Conductive tape using oxygen and moisture barrier coating composition

Abstract

The present invention relates to a conductive tape for electromagnetic shielding comprising a coating layer using an oxygen and moisture permeability-preventing coating composition. Specifically, by modifying the polyvinyl alcohol included in the coating composition with carboxyl groups, the invention relates to a conductive tape that exhibits excellent oxygen and moisture permeability-preventing performance and can shield electromagnetic waves from various display panels, high-speed information communication devices, electronic devices, and various electronic equipment.

Description

Technology Field

[0001] The present invention relates to a conductive tape using an oxygen and moisture permeability-preventing coating composition, and specifically, to a conductive tape capable of shielding electromagnetic waves of various display panels, high-speed information communication devices, electronic devices, and various electronic equipment by modifying the polyvinyl alcohol included in the coating composition.

[0002] This invention is the result of research supported by the following research and development project.

[0003] Project Title: Development / Commercialization Support for Stacked Organic Electronic Materials and Thin-Film Devices

[0004] Research Project ID: GRRCDankook2022-B01

[0005] Supervising Ministry: Gyeonggi-do

[0006] Research Project Name: Gyeonggi Regional Cooperation Research Center (GRRC) Support Project

[0007] Lead Organization and Research Management Agency: Gyeonggi Regional Cooperation Research Center Background Technology

[0008] Electromagnetic waves generated on the circuits of electronic devices can, in some cases, cause disruption to the functions of surrounding electronic devices or components, degrade performance, shorten the lifespan of electronic devices, or damage electronic images. Therefore, conductive tapes can be used to shield electromagnetic waves from various electronic devices, including display panels and high-speed information communication devices.

[0009] A conductive tape can be manufactured by coating a conductive adhesive onto a conductive substrate including conductive fibers, metal foils, conductive nonwoven fabrics, etc., and the conductive tape has excellent electrical conductivity, resulting in a significant electromagnetic shielding effect. In addition, the conductive tape can be in the form of a single-sided or double-sided adhesive tape, and has the advantage of being able to be processed into various shapes depending on the application.

[0010] Electromagnetic shielding of conductive tapes is primarily achieved through a conductive substrate, and a conductive adhesive layer is manufactured by coating a conductive adhesive on one side of the conductive substrate to provide adhesion. The conductive adhesive is prepared by adding a conductive filler containing carbon black, graphite, graphene, silver, copper, nickel, aluminum, etc., to an adhesive polymer resin, thereby forming continuous conductive paths within the conductive adhesive layer, which imparts conductivity to the conductive adhesive layer and enables efficient electromagnetic shielding. However, since the electromagnetic shielding efficiency decreases when this conductive filler comes into contact with oxygen, a technology capable of blocking oxygen is required.

[0011] In the case of adhesives, acrylic copolymers are generally used as adhesive polymer resins, and the adhesive strength of the adhesive is controlled by adjusting the type and content of polar monomers in the acrylic copolymer. Generally, adhesives are manufactured using monomers containing carboxylic acids as polar monomers. However, Korean Patent Application No. 10-2017-0059356 confirmed that conductive tapes containing an adhesive layer manufactured using an acrylic copolymer containing carboxylic acids have limitations in terms of long-term stability of the adhesive layer in high-moisture environments, as metal ions contained in the conductive substrate layer migrate to the adhesive layer due to moisture and react with the carboxylic acids contained in the adhesive layer, causing a decrease in the adhesive strength of the adhesive layer.

[0012] Meanwhile, according to the prior art, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), or paper (release paper), which is inexpensive in terms of unit cost, is used as a release film protecting the adhesive layer. In this case, to improve the moisture and oxygen barrier properties of the release film, the coating solution composition includes ethylene vinyl alcohol, polyvinyl alcohol, polyvinylidene chloride, polyamide, etc., to block oxygen and moisture. Recently, as there is a demand for eco-friendly coatings capable of biodegradation or alkali degradation, polyvinyl alcohol is used as a material for the moisture and oxygen barrier coating layer; however, there have been difficulties in its use due to its high oxygen permeability and low moisture barrier properties. [Patent No. 10-2015-0073408]

[0013] Accordingly, there is a demand for a coating composition that is environmentally friendly and capable of blocking oxygen and moisture by modifying polyvinyl alcohol. The problem to be solved

[0014] The technical problem to be solved by the present invention is to provide a conductive tape for electromagnetic shielding comprising a coating composition that solves the problem of reduced adhesive strength of the adhesive layer due to reaction with a carboxylic acid contained in the conductive adhesive layer during the process in which metal ions move from the conductive substrate layer to the adhesive layer by moisture, and the problem of oxidation of the conductive filler contained in the conductive adhesive layer by oxygen.

[0016] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0017] One embodiment of the present invention provides a conductive tape for electromagnetic shielding comprising a conductive substrate layer, an adhesive layer located on at least one surface of the conductive substrate layer, and a release film layer located on the adhesive layer, wherein the conductive tape for electromagnetic shielding is formed from a coating composition comprising a carboxyl group-modified polyvinyl alcohol solution, a metallic crosslinking agent, and an antifoaming agent, and further comprises a coating layer located on at least one of at least one surface of the conductive substrate layer and at least one surface of the release film layer. Effects of the invention

[0018] A conductive tape according to one embodiment of the present invention can improve long-term stability by blocking moisture and oxygen.

[0019] The effects of the present invention are not limited to those described above, and unmentioned effects will be clearly understood by those skilled in the art from the present specification and the accompanying drawings. Brief explanation of the drawing

[0020] FIG. 1 is a schematic diagram of a conductive tape comprising a coating layer manufactured using a coating composition according to one embodiment of the present invention. Specific details for implementing the invention

[0021] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0022] Throughout this specification, when a component is described as being located "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0023] Throughout the entire specification, the unit "parts by weight" may refer to the ratio of weight between each component.

[0024] Throughout this specification, "(meth)acrylate" is used to refer collectively to acrylates and methacrylates.

[0025] Throughout this specification, "A and / or B" means "A and B, or A or B".

[0026] The present invention will be described in more detail below.

[0028] One embodiment of the present invention provides a conductive tape for electromagnetic shielding comprising a conductive substrate layer, an adhesive layer located on at least one surface of the conductive substrate layer, and a release film layer located on the adhesive layer, wherein the conductive tape for electromagnetic shielding is formed from a coating composition comprising a carboxyl group-modified polyvinyl alcohol solution, a metallic crosslinking agent, and an antifoaming agent, and further comprises a coating layer located on at least one of at least one surface of the conductive substrate layer and at least one surface of the release film layer.

[0029] A conductive tape according to one embodiment of the present invention can improve long-term stability by blocking moisture and oxygen.

[0031] FIG. 1 is a schematic diagram of a conductive tape comprising a coating layer manufactured using a coating composition according to one embodiment of the present invention.

[0032] As shown in FIG. 1, the conductive tape is composed of a conductive substrate layer, an adhesive layer, and a release film layer, and may be in the form of a single-sided or double-sided tape.

[0033] (a) is a general form of a single-sided conductive tape, wherein the coating layer may be formed on at least one surface of a release film layer and / or a conductive substrate layer, and when the coating layer is located on one surface of the release film layer, the other surface of the release film layer may further include a silicone coating layer, and when the coating layer is located on at least one surface of the conductive substrate layer, the coating layer may further include a conductive filler.

[0034] (b) is a general form of a double-sided conductive tape, wherein a coating layer may be formed on at least one surface of a release film layer and / or a conductive substrate layer, and when the coating layer is located on one surface of the release film layer, the other surface of the release film layer may further include a silicone coating layer, and when the coating layer is located on at least one surface of the conductive substrate layer, the coating layer may further include a conductive filler.

[0036] According to one embodiment of the present invention, the conductive substrate layer may include one or more selected from conductive fibers, metal foils, and conductive nonwoven fabrics, but is not limited thereto.

[0037] According to one embodiment of the present invention, the adhesive layer is located on at least one surface of the conductive substrate layer, and the type of adhesive for forming the adhesive layer is not particularly limited, and examples include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, epoxy adhesives, fluorine adhesives, etc. In addition, adhesives generally used in conductive tapes may be included, and the adhesives known above may be used alone or in combination of two or more types.

[0039] According to one embodiment of the present invention, the adhesive may include a crosslinking agent, and the type of crosslinking agent is not particularly limited, and examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelating curing agents, etc. In addition, it may include generally used crosslinking agents, and the crosslinking agents known above may be used alone or in combination of two or more types. As described above, by adding a crosslinking agent to the adhesive, the cohesive force of the adhesive layer can be controlled.

[0041] According to one embodiment of the present invention, the adhesive may include a flame retardant, and the type of flame retardant is not particularly limited, and examples include halogen-based and non-halogen-based flame retardants. In addition, it may include generally used flame retardants, and the flame retardants known above may be used alone or in combination of two or more types. As described above, by adding a flame retardant to the adhesive, the flame retardancy and heat resistance of the adhesive layer can be controlled.

[0042] According to one embodiment of the present invention, the release film layer located on the adhesive layer may comprise one or more of polyethylene terephthalate, polyethylene, polypropylene, and paper. When the adhesive layer is located on both sides of a conductive substrate layer, the release film layer may also be located on both adhesive layers.

[0044] According to one embodiment of the present invention, the carboxyl group modified polyvinyl alcohol included in the coating composition forming a coating layer located on at least one surface of the release film layer may be produced by reacting an aqueous solution of polyvinyl alcohol with one or more of a polycarboxylic acid derivative, a carboxylic acid anhydride, an aldehyde derivative containing a carboxyl group, and an acrylic acid derivative containing a carboxyl group.

[0046] According to one embodiment of the present invention, the carboxyl group modified polyvinyl alcohol may comprise a repeating unit represented by the following chemical formula 1 and a repeating unit represented by the following chemical formula 2.

[0047] [Chemical Formula 1]

[0048]

[0049] [Chemical Formula 2]

[0050]

[0051] The above R1 may include 1 to 10 directly connected alkyl groups that are straight-chain or branched-chain alkyl groups having 1 to 10 carbon atoms, or aromatic hydrocarbons or aliphatic hydrocarbons having 1 to 20 carbon atoms, and the above “*” indicates a connection point.

[0052] As described above, by implementing the carboxyl group modified polyvinyl alcohol by including a repeating unit represented by Chemical Formula 1 and a repeating unit represented by Chemical Formula 2, a coating layer can be formed in a short time by performing crosslinking with a metallic crosslinking agent.

[0054] According to one embodiment of the present invention, polyvinyl alcohol may be used as fully saponified or partially saponified polyvinyl alcohol, and copolymerized polyvinyl alcohol such as ethylene may be used. Specifically, the polyvinyl alcohol may be commercially manufactured by DowDuPont, Eastman Chemical, Japan Synthetic Chemical Industry, Celanese Corporation, OCI Corp., Solutia Corp., Sinopec Group, Kuraray, Sekisui Chemical Corp., Changzheng Petrochemical Co., Ltd., VAM & Poval Japan, Sekisui Chemical Corp., Merck KGaA, Anhui Wanwei Group, and other companies, and various grades of polyvinyl alcohol may be used. More specifically, there are various grades of polyvinyl alcohol classified according to viscosity, degree of saponification, ASH (MAX%), Volatile (MAX%), and pH, such as POLINOL P05, P17, P20, P24, F17, CL05A, and M17 of OCI Inc., and polyvinyl alcohol product families classified according to form, such as EXCEVAL, POVAL, ELVANOL, and MOWIFLEX of Curaray, and various grades of polyvinyl alcohol subdivided within those product families according to viscosity, degree of saponification, ASH (MAX%), Volatile (MAX%), pH, etc., can be used.

[0056] According to one embodiment of the present invention, the solvent used in the reaction in which the carboxyl group-modified polyvinyl alcohol is produced may be water. By selecting the solvent used in the reaction as described above, an environmentally friendly process can be implemented.

[0057] According to one embodiment of the present invention, the water content may be 500 parts by weight or more and 1900 parts by weight or less per 100 parts by weight of the polyvinyl alcohol. By controlling the water content within the above-described range, the drying speed can be controlled.

[0059] According to one embodiment of the present invention, the carboxyl group-modified polyvinyl alcohol may be produced by reacting an aqueous solution of polyvinyl alcohol with a polycarboxylic acid derivative. Specifically, the polycarboxylic acid derivative comprises one or more compounds selected from cyclic or acyclic aliphatic or aromatic compounds having two or more carboxyl groups, such as dicarboxylic acids, tricarboxylic acids, or tetracarboxylic acids. The polycarboxylic acid derivative may also comprise a sulfate group or a phosphate group.

[0060] The above dicarboxylic acid derivative may be an alkane derivative having 2 to 20 carbon atoms including ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, etc., a benzene derivative including benzene-1,2-dicarboxylic acid, benzene-1,3-dicarboxylic acid, benzene-1,4-dicarboxylic acid, etc., or a carboxylic acid derivative of a cycloalkane having 2 to 20 carbon atoms including one or more of 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.

[0061] The above tricarboxylic acid derivative may include one or more of Citric acid (2-hydroxypropane-1,2,3-tricarboxylic acid), Isocitric acid (1-hydroxypropane-1,2,3-tricarboxylic acid), Aconitic acid (Prop-1-ene-1,2,3-tricarboxylic acid), Propane-1,2,3-tricarboxylic acid, Agaric acid (2-Hydroxynonadecane-1,2,3-tricarboxylic acid), Trimesic acid, and benzene-1,3,5-tricarboxylic acid.

[0063] According to one embodiment of the present invention, the carboxyl group-modified polyvinyl alcohol may be produced by reacting an aqueous solution of polyvinyl alcohol with a carboxylic acid anhydride. Specifically, the carboxyl group-modified polyvinyl alcohol may be a reaction product produced by the esterification reaction of an aqueous solution of polyvinyl alcohol with a carboxylic acid anhydride. As described above, by producing the carboxyl group-modified polyvinyl alcohol by reacting with a carboxylic acid anhydride, not only is a carboxyl functional group introduced, but the viscosity, degree of crosslinking, and water resistance of the carboxyl group-modified polyvinyl alcohol can also be controlled.

[0064] According to one embodiment of the present invention, the carboxylic acid anhydride may be a cyclic carboxylic acid anhydride and a derivative thereof. The carboxylic acid anhydride may refer to a compound having a cyclic aliphatic or cyclic aromatic structure or having one or more rings. Specifically, the carboxylic acid anhydride derivative may include an anhydride forming a saturated or unsaturated ring, an anhydride having one or more branches substituted with carbon, carbon chains and other elements in the ring, and a carboxylic acid anhydride having one or more rings in a continuous or branched manner. More specifically, anhydrides forming a saturated or unsaturated ring may include succinic anhydride, glutaric anhydride, and maleic anhydride; anhydrides having one or more branches substituted with carbon, carbon chains, and other elements in the ring may include 2,3-dimethylmaleic anhydride, hexafluoroglutaric anhydride, and allylsuccinic anhydride; and carboxylic anhydrides having one or more rings in a continuous or branched manner may include phthalic anhydride, hexahydrophthalic anhydride, naphthalic anhydride, and phenylmaleic anhydride. It may include 3,3-tetramethyleneglutaric anhydride. By selecting the carboxylic acid anhydride and its derivatives from the above, the side chains of the polyvinyl alcohol can be modified to carboxyl groups, and by modifying to carboxyl groups, it can be implemented to enable thermal crosslinking through a subsequent ionic crosslinking reaction.

[0065] According to one embodiment of the present invention, an acid catalyst or a base catalyst may be additionally added during the reaction between the polyvinyl alcohol aqueous solution and the carboxylic acid anhydride. As described above, by additionally adding an acid catalyst or a base catalyst during the reaction between the polyvinyl alcohol aqueous solution and the carboxylic acid anhydride, the reaction between the polyvinyl alcohol aqueous solution and the carboxylic acid anhydride can be promoted.

[0066] According to one embodiment of the present invention, the acid catalyst may comprise one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, hydrobromide, perchloric acid, hydroiodide, trifluoroacetic acid, glycolic acid, methanesulfonic acid, and toluenesulfonic acid. By selecting the type of acid catalyst as described above, the reaction between the aqueous polyvinyl alcohol solution and the carboxylic acid anhydride can be promoted.

[0068] According to one embodiment of the present invention, the carboxyl group-modified polyvinyl alcohol may be produced by reacting an aqueous polyvinyl alcohol solution with an aldehyde derivative containing a carboxyl group. Specifically, the carboxyl group-modified polyvinyl alcohol may be a reaction product produced by acetalization of an aqueous polyvinyl alcohol solution with an aldehyde derivative containing a carboxyl group. As described above, by using the carboxyl group-modified polyvinyl alcohol as a reaction product of an aqueous polyvinyl alcohol solution with an aldehyde derivative containing a carboxyl group, the acetalization reaction can be carried out at a relatively low temperature, and in addition to introducing a carboxylic acid functional group, an acetalization reaction can be performed with an aldehyde derivative containing an alkyl group, which will be described later, to control the viscosity and degree of crosslinking of the carboxyl group-modified polyvinyl alcohol and to impart water resistance.

[0069] According to one embodiment of the present invention, the aldehyde derivative containing a carboxyl group may be a derivative having an aldehyde group and a carboxyl group at the terminal end of an aliphatic compound. The aliphatic compound may refer to a cyclic aliphatic compound or an acyclic aliphatic compound, or a compound having an aliphatic side chain. Specifically, the aldehyde derivative containing a carboxyl group may be one selected from 2-oxoacetic acid, 3-oxopropanoic acid, 4-oxobutanoic acid, 2-fomylbutanoic acid, glyoxylic acid, and combinations thereof. By selecting the aldehyde derivative containing a carboxyl group from the above, the side chain of the polyvinyl alcohol can be modified with a carboxyl group, and the coating process can be implemented to be suitable for a roll-to-roll process through an ionic crosslinking reaction by modifying with a carboxyl group.

[0071] According to one embodiment of the present invention, the carboxyl group-modified polyvinyl alcohol may be produced by reacting an aqueous polyvinyl alcohol solution with an acrylic acid derivative containing a carboxyl group. Specifically, the carboxyl group-modified polyvinyl alcohol may be a reaction product produced by a radical reaction of an aqueous polyvinyl alcohol solution with a compound containing an acrylic acid derivative containing a carboxyl group. As described above, by using the carboxyl group-modified polyvinyl alcohol as a reaction product of a mixture containing an aqueous polyvinyl alcohol solution and an acrylic acid derivative containing a carboxyl group, the radical reaction can be implemented at a relatively low temperature, and not only can carboxylic acid functional groups be introduced, but the viscosity, degree of crosslinking, and water resistance of the carboxyl group-modified polyvinyl alcohol solution can also be controlled.

[0072] According to one embodiment of the present invention, the acrylic acid derivative containing the carboxyl group may be a derivative having a (meth)acryl group and a carboxyl group at the terminal end of the aliphatic compound. The aliphatic compound may mean a cyclic aliphatic compound or a non-cyclic aliphatic compound, or a compound having an aliphatic side chain. Specifically, the acrylic acid derivative containing the carboxyl group may be a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms, such as methyl acrylic acid, ethyl acrylic acid, 1-propyl acrylic acid, 1-butyl acrylic acid, 2-propyl acrylic acid, 2-butyl acrylic acid, and t-butyl acrylic acid, or an aromatic group, such as 2-phenylacrylic acid and 3-phenyl acrylic acid. By selecting the acrylic acid derivative containing the carboxyl group from the above, the side chain of the polyvinyl alcohol can be modified to a carboxyl group, and the speed of the adhesive process can be improved through an ionic crosslinking reaction by modifying to the carboxyl group.

[0074] According to one embodiment of the present invention, the carboxyl group-modified polyvinyl alcohol is dried after the production reaction to form a solid, and then dissolved in water to form a carboxyl group-modified polyvinyl alcohol solution. At this time, the solid content of the carboxyl group-modified polyvinyl alcohol in the carboxyl group-modified polyvinyl alcohol solution may be 2% by weight or more and 8% by weight or less, 3% by weight or more and 7% by weight or less, or 4% by weight or more and 6% by weight or less. By controlling the solid content of the carboxyl group-modified polyvinyl alcohol described above, the viscosity and drying speed of the coating layer can be controlled.

[0076] By introducing carboxyl groups into the polyvinyl alcohol chain, it becomes possible to realize a structure capable of binding with various metal ions while simultaneously achieving effective ionic crosslinking.

[0077] According to one embodiment of the present invention, the carboxyl group-modified polyvinyl alcohol may be capable of thermal crosslinking (self-esterification). Specifically, it may be capable of metal chelate-type crosslinking using a metallic crosslinking agent to be described later. Through this, the deterioration of oxygen and moisture barrier properties can be prevented.

[0079] According to one embodiment of the present invention, the coating composition comprises a metallic crosslinking agent. By including the metallic crosslinking agent, the carboxyl group-modified polyvinyl alcohol is crosslinked to maintain the oxygen barrier effect of general polyvinyl alcohol while simultaneously improving moisture barrier properties, and an eco-friendly manufacturing process can be implemented during the coating process.

[0080] According to one embodiment of the present invention, the metallic crosslinking agent may include a metal cation with a valence of 2 or higher. Specifically, the metallic crosslinking agent may include a metal such as calcium or magnesium that reacts with water in an aqueous solution to form a metal hydroxide, a metal nitride, a metal carbide, a metal oxide, or a metal derivative including an organometallic amine having an amine group and a metal chelate, an organometallic salt, or an inorganic metal salt. As described above, by including a metal cation with a valence of 2 or higher, the toxicity associated with the metallic crosslinking agent can be reduced.

[0081] According to one embodiment of the present invention, the metal cation is Be 2+ , B 3+ , Mg 2+ , Al 3+ , Si 4+ , Ca 2+ , Sc 2+ , Ti 4+ , V 5+ , Cr 6+ , Mn2+ , Fe 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Ga 3+ , Ge 4+ , As 5+ , Sr 2+ , Y 3+ , Zr 4+ , Nb 5+ , Mo 6+ , Tc 5+ , Ru 6+ , Rh 6+ , Pd 4+ , Ag + , Cd 2+ , In 3+ , Sn 4+ , Sb 5+ , Te 6+ , Ba 2+ , Hf 4+ , Ta 5+ , W 6+ , Re 7+ , Os 6+ , Ir 6+ , Pt 2+ , Au + , Tl 3+ , Pb 4+ , Bi 5+ and Ra 2+ It may include one or more of the following. Specifically, the metal cation is Al 3+ , Ca 2+ , Fe 2+ and Fe 3+ It is preferable to have at least one of the following. By selecting the type of metal cation from the above, it is possible to reduce the toxicity associated with the metallic crosslinking agent, lower manufacturing costs, and improve ease of use.

[0082] According to one embodiment of the present invention, the metal included in the metallic crosslinking agent may be used in the form of a neutral ion source. Specifically, the metal may be an inorganic calcium salt or an organic calcium salt. More specifically, in the case of calcium, the form of a neutral ion source may include inorganic calcium salts such as calcium carbonate, calcium oxide, calcium hydroxide, calcium hydrogen phosphate, calcium nitrate, and calcium chloride, and various organic calcium salts such as calcium acetate, calcium lactate, calcium gluconate, calcium citrate, and calcium propionate. More preferably, the calcium source is preferably calcium carbonate, calcium oxide, calcium hydroxide, calcium chloride, calcium lactate, calcium citrate, calcium gluconate, calcium monophosphate, calcium diphosphate, calcium triphosphate, 5'-ribonucleotide calcium, calcium carboxymethylcellulose, calcium chitosan, etc.

[0083] According to one embodiment of the present invention, among the calcium ion sources, the calcium hydroxide and calcium carbonate, etc. are basic and have extremely low solubility in water, but can be dissolved by the acidic component of the carboxyl group-modified polyvinyl alcohol and can perform the role of neutralization.

[0084] According to one embodiment of the present invention, inorganic calcium salts or organic calcium salts other than calcium hydroxide and calcium carbonate have the highest solubility in water at 20°C with calcium chloride (75 g / 100 mL), followed by calcium lactate (8 g / 100 mL) and calcium gluconate (3 g / 100 mL), so it is desirable to add an appropriate amount relative to the acid value for optimal crosslinking.

[0085] According to one embodiment of the present invention, the content of the metallic crosslinking agent may be 25 mol% or more and 75 mol% or less with respect to the carboxyl group-modified polyvinyl alcohol solution. Specifically, the content of the metallic crosslinking agent may be 30 mol% or more and 70 mol% or less, 35 mol% or more and 65 mol% or less, 40 mol% or more and 60 mol% or less, 45 mol% or more and 55 mol% or less, and 47 mol% or more and 53 mol% or less with respect to the carboxyl group-modified polyvinyl alcohol solution. By controlling the content of the metallic crosslinking agent within the above-described range, the carboxyl group-modified polyvinyl alcohol is crosslinked to maintain the oxygen barrier effect of general polyvinyl alcohol while simultaneously improving moisture barrier properties, and an eco-friendly manufacturing process can be realized during the coating process.

[0087] According to one embodiment of the present invention, the coating composition may further include an antifoaming agent. By further including the antifoaming agent, the degassing effect of the carboxyl group-modified polyvinyl alcohol can be improved.

[0088] According to one embodiment of the present invention, the defoaming agent may be a fatty acid-based defoaming agent comprising a fatty acid having 1 to 30 carbon atoms, a silicone-based defoaming agent, or an alcohol-based defoaming agent comprising an alkyl group having 1 to 10 carbon atoms. Specifically, the fatty acid-based defoamer may include one or more of decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, mineral oil, and oxystearin, the silicone-based defoamer may include one or more of dimethyl polysiloxane, silicon dioxide, sorbitan monostearate, and silicon resin, and the alcohol-based defoamer containing an alkyl group may include one or more of pentyl alcohol, hexyl alcohol, octyl alcohol, isobutyl alcohol, isooctyl alcohol, butyl alcohol, and sec-butyl alcohol. By selecting the type of defoaming agent from the above, the defoaming effect of carboxyl group-modified polyvinyl alcohol can be improved.

[0089] According to one embodiment of the present invention, the defoaming agent may further comprise a polysaccharide. Specifically, the polysaccharide may be selected from the group consisting of chitosan, cellulose nanocrystals, cellulose nanofibers, modified cellulose, chitin, and combinations thereof. More specifically, the polysaccharide additive is preferably chitosan, cellulose nanofibers, chitin, etc. Although chitosan has low solubility in water, it can improve water solubility and enhance antibacterial effects as its amino groups are cationized into ammonia groups in dilute acids. Cellulose nanofibers are flexible and have a high aspect ratio, which can enhance the gas barrier effect. Chitin can block gas more effectively by making the bonding between particles denser.

[0090] According to one embodiment of the present invention, the content of the defoaming agent may be 0.1 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the carboxyl group-modified polyvinyl alcohol solution. Specifically, the content of the defoaming agent may be 0.2 parts by weight or more and 4 parts by weight or less, 0.4 parts by weight or more and 3 parts by weight or less, 0.6 parts by weight or more and 2 parts by weight or less, 0.8 parts by weight or more and 1.5 parts by weight or less, and 0.9 parts by weight or more and 1.2 parts by weight or less, per 100 parts by weight of the carboxyl group-modified polyvinyl alcohol solution. By adjusting the content of the defoaming agent within the above-described range, the degassing effect of the carboxyl group-modified polyvinyl alcohol can be improved.

[0092] The above conductive filler may be used without limitation as long as it has conductivity. Specifically, the above conductive filler may include one or more of carbon black, graphite, silver, copper, nickel, and aluminum.

[0093] The particle shape of the above conductive filler can be sphere, flake, dendrite, core-shell type, etc.

[0094] The content of the conductive filler may be 1 part by weight or more and 99 parts by weight or less per 100 parts by weight of the coating liquid containing the coating composition. Preferably, it may be 10 parts by weight or more and 80 parts by weight or less, and more preferably, 20 parts by weight or more and 60 parts by weight or less.

[0096] According to one embodiment of the present invention, as a means for transferring heat during the process of preparing the modified polyvinyl alcohol solution having the carboxyl group, a direct heat transfer method to a reaction vessel including a heating mantle, a heating plate, etc. may be applied. Specifically, it is preferable to use a constant temperature circulator using a double-jacketed reaction vessel. By selecting the means for transferring heat from the above, heat can be transferred uniformly.

[0098] According to one embodiment of the present invention, the coating composition may further comprise an inorganic pigment or an organic pigment. Specifically, the shape of the inorganic pigment and / or the organic pigment may be a hollow form or a core-shell form. Furthermore, the organic pigment and / or the inorganic pigment may be included alone or in a mixture of two or more types. As described above, by the coating composition further comprising an inorganic pigment or an organic pigment, the protective properties of the adhesive layer can be improved.

[0100] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0102] A conductive tape comprising a coating layer containing carboxyl group-modified polyvinyl alcohol on one surface of a release film layer.

[0103] Example 1

[0104] A reflux condenser, a stirrer, a thermometer, and an inlet were prepared in a 4-neck double-jacketed reaction vessel connected to a constant temperature circulator. Then, 1,800 g of water and 200 g of OCA P-17 polyvinyl alcohol were added, and a polyvinyl alcohol solution was prepared by stirring sufficiently under conditions of a constant temperature of 90 ℃ and stirring at 400 rpm. 40.873 g of oxalic acid as a polycarboxylic acid derivative was added to 2,000 g of the polyvinyl alcohol solution cooled to room temperature and stirred to dissolve it. Afterward, the temperature of the constant temperature circulator was raised to 100 ℃ and the reaction was carried out for 24 hours. The reacted solution was cooled to room temperature and reprecipitated by slowly adding it dropwise to 10 times the volume of an ethanol solution using a dropping funnel while stirring at 400 rpm to obtain a solid. The above-mentioned solid was washed once more with an ethanol solution and dried under vacuum for more than one day to obtain a carboxyl group-modified polyvinyl alcohol solid.

[0105] A carboxyl group-modified polyvinyl alcohol solution was prepared by dissolving the above-prepared carboxyl group-modified polyvinyl alcohol in water to a solid content of 5% by weight. Calcium hydroxide was added as a metal crosslinking agent at a concentration of 50 mol% relative to the carboxyl group-modified polyvinyl alcohol solution and mixed by stirring for 24 hours. The mixed solution was filtered under reduced pressure using a 400-mesh nylon fabric filter to remove foreign substances. To the filtered solution, 1 part by weight of sec-butyl alcohol was added as an antifoaming agent to 100 parts by weight of the carboxyl group-modified polyvinyl alcohol solution and mixed. A coating composition was then prepared by carrying out a degassing process under reduced pressure in a desiccator.

[0106] The above coating composition is 5 g / m 2A silicone coating layer was formed on one side of a release film (paper) and coated on the other side using a bar coater. The release film coated with the coating composition was dried in an internal circulation dryer at 80°C for 10 minutes. This process was repeated twice to form a two-layer coating layer. A conductive tape was manufactured by attaching the release film prepared in this way onto a conductive substrate layer containing conductive fibers and an adhesive layer formed on one side of the conductive substrate layer (the side of the release film where the coating layer was formed with the coating composition).

[0108] Example 2

[0109] A conductive tape was prepared by including a coating layer containing carboxyl group-modified polyvinyl alcohol on one side of a release film layer in the same manner as in Example 1, except that a metal foil was used instead of a conductive fiber as the conductive substrate layer.

[0111] Example 3

[0112] A conductive tape comprising a coating layer containing carboxyl group-modified polyvinyl alcohol on one surface of a release film layer was prepared in the same manner as in Example 1, except that a release film is attached to a conductive substrate layer containing conductive fibers and an adhesive layer formed on both sides of the conductive substrate layer (the side of the release film on which a coating layer is formed with the coating composition).

[0114] Example 4

[0115] A conductive tape comprising a coating layer containing carboxyl group-modified polyvinyl alcohol on one surface of a release film layer was prepared in the same manner as in Example 2, except that a release film is attached to a conductive substrate layer comprising a metal foil and an adhesive layer formed on both sides of the conductive substrate layer (the surface of the release film on which a coating layer is formed with the coating composition).

[0117] A conductive tape comprising a coating layer containing carboxyl group-modified polyvinyl alcohol on one surface of a conductive substrate layer

[0118] Example 5

[0119] A reflux condenser, a stirrer, a thermometer, and an inlet were prepared in a 4-port double-jacketed reaction vessel connected to a thermostatic circulator. Then, 1,800 g of water and 200 g of OCA P-17 polyvinyl alcohol were added, and a polyvinyl alcohol solution was prepared by stirring thoroughly under conditions of a constant temperature of 90 ℃ and stirring at 400 rpm. After cooling the polyvinyl alcohol solution to room temperature, 40.873 g of oxalic acid as a polycarboxylic acid derivative was added to 2,000 g of the solution and dissolved by stirring. Subsequently, the temperature of the thermostatic circulator was raised to 100 ℃ and the reaction was carried out for 24 hours. The reacted solution was cooled to room temperature and reprecipitated by slowly adding it dropwise to 10 times the volume of an ethanol solution using a dropping funnel while stirring at 400 rpm to obtain a solid. The above-mentioned solid was washed once more with an ethanol solution and dried under vacuum for more than one day to obtain a carboxylic acid-modified polyvinyl alcohol solid.

[0120] A carboxylic acid-modified polyvinyl alcohol solution was prepared by dissolving the above-prepared carboxylic acid-modified polyvinyl alcohol solid content in water to a concentration of 5% by weight. Calcium hydroxide was added as a metal crosslinking agent at a concentration of 50 mol% relative to the carboxylic acid in the carboxylic acid-modified polyvinyl alcohol solution, and the mixture was stirred and mixed for 24 hours. The mixed solution was filtered under reduced pressure using a 400-mesh nylon fabric filter to remove foreign substances. To the filtered solution, 1 part by weight of sec-butyl alcohol as an antifoaming agent and 30 parts by weight of silver (Ag) flakes as a conductive filler were added and mixed with 100 parts by weight of the carboxylic acid-modified polyvinyl alcohol solution. A coating composition was then prepared by carrying out a degassing process under reduced pressure on a desiccator.

[0121] The above coating composition is 5 g / m 2Using a bar coater, a release film layer and an adhesive layer were sequentially formed on one side, and the other side of a conductive substrate layer containing conductive fibers was coated and dried in an internal circulation dryer at 80°C for 10 minutes. This process was repeated twice to form a two-layer coating layer, thereby manufacturing a conductive tape.

[0123] Example 6

[0124] A conductive tape was manufactured in the same manner as in Example 5 above, except that a metal foil was used instead of a conductive fiber as the conductive substrate layer.

[0126] Comparative Example 1

[0127] A conductive tape was prepared in the same manner as in Example 1 above, except that polyvinyl alcohol was used instead of carboxyl group-modified polyvinyl alcohol.

[0129] Comparative Example 2

[0130] A conductive tape was prepared in the same manner as in Example 3 above, except that polyvinyl alcohol was used instead of carboxyl group-modified polyvinyl alcohol.

[0132] Comparative Example 3

[0133] A conductive tape was prepared in the same manner as in Example 5 above, except that polyvinyl alcohol was used instead of carboxyl group-modified polyvinyl alcohol.

[0135] According to the experimental examples below, the oxygen permeability, moisture permeability, adhesive strength, and electromagnetic shielding rate of the conductive tapes prepared in the above examples and comparative examples were measured.

[0137] Experimental Example 1 (Oxygen Permeability)

[0138] The oxygen transmittance rate (OTR) of the conductive tapes prepared in the above examples and comparative examples was evaluated in accordance with the international standard ASTM D-3985 using an oxygen transmittance measuring device (OX-TRAN Model 2 / 21, Mocon). Specifically, specimens of the conductive tapes prepared in the above examples and comparative examples were prepared with dimensions of 5 cm in width and length, and measurements were taken at 1-hour intervals for more than 18 hours under conditions of relative humidity 0%, temperature 23℃, oxygen purity 99.9%, and supply pressure 1 atm.

[0140] Experimental Example 2 (Moisture Permeability)

[0141] The water vapor transmission rate (WVTR) of the conductive tapes prepared in the above examples and comparative examples was evaluated according to the international standard ASTM F-1249 using a water vapor transmission rate measuring device (PERMATRAN-W Model 3 / 33, Mocon). Specifically, specimens of the conductive tapes prepared in the above examples and comparative examples were prepared with dimensions of 5 cm in width and length, and measurements were taken for more than 12 hours at 1-hour intervals under conditions of 90% relative humidity and 37.8°C temperature.

[0143] Experimental Example 3 (Adhesion)

[0144] Measurements were taken using a UTM (Instron 5966) device with the conductive tapes prepared in the above examples and comparative examples, and the specimen size was fabricated to be 2.54 * 15 cm. When attaching the fabricated specimen to a SUS substrate, it was processed twice up and down using a 2 kg manual roller, and 180 o The adhesive strength was measured by performing a peel test at the peel angle.

[0146] Experimental Example 4 (Electromagnetic shielding rate)

[0147] Using the conductive tapes prepared in the above examples and comparative examples, specimens were prepared in accordance with the international standard ASTM-D4935 and evaluated. The specimens were prepared with a thickness of 0.02 mm, and the frequency range was measured from 1.5 GHz to 8 GHz.

[0149] The above measurement results are shown in Table 1 below.

[0150] item Oxygen permeability (cc / m²) 2 day) Moisture permeability (g / m²) 2 day) Adhesion (gf / inch) Electromagnetic shielding rate (dB) Example 1 1.7 6.1 1174 62 Example 2 0.15 0.10 1187 60 Example 3 1.1 2.7 1194 63 Example 4 0.11 0.06 1159 61 Example 5 2.0 8.5 1176 60 Example 6 0.22 0.14 1152 60 Comparative Example 1 fail fail 773 41 Comparative Example 2 fail 3,827.6 626 35 Comparative Example 3 fail fail 631 38

[0151] As shown in Table 1 above, Examples 1 to 6 include a coating layer containing the carboxyl group-modified polyvinyl alcohol, thereby the oxygen permeability of the conductive tape is 2.0 cc / m 2 less than day, moisture permeability 8.5 g / m² 2 It shows an excellent oxygen and moisture blocking effect for less than one day, and accordingly, it can be confirmed that the adhesive strength and electromagnetic shielding efficiency are not reduced, with an adhesive strength of 1100 gf / inch or more and an electromagnetic shielding rate of 60 dB or more.

[0152] In contrast, for Comparative Examples 1 to 3, which do not contain the above-mentioned carboxyl group-modified polyvinyl alcohol, oxygen permeability cannot be measured at all, and regarding moisture permeability, only Comparative Example 2 is measurable, with a value of as much as 3,827.6 g / m² 2 It can be confirmed that the values ​​are so high that they cannot even be compared with the values ​​of the examples. In other words, when the coating composition does not include carboxyl group-modified polyvinyl alcohol, there is a problem in that oxygen and moisture blocking is not properly achieved, and as a result, the adhesive strength of the comparative examples is about 700 gf / inch or less and the electromagnetic shielding rate is about 40 dB or less, so it can be confirmed that the adhesive strength and electromagnetic shielding efficiency are reduced.

[0154] Although the present invention has been described above by limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

Claims

Claim 1 A conductive tape for electromagnetic shielding comprising: a conductive substrate layer; an adhesive layer located on at least one surface of the conductive substrate layer; and a release film layer located on the adhesive layer, wherein the conductive tape is formed from a coating composition comprising a carboxyl group-modified polyvinyl alcohol solution, a metallic crosslinking agent, and an antifoaming agent, and further comprises a coating layer located on at least one of the conductive substrate layer and at least one surface of the release film layer, wherein the metallic crosslinking agent is an inorganic calcium salt or an organic calcium salt. Claim 2 A conductive tape for electromagnetic shielding according to claim 1, wherein when the coating layer is located on one surface of the release film layer, the other surface of the release film layer further comprises a silicone coating layer. Claim 3 A conductive tape for electromagnetic shielding according to claim 1, wherein when the coating layer is located on at least one surface of the conductive substrate layer, the coating layer further comprises a conductive filler. Claim 4 A conductive tape for electromagnetic shielding according to claim 1, wherein the carboxyl group modified polyvinyl alcohol is formed from the reaction of one or more of a polycarboxylic acid derivative, a carboxylic acid anhydride, an aldehyde derivative containing a carboxyl group, and an acrylic acid derivative containing a carboxyl group with a polyvinyl alcohol aqueous solution containing polyvinyl alcohol. Claim 5 delete Claim 6 A conductive tape for electromagnetic shielding according to claim 1, wherein the defoaming agent is a fatty acid-based defoaming agent comprising a fatty acid having 1 to 30 carbon atoms, a silicone-based defoaming agent, or an alcohol-based defoaming agent comprising an alkyl group having 1 to 10 carbon atoms. Claim 7 A conductive tape for electromagnetic shielding according to claim 1, wherein the conductive substrate comprises one or more selected from conductive fibers, metal foils, and conductive nonwoven fabrics. Claim 8 A conductive tape for electromagnetic shielding according to claim 1, wherein the carboxyl group modified polyvinyl alcohol solution contains a carboxyl group modified polyvinyl alcohol solid content of 2% by weight or more and 8% by weight or less. Claim 9 A conductive tape for electromagnetic shielding according to claim 1, wherein the metallic crosslinking agent is included in an amount of 25 mol% or more and 75 mol% or less with respect to the carboxyl group-modified polyvinyl alcohol solution. Claim 10 A conductive tape for electromagnetic shielding according to claim 1, wherein the defoaming agent is included in an amount of 0.1 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the carboxyl group modified polyvinyl alcohol solution.

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