Self-demoulding bisphenol fluororubber and full-automatic mould pressing production method thereof

Abstract

The application discloses a self-demoulding bisphenol fluororubber, raw materials of which include: 100 parts of fluororubber, 0.6-1 parts of bisphenol vulcanizing agent, 0.2-0.4 parts of vulcanization accelerator, 20-30 parts of modified white carbon black A, 3-7 parts of modified white carbon black B, 2-4 parts of zinc oxide, 5-7 parts of magnesium oxide and 1-3 parts of internal release agent; wherein, in the preparation process of the modified white carbon black, the mercapto-grafted white carbon black, octavinyl octasilsesquioxane, a photoinitiator and a solvent are uniformly mixed in an inert gas atmosphere, and then the mixture is subjected to a reaction under light to obtain the modified white carbon black. The application further discloses a full-automatic mould pressing production method of the self-demoulding bisphenol fluororubber. The application has good compression set resistance, and can avoid rubber deformation and tearing during self-demoulding, improve the qualified rate, reduce the labor cost, and shorten the single-mould secondary demoulding time from 30-60s to less than 3s.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, and in particular to a self-release bisphenol fluororubber and its fully automated molding production method. Background Technology

[0002] Bisphenol fluororubber is commonly used in the manufacture of seals. Its preparation method generally involves: after the compounded rubber is recycled and sheeted on an open mill, it is cut into pre-formed strips matching the mold size using a rubber cutter. These strips are then subjected to a first-stage vulcanization molding process on a flatbed molding press. After demolding, a second-stage vulcanization process yields the finished product. However, in actual production, manual demolding is required. Throughout the process, workers need to monitor a machine and perform related auxiliary tasks. The environment is hot and noisy, and workers inevitably inhale vulcanization fumes. Furthermore, the vulcanization machine typically reaches temperatures of approximately 170°C, posing a risk of burns to manual operators. Automated rubber production has always been a popular area in the industry, but after fluororubber molding, problems such as rubber adhesion to the mold, difficulty in demolding, and easy tearing and damage of the molded rubber during demolding lead to a low yield rate, making automated production difficult. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a self-release bisphenol fluororubber and its fully automated molding production method. The present invention has good resistance to compression set and can avoid deformation and tearing of the rubber material while self-demolding, thereby improving the pass rate, reducing labor costs, and shortening the demolding time of a single mold from 30-60s to less than 3s.

[0004] This invention proposes a self-release bisphenol fluororubber, the raw materials of which include, by weight: 100 parts fluororubber, 0.6-1 parts bisphenol vulcanizing agent, 0.2-0.4 parts vulcanization accelerator, 20-30 parts modified silica A, 3-7 parts modified silica B, 2-4 parts zinc oxide, 5-7 parts magnesium oxide, and 1-3 parts internal release agent; In the preparation of modified silica A, in an inert gas atmosphere, grafted mercapto silica, octavinyloctasilylsesquioxane, photoinitiator and solvent are mixed and reacted under light to obtain modified silica A.

[0005] The aforementioned silane coupling agents containing thiol groups can be γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, etc.

[0006] The above-mentioned photoinitiator can be 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone, etc., and the above-mentioned solvent can be tetrahydrofuran, etc.

[0007] The aforementioned silica can be TOKUSIL 532EP, etc., and the aforementioned fluororubber can be Chenguang Chemours CA-401C, etc.

[0008] The raw materials for the aforementioned self-release bisphenol fluororubber may also include pigments, etc.

[0009] Preferably, in the preparation of modified silica A, the sulfhydryl-grafted silica is silicone modified by grafting with a silane coupling agent containing sulfhydryl groups.

[0010] Preferably, in the preparation of modified silica A, the weight ratio of octavinyloctasilylsilsesquioxane, photoinitiator, and grafted thiol silica is 1:0.008-0.012:10-15. In the preparation of modified silica A, the reaction is carried out under light for 25-35 minutes.

[0011] Preferably, the modified silica B is silica coated with carnauba wax and erucamide.

[0012] Preferably, in the preparation of modified silica B, silica is mixed with molten carnauba wax and erucamide, and then cooled to obtain modified silica B.

[0013] Preferably, in the preparation of modified silica B, the weight ratio of carnauba wax to erucamide is 4-5:1; In the preparation of modified silica B, the ratio of the total weight of carnauba wax and erucamide to the weight of silica is 1-5:100.

[0014] Preferably, the bisphenol vulcanizing agent is hexafluorobisphenol A benzyltriphenyl salt; the vulcanization accelerator is benzyltriphenylphosphine chloride.

[0015] The aforementioned internal release agent is WS280, which can be purchased from the market, such as from Struktol.

[0016] This invention also proposes a fully automated molding production method for the above-mentioned self-release bisphenol fluororubber, comprising the following steps: at 60-70℃, fluororubber is mixed uniformly with magnesium oxide, zinc oxide, modified silica A, modified silica B, and internal release agent in sequence; the temperature is lowered to 35-45℃; bisphenol vulcanizing agent and vulcanization accelerator are added and mixed uniformly; molding is performed with a first-stage vulcanization, followed by demolding and a second-stage vulcanization to obtain self-release bisphenol fluororubber.

[0017] Preferably, the gas is sprayed for purging and demolding, with a spray pressure of 0.4-0.6 MPa and a spray time of 2-5 seconds.

[0018] The gas being injected is compressed air.

[0019] Preferably, the temperature of the first stage of vulcanization is 165-170℃ and the time is 180-300s; the temperature of the second stage of vulcanization is 200-230℃ and the time is 10-12h.

[0020] This invention uses modified silica B in combination with an internal release agent, and selects an appropriate vulcanization temperature and time in conjunction with the production workshop to adjust the vulcanization rate of the rubber compound, optimize the heat tear resistance of fluororubber at high temperatures, solve the problem of fluororubber sticking to the mold during vulcanization, and realize fully automated production of fluororubber; while maintaining good product performance, balancing the elasticity and rigidity of the rubber compound, and maintaining good resistance to compression set.

[0021] This invention uses carnauba wax and erucamide, which have good lubricity, to coat silica, thus preventing silica agglomeration, improving its dispersibility in rubber, and significantly reducing the coefficient of friction of silica. This allows silica to act like ball bearings during rubber mixing and molding, improving rubber flowability and reducing demolding resistance. Furthermore, carnauba wax and erucamide also improve the flowability of fluororubber. The combination of these three ingredients enhances the self-demolding performance of fluororubber. During fluororubber vulcanization, carnauba wax forms a low surface energy insulating film at the rubber-mold interface, and erucamide migrates from the rubber matrix to the surface to form a lubricating film, reducing the interfacial friction coefficient. The synergistic effect of these three ingredients gives fluororubber excellent self-demolding properties. Additionally, silica B improves the compression set resistance of fluororubber. Moreover, this invention controls the amount of modified silica B used to prevent blooming. Furthermore, this invention grafts octavinyloctasilylsilsesquioxane with a nanocage-like structure onto the surface of silica to form a core-shell structure, which significantly improves the dispersibility of silica in fluororubber, prevents agglomeration, and the remaining carbon-carbon double bonds can increase the vulcanization crosslinking density, so that the modified silica is firmly anchored in the three-dimensional network of fluororubber. When the rubber is compressed, the anchor points of these core-shell structures can effectively restrict the irreversible slippage and collapse of the rubber molecular chains, allowing it to rebound more quickly and thoroughly after the pressure is released, thereby significantly improving the resistance to compression set and tear resistance, thus avoiding the problem of easy tearing of products when demolding with purging gas; and it can also improve the wear resistance of rubber materials.

[0022] This invention eliminates the need for dedicated demolding personnel, reduces costs, and avoids deformation and tearing of the rubber material caused by demolding, thereby improving the product qualification rate. The resulting product still maintains good tensile strength and resistance to compression set, meeting the conventional performance requirements of fluororubber seals. The demolding time per mold can be shortened from 30-60 seconds to less than 3 seconds, and can be automatically generated for 10-12 shifts continuously.

[0023] The self-release bisphenol vulcanized fluororubber of this invention can be used to prepare various sealing components such as O-rings, gaskets, and oil seals without modifying the mold structure. Attached Figure Description

[0024] Figure 1These are typical photographs of the demolded samples of Example 3 and Comparative Example 1, where a is Example 3 and b is Comparative Example 1. Detailed Implementation

[0025] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0026] Example 1 A self-release bisphenol fluororubber, the raw materials of which include, by weight: 100 parts of fluororubber CA-401C, 0.6 parts of hexafluorobisphenol A benzyltriphenyl salt, 0.2 parts of benzyltriphenylphosphine chloride (i.e., vulcanization accelerator BPP), 20 parts of modified silica A, 7 parts of modified silica B, 2 parts of zinc oxide, 5 parts of magnesium oxide, 1 part of internal release agent WS280, and 4 parts of green pigment; In the preparation of modified silica A, under a nitrogen atmosphere, 10g of γ-mercaptopropyltriethoxysilane modified silica, 1g of octavinyloctasilsesquioxane, and 0.008g of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone were added to 2L of tetrahydrofuran and mixed. The mixture was then irradiated with ultraviolet light for 35min, filtered, washed, and dried to obtain modified silica A. In the preparation of modified silica B, 0.08g of carnauba wax and 0.02g of erucamide were mixed and heated to 90℃ to melt them. Then, 10g of silica was added and stirred at 100r / min for 20min to mix evenly. Then, the mixture was cooled to room temperature in a water bath while stirring continuously during the cooling process to obtain modified silica B.

[0027] The fully automated molding production method of the above-mentioned self-release bisphenol fluororubber includes the following steps: Fluororubber is added to a mixer and mixed, then magnesium oxide and zinc oxide are added and mixed at 70°C, then modified silica A is added and mixed, then modified silica B and internal release agent WS280 are added and mixed evenly, then the temperature is lowered to 45°C, bisphenol vulcanizing agent FL-5 and benzyltriphenylphosphine chloride are added and mixed evenly, then injected into a mold (the surface of the mold is coated with an external release agent), molded and vulcanized at 165°C for 300s, then demolded by spraying compressed air (spraying pressure is 0.4MPa, spraying time is 5s), and then vulcanized at 200°C for 12h to obtain self-release bisphenol fluororubber.

[0028] Example 2 A self-release bisphenol fluororubber, the raw materials of which include, by weight: 100 parts of fluororubber CA-401C, 1 part of bisphenol vulcanizing agent FL-5, 0.4 parts of benzyltriphenylphosphine chloride (i.e., vulcanization accelerator BPP), 30 parts of modified silica A, 3 parts of modified silica B, 4 parts of zinc oxide, 7 parts of magnesium oxide, 3 parts of internal release agent WS280, and 4 parts of green pigment; In the preparation of modified silica A, under a nitrogen atmosphere, 15g of γ-mercaptopropyltriethoxysilane modified silica, 1g of octavinyloctasilsesquioxane, and 0.012g of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone were added to 5L of tetrahydrofuran and mixed. The mixture was then irradiated with ultraviolet light for 25min, filtered, washed, and dried to obtain modified silica A. In the preparation of modified silica B, 0.41g of carnauba wax and 0.09g of erucamide were mixed and heated to 90℃ to melt them. Then, 10g of silica was added and stirred at 100r / min for 20min to mix evenly. The mixture was then cooled to room temperature in a water bath with continuous stirring during the cooling process to obtain modified silica B.

[0029] The fully automated molding production method of the above-mentioned self-release bisphenol fluororubber includes the following steps: fluororubber is added to a mixer and mixed, then magnesium oxide and zinc oxide are added and mixed at 60°C, then modified silica A is added and mixed, then modified silica B and internal release agent WS280 are added and mixed evenly, then the temperature is lowered to 35°C, bisphenol vulcanizing agent FL-5 and benzyltriphenylphosphine chloride are added and mixed evenly, then injected into a mold (the surface of the mold is coated with an external release agent), molded at 170°C for a first stage of vulcanization for 180s, compressed air is sprayed for demolding (spraying pressure is 0.6MPa, spraying time is 2s), and then vulcanized at 230°C for a second stage for 10h to obtain self-release bisphenol fluororubber.

[0030] Example 3 A self-release bisphenol fluororubber, the raw materials of which include, by weight: 100 parts of fluororubber CA-401C, 0.8 parts of bisphenol vulcanizing agent FL-5, 0.3 parts of benzyltriphenylphosphine chloride (i.e., vulcanization accelerator BPP), 25 parts of modified silica A, 5 parts of modified silica B, 3 parts of zinc oxide, 6 parts of magnesium oxide, 1.5 parts of internal release agent WS280, and 4 parts of green pigment; In the preparation of modified silica A, under a nitrogen atmosphere, 13g of γ-mercaptopropyltriethoxysilane modified silica, 1g of octavinyloctasilsesquioxane, and 0.01g of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone were added to 5L of tetrahydrofuran and mixed. The mixture was then irradiated with ultraviolet light for 30min, filtered, washed, and dried to obtain modified silica A. In the preparation of modified silica B, 0.2g of carnauba wax and 0.05g of erucamide were mixed and heated to 90℃ to melt them. Then, 10g of hollow glass microspheres were added and stirred at 100r / min for 20min to mix them evenly. The mixture was then cooled to room temperature in a water bath with continuous stirring during the cooling process to obtain modified silica B.

[0031] The fully automated molding production method of the above-mentioned self-release bisphenol fluororubber includes the following steps: fluororubber is added to a mixer and mixed, then magnesium oxide and zinc oxide are added and mixed at 65°C, then modified silica A is added and mixed, then modified silica B and internal release agent WS280 are added and mixed evenly, then the temperature is lowered to 40°C, bisphenol vulcanizing agent FL-5 and benzyltriphenylphosphine chloride are added and mixed evenly, then the mixture is injected into a mold (the surface of the mold is coated with an external release agent), and the first stage of vulcanization is performed at 170°C for 300s, then compressed air is sprayed for demolding (spraying pressure is 0.5MPa, spraying time is 4s), and then the second stage of vulcanization is performed at 220°C for 12h to obtain self-release bisphenol fluororubber.

[0032] Comparative Example 1 A self-release bisphenol fluororubber, wherein “modified silica A” is replaced with “a mixture of silica and octavinyl octasilsesquioxane in a weight ratio of 13:1”, otherwise the same as in Example 3.

[0033] Comparative Example 2 A self-release bisphenol fluororubber, wherein “modified silica B” is replaced with “a mixture of silica, carnauba wax and erucamide in a weight ratio of 10:0.2:0.05”, and the rest is the same as in Example 3.

[0034] Comparative Example 3 A self-release bisphenol fluororubber, wherein “25 parts of modified silica A and 5 parts of modified silica B” are replaced with “30 parts of silica”, and the rest is the same as in Example 3.

[0035] Following the methods of Examples 1-3 and Comparative Examples 1-3, more than 40 molds were continuously produced without adding additional external release agent. If each mold sample could be completely blown off the mold by compressed air after 40 continuous productions, it was determined that automatic demolding was possible; otherwise, it was determined that automatic demolding was not possible. Performance tests were conducted on the samples after two-stage vulcanization of Examples 1-3 and Comparative Examples 1-3, and the results are shown in Table 1 and... Figure 1 As shown.

[0036] Figure 1 These are typical photographs of the demolded samples of Example 3 and Comparative Example 1, where a is Example 3 and b is Comparative Example 1.

[0037] Table 1 Test Results

[0038] From Table 1 and Figure 1 It can be seen that the fluororubber of the present invention has a compression set of ≤25% at 200℃×70h, which shows good resistance to compression set; and it can be continuously and automatically demolded without damage or tearing of the sample.

[0039] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A self-release bisphenol fluororubber, characterized in that, The raw materials, by weight, include: 100 parts fluororubber, 0.6-1 parts bisphenol vulcanizing agent, 0.2-0.4 parts vulcanization accelerator, 20-30 parts modified silica A, 3-7 parts modified silica B, 2-4 parts zinc oxide, 5-7 parts magnesium oxide, and 1-3 parts internal release agent; In the preparation of modified silica A, in an inert gas atmosphere, grafted mercapto silica, octavinyloctasilylsesquioxane, photoinitiator and solvent are mixed and reacted under light to obtain modified silica A.

2. The self-release bisphenol fluororubber according to claim 1, characterized in that, In the preparation of modified silica A, the sulfhydryl-grafted silica is silicone modified by grafting with a silane coupling agent containing sulfhydryl groups.

3. The self-release bisphenol fluororubber according to claim 1 or 2, characterized in that, In the preparation of modified silica A, the weight ratio of octavinyloctasilylsilsesquioxane, photoinitiator, and grafted thiol silica is 1:0.008-0.012:10-15. In the preparation of modified silica A, the reaction is carried out under light for 25-35 minutes.

4. The self-release bisphenol fluororubber according to claim 1 or 2, characterized in that, Modified silica B is silica coated with carnauba wax and erucamide.

5. The self-release bisphenol fluororubber according to claim 1 or 2, characterized in that, In the preparation of modified silica B, silica is mixed with molten carnauba wax and erucamide, and then cooled to obtain modified silica B.

6. The self-release bisphenol fluororubber according to claim 5, characterized in that, In the preparation of modified silica B, the weight ratio of carnauba wax to erucamide is 4-5:

1. In the preparation of modified silica B, the ratio of the total weight of carnauba wax and erucamide to the weight of silica is 1-5:

100.

7. The self-release bisphenol fluororubber according to claim 1 or 2, characterized in that, The bisphenol vulcanizing agent is hexafluorobisphenol A benzyltriphenyl salt; the vulcanization accelerator is benzyltriphenylphosphine chloride.

8. A fully automated molding production method for self-release bisphenol fluororubber as described in any one of claims 1-7, characterized in that, The process includes the following steps: at 60-70℃, fluororubber is mixed with magnesium oxide, zinc oxide, modified silica A, modified silica B, and internal release agent in sequence until homogeneous. The mixture is then cooled to 35-45℃, and bisphenol vulcanizing agent and vulcanization accelerator are added and mixed until homogeneous. The mixture is then molded and vulcanized in one stage, demolded, and vulcanized in a second stage to obtain self-release bisphenol fluororubber.

9. The fully automated molding production method for self-release bisphenol fluororubber according to claim 8, characterized in that, Gas is sprayed to purge and demold the mold. The spraying pressure is 0.4-0.6 MPa and the spraying time is 2-5 seconds.

10. The fully automated molding production method for self-release bisphenol fluororubber according to claim 8, characterized in that, The temperature for the first stage of vulcanization is 165-170℃, and the time is 180-300s; the temperature for the second stage of vulcanization is 200-230℃, and the time is 10-12h.

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