JPS63264691A - Composite gasket material and production of the same - Google Patents

Abstract

PURPOSE:To obtain the title material used for preparing a gasket having excellent sealing properties at low cost, by forming foam-free rubber layers on both sides of a metallic substrate sheet and thereafter forming foam rubber layers on the surface thereof. CONSTITUTION:A non-foamable rubber soln. contg. a rubber material, such as a natural rubber, a synthetic rubber and a thermoplastic elastomer, and optionally a rubber compounding agent, such as a vulcanizing agent (promoter), a retardant and a reinforcing agent, is applied to both sides of a metallic substrate sheet 2 (e.g., steel plate) optionally surface treated. Drying and vulcanization are performed to form foam-free rubber layers 4 having a thickness of 2mum or more. Subsequently, a foamable rubber soln. comprising a rubber and a thermoplastic rubber, a heat-decomposable foaming agent (e.g., dinitropentamethylenetetramine) and optionally a foaming auxiliary, a rubber compounding agent and/or a rubber solvent is applied to the surfaces of foam- free rubber layers 4. After drying, the whole is heated so as to conduct foaming and vulcanization, thereby forming foam rubber layers 3 having a density of 10-800kg/m<3> and a thickness of 0.05-2mm. Thus, a composite gasket material 1 is prepd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a composite gasket material for obtaining a gasket with good sealing properties and a method for manufacturing the same.

(Prior art) Composite gasket materials have been proposed as gasket materials with good sealing properties, which are made by bonding plastic or rubber elastic foam to both sides of a base sheet made of an impermeable material. .

That is, JP-A-54-72282 discloses a composite gasket material in which foam layers having closed cells are formed on both sides of an impermeable base sheet with little elasticity. However, this gasket material is made by forming a foam on a base sheet with a dense impermeable structure, and is a direct composite of an impermeable material and a foam, which are materials with significantly different physical properties. Because it is,
The bonding strength between the two is very small, so in the process of cutting a gasket of the desired shape from this gasket material,
There are serious drawbacks in terms of productivity, performance, economy, etc., such as the two peeling off, or even if they do not peel off, the sealing performance deteriorates. This publication also describes a method for manufacturing the above-mentioned composite gasket material, in which various compounding agents are added to a polymer component consisting of acrylic emulsion or latex alone or in combination, and the mixture is stirred at high speed in the presence of air to form a wet foam. The wet foam is applied onto an impervious base sheet selected from a polyester resin sheet, a polyamide resin sheet, a polyurethane resin sheet, a polyacrylic resin sheet, and paper, and then heated to gel the wet foam. A method for subsequently carrying out a crosslinking reaction is disclosed.

However, foams formed by stirring acrylic emulsion or latex at high speed in the presence of air to form foams, and then performing gelation and crosslinking reactions,
The percentage of closed cells is low at approximately 30% or less, and the cells are irregular and irregular, so when used as a gasket, the foam tends to leak, and has low sealing performance. It is very difficult to bond wet foams made of emulsion or latex to a level that has practical strength, and this method is especially impossible when composited with metal sheets.

Furthermore, Japanese Patent Application Laid-Open No. 52-38579 discloses that a foamable plastic layer is layered on a metal sheet using means such as powder coating of foamable plastic, heat-sealing of the foamable plastic sheet, or adhesive bonding. , a method for producing a composite material of a metal sheet and a foamed plastic is disclosed in which the foamable plastic layer is foamed by heating. It is impossible to completely eliminate the presence of air at and/or in the vicinity of the plastic layer. Therefore, when the foamable plastic layer is foamed and heated, the air existing at the interface and/or in the vicinity of the two expands significantly, creating large air bubble cavities at the interface and/or within the foamed plastic layer.
As a result, the adhesion strength between the metal sheet and the foamed plastic layer decreases, and the size of the bubbles in the foamed plastic varies widely, the number of closed cells decreases, and the surface smoothness deteriorates. Furthermore, in the manufacturing method disclosed herein, since the metal sheet and the foamed plastic are directly composited as described above, the adhesive strength between the metal sheet and the foamed plastic is low, and air is present at this interface. Coupled with this, defects such as partial peeling of the foamable plastic occur due to the heating action and foaming force during foaming of the foamable plastic.

(Problems to be Solved by the Invention) This invention eliminates all the drawbacks of the conventional composite gasket materials mentioned above, has extremely excellent performance, has high reliability in terms of quality, and has high productivity. The object of the present invention is to provide an economical composite gasket I/material and a method for manufacturing the same.

(Means for Solving the Problems) The present inventors coated a non-foaming rubber solution on both sides of a metal base sheet, dried and vulcanized the non-foamed rubber layer, and further coated the surface of the non-foamed rubber layer. A metal base sheet is formed by applying a foaming rubber solution, drying it to form a foaming rubber layer, and then heating it to foam and vulcanize the foaming rubber layer. It was discovered that a composite gasket material in which a foamed rubber layer, a foamed rubber layer, a non-foamed rubber layer, and a non-foamed rubber layer were combined into an integral structure by the self-adhesion of the rubber layer was suitable for this purpose, and based on that knowledge, they completed this invention. This is what I did.

That is, the composite gasket material of the present invention is characterized in that foamed rubber layers are bonded to each of both sides of a metal base sheet via a non-foamed rubber layer by the self-adhesive action of each rubber layer. The manufacturing method of the composite gasket material of the invention includes applying a non-foaming rubber solution to both sides of a metal base sheet, followed by drying and vulcanization to form a non-foamed rubber layer, and then applying a non-foamed rubber solution to the surface of the non-foamed rubber layer. A foamed rubber solution is applied to the foamed rubber solution, dried to form a foamed rubber layer, and then heated to foam and vulcanize the foamed rubber layer to form a foamed rubber layer. It is something to do.

Next, the composite gasket material of the present invention will be explained in detail based on the accompanying drawings showing embodiments thereof.

FIG. 1 is a sectional view of a composite gasket material showing an embodiment of the present invention.

In the drawing, 1 is a composite gasket material, in which a foamed rubber layer 3 is formed on both sides of a base sheet 2 made of gold or synthetic material through a non-foamed rubber layer 4, utilizing the self-adhesive action of each rubber layer 3.4. In other words, the three parts are joined into an integral structure without using a separate adhesive.

The base sheet 2 used in this invention is a metal sheet that has no omissions, has excellent processability, can reinforce the foamed rubber layer 3, and has excellent adhesiveness with the non-foamed rubber layer 4. suitable. Preferred specific examples include metal sheets such as mild steel plates, stainless steel plates, and aluminum plates.

The material of the non-foamed rubber layer 4 formed on the base sheet 2 in this invention is selected from natural rubber, synthetic rubber, thermoplastic elastomer, etc. depending on the purpose, and the thickness of the non-foamed rubber layer 4 is It is preferably 2 μm or more, particularly 10 μm or more. The upper limit of the thickness is not critical and is selected depending on the purpose, but it is generally made approximately equal to the thickness of the foamed rubber layer 3 described later. The non-foaming rubber solution used in the method of this invention is made by using one or more of the above-mentioned rubber materials such as natural rubber, synthetic rubber, and thermoplastic elastomer, and adding a vulcanizing agent (crosslinking agent) and a vulcanizing agent. The type and amount of known rubber compounding agents such as accelerators (crosslinking accelerators), retarders, reinforcing agents, anti-aging agents, softeners, tackifiers, flame retardants, fillers, and colorants are adjusted according to the purpose. It is a liquid composition that is appropriately selected and blended, and further contains a rubber solvent.

The foamed rubber layer 3 in this invention is a foamed layer of natural rubber, synthetic rubber, thermoplastic elastomer, etc., and the density and thickness of the foamed rubber layer 3 are appropriately selected depending on the purpose, but generally The density is 10-800/I
I'', the thickness is 0.05-2 nn.

In addition, the foamable rubber solution used in the method of this invention is a rubber material selected from the above various rubber materials, either singly or in combination of two or more, according to the purpose, and is mixed with a known rubber compound in the same way as the non-foamable rubber solution. This liquid composition is made by blending a foaming agent and a rubber solvent, and further blending a thermally decomposable foaming agent and, if necessary, a foaming aid such as urea or an organic acid (salt). Examples of the thermally decomposable blowing agent include nitroso compounds such as dinitropentamethylenetetramine, azo compounds such as azodicarbonamide, and sulfonyl hydrazide compounds such as oxybisbenzenesulfonyl hydrazide.
Note that a polymer compound such as EVA or a phenol resin precursor or a precursor thereof may be appropriately blended into the non-foamable rubber solution and the foamable rubber solution.

In the manufacturing method of the present invention, the surface of the metal base sheet 2 is first cleaned before use, but it is preferable to perform surface treatments such as etching, sanding, and primer coating as necessary to improve adhesion.

After that, a non-foaming rubber solution is applied to the surface of the base sheet 2, then dried, and further heated and vulcanized to form a non-foamed rubber layer 4 directly on the base sheet 2 by self-adhesion. do. In this case, the degree of vulcanization may be increased to a level at which the non-foamed rubber layer 4 does not peel off from the metal base sheet 2 due to swelling or the like when the next foamable rubber solution is applied.

This can be easily determined experimentally and its extent is related to the magnitude of the self-adhesive effect between it and the foamed rubber layer 3.

Furthermore, the foamed rubber NJ3 in the present invention is produced by applying a foaming rubber solution to the surface of the non-foaming rubber layer 4, drying to form a foaming rubber layer, and then heating to foam and vulcanize. As a result, the foamed rubber layers 3 are integrally bonded to both sides of the base sheet 2 via the non-foamed rubber layers 4, and the composite gasket material 1 is obtained.

(Function) In this invention, a non-foaming rubber solution is applied to both sides of a metal base sheet, dried and vulcanized to form a non-foaming rubber layer, and a foaming rubber solution is further applied to the surface of the non-foaming rubber layer. Since the foamed rubber layer is formed by heating and then heated to foam and vulcanize the foamed rubber layer, there is a possibility that air may enter the joint between the base sheet, the non-foamed rubber layer, and the foamed rubber layer. The presence of foreign substances such as the presence of voids that adversely affect the adhesive strength of each constituent material is completely eliminated, and the foamed rubber layer is not a base sheet with significantly different properties, but a non-foamed rubber layer of almost the same quality. Since it is formed by foaming an adhesively formed foamable rubber layer, the presence of air in the joints and voids due to peeling etc. are completely eliminated when the foamable rubber layer is foamed, and the non-foamed rubber layer is Since the bonded foam rubber layer is foamed, the stress from foaming does not remain at the bonded portion of the foam rubber layer, and the adhesion of each component material is perfect. Therefore, it is possible to completely prevent the occurrence of practically harmful phenomena such as peeling of constituent materials due to physical, mechanical, and chemical effects during secondary processing or during practical use.

Furthermore, according to the present invention, the foamed rubber layer is formed by foaming a foamable rubber layer that is integrally formed from a solution on the non-foamed rubber layer by its self-adhesive action using a thermally decomposable foaming agent. Therefore, bubbles with a fine radius and high uniformity are formed, and almost all of the bubbles have a closed cell structure, and the surface smoothness is excellent, and as mentioned above, the adhesion of each constituent material is perfect. Therefore, the occurrence of phenomena such as substance leakage from the gasket that would cause the sealing material to lose its function is completely eliminated. Has performance.

(Example) Next, the present invention will be described in more detail in Examples.

Example 1 A non-foaming rubber solution shown below was applied to both surfaces of a surface-cleaned steel plate with a thickness of 0.2511I, and heated at 160°C for 2 minutes to form a non-foaming rubber layer (thickness 10 to 20All). Formed. Next, a foamable rubber solution having the following composition was applied to the surface of this non-foamed rubber layer, and this was dried to form a foamable rubber layer (thickness 0.3 nn +
), then heated at 100°C for 10 minutes, and then further heated for 16 minutes.
Heating was performed at 0° C. for 20 minutes to obtain a composite gasket material in which the three components were completely bonded together and had a foamed rubber layer with a smooth surface composed of microbubbles with a thickness of 0.8 nl.

From this one 33x53φ (IIn) and 81 x
We produced a composite gasket punched to 99φ (11),
Tighten with a pressure of 5kgf/cn+' and 5k with nitrogen gas.
A sealing experiment was conducted by loading c+f/C112. As a result, no leakage was observed in any of the specimens.

The composition of the rubber solution used here is as follows.

Non-foaming rubber solution (unit: PHR) N B R100 Zinc white 5 Stearic acid 1 Carbon black 80 Soft calcium carbonate 30 Adhesive sealant 40 Vulcanization accelerator 3 Sulfur 2 M E K 1343 Foaming foamable rubber stratigraphy PHR ) N B R100 Zinc white 5 Stearic acid 1 Carbon black 80 Soft calcium carbonate 30 Tackifier 15 Anti-aging agent 5 Stabilizer 1 Vulcanization accelerator 3 Sulfur 1.5 Foaming agent (ADCA type) 6 M E K 372 Examples 2 Form a non-foamed rubber layer in the same manner as in Example 1, apply the foamable rubber solution used in Example 1 on its surface, and dry to obtain a foamable rubber layer (thickness: 0.1 m+a).

Then, it was heated at 160°C for 20 minutes to a thickness of 0.1711
A composite gasket material was obtained in which a steel plate, a non-foamed rubber layer, and a foamed rubber layer were integrally bonded to each other, and the foamed rubber layer had a smooth surface made of n microscopic cells.

A seal test of this product was conducted in the same manner as in Example 1. As a result, no leakage was observed, and excellent sealing performance was confirmed.

Example 3 A non-foamed rubber layer (40 to 50μ thick
m), and then the foamable rubber solution used in Example 1 is applied to its surface and dried to form a foamable rubber layer (thickness 0.
2+nn) and then incubated at 140°C for 5 min at 16
Heating was carried out at 0°C for 10 minutes to obtain a composite gasket in which each constituent material was integrally bonded, having a foamed rubber layer with a thickness of 0.5 nm and a smooth surface made of &1 fine cells.

A sealing test was performed on this product in the same manner as in Example 1, and no leakage was observed.

(Effects of the Invention) As described above, the composite gasket material according to the present invention has a foamed rubber layer integrally bonded to a metal base sheet via a non-foamed rubber layer, so this can be used as a gasket. Even when exposed to various effects during secondary processing or during actual use, there is no practically harmful phenomenon such as peeling of each constituent material, and the adhesion of each constituent material is perfect. Further, according to the method of the present invention, a non-foamed rubber layer is formed on the surface of the base sheet using a rubber solution, and then a foamable rubber layer is formed from the solution in the same way as the non-foamed rubber layer, and this is heated and foamed. Therefore, the presence of voids that would reduce adhesion is completely eliminated at the joints of each material, and both materials are bonded to a non-foamed rubber layer with specific axially similar properties. The foamable rubber IQ foams smoothly without any abnormal stress occurring at the bonded parts, and as mentioned above, there are no voids, etc., so there are no voids etc. in the joints with each constituent material and/or inside that are harmful to adhesion. This eliminates foreign matter and provides excellent adhesion, and forms a foamed rubber layer with an excellent surface smoothness with uniform, fine bubbles, so when used as a gasket, it can be used even at low tightening pressures. It has extremely excellent performance such as obtaining a seal that is
A composite gasket with high reliability!・Materials can be obtained.
In addition, the present invention has excellent economic efficiency and productivity, such as being extremely easy to implement using extremely easily available materials, and has extremely high industrial utility value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a composite gasket material showing an embodiment of the present invention. 1... Composite gasket material, 2... Base sheet,
3... Foamed rubber layer, 4... Non-foamed rubber layer. Composite gasket material = 1 Figure 1

Claims (1)

[Scope of Claims] 1. A composite gasket material characterized in that foamed rubber layers are bonded to both surfaces of a metal base sheet via a non-foamed rubber layer by the self-adhesive action of each rubber layer. 2. Applying a non-foaming rubber solution to both sides of a metal base sheet, then drying and vulcanizing to form a non-foaming rubber layer, then applying a foamable rubber solution to the surface of the non-foaming rubber layer, A method for producing a composite gasket material, which comprises drying the material to form a foamable rubber layer, and then heating the material to foam and vulcanize the foamable rubber layer to form a foamed rubber layer.