JP2002314288A - Flame resistant conductive fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive fabric which has a superior electromagnetic shielding performance and flame resistance and which enables to reduce the thickness of a resin including a flame retardant and has a high flexibility. SOLUTION: The conductive fabric is made by forming resin layers including a flame retardant on both faces of a metal-covered fabric. The fabric has a cover factor of 1,400-2,500 and a 50-90% of free volume, and has such a structure that either warps or wefts which constitute the fabric are floats, with the other being sinks, and a floating height which is the average distance between the surface of the floats and the surface of the sinks is 3-30 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly flame-retardant conductive fabric used as an electromagnetic shielding material for electronic equipment and the like.

[0002]

2. Description of the Related Art Conventionally, conductive woven fabrics in which a metal coating is formed on the surface of synthetic fibers by a sputtering method, a metal vapor deposition method, various plating methods or the like have been known. Such conductive fabrics have been used for shielding electromagnetic waves leaking from electronic devices and for shielding electromagnetic waves entering from other electronic devices. However, in recent years, flame retardancy has also been required in the field of electronic devices such as home appliances and OA devices, and the conductive fabric used as a shielding material for these electronic devices also requires flame retardancy. It has become. However, in many cases, conductive woven fabrics formed by plating generally increase the flammability by using a metal as an oxidation catalyst. this is,
It is considered that the coated metal not only hinders the fire extinguishing action due to the melting of the fibers, but also improves the thermal conductivity due to the formed metal coating and promotes the spread of fire.

As a prior art, Japanese Patent Application Laid-Open No. 62-21870
Japanese Patent Laid-Open Publication No. H11-15083 discloses a method of imparting flame retardancy by applying a phosphorus compound flame retardant and a halogen compound flame retardant to a metal-adhered fiber. However, in this method, 19
Since the heat treatment is performed at 0 ° C., there is a possibility that conductivity may be deteriorated due to corrosion or alteration of a metal part. In addition, there is a method in which a resin obtained by adding a flame retardant to a metal-coated fiber is coated on one side to obtain a flame retardant effect. However, this method requires a large amount of coating in order to obtain high flame retardancy, and the coated resin film covers the metal on the surface, resulting in loss of surface conductivity. In JP-A-07-42079, a flame-retardant fiber woven fabric is metallized and its surface is coated with a urethane resin, and a mixture of an organic flame retardant and an inorganic flame retardant is coated thereon,
Further, a method of coating with a urethane resin is disclosed. However, in this method, the flame-retardant fiber material is limited.Furthermore, flame-retardant fibers are generally difficult to produce thin fibers due to their characteristics, and most of commercially available fibers are short fibers.
As a result, a thin woven fabric cannot be formed, and it is unsuitable for use as a shield component of an electronic component, which is a main use of the conductive woven fabric in terms of dust generation and fuzz. In addition, PVC fiber is flame-retardant, and fine denier yarn is produced.
The heat shrink start temperature is as low as 60 to 70 ° C, and 110 ° C
Problems tend to occur during plating and use, such as softening to a degree.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a conductive fiber having high flame retardancy while maintaining the conductive property of the conductive fiber woven fabric surface. Getting a woven fabric.

[0005]

The above object of the present invention has been attained by the following means. (1) In a conductive fabric formed by forming a resin layer containing a flame retardant on both surfaces of a metal-coated fabric, the cover factor of the fabric is 1400 to 2500, and the volume porosity of the fabric is 50 to 90%. And the surface resistance of the fabric surface is 1Ω /
□ a conductive woven fabric characterized by the following: (2) a structure in which one of a warp and a weft constituting the woven fabric floats to become a floating yarn, and the other sinks to become a sinking yarn. (1) The conductive fabric according to (1), wherein the floating height, which is the average interval between the yarn surfaces, is 3 to 30 μm, (3) the conductive fabric according to (1) or (2), wherein the thickness of the fabric is 40 to 250 μm. (4) The woven fabric is composed of a polyester-based yarn that does not contain a flame retardant
(1) to (3) the conductive woven fabric according to any one of (1) to (5), wherein the flame retardant is formed from a mixture of three kinds of an organic bromo compound, a phosphoric ester and antimony trioxide.
The conductive woven fabric according to any one of the above. (6) The conductive fabric according to any one of (1) to (5), wherein the resin forming the resin layer is a urethane resin.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to obtain a high degree of flame retardancy, it is important to have sufficient voids so that the resin easily penetrates into the inside of the fabric when impregnating the resin with the flame retardant added.
However, if the gap is too large, the electromagnetic wave shielding property is impaired.

Further, in order to obtain high flame retardancy, it is desirable that the flame retardant resin permeates between the filaments constituting the woven fabric. For that purpose, the cover factor of the woven fabric needs to be in the range of 1400 to 2500, and particularly preferably in the range of 1500 to 2300. If the cover factor is smaller than 1400, the gap between the yarns is large, and a sufficient shielding effect may not be obtained. On the other hand, if the cover factor is larger than 2500, the penetration of the resin between the yarns becomes poor, so that it is difficult to obtain the flame retardant effect, and the texture of the fabric becomes hard, and the weaving property may be deteriorated. Here, the cover factor refers to the ratio of the area occupied by the yarn to the area of the woven fabric, and is calculated as follows. Cover factor (CF) = warp density (book / inch) x (total fineness of warp (dtex)) ^1/2 + weft density (book / inch) x
(Weft total fineness (dtex)) ^1/2

[0008] The volume porosity of the woven fabric is 50 to 90%.
It is necessary to be within the range. The volume porosity of a woven fabric is a percentage (%) obtained by dividing a volume (Vv) obtained by subtracting a volume (v) occupied by a synthetic fiber present in a certain volume (V) of the woven fabric by the certain volume (V) = [｛(V−v) /
(V)｝ × 100], and the larger the value, the smaller the volume occupied by the synthetic fiber. If the volume porosity of the woven fabric is 50% or less, the resin penetration into the yarn gaps becomes poor, and sufficient flame retardancy may not be obtained. If the volume porosity exceeds 90%, sufficient shielding properties may not be obtained even if a metal coating is formed. By adopting such a woven structure, the flame-retardant resin easily adheres to the floating height portion, and the flame-retardant resin easily penetrates into the gaps between the filaments. A burning effect can be obtained.

According to the present invention, as described above, when the cover factor and the volume porosity of the woven fabric satisfy the specific ranges, the resin containing the flame retardant enters between the single yarns constituting the filament, thereby providing a sufficient amount. Flame retardancy can be secured,
Furthermore, since the resin layer can be made thinner, it is possible to provide a conductive fabric which does not impair the flexibility of the fabric.

Generally, a woven fabric does not have a structure in which one of a warp and a weft sinks and the other floats, and often has a floating height close to zero. However, in the present invention, the floating height is 3 μm to 30 μm.
m, particularly preferably 5 to 15 μm. When the floating height is less than 3 μm, the amount of the resin containing the flame retardant that can be applied while satisfying the surface conductivity decreases, and when the floating height is more than 30 μm, the weaving property of the fabric deteriorates. Here, the floating height refers to the difference between the surface heights of the warp and the weft when cut in a direction perpendicular to the fabric surface and viewed from the cross-sectional direction, as shown in FIG. In order to create a woven fabric with such a floating height, one yarn should be contracted more than the other by changing the tension during weaving and pre-plating, and the thickness of the warp and weft. Alternatively, the floating height can be made by increasing the thickness. Further, the height can be further increased by combining two or more of the above three methods (high tension, high shrinkage, and thick yarn).

[0011] The thickness of the woven fabric made using the above-described yarn is
It is preferably from 40 to 250 μm. If the thickness of the woven fabric is less than 40 microns, the strength of the woven fabric may not be sufficient. If the thickness is 250 μm or more, the thickness of the product becomes large, and it is difficult to use the electronic device with reduced weight and size. , Which is not economically favorable.

The yarn used in the woven fabric of the present invention is preferably composed of a yarn mainly composed of polyester filament in consideration of workability and durability. All may be composed of polyester, and also synthetic fibers such as polyamide, acrylic and polyolefin, regenerated fibers such as rayon, mixed with semi-synthetic fibers such as acetate, entangled,
Processing such as twisting may be performed. "Consisting of yarn mainly composed of polyester filament" means that, even when polyester filament yarn and other types of fibers are mixed or twisted, the maximum percentage (weight ratio) of polyester filaments among the constituent fiber types Means to occupy. Preferably, the polyester filament content is 50% by weight or more. Further, as the form of the yarn, either raw yarn or crimped processed yarn can be used. Further, one or a plurality of warps and / or wefts may be mixed alternately. However, so that the flame-retardant resin is easily impregnated between the single yarns constituting the filament,
It is preferable to use a processed yarn for at least one of the warp and the weft. Further, the cross-sectional shape of the yarn may be a round cross-section, a hollow cross-section, a W-shaped cross-section or the like. It is preferable to use a multifilament having a total fineness of 33 to 222 dtex.

The metal to be coated includes gold, silver, copper, zinc, nickel, and alloys thereof. Copper and nickel are preferable in consideration of conductivity and production cost.
The coating layer formed of these metals is preferably one layer or two layers. If the number of layers is three or more, the metal coating layer becomes thick, and the conductive fabric may be hardened, and the processing cost is further increased. When the metal coating layer is formed into two layers, the same kind of metal may be formed into two layers, or different metals may be stacked. These can be appropriately set in consideration of the required shielding properties and durability. In addition, the metal film forming method is a vapor deposition method, a sputtering method, an electroplating method,
An electroless plating method and the like can be mentioned, but from the viewpoint of uniformity of the formed metal film and productivity, an electroless plating method or a combination of the electroless plating method and the electroplating method is preferably used. The metal coating amount is suitably 5 to 50 g / ^{m 2,} preferably not 10 to 40 g / ^{m 2,} more preferably a 15 to 30 g / ^{m 2.} If the amount is less than 5 g / m ² , the surface conductivity and the shielding property are impaired, and 50 g / m ^2.
If the number is larger, the texture becomes harder and the cost is disadvantageous.

The resin applied to the woven fabric on which the metal coating layer is formed is composed of a urethane resin and a flame retardant. The resin application amount is preferably 15 to 80 g / m ^2, more preferably ² to 80 g / m 2.
0 to 60 g / m ² . The amount of resin to be applied is 15 g /
m ² less and no sufficient flame retardancy is obtained from the amount of the resin to impart the surface conductivity is more than 80 g / m ² is impaired, which is disadvantageous economically. The method of applying the resin includes a padding method and a coating method, and any method may be used. Urethane resins are superior to acrylic resins and ester resins in terms of flame retardancy, frictional strength, and flexibility. Further, among urethane resins, ester-based urethane which is hardly yellow-modified is preferable in terms of durability and economic efficiency. As these urethane resins, aromatic isocyanates such as diphenylmethane diisocyanate (MDI) and tolylene diisocyanate (TDI) are preferably used as isocyanates, and polyester diols composed of aliphatic carboxylic acids and glycol components are preferably used as polyols. . The viscosity of the applied resin can be appropriately set by a coating method.

Examples of the flame retardant that can be used in the present invention include halogen-based flame retardants, phosphorus-based flame retardants, and antimony trioxide. When a halogen-based flame retardant and a phosphorus-based flame retardant are used in combination, an excellent flame-retardant effect is exhibited by synergistic action, and antimony trioxide enhances this synergistic effect, so that halogen-based flame retardant, phosphorus-based flame retardant and antimony trioxide are used. A mixture of three is preferably used.

The halogen-based flame retardant that can be used in the present invention includes:
Although it is roughly classified into a bromo flame retardant and a chloro flame retardant, in the present invention, it is preferable to use a bromo flame retardant. Further, bromo flame retardants are classified into organic bromo compounds and inorganic bromo compounds, and in the present invention, it is particularly preferable to use organic bromo compounds. Organic bromo compounds refer to organic compounds substituted with one or more bromine atoms. However, phosphoric esters containing one or more bromine atoms are excluded. Examples of the organic bromo compound include hexabromobenzene, hexabromobisphenyl ether, tribromophenol, decabromobiphenyl ether, Pigalol SR103 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and Pigalol SR
700 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and the like. In the present invention, hexabromobenzene and decabromobiphenyl ether are preferred organic bromo compounds.

The phosphorus-based flame retardants are classified into inorganic phosphates, nitrogen-containing phosphorus compounds, non-halogen phosphate esters, halogen-containing phosphate esters, and the like. Examples of the inorganic phosphate include ammonium polyphosphate and the like. Examples of the nitrogen-containing phosphorus compound include phosphotonitrile chloride derivatives and phosphonoamide compounds. Non-halogen phosphates include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate,
Examples include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, and the like. The halogen-containing phosphoric acid ester is a phosphoric acid ester containing one or more halogen atoms (including a bromine atom) in one molecule. As the halogen atom, a bromine atom or a chlorine atom is preferable. Since the halogen atom and the phosphorus atom work synergistically with each other, a strong flame retardant effect is exhibited. Examples of the halogen-containing phosphoric acid ester include tris (chloroethyl) phosphate, tris (dichloropropyl) phosphate, tris (chloropropyl) phosphate, and bis (2,3-dibromopropyl).
2,3-dichloropropyl phosphate, tris (2,
Examples thereof include 3-dibromopropyl) phosphate and bis (chloropropyl) monooctyl phosphate. In the present invention, tris (chloroethyl) phosphate and bis (chloropropyl) monooctyl phosphate can be preferably used. In the present invention, a phosphate ester substituted with one or more bromine atoms is classified as a halogen-containing phosphate ester. In the present invention, the phosphate ester is a non-halogen phosphate ester,
Alternatively, it is preferable to use a halogen-containing phosphoric acid ester. Specific examples of other flame retardants that can be used in the present invention are illustrated in Hitoshi Nishizawa, "Flame Retardation of Polymers: Chemistry and Practical Techniques", Taiseisha, the second edition supplemented on July 20, 1989. Have been.

The ratio of the flame retardant to the resin is 200 to 400% by weight, preferably 300 to 200% by weight.
~ 350%, phosphate ester 50 ~ 150%, preferably 80 ~ 120%, antimony trioxide 60 ~ 170
%, Preferably 100 to 150%. If the ratio is higher than this, the resin film becomes brittle, and if the ratio is lower, sufficient flame retardancy cannot be obtained. As a flame retardant, remarkable flame retardancy can be obtained by combining three kinds of organic bromide compounds, phosphate esters and antimony trioxide. This is because particularly excellent synergistic effects can be obtained by using these three types of flame retardants in combination.

[0019]

EXAMPLES (Evaluation method) The evaluation methods of the woven fabrics described in the examples and comparative examples are as follows. Volume porosity of woven fabric A sample of 10 cm × 10 cm is cut from the woven fabric, the thickness of the woven fabric is measured, and the apparent volume V (cm ³ ) of the sample is obtained. Further, the weight (g) of the sample is measured, the volume v (cm ³ ) occupied by the polyester fiber is determined from the specific gravity (ρ) of the polyester fiber, and the volume porosity (%) of the woven fabric is calculated by the following equation. Volume porosity (%) = {(V−v) / (V)} × 100 Flame retardancy evaluation Evaluated by ULTM VTM-0. Surface resistance Clip resistance electrode width 10c, using a resistance measurement device Milliohm High Tester 3220 manufactured by HIOKI Electric Co., Ltd.
m, and the resistance value at a distance between the electrodes of 10 cm was measured. The unit is Ω / □. Shielding performance evaluation A measurement cell similar to the one devised by the Ikoma Radio Measurement Center of the Kansai Electronic Industry Promotion Center was created, and a spectrum analyzer with a tracking generator HP8591EM manufactured by Hewlett-Packard Co., Ltd. for 10 MHz to 1 G was used.
Hz oscillation was received by the above-mentioned cell receiving section via a measurement sample, and measured by a spectrum analyzer. The unit is dB
It is. The thickness of the fabric was measured using a Peacock (manufactured by TECLOCK Co., Ltd.). The unit is μm. Flexibility The flexibility of the sample was measured by the JIS L 1096 A method (45 ° cantilever method). The unit is mm.

Example 1 Warp yarns of 56 dtex / 24f
A plain woven fabric using 56 dtex / 36f polyester processed yarn for the polyester raw yarn and the weft is refined, dried and heat-treated to obtain a warp density of 166 yarns / inch, a weft density of 114 yarns / inch, a fabric thickness of 85 μm, a volume porosity of 70%, A woven fabric having a floating height of 8 μm and a cover factor of 2095 was obtained. Using this woven fabric, subsequently, 0.3 g / L of palladium chloride,
It was immersed in an aqueous solution of 40 ° C. containing 30 g / L of stannous chloride and 300 ml / L of 36% hydrochloric acid for 2 minutes, and then washed with water. continue,
It was immersed in borofluoric acid having an acid concentration of 0.1 N at 30 ° C. for 5 minutes, and then washed with water. Next, it was immersed in an electroless copper plating solution consisting of 7.5 g / L of copper sulfate, 30 ml / L of 37% formalin, and 85 g / L of Rochelle salt at 30 ° C. for 5 minutes, and washed with water. Then, nickel sulfamate 300g / L, boric acid 3
0 g / L, nickel chloride 15 g / L, pH 3.7, electro nickel plating solution at 35 ° C., 10 minutes, current density 5 A / L
immersed in dm ² and then washed with water as a laminate of nickel. The fabric was plated with 10 g / m ² copper and 4 g / m ² nickel. The weight of the obtained conductive fabric was 64 g / m ² . The following formula 1 resin was applied to both surfaces of the obtained conductive fabric by a floating knife method, and dried at 130 ° C. The coating amount was 20 g / m ² on each side.
Table 1 shows the performance evaluation results. Formulation 1 Chrisbon 5116EL 100 parts (Dainippon Ink & Chemicals, Inc., urethane resin) Decabromodiphenyl ether 90 parts Tris (chloroethyl) phosphate 40 parts Antimony trioxide 30 parts Methyl ethyl ketone is added to adjust the viscosity to 8000 cps.

(Example 2) A warp and a weft have 56 dt.
A plain fabric using ex / 36f polyester processed yarn is scoured, dried and heat-treated to obtain a warp density of 120 yarns / inch, a weft yarn density of 120 yarns / inch, a fabric thickness of 100 μm, a volume porosity of 80%, a floating height of 5 μm, and a cover. Factor 1796
Was obtained. Using this woven fabric, a plating treatment was subsequently performed in the same manner as in Example 1, and the woven fabric contained 10 g / m ^{2 of} copper,
Nickel was plated at 4 g / m ² . The weight of the obtained conductive fabric was 58 g / m ² . Further, the resin of Formula 1 shown above was applied to both surfaces of the obtained conductive fabric by a floating knife method, and dried at 130 ° C. Coated amount was ^{15g / m 2, 20g / m} 2 in terms of其people. Table 1 shows the performance evaluation results.

Example 3 The resin of Formula 1 was applied to the woven fabric plated in Example 2 by a dipping method, and both surfaces were simultaneously removed by a knife doctor method to remove excess resin on the surface of the woven fabric. And dried. The coating amount was 30 g / m ² . Table 1 shows the performance evaluation results.

Comparative Example 1 The resin of Formula 1 described above was applied to one surface of the conductive fabric used in Example 1 by a floating knife method and dried at 130 ° C. Coating amount is 3
g / m ² . Next, the resin of the above-described formula 1 was applied to the other surface by a floating knife method.
Dried at 0 ° C. The coating amount was 70 g / m ² . Table 1 shows the performance evaluation results.

(Comparative Example 2) 90 dt for warp and weft
A plain woven fabric using ex / 24f polyester filament yarn is scoured, dried and heat-treated to give a warp density of 175 yarns /
Inch, weft density 128 yarns / inch, fabric thickness 85 μm, volume porosity 35%, floating height 8 μm, cover factor 287
4 were obtained. Using this fabric, Example 1
The plating process is performed in the same manner as in
m ² , nickel was plated at 4 g / m ² . Further, the resin of Formula 1 described above was applied to both surfaces of the obtained conductive fabric by a floating knife method, and dried at 130 ° C. Coated amount was respectively ^{3g / m 2, 7g / m} 2. Table 1 shows the performance evaluation results.

(Comparative Example 3) 56 dtex / 24f for warp
A plain woven fabric of 56dtex / 36f polyester processed yarn is refined, dried and heat-treated for polyester raw yarn and weft yarn, and the warp density is 110 yarns / inch, the weft density is 70 yarns / inch, the fabric thickness is 60 μm, the volume porosity is 85%, and the floating height 1 μm,
A woven fabric with a cover factor of 1347 was obtained. Using this woven fabric, plating was performed in the same manner as in Example 1, and the woven fabric was plated with copper at 10 g / m ² and nickel at 4 g / m ² . The obtained conductive fabric had a basis weight of 64 g / m ² . The resin of the above Formula 1 was applied to both surfaces of the obtained conductive fabric by a floating knife method, and dried at 130 ° C. The coating amount was 20 g / m ² , and the performance evaluation results are shown in Table 1.

[0026]

[Table 1]

[0027]

According to the present invention, a conductive fabric excellent in flame retardancy can be obtained, and a conductive fabric excellent in flexibility while maintaining surface conductivity on both surfaces of the fabric can be obtained. Further, even if a flame retardant is applied, the quality of the surface of the metal-coated fabric is not impaired. Furthermore, by using polyester fiber woven fabric,
A conductive woven fabric having a thin texture and a soft texture can be obtained, and less dust is generated from the woven fabric, so that a product excellent as a shielding material for electronic components can be provided.

[Brief description of the drawings]

FIG. 1 is an example of a schematic sectional view of a woven fabric used in the present invention.

FIG. 2 is a schematic view in which a resin is applied to the woven fabric of FIG. 1;

FIG. 3 is an enlarged schematic view of a square portion surrounded by a wavy line in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Floating yarn 2 ... Sunk yarn 1 '... Single yarn which comprises a floating yarn 2' ... Single yarn which comprises a sinking yarn 3 ... Resin containing a flame retardant aa '... Floating yarn surface b-b '... Sinking surface X ... Floating yarn height

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) D06M 13/292 D06M 11/00 D 15/564 11/12 F term (Reference) 4L031 AA18 AB32 BA04 BA09 CB12 DA15 DA16 4L033 AA07 AB05 AC05 AC06 AC15 BA05 BA39 CA50 4L048 AA20 AB07 AB21 BA01 BA02 CA00 CA15 DA24 EB00 5E321 AA21 BB23 BB41 BB44 GG05 GH10

Claims (6)

[Claims] 1. A conductive woven fabric comprising a metal-coated woven fabric having a resin layer containing a flame retardant on both sides, wherein the woven fabric has a cover factor of 1400 to 2500 and a volume porosity of the woven fabric of 50 to 50. 90%, and the surface resistance of the woven fabric surface is 1 Ω / □ or less. 2. A structure in which one of a warp and a weft constituting a woven fabric floats to become a floating yarn, and the other sinks to become a sinking yarn.
The floating height, which is the average distance between the surface of the floating yarn and the surface of the sinking yarn, is 3 to 3.
The conductive woven fabric according to claim 1, which has a thickness of 0 µm. 3. The conductive woven fabric according to claim 1, wherein the woven fabric has a thickness of 40 to 250 μm. 4. The conductive woven fabric according to claim 1, wherein the woven fabric is made of a polyester-based yarn containing no flame retardant. 5. The conductive fabric according to claim 1, wherein the flame retardant is formed from a mixture of three kinds of an organic bromo compound, a phosphoric ester and antimony trioxide. 6. The conductive fabric according to claim 1, wherein the resin forming the resin layer is a urethane resin.