rotation speed of 300 rpm. No sedimentation of resin granules was observed at the bottom of the container, and it was confirmed that the mixture was suspended. Maintaining this state, the heater was turned on after 10 minutes to heat the mixture. The system temperature was then maintained at 140°C and the mixture was stirred for a further 30 minutes. Subsequently, the mixture was cooled to room temperature (approximately 25°C) by air cooling while stirring at a rotation speed of 300 rpm. Then, it was pressure filtered (air pressure 0.2 MPa) through a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave). 250 g of the resulting aqueous dispersion and 90 g of distilled water were placed in a 0.5-liter two-necked round-bottom flask. A mechanical stirrer and a Liebig condenser were installed, and the flask was heated in an oil bath to remove the aqueous medium by distillation. After removing approximately 90 g of the aqueous medium, heating was stopped, and the mixture was cooled to room temperature. After cooling, the liquid components in the flask were pressure filtered (air pressure 0.2 MPa) through a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave) to obtain a milky white, homogeneous polyolefin resin aqueous dispersion (B-1).

[0069] 3. Acrylic resin Aqueous dispersion of acrylic resin (C-1): Manufactured by Saiden Chemical Co., Ltd., EK-61, solid content concentration 40% by mass.

[0070] 4. Metal oxides Tin oxide sol: 0.1 moles of stannic chloride pentahydrate were dissolved in 200 ml of water to make a 0.5 M aqueous solution. While stirring, 28% aqueous ammonia was added to obtain a pH 1.5 white slurry containing ultrafine tin oxide particles. The obtained slurry containing ultrafine tin oxide particles was heated to 70°C, then allowed to cool naturally to around 50°C. Pure water was added to obtain 1 L of slurry containing ultrafine tin oxide particles, and solid-liquid separation was performed using a centrifuge. 800 ml of pure water was added to this aqueous solid, and after stirring and dispersion using a homogenizer, solid-liquid separation was performed using a centrifuge to wash the mixture. 75 ml of pure water was added to the washed aqueous solid to prepare a slurry containing ultrafine tin oxide particles. 3.0 ml of triethylamine was added to the obtained slurry containing ultrafine tin oxide particles and stirred. When it became transparent, the temperature was raised to 70°C, then heating was stopped and it was allowed to cool naturally to obtain a tin oxide sol with a solid content of 10.5% by mass, using an organic amine as a dispersion stabilizer.

[0071] Antimond-doped tin oxide (ATO): Manufactured by Ishihara Sangyo Co., Ltd., SN-100D, solid content concentration 30% by mass.

[0072] 5. Carbon-based materials Multiwalled carbon nanotubes: aqueous dispersion, manufactured by Nippon Shizai Co., Ltd., solid content concentration 3.0% by mass. Single-walled carbon nanotube: aqueous dispersion, manufactured by Nippon Shizai Co., Ltd., solid content concentration 0.1% by mass Graphene: Aqueous dispersion, manufactured by Nishina Material Co., Ltd., solids content concentration 20% by mass

[0073] 6. Film substrate Unitika Corporation, 50μm PET film, total light transmittance 90%

[0074] Example 1 A coating agent was prepared by adding 76.5 g of tin oxide sol and 19.7 g of a multi-walled carbon nanotube aqueous dispersion to 3.8 g of a polyester resin aqueous dispersion (solid content mass ratio 100 / 600 / 50). The prepared coating solution was applied to a film substrate using a bar coater so that the coating thickness after drying would be 0.1 μm. The coating film was then formed by drying in a hot air dryer set to 100°C for 60 seconds, and a laminate was fabricated.

[0075] Examples 2~12、14、16~25、27 Comparative Examples 1-4 , Reference examples 1~4 As shown in Tables 1 and 2, coating agents were prepared by changing the type of resin, metal oxide, or carbon-based material, or the mass ratio (content) of each solid, and laminates were fabricated in the same manner as in Example 1.

[0076] Tables 1 and 2 show the composition of the coating agents prepared in the examples and comparative examples, as well as the evaluation results of their various properties.

[0077] [Table 1]

[0078] [Table 2]

[0079] Each example The coating film formed using the obtained coating agent, by incorporating a combination of carbon-based materials and metal oxides, was able to improve transparency while maintaining conductivity. Furthermore, the inclusion of metal oxides resulted in a coating film with excellent solvent resistance.

[0080] In Comparative Examples 1 and 3, the coatings formed with coating agents that did not contain metal oxides had lower transparency than those in the Examples. Furthermore, in Comparative Examples 2 and 4, the coatings formed with coating agents that did not contain carbon-based materials had lower conductivity than those in the Examples.

Claims

1. A coating agent comprising a resin containing carboxyl groups, a carbon-based material, a metal oxide, and an aqueous medium, wherein the resin containing carboxyl groups is an acid-modified polyolefin resin and / or a polyester resin, the carbon-based material is a carbon nanotube, and the metal oxide is tin oxide.

2. The coating agent according to claim 1, wherein the carbon-based material content is 10 to 200 parts by mass per 100 parts by mass of the resin containing carboxyl groups.

3. The coating agent according to claim 1 or 2, wherein the content of the metal oxide is 30 to 1500 parts by mass per 100 parts by mass of the resin containing carboxyl groups.

4. A coating film comprising the coating agent described in any one of claims 1 to 3.

5. A laminate comprising the coating film described in claim 4.

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