JP7253899B2 - Gasket paste and gasket - Google Patents

Description

The present invention relates to gasket pastes and gaskets.

2. Description of the Related Art Conventionally, gaskets have been widely used to seal leakage paths of various fluids in a wide range of fields such as petrochemical plants, various industrial machinery, automobiles and home appliances.

In general, gaskets are made of rubber plates, joint sheets made by mixing rubber, fillers, reinforcing fibers, etc. into sheets, fluororesin sheets made by mixing fillers into fluororesin, metal plates, and A wide variety of gaskets are used, such as sheet-like gaskets obtained by cutting various sheet-like materials such as composite sheets of metal and various materials, and molded gaskets obtained by molding the above-mentioned various materials into predetermined shapes.
By attaching these gaskets to piping flanges or housings and applying an appropriate tightening load, the gaps formed on the contact surface between the gasket and the mating member are eliminated, making it possible to seal the fluid. Become.

On the other hand, in recent years, as environmental problems have been emphasized, it is an urgent need in all fields to improve the sealing performance of the gasket and further reduce the internal fluid leaking from the contact surface with the mating member.
In principle, the tightening load can be increased to improve the sealing performance of the gasket. It also leads to compression failure of the gasket itself, and there is a limit.

Therefore, gasket paste has been proposed as a measure to improve the sealing performance of gaskets. This gasket paste is applied to the surface of a gasket made of various materials, and is applied to the gasket and the flange or joint that fastens it. By arranging the gasket while filling the gap between the gasket and the mating material when the mating material such as the housing is tightened, it is possible to assist and improve the sealing performance (for example, Patent Document 1 (International See Publication No. 2017/109880)).

International Publication 2017/109880

By the way, when a certain tightening load is applied to a gasket, the gasket deforms, especially under high temperature conditions, and the pressure between the gasket and the flange joint surface of the pipe decreases (resulting in stress relaxation), resulting in a decrease in sealing performance. It is known that

That is, when a tightening load is applied to the gasket, the gasket is first compressed in the thickness direction by the tightening load, and then deformed in the radial direction. Then, the internal fluid gradually begins to leak, and when the deformation in the radial direction exceeds the strength limit of the material, the gasket breaks and a large amount of the internal fluid leaks.

The deformation in the radial direction is greatly affected not only by the strength of the gasket, but also by the friction on the contact surface between the gasket and the mating material. It is said that raising is effective in preventing deformation.

On the other hand, the inventors of the present invention have studied the gasket paste, which has the effect of filling the gap between the gasket and the mating material to improve the sealing performance, but on the other hand, it contains oil and the like, so it is difficult for the gasket and the mating material. It was found that the contact surface of the gasket tends to be slippery and tends to reduce the coefficient of friction on the contact surface, and as a result, it can promote deformation of the gasket in the radial direction.

Under such circumstances, an object of the present invention is to provide a gasket paste and a gasket that can exhibit stable sealing performance over a long period of time while suppressing radial deformation of the gasket. .

As a result of intensive studies by the present inventors in order to achieve the above objects, it was found that the above problems could be solved by a gasket paste made by dispersing calcined clay in oil or in water containing a surfactant. , and have completed the present invention based on this knowledge.

That is, the present invention
(1) Gasket paste characterized by calcined clay dispersed in oil or water containing a surfactant;
(2) The gasket paste according to (1) above, wherein the calcined clay is calcined kaolin;
(3) The gasket paste according to (1) or (2) above, wherein the calcined clay has an average particle size of 30 μm or less,
(4) The gasket paste according to any one of (1) to (3), further comprising dispersed powdery fluororesin;
(5) A gasket characterized by having a coating layer made of the gasket paste according to any one of (1) to (4) on its surface,
It provides

According to the present invention, it is possible to provide a gasket paste and a gasket that can exhibit stable sealing performance over a long period of time while suppressing radial deformation of the gasket.

The gasket paste according to the present invention is characterized in that calcined clay is dispersed in oil or in water containing a surfactant.

In the gasket paste according to the present invention, examples of oils include natural oils such as camellia oil, olive oil, castor oil, peanut oil, tea oil, sesame oil, rapeseed oil, linseed oil, perilla oil, soybean oil, and avocado oil, and liquid paraffin. Hydrocarbon oils such as dimethylsiloxane, silicone oils such as methylphenylsiloxane, perfluoropolyether oils, fluorine oils such as chlorotrifluoroethylene oil, etc., but the present invention is not limited to these. And each may be used independently and may use two or more types together.

In the gasket paste according to the present invention, the surfactant is not particularly limited as long as it can disperse the filler contained in the paste. One or more selected from ionic surfactants, amphoteric surfactants and the like can be used, and among these, nonionic surfactants are preferred.

Examples of the nonionic surfactant include ether-type, ether-ester-type, ester-type, and nitrogen-containing-type nonionic surfactants. Examples of ether-type nonionic surfactants include poly One or more selected from oxyethylene alkyl and alkylphenyl ethers, alkyl allyl formaldehyde condensed polyoxyethylene ethers, polyoxyethylene polyoxypropylene block copolymers, polyoxyethylene polyoxypropyl alkyl ethers, etc. can be mentioned. Examples of nonionic surfactants include one or more selected from polyoxyethylene ethers of glycerol esters, polyoxyethylene ethers of sorbitan esters, polyoxyethylene ethers of sorbitol esters, and the like. Examples of active agents include one or more selected from polyethylene glycol fatty acid esters, glycerin esters, polyglycerin esters, sorbitan esters, propylene glycol esters, sucrose esters, etc. Nitrogen-containing nonionic surfactants Examples thereof include one or more selected from fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, and the like.
Among the above nonionic surfactants, ether-type surfactants are preferred, and polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers are particularly preferred in terms of dispersibility.

By containing a surfactant in the gasket paste according to the present invention, it is possible to easily disperse other ingredients.
The type of surfactant and its content in water may be appropriately determined according to the ingredients to be dispersed.

In the gasket paste according to the present invention, water used together with the surfactant includes ion-exchanged water (deionized water) and purified water such as distilled water.

In the gasket paste according to the present invention, the calcined clay may be, for example, one or more selected from calcined kaolin, calcined diatomaceous earth, etc., and calcined kaolin is preferred.

Calcined clay is made by calcining natural minerals at a high temperature, and since it is in a state where water of crystallization is released and surface activity is enhanced, it is easy to improve the adhesiveness or bonding strength with the oils that make up the gasket paste. It is considered possible.
In addition, since the calcined clay is calcined at a high temperature to burn off the organic matter, it is porous. It is thought that the adhesiveness or bonding strength can be further improved by increasing the adhesiveness.
In this way, since the gasket paste contains calcined clay, the bonding strength between the ingredients of the gasket paste is improved, and as a result, separation, decomposition, volatilization, etc. of the ingredients are suppressed, and the sealing effect is improved. It is thought that it will be maintained for a long time.

In particular, when the calcined clay is calcined kaolin, when kaolin is calcined at a high temperature to produce calcined kaolin, the scale-like primary particles that form kaolin by the high temperature calcination aggregate with each other while maintaining the scale shape. When calcined kaolin is used as a compounding component of a gasket paste, in order to form complex secondary particles and increase the friction coefficient due to the unevenness derived from the scale shape, the calcined kaolin is interposed between the calcined kaolin and the gasket. It is thought that the slipperiness on the contact surface with the material can be preferably reduced.

In the gasket paste according to the present invention, the baked clay preferably has an average particle size of 30 μm or less, more preferably 0.5 to 10 μm, and even more preferably 0.5 to 2 μm.
In this application document, the average particle size of the calcined kaolin is obtained by irradiating a laser beam in the state of an aqueous dispersion using a laser diffraction/scattering particle size distribution analyzer and measuring the degree of frequency modulation of the scattered light. It means the value ( _D50 ) at 50% cumulative frequency in the diameter cumulative frequency distribution curve.

In the gasket paste according to the present invention, since the baked clay has an average particle size of 30 μm or less, when blended in the gasket paste, it more effectively suppresses the reduction in the coefficient of friction and prevents the gasket from becoming a mating material. It is thought that the slipperiness on the contact surface can be suitably suppressed.

The gasket paste according to the present invention preferably contains 3 to 60% by mass of calcined clay when converted to solid content (when the total solid content contained in the paste is 100% by mass). More preferably 55% by mass, more preferably 10 to 50% by mass.
Since the gasket paste according to the present invention contains the calcined clay in the above ratio, it is possible to exhibit stable sealing performance over a long period of time while suppressing deformation in the radial direction of the gasket.

The gasket paste according to the present invention may further contain dispersed and blended powdery fluororesin.

In the gasket paste according to the present invention, as the fluororesin constituting the powdery fluororesin, conventionally known fluororesins can be selected, such as tetrafluoroethylene resin (PTFE), modified PTFE, tetrafluoroethylene-hexa Fluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), ethylene-tetra One or more selected from fluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE) and the like can be mentioned.

The gasket paste according to the present invention preferably contains 20 to 60% by mass of powdered fluororesin when converted to solid content (when the total solid content in the paste is 100% by mass). More preferably 30 to 50% by mass, more preferably 35 to 45% by mass.
Since the gasket paste according to the present invention contains the fluororesin in the above ratio, the fluororesin particles are easily deformed by the tightening force of the flange, etc., fill the gaps and gaps between the gasket and the flange, etc., and lower the tightening. Sealability can be demonstrated by force.

In the gasket paste according to the present invention, the powdery fluororesin preferably has an average particle size of 0.3 to 30 μm, more preferably 0.3 to 10 μm.
Such a powdery fluororesin is excellent in dispersibility in the paste, is excellent in heat resistance, chemical resistance, etc., and can easily exhibit excellent sealing properties in a wide temperature range.

In this application document, the average particle size of the powdered fluororesin is obtained from the degree of frequency modulation of scattered light obtained by irradiating a laser beam in the state of an aqueous dispersion using a laser diffraction/scattering type particle size distribution measuring device. Means the value (D ₅₀ ) at 50% of the cumulative frequency in the cumulative frequency distribution curve of the particle size.

The gasket paste according to the present invention may further contain, as subcomponents, various lubricants, coloring agents such as alumina and titanium oxide, and the like, within the range in which the effects of the present invention can be exhibited.

The gasket paste according to the present invention preferably has a solid content concentration of 10 to 60% by mass, more preferably 15 to 55% by mass, and more preferably 30 to 50% by mass. more appropriate.

In the gasket paste according to the present invention, when the solid content concentration is within the above range, the desired effect can be easily exhibited.

The gasket paste according to the present invention can be prepared, for example, by mixing ingredients such as calcined clay in oil or in water containing a surfactant, using a mixing machine such as a mixer, a kneader, or a roll, and then mixing various ingredients to achieve a predetermined viscosity. It can be easily prepared by uniformly mixing the raw materials in an arbitrary order while adjusting the mixing ratio of the raw materials.

The gasket paste according to the present invention can be used as a paste material by, for example, applying it to the surface of a gasket using a fingertip, a brush, a roll coater, or the like, and then fastening it to a mating material. can be done.

The application amount of the gasket paste according to the present invention is not particularly limited, and may be appropriately adjusted according to the type of gasket to be applied, etc., but is preferably 40 to 350 g/m ² , more preferably 100 to 350 g/m ² . is more preferred, and 150 to 200 g/m ² is even more preferred.

The type of gasket to which the gasket paste according to the present invention is applied is not particularly limited. Examples include a fluororesin sheet obtained by mixing materials and processed into a sheet, and a sheet-like gasket obtained by cutting and processing various sheet-like materials such as metal plates and composite sheets of metal and various materials.

According to the present invention, it is possible to provide a gasket paste capable of exhibiting stable sealing performance over a long period of time while suppressing radial deformation of the gasket.

Next, the gasket according to the present invention will be explained.
A gasket according to the present invention is characterized by having a coating layer formed of the gasket paste according to the present invention on its surface.

The details of the gasket paste according to the present invention are as described above, and the types of gaskets to which the paste is applied and the details of the method of applying the paste (method of forming a coating film) are also as described above.

The compression deformation ratio of the gasket according to the present invention is preferably as small as possible, but the preferable range varies slightly depending on the type of gasket provided with the coating film. When the gasket provided with the coating film is the joint sheet described above, the compression deformation ratio 25% or less is preferable, 20% or less is more preferable, and 18% or less is even more preferable.
Further, when the gasket provided with the coating film is the above-mentioned fluororesin sheet, the compressive deformation rate is preferably 85% or less, more preferably 75% or less, and even more preferably 70% or less.

In the present application documents, the compressive deformation rate of a gasket means a value calculated by the calculation method shown below.
<Method for calculating compression deformation rate>
A gasket material was cut into a disk-shaped object having a thickness of _3.0 mm and a diameter of 25.4 mm to form a sheet gasket. demand.
The above gasket paste was evenly applied with fingertips to both main surfaces of the obtained sheet-like gasket so that the coating amount was 170 to 200 g/m ² , and left to stand.
Next, using a hot press heated to 100° C., the gasket to which the gasket paste was applied was compressed for 1 minute with a compressive load of 68.6 N/mm ² , and then the major diameter of the gasket deformed into an elliptical shape (maximum Diameter) _D1 and minor diameter (minimum diameter) _D2 are measured respectively.
The change in area before and after the test is calculated as the compression deformation rate using the following formula.
Compression deformation rate (%) = ((D ₁ ×D ₂ -D ₀ ² )/D ₀ ² ) × 100

In the gasket according to the present invention, since the compressive deformation rate is within the above range, it is possible to publicly suppress deformation in the radial direction of the gasket and easily exhibit stable sealing performance over a long period of time. .

According to the present invention, it is possible to provide a gasket that can exhibit stable sealing performance over a long period of time while suppressing radial deformation.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, which are merely illustrative and do not limit the present invention.
In the examples and comparative examples shown below, compression deformation resistance evaluation 1 (compression deformation resistance 1), compression deformation resistance evaluation 2 (compression deformation resistance 2), sealing property evaluation, state stability evaluation, coating Evaluation of workability and evaluation of anti-drip property were performed by the methods shown below.

(Compressive deformation resistance 1)
A joint sheet containing acrylonitrile-butadiene rubber (NBR), aramid fiber and inorganic filler (manufactured by NICHIAS Corporation, product number TOMBO No. 1995, thickness 3.0 mm) was cut into a disk-shaped object with a diameter of 25.4 mm. A sheet-like gasket was produced, and the diameters were measured at two orthogonal points to obtain an average value (D ₀ ).
The above gasket paste was evenly applied with fingertips to both main surfaces of the obtained sheet-like gasket so that the coating amount was 170 to 200 g/m ² , and left to stand.
Next, using a hot press heated to 100° C., the gasket to which the gasket paste was applied was compressed for 1 minute with a compressive load of 68.6 N/mm ² , and then the major diameter of the gasket deformed into an elliptical shape (maximum diameter) _D1 and minor diameter (minimum diameter) _D2 were measured respectively.
The change in area before and after the test was calculated as the compression deformation rate using the following formula.
Compression deformation rate (%) = ((D ₁ ×D ₂ -D ₀ ² )/D ₀ ² ) × 100

(Compressive deformation resistance 2)
A fluororesin (polytetrafluoroethylene) gasket (manufactured by NICHIAS Corporation, product number TOMBO No. 1133, thickness 3.0 mm) is cut into a disk-shaped object with a diameter of 25.4 mm to form a sheet gasket. At the same time, the diameters at two orthogonal locations were measured, and the average value (D ₀ ) was obtained.
The above gasket paste was evenly applied with fingertips to both main surfaces of the obtained sheet-like gasket so that the coating amount was 170 to 200 g/m ² , and left to stand.
Next, using a hot press heated to 100° C., the sheet-like gasket coated with the gasket paste was compressed for 1 minute with a compressive load of 68.6 N/mm ² , and then the sheet-like gasket deformed into an elliptical shape. The major diameter (maximum diameter) _D1 and the minor diameter (minimum diameter) _D2 of each were measured.
The change in area before and after the test was calculated as the compression deformation rate using the following formula.
Compression deformation rate (%) = ((D ₁ ×D ₂ -D ₀ ² )/D ₀ ² ) × 100

(sealing property)
A joint sheet containing a special blend rubber, aramid fiber and inorganic filler (manufactured by NICHIAS Corporation, product number TOMBO No. 1993, thickness 3.0 mm) is cut and JIS 10K50A-RF flange standard dimensions (outer diameter 104 mm, A doughnut-shaped product having an inner diameter of 61 mm was produced and used as a sheet-shaped gasket.
The gasket paste was evenly applied with fingertips to both main surfaces of the resulting sheet-like gasket so that the coating amount was 170 to 200 g/m ² and left to stand.
Next, the above sheet-like gasket was mounted between the JIS10K50A-RF flanges and fastened with a compressive load of 34.3 N/mm ² using bolts.
A nitrogen gas of 3 MPa was applied to the hollow portion of the fastening body for 10 minutes, and the amount of leakage was measured by the water replacement method.

(state stability)
After the gasket paste was prepared, it was left to stand at room temperature for 24 hours.
○: Binder and filler are not separated (filler is not sedimented)
×: Binder and filler are separated (filler is sedimented)

(Coatability)
An arbitrary amount of gasket paste was applied to the main surface of a joint sheet containing acrylonitrile-butadiene rubber (NBR), aramid fiber and inorganic filler (manufactured by Nichias Corporation, product number TOMBO No. 1995, thickness 3.0 mm). The coatability was examined and the coatability was evaluated based on the following evaluation criteria.
○: The gasket paste can be easily spread and can be applied evenly ×: The gasket paste cannot be easily spread

(Liquid drip prevention)
A gasket paste was applied to both main surfaces of a joint sheet containing acrylonitrile-butadiene rubber (NBR), aramid fiber and inorganic filler (manufactured by NICHIAS Corporation, product number TOMBO No. 1995, thickness 3.0 mm). After applying the gasket evenly with your fingertips so that the amount is 170 to 200 g/m ² , immediately place the gasket so that the main surface of the gasket is vertical, and visually check for dripping on the coated surface after 30 minutes from the application. Then, the anti-drip property was evaluated based on the following evaluation criteria.
○: no liquid dripping ×: liquid dripping

(Example 1)
Stir and mix using a medicine spoon so that 64% by mass of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) and 36% by mass of calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) are used as oil components. Thus, 78 g of gasket paste was obtained.
Compression deformation resistance 1 and sealability of gaskets obtained from the obtained gasket paste were evaluated based on the evaluation methods described above. Table 1 shows the results.

(Example 2)
As oil content, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 64% by mass, calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 18% by mass, mica (manufactured by Topy Industries, Ltd., average particle size 10 μm). ) was 18% by mass, and 78 g of a gasket paste was obtained by stirring and mixing using a spatula.
Compression deformation resistance 1 and sealability of the gasket by the obtained gasket paste were evaluated in the same manner as in Example 1. Table 1 shows the results.

(Comparative example 1)
Stir and mix using a spatula so that the oil content is 64% by mass of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) and 36% by mass of mica (manufactured by Topy Industries, Ltd., average particle size 10 μm). Thus, 78 g of gasket paste was obtained.
Compression deformation resistance 1 and sealability of the gasket by the obtained gasket paste were evaluated in the same manner as in Example 1. Table 1 shows the results.

(Example 3)
Stir and mix using a spoon so that silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 89% by mass and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 11% by mass as oil. Thus, 78 g of gasket paste was obtained.
The state stability and coatability of the obtained gasket paste, and the compression deformation resistance 1 and compression deformation resistance 2 of the gasket by the obtained gasket paste were evaluated based on the evaluation method described above. Table 2 shows the results.

(Example 4)
Stir and mix using a medicine spoon so that 80% by mass of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) and 20% by mass of calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) are used as oil. Thus, 78 g of gasket paste was obtained.
The state stability and coatability of the obtained gasket paste, and the compression deformation resistance 1 and compression deformation resistance 2 of the gasket by the obtained gasket paste were evaluated based on the evaluation method described above. Table 2 shows the results.

(Example 5)
Stir and mix using a spoon so that silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 69% by mass and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 31% by mass as oil. Thus, 78 g of gasket paste was obtained.
The state stability, coatability, anti-dripping property and sealability of the obtained gasket paste, and the compression deformation resistance 1 and compression deformation resistance 2 of the gasket obtained by the obtained gasket paste were evaluated by the above-described evaluation method. was evaluated based on Table 2 shows the results.

(Example 6)
Stir and mix using a spoon so that silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 50% by mass and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 50% by mass as oil. Thus, 78 g of gasket paste was obtained.
The state stability, coatability, and anti-drip properties of the obtained gasket paste, and the compression deformation resistance 1 and compression deformation resistance 2 of the gasket by the obtained gasket paste were evaluated based on the evaluation method described above. bottom. Table 2 shows the results.

(Example 7)
Stir and mix using a spoon so that silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 43% by mass and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 57% by mass as oil. Thus, 78 g of gasket paste was obtained.
The state stability and anti-drip property of the obtained gasket paste, and the compressive deformation resistance 1 and the compression deformation resistance 2 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 2 shows the results.

(Example 8)
As oil content, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 69% by mass, inorganic filler is 31% by weight, and the weight breakdown of this inorganic filler is calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm). 77% by weight and 23% by weight mica (manufactured by Shiraishi Calcium Co., Ltd., average particle size 13 μm) were stirred and mixed using a scoop to obtain 78 g of gasket paste.
The state stability, coatability and anti-drip property of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 3 shows the results.

(Example 9)
As oil content, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 69% by mass, inorganic filler is 31% by weight, and the weight breakdown of this inorganic filler is calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm). 55% by weight and 45% by weight of mica (manufactured by Shiraishi Calcium Co., Ltd., average particle size 13 μm) were stirred and mixed using a scoop to obtain 78 g of gasket paste.
The state stability, coatability and anti-drip property of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 3 shows the results.

(Example 10)
As oil content, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 69% by mass, inorganic filler is 31% by weight, and the weight breakdown of this inorganic filler is calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm). 32% by weight and 68% by weight mica (manufactured by Shiraishi Calcium Co., Ltd., average particle size 13 μm) were stirred and mixed using a scoop to obtain 78 g of gasket paste.
The state stability, coatability and anti-drip property of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 3 shows the results.

(Comparative example 2)
Stir and mix using a spoon so that silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) is 69% by weight and mica (manufactured by Shiraishi Calcium Co., Ltd., average particle size 13 μm) is 31% by weight as oil. Thus, 78 g of gasket paste was obtained.
The state stability, coatability, anti-drip property and sealability of the obtained gasket paste, and the compression deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation methods described above. Table 3 shows the results.
In Table 3, the results of Example 5 are also shown for comparison.

(Example 11)
As a surfactant containing 58% by weight of water, funnel oil (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is 89% by weight, and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 11% by weight. 78 g of gasket paste was obtained by stirring and mixing using a spatula.
The state stability and coatability of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 4 shows the results.

(Example 12)
As a surfactant containing 58% by weight of water, funnel oil (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is 80% by weight, and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 20% by weight. 78 g of gasket paste was obtained by stirring and mixing using a spatula.
The state stability and coatability of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 4 shows the results.

(Example 13)
As a surfactant containing 58% by weight of water, funnel oil (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is 69% by weight, and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 31% by weight. 78 g of gasket paste was obtained by stirring and mixing using a spatula.
The state stability, coatability, anti-drip property and sealability of the obtained gasket paste, and the compression deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation methods described above. Table 4 shows the results.

(Example 14)
As a surfactant containing 58% by weight of water, funnel oil (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is 50% by weight, and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 50% by weight. 78 g of gasket paste was obtained by stirring and mixing using a spatula.
The state stability, coatability and anti-drip property of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 4 shows the results.

(Example 15)
As a surfactant containing 58% by weight of water, funnel oil (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is 43% by weight, and calcined kaolin (manufactured by BASF Corporation, average particle size 1.4 μm) is 57% by weight. 78 g of gasket paste was obtained by stirring and mixing using a spatula.
The state stability and anti-drip property of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 4 shows the results.

(Example 16)
58% by weight of water, 7% by weight of polyoxyethylene alkyl ether (manufactured by Kao Corporation) as a surfactant, 24% by weight of powdered fluororesin (manufactured by Daikin Co., Ltd., average particle size 0.2 μm), 78 g of a gasket paste was obtained by stirring and mixing using a scoop so that calcined kaolin (manufactured by BASF Corporation, average particle size: 1.4 μm) was 11% by mass.
The state stability and coatability of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 5 shows the results.

(Example 17)
52% by weight of water, 6% by weight of polyoxyethylene alkyl ether (manufactured by Kao Corporation) as a surfactant, 22% by weight of powdered fluororesin (manufactured by Daikin Co., Ltd., average particle size 0.2 μm), 78 g of a gasket paste was obtained by stirring and mixing using a scoop so that calcined kaolin (manufactured by BASF Corporation, average particle size: 1.4 μm) was 20% by mass.
The state stability and coatability of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 5 shows the results.

(Example 18)
45% by weight of water, 5% by weight of polyoxyethylene alkyl ether (manufactured by Kao Corporation) as a surfactant, 19% by weight of powdered fluororesin (manufactured by Daikin Co., Ltd., average particle size 0.2 μm), 78 g of a gasket paste was obtained by stirring and mixing using a scoop so that calcined kaolin (manufactured by BASF Corporation, average particle size: 1.4 μm) was 31% by mass.
The state stability, coatability and sealability of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 5 shows the results.

(Example 19)
37% by weight of water, 4% by weight of polyoxyethylene alkyl ether (manufactured by Kao Corporation) as a surfactant, 16% by weight of powdered fluororesin (manufactured by Daikin Co., Ltd., average particle size 0.2 μm), 78 g of a gasket paste was obtained by stirring and mixing using a scoop so that calcined kaolin (manufactured by BASF Corporation, average particle size: 1.4 μm) was 43% by mass.
The state stability and coatability of the obtained gasket paste, and the compressive deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation method described above. Table 5 shows the results.

(Example 20)
32% by weight of water, 4% by weight of polyoxyethylene alkyl ether (manufactured by Kao Corporation) as a surfactant, 14% by weight of powdered fluororesin (manufactured by Daikin Co., Ltd., average particle size 0.2 μm), 78 g of a gasket paste was obtained by stirring and mixing with a scoop so that calcined kaolin (manufactured by BASF Corporation, average particle size: 1.4 μm) was 50% by mass.
The state stability of the obtained gasket paste and the compressive deformation resistance 1 of the gasket due to the obtained gasket paste were evaluated based on the evaluation method described above. Table 5 shows the results.

(Comparative Example 3)
Water is 64% by weight, polyoxyethylene alkyl ether (manufactured by Kao Corporation) as a surfactant is 8% by weight, and powdery fluororesin (manufactured by Daikin Corporation, average particle size 0.2 μm) is 28% by weight. 78 g of gasket paste was obtained by stirring and mixing using a medicine spoon.
The state stability, coatability, anti-drip property and sealability of the obtained gasket paste, and the compression deformation resistance 1 of the obtained gasket paste were evaluated based on the evaluation methods described above. Table 5 shows the results.

From the results shown in Tables 1 to 3, in Examples 1 to 10, since the gasket paste contains calcined clay, even though silicone oil, which is easy to slip as oil, is blended, In addition, the friction between the gasket and the mating member is increased to suppress compressive deformation (area increase). As a result, the compressive load is maintained and the sealing It can be seen that the leakage amount by the seal test is reduced due to the improvement of the performance.
The above seal test measures the amount of leakage at room temperature immediately after tightening the gasket, but under the conditions after heating that simulates actual use, the effect of suppressing compression deformation is exhibited, further reducing the amount of leakage. It goes without saying that it is effective.
In addition, from the results shown in Table 2, the gasket paste containing calcined clay has the same effect not only on joint sheets, but also on fluororesin gaskets with an extremely small coefficient of friction on the sheet surface, and has a similar effect on compressive deformation. (area increase) can be suppressed.

On the other hand, according to the results shown in Tables 1 and 3, in Comparative Examples 1 and 2, since the gasket paste does not contain sintered clay, the compressive deformation of the sealing surface tends to increase. (The area increase rate tends to increase.) As a result, the compressive load is not maintained, and the sealing properties deteriorate, resulting in an increase in the amount of leakage in the seal test.

From the results shown in Table 4, in Examples 11 to 15, even when the gasket paste contains calcined clay in water containing a surfactant instead of in oil, the calcined clay, water, and surfactant The bonding strength is increased and the stability of the gasket paste is improved. Furthermore, the friction between the gasket and the mating member is increased to suppress compressive deformation (area increase). It can be seen that the leakage rate by the seal test is reduced due to the improvement of
Further, from the results shown in Table 5, in Examples 16 to 20, even when the gasket paste further contained a powdery fluororesin, the friction between the gasket and the mating member was increased and the compression deformation ( area increase), and as a result, it can be seen that the compressive load is retained.

On the other hand, according to the results shown in Table 5, in Comparative Example 3, since the gasket paste does not contain calcined clay, the compressive deformation of the seal surface tends to increase (the area increase rate easy).

According to the present invention, it is possible to provide a gasket paste capable of exhibiting stable sealing performance over a long period of time while suppressing radial deformation of the gasket.

Claims (3)

A paste for coating a gasket, comprising calcined kaolin having an average particle size of 0.5 to 2 μm dispersed in oil or water containing a surfactant. 2. The gasket coating paste according to claim 1 , further comprising a powdery fluororesin dispersed therein. A gasket comprising a coating layer comprising the paste for coating a gasket according to claim 1 or 2 on its surface.