WO2008150117A2 - Manufacturing method of emi shielding fabric sheet with hot-melt adhesive layer - Google Patents

Manufacturing method of emi shielding fabric sheet with hot-melt adhesive layer Download PDF

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Publication number
WO2008150117A2
WO2008150117A2 PCT/KR2008/003160 KR2008003160W WO2008150117A2 WO 2008150117 A2 WO2008150117 A2 WO 2008150117A2 KR 2008003160 W KR2008003160 W KR 2008003160W WO 2008150117 A2 WO2008150117 A2 WO 2008150117A2
Authority
WO
WIPO (PCT)
Prior art keywords
hot
conductive fabric
melt
fabric member
resin
Prior art date
Application number
PCT/KR2008/003160
Other languages
French (fr)
Other versions
WO2008150117A3 (en
Inventor
Kyeong-Keun Oh
Chang-Hoon Lee
Jae-Seok Lim
Hyun-Jae Cho
Seung-Hwan Moon
Ho-Sung Kang
Original Assignee
Advanced Materials & Integration Co., Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020070055017A external-priority patent/KR100839130B1/en
Priority claimed from KR1020070055018A external-priority patent/KR100882483B1/en
Application filed by Advanced Materials & Integration Co., Ltd filed Critical Advanced Materials & Integration Co., Ltd
Publication of WO2008150117A2 publication Critical patent/WO2008150117A2/en
Publication of WO2008150117A3 publication Critical patent/WO2008150117A3/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
    • B32B37/1284—Application of adhesive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0007—Casings
    • H05K9/0015—Gaskets or seals
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/009—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive fibres, e.g. metal fibres, carbon fibres, metallised textile fibres, electro-conductive mesh, woven, non-woven mat, fleece, cross-linked
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2305/00—Condition, form or state of the layers or laminate
    • B32B2305/10—Fibres of continuous length
    • B32B2305/18—Fabrics, textiles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric

Definitions

  • the present invention relates to a method for manufacturing a conductive fabric sheet comprising a hot-melt layer, in which the conductive fabric sheet is used in a gasket for shielding electromagnetic waves. More particularly, the present invention relates to an improved method for manufacturing a conductive fabric sheet comprising a hot-melt layer formed on a conductive fabric member, in which the conductive fabric sheet is manufactured using a process comprising preparing a thin flat hot-melt film and laminating the prepared hot-melt film onto a conductive fabric member through an adhesive, instead of using a process of applying hot-melt resin directly to a conductive fabric member.
  • the method of the present invention can significantly reduce the consumption of hot-melt resin compared to the prior method, can prevent the electrical conductivity of the conductive fabric member from being reduced due to the infiltration of hot-melt resin between the textures of the conductive fabric member and can increase the bonding strength between the hot-melt layer and the conductive fabric member.
  • various devices generating electromagnetic waves are provided with suitable shielding members, such that electromagnetic waves generated in the devices can be shielded from being emitted to the outside of the devices.
  • conductive gaskets are widely used as shielding members for shielding unnecessary electromagnetic waves, which leak to the outside of devices through the gaps (e.g., interfaces or joints of cases.
  • FIG. 1 shows an example of the above-described conductive gasket for shielding electromagnetic waves.
  • the conductive gasket generally comprises a long band-shaped elastic core 2 and a conductive fabric member 3 for shielding electromagnetic waves, which is covered around the elastic core 2.
  • the elastic core 2 is manufactured in various shapes (e.g., a semicircular shape as shown in FIG. 1, or a rectangular cross-sectional, circular cross-sectional or flat shape) depending on the location where the gasket 1 is placed.
  • the conductive fabric member 3 is obtained by coating a metal component on a non-conductive fabric member such as polyester to render the fabric conductive member and adheres to the elastic core 2 so as to cover around the elastic core 2, such that it functions to provide electromagnetic wave shielding performance to the gasket.
  • the gasket 1 may, if necessary, comprise a double sided adhesive tape 4 on the outside thereof, such that it can adhere to electronic products or the like.
  • an adhesion method employing a hot-melt adhesive is mainly used to attach the conductive fabric member around the elastic core 2.
  • the hot-melt adhesive is a kind of adhesive, which is made of polymer resin as a main material and, when heated for use, melts to become viscous, thus showing adhesive properties.
  • such a hot-melt adhesive is coated on one side of the conductive fabric member to fabricate a conductive fabric sheet having a hot- melt adhesive layer, the hot-melt layer of the conductive fabric sheet is heated in a state in which it is placed on the outer surface of the elastic core, such that the conductive fabric member can adhere (hot-melt bond) integrally to the elastic core by the hot-melt adhesive.
  • the method generally utilizes a process comprising applying liquid hot-melt resin directly to a conductive fabric member to a given thickness, and then aging and curing the applied hot-melt resin so as to form a hot-melt layer on the conductive fabric member.
  • US Patent No. 6,248,393 discloses a method of making a flame-retardant EMI shielding material, the method comprising applying liquid hot-melt resin to a conductive fabric member under hydrodynamic pressure and cutting the upper side of the applied liquid hot-melt resin, thus manufacturing a conductive, EMI- shielding material in which the hot-melt resin is coated on the fabric member to a given thickness. This method will be described in detail with reference to FIG. 2. As shown in FIG.
  • a coating container T containing hot-melt resin H is disposed above a conductive fabric member F, which is conveyed by a rotating supply roller, in which the coating container T is opened at the lower side coming in contact with the fabric member F, such that, as the fabric member passes through the coating container, the hot-melt resin H contained in the coating solution is coated on the surface of the fabric member under hydrodynamic pressure.
  • a gap g having a given thickness is provided between one sidewall of the container and the conductive fabric member, such that the hot-melt resin H, which is applied on the surface of the conductive fabric member, can have a given thickness corresponding to the height of the gap.
  • liquid hot-melt resin is applied directly on the surface of the fabric member. If the liquid hot-melt resin is applied directly to the conductive fabric member as described above, there is a problem in that the liquid hot-melt resin infiltrates between the textures of the fabric member to increase the consumption of the hot-melt resin, leading to an increase in material cost.
  • the above-described prior hot-melt coating process has problems in that, due to the non-conductive hot-melt resin infiltrated into the textures of the conductive fabric member, the electrical conductivity of the conductive fabric member is reduced to adversely affect the electromagnetic wave shielding performance thereof and, in addition, the conductive fabric member becomes stiff.
  • flame-retardant hot- melt resin containing a flame-retardant agent is used to ensure the flame retardant properties of a conductive gasket, the above-described problems become more serious.
  • the present inventors have conducted continued studies to develop a hot-melt coating method capable of solving the above-described problems occurring in the prior methods of coating hot-melt resin on a conductive fabric member and, as a result, have developed a novel method for manufacturing an electromagnetic wave-shielding conductive fabric sheet comprising a hot-melt layer formed coated on a conductive fabric member, in which the hot-melt layer is formed on the conductive fabric member using a novel process comprising preparing a thin flat hot-melt film and laminating the hot-melt film onto the conductive fabric member, instead of using a process of applying hot-melt resin directly to a conductive fabric member, thereby completing the present invention.
  • an object of the present invention to provide an improved method of manufacturing an electromagnetic wave-shielding fabric sheet comprising a hot- melt layer formed on a conductive fabric member, in which the method can significantly reduce the consumption of hot-melt resin compared to the prior method, can prevent the electrical conductivity of the conductive fabric member from being reduced due to the infiltration of hot-melt resin between the textures of the conductive fabric member, can increase the adhesion between the hot-melt layer and the conductive fabric member and can reduce the occurrence of burrs when the sheet is cut.
  • the present invention provides a method for manufacturing an electromagnetic wave- shielding conductive fabric sheet comprising a hot-melt layer formed on a conductive fabric member, the method comprising the steps of: (a) applying liquid hot-melt resin on a release liner and drying the applied hot-melt resin to prepare a thin, flat hot-melt film; and (b) laminating and bonding the hot- melt film, prepared in step (a) , onto a conductive fabric member.
  • the bonding of the hot-melt film with the conductive fabric member in step (b) is particularly preferably performed either using a thermal bonding process of pressing the conductive fabric member in a state in which the hot-melt film is heated, or using a process of applying an adhesive on one side of the hot-melt film and then bonding the hot-melt film integrally with the conductive fabric member by the adhesive.
  • the inventive method of coating a hot-melt layer on the fabric member to manufacture a conductive fabric sheet comprising the hot-melt layer comprises preparing a thin flat hot-melt film, and then bonding the prepared hot-melt film with a conductive fabric member, thus obtaining a conductive fabric sheet comprising the hot-melt layer formed on the conductive fabric member.
  • the characteristic manufacturing process of the present invention has advantages in that it can uniformly control the adhesion between the conductive fabric member and the hot-melt layer and can effectively solve the problems occurring in the prior process due to the infiltration of hot-melt resin into a conductive fabric member, that is, a problem of a reduction in the conductivity of the conductive fabric and a problem of an increase in the consumption of hot-melt resin.
  • the manufacturing method of the present invention can show more advantageous effects, if flame- retardant hot-melt resin is used. This is because the problem in the prior method is prominently shown, if flame- retardant hot-melt resin is used.
  • flame- retardant hot-melt resin is generally obtained by adding a flame-retardant filler to a general hot-melt composition, and if the flame-retardant hot-melt resin containing such flame- retardant filler infiltrates between the textures of a conductive fabric member, there are problems in that the electrical properties of the conductive fabric member are deteriorated and in that, due to the properties of the flarae- retardant filler consisting usually of a ceramic material, the fabric member becomes stiff, such that many wrinkles occurs on the surface of the fabric member in a process of manufacturing a gasket by covering an elastic core with the fabric member, and the elasticity of the fabric member is reduced, thus deteriorating the quality of the gasket product.
  • the conductive fabric sheet is manufactured through a process comprising preparing a hot- melt film and laminating the prepared hot-melt film onto a conductive fabric member, unlike the prior process of applying hot-melt resin directly to a conductive fabric member.
  • the manufacturing method of the present invention can significantly reduce the consumption of hot- melt resin compared to the prior process, can prevent the conductivity and flexibility of the fabric member from being reduced due to the infiltration of hot-melt resin between the textures of the conductive fabric member, can increase the bonding strength between the hot-melt layer and the conductive fabric member, and can reduce the occurrence of burrs when the fabric sheet is cut.
  • FIG. 1 shows the general structure of a conductive gasket for shielding electromagnetic waves.
  • FIG. 2 shows a knife-over-roll process which was used in the prior art to coat a conductive fabric member with hot- melt resin.
  • FIG. 3 shows a process of preparing a hot-melt film by coating a release liner with hot-melt resin in the manufacturing method of the present invention.
  • FIG. 4 shows examples of a process of laminating a hot- melt film with a conductive fabric member in the manufacturing method of the present invention.
  • FIG. 5 illustrates cross-sectional views showing hot- melt resin coated on a conductive fabric member.
  • FIG. 5 (a) is a cross-sectional view showing hot-melt resin coated according to a prior process
  • FIGS. 5(b) and 5(c) are cross-sectional views showing hot-melt resin coated according to the method of the present invention.
  • the first step of the inventive method for manufacturing a conductive fabric sheet comprising a hot-melt layer is a step of preparing a hot-melt film by processing hot-melt resin into a thin flat member.
  • a hot-melt layer is formed on a fabric member using a process comprising processing hot-melt resin into a film shape to prepare a flat hot-melt film and bonding the prepared hot-melt film with a conductive fabric member, instead of using the prior process of applying hot-melt resin directly to a conductive fabric member to coat the conductive fabric member with the hot-melt material.
  • the present invention has important technical characteristics distinguishable from the prior method for manufacturing a conductive fabric sheet comprising a hot-melt layer.
  • the hot-melt film is obtained by processing hot-melt resin into a film shape having a given thickness.
  • This hot-melt film can be prepared through a process comprising applying hot-melt resin to a release liner to a given thickness and drying and curing the applied hot-melt resin.
  • the release liner functions as a temporary release member, which is separated and removed later from the hot-melt layer, and it is generally made of a polyethylene- based synthetic resin film or coated paper.
  • the hot-melt resin that is used to prepare the hot-melt film as described above corresponds to hot-melt resin which is conventionally used as an adhesive in electromagnetic wave-shielding conductive fabric sheets comprising a hot-melt layer, and it contains, as main components, three components, a base polymer, tackifying resin and wax, and if necessary, contains an antioxidant, a plasticizer, a flame-retardant agent and the like.
  • a base polymer of the hot-melt resin an ethylene vinyl chloride copolymer (EVA) is most generally used, and polyurethane, polyamide, polyester or atactic polypropylene is also mainly used.
  • EVA ethylene vinyl chloride copolymer
  • polyurethane, polyamide, polyester or atactic polypropylene is also mainly used.
  • rosin-based resin or petroleum resin is added as a tackifier.
  • wax, an antioxidant, a flame-retardant agent, an inorganic filler, a plasticizer, etc. are added thereto .
  • the present invention can preferably be applied in the case of general hot-melt resin, it can more preferably applied in the case of flame-retardant hot-melt resin obtained by adding a flame-retardant agent to hot-melt binder resin to render the binder resin flame- retardant. This is because shortcomings such as a reduction in conductivity are more prominent, if the flame-retardant hot-melt resin is coated on a conductive fabric member according to the prior process.
  • the above-described flame-retardant hot-melt resin is obtained by dissolving polymer binder resin in a solvent and adding and dispersing a flame-retardant agent into the solution, and the composition of flame-retardant hot-melt resin used in the practice of the present invention is as follows.
  • thermoplastic polyurethane is used in an amount of 50 wt% (as solid content)
  • flame-retardant agent antimony trioxide Sb 2 ⁇ 3 and dibromodiphenyloxide (DBDPO) are used in amounts of 10-20 phr and 30-40 phr, respectively, based on 100 parts by weight of the polyurethane solids.
  • DBDPO dibromodiphenyloxide
  • flame-retardant antimony trioxide and DBDPO are added to polyurethane binder resin, dissolved in an organic solvent (MEK, toluene or DMF) , and then the flame- retardant agents were pre-mixed in the resin solution at 50- 100 rpm for about 5-10 minutes using a stirrer. Then, the composition is milled once or twice using a 3-roll mill or a ball mill in order to prevent the agglomeration of powder and to increase the kneading of each component of the composition.
  • MEK organic solvent
  • the amount of the organic solvent, which is volatilized during the dispersion process, is weighed and supplemented, and then non-dispersed flame-retardant materials and other foreign matters are removed using a #80-130-mesh sieve, thus preparing a flame-retardant hot-melt composition.
  • the hot-melt material is prepared as described above, the hot-melt material is coated on a release liner to prepare a hot-melt film.
  • a liquid hot-melt composition is applied on a release liner (or release paper) Ll, supplied from a roller Rl, to a given thickness (about 30-60 ⁇ m after drying) using a comma coater 100, and it is dried and cured by passage through a drying chamber in a dryer 200.
  • a release liner or release paper
  • the hot-melt film 20 passed through the drying chamber is laminated with a release liner L2, supplied from a second rewinder R2 and is wound into a roll shape.
  • the release liner is, if necessary, separated and removed from the one side (or both sides) of the hot-melt film 20. Then, the hot-melt film is bonded onto a conductive fabric member, thus producing a conductive fabric sheet comprising a hot-melt layer formed on the fabric member.
  • Example 1 Bonding by thermal bonding process
  • a process of laminating a conductive fabric member with a hot-melt film may comprise placing the previously prepared hot-melt film 20 and the conductive fabric member 10 on rewinders R4 and R5, respectively, passing the hot-melt film 20 and the conductive fabric member 10 between two press rollers 100a and 100b, disposed at a given interval, such that they are laid one upon another, thus bonding the hot-melt film integrally with the conductive fabric member.
  • the hot-melt film 20 is passed through the press rollers 100a and 100b in a state in which it is heated and melted, such that the lamination of the hot-melt film is achieved by thermal bonding.
  • heating means capable of heating the hot-melt resin of the hot-melt film must be provided.
  • such heating means can be provided as separate equipment, it is more preferable to provide one or more of the press rollers with heating means to construct a heating roller capable of emitting heat, such that the hot-melt film is pressed in a melted state upon passage through the press rollers and is laminated with the conductive fabric member.
  • both the two press rollers are constructed as heating rollers
  • the press roller coming in contact with the hot-melt film is constructed as a heating roller, there can be a problem in that the hot-melt resin or release liner coming in direct contact with the roller is melted.
  • the press roller coming in contact with the conductive fabric member be constructed as a heating roller, such that heat generated from the heating roller is transferred to the hot-melt film via the conductive fabric member, such that the hot-melt film can be melted and bonded onto the conductive fabric member.
  • the laminated material is aged at room temperature for a given period of time, and then the release liner is separated and removed from the hot-melt film, thus obtaining a conductive fabric sheet comprising the hot- melt layer formed on the conductive fabric member.
  • the aging process before the removal of the liner is preferably carried out at room temperature for about 4-12 hours in order to remove latent heat remaining after heating of the hot-melt resin, such that the hot-melt resin can correctly show the properties thereof.
  • the hot-melt resin can be insufficiently cured, and thus, when the release liner is removed or the laminated material is wound into a roll shape, the hot-melt layer can stick to the fabric member and can be damaged, and the adhesion between the hot-melt layer and the fabric member can be reduced.
  • Example 2 Bonding by adhesive Another preferred example of the process of laminating the conductive fabric member with the hot-melt film according to the present invention can be performed by applying an adhesive to one side of the previously prepared hot-melt film for bonding with the conductive fabric member to form an adhesive layer and laminating the hot-melt film with the conductive fabric member using the adhesive layer.
  • a two-part synthetic resin adhesive is particularly preferably used.
  • this two-part adhesive a commercial product consisting of a polyurethane base and an isocyanate curing agent is used.
  • the base and the curing agent are mixed at a ratio of 10:1.
  • the previously prepared hot-melt film 20 is placed on a rewinder R7 , and then the two-part adhesive is coated on the hot-melt film using a gravure coater 300 to a thickness of 2-10 ⁇ m (thickness after drying) at a speed of 80-100 m/min.
  • the hot-melt film 20 having the two-part adhesive 30 coated thereon is passed through a drying chamber 400 to dry the adhesive applied on the hot-melt film.
  • the adhesive is dried at a level of about 70-80% without being completely dried, such that the viscosity thereof can be maintained.
  • the hot-melt film 20 having the adhesive 30 applied thereon is laminated with a conductive fabric member 10, supplied from a second rewinder R8 , thus manufacturing a conductive fabric sheet comprising the hot-melt film 20 bonded integrally with the conductive fabric member 10 by the adhesive 10.
  • the process of laminating the hot-melt film with the conductive fabric member 10 can be performed by passing the hot-melt film through press rollers in an unheated state to bond the semi—dried adhesive to the conductive fabric member. After the conductive fabric sheet comprising the hot-melt layer is manufactured through this process, the conductive fabric sheet is aged and cured at 35-45 ° C for 36-60 hours to increase the adhesion of the hot-melt film and volatilize non-volatilized organic solvent.
  • the conductive fabric sheet comprising the hot-melt layer formed on one side of the conductive fabric member is obtained.
  • the produced conductive fabric sheet is covered around an elastic foam core, and then bonded to the core by thermal bonding, and the resulting structure can be used to manufacture, for example, conductive gaskets.
  • the prior method of manufacturing the conductive fabric sheet comprising the hot-melt layer is a process of applying a liquid hot-melt composition directly to the conductive fabric member, and thus the prior method has problems in that, due to the infiltration of hot-melt resin between the textures of the conductive fabric member, the loss of material increases and the electrical conductivity of the conductive fabric member is reduced. Specifically, as can be seen in FIG.
  • the prior process of applying liquid hot-melt resin directly to the conductive fabric member has problems in that, because the hot-melt material infiltrates between the weft and warp of the conductive fabric member and runs to the surface of the conductive fabric member, the consumption of the material increases and the properties (conductivity and flexibility) of the metallic fabric member are deteriorated.
  • the hot-melt layer is formed on the conductive fabric member using the process comprising coating and drying liquid hot-melt resin on a separate release liner to prepare a hot-melt film and bonding the prepared hot-melt film onto the conductive fabric member, instead of using the process of applying hot-melt resin directly to the conductive fabric member.
  • the present invention when the present invention is applied, the infiltration thickness of the hot-melt layer into the conductive fabric member is relatively very small.
  • the present invention can effectively the above-described problems occurring in the prior art, such as an increase in material consumption and a reduction in conductivity, and can increase the bonding strength between the hot-melt layer and the conductive fabric member compared to that in the prior method.
  • FIGS. 4 (b) and 4 (c) show the cross-sections of the conductive hot-melt sheets comprising the hot-melt layer, produced according to the manufacturing method of the present invention.
  • the conductive fabric sheet comprising the hot-melt layer, manufactured according to Example 1 of the present invention can effectively solve the above-described problems occurring in the prior art, such as an increase in material consumption and a reduction in conductivity, because the hot-melt resin 20 is bonded to only the surface of the conductive fabric member 10 without passing through the textures of the conductive fabric member.
  • the two-part adhesive 30 applied to the lower surface of the conductive fabric member 10 slightly infiltrates only the surface of the conductive fabric member 10, and the hot-melt film 20 is bonded to the lower surface of the adhesive 30.
  • the hot-melt resin does not infiltrate between the textures of the conductive fabric member, unlike the prior process.
  • the weft 11 and warp 12 of the conductive fabric member 10 are firmly bonded to each other due to the high adhesive force of the adhesive 30, thus making it possible to prevent burrs from occurring at the ends of the sheet when the sheet is cut.
  • the inventive conductive fabric sheet comprising the hot-melt layer the occurrence of burrs is reduced and, for this reason, when the conductive fabric sheet is applied to a conductive gasket to produce a product, the occurrence of electrical short circuits resulting from the falling out of unit fibers can be prevented.
  • the present invention provides a method of manufacturing a conductive fabric sheet comprising a hot-melt layer as an adhesive layer formed on one side of a conductive fabric member.
  • the conductive fabric sheet produced according to the present invention can be covered around an elastic foam core, and then bonded to the core by hot-melt bonding.
  • the conductive fabric member of the present invention can be used to manufacture a conductive gasket for shielding e ' lectromagnetic waves, which are emitted from various electronic devices, including mobile phone terminals, notebook computers and business machines.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Textile Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Abstract

The present invention relates to a method for manufacturing a conductive fabric sheet comprising a hot-melt layer, in which the conductive fabric sheet is used in a gasket for shielding electromagnetic waves. The present invention provides a method for manufacturing an electromagnetic wave-shielding conductive fabric sheet comprising a hot-melt layer formed on a conductive fabric member, the method comprising the steps of : (a) applying liquid hot-melt resin on a release liner and drying the applied hot-melt resin to prepare a thin, flat hot-melt film; and (b) laminating and bonding the hot-melt film, prepared in step (a), onto a conductive fabric member. The manufacturing method of the present invention can significantly reduce the consumption of hot-melt resin compared to the prior process, can prevent the conductivity and flexibility of the fabric member from being reduced due to the infiltration of hot-melt resin between the textures of the conductive fabric member, can increase the bonding strength between the hot-melt layer and the conductive fabric member, and can reduce the occurrence of burrs when the fabric sheet is cut.

Description

[DESCRIPTION]
[invention Title]
MANUFACTURING METHOD OF EMI SHIELDING FABRIC SHEET WITH HOT-MELT ADHESIVE LAYER [Technical Field]
The present invention relates to a method for manufacturing a conductive fabric sheet comprising a hot-melt layer, in which the conductive fabric sheet is used in a gasket for shielding electromagnetic waves. More particularly, the present invention relates to an improved method for manufacturing a conductive fabric sheet comprising a hot-melt layer formed on a conductive fabric member, in which the conductive fabric sheet is manufactured using a process comprising preparing a thin flat hot-melt film and laminating the prepared hot-melt film onto a conductive fabric member through an adhesive, instead of using a process of applying hot-melt resin directly to a conductive fabric member. Thus, the method of the present invention can significantly reduce the consumption of hot-melt resin compared to the prior method, can prevent the electrical conductivity of the conductive fabric member from being reduced due to the infiltration of hot-melt resin between the textures of the conductive fabric member and can increase the bonding strength between the hot-melt layer and the conductive fabric member. [Background Art]
In general, all electronic devices, which use electricity, including mobile telecommunication terminals, notebook computers, office machines and the like, have a property of emitting electromagnetic waves to the surrounding region during the operation thereof. Particularly, highspeed digital devices, which have recently appeared due to the development of microelectronic technology, frequently generate broadband electromagnetic waves. Such electromagnetic waves, which are generated from the constituting elements of electronic devices, can cause the so-called electromagnetic interference that causes unnecessary interference in the surrounding devices or between the surrounding devices to cause the mis-operation of the devices. Particularly, as the integration density of devices increases in accordance with the recent trend toward highly functional, small-sized and lightweight electronic products, electromagnetic interference increasingly becomes a serious problem. In addition, there have been continued reports that such electromagnetic waves can have direct or indirect effects on various diseases, such as causing headaches, eyesight weakness, brain tumors, circulatory system disorders, a decrease in reproductive function, VDT syndromes and the like. For this reason, the discussion of the harmful effects of electromagnetic waves on the human body increases, and thus a need for electromagnetic wave shielding further increases.
Accordingly, various devices generating electromagnetic waves are provided with suitable shielding members, such that electromagnetic waves generated in the devices can be shielded from being emitted to the outside of the devices. Usually, conductive gaskets are widely used as shielding members for shielding unnecessary electromagnetic waves, which leak to the outside of devices through the gaps (e.g., interfaces or joints of cases.
FIG. 1 shows an example of the above-described conductive gasket for shielding electromagnetic waves. As shown in FIG. 1, the conductive gasket generally comprises a long band-shaped elastic core 2 and a conductive fabric member 3 for shielding electromagnetic waves, which is covered around the elastic core 2. The elastic core 2 is manufactured in various shapes (e.g., a semicircular shape as shown in FIG. 1, or a rectangular cross-sectional, circular cross-sectional or flat shape) depending on the location where the gasket 1 is placed. The conductive fabric member 3 is obtained by coating a metal component on a non-conductive fabric member such as polyester to render the fabric conductive member and adheres to the elastic core 2 so as to cover around the elastic core 2, such that it functions to provide electromagnetic wave shielding performance to the gasket. Herein, the gasket 1 may, if necessary, comprise a double sided adhesive tape 4 on the outside thereof, such that it can adhere to electronic products or the like. In the manufacture of the above-described conductive gasket, an adhesion method employing a hot-melt adhesive is mainly used to attach the conductive fabric member around the elastic core 2. As well known in the art, the hot-melt adhesive is a kind of adhesive, which is made of polymer resin as a main material and, when heated for use, melts to become viscous, thus showing adhesive properties. In the fabrication of the conductive gasket, such a hot-melt adhesive is coated on one side of the conductive fabric member to fabricate a conductive fabric sheet having a hot- melt adhesive layer, the hot-melt layer of the conductive fabric sheet is heated in a state in which it is placed on the outer surface of the elastic core, such that the conductive fabric member can adhere (hot-melt bond) integrally to the elastic core by the hot-melt adhesive. Meanwhile, with respect to a method, which is now generally used in the art to manufacture the conductive hot- melt fabric sheet for use in the conductive gasket, that is, a method of manufacturing the conductive hot-melt fabric sheet by coating a hot-melt adhesive on a conductive fabric member, the method generally utilizes a process comprising applying liquid hot-melt resin directly to a conductive fabric member to a given thickness, and then aging and curing the applied hot-melt resin so as to form a hot-melt layer on the conductive fabric member.
An example of a prior method of coating hot-melt resin on a conductive fabric member in the fabrication of the electromagnetic wave-shielding conductive fabric sheet comprising a hot-melt layer will now be explained with reference to a patent document. US Patent No. 6,248,393 discloses a method of making a flame-retardant EMI shielding material, the method comprising applying liquid hot-melt resin to a conductive fabric member under hydrodynamic pressure and cutting the upper side of the applied liquid hot-melt resin, thus manufacturing a conductive, EMI- shielding material in which the hot-melt resin is coated on the fabric member to a given thickness. This method will be described in detail with reference to FIG. 2. As shown in FIG. 2, a coating container T containing hot-melt resin H is disposed above a conductive fabric member F, which is conveyed by a rotating supply roller, in which the coating container T is opened at the lower side coming in contact with the fabric member F, such that, as the fabric member passes through the coating container, the hot-melt resin H contained in the coating solution is coated on the surface of the fabric member under hydrodynamic pressure. As shown in FIG. 2, in the coating container, a gap g having a given thickness is provided between one sidewall of the container and the conductive fabric member, such that the hot-melt resin H, which is applied on the surface of the conductive fabric member, can have a given thickness corresponding to the height of the gap. Due to the characteristics of this process, the above method is called a "knife-over-roll process". According to the above-described prior coating process, liquid hot-melt resin is applied directly on the surface of the fabric member. If the liquid hot-melt resin is applied directly to the conductive fabric member as described above, there is a problem in that the liquid hot-melt resin infiltrates between the textures of the fabric member to increase the consumption of the hot-melt resin, leading to an increase in material cost. In addition, the above-described prior hot-melt coating process has problems in that, due to the non-conductive hot-melt resin infiltrated into the textures of the conductive fabric member, the electrical conductivity of the conductive fabric member is reduced to adversely affect the electromagnetic wave shielding performance thereof and, in addition, the conductive fabric member becomes stiff. Particularly, if flame-retardant hot- melt resin containing a flame-retardant agent is used to ensure the flame retardant properties of a conductive gasket, the above-described problems become more serious.
Accordingly, the present inventors have conducted continued studies to develop a hot-melt coating method capable of solving the above-described problems occurring in the prior methods of coating hot-melt resin on a conductive fabric member and, as a result, have developed a novel method for manufacturing an electromagnetic wave-shielding conductive fabric sheet comprising a hot-melt layer formed coated on a conductive fabric member, in which the hot-melt layer is formed on the conductive fabric member using a novel process comprising preparing a thin flat hot-melt film and laminating the hot-melt film onto the conductive fabric member, instead of using a process of applying hot-melt resin directly to a conductive fabric member, thereby completing the present invention. [Disclosure]
[Technical Problem]
Therefore, it is an object of the present invention to provide an improved method of manufacturing an electromagnetic wave-shielding fabric sheet comprising a hot- melt layer formed on a conductive fabric member, in which the method can significantly reduce the consumption of hot-melt resin compared to the prior method, can prevent the electrical conductivity of the conductive fabric member from being reduced due to the infiltration of hot-melt resin between the textures of the conductive fabric member, can increase the adhesion between the hot-melt layer and the conductive fabric member and can reduce the occurrence of burrs when the sheet is cut. [Technical Solution] To achieve the above object, the present invention provides a method for manufacturing an electromagnetic wave- shielding conductive fabric sheet comprising a hot-melt layer formed on a conductive fabric member, the method comprising the steps of: (a) applying liquid hot-melt resin on a release liner and drying the applied hot-melt resin to prepare a thin, flat hot-melt film; and (b) laminating and bonding the hot- melt film, prepared in step (a) , onto a conductive fabric member.
In the manufacturing method of the present invention, the bonding of the hot-melt film with the conductive fabric member in step (b) is particularly preferably performed either using a thermal bonding process of pressing the conductive fabric member in a state in which the hot-melt film is heated, or using a process of applying an adhesive on one side of the hot-melt film and then bonding the hot-melt film integrally with the conductive fabric member by the adhesive.
Unlike the prior process of applying hot-melt resin directly to a conductive fabric member, the inventive method of coating a hot-melt layer on the fabric member to manufacture a conductive fabric sheet comprising the hot-melt layer comprises preparing a thin flat hot-melt film, and then bonding the prepared hot-melt film with a conductive fabric member, thus obtaining a conductive fabric sheet comprising the hot-melt layer formed on the conductive fabric member. Accordingly, the characteristic manufacturing process of the present invention has advantages in that it can uniformly control the adhesion between the conductive fabric member and the hot-melt layer and can effectively solve the problems occurring in the prior process due to the infiltration of hot-melt resin into a conductive fabric member, that is, a problem of a reduction in the conductivity of the conductive fabric and a problem of an increase in the consumption of hot-melt resin.
Particularly, the manufacturing method of the present invention can show more advantageous effects, if flame- retardant hot-melt resin is used. This is because the problem in the prior method is prominently shown, if flame- retardant hot-melt resin is used. Specifically, flame- retardant hot-melt resin is generally obtained by adding a flame-retardant filler to a general hot-melt composition, and if the flame-retardant hot-melt resin containing such flame- retardant filler infiltrates between the textures of a conductive fabric member, there are problems in that the electrical properties of the conductive fabric member are deteriorated and in that, due to the properties of the flarae- retardant filler consisting usually of a ceramic material, the fabric member becomes stiff, such that many wrinkles occurs on the surface of the fabric member in a process of manufacturing a gasket by covering an elastic core with the fabric member, and the elasticity of the fabric member is reduced, thus deteriorating the quality of the gasket product.
However, according to the manufacturing method of the present invention, the above-described problems occurring in the prior art can be effectively solved, because (flame- retardant) hot-melt resin does not infiltrate into the conductive fabric member (see FIG. 4) . Thus, the present invention can be particularly preferably applied to the case where flame-retardant hot-melt resin is to be used. [Advantageous Effects]
According to the above-described inventive method for manufacturing an electromagnetic wave-shielding conductive fabric sheet comprising a hot-melt layer formed on a conductive fabric member, the conductive fabric sheet is manufactured through a process comprising preparing a hot- melt film and laminating the prepared hot-melt film onto a conductive fabric member, unlike the prior process of applying hot-melt resin directly to a conductive fabric member. Thus, the manufacturing method of the present invention can significantly reduce the consumption of hot- melt resin compared to the prior process, can prevent the conductivity and flexibility of the fabric member from being reduced due to the infiltration of hot-melt resin between the textures of the conductive fabric member, can increase the bonding strength between the hot-melt layer and the conductive fabric member, and can reduce the occurrence of burrs when the fabric sheet is cut. [Description of Drawings]
FIG. 1 shows the general structure of a conductive gasket for shielding electromagnetic waves. FIG. 2 shows a knife-over-roll process which was used in the prior art to coat a conductive fabric member with hot- melt resin.
FIG. 3 shows a process of preparing a hot-melt film by coating a release liner with hot-melt resin in the manufacturing method of the present invention.
FIG. 4 shows examples of a process of laminating a hot- melt film with a conductive fabric member in the manufacturing method of the present invention.
FIG. 5 illustrates cross-sectional views showing hot- melt resin coated on a conductive fabric member. Specifically, FIG. 5 (a) is a cross-sectional view showing hot-melt resin coated according to a prior process, and FIGS. 5(b) and 5(c) are cross-sectional views showing hot-melt resin coated according to the method of the present invention. [Mode for Invention]
Hereinafter, the present invention will be described in further detail with reference to the accompanying drawings.
The first step of the inventive method for manufacturing a conductive fabric sheet comprising a hot-melt layer is a step of preparing a hot-melt film by processing hot-melt resin into a thin flat member. Specifically, according to the manufacturing method of the present invention, a hot-melt layer is formed on a fabric member using a process comprising processing hot-melt resin into a film shape to prepare a flat hot-melt film and bonding the prepared hot-melt film with a conductive fabric member, instead of using the prior process of applying hot-melt resin directly to a conductive fabric member to coat the conductive fabric member with the hot-melt material. In this respect, the present invention has important technical characteristics distinguishable from the prior method for manufacturing a conductive fabric sheet comprising a hot-melt layer.
Herein, the hot-melt film is obtained by processing hot-melt resin into a film shape having a given thickness. This hot-melt film can be prepared through a process comprising applying hot-melt resin to a release liner to a given thickness and drying and curing the applied hot-melt resin. Herein, the release liner functions as a temporary release member, which is separated and removed later from the hot-melt layer, and it is generally made of a polyethylene- based synthetic resin film or coated paper. The hot-melt resin that is used to prepare the hot-melt film as described above corresponds to hot-melt resin which is conventionally used as an adhesive in electromagnetic wave-shielding conductive fabric sheets comprising a hot-melt layer, and it contains, as main components, three components, a base polymer, tackifying resin and wax, and if necessary, contains an antioxidant, a plasticizer, a flame-retardant agent and the like. As the base polymer of the hot-melt resin, an ethylene vinyl chloride copolymer (EVA) is most generally used, and polyurethane, polyamide, polyester or atactic polypropylene is also mainly used. To the base polymer, rosin-based resin or petroleum resin is added as a tackifier. Also, wax, an antioxidant, a flame-retardant agent, an inorganic filler, a plasticizer, etc. are added thereto . Meanwhile, although the present invention can preferably be applied in the case of general hot-melt resin, it can more preferably applied in the case of flame-retardant hot-melt resin obtained by adding a flame-retardant agent to hot-melt binder resin to render the binder resin flame- retardant. This is because shortcomings such as a reduction in conductivity are more prominent, if the flame-retardant hot-melt resin is coated on a conductive fabric member according to the prior process.
The above-described flame-retardant hot-melt resin is obtained by dissolving polymer binder resin in a solvent and adding and dispersing a flame-retardant agent into the solution, and the composition of flame-retardant hot-melt resin used in the practice of the present invention is as follows. As the polymer binder, thermoplastic polyurethane is used in an amount of 50 wt% (as solid content), and as the flame-retardant agent, antimony trioxide Sb2θ3 and dibromodiphenyloxide (DBDPO) are used in amounts of 10-20 phr and 30-40 phr, respectively, based on 100 parts by weight of the polyurethane solids.
In the process of preparing the flame-retardant hot- melt composition, flame-retardant antimony trioxide and DBDPO are added to polyurethane binder resin, dissolved in an organic solvent (MEK, toluene or DMF) , and then the flame- retardant agents were pre-mixed in the resin solution at 50- 100 rpm for about 5-10 minutes using a stirrer. Then, the composition is milled once or twice using a 3-roll mill or a ball mill in order to prevent the agglomeration of powder and to increase the kneading of each component of the composition. The amount of the organic solvent, which is volatilized during the dispersion process, is weighed and supplemented, and then non-dispersed flame-retardant materials and other foreign matters are removed using a #80-130-mesh sieve, thus preparing a flame-retardant hot-melt composition.
When the (flame-retardant ) hot-melt material is prepared as described above, the hot-melt material is coated on a release liner to prepare a hot-melt film.
Hereinafter, the manufacturing method of the present invention will be described with reference to the use of flame-retardant hot-melt resin. It is to be understood, however, that the manufacturing method of the present invention can be applied without difficulty not only to flame-retardant hot-melt resin, but also to other kinds of hot-melt materials, including general hot-melt materials. Specifically, as shown in FIG. 3, a liquid hot-melt composition is applied on a release liner (or release paper) Ll, supplied from a roller Rl, to a given thickness (about 30-60 μm after drying) using a comma coater 100, and it is dried and cured by passage through a drying chamber in a dryer 200. In the drying conditions, zone Nos. 1 and 2 are maintained at 50 °C , zone No. 3 at 80 °C , zone No. 4 at 100 °C , and zone Nos. 5, 6 and 7 at 120 °C , and the movement speed is maintained at 8-15 m/min, such that the hot-melt composition can be completely dried after it is passed through the drying chamber. The hot-melt film 20 passed through the drying chamber is laminated with a release liner L2, supplied from a second rewinder R2 and is wound into a roll shape.
After the hot-melt film 20 is prepared as described above, the release liner is, if necessary, separated and removed from the one side (or both sides) of the hot-melt film 20. Then, the hot-melt film is bonded onto a conductive fabric member, thus producing a conductive fabric sheet comprising a hot-melt layer formed on the fabric member.
Although the bonding of the hot-melt film onto the conductive fabric member can be performed using various methods, the present invention illustrates the following two methods as preferred examples of such bonding methods. Example 1: Bonding by thermal bonding process
As shown in FIG. 4 (a) , a process of laminating a conductive fabric member with a hot-melt film may comprise placing the previously prepared hot-melt film 20 and the conductive fabric member 10 on rewinders R4 and R5, respectively, passing the hot-melt film 20 and the conductive fabric member 10 between two press rollers 100a and 100b, disposed at a given interval, such that they are laid one upon another, thus bonding the hot-melt film integrally with the conductive fabric member.
In the process of laminating the hot-melt film 20 with the conductive fabric member 10, the hot-melt film 20 is passed through the press rollers 100a and 100b in a state in which it is heated and melted, such that the lamination of the hot-melt film is achieved by thermal bonding. For this purpose, heating means capable of heating the hot-melt resin of the hot-melt film must be provided. Although such heating means can be provided as separate equipment, it is more preferable to provide one or more of the press rollers with heating means to construct a heating roller capable of emitting heat, such that the hot-melt film is pressed in a melted state upon passage through the press rollers and is laminated with the conductive fabric member.
In the specific construction of such press rollers, although it can also be considered that both the two press rollers are constructed as heating rollers, it is preferable that, among the two press rollers, only the press roller coming in contact with the conductive fabric member be constructed as a heating roller, and the other press roller (coming in contact with the hot-melt film) be constructed as a general roller made of rubber material. Specifically, when the press roller coming in contact with the hot-melt film is constructed as a heating roller, there can be a problem in that the hot-melt resin or release liner coming in direct contact with the roller is melted. For this reason, it is more preferable that only the press roller coming in contact with the conductive fabric member be constructed as a heating roller, such that heat generated from the heating roller is transferred to the hot-melt film via the conductive fabric member, such that the hot-melt film can be melted and bonded onto the conductive fabric member. After the hot-melt film is laminated onto the conductive fabric member, the laminated material is aged at room temperature for a given period of time, and then the release liner is separated and removed from the hot-melt film, thus obtaining a conductive fabric sheet comprising the hot- melt layer formed on the conductive fabric member. Herein, the aging process before the removal of the liner is preferably carried out at room temperature for about 4-12 hours in order to remove latent heat remaining after heating of the hot-melt resin, such that the hot-melt resin can correctly show the properties thereof. If the release liner is removed within a short time after lamination of the conductive fabric member with the hot-melt film, the hot-melt resin can be insufficiently cured, and thus, when the release liner is removed or the laminated material is wound into a roll shape, the hot-melt layer can stick to the fabric member and can be damaged, and the adhesion between the hot-melt layer and the fabric member can be reduced. Example 2: Bonding by adhesive Another preferred example of the process of laminating the conductive fabric member with the hot-melt film according to the present invention can be performed by applying an adhesive to one side of the previously prepared hot-melt film for bonding with the conductive fabric member to form an adhesive layer and laminating the hot-melt film with the conductive fabric member using the adhesive layer.
As the adhesive for bonding the hot-melt film onto the conductive fabric member, a two-part synthetic resin adhesive is particularly preferably used. As this two-part adhesive, a commercial product consisting of a polyurethane base and an isocyanate curing agent is used. Herein, the base and the curing agent are mixed at a ratio of 10:1. Specifically, referring to FIG. 4 (b) , the previously prepared hot-melt film 20 is placed on a rewinder R7 , and then the two-part adhesive is coated on the hot-melt film using a gravure coater 300 to a thickness of 2-10 μm (thickness after drying) at a speed of 80-100 m/min. The hot-melt film 20 having the two-part adhesive 30 coated thereon is passed through a drying chamber 400 to dry the adhesive applied on the hot-melt film. Herein, the adhesive is dried at a level of about 70-80% without being completely dried, such that the viscosity thereof can be maintained. Then, the hot-melt film 20 having the adhesive 30 applied thereon is laminated with a conductive fabric member 10, supplied from a second rewinder R8 , thus manufacturing a conductive fabric sheet comprising the hot-melt film 20 bonded integrally with the conductive fabric member 10 by the adhesive 10.
The process of laminating the hot-melt film with the conductive fabric member 10 can be performed by passing the hot-melt film through press rollers in an unheated state to bond the semi—dried adhesive to the conductive fabric member. After the conductive fabric sheet comprising the hot-melt layer is manufactured through this process, the conductive fabric sheet is aged and cured at 35-45 °C for 36-60 hours to increase the adhesion of the hot-melt film and volatilize non-volatilized organic solvent.
Through the above-described lamination process, the conductive fabric sheet comprising the hot-melt layer formed on one side of the conductive fabric member is obtained. The produced conductive fabric sheet is covered around an elastic foam core, and then bonded to the core by thermal bonding, and the resulting structure can be used to manufacture, for example, conductive gaskets. In the comparison between the conductive fabric sheet, manufactured using the above-described inventive method, and the product manufactured using the prior method, the prior method of manufacturing the conductive fabric sheet comprising the hot-melt layer is a process of applying a liquid hot-melt composition directly to the conductive fabric member, and thus the prior method has problems in that, due to the infiltration of hot-melt resin between the textures of the conductive fabric member, the loss of material increases and the electrical conductivity of the conductive fabric member is reduced. Specifically, as can be seen in FIG. 4 (a) , the prior process of applying liquid hot-melt resin directly to the conductive fabric member has problems in that, because the hot-melt material infiltrates between the weft and warp of the conductive fabric member and runs to the surface of the conductive fabric member, the consumption of the material increases and the properties (conductivity and flexibility) of the metallic fabric member are deteriorated.
In comparison with the prior method, according to method of the present invention, the hot-melt layer is formed on the conductive fabric member using the process comprising coating and drying liquid hot-melt resin on a separate release liner to prepare a hot-melt film and bonding the prepared hot-melt film onto the conductive fabric member, instead of using the process of applying hot-melt resin directly to the conductive fabric member. Thus, when the present invention is applied, the infiltration thickness of the hot-melt layer into the conductive fabric member is relatively very small. Thus, the present invention can effectively the above-described problems occurring in the prior art, such as an increase in material consumption and a reduction in conductivity, and can increase the bonding strength between the hot-melt layer and the conductive fabric member compared to that in the prior method.
FIGS. 4 (b) and 4 (c) show the cross-sections of the conductive hot-melt sheets comprising the hot-melt layer, produced according to the manufacturing method of the present invention. As can be seen in FIG. 4 (b) , the conductive fabric sheet comprising the hot-melt layer, manufactured according to Example 1 of the present invention, can effectively solve the above-described problems occurring in the prior art, such as an increase in material consumption and a reduction in conductivity, because the hot-melt resin 20 is bonded to only the surface of the conductive fabric member 10 without passing through the textures of the conductive fabric member.
As shown in FIG. 4 (c) , in the case of the conductive fabric sheet comprising the hot-melt layer, manufactured according to Example 2 of the present invention, the two-part adhesive 30 applied to the lower surface of the conductive fabric member 10 slightly infiltrates only the surface of the conductive fabric member 10, and the hot-melt film 20 is bonded to the lower surface of the adhesive 30. Thus, the hot-melt resin does not infiltrate between the textures of the conductive fabric member, unlike the prior process. In addition, according to the process of bonding the hot-melt film to the conductive fabric member using an adhesive agent according to Example 2 of the present invention, the weft 11 and warp 12 of the conductive fabric member 10 are firmly bonded to each other due to the high adhesive force of the adhesive 30, thus making it possible to prevent burrs from occurring at the ends of the sheet when the sheet is cut. As described above, in the inventive conductive fabric sheet comprising the hot-melt layer, the occurrence of burrs is reduced and, for this reason, when the conductive fabric sheet is applied to a conductive gasket to produce a product, the occurrence of electrical short circuits resulting from the falling out of unit fibers can be prevented. [industrial Applicability]
As described above, the present invention provides a method of manufacturing a conductive fabric sheet comprising a hot-melt layer as an adhesive layer formed on one side of a conductive fabric member. The conductive fabric sheet produced according to the present invention can be covered around an elastic foam core, and then bonded to the core by hot-melt bonding. Thus, the conductive fabric member of the present invention can be used to manufacture a conductive gasket for shielding e'lectromagnetic waves, which are emitted from various electronic devices, including mobile phone terminals, notebook computers and business machines.

Claims

[CLAIMS]
[Claim l]
A method for manufacturing an electromagnetic-shielding conductive fabric sheet, comprising a hot-melt layer formed on a conductive fabric member, the method comprising the steps of:
(a) applying liquid hot-melt resin on a release liner and drying the applied hot-melt resin to prepare a thin flat hot-melt film; and (b) laminating and bonding the hot-melt film, prepared in step (a), onto a conductive fabric member.
[Claim 2]
The method of Claim 1, wherein the bonding of the hot- melt film with the conductive fabric member in step (b) is performed using a thermal bonding process of pressing the conductive fabric member in a state in which the hot-melt film is heated.
[Claim 3]
The method of Claim 2, wherein the step (b) is performed by passing the hot-melt film together with the conductive fabric member between two press rollers, disposed at a given interval, thus bonding the hot-melt film integrally with the conductive fabric member.
[Claim 4] The method of Claim 3, wherein at least one of the two press rollers is a heating roller provided with heating means. [Claim 5]
The method of Claim 4, wherein, among the two press rollers, the press roller coming in contact with the conductive fabric member is a heating roller provided with heating means. [Claim 6]
The method of Claim 1, the bonding of the hot-melt film onto the conductive fabric member in step (b) is performed by applying an adhesive to one side of the hot-melt film, prepared in step (a) , and then bonding the hot-melt film integrally with the conductive fabric member by the adhesive. [Claim 7]
The method of Claim 6, wherein the adhesive is a synthetic resin-based two-part adhesive. [Claim 8]
The method of Claim 1, wherein the hot-melt resin, which is used to prepare the hot-melt film in step (a) , is a flame-retardant hot-melt resin comprising a flame-retardant agent dispersed in polymer binder resin. [Claim 9]
An electromagnetic wave-shielding conductive fabric sheet comprising a hot-melt layer formed on a conductive fabric member, the conductive fabric sheet comprising: a conductive fabric member, obtained by coating a fabric member with a metal component to have electromagnetic wave shielding performance; an adhesive layer formed on one side of the conductive fabric member; and a hot-melt film, bonded to one side of the adhesive layer and obtained by processing hot-melt resin into a thin flat shape.
PCT/KR2008/003160 2007-06-05 2008-06-05 Manufacturing method of emi shielding fabric sheet with hot-melt adhesive layer WO2008150117A2 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR1020070055017A KR100839130B1 (en) 2007-06-05 2007-06-05 Manufacturing method of emi shielding fabric sheet with hot-melt adhesive layer using release liner
KR10-2007-0055017 2007-06-05
KR1020070055018A KR100882483B1 (en) 2007-06-05 2007-06-05 Manufacturing method of emi shielding fabric sheet with adhesive attached hot-melt adhesive layer
KR10-2007-0055018 2007-06-05

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