JPH025319B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a flexible sheet that effectively eliminates electrical and electromagnetic interference. BACKGROUND OF THE INVENTION Conventionally, flexible sheets made of various synthetic resins or synthetic or natural rubber have been used as covering materials for equipment covers and other flexible sheets, and these are often reinforced with fiber materials. However, these sheets are electrically insulating in nature and generally have ^a
It has a specific resistance value of 10 ¹⁷ Ω·cm, and often 10 ¹² Ω·cm or more. However, in recent years, as the development of electrical equipment has progressed, the occurrence of electrical interference and radio wave interference has become a serious problem, and there is a demand for the development of drastic measures to solve the electrical problems with such sheets. SUMMARY OF THE INVENTION The present invention has been completed as a result of studies to satisfy the above requirements, and is capable of effectively suppressing electrical and electromagnetic interference and providing extremely favorable responses to various situations. This provides a flexible sheet that can According to the present invention, a flexible sheet is provided, and this sheet includes a conductive sheet portion and an insulating sheet portion laminated and bonded thereto. DETAILED DESCRIPTION OF THE INVENTION In the flexible sheet of the present invention, it is preferable that insulating sheet portions are formed on both the front and back surfaces of the conductive sheet portion. In addition, the specific resistance value of the above-mentioned conductive sheet portion (hereinafter referred to as the conductive sheet portion) is 18 ⁸ Ω・cm or less, especially
It is preferably 10 ⁵ Ω·cm or less, and may be 10 ¹ Ω·cm or less depending on the application. The resistance value of the insulating sheet portion is preferably 10 ⁸ Ω·cm or more, more preferably 10 ¹⁰ Ω·cm or more, and particularly preferably 10 ¹⁰ to 10 ¹⁸ Ω·cm. In order to achieve the objectives of the invention, the sheets of the invention must be flexible in nature. In the case of such flexible sheets, it is possible to achieve the purpose by applying a conductive coating material to the surface of a normal non-conductive sheet; Adhesion to the surface becomes a problem, and flexible sheets are easily peeled off due to severe bending, making it difficult to obtain a sufficiently effective sheet. Furthermore, when applying conductive paint, there are many limitations in terms of hue, making it difficult to obtain colorful sheets. Therefore, in the present invention, a flexible sheet is obtained by laminating and bonding a sheet-like substrate having at least one layer of conductive sheet portion and at least one layer of insulating sheet portion.
When manufacturing the sheet of the present invention, it is generally preferable to blend a conductive material into a matrix made of synthetic resin, synthetic rubber, or natural rubber and adjust the resistance to a predetermined value to make the sheet. It is also possible to form the sheet solely from conductive material if the requirements are met. As mentioned above, the conductive sheet portion and the insulating sheet portion constituting the flexible sheet of the present invention include:
It is preferable to use a matrix made of synthetic resin, synthetic rubber or natural rubber; examples of preferred synthetic resins include polyvinyl chloride (PVC), polyurethane, ethylene-vinyl acetate copolymer, isotactic polypropylene, polyethylene, Examples include acrylonitrile, polyester and polyamide, and other known materials. Examples of preferable synthetic rubbers include styrene-butadiene rubber (SBR), chlorosulfonated polyethylene rubber,
Examples include polyurethane rubber, butyl rubber, isoprene rubber, and other known materials. The most preferred synthetic resin is PVC, which may contain plasticizers, fillers, colorants, stabilizers and/or other modifiers. Further, depending on the use and purpose, these matrices may contain bubbles or may be porous. The conductive material that is mixed into the matrix of these conductive sheet parts to control the resistance value of each sheet part may be a liquid, powder, fiber, foil, wire or sheet conductive material. Materials such as carbon black, metals such as Al,
Au, Ag, Pt, Cu, Cr, Ni, Zn, Ti, Pb, Sn,
Pd or compounds thereof or Ni-Cr alloys or other conductive compounds such as indium oxide. The blending amount of the conductive substance is determined by taking into account the conductivity and properties inherent to the substance and the desired degree of conductivity, but it is preferably at least 5% by weight, and preferably 10 to 70% by weight. is even more preferable. Of course, the blending amount of the conductive material is not limited to 70% by weight or less, and especially in the case of the conductive sheet portion, it is necessary to have the desired flexible sheet properties (strength, flexibility, appearance, etc.). It may be more than 70% by weight as long as it is present. For reference, the specific resistance values of various materials are shown below.

[Table] As described above, the flexible sheet made of the above-mentioned materials is a combination of a conductive sheet portion and an insulating sheet portion, and the structure of this sheet will be explained in more detail below. In the accompanying drawings, FIGS. 1 and 2 are sectional views each schematically showing an example of a flexible sheet according to the present invention. The flexible sheet shown in FIG. 1A has an insulating sheet portion 2 formed on both sides of a sheet base consisting of a conductive sheet portion 1. In the flexible sheet shown in FIG. 1B, the conductive sheet portion An insulating sheet portion 2 is formed only on one side of a sheet-like substrate made of 1. On the other hand, in the flexible sheet shown in FIG. 2, a sheet-like base is formed from a plurality of layers of conductive sheet parts 1 and an insulating sheet part 2 laminated and bonded between them. It is formed to surround this. In the case of the configuration shown in Fig. 2, safety and effectiveness can be reliably achieved when used in an environment where the usage conditions are different for the front and back sides, and it is preferable especially under harsh usage conditions. . The flexible sheet of the present invention having such a structure is preferably combined with a reinforcing material. Fibrous base fabrics are common as reinforcing materials, and useful fibrous base fabrics include natural fibers such as cotton and linen, inorganic fibers such as glass fiber, and recycled fibers such as viscose rayon. , kyupra, semi-synthetic fibers such as g- and triacetate fibers, and synthetic fibers such as nylon 6, nylon 66, polyester (such as polyethylene terephthalate) fibers, aromatic polyamide fibers, acrylic fibers, polyvinyl chloride fibers and polyolefins. Some are made of at least one type selected from fibers, etc. The fibers in the base fabric may be in any form such as short fiber spun yarn, long fiber thread, split yarn, or tape yarn, and the base fabric may be a woven fabric, knitted fabric, nonwoven fabric, paper-like material, or a composite fabric thereof. It may be either. Generally, the fibers used in the sheet of the present invention are preferably polyester fibers, and these fibers are preferably in the form of long fibers (filaments). The fibrous base fabric is useful for maintaining the resulting sheet's mechanical strength at a high level. In addition, useful fabrics include fabrics made of twill weave, plain weave, and other general structures, but the tear strength of the product, the flexibility of bending in multiple directions,
Considering the durability of the adhesion of the conductive sheet part and the insulating sheet part material to the base fabric, the crack resistance of the resin or rubber layer in cold weather, the light weight, etc., special structured woven fabrics as described below are particularly preferably used. It will be done. In addition, when the content of conductive material is high, the conductive sheet portion tends to become hard, and if plain fabric, nonwoven fabric, or paper-like material is used as a reinforcing support for a sheet containing such material, the entire sheet becomes hard. However, in such a case, it is extremely preferable to use a specially structured woven base fabric because it can cover the hardness and provide a suitably flexible sheet. The special structure woven base fabric useful for the flexible sheet of the present invention includes natural fibers such as cotton, linen, etc., inorganic fibers such as glass fiber, recycled fibers such as viscose rayon, Kyupra, etc., semi-synthetic fibers, and synthetic fibers such as nylon 6, nylon 66, polyester (such as polyethylene terephthalate) fibers, aromatic polyamide fibers, acrylic fibers, polyvinyl chloride fibers and polyolefin fibers. It consists of at least one type. The fibers in the base fabric may be in any form such as short fiber spun yarn, long fiber yarn, split yarn, or tape yarn. These are arranged in parallel to each other, and the warp and weft layers thus formed are laminated so as to intersect with each other, and are loosely connected by long leno threads at the intersections of the warp and weft threads. The leno thread is made of polyester, nylon, aromatic polyamide and other known synthetic fibers, glass fiber,
It may be selected from steel fibers and other known inorganic fibers, with polyamide filament yarns being particularly preferred. Now, for example, as warp and warp yarns, we are using tensile strength single yarns.
When 1.3Kg of Vinylon 10S/1 spun yarn is used, the tensile strength per unit denier is as a leno yarn.
20g of aromatic polyamide filament yarn is used, and if yarns of the same material are used in consideration of ease of sheet processing, for example, polyester filament yarn with a tensile strength of 8g per unit denier is used as the warp and warp yarns. Also, 10g of polyester filament yarn is used as the leno thread. A particularly preferable structure of the special structure fabric for use in the present invention is as follows:
30381, a warp layer consisting of a large number of warps arranged in parallel to each other, a weft layer consisting of a large number of wefts arranged in parallel to each other so as to be perpendicular to the warps, and the warp and weft. and a tangle thread that entangles and connects them at their intersections. The leno yarn is longer than the warp and weft, and therefore loosely connects the warp and weft, and has at least one of its tensile strength, tensile elongation, and breaking work as compared to the warp and weft. The adhesion force to the resin material is preferably greater than that of the warp and weft and/or smaller than that of the warp and weft. As the leno yarn, yarns having the characteristics shown below are particularly preferred. That is, (i) a leno yarn whose strength is 10% or more per unit denier than the warp and weft yarns constituting the base fabric. (ii) Leno yarn whose breaking work is 10% or more greater than the warp and weft yarns that make up the base fabric. (iii) Leno yarn whose elongation at break is 5% or more greater than the warp and weft yarns that make up the base fabric. (iv) Leno yarn that has a lower adhesion force to the resin coating than the warp and weft yarns that make up the base fabric. Among these, leno yarns whose tenacity per unit denier is 10% or more greater than the warp and weft are preferably used by 20 to 30% or more to substantially prevent the progress of tearing that occurs in the warp and weft. It is intended to be stopped by a large leno thread that is 10% stronger or more, and since the leno thread is longer than the warp and warp threads, and therefore has a greater degree of freedom in change and deformation than the warp threads, it is possible to continuously It can flexibly deal with and absorb tearing forces acting on the sheet. In other words, even if a tearing force acts on the sheet, causing the warp and warp threads to displace and eventually break, the leno threads follow the tearing force, displace and deform without being cut, and eventually absorb the tearing energy and stop tearing. can be done. Next, as a leno yarn, the breaking work is preferably 10% or more, more preferably 20 to 30%, than the warp and warp yarns.
% yarn can be used. The breaking work here is a value approximately expressed by the product of the strength at the time of cutting the yarn and the elongation at the time of cutting. Work at break = Tensile strength at break x Tensile elongation at break For example, polyester filament yarn with a tensile strength at break of 8.0 g per unit denier and a tensile elongation at break of 13% per unit denier is used as the warp and warp threads, and as a leno yarn, the unit 7.0g per denier, tensile elongation at break
18% polyamide fiber yarn is used. At this time, the breaking work of the leno yarn is approximately 21% greater than that of the warp and warp yarns. Furthermore, in consideration of ease of processing, it is desirable to use threads made of the same material. Furthermore, a leno yarn having a breaking elongation that is preferably 5% or more higher than that of the warp and warp yarns can also be used for the braided connection. When polyester filament yarn is used, the breaking elongation of the warp and warp yarns is preferably 15% or less, especially 8 to 12%, while the breaking elongation of the leno yarn is 15% or more, especially 20% or more, and there is no difference between the two. A difference of at least 5% gives good results. If the leno yarn is a synthetic fiber, the degree of polymerization of the polymer material is adjusted at the time of manufacture to maintain a desired strength and a desired high elongation at break, or the filament at the time of manufacture is adjusted. A leno yarn having a desired elongation at break can be obtained by lowering the drawing ratio, for example, an undrawn yarn, or by crimping it during secondary processing. Furthermore, it is also possible to use leno threads that have a smaller adhesion force to the coating resin material than warp and warp threads. In this case, the leno thread may have its surface subjected to silicon processing or the like. In this case, the warp and warp threads are bonded to the coating resin material,
The degree of freedom for displacement and deformation decreases, but the degree of freedom for the leno thread is greater than that for the warp and warp threads, and when tearing force acts on the base fabric, the leno thread slips and is displaced and deformed. Therefore, tearing of the base fabric can be prevented. In order to reduce the adhesive force, the surface of the leno yarn should be subjected to non-adhesive treatment such as silicone treatment or oil treatment, or it should be treated with yarns that are inherently small in adhesive properties, such as polyethylene yarn and polypropylene yarn. You can use As mentioned above, in the base fabric useful in the present invention,
Preferably, the leno yarns for connecting the warp and warp yarns arranged in parallel in the weft and warp directions are substantially longer than the warp and warp yarns, and even if the leno yarns are in a state where the warp and warp yarns are cut or displaced, Constructed with physical properties such as at least a part of it is long enough to not break, is strong, has a large amount of work at break, and/or has a large elongation at break, or has low adhesive strength. The tensile force is maintained at high strength by the warp and warp yarns, and the leno threads resist the impact force at the time of tearing or absorb the tearing energy, and
By leaving the leno threads uncut, delamination between the resin coating and the sheet due to tearing can be prevented. Regarding the special structure fabrics useful in the present invention, further details are provided in Japanese Utility Model Publication No. 52-50234 (1668-1988) and Japanese Patent Publication No. 30381-1981 (30381-1981), which are related to the applicant's earlier applications. 67446), JP-A-55-24415 (JP-A-54-139688), JP-A-55-134242, JP-A-56-159165, JP-A-57-14031, and JP-A-57- The fabrics described in No. 14032 and the like can be suitably used. These textiles typically have a structure as shown in FIG. In the figure, 3 is a warp, 4 is a weft, and 5 is a leno thread. That is, the base fabric used in the present invention is useful for maintaining the mechanical strength of the resulting sheet at a high level. These reinforcing materials may be used for either or both of the conductive sheet portion and the insulating sheet portion, or may be interposed at the boundary between the two. Of course, such a reinforcing material may be composed of not only one layer but also two or more layers. Further, these reinforcing materials may be processed with the above-mentioned matrix and/or conductive material, and may be constructed so as to each have a predetermined specific resistance value. In the flexible sheet according to the present invention, at least one outermost surface area consists of an insulating sheet part (it is particularly preferable that both outer surface layers consist of an insulating sheet part), and the lower layer or middle layer is electrically conductive as a whole. The sheet may be composed of a sheet portion or a layer partially including a conductive sheet portion. The purpose of the conductive sheet part is to shield penetrating radio waves, and for this purpose, the insulating sheet part and the conductive sheet part do not need to be in close contact with each other, or other layers may be interposed therebetween. However, it is more versatile without other layers involved. In particular, in the case of a sheet having insulating sheet portions on both outer surfaces, great effects can be obtained even if the sheet has at least one conductive sheet portion as an intermediate layer. Such a sheet may also, of course, have one or more layers of other materials anywhere within the sheet of the present invention. In addition, as shown in FIG.
The conductive sheet portion 1 can also be provided underneath.
In this case, the sheet has a structure that meets the required performance when the upper and lower surfaces are used, and since the upper and lower surfaces contact each other arbitrarily, problems such as clinging do not occur during handling. In the case of the sheet shown in Figure 1B,
In addition to the above-mentioned effects, the front and back surfaces can be used for different purposes, and if they are constructed with separate layers of other materials, they can be used for applications that partially require different electrical performance. can. Example To show one example of the sheet of the present invention, a special structured fabric was prepared in which 11 1000 denier polyester filaments were used as the warp and weft, and 110 denier nylon filament yarn was used as the leno thread.
This fabric was immersed in a processing liquid containing 40 parts by weight of carbon black (Ketin black) mixed with 100 parts by weight of PVC, and after impregnating it, it was pick-up 100%.
The liquid was squeezed out, then dried, and gelatinized and fixed at 180° C. to form a conductive sheet having a reinforcing material. The thickness of this sheet was approximately 0.48 mm, and the specific resistance value was 10 ⁰ to ^{10 1} Ω·cm. Next, a processing liquid containing 100 parts by weight of PVC, 60 parts by weight of dioctyl phthalate, and a predetermined amount of stabilizers and colorants was applied to each side of this sheet, and dried.
A flexible sheet having insulating sheet portions with a thickness of approximately 0.1 mm on both the front and back surfaces was obtained by gelation heat treatment and fixation. The specific resistance value of this insulating sheet portion was 10 ¹⁶ Ω·cm, and the thickness of the entire flexible sheet was approximately 0.7 mm. When we used this sheet to create a simple box in the laboratory and used a high-frequency sewing machine to perform sewing work inside the box, there was no noise at all on the television screen that was lit just outside. For comparison, when we conducted a similar test using a conventional PVC sheet, it caused disturbances on the TV screen. Tests conducted using conventional PVC sheets with only antistatic treatment also resulted in TV screen disturbances. In addition, when a plain woven fabric with the same basis weight was used as the base fabric, the effect was exactly the same, but the resulting sheet was harder than the sheet of the previous example, and there were some drawbacks in terms of cover fit, etc. It was done. In the production of the flexible sheet of the present invention, any method such as a calendering method, a topping method, a dipping method, a coating method, a laminating method, an extrusion molding method, a spreading method or the like can be used. Effects of the Invention The sheet of the present invention does not cause electromagnetic interference, has no risk of electrical leakage, and exhibits extremely innovative multiple effects. Therefore, this sheet also has the surprising advantage of being suitable for multiple purposes by itself, and is of great industrial value. Furthermore, since this sheet is flexible, it can be used to cover any article in its original shape, and can also be sewn into any shape, making it suitable for a wide variety of products. Enables easy supply. Another great feature is that since the outer surface is insulating, it can be sewn using a high-frequency welder.

[Brief explanation of drawings]

Figures 1A and 2B are cross-sectional views schematically showing an example of the flexible sheet of the present invention, and Figure 3 is an example of a reinforcing base fabric that can be used in the sheet of the present invention. It is a schematic diagram. DESCRIPTION OF SYMBOLS 1... Conductive sheet part, 2... Insulating sheet part, 3... Warp, 4... Weft, 5... Leno thread.

Claims (1)

[Scope of Claims] 1. A sheet-like substrate having at least one layer of an electrically conductive flexible sheet portion, and at least one layer of an electrically insulating flexible sheet portion laminated and bonded to the sheet-like substrate, A flexible sheet for preventing electrical and electromagnetic interference, in which at least one layer of a conductive sheet portion and a conductive sheet portion is reinforced with a fibrous base fabric. 2 The specific resistance value of the conductive sheet portion is 10 ⁸ Ω・
2. The flexible sheet according to claim 1, which has a thickness of 1 cm or less. 3 The specific resistance value of the conductive sheet portion is 10 ⁵ Ω・
3. The flexible sheet according to claim 2, which has a thickness of 1 cm or less. 4 The specific resistance value of the insulating sheet portion is 10 ⁸ Ω・
The flexible sheet according to claim 1, which has a length of cm or more. 5 The specific resistance value of the insulating sheet portion is 10 ¹⁰ Ω・
The flexible sheet according to claim 4, which has a length of cm or more. 6 The specific resistance value of the insulating sheet portion is 10 ¹⁰ ~
The flexible sheet according to claim 5, which has a resistance of 10 ¹⁸ Ω·cm. 7. The flexible sheet according to claim 1, wherein insulating sheet portions are laminated and adhered to both surfaces of each of the at least one conductive sheet portion. 8. The flexible sheet according to claim 1, wherein the insulating sheet portion is made of at least one selected from electrically insulating rubber and synthetic resin. 9. The flexible sheet according to claim 8, wherein the insulating rubber is selected from natural rubber, styrene butadiene rubber (SBR), chlorosulfonated polyethylene rubber, polyurethane rubber, butyl rubber, and isoprene rubber. 10. The flexible sheet according to claim 8, wherein the insulating synthetic resin is selected from polyvinyl chloride (PVC), polyurethane, ethylene-vinyl acetate copolymer, polypropylene, polyethylene, polyacrylonitrile, polyester, and polyamide. . 11. Claim 1, wherein the conductive sheet portion comprises a matrix component made of at least one selected from rubber and synthetic resin, and a conductive substance contained in this matrix component. Flexible sheet as described in section. 12. The flexible sheet according to claim 11, wherein the content of the conductive substance is at least 5% by weight based on the conductive sheet portion. 13 The content of the conductive substance is 10 to 70% by weight
The flexible sheet according to claim 12. 14. The flexible sheet according to claim 11, wherein the conductive material is selected from carbon black, conductive metals, conductive alloys, and conductive metal compounds. 15 The fibrous base fabric has a warp layer consisting of a large number of warps arranged parallel to each other, a weft layer consisting of a large number of wefts arranged parallel to each other so as to be perpendicular to the warps, and the warp and weft. and a leno thread entwined at their intersection.
Flexible sheet as described in section.