A sealing gasket for alkaline high temperature electrolytic cell and preparation method thereof

Abstract

The present invention provides a sealing gasket for an alkaline high-temperature electrolyzer and a preparation method thereof. The present invention first provides a sealing gasket for an alkaline high-temperature electrolyzer, wherein the material components thereof are measured by mass fraction, including: 150-180 parts of polytetrafluoroethylene (PTFE) resin, 0-80 parts of polyetheretherketone (PEEK), 5-18 parts of calcium carbonate, 10-50 parts of polyphenylene sulfide (PPS) short fibers, 0-20 parts of aluminum oxide, 0-10 parts of molybdenum disulfide, 1-5 parts of barium titanate, and 0-15 parts of graphite. The preparation method of the sealing gasket for an alkaline high-temperature electrolyzer comprises: at room temperature, stirring and mixing the material components according to a specific ratio to obtain a mixture, and pre-pressing the obtained mixture into a mold, then sintering it, and finally cooling it to obtain the mixture. The sealing gasket provided by the present invention meets the requirements of the high temperature working environment of the alkaline high temperature electrolytic cell up to 100-300°C, has the performance of high temperature resistance and strong alkali resistance, and the preparation method thereof is simple, existing equipment can be used, the production cost is low, and it is easy to promote in industry.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature alkaline electrolytic cells, and in particular relates to a sealing gasket for an alkaline high-temperature electrolytic cell and a preparation method thereof. Background Art

[0002] Polytetrafluoroethylene is resistant to strong acids and alkalis, high temperatures, and good insulation, and is widely used in flange sealing in the chemical industry. In particular, modified and enhanced polytetrafluoroethylene gaskets have been verified by long-term use in traditional alkaline water electrolyzers (working temperature below 95°C).

[0003] However, when used for a long time in a high-temperature alkaline electrolytic cell at 100-300°C, the existing gaskets cannot meet the requirements of temperature resistance, strength and fatigue resistance. At present, there is no report on the application of sealing gaskets for electrolytic cells that are both resistant to high temperature and strong alkali. Therefore, it is urgent to develop a gasket that can still meet the requirements of strength and fatigue resistance under high temperature conditions (100-300°C) so that high-efficiency high-temperature alkaline electrolytic cells can be widely put into industrial application.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a sealing gasket for an alkaline high-temperature electrolytic cell and a preparation method thereof, so as to solve the above-mentioned problems.

[0006] In order to achieve the above objectives, the present invention particularly adopts the following technical solutions:

[0007] The present invention provides a sealing gasket for an alkaline high-temperature electrolytic cell. The material components of the sealing gasket include, by mass fraction, 150-180 parts of polytetrafluoroethylene (PTFE) resin, 0-80 parts of polyetheretherketone (PEEK), 5-18 parts of calcium carbonate, 10-50 parts of polyphenylene sulfide (PPS) short fibers, 0-20 parts of aluminum oxide, 0-10 parts of molybdenum disulfide, 1-5 parts of barium titanate, and 0-15 parts of graphite.

[0008] Preferably, the aluminum oxide in the material component is 5-20 parts;

[0009] Further preferably, the polyetheretherketone is 40-60 parts;

[0010] More preferably, the polyphenylene sulfide (PPS) staple fibers are 30-50 parts.

[0011] The existing conventional sealing gaskets have insufficient temperature resistance and cannot meet the working conditions of alkaline high-temperature electrolytic cells up to 100-300°C. The gasket material components provided by this application include PPS short fibers, which are beneficial to increase the tensile strength of the gasket; the PEEK component improves the temperature resistance of the gasket; the addition of alumina can increase the hardness of the gasket. The three are matched in appropriate proportions to enable the gasket product to obtain better comprehensive performance, especially the fatigue resistance of the gasket under high temperature conditions. This application achieves the purpose of increasing the compressive strength and softening temperature of the gasket at the same time. Simply adding alumina to the material components will indeed increase the hardness of the gasket, but at the same time it will cause the gasket to be easily fractured and its softness will be relatively poor; only by adopting the specific material components and proportions of this application, through the synergistic effect between several important components, while improving its temperature resistance and strong alkali resistance, its pressure resistance and tensile strength are guaranteed.

[0012] The present invention also provides a method for preparing the sealing gasket for an alkaline high-temperature electrolytic cell, comprising:

[0013] At room temperature, the material components are mixed by differential stirring in a specific ratio to obtain a mixture, and the obtained mixture is pre-pressed into a shape, then sintered, and finally cooled to obtain the sealing gasket for the alkaline high-temperature electrolytic cell.

[0014] Preferably, the differential stirring and mixing comprises: first performing a first stirring and then performing a second stirring;

[0015] The first stirring speed is 500 r / min, and the time is 2-10 min; the second stirring speed is 1000-1500 r / min, and the time is 2-10 min.

[0016] More preferably, the first stirring time is 5-6 min; the second stirring time is 3 min.

[0017] Optionally, the pre-pressing pressure is 80-150 MPa, the temperature is 60-150°C, and the pre-pressing time is 10 minutes. Preferably, the pre-pressing pressure is 120 MPa, and the temperature is 100-120°C.

[0018] Preferably, the sintering comprises: transferring the pre-pressed product into a circular cylindrical sintering tool, placing each pre-pressed product in multiple layers with a stainless steel isolation ring, and then pushing the tool into a sintering furnace for heating;

[0019] Further preferably, the heating rate in the furnace is controlled at 80±5°C / min, the target temperature of the heating is 400-450°C, and the insulation time after heating is 2-3h.

[0020] Preferably, the cooling includes: first cooling naturally, then blowing the heating furnace with cold air, until the temperature in the furnace drops to 200°C or below, opening the heating furnace, pushing out the annular cylindrical tooling and continuing to blow air to cool down to 80°C or below, then stopping blowing and continuing to cool naturally to room temperature.

[0021] The present invention firstly changes the formula and ratio, combined with the adjustment of the preparation process, so that the prepared gasket has the performance of high temperature resistance and strong alkali resistance. First, the stirring and mixing needs to be carried out according to differential stirring, and the mixing time should not be too long to avoid the raw materials from generating heat, so that the polytetrafluoroethylene resin agglomerates. Once agglomerates, it is difficult to mix evenly with other materials, thereby affecting the strength and durability; secondly, the present application changes the molding process, especially the temperature is increased to 100-120°C during pre-pressing molding, and the pressure is increased to ensure the basic shape strength and performance of the preform; the preferred sintering temperature of the present application ensures the uniformity of the melt blending of the material, which helps to further improve the uniformity of the performance parameters of the gasket; finally, the present application adopts air cooling, and the cooling rate is gentle, which is conducive to the stability of the internal structure performance of the gasket.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Compared with the traditional formula, the present invention adds alumina, PPS, PEEK and other materials to the polytetrafluoroethylene resin and strictly controls the ratio to improve the heat resistance and softening temperature of the gasket while promoting it to have higher compressive strength to adapt to the special working environment of the alkaline high-temperature electrolytic cell.

[0024] The method for preparing a sealing gasket for an alkaline high-temperature electrolytic cell provided in the present application coordinates the precise control of the differential stirring rate and time, the regulation of the pre-pressing molding temperature and pressure, and the process adjustment of increasing the sintering temperature during the sintering process. It realizes the direct industrial production of the sealing gasket for an alkaline high-temperature electrolytic cell of the present application using the existing conventional low-temperature working gasket preparation equipment, without the need for special equipment or a separate production line, thus saving costs. The preparation method is simple, the process conditions are easy to control, and it is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is an appearance diagram of a test sample made of the sealing gasket material prepared in Example 4 before testing;

[0027] Figure 2 This is an appearance diagram of a test sample made of the sealing gasket material prepared in Example 5 before testing;

[0028] Figure 3 This is an appearance diagram of the test sample made of the sealing gasket material prepared in Examples 4 and 5 after testing;

[0029] Figure 4 This is the appearance of the test sample made of the sealing gasket material prepared in Comparative Example 1 before testing;

[0030] Figure 5 This is the appearance picture of the test sample made of the sealing gasket material prepared in Comparative Example 1 after testing. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] According to the preparation method provided by the present invention, this embodiment provides a sealing gasket for an alkaline high-temperature electrolytic cell, and the preparation method specifically comprises the following steps:

[0034] S1: prepare a mixture of 180 parts of polytetrafluoroethylene (PTFE) resin, 20 parts of polyetheretherketone (PEEK), 5 parts of calcium carbonate, 5 parts of molybdenum disulfide, 10 parts of polyphenylene sulfide PPS short fibers, 1 part of barium titanate, 5 parts of aluminum oxide, and 5 parts of graphite;

[0035] S2: Add the mixture of the above S1 materials according to the formula ratio into a mixer, stir and mix at room temperature, first mix at a low speed of 500r / min for 3min, and then mix at a high speed of 1200r / min for 3min; then pre-press and form, the pre-pressing pressure is 100MPa, the temperature is 100°C, and a pre-pressed product is obtained;

[0036] S3: The pre-pressed product obtained in S2 is moved to an annular cylindrical sintering fixture. A stainless steel isolation ring is used between each pre-pressed product. The pre-pressed products are placed in multiple layers. Then the fixture is pushed into the sintering furnace for heating. The heating rate is controlled at 80±5℃ / min. The sintering temperature is maintained at 400℃ for 2h. After sintering, the temperature is naturally cooled. Then, the heating furnace is purged with cold air until the temperature in the furnace drops to 200℃ or below. The heating furnace is opened, the annular cylindrical fixture is pushed out, and the air is continued to be blown to cool down to 80℃ or below. Then, the air is stopped and the temperature is continued to be naturally cooled to room temperature to obtain the product.

[0037] Example 2

[0038] According to the preparation method provided by the present invention, this embodiment provides a sealing gasket for an alkaline high-temperature electrolytic cell, and the preparation method specifically comprises the following steps:

[0039] S1: prepare a mixture of 170 parts of polytetrafluoroethylene (PTFE) resin, 30 parts of polyetheretherketone (PEEK), 6 parts of calcium carbonate, 6 parts of molybdenum disulfide, 20 parts of polyphenylene sulfide PPS short fibers, 2 parts of barium titanate, 6 parts of aluminum oxide, and 6 parts of graphite;

[0040] S2: Add the mixture of the above S1 materials according to the formula ratio into a mixer, stir and mix at room temperature, first mix at a low speed of 500r / min for 5min, and then mix at a high speed of 1200r / min for 3min; then pre-press and form, the pre-pressing pressure is 100MPa, the temperature is 110°C, and a pre-pressed product is obtained;

[0041] S3: The pre-pressed product obtained in S2 is moved into a circular cylindrical sintering fixture, and a stainless steel isolation ring is used between each pre-pressed product. The pre-pressed product is placed in multiple layers, and then the fixture is pushed into the sintering furnace for heating. The heating rate is controlled at 80±5℃ / min, and the sintering temperature is maintained at 400℃ for 2h. After sintering, the same cooling operation as in Example 1 is performed to obtain the product.

[0042] Example 3

[0043] According to the preparation method provided by the present invention, this embodiment provides a sealing gasket for an alkaline high-temperature electrolytic cell, and the preparation method specifically comprises the following steps:

[0044] S1: prepare a mixture of 160 parts of polytetrafluoroethylene (PTFE) resin, 40 parts of polyetheretherketone (PEEK), 10 parts of calcium carbonate, 30 parts of polyphenylene sulfide PPS short fibers, 5 parts of molybdenum disulfide, 5 parts of barium titanate, 10 parts of aluminum oxide, and 6 parts of graphite;

[0045] S2: Add the mixture of the above S1 materials according to the formula ratio into a mixer, stir and mix at room temperature, first mix at a low speed of 500r / min for 5min, and then mix at a high speed of 1200r / min for 3min; then pre-press and form, the pre-pressing pressure is 120MPa, the temperature is 120℃, and a pre-pressed product is obtained;

[0046] S3: The pre-pressed product obtained in S2 is moved into a circular cylindrical sintering fixture, and a stainless steel isolation ring is used between each pre-pressed product. The pre-pressed product is placed in multiple layers, and then the fixture is pushed into the sintering furnace for heating. The heating rate is controlled at 80±5℃ / min, and the sintering temperature is maintained at 410℃ for 2h. After sintering, the same cooling operation as in Example 1 is performed to obtain the product.

[0047] Example 4

[0048] According to the preparation method provided by the present invention, this embodiment provides a sealing gasket for an alkaline high-temperature electrolytic cell, and the preparation method specifically comprises the following steps:

[0049] S1: Prepare a mixture by taking 150 parts of polytetrafluoroethylene (PTFE) resin, 60 parts of polyetheretherketone (PEEK), 18 parts of calcium carbonate, 30 parts of polyphenylene sulfide PPS short fibers, 5 parts of molybdenum disulfide, 5 parts of barium titanate, 15 parts of aluminum oxide, and 6 parts of graphite;

[0050] S2: Add the mixture of the above S1 materials according to the formula ratio into a mixer, stir and mix at room temperature, first mix at a low speed of 500r / min for 5min, and then mix at a high speed of 1200r / min for 3min; then pre-press and form, the pre-pressing pressure is 130MPa, the temperature is 130°C, and a pre-pressed product is obtained;

[0051] S3: The pre-pressed product obtained in S2 is moved to a circular cylindrical sintering fixture. A stainless steel isolation ring is used between each pre-pressed product. The pre-pressed product is placed in multiple layers. The fixture is then pushed into the sintering furnace for heating. The heating rate is controlled at 80±5℃ / min. The sintering temperature is maintained at 420℃ for 2.5h. After sintering, it is cooled.

[0052] Example 5

[0053] According to the preparation method provided by the present invention, this embodiment provides a sealing gasket for an alkaline high-temperature electrolytic cell, and the preparation method specifically comprises the following steps:

[0054] S1: Prepare a mixture by taking 180 parts of polytetrafluoroethylene (PTFE) resin, 60 parts of polyetheretherketone (PEEK), 10 parts of calcium carbonate, 40 parts of polyphenylene sulfide PPS short fibers, 5 parts of molybdenum disulfide, 5 parts of barium titanate, 15 parts of aluminum oxide, and 12 parts of graphite;

[0055] S2: Add the mixture of the above S1 materials according to the formula ratio into a mixer, stir and mix at room temperature, first mix at a low speed of 500r / min for 5min, and then mix at a high speed of 1200r / min for 3min; then pre-press and form, the pre-pressing pressure is 145MPa, the temperature is 150°C, and a pre-pressed product is obtained;

[0056] S3: The pre-pressed product obtained in S2 is moved to a circular cylindrical sintering fixture. A stainless steel isolation ring is used between each pre-pressed product. The pre-pressed product is placed in multiple layers. The fixture is then pushed into the sintering furnace for heating. The heating rate is controlled at 80±5℃ / min. The sintering temperature is maintained at 450℃ for 2.5h. After sintering, it is cooled.

[0057] Comparative Example 1

[0058] The difference from Example 1 is that in the preparation step of this comparative sample, S1 does not include polyphenylene sulfide PPS short fibers, and other conditions are the same as those in Example 1.

[0059] Comparative Example 2

[0060] The difference from Example 2 is that PEEK is not added when preparing the mixed material in step S1, and the rest is the same as Example 2.

[0061] Comparative Example 3

[0062] The difference from Example 3 is that 100 parts of aluminum oxide are added when preparing the mixed material in step S1. Other conditions are the same.

[0063] Comparative Example 4

[0064] The difference from Example 4 is that the S2 preforming temperature is room temperature without heating, and all other conditions are the same as Example 4.

[0065] Comparative Example 5

[0066] The difference from Example 5 is that the stirring and mixing time in step S2 is different. This comparative example is first mixed at a low speed of 500 r / min for 30 min, and then mixed at a high speed of 1200 r / min for 30 min.

[0067] The performance test data of the gasket products provided in the examples and comparative examples of the present application are shown in Table 1 below:

[0068] Table 1 Gasket product performance test data provided by the embodiments and comparative examples

[0069] project Tensile strength MPa Compressive strength MPa <![CDATA[Loss on ignition g·m -2 > Softening temperature℃ Example 1 32 62 0.63 195 Example 2 34 65 0.48 216 Example 3 38 68 0.22 276 Example 4 41 79 0.16 313 Example 5 46 90 0.12 315 Comparative Example 1 21 42 1.50 112 Comparative Example 2 22 48 1.21 102 Comparative Example 3 20 68 5.22 290 Comparative Example 4 38 55 1.93 190 Comparative Example 5 32 68 1.82 212

[0070] It can be seen from Table 1 that the gasket provided in the embodiment of the present application has significantly improved tensile strength and compressive strength compared with the control example, lower alkali loss and higher softening temperature, indicating that under high temperature and strong alkali conditions, the comprehensive performance of the sealing gasket provided in the present application, such as tensile and compressive strength, working stability, alkali resistance and high temperature resistance, is superior.

[0071] The sealing gasket material prepared in Example 4 and Example 5 of the present invention was used to make a test sample with an inner diameter of 210 mm and an outer diameter of 230 mm, and a practical application test was carried out on an electrolytic cell. The equipment sealing air pressure was set to 2.5 MPa, the axial compression force on the gasket was 50 MPa, the radial pressure was 2.5 MPa, the sealing medium was 30% NaOH lye, the working temperature was 130-210°C, and the current density was 8000 A / m 2 Under working conditions, continuous working for 1000 hours, respectively Figure 1-3 As shown, Figure 1 This is the appearance of the test sample made of the sealing gasket material prepared in Example 4 before testing. Figure 2 This is the appearance of the test sample made of the sealing gasket material prepared in Example 5 before testing. Figure 3 This is the appearance of the test sample made of the sealing gasket material prepared in Examples 4 and 5 after testing, where Figure 3 (a) corresponds to Example 4, Figure 3 (b) Corresponding to Example 5; Figure 1-Figure 3 It can be seen that the samples provided in Examples 4-5 of the present invention did not soften, deform, or leak, which means that the products provided by the present invention can operate stably for a long time on industrial equipment.

[0072] At the same time, the sealing gasket material of comparative example 1 was used to make a test product in the same way, and an actual application test was carried out on the electrolytic cell. The equipment sealing pressure was set to 2.5 MPa, the axial compression force on the gasket was 50 MPa, the radial pressure was 2.5 MPa, the sealing medium was 30% NaOH lye, the working temperature was 100-115°C, and the current density was 8000 A / m 2 Under working conditions, after running for 100 hours, if Figure 4-5 As shown, Figure 4 This is the appearance of the test product made of the sealing gasket material prepared in Comparative Example 1 before testing. Figure 5 This is the appearance of the test product made of the sealing gasket material prepared in Comparative Example 1 after testing, wherein: Figure 5 The middle figure is a complete appearance picture of the test product made of the sealing gasket material prepared in Comparative Example 1 after testing. Figure 5 The left picture is an enlarged view of the left side of the middle picture. Figure 5The right picture is an enlarged view of the partial appearance on the right side of the middle figure; by comparison, it can be seen that the air channel and liquid channel holes of the gasket product provided in Comparative Example 1 are obviously deformed.

[0073] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A sealing gasket for an alkaline high temperature electrolytic cell, characterized in that: The material components of the sealing gasket include, by weight: 150-180 parts of polytetrafluoroethylene (PTFE) resin, 0-80 parts of polyetheretherketone (PEEK), 5-18 parts of calcium carbonate, 10-50 parts of polyphenylene sulfide (PPS) short fibers, 5-20 parts of aluminum oxide, 0-10 parts of molybdenum disulfide, 1-5 parts of barium titanate, and 0-15 parts of graphite; The preparation method of the sealing gasket comprises: at room temperature, stirring and mixing the material components according to a specific ratio to obtain a mixture, pre-pressing the obtained mixture into a shape, then sintering, and finally cooling to obtain the sealing gasket for the alkaline high-temperature electrolytic cell; The stirring and mixing is differential stirring and mixing; the differential stirring and mixing includes: first stirring and then second stirring; wherein the speed of the first stirring is 500r / min and the time is 2-10min; the speed of the second stirring is 1000-1500r / min and the time is 2-10min; The pre-pressing pressure is 80-150 MPa, the temperature is 60-150° C., and the pre-pressing time is 10 min.

2. The sealing gasket according to claim 1, characterized in that: The polyetheretherketone is 40-60 parts; The polyphenylene sulfide (PPS) short fibers are present in an amount of 30-50 parts.

3. The sealing gasket according to claim 1, characterized in that: The first stirring time is 5-6 min; The second stirring time was 3 min.

4. The sealing gasket according to claim 1, characterized in that: The pre-pressing pressure is 120 MPa and the temperature is 100-120°C.

5. The sealing gasket according to claim 1, characterized in that: The sintering comprises: transferring the pre-pressed product into a circular cylindrical sintering tool, placing each pre-pressed product in multiple layers with a stainless steel isolation ring, and then pushing the tool into a sintering furnace to heat it; The heating rate in the furnace is controlled at 80±5°C / min, the target temperature of the heating is 400-450°C, and the insulation time after heating is 2-3h.

6. The sealing gasket according to claim 1, characterized in that: The cooling includes: firstly cooling naturally, then blowing the heating furnace with cold air, until the temperature in the furnace drops to 200°C or below, opening the heating furnace, pushing out the circular cylindrical tooling and continuing to blow air to cool down to 80°C or below, then stopping blowing and continuing to cool naturally to room temperature.

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