JPH03149465A - Material for rubber coated gasket - Google Patents

Abstract

PURPOSE:To increase continuity characteristic of a material by forming a rubber that is a primary component of a rubber layer out of conductive carbon black, graphite, and of nitrile rubber including radical acceptor, and by bonding the rubber layer and a metallic plate through a primer layer. CONSTITUTION:A cold rolling plate, stainless steel plate, or aluminium plate and so on is used as a substrate metallic plate 1. The metallic plate 1 is degreased and cleaned, and after the surface is roughened by, for example, sand blast method, a photophate film, a chromate film, and so on, is formed so as to form a chemical conversion coated layer 2. A primer primarily comprising phenol aldehyde resin and nitrile rubber compound, is applied thereto, so as to form a primer layer 3, on which conductive carbon black, graphite, and a nitrile rubber including radical acceptor are applied, so as to form a rubber layer 4. A dispersion liquid of graphite and the like is applied thereto and dried in order to present baking, and to give non-viscosity, so as to form a non-viscous layer 5. The material of high continuity can be obtained thereby.

Description

[Detailed description of the invention]

[Industrial Field] The present invention relates to gasket materials, and particularly to improvements in rubber-coated gasket materials formed by forming a rubber layer on a thin metal plate. [Conventional technology] Conventionally, this type of rubber-coated gas kettle material was
Generally, a rubber layer coating is formed on the surface of a thin base metal plate such as a cold-rolled steel plate, stainless steel plate, or aluminum plate, and this sheet-like material is punched into any shape and used for various equipment and machines. etc. are used as gaskets. Since the base material of this rubber-coated gasket is a metal plate, there is no blow-through of the gasket due to internal pressure.
Additionally, the rubber layer conforms to the irregularities on the flange surface, providing excellent sealing performance. Next, a typical structure of the rubber-coated gasket material and its manufacturing method will be specifically explained with reference to the drawings according to the present invention. First, the surface of the base metal plate 1 is degreased, then the surface is roughened by shot blasting, scotch blasting, etc., and the chemical conversion treatment layer 2 is formed.The adhesive layer is made of phenol resin and nitrile rubber, and carbon for reinforcing filling is applied to the surface. Then, a primer mainly composed of rubber containing a vulcanizing agent and additives is applied to form a primer layer 3. A rubber solution prepared by dissolving nitrile rubber with excellent oil resistance, reinforcing filler carbon, a vulcanizing agent, and additives in an organic solvent is then applied onto the primer layer 3, dried and vulcanized to form a rubber solution. This is a struggle to form layer 4. Also. Depending on the gasket usage conditions, a non-adhesive layer 5 is formed by further coating graphite, molybdenum disulfide, etc. on the rubber layer 4. [Problems to be Solved by the Invention] However, in the conventional rubber-coated gasket material as described above, since nitrile rubber is used as the polymer of the rubber layer 4, oil resistance and oil resistance as a sealing function are insufficient. Although it has excellent chemical properties, it contains reinforcing carbon, which is different from conductive carbon black, so the electrical conductivity of the rubber layer 4 is significantly inferior. Therefore, in such rubber-coated gasket materials, the sealing part is electrically insulated. For example, it is impossible to perform electric welding by passing a current through the seal, and when used as a gasket in an electromagnetic shielding material, problems arise such as the seal becoming a defective part. Therefore, it is possible to mix conductive carbon as the reinforcing filler carbon, but when it is mixed, the viscosity of the rubber solution obtained by dissolving the compound in an organic solvent becomes extremely high, and the carbon gel (insoluble This causes problems such as the formation of a rubber layer coating, making it difficult to form a rubber layer coating. [Object of the Invention] The present invention was made in order to eliminate the drawbacks of the conventional rubber-coated gasket materials described above, and provides a rubber-coated gasket that has sufficient electrical conductivity in addition to the sealing properties unique to rubber. Its main purpose is to provide materials for use. [Means for Solving Problem 11] The present inventors conducted various studies regarding the above problems, and found that the rubber layer formed on the surface of a metal plate. Use conductive carbon black, graphite and nitrile rubber containing radical acceptors? Alternatively, by using the above-mentioned rubber as the main component rubber used in the rubber layer and the primer layer, in addition to oil resistance and chemical resistance as a sealing function, the material is generally referred to as an electrically conductive material because of its electrical conductivity. 101Ω・1 or less preferably 1000・
It was discovered that a rubber-coated gasket material having a volume resistivity of 1 or less could be obtained, and the present invention was completed based on this finding. That is, the present invention provides a gasket material in which a rubber layer is formed on one or both sides of a metal plate, in which the main component of the rubber layer, the rubber layer, and the primer layer is conductive carbon black, graphite, and a radical acceptor. It is characterized by being made of nitrile rubber containing. [Function] In the rubber-coated gasket material having the above structure, a nitrile rubber layer containing conductive carbon black, graphite, and a radical acceptor is formed, so high conductivity can be obtained due to the synergistic effect of the three components. . [Specific Examples of the Invention] The present invention will be described in detail below based on the drawings. In the drawings, as the base metal plate 1, a cold rolled plate, a stainless steel plate, an aluminum plate, etc. are used, and the thickness varies depending on the required characteristics, but in general, a thickness of 0.1 to 1.6 mm is used. . The base metal plate 1 is first degreased and cleaned. The cleaning method is the generally known solvent degreasing method. An alkaline degreasing method, an electrolytic degreasing method, an ultrasonic cleaning method, a steam cleaning method, etc. may be used. Next, methods for roughening the surface of the metal plate include sandblasting, shotplast, gritblast, and scotchblast. Further, the surface of the metal plate is subjected to a chemical conversion treatment to form a chemical conversion treatment layer 2. The chemical conversion treatment method varies depending on the type of steel sheet, and in the case of cold rolled steel sheet, phosphate coating is used. In the case of aluminum plates, it is preferable to form a chromate coating, whereas in the case of stainless steel plates, they are chemically inert and difficult to bond compared to metal plates, and generally require oxalate coating or treatment. A method of plating with a metal that is easy to bond, such as zinc or copper, is used. Next, a primer is applied to form a primer layer 3. The primer mainly contains a phenolic resin and a nitrile rubber compound, and is adjusted to a solid content concentration of 10 to 25% by weight with a ketone solvent such as methyl ethyl ketone, methyl isobutyl ketone, or diisobutyl ketone. The solvent may be a mixed solvent with an alcoholic solvent such as methanol or ethanol.The reason why a nitrile rubber compound is added to the primer is to give it flexibility suitable for drawing processing. The blending ratio of and nitrile rubber compound is 8:2 to 4:6.
．． Preferably, the ratio is 6:4. In the present invention, there are two formulations using carbon black other than conductive carbon black or conductive carbon black as the rubber compound for the primer, and these are as follows. Contains rubber compound! Nitrile rubber (NBR) 100PH
R Zinc white 3-10 Stearic acid 0.3-1.5 Carbon black (NY, PET carbon, etc.) 40-200
Coumarone indene resin 20~60 Anti-aging agent 1~7 Sulfur
0.5-4 Vulcanization accelerator 1-7 Rubber compound combination■ Nitrile rubber (NBR) 100PH
R Zinc white 3-10 Stearic acid 0.3-1.5 Conductive carbon black 10-150 Graphite 50-200 Radical acceptor 0.5-5 Anti-aging agent
1-10 sulfur
0.5-4 vulcanization accelerator
When formulations 1 to 7 (3) are used, the primer layer is composed of a phenolic resin and a rubber compound with low conductivity, and is therefore an electrical insulator itself. Therefore, the area between points A and B in the drawing should be non-conductive, but because the primer layer is thin, a tunnel effect tends to occur, and when coating the rubber layer 4, which will be described later, the primer rubber melts and the rubber It is considered that the conductivity between points A and B is high because of mixing with the rubber of layer 4, etc. Next, when formulation (2) is used, since the primer layer contains a highly conductive rubber compound, the conductivity at point A-H is greater than that of formulation (2). In addition, for the polymer of the rubber compound used in the primer, carboxyl group-containing nitrile rubber, chlorinated rubber, etc. may be used instead of nitrile rubber.For the phenolic resin, novolac type or cresol type pure phenol resin may be used. else. resol modification, cashew modification, alkylbenzene modification,
Modified phenolic resins such as furan-modified and polyvinyl butyral-modified resins may also be used. The thickness of the primer layer is 2 to 20 μm, preferably 2 to 1
It is set to 0 μm. If the thickness of the primer layer is less than 2 μm, the formation of the layer will be insufficient, and if it exceeds 20 μm, the conductivity will be low. Next, a rubber liquid of nitrile rubber containing conductive carbon black, graphite and a radical acceptor is applied onto the primer layer, dried and vulcanized to a thickness of 10 to 30 mm on one side.
A rubber layer 4 with a thickness of 0 μm is formed. The conductive carbon black used in the present invention has a more developed structure (chain structure of carbon black particles) than other carbon blacks, has a small particle size, has a large surface area, and has the ability to capture electrons. It has characteristics such as low impurities and well-developed graphitization (crystallization).Specifically, acetylene black. Ketjen black, SAF carbon (superab
(former name of the N-Zoo series of carbon separation methods by ASTM), etc., with an average particle size of 50 μm or less and D. B. P (dibutyl phthalate) absorption amount 100 kg3”/100
g and an iodine absorption amount of Song/g or more. These carbon blacks are included in the rubber compound.
By blending 0 to 150 PHR, preferably 20 to 100 PHR, a rubber having high conductivity can be obtained. High conductivity cannot be obtained below IOPHR, and above 150 PHR. Problems arise such as poor dispersion into the rubber compound and generation of a large amount of carbon gel (insoluble matter). Since the viscosity of the rubber compound when dissolved in a solvent at 25 to 40% by weight is extremely high, graphite is used as a filler for the purpose of increasing the weight by 50 to 200 PHR, preferably 80 PHR.
By blending up to 130 PHR, it is possible to suppress the generation of carbon gel and lower the viscosity while maintaining conductivity. This graphite has little effect in reducing viscosity below 50 PHR, and below 200 PHR.
Above this amount, it becomes difficult to disperse it into the rubber compound. Also. Graphite preferably has a particle size of 50 μm or less.In addition, metal powder, specifically aluminum powder, nickel powder, silver powder, etc., and inorganic fillers commonly used in rubber, specifically carbon black other than conductive carbon black, silicic acid Salts, clay, talc, etc. may be blended with graphite, but if metal powder or inorganic fillers commonly used in rubber are used alone, the former may This has a great negative effect on the general physical properties of the rubber compound, and the latter has a negative effect on the electrical conductivity. In addition, in the rubber compound obtained through the above process, carbon gel (insoluble matter) is generated in the rubber mixture. Complete dissolution in solvents is difficult. The mechanism of the generation of insoluble matter is that radicals generated when rubber molecules are cut during rubber crosslinking combine with carbon black to form a three-dimensional network structure. Therefore, a radical acceptor with a PER of 0.5 to 5 is added to prevent this by capturing the radicals of the rubber molecules before they combine with carbon black. If the radical acceptor is less than 0.5 PHR, the effect of preventing carbon gel formation is small, and even if it is added in an amount greater than 5 PHR, the effect is not significantly increased. Specifically, the radical receptor is α,α-diphenyl-β
- Picrylhydrazyl, N, N, N. N'-tetraethyl-p-phenylenediamine. Free radicals from N-(3-N-oxyanilino-1,3-dimethylbutylidene)aniline oxide, PeP-difluorodiphenylamino, aryalanyl, iodine, iron(m) chloride (FeCjla), and the like. The rubber compound obtained here is the above-mentioned rubber compound (2), which is mixed with an aromatic or hydrocarbon solvent such as toluene. Dissolve ester solvents such as propyl acetate and butyl acetate, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and alcohol solvents such as ethanol and methanol alone or in a mixture to reduce the viscosity to 2000~
Adjust the coating to 30,000 CP and apply with a knife coater. The coating thickness is 10 to 300 μm on one side as described above.
shall be. If it is less than 10 μm, it will not fit well with the flange surface,
Moreover, when the diameter is larger than 300 μm, the heat resistance as a gasket decreases. According to the present invention, by using nitrile rubber containing conductive carbon black, graphite, and a radical acceptor as the main component rubber of the rubber layer or the rubber layer and the primer layer, it has high conductivity and can be easily coated with a knife coater. It is possible to obtain a rubber-coated gasket material that is easy to apply by means of a rubber coating, etc., and has a beautiful surface condition. If each of the above three components is used alone or in a combination of less than two components, the conductivity will decrease, the viscosity of the rubber solution will be high, and a large amount of carbon gel will be generated when the rubber solution is used. A problem occurs. In other words, the gasket material of the present invention can be obtained by the synergistic effect of the three components: conductive force, carbon black, graphite, and radical acceptor. Further, a dispersion of graphite or molybdenum disulfide or the like is applied to the rubber surface for the purpose of preventing seizing and imparting non-adhesive properties and is dried to form a non-adhesive layer 5. In this non-adhesive layer, a polymer material capable of forming a film such as paraffin wax, acrylic resin, or phenol resin can be used as a binder for the purpose of fixing particles such as graphite. This non-adhesive layer 5 is not necessarily necessary, and if adhesion with other materials is required, it is better not to have it. Therefore, the presence or absence of the non-adhesive layer 5 is used depending on the conditions of use. Example

[1] After performing alkaline degreasing on the surface of a cold-rolled steel plate with a thickness of 0.251, the surface is roughened by polishing by Scotch blasting. Next, a phosphate-based chemical conversion treatment is performed to form a rust-preventing film of iron phosphate. Next, a primer is applied to both sides of the steel plate using a reverse control coater, and heat treated in a 150C oven for 90 seconds (130 to 180C, preferably 1 to 10 minutes) to form a primer layer with a thickness of 5μm on one side. The composition of the primer is shown below. Rubber compound formulation for primer ■ Nitrirugo A (NBR) 100PHR zinc white 5 Stearic acid 0.5MT carbon
150 coumaron indene resin
40 Anti-aging agent 5 Sulfur 1.2 Vulcanization accelerator
2.4 Primer Blend I Blend ■Rubber 6% by weight Phenol resin 9 Methyl ethyl ketone 76.5 Methyl isobutyl ketone 8.5 Next, a rubber liquid having the following composition was coated on the primer layer obtained above using a knife coater. After drying at 70°C for 30 minutes (60-130°C for 10 minutes or more is better) to volatilize the solvent, vulcanization is performed at 180°C for 20 minutes (160-250°C, 5-30 minutes is better). Rubber layers with a thickness of 60 μm were formed on both sides. Rubber compound combination ■ Nitrile rubber (NBR) 100 PHR zinc white 5 Stearic acid 0.5 Ketchen Black 30 Graphite 100 Radical receptor 2 Anti-aging agent 7.5 Sulfur
1.5 Vulcanization accelerator
3 Rubber liquid composition Compound ■Rubber 25% by weight toluene
45 Propyl acetate 30 A rubber-coated gasket material having a total thickness of 0.38 cm was obtained in the above manner. Example [2] A rubber-coated gasket material with a total thickness of 0.5 cm was obtained using a cold rolled steel plate with a thickness of 0.25 cm and in the same manner as in Example [1]. However, it differs from Example [11] in that the rubber layer coating thickness was 1204 m on one side. Example [3] Using a cold rolled steel plate having a thickness of 0.25 mm, a rubber-coated gasket material having a total thickness of 0.39 mm was obtained in the same manner as in Example [11]. However, the difference from Example [1] was that the main component rubber used in the primer was the above-mentioned formulation (2), and the rubber layer coating thickness was 65 μm on one side. Example

[4] A rubber-coated gasket material with a total thickness of 0.3 m was obtained using a cold-rolled steel plate with a thickness of 0.2 .mu.m in the same manner as in Example [1]. However, the difference from Example [1] was that the coating rubber compound used for the rubber layer was the following formulation (2), and the rubber layer coating thickness was 45 μm. Rubber compound formulation V Nitrile rubber (NBR) 100 PHR zinc white 5 Stearic acid 0.5 Ketjen Black 20 Graphite 70 Radical acceptor 1 Anti-aging agent 7.5 Sulfur
1.5 Vulcanization accelerator
3 Example [5] Example using a cold rolled steel plate with a thickness of 0.2-

A rubber-coated gasket material having a total thickness of 0.4 mm was obtained in the same manner as in [1]. However, the difference from Example [11] was that the coating rubber compound used for the rubber layer 4 was the following formulation (2), the primer layer thickness was 10 μm, and the rubber layer coating thickness was 65 μm. Rubber compound combination■ Nitrile rubber (NBR) 100PHR zinc white. Stearic acid 0.5 Acetylene black 60 Graphite 60 Radical receptor 1 Anti-aging agent 7.5 Sulfur
1.5 Vulcanization accelerator
3 Example [6] Using a stainless steel plate (SUS304) with a thickness of 0.2 mm, a rubber-coated gasket material with a total thickness of 0.41 m was obtained in the same manner as in Example [1]. However, the difference from Example [1] was that the chemical conversion treatment was performed using an oxalate system, the primer treatment conditions were 150° C. for 3 minutes, and the rubber layer coating thickness was 100 μm. Example [7] Using an aluminum steel plate with a thickness of 0.25 mm, Example [1
] A rubber-coated gasket material having a total thickness of 0.36 m was obtained in the same manner as described above. however. The difference from Example [1] is that the chemical conversion treatment was performed by chromate treatment, and the thickness of the rubber layer was 50 μm. Comparative Example [11] A rubber-coated gasket material having a total thickness of 0.38 mm was obtained in the same manner as in Example [1]. however. The following points differ from Example [1]. The rubber compound formulation and rubber liquid formulation used for the rubber layer are shown below. Rubber compound combination■ Nitrile rubber (NBR) 100PHR zinc white 5 Stearic acid 0.5MT carbon
150 anti-aging agent
7.5 Sulfur 1
．． 5 Vulcanization accelerator 3 Rubber liquid formulation ■ (viscosity 4000 cp) Compound ■ Rubber 40% by weight toluene
40 Propyl acetate 30 Comparative Example [2] After forming a primer layer by the same method as in Example [1], an attempt was made to form a rubber layer using the following rubber liquid formulation, but the viscosity of the rubber liquid was high and formation was difficult. It was difficult. Rubber compound combination■ Nitrile rubber (NBR) 100PHR zinc white 5 Stearic acid 0.5 Ketjen Black 30 Anti-aging agent 7.5 Sulfur
1.5 Vulcanization accelerator
3 Rubber liquid compound (viscosity 100,000 cp or more) ■Rubber 25% by weight toluene
45 Propyl acetate 30 Comparative Example [31 A rubber-coated gasket material having a total thickness of 0.38 mm was obtained in the same manner as in Example [11]. however. The following points differ from Example [11]. The rubber compound formulation is shown below. Rubber compound combination ■ Nitrile rubber (NBR) 100 PHR zinc white 5 Stearic acid 0.5 Ketjen black 30 Graphite 100 Anti-aging agent
7.5 sulfur
1.5 Vulcanization Accelerator 3 The rubber-coated gasket material obtained as described above has an uneven surface because the rubber solution contains carbon gel (insoluble matter). The appearance was poor. A test piece with a length and width of 150 mm was prepared from the rubber-coated gasket material obtained in each of the above examples, and the resistance (surface resistance, Ω/ The results of measuring the resistance (volume specific resistance, Ω・载) between A and B are shown in the table below. 1 1 Surface resistance (Ω/mouth) 1 Volume resistivity (Ω
・cm) 11 3, OXIO” 1,
IXIO"# 2 3.IXIO" 1
,5x10#3 2. OX10” 7
．． 811 4 2.8X10” 8.4X
10# 5 3.5x101, 4x10"# 6
2.9X10” 1.2X107F
F 3.0X10" 1, IXlo"
Four comparative months 1, OXIO" or more 1, OX10"
II #21 Difficulty forming rubber layer
1 #31 Poor Appearance (Surface Irregularities)-1 [Effects of the Invention 1 As described above, according to the present invention, conductive carbon black, graphite, and a radical acceptor are added to the rubber layer formed on the surface of the metal plate. Because it uses nitrile rubber, it can provide higher conductivity than conventional rubber-coated gasket materials. In addition, according to the present invention, by using a rubber as the main component of Primer H containing carbon black other than conductive carbon black, or containing conductive carbon black. By changing the types and amounts of conductive carbon black, graphite, and radical receptors used in the rubber layer, the volume resistivity can be increased by 1.
Rubber-coated gasket materials having various conductivities in the range of 0.7Ω·1 to 10Ω·l can be easily obtained. It can be made to correspond to each required characteristic.

[Brief explanation of the drawing]

The drawing is a sectional view of a rubber-coated gasket material showing an embodiment of the present invention. l-...Metal plate, 2... Old chemical conversion treatment layer, 3... Primer layer, 4... Old...
--Rubber layer, 5.Old...-Non-adhesive layer. Patent applicant NICHIAS Co., Ltd. agent Patent attorney Takezaburo Nagata Points A Points A Procedural amendment 1, Indication of case 1999 Patent Application No. 287944 2, Name of invention Rubber coated gasket material 3, Make amendments Relationship with the Patent Case Patent Applicant Address Name NICHIAS Co., Ltd. 4, Agent 105 Address Shiba 3-chome Building, 3-2-14 Shiba, Minato-ku, Tokyo Phone: (03) 455-8746 Name (7238) Patent Attorney Takeshi Nagata Sanbu, 1-′-～-1%-,,: Revised 1 5. Subject of correction.
′-′-ψ (Contents of amendment) 1. Specification page 11, line 9 r100kgal/loogJ
Correct it to rlooffl/100gJ. 2, page 13, line 19, “Aromatic and hydrocarbon solvents” [
Corrected to aromatic hydrocarbon solvent J. 3. On page 14, line 5 of the same page, correct the following: [by Jttr]. 4, page 20, line 14 rsUs301 to rSUS301
J, and lines 17-18, ``The chemical conversion treatment is performed using an oxalate system, and J is deleted.'' do. 6, page 8 of the same page, “In the formulation table of rubber compound formulation II,
[Antioxidants 1 to 7] is corrected to ``Antioxidants 1 to IOJ.'' 7. Page 16 of the same page, ``Rubber compound compound layer,'' Page 17, ``Rubber compound compound IVJ,'' page 19, ``Rubber compound compound VJ.'' , p. 20 “Rubber compound blend layer 4
．． Page 21 “Rubber Compound Compound Layer”, Page 22 “
In the formulation table of "Rubber compound blend layer" and "Rubber compound blend layer" on page 23, "zinc white,""stearicacid,""coumarone indene resin,""antiagingagent,""
The composition values for ``sulfur'' and ``vulcanization accelerator'' are corrected as shown below. "Zinc white 3~1° Stearic acid 0.3~1.5 Coumarone indene resin 20~6° Anti-aging agent 1
-10 sulfur o, 5-4 vulcanization accelerator -1-7"

Claims (2)

[Claims] (1) In a gasket material in which a rubber layer is formed on one or both sides of a metal plate, the rubber that is the main component of the rubber layer, or the rubber layer and the primer layer contains conductive carbon black, graphite, and a radical acceptor. A rubber-coated gasket material made of nitrile rubber, characterized by a rubber layer and a metal plate bonded together with a primer layer. (2) Conductive carbon black, such as Ketjen black, acetylene black, SAF carbon, etc., with an average particle size of 50 μm or less, and D. B. P absorption amount 100cm^
2/100g and iodine absorption of 50mg/g or more at 10-150PHR, as graphite, scaly graphite, earthy graphite, etc. at 50-200PHR, as a radical acceptor, α,α-diphenyl-β-picryl The rubber-coated gasket material according to claim 1, wherein the rubber layer is formed of nitrile rubber containing hydrazyl or the like in a proportion of 0.5 to 5 PHR.