A new special seal and its formula and preparation method

Abstract

The application discloses a novel special sealing element and a formula and a preparation method thereof. The cross-sectional shape of the sealing element is mushroom-shaped and connected by an arc-shaped part and a trapezoidal part connected with the bottom end of the arc-shaped part. The two sides of the connecting part of the arc-shaped part and the trapezoidal part are respectively in the shape of an inclined plane. An oval hole is arranged in the middle of the connecting part of the arc-shaped part and the trapezoidal part. A rectangular opening is arranged in the bottom end of the trapezoidal part. The sealing element has good elastic compression performance. After being fixed in a sealing groove, the sealing element can be closely combined with the sealing groove, the sealing element can be prevented from falling off, and the sealing performance is excellent. The formula of the novel special sealing element comprises silica gel mixed rubber and double D 24 vulcanizing agents, and does not need to add anti-scorching agents, vulcanizing accelerators and activators. The glue strip is prepared by adopting an extrusion molding process and a two-stage vulcanization process. The glue strip is cut and spliced and vulcanized to form the novel special sealing element. The novel special sealing element is suitable for high-temperature environments, the maximum environmental humidity can reach 100%, and has the properties of sodium fire resistance, sodium gas aerosol resistance, radiation resistance and high-temperature and high-pressure resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to a new type of special seal and its formula and preparation method. BACKGROUND

[0002] In the case of sodium fire accident, the process room will appear high temperature, high pressure, radioactive sodium aerosol spread and other phenomena, the highest environmental humidity can be up to 100%, the gas medium environment can contain salt air, sodium peroxide aerosol, hot sodium, water vapor and so on. In order to maintain the integrity and sealing of the overall structure of each process room, the seal is needed for each device and the space between the devices. In addition to having excellent sealing performance, the seal also needs to have the performance of sodium fire resistance, sodium aerosol resistance, radiation resistance, high temperature and high pressure resistance. However, the current seal can rarely meet all these performance requirements, and if the seal falls off from the sealing groove, it will have serious consequences. SUMMARY

[0003] The purpose of the present application is to overcome the defects of the prior art, and to provide a new type of special seal with good elastic compression performance, which can be tightly fitted with the sealing groove after being fixed in the sealing groove, can prevent the seal from falling off, and has excellent sealing performance.

[0004] Another purpose of the present application is to provide a new type of special seal formula and preparation method, and the prepared seal has the performance of sodium fire resistance, sodium aerosol resistance, radiation resistance, high temperature and high pressure resistance.

[0005] A technical solution to achieve the above purpose is: a new type of special seal, the cross-sectional shape of the seal is mushroom-shaped, which is connected by an arc-shaped part and a trapezoidal part connected to the bottom end of the arc-shaped part, and the connection between the arc-shaped part and the trapezoidal part is in the form of a slope on both sides, and the inclination angle of the slope is 2°-10°.

[0006] An oval hole is formed in the middle of the connection between the arc-shaped part and the trapezoidal part, and the ratio of the short axis to the long axis of the oval hole is 1:2.

[0007] A rectangular opening is formed at the bottom end of the trapezoidal part, and the ratio of the width to the height of the rectangular opening is 3:2.

[0008] The angles of the two bottom angles of the lower base of the trapezoidal part are 70°-80° respectively.

[0009] The present application also provides a formula of the above-mentioned new type of special seal, which comprises a silica gel compound and a double-dioxide vulcanizing agent, without adding anti-scorching agent, vulcanization accelerator and activator.

[0010] The minimum viscosity of the silica rubber compound is 2.2-6, the scorch time is 0.8-1.8 minutes, the tensile strength is greater than 1100 PSI, the elongation at break is greater than 400%, the compression set is less than 55%, the plasticity is 330-440, the Shore A hardness is 50-70, and the specific gravity is 1-1.3.

[0011] The application also provides a preparation method of the novel special sealing element, comprising the following steps:

[0012] S1, mixing step: the silica rubber compound and the double D 24 curing agent are put into a mixing machine for mixing, the temperature of the rubber compound is controlled at 26±2℃ during mixing, and the mixing is performed for 10 minutes, and the mixing uniformity is visually inspected;

[0013] S2, extrusion step: the mixed rubber compound is put into an extruder for extrusion to obtain a rubber strip, the extrusion temperature is controlled at 26±2℃, and the extruder outlet is provided with a mold with the same tolerance as the cross-sectional size of the product for extrusion;

[0014] S3, parking step: the extruded rubber strip is parked, the parking temperature is controlled at 26±2℃, and the parking time is controlled within 30 minutes;

[0015] S4, vulcanization step: the parked rubber strip is placed on a horizontal conveying belt, and is first subjected to hot air vulcanization in a high-temperature box, the vulcanization temperature of the high-temperature box is controlled at 170±5℃, and the vulcanization lasts for 20 minutes; the rubber strip directly enters a second high-temperature box for hot air vulcanization along the horizontal conveying belt, the vulcanization temperature of the second high-temperature box is controlled at 200±5℃, and the vulcanization lasts for 4 hours; and the vulcanized rubber strip is wound, and the length of each roll is not greater than 100 m;

[0016] S5, joint step: the rubber strip with a required length is cut, then the two ends of the rubber strip are butted, a gypsum rod is arranged in the joint, the joint is put into a mold pressing device, glue is injected, and the joint is vulcanized and formed by using a local vulcanization process, the gypsum rod is broken after the joint is formed, the integrity of the joint is ensured, and the formed novel special sealing element is obtained.

[0017] The novel special sealing element, the formula and the preparation method thereof have the advantages that the elastic compression performance is good, the sealing element can be tightly combined with a sealing groove after being fixed in the sealing groove, the sealing element can be prevented from falling off, the sealing performance is excellent, the novel special sealing element is suitable for a high-temperature environment, the maximum environmental humidity can be up to 100%, the gas medium environment can contain salt air, peroxide sodium aerosol, hot sodium, water vapor and the like, the novel special sealing element can withstand negative pressure or positive pressure, can resist mechanical aging, and can resist irradiation. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a cross-sectional view of a novel special sealing element according to the application;

[0019] Figure 2The installation diagram of the new special sealing element. DETAILED DESCRIPTION

[0020] In order to make the skilled in the art better understand the technical solutions of the present application, the specific embodiments thereof will be described in detail below with reference to the accompanying drawings:

[0021] Please refer to Figure 1 and Figure 2 The embodiment of the present application is a new special sealing element, the cross-sectional shape of the sealing element is mushroom-shaped which is connected by an arc-shaped part 1 and a trapezoidal part 2 connected to the bottom end of the arc-shaped part 1. In use, the trapezoidal part 2 of the sealing element is clamped in the sealing groove 100 which is matched with the outer shape of the sealing element. The height F between the connection of the arc-shaped part 1 and the trapezoidal part 2 and the vertex of the arc-shaped part 1 and the height G between the outer side edge of the arc-shaped part 1 and the vertex of the arc-shaped part 1 have a height difference, so that the two sides 11 of the connection of the arc-shaped part 1 and the trapezoidal part 2 respectively present an inclined surface shape, the inclination angle of the inclined surface shape is 2°-10°, which is beneficial to the close fit of the sealing element and the sealing groove. The middle part of the connection of the arc-shaped part 1 and the trapezoidal part 2 is provided with an oval hole 3, the ratio of the short axis H and the long axis B of the oval hole 3 is 1:2, which is beneficial to improve the elastic compression performance of the sealing element when compressed; the bottom end of the trapezoidal part 2 is provided with a rectangular opening 4, the ratio of the width C and the height J of the rectangular opening 4 is 3:2, which is beneficial to the elastic compression performance of the sealing element when compressed, the width of the lower base of the trapezoidal part 2 is greater than the width of the upper base, which is beneficial to prevent the sealing element from falling out of the sealing groove; the angles K of the two bottom corners of the lower base of the trapezoidal part 2 are respectively 70°-80°, which is beneficial to fix the sealing element in the sealing groove and prevent the sealing element from falling out of the sealing groove. The ratio of the overall width A and the height E of the cross section of the special sealing element is 2:1, the larger cross-sectional width size and height size are beneficial to ensure the sealing performance of the product.

[0022] The formula of the new special sealing element includes silica rubber compound and double-dioxide-four vulcanizing agent, without adding anti-scorching agent, vulcanization accelerator and activator. The minimum viscosity of the silica rubber compound is 2.2-6, the scorch time is 0.8-1.8 minutes, the tensile strength is greater than 1100 PS.I, the elongation at break is greater than 400%, the compression permanent deformation is less than 55%, the plasticity is 330-440, the shore A hardness is 50-70, and the specific gravity is 1-1.3.

[0023] In the formula of the new special sealing element, the base material is selected from silica rubber compound and double-dioxide-four vulcanizing agent. The use of double-dioxide-four vulcanizing agent is more advanced than sulfur vulcanization, without adding anti-scorching agent, vulcanization accelerator and activator, which is more beneficial to the vulcanization and molding of the product.

[0024] The preparation method of the new special sealing element includes the following steps:

[0025] S1, mixing step: the silica gel compound is mixed with the bis-dioxide vulcanizing agent in a mixing machine, the temperature of the compound is controlled at 26±2℃ during mixing, and the mixing is performed for 10 minutes, and the mixing uniformity is visually inspected;

[0026] S2, extrusion step: the mixed compound is placed in an extruder to obtain a rubber strip, the extrusion temperature is controlled at 26±2℃, and the extruder outlet is provided with a mold with the same tolerance as the product cross-sectional size for extrusion;

[0027] S3, parking step: the extruded rubber strip is parked, the parking temperature is controlled at 26±2℃, and the parking time is controlled within 30 minutes;

[0028] S4, vulcanization step: the parked rubber strip is placed on a horizontal conveyor belt, and is first subjected to hot air vulcanization in a high-temperature box, the vulcanization temperature of the high-temperature box is controlled at 170±5℃, and the vulcanization lasts for 20 minutes; the rubber strip directly enters a two-stage high-temperature box for hot air vulcanization along the horizontal conveyor belt, the vulcanization temperature of the two-stage high-temperature box is controlled at 200±5℃, and the vulcanization lasts for 4 hours; the vulcanized rubber strip is wound, and the length of each roll is not more than 100m;

[0029] S5, joint step: the rubber strip with the required length is cut, then the two ends of the rubber strip are butted, a gypsum rod is arranged in the joint for fixation, the joint is placed in a mold pressing device, glue is injected and partially vulcanized to form a joint, and then the gypsum rod is broken to ensure the integrity of the joint, thereby obtaining a molded new special sealing element.

[0030] The preparation method of the new special sealing element is as follows: the basic glue is mixed according to the listed formula, the manufacturing process scheme of mixing-extruding-parking-vulcanizing-joint-finished product is used for manufacturing, and the design and production are performed according to the structure size shown in the figure. The mixing temperature is controlled at 26±2℃, and the mixing is performed for 10 minutes. The extrusion temperature is controlled at 26±2℃, and the extrusion is performed for 5 minutes. The temperature of the rubber strip during parking is controlled at 26±2℃, and the parking time is controlled within 30 minutes. The rubber strip is placed in hot air, and two-stage vulcanization is adopted, the first-stage vulcanization temperature is controlled at 170±5℃, and the vulcanization lasts for 20 minutes. The second-stage vulcanization temperature is controlled at 200±5℃, and the vulcanization lasts for 4 hours. The joint of the special sealing element is formed by mold pressing, a gypsum rod is arranged in the joint for fixation during the forming process, the gypsum rod is broken after the joint is formed to ensure the integrity of the joint.

[0031] The preparation method of the new special sealing element uses the extrusion forming process, which saves cost compared with mold pressing forming. The extrusion forming can extrude a rubber strip with a length of more than 50m at a time. In use, the rubber strip is cut and spliced according to the product demand of the sealing element, and then vulcanized to form a product. The traditional mold pressing forming needs to be customized according to the product size, different size products need different molds, and the price is expensive.

[0032] The preparation method of the novel special sealing member of the application adopts a two-stage vulcanization process, which is more conducive to further cross-linking of the sealing glue than one-stage vulcanization, and increases the mechanical properties and compression permanent deformation properties of the product. And using hot air indirect vulcanization, compared with steam vulcanization, it is conducive to the appearance forming, is conducive to the product structure forming size and tolerance, and is conducive to the product surface quality. Using horizontal vulcanization, compared with vertical vulcanization, it is conducive to the appearance forming, is conducive to the product structure forming size and tolerance, and is conducive to the product surface quality.

[0033] According to the sealing member product demand, the rubber strip is cut and spliced and vulcanized to form, and a mold pressing forming splice is used at the joint, which is more complete than a glue joint cross-linking, enhances the mechanical properties of the joint, and makes the joint structure forming size complete.

[0034] The special sealing member of the application is suitable for high temperature environment, the maximum environmental humidity can be up to 100%, the gas medium environment can contain salt air, peroxide sodium aerosol, hot sodium, water vapor, etc., can withstand negative pressure or positive pressure, can resist mechanical aging, and can resist radiation.

[0035] In summary, the novel special sealing member of the application, its formula and preparation method have good elastic compression performance, can be closely attached to the sealing groove after being fixed in the sealing groove, can prevent the sealing member from falling off, have excellent sealing performance, and the novel special sealing member of the application is suitable for high temperature environment, the maximum environmental humidity can be up to 100%, the gas medium environment can contain salt air, peroxide sodium aerosol, hot sodium, water vapor, etc., can withstand negative pressure or positive pressure, can resist mechanical aging, and can resist radiation.

[0036] Those skilled in the art of the technical field should realize that the above embodiments are only used to illustrate the application, and are not used as a limitation on the application, and as long as the changes and modifications of the above described embodiments are within the scope of the spirit of the application, they will fall within the scope of the claims of the application.

Claims

1. A specialty seal, characterized in that, The cross-sectional shape of the sealing element is connected in a mushroom shape by an arc-shaped part and a trapezoidal part connected with the bottom end of the arc-shaped part, and the connection of the arc-shaped part and the trapezoidal part is in a slope shape on both sides, and the inclination angle of the slope shape is 2°-10°; The connection of the arc-shaped part and the trapezoidal part is provided with an oval hole in the middle, and the ratio of the short axis and the long axis of the oval hole is 1:2; The bottom end of the trapezoidal part is provided with a rectangular opening, and the ratio of the width and height of the rectangular opening is 3:2; The angle of the two bottom angles of the lower base of the trapezoidal part is 70°-80°, The formula of the special sealing element includes silicone rubber and double-dioxide vulcanizing agent, without adding anti-scorching agent, vulcanizing accelerator and activator; The scorch time of the silicone rubber is 0.8-1.8 minutes, the tensile strength is greater than 1100 PSI, the elongation at break is greater than 400%, the compression permanent deformation is less than 55%, and the Shore A hardness is 50-70.

2. A method of making the special seal of claim 1, wherein, The preparation method comprises the following steps: S1, mixing step: put the silicone rubber and double-dioxide vulcanizing agent into the mixing machine for mixing, control the temperature of the rubber material at 26±2℃ during mixing, mix for 10 minutes, and visually check the uniformity of mixing; S2, extrusion step: put the mixed rubber material into the extruder for extrusion to obtain a rubber strip, control the extrusion temperature at 26±2℃, and install a mold with the same tolerance as the product cross-sectional size at the outlet of the extruder for extrusion; S3, parking step: park the extruded rubber strip, control the parking temperature at 26±2℃, and control the parking time within 30 minutes; S4, vulcanization step: place the parked rubber strip on a horizontal conveyor belt, and first pass through a high-temperature box for hot air vulcanization, control the vulcanization temperature of the first high-temperature box at 170±5℃, and last for 20 minutes; the rubber strip directly enters a second high-temperature box for hot air vulcanization along the horizontal conveyor belt, the vulcanization temperature of the second high-temperature box is controlled at 200±5℃, and lasts for 4 hours; roll up the vulcanized rubber strip, and the length of each roll is not more than 100m; S5, joint step: cut the rubber strip to the required length, then butt joint the two ends of the rubber strip, fix the joint with a gypsum rod, put the joint into a mold pressing equipment, inject glue and locally vulcanize to form, break the gypsum rod after the joint is formed to ensure the integrity of the joint, and obtain the formed special sealing element.

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