CN115538031A - Nonwoven fabric for electromagnetic wave shielding material and electromagnetic wave shielding material - Google Patents
Nonwoven fabric for electromagnetic wave shielding material and electromagnetic wave shielding material Download PDFInfo
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- CN115538031A CN115538031A CN202211194663.2A CN202211194663A CN115538031A CN 115538031 A CN115538031 A CN 115538031A CN 202211194663 A CN202211194663 A CN 202211194663A CN 115538031 A CN115538031 A CN 115538031A
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- electromagnetic wave
- wave shielding
- nonwoven fabric
- shielding material
- fiber
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- 239000000463 material Substances 0.000 title claims abstract description 225
- 239000000835 fiber Substances 0.000 claims abstract description 508
- 229920000728 polyester Polymers 0.000 claims abstract description 141
- 238000002844 melting Methods 0.000 claims abstract description 13
- 230000008018 melting Effects 0.000 claims abstract description 13
- 229910052751 metal Inorganic materials 0.000 claims description 81
- 239000002184 metal Substances 0.000 claims description 81
- 238000000576 coating method Methods 0.000 claims description 64
- 239000011248 coating agent Substances 0.000 claims description 62
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 48
- 229910052759 nickel Inorganic materials 0.000 claims description 24
- 238000007747 plating Methods 0.000 claims description 24
- 238000009713 electroplating Methods 0.000 claims description 16
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 15
- 229910052802 copper Inorganic materials 0.000 claims description 15
- 239000010949 copper Substances 0.000 claims description 15
- 238000004544 sputter deposition Methods 0.000 claims description 13
- 238000001883 metal evaporation Methods 0.000 claims 1
- 239000000758 substrate Substances 0.000 abstract description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 75
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- 238000000034 method Methods 0.000 description 47
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
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- 239000000126 substance Substances 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- LPZOCVVDSHQFST-UHFFFAOYSA-N 2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]-3-ethylpyrazol-1-yl]-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C=1C(=NN(C=1)CC(=O)N1CC2=C(CC1)NN=N2)CC LPZOCVVDSHQFST-UHFFFAOYSA-N 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
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- 238000000113 differential scanning calorimetry Methods 0.000 description 1
- 229920006240 drawn fiber Polymers 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
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- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 238000007500 overflow downdraw method Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920003207 poly(ethylene-2,6-naphthalate) Polymers 0.000 description 1
- 229920001707 polybutylene terephthalate Polymers 0.000 description 1
- 239000011112 polyethylene naphthalate Substances 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
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- 239000010959 steel Substances 0.000 description 1
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Images
Classifications
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
- D04H1/4326—Condensation or reaction polymers
- D04H1/435—Polyesters
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
- D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
- D04H1/43835—Mixed fibres, e.g. at least two chemically different fibres or fibre blends
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
- D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
- D04H1/43838—Ultrafine fibres, e.g. microfibres
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
- D04H1/542—Adhesive fibres
- D04H1/55—Polyesters
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/53—Polyethers; Polyesters
-
- 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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
- Nonwoven Fabrics (AREA)
- Paper (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Laminated Bodies (AREA)
Abstract
The present invention addresses the problem of providing a nonwoven fabric substrate for an electromagnetic wave shielding material and an electromagnetic wave shielding material that can exhibit excellent electromagnetic wave shielding properties. A nonwoven fabric for an electromagnetic wave shielding material, which is a wet nonwoven fabric comprising 2 or more types of drawn polyester staple fibers having different fiber diameters selected from among drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm, and undrawn polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less. A nonwoven fabric for an electromagnetic wave shielding material, which comprises drawn polyester staple fibers having a fiber diameter of less than 3 [ mu ] m and undrawn polyester staple fibers having a fiber diameter of 3 [ mu ] m or more and 5 [ mu ] m or less, and has a basis weight of 7g/m 2 Below, density of 0.5-0.8 g/cm 3 The wet nonwoven fabric of (1). A nonwoven fabric for an electromagnetic wave shielding material, comprising a stretched polyester staple fiber and an unstretched polyester staple fiber having a melting point of 220 ℃ or higher and 250 ℃ or lower, wherein the peel strength (longitudinal direction) of the nonwoven fabric is 2.0N/m or higher.
Description
This application is a divisional application, the application number of its parent application: 201980060627.7 (PCT/JP 2019/035633), application date: 2019.9.11, invention name: nonwoven fabric for electromagnetic wave shielding material and electromagnetic wave shielding material
Technical Field
The present invention relates to a nonwoven fabric for an electromagnetic wave shielding material and an electromagnetic wave shielding material, which are excellent in transportability of a mesh fabric and can exhibit excellent electromagnetic wave shielding properties.
Background
The electronic device generates electromagnetic waves. In addition, an electromagnetic wave shielding material is used in order to prevent electromagnetic waves from leaking to the outside of the electronic device and to prevent the electronic device from malfunctioning due to electromagnetic waves. Examples of the electromagnetic wave shielding material include a metal plate, a paint containing a metal, a metal mesh, a foamed metal, and the like. In addition, an electromagnetic wave shielding material obtained by applying a metal plating treatment to a nonwoven fabric made of polyester staple fibers is disclosed (for example, see patent documents 1 and 2).
Patent document 1 discloses an electromagnetic wave shielding material in which a continuous metal conductive layer is attached to the outer periphery of fibers and the entire periphery of the intersection of woven, knitted, or nonwoven fabrics of nonconductive fibers by a wet plating method. It is described that polyester fibers and polypropylene fibers are preferable as the chemical fibers because they are excellent in tensile strength and elongation characteristics of the base material itself and can prevent deterioration of characteristics in the step of pretreatment for plating.
Patent document 2 discloses an electromagnetic wave shielding material obtained by subjecting a wet nonwoven fabric to a metal coating treatment, which is characterized by containing polyester fibers having a single fiber fineness of 1.1dtex or less and having a thickness in the range of 10 to 30 μm.
With the recent miniaturization, higher frequency, and higher performance of electronic devices, electromagnetic wave shielding materials with thinner thickness and higher electromagnetic wave shielding properties have been required. Specifically, an electromagnetic wave shielding material having a thickness of 15 μm or less and exhibiting excellent electromagnetic wave shielding properties in a wide frequency range of 100MHz to 10GHz is required.
As in patent documents 1 and 2, when a metal coating treatment such as a metal plating treatment is applied to a nonwoven fabric, the nonwoven fabric is processed in a Roll-to-Roll (Roll) with good productivity, but there is a problem that the nonwoven fabric is wrinkled during transportation and the transportability is not excellent.
In addition, in the example of patent document 2, there is disclosed an electromagnetic wave shielding material comprising a polyester drawn fiber having a single fiber fineness of 0.1dtex and an undrawn binder fiber having a single fiber fineness of 0.2dtex, wherein the basis weight of the wet nonwoven fabric is 8g/m 2 The electromagnetic wave shielding material has a weight per unit area of 19g/m 2 The thickness was 12 μm. However, the electromagnetic wave of patent document 2 is required to be thin as an electromagnetic wave shielding materialThe shielding material has a problem that sufficient electromagnetic wave shielding properties cannot be secured. In addition, there is a problem that the metal film is peeled off.
In addition, in an electromagnetic shielding material obtained by subjecting a nonwoven fabric to a metal plating treatment, polyester staple fibers are required to be in close contact with a metal coating formed by the metal plating treatment, and therefore, it is known to subject the polyester staple fibers to an alkali treatment as a pre-plating treatment step.
Patent document 1 describes that polyester fibers can prevent deterioration of properties in a pretreatment step for plating. However, in general, the alkali treatment of the nonwoven fabric is a wet treatment, and the fibers may fall off in a water tank, which significantly reduces the workability. In addition, there is a problem that the fallen fibers adhere to the nonwoven fabric again, and thus a defect occurs in the metal plating treatment.
Documents of the prior art
Patent literature
Patent document 1: JP-A-48-40800
Patent document 2: japanese unexamined patent publication No. 2014-75485
Disclosure of Invention
Problems to be solved by the invention
The present invention has as its 1 st object the provision of a nonwoven fabric for an electromagnetic wave shielding material which is excellent in transportability and can exhibit excellent electromagnetic wave shielding properties, and an electromagnetic wave shielding material using the nonwoven fabric for an electromagnetic wave shielding material.
The present invention has a problem 2 in that it provides a nonwoven fabric for an electromagnetic wave shielding material which is thin and can exhibit excellent electromagnetic wave shielding properties, and in which a metal coating is less likely to peel off, and an electromagnetic wave shielding material using the nonwoven fabric for an electromagnetic wave shielding material.
The 3 rd object of the present invention is to provide a nonwoven fabric for an electromagnetic wave shielding material which is less likely to cause fiber separation and has high strength in an alkali treatment which is a pre-plating treatment step for an electromagnetic wave shielding material, and an electromagnetic wave shielding material using the nonwoven fabric for an electromagnetic wave shielding material.
Means for solving the problems
The present inventors have conducted intensive studies to solve the above problems, and as a result, have found the following invention.
[ claim 1] A nonwoven fabric for an electromagnetic wave shielding material, which is a wet nonwoven fabric, characterized in that the wet nonwoven fabric contains, as essential components, 2 or more types of drawn polyester staple fibers having different fiber diameters from each other, selected from among drawn polyester staple fibers having a fiber diameter of 3 [ mu ] m or more and less than 12 [ mu ] m, and undrawn polyester staple fibers having a fiber diameter of 3 [ mu ] m or more and 5 [ mu ] m or less.
<2>A nonwoven fabric for an electromagnetic wave shielding material, which is a wet nonwoven fabric, characterized by containing, as essential components, drawn polyester staple fibers having a fiber diameter of less than 3 [ mu ] m and undrawn polyester staple fibers having a fiber diameter of 3 [ mu ] m or more and 5 [ mu ] m or less, and having a basis weight of 7g/m 2 The density is 0.5 to 0.8g/cm 3 。
<3> a nonwoven fabric for electromagnetic wave shielding material, which is a wet nonwoven fabric, characterized by comprising a stretched polyester staple fiber and an unstretched polyester staple fiber having a melting point of 220 ℃ or higher and 250 ℃ or lower, and by having a peel strength (longitudinal direction) of 2.0N/m or higher.
<4> an electromagnetic wave shielding material, wherein the nonwoven fabric for electromagnetic wave shielding material of any one of <1> to <3> is subjected to a metal coating treatment.
<5> the electromagnetic wave shielding material according to <4>, wherein the metal coating treatment is 1 or more selected from the group consisting of an electroless metal plating treatment, an electroplating treatment, a metal vapor deposition treatment and a sputtering treatment.
<6> the electromagnetic wave shielding material according to <4> above, wherein the metal coating process comprises a process of forming a nickel coating by sputtering, a process of forming a copper coating by electroplating, and a process of forming a nickel coating by electroplating in this order.
<7> the electromagnetic wave shielding material according to any one of <4> to <6>, wherein the thickness of the electromagnetic wave shielding material is 15 μm or less, and the surface resistance value of the electromagnetic wave shielding material is 0.03 Ω/\9633orless.
ADVANTAGEOUS EFFECTS OF INVENTION
The present invention has the effect 1 of providing a nonwoven fabric for an electromagnetic wave shielding material which is excellent in transportability and can exhibit excellent electromagnetic wave shielding properties, and an electromagnetic wave shielding material using the nonwoven fabric for an electromagnetic wave shielding material.
The invention has the effect 2 of providing a nonwoven fabric for an electromagnetic wave shielding material which is thin and can exhibit excellent electromagnetic wave shielding properties and in which a metal coating is less likely to peel off, and an electromagnetic wave shielding material using the nonwoven fabric for an electromagnetic wave shielding material.
The invention has the effect 3 of providing a nonwoven fabric for an electromagnetic wave shielding material which is less likely to cause fiber separation during alkali treatment in a pre-plating treatment step for an electromagnetic wave shielding material and has high strength, and an electromagnetic wave shielding material using the nonwoven fabric for an electromagnetic wave shielding material.
Drawings
Fig. 1 is a schematic view showing the state of a nonwoven fabric for an electromagnetic wave shielding material when the peel strength is measured.
Detailed Description
Hereinafter, the nonwoven fabric for an electromagnetic wave shielding material and the electromagnetic wave shielding material of the present invention will be described in detail.
Nonwoven fabric for electromagnetic wave shielding material <1> -
The nonwoven fabric <1> for electromagnetic wave shielding material of the present invention is characterized by containing 2 or more types of drawn polyester staple fibers having different fiber diameters and selected from among drawn polyester staple fibers having a fiber diameter of 3 to less than 12 μm, and undrawn polyester staple fibers having a fiber diameter of 3 to 5 μm as essential components.
Generally, in the nonwoven fabric during conveyance in roll-to-roll processing, since tension is applied in the MD (Machine Direction), the nonwoven fabric stretches, and therefore wrinkles occur. Since the nonwoven fabric <1> for electromagnetic wave shielding material of the present invention contains 2 or more types of drawn polyester staple fibers having different fiber diameters and selected from among drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm, and undrawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 5 μm as essential components, the nonwoven fabric is less likely to stretch and therefore less likely to wrinkle during transportation than a nonwoven fabric containing 1 type of drawn polyester staple fibers having the same fiber diameter and selected from among drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm, and undrawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 5 μm as essential components. In addition, when a nonwoven fabric having a fiber diameter of the drawn polyester staple fibers of up to 12 μm or more is used, it is difficult to obtain a thin electromagnetic wave shielding material. The nonwoven fabric <1> for electromagnetic wave shielding material of the present invention comprises drawn polyester staple fibers having a fiber diameter of less than 12 μm and undrawn polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less, and thus can achieve the effects of being thin and excellent in transportability.
Generally, electromagnetic wave shielding is achieved by absorption and reflection loss, and multiple reflection loss of electromagnetic waves. In the nonwoven fabric <1> for an electromagnetic wave shielding material of the present invention, by using 2 or more types of drawn polyester-based short fibers having different fiber diameters selected from among drawn polyester-based short fibers having a fiber diameter of 3 μm or more and less than 12 μm, electromagnetic waves that have entered the electromagnetic wave shielding material are easily reflected repeatedly in the electromagnetic wave shielding material, and excellent electromagnetic wave shielding properties due to an improvement in multiple reflection loss can be obtained.
In the nonwoven fabric <1> for an electromagnetic wave shielding material of the present invention, the mass content ratio of the stretched polyester staple fibers to the unstretched polyester staple fibers is preferably 10: 90 to 90: 10, more preferably 20:80 to 80:20, and still more preferably 30: 70 to 70: 30. If the content of the undrawn polyester staple fibers is less than 10% by mass of the entire fibers constituting the wet nonwoven fabric, the strength required for the nonwoven fabric for an electromagnetic wave shielding material may not be exhibited. On the other hand, if the content of the undrawn polyester staple fibers exceeds 90 mass%, uniformity may be impaired.
In the nonwoven fabric <1> for an electromagnetic wave shielding material of the present invention, a drawn polyester staple fiber other than a drawn polyester staple fiber having a fiber diameter of 3 μm or more and less than 12 μm may be used. In addition, undrawn polyester staple fibers other than the undrawn polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less may be used. That is, drawn polyester staple fibers having a fiber diameter of less than 3 μm, drawn polyester staple fibers having a fiber diameter of 12 μm or more, undrawn polyester staple fibers having a fiber diameter of less than 3 μm, and undrawn polyester staple fibers having a fiber diameter of more than 5 μm can be used. These may be used alone, or 2 or more kinds of fibers having a fiber diameter may be used in combination.
In the nonwoven fabric <1> for an electromagnetic wave shielding material of the present invention, the mass content of the drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm is preferably 1 to 100 mass%, more preferably 3 to 100 mass% of all the drawn polyester staple fibers contained. When the content of the drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm is less than 1% by mass based on the total drawn polyester staple fibers, there is a case where an electromagnetic shielding material which is thin and excellent in transportability cannot be obtained.
In the nonwoven fabric <1> for electromagnetic wave shielding material of the present invention, the mass content of the undrawn polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less is preferably 1 to 100% by mass, and more preferably 2 to 100% by mass, of all the undrawn polyester staple fibers contained. When the content of the undrawn polyester-based short fibers having a fiber diameter of 3 μm or more and 5 μm or less is less than 1% by mass, the specific surface area may be small depending on the fiber diameter used in combination, and it may be difficult to exhibit excellent electromagnetic wave shielding properties. In addition, it is sometimes difficult to express the strength of the wet nonwoven fabric.
The nonwoven fabric for electromagnetic wave shielding material of the present invention is used for electronic devices<1>The thickness of (A) is preferably 7 to 30 μm, more preferably 15 μm or less. The weight per unit area (weight per unit area) is preferably 5 to 30g/m 2 More preferably 15g/m 2 The following. If the weight per unit area is less than 5g/m 2 It is difficult to obtain the effects of uniformity and electromagnetic wave shielding propertyThe deviation is easily generated.
Nonwoven fabric for electromagnetic wave shielding material <2> -
The nonwoven fabric for electromagnetic wave shielding material of the present invention<2>Characterized in that it contains, as essential components, drawn polyester staple fibers having a fiber diameter of less than 3 μm and undrawn polyester staple fibers having a fiber diameter of 3 μm to 5 μm, and has a basis weight of 7g/m 2 The density is 0.5-0.8 g/cm 3 The wet nonwoven fabric of (1).
In general, in the metal coating treatment of a wet nonwoven fabric, if the specific surface area (surface area per unit volume) of the fibers forming the wet nonwoven fabric is small, the amount of metal deposited per unit volume is small, and excellent electromagnetic wave shielding properties may not be exhibited. The nonwoven fabric <2> for an electromagnetic wave shielding material of the present invention is a wet nonwoven fabric containing, as essential components, drawn polyester-based short fibers having a fiber diameter of less than 3 μm and undrawn polyester-based short fibers having a fiber diameter of 3 μm to 5 μm, and therefore, the specific surface area can be increased and excellent electromagnetic wave shielding properties can be exhibited. In the case where the wet nonwoven fabric includes only the drawn polyester type short fibers having a fiber diameter of 3 μm or more and the undrawn polyester type short fibers having a fiber diameter exceeding 5 μm, excellent electromagnetic wave shielding properties cannot be exhibited. It is difficult to obtain undrawn polyester staple fibers having a fiber diameter of less than 3 μm. The drawn polyester staple fiber having a fiber diameter of less than 3 μm preferably has a fiber diameter of 0.1 μm or more. When the fiber diameter is less than 0.1. Mu.m, the strength may not be exhibited.
In the nonwoven fabric <2> for an electromagnetic wave shielding material of the present invention, the mass content ratio of the stretched polyester staple fibers to the unstretched polyester staple fibers is preferably 20:80 to 80:20, more preferably 30: 70 to 70: 30, and still more preferably 40: 60 to 60: 40. If the content of the undrawn polyester staple fibers is less than 20 mass% of the total fibers constituting the wet nonwoven fabric, the strength required for the nonwoven fabric for an electromagnetic wave shielding material may not be exhibited. On the other hand, if the content of the undrawn polyester staple fibers exceeds 80 mass%, uniformity may be impaired.
In the nonwoven fabric <2> for electromagnetic wave shielding material of the present invention, fibers other than the drawn polyester staple fibers having a fiber diameter of less than 3 μm and the undrawn polyester staple fibers having a fiber diameter of 3 μm to 5 μm may be used. That is, drawn polyester staple fibers having a fiber diameter of 3 μm or more, undrawn polyester staple fibers having a fiber diameter of less than 3 μm, and undrawn polyester staple fibers having a fiber diameter of more than 5 μm can be used. These may be used alone, or 2 or more kinds of fibers having a fiber diameter may be used in combination.
In the nonwoven fabric <2> for electromagnetic wave shielding material of the present invention, the content of the drawn polyester staple fibers having a fiber diameter of less than 3 μm is preferably 1 to 100% by mass, more preferably 3 to 100% by mass, based on the total of the drawn polyester staple fibers. When the content of the drawn polyester staple fibers having a fiber diameter of less than 3 μm is less than 1% by mass, the specific surface area may be small depending on the fiber diameter used in combination, and it may be difficult to exhibit excellent electromagnetic wave shielding properties.
In the nonwoven fabric <2> for electromagnetic shielding material of the present invention, the content of the undrawn polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less is preferably 1 to 100% by mass, more preferably 2 to 100% by mass, based on the total amount of the undrawn polyester staple fibers. When the content of the undrawn polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less is less than 1% by mass, the specific surface area may be small depending on the fiber diameter used in combination, and it may be difficult to exhibit excellent electromagnetic wave shielding properties, or it may be difficult to exhibit excellent strength of a wet nonwoven fabric.
The nonwoven fabric for electromagnetic wave shielding material of the present invention<2>The wet nonwoven fabric has a basis weight of 7g/m 2 Hereinafter, more preferably 5g/m 2 Hereinafter, more preferably 4g/m 2 The following. If the weight per unit area exceeds 7g/m 2 The thickness of the electromagnetic shielding material may be increased after the metal coating treatment, and the thickness of the electromagnetic shielding material may exceed 15 μm, and the electromagnetic shielding material may not be used for electronic devices, communication devices, electric appliances, and the like. In addition, wet nonwoven fabric sheetThe weight per unit area is preferably 3g/m 2 The above. The weight per unit area is determined by JIS P8124:2011 was used for the measurement.
The nonwoven fabric for electromagnetic wave shielding material of the invention<2>The wet nonwoven fabric has a density of 0.5 to 0.8g/cm 3 More preferably 0.55 to 0.65g/cm 3 . The passing density was 0.8g/cm 3 Since the specific surface area is increased, the number of metal coatings formed by the metal coating treatment increases, and the electromagnetic wave shielding property is improved. In addition, the metal coating is difficult to peel off. In addition, if the density is 0.5g/cm 3 As described above, the wet nonwoven fabric has high strength, and thus defects are less likely to occur in the metal coating treatment, and the metal coating is less likely to peel off. The density is measured by JIS P8118: 2014.
Nonwoven fabric for electromagnetic wave shielding material <3> -
The nonwoven fabric <3> for electromagnetic wave shielding material of the present invention is a wet nonwoven fabric comprising a stretched polyester staple fiber and an unstretched polyester staple fiber having a melting point of 220 ℃ to 250 ℃. The nonwoven fabric <3> for electromagnetic wave shielding material of the present invention has a peel strength (longitudinal direction) of 2.0N/m or more.
In the nonwoven fabric for electromagnetic wave shielding material <3> of the present invention, the peel strength (machine direction) of the nonwoven fabric for electromagnetic wave shielding material is 2.0N/m or more, more preferably 2.5N/m or more, and still more preferably 3.0N/m or more. When the peel strength (longitudinal direction) is less than 2.0N/m, the bonding between fibers is too weak, and therefore, the fibers are more likely to fall off from the nonwoven fabric for electromagnetic wave shielding material during the alkali treatment, and the fibers are accumulated on the transport roller, which causes problems such as deterioration in workability due to the need for regular cleaning and defects in the metal plating treatment due to the fall-off fibers being attached again to the nonwoven fabric for electromagnetic wave shielding material. In the nonwoven fabric for electromagnetic wave shielding material <3> of the present invention, the peel strength (longitudinal direction) of the nonwoven fabric for electromagnetic wave shielding material is preferably 10.0N/m or less. If the ratio exceeds 10.0N/m, the welding of the nonwoven fabric for an electromagnetic wave shielding material excessively proceeds, and the surface of the nonwoven fabric for an electromagnetic wave shielding material becomes a film, and the form cannot be maintained.
In the nonwoven fabric <3> for an electromagnetic wave shielding material of the present invention, the drawn polyester staple fibers preferably have a fiber diameter of 1 to 10 μm, more preferably 2 to 8 μm. The drawn polyester staple fibers may include 2 or more kinds of drawn polyester staple fibers having different fiber diameters. When the fiber diameter of the drawn polyester staple fibers is 10 μm or less, a thin electromagnetic wave shielding material can be easily provided. In addition, it is preferable that the drawn polyester staple fiber contains polyester staple fiber having a fiber diameter of 3 μm or less as an essential component. The electromagnetic wave shielding property is further improved by containing polyester staple fibers having a fiber diameter of 31 μm or less.
In the nonwoven fabric <3> for electromagnetic wave shielding material of the present invention, the undrawn polyester staple fibers preferably have a fiber diameter of 1 to 8 μm, more preferably 3 to 5 μm. When the fiber diameter is in this range, it is easy to provide a thin electromagnetic wave shielding material while improving the strength of the wet nonwoven fabric. The undrawn polyester staple fiber may include 2 or more types of undrawn polyester staple fibers having different fiber diameters.
In the nonwoven fabric <3> for electromagnetic wave shielding material of the present invention, the mass content ratio of the drawn polyester staple fibers to the undrawn polyester staple fibers is preferably 20: 80-80: 20. if the content of the undrawn polyester staple fibers is less than 20 mass% of the entire fibers constituting the wet nonwoven fabric, the strength required for the nonwoven fabric as an electromagnetic wave shielding material may not be exhibited. On the other hand, if the content of the undrawn polyester staple fiber exceeds 80 mass%, uniformity may be impaired. In order to improve the electromagnetic wave shielding property, the content of the drawn polyester staple fibers having a fiber diameter of 3 μm or less is more preferably 5 to 80% by mass of the entire fibers constituting the wet nonwoven fabric. In the nonwoven fabric <3> for an electromagnetic wave shielding material of the present invention, the most preferable fiber blend is 20 to 80 mass% of the undrawn polyester staple fiber, 0 to 75 mass% of the drawn polyester staple fiber having a fiber diameter of more than 3 μm and 10 μm or less, and 5 to 80 mass% of the drawn polyester staple fiber having a fiber diameter of 3 μm or less.
The nonwoven fabric for electromagnetic wave shielding material of the present invention is used for electronic devices<3>The thickness of (A) is preferably 5 to 30 μm, more preferably 20 μm or less. The weight per unit area (weight per unit area) is preferably 3 to 30g/m 2 More preferably 15g/m 2 The following. If the weight per unit area is less than 3g/m 2 It is difficult to obtain uniformity, and the effect of electromagnetic wave shielding property is likely to vary, and it is difficult to maintain the strength of the nonwoven fabric for electromagnetic wave shielding material itself, and workability is difficult.
Short fibers of polyester series
In the present invention, the drawn polyester staple fiber is a main fiber which is not easily melted or softened even by the hot rolling treatment and forms a skeleton of the wet nonwoven fabric.
In the present invention, the undrawn polyester staple fibers are melted or softened by the hot calendering treatment, and function as binder fibers for improving the strength of the wet nonwoven fabric. The melting point of the undrawn polyester-based staple fibers is preferably 220 to 250 ℃. In the nonwoven fabric <3> for an electromagnetic wave shielding material of the present invention, the melting point of the undrawn polyester staple fibers is 220 ℃ or higher and 250 ℃ or lower. When the melting point of the undrawn polyester staple fiber is lower than 220 ℃, the wet nonwoven fabric may adhere to a hot roll in the hot calendering process, and a sheet may not be formed. When the temperature exceeds 250 ℃, the fibers may not be bonded and the strength of the wet nonwoven fabric may not be exhibited. The melting point of the undrawn polyester staple fibers is more preferably 225 ℃ to 250 ℃.
The melting point of the undrawn polyester staple fiber is the peak temperature at which the temperature is raised from 25 ℃ to 300 ℃ at a temperature raising rate of 10 ℃/min in a nitrogen atmosphere by a differential scanning calorimetry apparatus.
In the examples of the present invention, the fiber diameter of the polyester staple fiber is described as the fiber diameter before the nonwoven fabric is produced. The fiber diameter of the polyester staple fiber may be measured as a diameter obtained by measuring the cross-sectional area of the polyester staple fiber by taking a magnified photograph of a 3000-fold cross-section of the wet nonwoven fabric or the electromagnetic shielding material with a microscope and calculating the cross-sectional shape of the fiber as a perfect circle, and in this case, it is preferable to obtain the arithmetic average of 10 or more fibers having substantially the same cross-sectional area.
The fiber length of the polyester staple fibers is preferably 1 to 20mm, more preferably 1 to 10mm, and still more preferably 2 to 8mm. When the fiber length of the polyester staple fiber is less than 1 mm, the strength required for wet nonwoven fabric may be difficult to be exhibited. When the fiber length of the polyester staple fiber exceeds 20mm, uniformity may be impaired.
In the present invention, examples of the polyester include polyethylene terephthalate, polyethylene isophthalate, polypropylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate and the like. Polyester-based short fibers are preferable in terms of the ability to reduce the fiber diameter for the purpose of reducing the thickness of the electromagnetic wave shield, the ease of papermaking, and the dimensional stability during alkaline treatment in the wet state during plating treatment. The polyester staple fibers may be used alone or in combination of 2 or more.
Wet non-woven fabric
The method for forming the fibers into a sheet includes various manufacturing methods such as a spunbond method, a melt-blown method, an electrospinning method, a wet method, and the like, and the nonwoven fabric for an electromagnetic shielding material of the present invention is a wet nonwoven fabric formed into a sheet by a wet method (a paper-making method), and is a nonwoven fabric having excellent strength and high uniformity. Further, as a method for bonding fibers to each other, various methods such as a chemical bonding method and a heat fusion method can be cited. Among them, the heat-sealing method is preferable in terms of excellent durability and strength and smooth surface of the nonwoven fabric.
As the thermal welding method in the wet method, a method of performing thermal welding when a sheet obtained by a papermaking method is thermally dried by a dryer used after papermaking such as a multi-cylinder dryer, a yankee dryer, or a hot air dryer may be used. Further, a method of performing thermal fusion by a thermal calendering process using a thermal calendering apparatus having a combination of rolls such as a metal heat roll/a metal heat roll, a metal heat roll/an elastic roll, and a metal heat roll/a cotton roll may be used. By the heat drying or the heat calendering treatment, the binder component is thermally melted, and thermal fusion occurs.
The conditions for hot rolling may be exemplified below, but are not limited thereto. The temperature of the heat roll in the hot calendering treatment is preferably 200 ℃ or more and 215 ℃ or less. In the case where the temperature of the heat roll is less than 200 ℃, there sometimes arises a problem that the fibers do not adhere to each other and cannot exhibit strength. On the contrary, when the temperature of the heat roll exceeds 215 ℃, the wet nonwoven fabric may stick to the heat roll, and the wet nonwoven fabric may not be a sheet. The temperature of the heat roll is more preferably 203 ℃ or higher and 210 ℃ or lower, and still more preferably 205 ℃ or higher. In the nonwoven fabric for electromagnetic wave shielding material <3> of the present invention, in order to improve the peel strength of the nonwoven fabric for electromagnetic wave shielding material, it is preferable to perform a hot calendering treatment on a wet nonwoven fabric containing a stretched polyester staple fiber and an unstretched polyester staple fiber having a melting point of 220 ℃ to 250 ℃ using a hot roll at a temperature of 200 ℃ to 215 ℃. More preferably, the temperature of the heat roll is 203 ℃ or more and 210 ℃ or less.
In order to exhibit strength, the pressure (line pressure) in the hot calendering treatment is preferably 50 to 250kN/m, and more preferably 80 to 150kN/m. In the case where the pressure is less than 50kN/m, the smoothness of the surface may be impaired, and in addition, if the speed is not reduced, the thickness may not become thin. In the case where the pressure exceeds 250kN/m, the sheet may not be able to withstand the pressure, resulting in breakage. The processing speed of the hot rolling is preferably 1 to 300m/min. The processing speed is set to 1m/min or more, thereby improving the work efficiency. By setting the processing speed to 300m/min or less, heat is conducted to the wet nonwoven fabric, and the actual effect of thermal welding is easily obtained. The number of times of the nip of the hot rolling is not particularly limited as long as heat can be conducted to the wet nonwoven fabric, and in the combination of the metal heat roll and the elastic roll, the nip may be performed 2 or more times in order to conduct heat from the front and back of the wet nonwoven fabric.
Electromagnetic wave shielding material
The electromagnetic wave shielding material of the present invention is characterized in that the nonwoven fabric for electromagnetic wave shielding material of the present invention is treated with a metal coating. That is, the electromagnetic wave shielding material of the present invention is characterized by comprising the nonwoven fabric for electromagnetic wave shielding material of the present invention and a metal coating.
In the present invention, examples of the metal coating treatment include electroless metal plating treatment, electroplating treatment, metal vapor deposition treatment, sputtering treatment, and the like. 1 or more kinds of processes selected from these processes may be performed. Among them, it is preferable to perform a plating process after the sputtering process in terms of the thin film, the low surface resistance, and the low possibility of peeling off the metal film. The metal coating may have 1 layer or a plurality of layers of 2 or more layers.
Examples of the metal used for the metal coating treatment include gold, silver, copper, zinc, aluminum, nickel, tin, and alloys thereof. Among them, 1 or more metals selected from gold, silver, copper, aluminum, nickel, and tin are preferable, and copper and nickel are more preferable in view of conductivity and manufacturing cost.
In the present invention, the metal coating treatment more preferably includes, in order, a treatment of forming a nickel coating by sputtering, a treatment of forming a copper coating by electroplating, and a treatment of forming a nickel coating by electroplating. First, a metal coating is formed on a wet nonwoven fabric by a sputtering process. The metal in the sputtering process is preferably nickel. After the sputtering treatment, the metal films are laminated by electroplating. The metal to be plated is preferably copper. Further, for rust prevention, a metal having good rust prevention properties such as nickel may be laminated on the outer layer thereof. The lamination method preferably uses an electroplating method.
The thickness of the electromagnetic wave shielding material of the present invention is preferably 15 μm or less, more preferably 13 μm or less, and still more preferably 12 μm or less. If the thickness of the electromagnetic wave shielding material is more than 15 μm, it may not be used for electronic devices, communication devices, electric appliances, and the like. The thickness of the electromagnetic wave shielding material is preferably 7 μm or more. The thickness is measured by JIS P8118:2014 was measured.
The surface resistance value of the electromagnetic shielding material of the present invention is preferably 0.03 Ω/\9633orless, more preferably 0.01 Ω/\9633orless. The electromagnetic wave shielding property at 40MHz to 18GHz is preferably 50dB or more. Further, the electromagnetic wave shielding property at 40MHz to 10GHz is preferably 60dB or more. Further, the electromagnetic wave shielding property at 40MHz to 1GHz is preferably 70dB or more.
Examples
The present invention will be described below with reference to examples, but the present invention is not limited to these examples at all. In the examples,% and parts are all on a mass basis unless otherwise specified.
Examples of nonwoven fabrics <1> for electromagnetic wave shielding material according to the present invention
[ example 1]
A uniform slurry for papermaking having a concentration of 1 mass% was prepared by dispersing 30 parts by mass of a drawn polyethylene terephthalate (PET) staple fiber having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm, 30 parts by mass of a drawn PET staple fiber having a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 5mm, and 40 parts by mass of an undrawn PET staple fiber having a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm in water by means of a pulper. The slurry for papermaking was used with a set air permeability of 275cm 3 /cm 2 Second, organization [ web: plain weave, lower mesh: stringy and flat structure]The inclined paper machine of (4) was manufactured by wet-laid papermaking, and the undrawn PET-based short fibers were heat-fused by a 135-cylinder dryer to exhibit strength, and the weight per unit area was 10g/m 2 The wet nonwoven fabric of (1). Further, the wet nonwoven fabric was subjected to a hot calendering treatment using a 1 nip hot calender comprising a dielectric heating nip roll (metal hot roll) and an elastic roll under conditions of a hot roll temperature of 200, a linear pressure of 100kN/m, and a treatment speed of 30 m/min, to prepare a nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm.
[ example 2]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 17 μm was produced in the same manner as in example 1, except that the drawn PET type staple fibers having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm were used in an amount of 10 parts by mass, a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 5mm were used in an amount of 50 parts by mass, and an unstretched PET type staple fibers having a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm were used in an amount of 40 parts by mass.
[ example 3]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 16 μm was produced in the same manner as in example 1, except that the drawn PET staple fiber had a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm (50 parts by mass), the drawn PET staple fiber had a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 5mm (10 parts by mass), and the undrawn PET staple fiber had a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm (40 parts by mass).
[ example 4]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 16 μm was produced in the same manner as in example 1, except that the drawn PET type staple fibers having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm were used in an amount of 45 parts by mass, a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 5mm, and an amount of unstretched PET type staple fibers having a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm were used in an amount of 45 parts by mass.
[ example 5]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 14 μm was produced in the same manner as in example 1, except that the drawn PET type staple fibers having a fineness of 0.1dtex (fiber diameter 3.0 μm) and a fiber length of 3mm were used in an amount of 30 parts by mass, the drawn PET type staple fibers having a fineness of 0.6dtex (fiber diameter 7.4 μm) and a fiber length of 5mm were used in an amount of 30 parts by mass, and the undrawn PET type staple fibers having a fineness of 0.2dtex (fiber diameter 4.3 μm) and a fiber length of 3mm were used in an amount of 40 parts by mass.
[ example 6]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 14 μm was produced in the same manner as in example 1 except that the drawn PET staple fibers had a fineness of 0.1dtex (fiber diameter: 3.0 μm), a fiber length of 3mm (10 parts by mass), a fineness of 0.3dtex (fiber diameter: 5.3 μm), a fiber length of 3mm (30 parts by mass), a fineness of 0.6dtex (fiber diameter: 7.4 μm), a fiber length of 5mm (30 parts by mass), and an unstretched PET staple fibers had a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm (30 parts by mass).
[ example 7]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 16 μm was produced in the same manner as in example 1 except that the drawn PET type staple fibers had a fineness of 0.3dtex (fiber diameter: 5.3 μm), a fiber length of 3mm (30 parts by mass), a fineness of 0.6dtex (fiber diameter: 7.4 μm), a fineness of 5mm (30 parts by mass), a fineness of 1.7dtex (fiber diameter: 12.0 μm), a fineness of 5mm (10 parts by mass), a fineness of 0.2dtex (fiber diameter: 4.3 μm), and a fiber length of 3mm (30 parts by mass).
[ example 8]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 14 μm was produced in the same manner as in example 1, except that the fibers had a fineness of 0.06dtex (fiber diameter: 2.4 μm), a fiber length of 3mm, 10 parts by mass of drawn PET-based staple fibers, a fineness of 0.3dtex (fiber diameter: 5.3 μm), a fiber length of 3mm, 30 parts by mass of drawn PET-based staple fibers, a fineness of 0.6dtex (fiber diameter: 7.4 μm), a fiber length of 5mm, and 30 parts by mass of undrawn PET-based staple fibers, a fineness of 0.2dtex (fiber diameter: 4.3 μm), and a fiber length of 3 mm.
[ example 9]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 16 μm was produced in the same manner as in example 1, except that the fibers had a fineness of 0.3dtex (fiber diameter 5.3 μm), a fiber length of 3mm (30 parts by mass of drawn PET-based staple fibers), a fineness of 0.6dtex (fiber diameter 7.4 μm), a fiber length of 5mm (30 parts by mass of drawn PET-based staple fibers), a fineness of 0.2dtex (fiber diameter 4.3 μm), a fiber length of 3mm (30 parts by mass of undrawn PET-based staple fibers), a fineness of 1.2dtex (fiber diameter 10.5 μm), and a fiber length of 5mm (10 parts by mass).
[ example 10]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 14 μm was produced in the same manner as in example 1, except that the fibers had a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm (15 parts by mass of drawn PET-based staple fibers), a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 5mm (15 parts by mass of drawn PET-based staple fibers), and a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm (70 parts by mass of undrawn PET-based staple fibers).
Comparative example 1
A nonwoven fabric for an electromagnetic shielding material having a thickness of 17 μm was produced in the same manner as in example 1, except that the drawn PET staple fibers having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm were used in an amount of 30 parts by mass, the drawn PET staple fibers having a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 5mm were used in an amount of 30 parts by mass, and the undrawn PET staple fibers having a fineness of 1.2dtex (fiber diameter: 10.5 μm) and a fiber length of 5mm were used in an amount of 40 parts by mass.
Comparative example 2
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm was produced in the same manner as in example 1, except that 60 parts by mass of the drawn PET-based staple fibers having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm and 40 parts by mass of the undrawn PET-based staple fibers having a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm were used.
Comparative example 3
A nonwoven fabric for an electromagnetic shielding material having a thickness of 21 μm was produced in the same manner as in example 1, except that the drawn PET staple fiber had a fineness of 1.7dtex (fiber diameter 12.0 μm) and a fiber length of 5mm (30 parts by mass), the drawn PET staple fiber had a fineness of 3.3dtex (fiber diameter 17.5 μm) and a fiber length of 5mm (30 parts by mass), and the undrawn PET staple fiber had a fineness of 0.2dtex (fiber diameter 4.3 μm) and a fiber length of 3mm (40 parts by mass).
Comparative example 4
A nonwoven fabric for an electromagnetic shielding material having a thickness of 18 μm was produced in the same manner as in example 1, except that 60 parts by mass of the drawn PET staple fibers having a fineness of 1.7dtex (a fiber diameter of 12.0 μm) and a fiber length of 5mm and 40 parts by mass of the undrawn PET staple fibers having a fineness of 0.2dtex (a fiber diameter of 4.3 μm) and a fiber length of 3mm were used.
Comparative example 5
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm was produced in the same manner as in example 1, except that 60 parts by mass of the drawn PET staple fibers having a fineness of 0.1dtex (fiber diameter: 3.0 μm) and a fiber length of 3mm and 40 parts by mass of the undrawn PET staple fibers having a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm were used.
The nonwoven fabrics for electromagnetic wave shielding materials prepared in examples and comparative examples were covered with a nickel film by an electroless plating method, and then a copper film and a nickel film were laminated in this order by an electroplating method to prepare an electromagnetic wave shielding material.
< evaluation >
[ transportability ]
The nonwoven fabric for electromagnetic shielding material was conveyed with a constant tension, and the wrinkle formation state at this time was evaluated according to the following criteria.
". Smallcircle" did not cause wrinkles, and the transportability was very good.
"Δ" the nonwoven fabric for an electromagnetic wave shielding material had wrinkles in a part thereof, but had no problem in transportability.
"×" wrinkles in the entire nonwoven fabric for electromagnetic shielding material to such an extent that it cannot be processed, and the transportability was poor.
[ electromagnetic wave shielding property (electric field) ]
The measurement was performed based on the electromagnetic wave shielding property (electric field) by the coaxial tube method. The measurement was carried out by the coaxial tube method 39D in the frequency range of 40MHz to 3GHz, and the measurement was carried out by the coaxial tube method GPC7 in the frequency range of 500MHz to 18 GHz. The frequency of 500MHz to 3GHz was measured by both of the coaxial tube method 39D and the coaxial tube method GPC7, and the numerical value was set at a low value.
The higher the numerical value described in the electromagnetic wave shielding property, the more excellent the electromagnetic wave shielding property.
[ Table 1]
The nonwoven fabrics for electromagnetic wave shielding materials of examples 1 to 10 were wet nonwoven fabrics containing 2 or more types of drawn polyester staple fibers having different fiber diameters and selected from among drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm, and undrawn polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less as essential components, and therefore, they were excellent in transportability and had excellent electromagnetic wave shielding properties. The nonwoven fabric for an electromagnetic wave shielding material of example 4 had a slightly decreased strength, but had no problem in transportability and was excellent in electromagnetic wave shielding properties.
In contrast, the nonwoven fabrics for electromagnetic wave shielding materials of comparative examples 1, 2, 3 and 4, which did not contain 2 or more kinds of drawn polyester staple fibers having different fiber diameters and unstretched polyester staple fibers having a fiber diameter of 3 μm or more and 5 μm or less as essential components selected from among the drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm, were poor in electromagnetic wave shielding properties. That is, it is considered that the nonwoven fabric for an electromagnetic wave shielding material of comparative example 1 in which the fiber diameter of the undrawn polyester based short fibers exceeds 5 μm, the nonwoven fabric for an electromagnetic wave shielding material of comparative example 3 containing 2 kinds of drawn polyester based short fibers different in fiber diameter from among the drawn polyester based short fibers having a fiber diameter of 12 μm or more, the nonwoven fabric for an electromagnetic wave shielding material of comparative example 4 in which the fiber diameter of the drawn polyester based short fibers is 12 μm, and the nonwoven fabric for an electromagnetic wave shielding material of comparative example 2 in which only 1 kind of drawn polyester based short fibers (fiber diameter of 5.3 μm) having the same fiber diameter are contained although the drawn polyester based short fibers having a fiber diameter of 3 μm or more and less than 12 μm are contained are reduced in multiple reflection loss.
In addition, the nonwoven fabric for an electromagnetic wave shielding material of comparative example 5, which contained only 1 type of the drawn polyester staple fibers (fiber diameter 3.0 μm) having the same fiber diameter, although containing the drawn polyester staple fibers having a fiber diameter of 3 μm or more and less than 12 μm, generated wrinkles during the conveyance of the web, and was poor in the conveyance property. It is considered that by including only the drawn polyester staple fibers having a small fiber diameter, the mesh becomes soft and easily elongates, and wrinkles easily occur.
Examples of nonwoven Fabric for electromagnetic wave Shielding Material <2> according to the invention
< evaluation >
(1) Surface resistance value
Assays were performed based on MIL DTL 83528C.
(2) Electromagnetic wave shielding property (electric field)
The measurement was performed based on the electromagnetic wave shielding property (electric field) by the coaxial tube method. The measurement was carried out by the coaxial tube method 39D in the frequency range of 40MHz to 3GHz, and the measurement was carried out by the coaxial tube method GPC7 in the frequency range of 500MHz to 18 GHz. The frequency of 500MHz to 3GHz was measured by both of the coaxial tube method 39D and the coaxial tube method GPC7, but the numerical value was low.
(3) Evaluation of peeling
An adhesive tape (Nitto (registered trademark) 31B tape, manufactured by ritong electrical corporation) was attached to an electromagnetic wave shielding material sample having a width of 25mm × a length of 150mm, and the sample was rolled 10 times at a speed of 300 mm/min using a 2kg roll. Then, the tape was peeled off at a speed of 1000 mm/min while forming an angle of 180 degrees with the sample. Evaluation was performed according to the following criteria.
< reference >
O: the test was conducted 3 times, and there were no breakage of the sample and no adhesion of the metal powder to the tape.
And (delta): the test was conducted 3 times, and the breakage of the sample and the adhesion of the metal powder to the tape occurred 1 to 2 times.
X: the test was conducted 3 times, and the breakage of the sample and the adhesion of the metal powder to the tape occurred 3 times.
[ example 11]
20 parts by mass of a drawn polyethylene terephthalate (PET) staple fiber having a fineness of 0.06dtex (fiber diameter: 2.4 μm) and a fiber length of 3mm, 40 parts by mass of a drawn PET staple fiber having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm, and 40 parts by mass of an undrawn PET staple fiber having a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm for a one-pack type binder were dispersed in water by a pulper to prepare a uniform pulp for papermaking having a concentration of 1 mass%. The slurry for papermaking was set to have an air permeability of 275cm 3 /cm 2 Second, organization [ web: plain weave, lower mesh: uneven structure]The inclined paper machine for papermaking of (1) is a wet nonwoven fabric produced by wet papermaking and thermally fusing an adhesive with undrawn PET-based staple fibers by a 135 ℃ drum dryer to develop strength. Further, a 1-nip hot-calendering apparatus comprising a dielectric heating jacket roll (metal heat roll) and an elastic roll was used, and the hot-rolled steel sheet was subjected to line-pressing at a hot-rolled temperature of 200 ℃The wet nonwoven fabric was subjected to a hot calendering treatment under conditions of a force of 100kN/m and a treatment speed of 100 m/min to prepare a wet nonwoven fabric having a basis weight of 6.5g/m 2 Density of 0.50g/cm 3 The nonwoven fabric for electromagnetic wave shielding material of (1).
Next, the nonwoven fabric for electromagnetic wave shielding material was covered with a nickel coating by electroless plating, and then a copper coating and a nickel coating were laminated in this order by electroplating to obtain an electromagnetic wave shielding material having a thickness of 17.5 μm.
[ example 12]
A wet-laid nonwoven fabric was obtained in the same manner as in example 11, except that 40 parts by mass of the drawn PET staple fiber having a fiber fineness of 0.06dtex (fiber diameter: 2.4 μm) and a fiber length of 3mm, 20 parts by mass of the drawn PET staple fiber having a fiber fineness of 0.3dtex (fiber diameter: 3.0 μm) and a fiber length of 3mm, and 40 parts by mass of the undrawn PET staple fiber for a one-pack type binder having a fiber fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm were blended. The wet nonwoven fabric was subjected to a hot calendering treatment in the same manner as in example 11 except that the treatment speed was set to 50 m/min, thereby obtaining a basis weight of 6.5g/m 2 Density of 0.63g/cm 3 The nonwoven fabric for an electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in example 11 to obtain an electromagnetic wave shielding material having a thickness of 16.0. Mu.m.
[ example 13]
A wet-laid nonwoven fabric was obtained in the same manner as in example 11, except that 60 parts by mass of the drawn PET staple fiber having a fineness of 0.06dtex (fiber diameter: 2.4 μm) and a fiber length of 3mm and 40 parts by mass of the undrawn PET staple fiber for a one-pack type adhesive having a fineness of 0.2dtex (fiber diameter: 4.3 μm) and a fiber length of 3mm were blended. The wet nonwoven fabric was subjected to a hot calendering treatment in the same manner as in example 11 except that the conditions of the linear pressure of 125kN/m and the treatment speed of 40 m/min were employed to prepare a wet nonwoven fabric having a basis weight of 6.5g/m 2 Density of 0.80g/cm 3 The nonwoven fabric for electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in example 11 to obtain an electromagnetic wave shielding material having a thickness of 15.5. Mu.m.
[ example 14]
Except that the unit area weight was set to 5.0g/m 2 Except for this, a wet nonwoven fabric was obtained in the same manner as in example 11. The wet nonwoven fabric was subjected to a hot calendering treatment in the same manner as in example 13 to prepare a wet nonwoven fabric having a density of 0.80g/cm 3 The nonwoven fabric for electromagnetic wave shielding material of (1). Next, the nonwoven fabric for electromagnetic wave shielding material was covered with a nickel coating by sputtering, and a copper coating and a nickel coating were sequentially laminated by plating to perform a metal coating treatment, thereby obtaining an electromagnetic wave shielding material having a thickness of 8.5 μm.
[ example 15]
Except that the unit area weight was set to 5.0g/m 2 Except for this, a wet nonwoven fabric was obtained in the same manner as in example 12. The wet nonwoven fabric was subjected to a hot calendering treatment in the same manner as in example 11 to prepare a wet nonwoven fabric having a density of 0.50g/cm 3 The nonwoven fabric for an electromagnetic wave shielding material of (1). Then, the electromagnetic wave shielding material nonwoven fabric was subjected to a metal coating treatment in the same manner as in example 14, thereby obtaining an electromagnetic wave shielding material having a thickness of 12.0 μm.
[ example 16]
Except that the unit area weight was set to 5.0g/m 2 Except for this, a wet nonwoven fabric was obtained in the same manner as in example 13. The wet nonwoven fabric was subjected to a hot calendering treatment in the same manner as in example 12 to prepare a wet nonwoven fabric having a density of 0.63g/cm 3 The nonwoven fabric for electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in example 14 to obtain an electromagnetic wave shielding material having a thickness of 10.0. Mu.m.
Comparative example 11
The same operation as in example 11 was carried out to obtain a basis weight of 10.0g/m, except that 60 parts by mass of the drawn PET-based staple fibers having a fineness of 0.3dtex (a fiber diameter of 5.3 μm) and a fiber length of 5mm and 40 parts by mass of the undrawn PET-based staple fibers for a one-pack type adhesive having a fineness of 1.2dtex (a fiber diameter of 10.7 μm) and a fiber length of 5mm were blended as fibers 2 The wet nonwoven fabric of (1). The wet nonwoven fabric was subjected to a hot calendering treatment in the same manner as in example 11 except that the conditions of a linear pressure of 135kN/m and a treatment speed of 40 m/min were adopted to prepare a densified nonwoven fabricDegree of 0.85g/cm 3 The nonwoven fabric for electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in example 14 to obtain an electromagnetic wave shielding material having a thickness of 16.0. Mu.m.
Comparative example 12
A basis weight of 10.0g/m was prepared in the same manner as in comparative example 11, except that the conditions of the line pressure of 100kN/m and the processing speed of 50 m/min were changed 2 Density of 0.63g/cm 3 The nonwoven fabric for an electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in comparative example 11 to obtain an electromagnetic wave shielding material having a thickness of 20.0. Mu.m.
Comparative example 13
A basis weight of 10.0g/m was prepared in the same manner as in comparative example 11, except that the conditions were changed to a linear pressure of 90kN/m and a processing speed of 100 m/min 2 And a density of 0.45g/cm 3 The nonwoven fabric for electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in comparative example 11 to obtain an electromagnetic wave shielding material having a thickness of 26.0. Mu.m.
Comparative example 14
The weight per unit area was 10.0g/m in the same manner as in comparative example 11 2 Density of 0.85g/cm 3 The nonwoven fabric for an electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in example 11 to obtain an electromagnetic wave shielding material having a thickness of 16.0. Mu.m.
Comparative example 15
The weight per unit area was 10.0g/m in the same manner as in comparative example 12 2 Density of 0.63g/cm 3 The nonwoven fabric for electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in comparative example 14 to obtain an electromagnetic wave shielding material having a thickness of 20.0. Mu.m.
Comparative example 16
A weight per unit area of 10.0g/m was prepared in the same manner as in comparative example 13 2 And a density of 0.45g/cm 3 The nonwoven fabric for an electromagnetic wave shielding material of (1). Then, a metal coating treatment was performed in the same manner as in comparative example 14 to obtain an electromagnetic wave shielding material having a thickness of 26.0. Mu.m.
[ Table 2]
A nonwoven fabric for an electromagnetic wave shielding material, which contains, as essential components, drawn polyester staple fibers having a fiber diameter of less than 3 [ mu ] m and undrawn polyester staple fibers having a fiber diameter of 3 [ mu ] m to 5 [ mu ] m, and has a basis weight of 7g/m 2 Below, density of 0.5-0.8 g/cm 3 Examples 11 to 16 of the electromagnetic wave shielding materials obtained by applying the metal coating treatment to the wet nonwoven fabric of (a) are excellent in electromagnetic wave shielding properties, and can achieve the effect that the metal coating is not easily peeled off. It is also found that the metal coating treatment includes a treatment for forming a nickel coating by sputtering, a treatment for forming a copper coating by plating, and a treatment for forming a nickel coating by plating in this order, and that the electromagnetic shielding material of examples 14 to 16 below has a thickness of 15 μm or less and a surface resistance value of 0.03 Ω/\ 9633and is more excellent in electromagnetic shielding properties and less likely to peel off the metal coating than the electromagnetic shielding materials of examples 11 to 13.
Comparative examples 11 to 16 are nonwoven fabrics for electromagnetic wave shielding materials, which comprise drawn PET-based staple fibers having a fiber diameter of 3 μm or more and undrawn PET-based staple fibers having a fiber diameter of more than 5 μm and have a basis weight of more than 7g/m 2 The electromagnetic wave shielding material obtained by subjecting the wet nonwoven fabric of (1) to a metal coating treatment. In comparative examples 11 and 13 in which the metal coating treatment sequentially included a treatment of forming a nickel coating by sputtering, a treatment of forming a copper coating by electroplating, and a treatment of forming a nickel coating by electroplating, the results of the electromagnetic wave shielding property and the peeling evaluation were poor. The electromagnetic wave shielding material of comparative example 12 was good in the electromagnetic wave shielding property and the peeling evaluation, but the thickness of the electromagnetic wave shielding material was 20.0 μm, and could not be made thin. In comparative examples 14 to 16, the metal coating treatment was performed by covering the copper film and the nickel film in this order by electroless plating treatment and then laminating the copper film and the nickel film in this order by electroplating treatment, and the result of the peeling evaluation was good, but the electromagnetic wave shielding property was poor.
Example of nonwoven Fabric for electromagnetic wave Shielding Material <3> according to the invention
[ example 21]
A uniform pulp for papermaking having a concentration of 1 mass% was prepared by dispersing 30 parts by mass of a drawn polyethylene terephthalate (PET) staple fiber having a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 5mm, 30 parts by mass of a drawn PET staple fiber having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm, and 40 parts by mass of an undrawn PET staple fiber for a parting binder having a fineness of 0.2dtex (fiber diameter: 4.3 μm), a fiber length of 3mm and a melting point of 246 ℃ in water by means of a pulper. The slurry for papermaking was set to have an air permeability of 275cm 3 /cm 2 Second, organization [ web: plain weave, lower mesh: uneven structure]The inclined paper machine of (2) is manufactured by wet-type papermaking, and the binder is thermally fused with undrawn PET-based short fibers by a 135 ℃ drum dryer to exhibit strength, and the basis weight is 10g/m 2 The wet nonwoven fabric of (1). Further, the wet nonwoven fabric was subjected to a hot calendering treatment using a 1 nip hot calender comprising a dielectric heating nip roll (metal hot roll) and an elastic roll under conditions of a hot roll temperature of 202 ℃, a linear pressure of 100kN/m, and a treatment speed of 40 m/min, to prepare a nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 2.1N/m.
[ example 22]
A nonwoven fabric for an electromagnetic wave shielding material having a thickness of 15 μm and a peel strength of 3.1N/m was produced in the same manner as in example 21, except that the hot roll temperature was 208 ℃.
[ example 23]
A nonwoven fabric for an electromagnetic wave shielding material having a thickness of 15 μm and a peel strength of 4.2N/m was produced in the same manner as in example 21, except that the hot roll temperature was set to 205 ℃.
[ example 24]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 3.5N/m was produced in the same manner as in example 23, except that the blend of the drawn polyester staple fibers was changed to 30 parts by mass of the drawn PET staple fibers having a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 3mm, and 30 parts by mass of the drawn PET staple fibers having a fineness of 0.1dtex (fiber diameter: 3.0 μm) and a fiber length of 3 mm.
[ example 25]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 3.7N/m was produced in the same manner as in example 23, except that the blend of the drawn polyester staple fibers was changed to 30 parts by mass of the drawn PET staple fibers having a fineness of 0.6dtex (fiber diameter: 7.4 μm) and a fiber length of 3mm, and 30 parts by mass of the drawn PET staple fibers having a fineness of 0.06dtex (fiber diameter: 2.4 μm) and a fiber length of 3 mm.
[ example 26]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 3.4N/m was produced in the same manner as in example 23, except that the blend of the drawn polyester staple fibers was changed to 30 parts by mass of the drawn PET staple fibers having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm, and 30 parts by mass of the drawn PET staple fibers having a fineness of 0.1dtex (fiber diameter: 3.0 μm) and a fiber length of 3 mm.
[ example 27]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 3.3N/m was produced in the same manner as in example 23, except that the blend of the drawn polyester staple fibers was changed to 30 parts by mass of the drawn PET staple fibers having a fineness of 0.3dtex (fiber diameter: 5.3 μm) and a fiber length of 3mm, and 30 parts by mass of the drawn PET staple fibers having a fineness of 0.06dtex (fiber diameter: 2.4 μm) and a fiber length of 3 mm.
[ example 28]
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 3.5N/m was produced in the same manner as in example 23, except that the blend of the drawn polyester staple fibers was changed to 30 parts by mass of the drawn PET staple fibers having a fineness of 0.1dtex (fiber diameter: 3.0 μm) and a fiber length of 3mm, and 30 parts by mass of the drawn PET staple fibers having a fineness of 0.06dtex (fiber diameter: 2.4 μm) and a fiber length of 3 mm.
Comparative example 21
A nonwoven fabric for an electromagnetic wave shielding material having a thickness of 15 μm and a peel strength of 1.8N/m was produced in the same manner as in example 21, except that the hot roll temperature was 198 ℃.
Comparative example 22
A nonwoven fabric for an electromagnetic wave shielding material having a thickness of 15 μm and a peel strength of 1.0N/m was produced in the same manner as in example 21, except that the hot roll temperature was changed to 195 ℃.
Comparative example 23
A nonwoven fabric for an electromagnetic wave shielding material having a thickness of 15 μm and a peel strength of 1.5N/m was produced in the same manner as in example 24, except that the hot roll temperature was 198 ℃.
Comparative example 24
A nonwoven fabric for an electromagnetic wave shielding material having a thickness of 15 μm and a peel strength of 1.0N/m was produced in the same manner as in example 25, except that the hot roll temperature was 198 ℃.
Comparative example 25
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 0.2N/m was produced in the same manner as in example 23 except that the blend of the fibers was 0.6dtex (fiber diameter 7.4 μm), 30 parts by mass of a drawn PET staple fiber having a fiber length of 3mm, 0.3dtex (fiber diameter 5.3 μm), 30 parts by mass of a drawn PET staple fiber having a fiber length of 3mm, 0.1dtex (fiber diameter 3.0 μm), and 30 parts by mass of a drawn PET staple fiber having a fiber length of 3mm, and 0.2dtex (fiber diameter 4.3 μm), and 10 parts by mass of an undrawn PET staple fiber for a monocomponent adhesive having a fiber length of 3mm and a melting point of 246 ℃.
Comparative example 26
A nonwoven fabric for an electromagnetic shielding material having a thickness of 15 μm and a peel strength of 1.8N/m was produced in the same manner as in example 23, except that the blend of the fibers was 0.6dtex (fiber diameter: 7.4 μm) and 10 parts by mass of the drawn PET-based staple fiber having a fiber length of 3mm, and 90 parts by mass of the undrawn PET-based staple fiber for a one-pack type adhesive having a fiber diameter of 0.2dtex (fiber diameter: 4.3 μm), a fiber length of 3mm, and a melting point of 246 ℃.
The electromagnetic wave shielding materials prepared in examples and comparative examples were subjected to alkali treatment as pretreatment for plating, and metal plating treatment of copper and nickel was performed by electroless plating to prepare electromagnetic wave shielding materials.
< evaluation >
[ peeling Strength ]
An electromagnetic wave shielding material was cut into 25mm × 200mm using a nonwoven fabric, and a double-sided tape (manufactured by NICIBAN, trade name: NW-R25, NICETACK (registered trademark) low-adhesion type) was attached to a liner (manufactured by Mitsubishi paper, trade name: N peel card (registered trademark) FSC authentication MX (450.0 g/m) 2 ) On the non-glossy surface thereof, a nonwoven fabric for an electromagnetic wave shielding material was laminated thereon, and a packaging tape (KAMOI KAKOSHI co., LTD, product name: no. 220W), a peel test was performed as shown in fig. 1, and the peel strength was measured. For the peel test, the following test was performed using a device name manufactured by SHIMPO (NIDEC-SHIMPO): the digital dynamometer FGC-2B was measured at a speed of 100mm/min with the distance between the jigs set to 1.8cm and the nonwoven fabric for the electromagnetic wave shielding material positioned at the center of the distance.
[ shedding resistance of fibers ]
An electromagnetic wave shielding material was cut into 25mm × 200mm using a nonwoven fabric, and the electromagnetic wave shielding material was subjected to reciprocal rubbing 5 times using a Billikenmos (japanese original: 12599125221246560. \\12531torr12473) cloth loaded with a 500gf weight (registered trademark) using a chemi-vibration type rubbing fastness tester, and evaluated according to the following criteria.
Fibers "very good" were not attached to the Billikenmos cloth.
The "o" fibers were hardly attached to the Billikenmos cloth.
The "Δ" fibers were slightly attached to the Billikenmos cloth, but there was no practical problem.
The "×" fibers adhere to the billenmos cloth, and the substrate may be broken in some cases.
[ frequency of defects ]
The defect frequency per 1000m was confirmed when the metal plating treatment was performed on the nonwoven fabric for an electromagnetic shielding material subjected to the alkali treatment as the pretreatment for plating.
". Circleincircle" 0 pieces/1000 m.
". Smallcircle" 1/1000 m.
". DELTA" 2/1000 m.
"×"3 or more/1000 m.
[ electromagnetic wave shielding (electric field) ]
The measurement was performed based on the electromagnetic wave shielding property (electric field) by the coaxial tube method. The measurement was carried out by the coaxial tube method 39D in the frequency range of 40MHz to 3GHz, and the measurement was carried out by the coaxial tube method GPC7 in the frequency range of 500MHz to 18 GHz. The frequency of 500MHz to 3GHz was measured by both of the coaxial tube method 39D and the coaxial tube method GPC7, and the numerical value was set at a low value.
The higher the numerical value described in the electromagnetic wave shielding property, the more excellent the electromagnetic wave shielding property.
[ Table 3]
The nonwoven fabrics for electromagnetic wave shielding materials of examples 21 to 28 have higher peel strength than the nonwoven fabrics for electromagnetic wave shielding materials of comparative examples 21 to 26, and therefore, have excellent resistance to fiber shedding, and also have a low defect frequency, and therefore, have a good yield and exhibit excellent electromagnetic wave shielding properties.
In comparative examples 21 to 23, the peel strength was the highest in example 23 in which the hot roll temperature was 205 ℃ and the resistance to fiber falling was improved. On the other hand, in comparative examples 21 to 24, since the hot roll temperature was less than 200 ℃, the nonwoven fabric for electromagnetic wave shielding material had low peel strength, poor fiber shedding resistance, and very many defect frequencies.
In comparative examples 25 and 26, since the content of the undrawn polyester staple fibers is less than 20% by mass or more than 80% by mass based on the whole fibers constituting the nonwoven fabric for electromagnetic wave shielding material and deviates from the ideal range, the nonwoven fabric for electromagnetic wave shielding material has low peel strength and poor fiber falling resistance although the hot roll temperature is 205 ℃.
Industrial applicability
The nonwoven fabric for an electromagnetic wave shielding material and the electromagnetic wave shielding material of the present invention are suitably used for electronic equipment applications, communication equipment applications, electric appliance applications, and the like. These devices and products include devices such as mobile phones, smart phones, mobile phones, personal computers, and mobile phones, boxes for storing these devices, and electric appliances such as televisions and washing machines. In particular, the electromagnetic shielding material of the present invention is suitably used by being fixed to a plastic case, a flexible printed circuit board, an electric wire cable, a connector cable, or the like by adhesion, pressure bonding, welding, winding, or the like.
Claims (5)
1. A nonwoven fabric for an electromagnetic wave shielding material, which is a wet nonwoven fabric, characterized by containing a stretched polyester staple fiber and an unstretched polyester staple fiber having a melting point of 220 ℃ or higher and 250 ℃ or lower, and by having a peel strength in the longitudinal direction of 2.0N/m or higher.
2. An electromagnetic wave shielding material, characterized in that the nonwoven fabric for electromagnetic wave shielding material according to claim 1 is treated with a metal coating.
3. The electromagnetic wave shielding material according to claim 2, wherein the metal coating treatment is 1 or more treatment selected from electroless metal plating treatment, electroplating treatment, metal evaporation treatment, and sputtering treatment.
4. The electromagnetic wave shielding material according to claim 2, wherein the metal coating treatment includes a treatment of forming a nickel coating by sputtering, a treatment of forming a copper coating by electroplating, and a treatment of forming a nickel coating by electroplating in this order.
5. The electromagnetic wave shielding material according to any one of claims 2 to 4, wherein the thickness of the electromagnetic wave shielding material is 15 μm or less, and the surface resistance value of the electromagnetic wave shielding material is
The following.
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| JP2019063014 | 2019-03-28 | ||
| CN201980060627.7A CN112703281B (en) | 2018-09-19 | 2019-09-11 | Nonwoven fabric for electromagnetic wave shielding material and electromagnetic wave shielding material |
| PCT/JP2019/035633 WO2020059582A1 (en) | 2018-09-19 | 2019-09-11 | Non-woven fabric for electromagnetic wave shielding materials and electromagnetic wave shielding material |
| CN202211194663.2A CN115538031B (en) | 2018-09-19 | 2019-09-11 | Nonwoven fabric for electromagnetic wave shielding material and electromagnetic wave shielding material |
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| CN113684608B (en) * | 2021-09-02 | 2023-03-28 | 前沿新材料研究院（深圳）有限公司 | Nonwoven fabric and electromagnetic shielding film |
| CN114059110A (en) * | 2021-11-01 | 2022-02-18 | 江门职业技术学院 | Radiation-proof polyester fiber surface treatment method and application |
| JP7219364B1 (en) | 2022-08-01 | 2023-02-07 | 大王製紙株式会社 | sheet nonwoven fabric |
| JP7323728B1 (en) * | 2023-01-31 | 2023-08-08 | 大王製紙株式会社 | Electromagnetic wave shielding substrate and electromagnetic wave shielding material containing wet-laid nonwoven fabric |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN112703281A (en) | 2021-04-23 |
| WO2020059582A1 (en) | 2020-03-26 |
| JP6669940B1 (en) | 2020-03-18 |
| JP2024086875A (en) | 2024-06-28 |
| TW202030392A (en) | 2020-08-16 |
| JP7016989B1 (en) | 2022-02-07 |
| JP2022043131A (en) | 2022-03-15 |
| CN112703281B (en) | 2023-01-06 |
| JPWO2020059582A1 (en) | 2021-01-07 |
| CN115538031B (en) | 2024-06-14 |
| KR20210057047A (en) | 2021-05-20 |
| JP2020167375A (en) | 2020-10-08 |
| CN115559148A (en) | 2023-01-03 |
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