Conductive sheet

Abstract

To provide a conductive sheet which is excellent in conductivity, dimensional stability and cushion property, and can suppress dust generation.SOLUTION: A conductive sheet 1 is formed by laminating at least a surface layer 12, an intermediate layer 14, and a back layer 16 in this order. The surface layer 12, the intermediate layer 14, and the back layer 16 are composed of a conductive thermoplastic resin composition. The conductive sheet contains conductive carbon, specific gravity of the intermediate layer 14 is 1.3 to 1.8, and a ratio of thickness of the intermediate layer 14 to the thickness of the whole conductive sheet is 30 to 60%. The conductive sheet 1 does not contain a fibrous material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a conductive sheet. [Background technology]

[0002] It is known that dust has a significant impact on the quality of products in clean rooms where electronic devices, pharmaceuticals, etc. are manufactured. Therefore, it is necessary to minimize dust generation in clean rooms. For example, conductive sheets used on floors, shelves, workbenches, etc. in clean rooms must be highly dust-proof.

[0003] As a conductive sheet intended to suppress dust generation, a conductive sheet has been proposed that uses a fibrous material as a base fabric to ensure dimensional stability and has conductive resin layers on both sides of the base fabric (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-303067 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technique disclosed in Patent Document 1 has a problem in that it is not possible to prevent dust from being generated from the cut surface of the conductive sheet. This dust is generated from the fibrous material of the base fabric.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide a conductive sheet that has excellent conductivity, dimensional stability, and cushioning properties, and is capable of suppressing dust generation. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the "conductive sheet" according to the present invention is characterized by the following (1) to (7). (1) A conductive sheet comprising at least a surface layer, an intermediate layer, and a back layer laminated in this order, the surface layer, the intermediate layer, and the back layer are made of a conductive thermoplastic resin composition, the conductive sheet contains conductive carbon; The specific gravity of the intermediate layer is 1.3 to 1.8, The ratio of the thickness of the intermediate layer to the total thickness of the conductive sheet is 30 to 60%, The hardness of the conductive sheet is 75 to 85, and The conductive sheet is a conductive sheet that does not contain fibrous materials. (2) In the conductive sheet described in (1) above, The conductive thermoplastic resin composition has a vinyl chloride resin matrix. (3) In the conductive sheet according to (1) or (2), The surface resistance between two points measured in accordance with NFPA99 is 2.5 x 10 4 Ω~1.0×10 7 Being Omega. (4) In the conductive sheet according to any one of (1) to (3), The resistance between the top and bottom measured in accordance with NFPA99 is 2.5 x 10 4 Ω~1.0×10 7 Being Omega. (5) In the conductive sheet according to any one of (1) to (4), The amount of dust particles with a particle size of 0.5 μm or more according to JIS B9923 (tumbling method) was 100 particles / ft per two 300 mm x 300 mm test pieces of the conductive sheet. 3 It must be less than or equal to: (6) In the conductive sheet according to any one of (1) to (5), The rate of change in length due to heating measured in accordance with JIS A1454 is 2.0% or less. (7) In the conductive sheet according to any one of (1) to (6), The amount of dent measured in accordance with JIS A1454 must be 0.3 mm or more at 23°C and 1.5 mm or less at 45°C.

[0008] According to the conductive sheet having the configuration (1) above, a surface layer, an intermediate layer, and a back layer are laminated in this order, and the surface layer, the intermediate layer, and the back layer are made of a conductive thermoplastic resin composition, and the conductive sheet contains conductive carbon, and the specific gravity and thickness of the intermediate layer and the hardness of the conductive sheet are set within specific ranges, and the conductive sheet does not contain any fibrous material, so that a conductive sheet can be provided that is excellent in conductivity, dimensional stability, and cushioning properties and can suppress dust generation.

[0009] According to the conductive sheet having the above configuration (2), since the conductive thermoplastic resin composition has a vinyl chloride resin as a matrix, it is possible to provide a conductive sheet that can further improve dimensional stability and cushioning properties and further suppress dust generation.

[0010] According to the conductive sheet having the above configuration (3), the surface resistance between two points measured in accordance with NFPA99 is within a specific range, so that a conductive sheet having excellent conductivity can be provided.

[0011] According to the conductive sheet having the above configuration (4), the resistance between the top and bottom measured in accordance with NFPA99 is within a specific range, so that a conductive sheet having excellent conductivity can be provided.

[0012] According to the conductive sheet having the configuration of (5) above, the amount of dust particles having a particle size of 0.5 μm or more according to JIS B9923 (tumbling method) per two test pieces of the conductive sheet measuring 300 mm × 300 mm is 100 particles / ft 3 Since the thickness is less than 100 μm, it is possible to provide a conductive sheet that can further suppress dust generation.

[0013] According to the conductive sheet having the above configuration (6), the rate of length change due to heating measured in accordance with JIS A1454 is 2.0% or less, so that a conductive sheet with even better dimensional stability can be provided.

[0014] According to the conductive sheet having the configuration (7) above, the amount of depression measured in accordance with JIS A1454 is 0.3 mm or more at 23°C and 1.5 mm or less at 45°C, so that a conductive sheet with even better cushioning properties can be provided. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a conductive sheet that is excellent in conductivity, dimensional stability, and cushioning properties, and that can suppress dust generation.

[0016] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view of a conductive sheet according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the conductive sheet according to this embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the conductive sheet according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of a conductive sheet according to the present invention will be described with reference to the drawings.

[0019] The conductive sheet 1 according to this embodiment is formed by laminating a surface layer 12, an intermediate layer 14, and a back layer 16. The conductive sheet 1 according to this embodiment also contains conductive carbon. The conductive carbon may be contained as the conductive carbon layer 13, or may be contained in any of the layers (conductive thermoplastic resin composition) of the surface layer 12, the intermediate layer 14, and the back layer 16. That is, as shown in FIGS. 1 and 2, the conductive sheet 1 according to this embodiment may be formed by laminating the surface layer 12, the conductive carbon layer 13, the intermediate layer 14, and the back layer 16. Alternatively, as shown in FIG. 3, the conductive sheet 1 may be formed by laminating the surface layer 12, the intermediate layer 14, and the back layer 16, and the conductive carbon may be contained in any of the layers (for example, the back layer). Note that, although the following description will mainly focus on an embodiment in which conductive carbon is contained as the conductive carbon layer 13, the conductive sheet according to this embodiment is not limited to this embodiment.

[0020] The characteristics of each layer are described below. The surface layer 12 is a layer located on the surface of the sheet and has abrasion resistance, scratch resistance, and contamination resistance. Here, the layer located on the surface of the sheet means the layer located on the top when the conductive sheet is installed. The conductive carbon layer 13 is located between the surface layer and the back layer, and is a layer that enhances the conductivity of the sheet, and contains conductive carbon. The intermediate layer 14 is located between the surface layer and the back layer, and is a layer that contributes to the physical properties (cushioning properties, dimensional stability) of the entire sheet. The back layer 16 is the layer located at the bottom of the sheet and prevents the sheet from warping toward the surface layer. To enhance conductivity, it may contain conductive carbon. Here, the layer located at the bottom of the sheet means the layer located at the bottom when the conductive sheet is installed.

[0021] The surface layer 12, the conductive carbon layer 13, the intermediate layer 14 and the back layer 16 are made of a conductive thermoplastic resin composition. Examples of conductive thermoplastic resin compositions include those in which a conductive material is mixed with a matrix such as vinyl chloride resin, polyester, polyamide, polyolefin, acrylic resin, epoxy resin, phenolic resin, etc. Examples of conductive materials include metal powder, carbon powder, graphite powder, and ferrite powder.

[0022] Among these, vinyl chloride resin is preferred as the matrix of the conductive thermoplastic resin composition from the viewpoints of excellent dimensional stability and cushioning properties and suppressing dust generation. Furthermore, it is even more preferred that the surface layer 12, conductive carbon layer 13, intermediate layer 14, and back layer 16 are all made of a conductive thermoplastic resin composition having a vinyl chloride resin matrix (hereinafter also referred to as a conductive vinyl chloride resin composition). Hereinafter, an example will be described in which the surface layer 12, conductive carbon layer 13, intermediate layer 14, and back layer 16 are all sheets made of a conductive vinyl chloride resin composition, but the present invention is not limited to this embodiment.

[0023] First, the conductive vinyl chloride resin composition used to prepare the sheet of the intermediate layer 14 will be described. The vinyl chloride resin used in the conductive vinyl chloride resin composition is not particularly limited, but examples thereof include a homopolymer of vinyl chloride, a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer, and a graft copolymer in which a polymer other than a polyvinyl chloride resin is graft-copolymerized with a vinyl chloride monomer. The polyvinyl chloride resins may be used alone or in combination of two or more.

[0024] Examples of other monomers copolymerizable with the vinyl chloride monomer include α-olefins such as ethylene, propylene, and butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl acrylate; aromatic vinyls such as styrene and α-methylstyrene; and N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide. One type of the other monomers may be used alone, or two or more types may be used in combination.

[0025] The average degree of polymerization of the vinyl chloride resin according to JIS K6720-2 is preferably 800 to 2,500, more preferably 1,000 to 2,000.

[0026] Furthermore, examples of plasticizers used in vinyl chloride resins include high molecular weight plasticizers such as phthalate esters {e.g., dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), etc.}, trimellitate esters {e.g., trioctyl trimellitate (TOTM), tri-normal-octyl trimellitate (TnOTM)}, adipate esters {e.g., diisobutyl adipate (DIBA), diisodecyl adipate (DIDA)}, phosphates {e.g., triethyl phosphate, tricresyl phosphate}, and epoxy polyesters {e.g., epoxidized soybean oil}.

[0027] Examples of conductive materials that impart conductivity to vinyl chloride resins include metal powder, carbon powder, graphite powder, ferrite powder, conductive plasticizers, and antistatic agents. Examples of metal powders include powders of silver, nickel, copper, gold, aluminum, iron, graphite, and the like. Examples of carbon powder include carbon black. Examples of the conductive plasticizer include phthalate ester-based conductive plasticizers and adipic acid ester-based conductive plasticizers. Examples of antistatic agents include anionic antistatic agents (e.g., alkyl sulfate type, alkyl aryl sulfate type, alkyl phosphate type, alkylamine sulfate type, etc.), cationic antistatic agents (e.g., quaternary ammonium salt type, quaternary ammonium resin type, imidazoline type, etc.), nonionic agents (e.g., sorbitan type, ether type, amine and amide type, ethanolamide type, etc.), betaines, etc.

[0028] The amount of the conductive material to be mixed is preferably 10 to 50 parts by mass, and more preferably 20 to 45 parts by mass, per 100 parts by mass of the vinyl chloride resin.

[0029] Furthermore, the vinyl chloride resin composition may further contain known inorganic fine particles (calcium carbonate, calcined clay, talc, silica, etc.), stabilizers, lubricants, flame retardants, crosslinking agents, processing aids, colorants, etc., as needed. The amounts of these additives may also be arbitrary as long as they do not impair the effects of the present invention.

[0030] The vinyl chloride resin composition can be easily prepared by kneading the various materials described above using a known kneader.

[0031] The intermediate layer 14 can be formed by applying a conventionally known method such as extrusion molding, injection molding, calendar molding, or press molding.

[0032] Next, the conductive vinyl chloride resin composition used to prepare the sheets of the surface layer 12 and the back layer 16 will be described. The conductive vinyl chloride resin composition used to prepare the sheet for the surface layer 12 is the same as the conductive vinyl chloride resin composition used to prepare the sheet for the intermediate layer 14, but to improve abrasion resistance, it preferably contains a smaller amount of filler than the intermediate layer 14. Also, to improve conductivity, it preferably contains a larger amount of conductive plasticizer than the intermediate layer 14. The composition preparation method and molding method are the same as those for the intermediate layer 14. The conductive vinyl chloride resin composition used to prepare the sheet for the back layer 16 is the same as the conductive vinyl chloride resin composition used to prepare the sheet for the intermediate layer 14, but to increase flexibility, it preferably contains a larger amount of plasticizer than the intermediate layer 14. The composition preparation method and molding method are the same as those for the intermediate layer 14. The conductive vinyl chloride resin composition used to prepare the sheet for the conductive carbon layer 13 is similar to the conductive vinyl chloride resin composition used to prepare the sheet for the intermediate layer 14, but differs in that it contains conductive carbon to enhance conductivity. The composition preparation method and molding method are similar to those for the intermediate layer 14.

[0033] Preferred types of conductive carbon include carbon black, graphite, carbon fiber, etc. The proportion of the conductive carbon contained in the conductive carbon layer 13 is more preferably 10 to 30 mass %.

[0034] The thickness of the intermediate layer 14 is preferably 0.6 mm to 1.2 mm, and more preferably 0.8 mm to 1.0 mm. The thickness of the surface layer 12 is preferably 0.2 mm to 0.5 mm, and more preferably 0.3 mm to 0.4 mm. The thickness of the back layer 16 is preferably 0.3 mm to 1.0 mm, and more preferably 0.5 mm to 0.8 mm. The thickness of the conductive carbon layer 13 is preferably 0.1 mm to 0.4 mm, and more preferably 0.2 mm to 0.3 mm.

[0035] In the present invention, the ratio of the thickness of the intermediate layer 14 to the thickness of the entire conductive sheet must be 30 to 60%. The specific gravity of the intermediate layer 14 must be 1.3 to 1.8. By setting the thickness ratio and specific gravity of the intermediate layer within the specific ranges as described above, it becomes possible to improve dimensional stability without using a base fabric made of a fibrous material.

[0036] The thickness ratio of the intermediate layer 14 is more preferably 40 to 50%. The specific gravity of the intermediate layer 14 is more preferably 1.5 to 1.7. The specific gravity is measured based on JIS K7112.

[0037] As described above, the conductive sheet 1 according to this embodiment may be formed by laminating a surface layer 12, a conductive carbon layer 13, an intermediate layer 14, and a back layer 16, as shown in Figures 1 and 2. Alternatively, the conductive sheet 1 may be formed by laminating a surface layer 12, an intermediate layer 14, and a back layer 16 containing conductive carbon, as shown in Figure 3. There are no particular limitations on the lamination method, and examples include a method in which each layer is calender-molded and then laminated.

[0038] The overall thickness of the conductive sheet 1 of the present invention is preferably 1.0 mm to 2.5 mm, and more preferably 1.5 mm to 2.0 mm.

[0039] Furthermore, the conductive sheet 1 of the present invention has a hardness measured in accordance with JIS K7215 of 75 to 85. When the specific gravity of the intermediate layer 14 increases, the cushioning properties tend to be lost, but by setting the hardness of the conductive sheet 1 to 75 to 85, the dimensional stability can be improved without deteriorating the cushioning properties. The hardness is more preferably 78 to 82.

[0040] In a preferred embodiment of the present invention, the conductive sheet 1 of the present invention has a two-point surface resistance measured in accordance with NFPA (National Fire Protection Association) 99 of 2.5×10 4 Ω~1.0×10 7 Ω, preferably 1.0×10 5 Ω~1.0×10 6 In this embodiment, a conductive sheet having excellent conductivity can be provided.

[0041] In a preferred embodiment of the present invention, the conductive sheet 1 of the present invention has a resistance between the top and bottom measured in accordance with NFPA99 of 2.5×10 4Ω~1.0×10 7 Ω, preferably 1.0×10 5 Ω~1.0×10 6 In this embodiment, a conductive sheet having excellent conductivity can be provided.

[0042] In a preferred embodiment of the present invention, the conductive sheet 1 of the present invention has a particle size of 100 particles / ft 3 per two test pieces of 300 mm×300 mm according to JIS B9923 (tumbling method). 3 Not more than 50 pieces / ft 3 It is more preferable that the following is satisfied: In this embodiment, a conductive sheet that further suppresses dust generation can be provided.

[0043] In a preferred embodiment of the present invention, the conductive sheet 1 of the present invention has a length change rate due to heating of 2.0% or less, more preferably 1.5% or less, as measured in accordance with JIS A1454. In this embodiment, a conductive sheet with further improved dimensional stability can be provided.

[0044] In a preferred embodiment of the present invention, the conductive sheet 1 of the present invention has a depression amount measured in accordance with JIS A1454 of preferably 0.3 mm or more, more preferably 0.5 mm or more, at 23° C. Furthermore, the depression amount measured in accordance with JIS A1454 is preferably 1.5 mm or less, more preferably 1.0 mm or less, at 45° C. In this embodiment, a conductive sheet with even improved cushioning properties can be provided.

[0045] The specific gravity of the intermediate layer 14 can be adjusted by adjusting the amount of filler, and the hardness of the conductive sheet 1 can be adjusted by adjusting the amount of plasticizer.

[0046] Another feature of the conductive sheet 1 of the present invention is that it does not contain any fibrous materials. Therefore, there is absolutely no dust generation due to the presence of fibrous materials. Note that fibrous materials refer to all fibers commonly used as the base fabric of conductive sheets used in flooring materials, etc., and include well-known synthetic fibers, semi-synthetic fibers, natural fibers, etc.

[0047] The conductive sheet 1 of the present invention is particularly suitable for use as flooring, shelves, workbenches, etc. in clean rooms. [Example]

[0048] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0049] Examples 1 to 8 In Examples 1 to 8, the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the conductive carbon layer, the vinyl chloride resin composition for the intermediate layer, and the vinyl chloride resin composition for the back layer of Examples 1 to 8 were prepared by kneading the components in the amounts shown in Table 1 below using a kneader.

[0050] [Table 1]

[0051] The various materials shown in Table 1 are as follows: PVC (vinyl chloride resin): S1001, S1003 (manufactured by Kaneka Corporation, average polymerization degree based on JIS K6720-2 = 1030, 1300) Plasticizer: Diisononyl phthalate (DINP) (manufactured by J-Plus Co., Ltd.) Conductive plasticizer: C-1000 (manufactured by New Japan Chemical Co., Ltd.) Antistatic agent: LV-70 (ADEKA Corporation) Stabilizer: NPS-500 (ADEKA Corporation) Calcium carbonate: Escalon #1500 (manufactured by Sankyo Seifun Co., Ltd.) Conductive carbon: EC600JD (manufactured by Lion Specialty Chemicals) For PVC, S1003 was used for the surface layer and S1001 for the other layers.

[0052] Next, each composition was calendered to form the surface layer 12, conductive carbon layer, intermediate layer 14 and back layer 16 in this order, to produce conductive sheets having the thicknesses shown in Table 2 below.

[0053] The various conductive sheets thus produced were measured for the following physical properties. Specific gravity of middle layer 14 (measured in accordance with JIS K7112) Conductive sheet hardness (measured in accordance with JIS K7215) - Length change rate of conductive sheet due to heating (measured in accordance with JIS A1454) - Surface resistance between two points on a conductive sheet (measured in accordance with NFPA99) Resistance between the top and bottom of the conductive sheet (measured in accordance with NFPA99) Dust generation amount of conductive sheet (measured in accordance with JIS B9923 (tumbling method)) - Conductive sheet dent amount (measured in accordance with JIS A1454)

[0054] The results are shown in Table 2 below.

[0055] [Table 2]

[0056] From the results of each example, it was found that the conductive sheet of the example is formed by laminating a surface layer 12, an intermediate layer 14, and a back layer 16 in this order, the surface layer 12, the intermediate layer 14, and the back layer 16 are made of a conductive thermoplastic resin composition, the conductive sheet contains conductive carbon, the specific gravity of the intermediate layer 14 is 1.3 to 1.8, the ratio of the thickness of the intermediate layer 14 to the thickness of the entire conductive sheet is 30 to 60%, the hardness of the conductive sheet is 75 to 85, and the conductive sheet 1 does not contain a fibrous material, and is excellent in conductivity, dimensional stability, and cushioning, and can suppress dust generation.

[0057] Comparative Examples 1 to 25 Examples 1 to 8 above were repeated, except that conductive sheets having the thicknesses and physical properties shown in Tables 3 to 5 below were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 1 as the base, Comparative Examples 1, 9 and 17 were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 2 as the base, Comparative Examples 2, 10 and 18 were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 3 as the base, Comparative Examples 3, 11 and 19 were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 4 as the base, Comparative Examples 4, 12 and 20 were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 5 as the base, Comparative Examples 5, 13 and 21 were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 6 as the base, Comparative Examples 6, 14 and 22 were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 7 as the base, Comparative Examples 7, 15 and 23 were produced. Using the vinyl chloride resin composition for the surface layer, the vinyl chloride resin composition for the intermediate layer and the vinyl chloride resin composition for the back layer in Example 8 as the base, Comparative Examples 8, 16, 24 and 25 were produced. The results are shown in Tables 3 to 5.

[0058] [Table 3]

[0059] [Table 4]

[0060] [Table 5]

[0061] In Comparative Examples 1 to 4, the specific gravity of the intermediate layer 14 was 1.2, which was below the lower limit defined in the present invention, and therefore the rate of length change due to heating was deteriorated. In Comparative Examples 5 to 8, the specific gravity of the intermediate layer 14 was 1.84, which exceeded the upper limit specified in the present invention, and therefore the conductivity was deteriorated. In Comparative Examples 9 to 16, the ratio of the thickness of the intermediate layer 14 to the thickness of the entire conductive sheet was outside the range specified by the present invention, and therefore the length change rate or conductivity due to heating deteriorated. In Comparative Examples 17 to 24, the hardness of the conductive sheets was outside the range specified in the present invention, and therefore the length change rate and / or the dent rate due to heating was deteriorated. The conductive sheet of Comparative Example 25 was made by bonding a base fabric made of polyester and rayon to the back layer 16 side of the conductive sheet of Example 8, and since it contained fibrous materials, it generated a significant amount of dust.

[0062] It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. are possible as appropriate. In addition, the material, shape, dimensions, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as the present invention can be achieved.

[0063] Here, the features of the above-described embodiments of the conductive sheet according to the present invention will be briefly summarized and listed below in (1) to (7). (1) A conductive sheet (1) comprising at least a surface layer (12), an intermediate layer (14), and a back layer (16) laminated in this order, The surface layer (12), the intermediate layer (14), and the back layer (16) are made of a conductive thermoplastic resin composition, the conductive sheet contains conductive carbon, The specific gravity of the intermediate layer (14) is 1.3 to 1.8, the ratio of the thickness of the intermediate layer (14) to the total thickness of the conductive sheet is 30 to 60%, The hardness of the conductive sheet (1) is 75 to 85, and The conductive sheet (1) does not contain fibrous materials. Conductive sheet. (2) In the conductive sheet of (1), The conductive sheet, wherein the conductive thermoplastic resin composition has a conductive vinyl chloride resin as a matrix. (3) In the conductive sheet of (1) or (2), The surface resistance between two points measured in accordance with NFPA99 is 2.5 x 10 4 Ω~1.0×10 7 Ω, conductive sheet. (4) In any one of the conductive sheets (1) to (3), The resistance between the top and bottom measured in accordance with NFPA99 is 2.5 x 10 4 Ω~1.0×10 7 Ω, conductive sheet. (5) In any one of the conductive sheets (1) to (4), The amount of dust particles with a particle size of 0.5 μm or more according to JIS B9923 (tumbling method) was 100 particles / ft per two 300 mm x 300 mm test pieces of the conductive sheet. 3 Below is a conductive sheet. (6) In any one of the conductive sheets (1) to (5), A conductive sheet whose rate of length change due to heating, measured in accordance with JIS A1454, is 2.0% or less. (7) In any one of the conductive sheets (1) to (6), A conductive sheet whose depression measured in accordance with JIS A1454 is 0.3 mm or more at 23°C and 1.5 mm or less at 45°C. [Explanation of symbols]

[0064] 1 Conductive sheet 12 Surface layer 13 Conductive carbon layer 14 Middle Class

Claims

1. A conductive sheet comprising at least a surface layer, an intermediate layer, and a back layer laminated in this order, the surface layer, the intermediate layer, and the back layer are made of a conductive thermoplastic resin composition, the conductive sheet contains conductive carbon; The specific gravity of the intermediate layer is 1.3 to 1.8, The ratio of the thickness of the intermediate layer to the total thickness of the conductive sheet is 30 to 60%; The hardness of the conductive sheet is 75 to 85, and The conductive sheet does not contain fibrous materials. Conductive sheet.

2. The conductive sheet according to claim 1 , wherein the conductive thermoplastic resin composition has a vinyl chloride resin matrix.

3. The surface resistance between two points measured in accordance with NFPA99 is 2.5 x 10 ４ Ω ~ 1.0 x 10 ７ The conductive sheet according to claim 1 or 2, wherein the resistance is Ω.

4. The resistance between the top and bottom measured in accordance with NFPA99 is 2.5 x 10 ４ Ω ~ 1.0 x 10 ７ The conductive sheet according to any one of claims 1 to 3, wherein the resistance is Ω.

5. The amount of dust particles with a particle size of 0.5 μm or more according to JIS B9923 (tumbling method) per two test pieces of the conductive sheet, each measuring 300 mm x 300 mm, is 100 particles / ft. ３ The conductive sheet according to any one of claims 1 to 4, wherein:

6. 6. The conductive sheet according to claim 1, wherein the rate of change in length due to heating measured in accordance with JIS A1454 is 2.0% or less.

7. 7. The conductive sheet according to claim 1, wherein the amount of depression measured in accordance with JIS A1454 is 0.3 mm or more at 23°C and 1.5 mm or less at 45°C.

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