A modified ceramic fiber filled metal coated gasket and preparation method thereof

Abstract

The present invention discloses a method for preparing a metal-coated gasket filled with modified ceramic fibers, which comprises the following steps: S1: pre-treating the ceramic fibers under the action of an acidic ionic liquid and an oxidant; S2: dispersing the ceramic fibers in a reactive surfactant, adding a mixed solution of acrylate monomers, vinyl cage polysilsesquioxane, a photoinitiator and anhydrous ethanol, UV curing, and heating the reaction to obtain the modified ceramic fibers; S3: mixing the modified ceramic fibers with expanded graphite, tannic acid, methyl acrylate, calcium carbonate whiskers, polyvinylidene fluoride and expanded vermiculite to obtain a filler; S4: laying the modified ceramic fibers on a metal sheet and processing the metal-coated flat gasket. The metal-coated gasket prepared by the present invention has good comprehensive mechanical properties, not only has excellent heat and pressure resistance, but also has good stability and resilience, and can meet the requirements of long-term stability and cyclic sealing under harsh working conditions.

Description

Technical Field

[0001] The invention relates to the technical field of sealing gaskets, and in particular to a metal-clad gasket filled with modified ceramic fibers and a preparation method thereof. Background Art

[0002] Metal-coated gaskets refer to composite gaskets with non-metallic materials (flexible graphite, asbestos rubber sheet, ceramic fiber) etc. inside and metal sheets coated on the outside by a specific cold working process. According to the gasket cross section, they are usually divided into two types: flat coating and corrugated coating. They are the most traditional type of tight-fitting gaskets, suitable for heat exchangers, pressure vessels, pumps, valves and flange surface seals. The advantages of metal-coated gaskets are high strength, not easy to break, firm and strong, but limited resilience, requiring the flange surface to be flat and the tightening force to be very high to achieve good results. In addition, in the prior art, ceramic fiber-filled metal-coated gaskets have certain temperature resistance and strengthening effects. However, for large-diameter gaskets, since a number of holes for bolt tightening are opened in the annular array, the ceramic fiber-filled transition area between the gasket hole and the inner and outer edges is greatly deformed and has poor resilience. In severe cases, the ceramic fiber breaks, affecting the secondary use of the gasket. Summary of the invention

[0003] In view of the above shortcomings of the prior art, the present invention provides a metal-coated gasket filled with modified ceramic fibers to solve the problem that the existing metal-coated gaskets cannot take into account the performance requirements of high temperature and high pressure resistance, stability, and resilience, and thus cannot meet the long-term continuous stability and secondary cycle sealing requirements under harsh conditions.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A method for preparing a metal-clad gasket filled with modified ceramic fibers, the method comprising the following steps:

[0006] S1: Place the ceramic fiber in a reactor, add an acidic ionic liquid and an oxidant to the reactor, immerse for 15 to 25 minutes at a water bath temperature of 55 to 65°C for pretreatment, and then rinse with deionized water and tetrahydrofuran until neutral; the present invention swells the ceramic fiber with an acidic ionic liquid, and then further softens the ceramic fiber under the oxidizing action of the oxidant, and combines the strong dissolving ability of the ionic liquid to hydrophilically modify and ionize the surface and interior of the ceramic fiber. The ceramic fiber treated by step S1 is easier to disperse in the reactive surfactant of step S2, and can then efficiently perform modification reaction treatment on the surface and interior of the fiber.

[0007] S2: The ceramic fibers treated in step S1 are uniformly dispersed in a reactive surfactant, and a mixed solution of acrylate monomer, vinyl cage polysilsesquioxane, photoinitiator and anhydrous ethanol is added. After UV curing for 0.5 to 1 hour, the temperature is raised to 60 to 90°C to obtain modified ceramic fibers. The present application performs organic modification of ceramic fibers by chemical bonding. On the one hand, the reactive surfactant cross-links with the acrylate monomer and the vinyl cage polysilsesquioxane under the action of the photoinitiator. The introduction of acrylate improves the binding force of the ceramic fibers in the metal-coated gasket, and makes it easy to disperse in the raw materials in step S3. On the other hand, the organic-inorganic hybrid material with a cage-type nanostructure is introduced through the vinyl cage polysilsesquioxane, thereby improving the high temperature and high pressure resistance of the metal-coated gasket. Furthermore, through the rapid volatilization of anhydrous ethanol, the UV-cured organic modified ceramic fibers are micro-foamed, which promotes the metal-coated gasket to have a certain resilience effect; the ceramic fibers treated by steps S1 and S2 are effectively prevented from breaking, thereby enhancing the secondary use effect of the gasket.

[0008] S3: 100 parts by weight of expanded graphite, 3-7 parts of tannic acid, 3.5-5.5 parts of methyl acrylate, 0.5-1.5 parts of calcium carbonate whiskers, 1.5-5 parts of polyvinylidene fluoride, 4-9 parts of expanded vermiculite and 7-12 parts of modified ceramic fibers obtained in step S2 are weighed and mixed evenly by high-speed mechanical stirring to obtain a filler; the gasket filler of the present application is mainly composed of expanded graphite, and various comprehensive properties of the metal-coated flat gasket are further improved by reasonably adding various additives.

[0009] S4: placing the punched, flanging and roughened metal sheet in a mold, and then laying the filler in step S3 on the metal sheet, and performing sheeting, rolling and hemming operations to obtain the metal-coated flat gasket.

[0010] Preferably, the acidic ionic liquid is at least one of 1-sulfonic acid butyl-3-methylimidazolium hydrogen sulfate, 1-sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate, 1-sulfonic acid hexyl-3-methylimidazolium hydrogen sulfate or 1-sulfonic acid hexyl-3-methylimidazolium trifluoromethanesulfonate. The present application prefers acidic ionic liquids, which are more conducive to the continuous oxidation of the oxidant.

[0011] Preferably, the oxidant is at least one of potassium permanganate, peracetic acid and hydrogen peroxide.

[0012] Preferably, the reactive surfactant is prepared by substitution reaction of olefin pyridine and brominated long-chain alkane in a molar ratio of 1:1. The reactive surfactant of the present application is obtained by substitution reaction of brominated long-chain alkane with nitrogen atoms in olefin pyridine to obtain olefin pyridine salt grafted with long-chain alkane. On the one hand, the ionized reactive surfactant promotes the uniform dispersion effect of ceramic fibers. On the other hand, by introducing olefin groups, it can undergo addition cross-linking reaction with other substances with unsaturated double bonds, so that the ceramic fibers are chemically modified on the surface.

[0013] Preferably, the olefinyl pyridine is at least one of 4-vinyl pyridine, 4-(1-penten-3-yl) pyridine, 2,6-dimethyl-4-vinyl pyridine, and 4-[(allyloxy)methyl] pyridine.

[0014] Preferably, the brominated long-chain alkane is at least one of 1-bromooctane, 2-bromooctane, 1-bromo-2-methyl-octane and 1-bromo-7-methyloctane.

[0015] Preferably, the acrylic acid ester monomer is at least one of methyl methacrylate, butyl acrylate and ethyl acrylate.

[0016] Preferably, the photoinitiator is at least one of 2-hydroxy-2-methyl-1-phenylpropanone-1, 2-hydroxy-2-methyl-1-p-isopropylphenylpropanone-1, 4-hydroxybenzophenone and 1-hydroxy-cyclohexylphenylketone.

[0017] Another aspect of the present invention is to provide a modified ceramic fiber filled metal sheathed gasket, wherein the metal sheathed gasket is prepared by the above-mentioned method for preparing the modified ceramic fiber filled metal sheathed gasket.

[0018] Beneficial effects of the present invention:

[0019] The metal-clad gasket prepared by the present invention has good comprehensive mechanical properties, not only has excellent temperature and pressure resistance, but also has good stability and resilience, and can meet the long-term continuous stability and secondary cycle sealing requirements under harsh working conditions. DETAILED DESCRIPTION

[0020] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0021] Example 1

[0022] The method for preparing the metal-clad gasket filled with modified ceramic fibers in this embodiment comprises the following steps:

[0023] S1: placing ceramic fiber in a reactor, adding 1-sulfonic acid butyl-3-methylimidazole hydrogen sulfate and potassium permanganate to the reactor, immersing for 15 minutes in a water bath at 60° C. for pretreatment, and then rinsing with deionized water and tetrahydrofuran until neutral; the mass ratio of the ceramic fiber to the acidic ionic liquid and the oxidant is 100:50:5.5;

[0024] S2: 30 parts by weight of the ceramic fibers treated in step S1 are uniformly dispersed in 25 parts by weight of a reactive surfactant, and a mixed solution of methyl methacrylate, vinyl cage polysilsesquioxane, 2-hydroxy-2-methyl-1-phenylpropanone-1 and anhydrous ethanol is added, and after UV curing for 0.5 hours, the temperature is raised to 70° C. to react to obtain modified ceramic fibers; the molar ratio of methyl methacrylate, vinyl cage polysilsesquioxane and reactive surfactant is 5:1:10; the mass ratio of 2-hydroxy-2-methyl-1-phenylpropanone-1 in the mixed solution is 0.5%, and the mass concentration of methyl methacrylate in the mixed solution is 15%;

[0025] S3: weigh 100 parts of expanded graphite, 3 parts of tannic acid, 3.5 parts of methyl acrylate, 0.5 parts of calcium carbonate whisker, 1.5 parts of polyvinylidene fluoride, 4 parts of expanded vermiculite and 7 parts of modified ceramic fiber obtained in step S2, and mix them evenly with high-speed mechanical stirring to obtain a filler;

[0026] S4: placing the punched, flanging and roughened metal sheet in a mold, and then laying the filler in step S3 on the metal sheet, and performing sheeting, rolling and hemming operations to obtain the metal-coated flat gasket.

[0027] The reactive surfactant is prepared by substitution reaction of 4-vinylpyridine and 1-bromooctane in a molar ratio of 1:1.

[0028] Example 2

[0029] The method for preparing the metal-clad gasket filled with modified ceramic fibers in this embodiment comprises the following steps:

[0030] S1: placing ceramic fiber in a reactor, adding 1-sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate and peracetic acid to the reactor, immersing for 25 minutes in a water bath at 65° C. for pretreatment, and then rinsing with deionized water and tetrahydrofuran until neutral; the mass ratio of the ceramic fiber to the acidic ionic liquid and the oxidant is 100:55:6.5;

[0031] S2: 30 parts by weight of the ceramic fiber treated in step S1 are uniformly dispersed in 25 parts by weight of a reactive surfactant, and a mixed solution of butyl acrylate, vinyl cage polysilsesquioxane, 4-hydroxybenzophenone and anhydrous ethanol is added, and after UV curing for 1 hour, the temperature is raised to 70°C to react to obtain modified ceramic fibers; the molar ratio of butyl acrylate, vinyl cage polysilsesquioxane and reactive surfactant is 6:1.5:10; the mass ratio of 4-hydroxybenzophenone in the mixed solution is 0.5%, and the mass concentration of butyl acrylate in the mixed solution is 17%;

[0032] S3: weigh 100 parts of expanded graphite, 5 parts of tannic acid, 4.5 parts of methyl acrylate, 1 part of calcium carbonate whisker, 3.5 parts of polyvinylidene fluoride, 5 parts of expanded vermiculite and 10 parts of the modified ceramic fiber obtained in step S2, and mix them evenly with high-speed mechanical stirring to obtain a filler;

[0033] S4: placing the punched, flanging and roughened metal sheet in a mold, and then laying the filler in step S3 on the metal sheet, and performing sheeting, rolling and hemming operations to obtain the metal-coated flat gasket.

[0034] The reactive surfactant is prepared by substitution reaction of 2,6-dimethyl-4-vinylpyridine, 4-[(allyloxy)methyl]pyridine and 1-bromo-2-methyl-octane in a molar ratio of 1:1.

[0035] Example 3

[0036] The method for preparing the metal-clad gasket filled with modified ceramic fibers in this embodiment comprises the following steps:

[0037] S1: placing ceramic fiber in a reaction kettle, adding 1-hexylsulfonate-3-methylimidazole hydrogen sulfate and hydrogen peroxide to the reaction kettle, immersing for 25 minutes at a water bath temperature of 65° C. for pretreatment, and then rinsing with deionized water and tetrahydrofuran until neutral; the mass ratio of the ceramic fiber to the acidic ionic liquid and the oxidant is 100:60:7.5;

[0038] S2: 30 parts by weight of the ceramic fibers treated in step S1 are uniformly dispersed in 25 parts by weight of a reactive surfactant, and a mixed solution of ethyl acrylate, vinyl cage polysilsesquioxane, 1-hydroxy-cyclohexyl phenyl ketone and anhydrous ethanol is added, and after UV curing for 1 hour, the temperature is raised to 90° C. to react to obtain modified ceramic fibers; the molar ratio of ethyl acrylate, vinyl cage polysilsesquioxane and reactive surfactant is 7:2:10; the mass ratio of 1-hydroxy-cyclohexyl phenyl ketone in the mixed solution is 0.5%, and the mass concentration of ethyl acrylate in the mixed solution is 20%;

[0039] S3: weigh 100 parts of expanded graphite, 7 parts of tannic acid, 5.5 parts of methyl acrylate, 1.5 parts of calcium carbonate whiskers, 5 parts of polyvinylidene fluoride, 9 parts of expanded vermiculite and 12 parts of the modified ceramic fiber obtained in step S2, and mix them evenly with high-speed mechanical stirring to obtain a filler;

[0040] S4: placing the punched, flanging and roughened metal sheet in a mold, and then laying the filler in step S3 on the metal sheet, and performing sheeting, rolling and hemming operations to obtain the metal-coated flat gasket.

[0041] The reactive surfactant is prepared by substitution reaction of 4-[(allyloxy)methyl]pyridine and 1-bromo-7-methyloctane in a molar ratio of 1:1.

[0042] Comparative Example 1

[0043] The raw material composition and preparation steps of the preparation method of the metal-coated gasket filled with modified ceramic fibers in this comparative example are basically the same as those in Example 1, except that, in the preparation method of the metal-coated gasket in this comparative example, the ceramic fibers are not treated in step S1.

[0044] Comparative Example 2

[0045] The raw material composition and preparation steps of the preparation method of the metal-coated gasket filled with modified ceramic fibers in this comparative example are basically the same as those in Example 1, except that, in the preparation method of the metal-coated gasket in this comparative example, no vinyl cage-type polysilsesquioxane raw material is added to participate in the reaction in step S2.

[0046] Comparative Example 3

[0047] The raw material composition and preparation steps of the metal-coated gasket filled with modified ceramic fibers in this comparative example are basically the same as those in Example 1, except that, in the preparation method of the metal-coated gasket in this comparative example, the raw material 4-[(allyloxy)methyl]pyridine in the preparation method of the reactive surfactant in step S2 is replaced by 4-ethoxy-3-methylpyridine.

[0048] The performance of the metal-coated gaskets filled with modified ceramic fibers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested, and the performance results are shown in Table 1:

[0049] Antioxidation performance test: The metal-coated gaskets prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were placed in a muffle furnace for high-temperature calcination, and the oxidation weight loss rate of the metal-coated gaskets was measured at 800° C. for 8 h to evaluate their antioxidation performance;

[0050] Sealing performance test: Under the conditions of medium pressure of 5MPa and metal sheathed gasket specific pressure of 30MPa, the rebound rate and compression rate are tested to evaluate its compression rebound performance, and the sealing performance is evaluated by testing the leakage rate of the metal sheathed gasket.

[0051] Cyclic performance test: keep the sample at a medium pressure of 5MPa and a metal-coated gasket specific pressure of 30MPa for 20 hours, remove it and let it stand for 4 hours. This is considered a cycle. After 7 cycles, test its leakage rate again to evaluate its cyclic performance.

[0052] Table 1

[0053] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Oxidation weight loss rate, % 11.5 11.1 10.7 13.4 12.7 15.1 Change rate of tensile strength, % 8.11 8.26 8.18 7.21 6.83 7.23 Rebound rate, % 16.3 16.8 15.9 14.1 12.3 12.5 Compression ratio, % 43.5 45.1 44.8 37.4 38.5 39.2 Leakage rate, mL / min 0.12 0.11 0.13 0.17 0.17 0.18 Cycle performance 0.12 0.12 0.13 0.19 0.21 0.21

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A method for preparing a metal-clad gasket filled with modified ceramic fibers, characterized in that: The preparation method comprises the following steps: S1: placing the ceramic fiber in a reactor, adding an acidic ionic liquid and an oxidant into the reactor, immersing the ceramic fiber in a water bath at 55 to 65° C. for 15 to 25 minutes for pretreatment, and then rinsing the ceramic fiber with deionized water and tetrahydrofuran until the fiber becomes neutral; S2: uniformly dispersing the ceramic fibers treated in step S1 in a reactive surfactant, adding a mixed solution of acrylate monomer, vinyl cage polysilsesquioxane, photoinitiator and anhydrous ethanol, UV curing for 0.5 to 1 hour, heating to 60 to 90° C., and reacting to obtain modified ceramic fibers; S3: weigh 100 parts of expanded graphite, 3-7 parts of tannic acid, 3.5-5.5 parts of methyl acrylate, 0.5-1.5 parts of calcium carbonate whiskers, 1.5-5 parts of polyvinylidene fluoride, 4-9 parts of expanded vermiculite and 7-12 parts of the modified ceramic fiber obtained in step S2, and mix them evenly with a high-speed mechanical stirring to obtain a filler; S4: placing the punched, flanging and roughened metal sheet in a mold, and then laying the filler in step S3 on the metal sheet, and performing sheeting, rolling and hemming operations to obtain the metal-coated flat gasket.

2. The method for preparing the metal-clad gasket filled with modified ceramic fibers according to claim 1, characterized in that: The acidic ionic liquid is at least one of 1-sulfonic acid butyl-3-methylimidazolium hydrogen sulfate, 1-sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate, 1-sulfonic acid hexyl-3-methylimidazolium hydrogen sulfate or 1-sulfonic acid hexyl-3-methylimidazolium trifluoromethanesulfonate.

3. The method for preparing the metal-clad gasket filled with modified ceramic fibers according to claim 1, characterized in that: The oxidant is at least one of potassium permanganate, peracetic acid and hydrogen peroxide.

4. The method for preparing the modified ceramic fiber filled metal clad gasket according to claim 1, characterized in that: The reactive surfactant is prepared by substitution reaction of olefin pyridine and brominated long-chain alkane in a molar ratio of 1:

1.

5. The method for preparing the metal-clad gasket filled with modified ceramic fibers as claimed in claim 4, characterized in that: The olefin pyridine is at least one of 4-vinyl pyridine, 4-(1-penten-3-yl) pyridine, 2,6-dimethyl-4-vinyl pyridine, and 4-[(allyloxy)methyl] pyridine.

6. The method for preparing the metal-clad gasket filled with modified ceramic fibers as claimed in claim 4, characterized in that: The brominated long-chain alkane is at least one of 1-bromooctane, 2-bromooctane, 1-bromo-2-methyl-octane and 1-bromo-7-methyloctane.

7. The method for preparing the modified ceramic fiber filled metal clad gasket according to claim 1, characterized in that: The acrylic acid ester monomer is at least one of methyl methacrylate, butyl acrylate and ethyl acrylate.

8. The method for preparing the modified ceramic fiber filled metal clad gasket according to claim 1, characterized in that: The photoinitiator is at least one of 2-hydroxy-2-methyl-1-phenylpropanone-1, 2-hydroxy-2-methyl-1-p-isopropylphenylpropanone-1, 4-hydroxybenzophenone and 1-hydroxy-cyclohexylphenylketone.

9. A metal-clad gasket filled with modified ceramic fibers, characterized in that: The metal-clad gasket is prepared by the method for preparing a metal-clad gasket filled with modified ceramic fibers according to any one of claims 1 to 8.