Perfluoroether rubber sealing element

Abstract

The invention discloses a perfluoroether rubber sealing element, and belongs to the technical field of rubber materials, the perfluoroether rubber sealing element comprises 100 parts of perfluoroether rubber, 1-5 parts of modified graphene oxide, 1-5 parts of a cross-linking agent, 6-9 parts of a filler, 1-5 parts of an acid acceptor, and 1-2 parts of an accelerator; the modified graphene is graphene oxide modified by silane coupling agent grafted ionic liquid; the silane coupling agent grafted ionic liquid is obtained by reacting amino-terminated imidazole unsaturated ionic liquid with an epoxy silane coupling agent. The silane coupling agent grafted ionic liquid modified graphene oxide is used as a raw material to be added into the preparation process of the perfluoroether rubber sealing element, so that the perfluoroether rubber sealing element has good medium resistance under the condition that the stable hardness and tensile strength of the perfluoroether rubber sealing element are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber materials, and in particular relates to a perfluoroether rubber seal. Background Art

[0002] At present, most of the equipment involved in the optoelectronic industry operates in a harsh environment, such as operating under high temperature conditions and nitrogen environment. Nitrogen will react to ammonia under high temperature conditions, and ammonia will be alkaline after decomposition. In this environment, ordinary O-type rubber sealing rings are difficult to meet the sealing effect of the equipment. Long-term exposure to high temperature and alkaline environment will corrode the main chain of rubber molecules, causing the rubber performance to deteriorate and leading to sealing failure.

[0003] Material properties are the decisive factor in the performance of sealing products. During operation, they are in a harsh environment of highly corrosive media, humidity, heat and high wear. Due to the harsh environment, the materials used must be able to withstand long-term chemical, high temperature, high humidity and mechanical loads, and their performance has special requirements. Because once the seal fails, it will not only greatly increase the subsequent maintenance costs, but may also lead to fatal disasters. Therefore, it is very necessary to improve the corrosion resistance of seals. Summary of the invention

[0004] The object of the present invention is to provide a perfluoroether rubber seal to solve the problem of poor corrosion resistance of the seal.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A perfluoroether rubber seal comprises the following raw materials in parts by weight: 100 parts of perfluoroether rubber, 1-5 parts of modified graphene oxide, 1-5 parts of crosslinking agent, 6-9 parts of filler, 1-5 parts of acid absorber, and 1-2 parts of promoter; the modified graphene is graphene oxide modified by silane coupling agent grafted ionic liquid; the silane coupling agent grafted ionic liquid is obtained by epoxy ring-opening reaction of terminal aminoimidazole unsaturated ionic liquid and epoxy silane coupling agent. All hydrogen atoms in the molecular chain of perfluoroether rubber are replaced by fluorine atoms, and it is a rubber that does not contain CH bonds at all. Therefore, perfluoroether rubber has better chemical stability than other fluororubbers and can be used in more harsh medium environments. Therefore, perfluoroether rubber is used as the base rubber in the present invention.

[0007] Furthermore, the modified graphene is prepared by the following steps:

[0008] The silane coupling agent grafted ionic liquid was added to an ethanol aqueous solution with a volume fraction of 80%, the system was adjusted to be acidic, and then a graphene oxide ethanol dispersion with a mass fraction of 1% was added, and the temperature was raised to 70°C for reaction for 2 hours. After the reaction, it was washed with ethanol and water in turn, and dried to obtain modified graphene. Functional modification of silane coupling agent grafted ionic liquid can bring more reactive sites.

[0009] Furthermore, the usage ratio of the silane coupling agent grafted ionic liquid, the ethanol aqueous solution and the graphene oxide ethanol dispersion is 3-6g:100g:100g.

[0010] Further, the silane coupling agent grafted ionic liquid is prepared by the following steps:

[0011] Add vinyl imidazole monomer and ethyl bromide hydrobromide into ethanol, mix, heat under reflux for 24 hours, and obtain amino-terminated imidazole unsaturated ionic liquid through recrystallization, drying and alcohol washing;

[0012] Add the terminal amino imidazole unsaturated ionic liquid into ethanol and stir to dissolve, add the epoxy silane coupling agent and stir to disperse, set the temperature to 40-45° C., stir to react for 24 hours, and obtain the silane coupling agent grafted ionic liquid.

[0013] Furthermore, the molar ratio of the vinyl imidazole monomer to bromoethylamine hydrobromide is 1.125:1; the molar ratio of bromoethylamine hydrobromide to the epoxy silane coupling agent is 1:1.

[0014] Furthermore, the vinyl imidazole monomer is one of vinyl imidazole and N-allylimidazole.

[0015] Further, the cross-linking agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane;

[0016] The filler is at least one of carbon black N990, carbon black N774 and carbon black N550;

[0017] The acid absorbent is zinc oxide;

[0018] The accelerator is triallyl isocyanurate.

[0019] Further, the perfluoroether rubber seal is prepared by the following steps:

[0020] The raw materials are weighed according to weight parts, the perfluoroether rubber is plasticized, and then the modified graphene oxide, cross-linking agent, filler, acid absorber and accelerator are put into an internal mixer and mixed for 5 to 8 minutes; the rubber is discharged to an open mixer for tableting and cooling to obtain a rubber mixture; the rubber mixture is put into a mold, and after one-stage vulcanization and two-stage vulcanization, it is taken out and naturally cooled.

[0021] Further, a first stage vulcanization is performed, and the vulcanization conditions are 160°C / 13MPa×(20-25)min.

[0022] Further, two-stage vulcanization is performed, and the vulcanization conditions are 220°C×24h.

[0023] Beneficial effects of the present invention:

[0024] The invention prepares a perfluoroether rubber seal. Graphene oxide modified by silane coupling agent grafted ionic liquid is added as modified graphene oxide in the preparation process of the perfluoroether rubber seal. The perfluoroether rubber seal has good medium resistance while ensuring stable hardness and tensile strength.

[0025] In the present invention, the modified graphene oxide prepared by the epoxy ring-opening reaction of the terminal amino imidazole unsaturated ionic liquid and the epoxy silane coupling agent immobilizes the ionic liquid on the graphene oxide, thereby improving the dispersibility of the graphene oxide and improving the mechanical properties (such as tensile strength) of the perfluoroether rubber sealing sample; the modified graphene oxide not only introduces the ionic liquid, but also introduces double bonds that can participate in cross-linking through the ionic liquid, and can also "anchor" the graphene to the rubber substrate through the ion-π effect and the π-π effect, thereby giving full play to the role of the graphene oxide in improving the mechanical properties and acting as a barrier medium in the rubber substrate. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions 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 creative work are within the scope of protection of the present invention.

[0027] In this embodiment, a perfluoroether rubber seal is proposed, which includes the following raw materials in parts by weight: 100 parts of perfluoroether rubber, 1-5 parts of modified graphene oxide, 1-5 parts of a cross-linking agent, 6-9 parts of a filler, 1-5 parts of an acid absorber, and 1-2 parts of a promoter; the modified graphene is graphene oxide modified by a silane coupling agent grafted with an ionic liquid; the silane coupling agent grafted with an ionic liquid is obtained by reacting an aminoimidazole-terminated unsaturated ionic liquid with an epoxy silane coupling agent.

[0028] In some specific embodiments, the modified graphene is prepared by the following steps:

[0029] The silane coupling agent grafted ionic liquid was added to an ethanol aqueous solution with a volume fraction of 80%, the system was adjusted to be acidic, and then a graphene oxide ethanol dispersion with a mass fraction of 1% was added, the temperature was raised to 70°C and reacted for 2 hours. After the reaction, it was washed with ethanol and water in turn and dried to obtain modified graphene.

[0030] The amount ratio of the silane coupling agent grafted ionic liquid, the ethanol aqueous solution and the graphene oxide ethanol dispersion is 3-6g:100g:100g. In the embodiment, the amount of the silane coupling agent grafted ionic liquid can be 3g, 4g, 5g, 6g and other typical but non-limiting amounts or a range value between any two amounts. Within this amount range, the modified graphene can achieve higher or stable performance in the rubber matrix.

[0031] In some specific embodiments, the silane coupling agent grafted ionic liquid is prepared by the following steps:

[0032] Add vinyl imidazole monomer and ethyl bromide hydrobromide into ethanol, mix, heat under reflux for 24 hours, and obtain amino-terminated imidazole unsaturated ionic liquid through recrystallization, drying and alcohol washing;

[0033] Add an amino imidazole-terminated unsaturated ionic liquid to ethanol and stir to dissolve, add an epoxy silane coupling agent and stir to disperse, set the temperature to 40-45°C, stir and react for 24 hours to obtain a silane coupling agent grafted ionic liquid. In the embodiment, the temperature can be set to 40°C, 41°C, 42°C, 43°C, 44°C and 45°C, etc., which are typical but non-limiting amounts or range values ​​between any two amounts. Within this amount range, the amino group in the amino imidazole-terminated unsaturated ionic liquid and the epoxy group of the epoxy silane coupling agent undergo an epoxy ring-opening reaction to obtain a silane coupling agent grafted ionic liquid.

[0034] In some specific embodiments, the molar ratio of the vinyl imidazole monomer to bromoethylamine hydrobromide is 1.125:1; the molar ratio of bromoethylamine hydrobromide to the epoxy silane coupling agent is 1:1.

[0035] In some specific embodiments, the vinyl imidazole monomer is one of vinyl imidazole and N-allyl imidazole. In the selection of the vinyl imidazole monomer in the embodiment, it is necessary to ensure that at least one double bond can be introduced, thereby introducing multiple double bonds that can participate in cross-linking into the graphene oxide, thereby enhancing the mechanical properties of the perfluoroether rubber seal sample.

[0036] In some specific embodiments, the cross-linking agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane;

[0037] The filler is at least one of carbon black N990, carbon black N774 and carbon black N550;

[0038] The acid absorbent is zinc oxide;

[0039] In some specific embodiments, the accelerator is triallyl isocyanurate.

[0040] Weigh the raw materials according to the weight, plasticize the perfluoroether rubber, and then put the modified graphene oxide, crosslinking agent, filler, acid absorber and accelerator into the internal mixer for mixing for 5 to 8 minutes; discharge the rubber to the open mixer for tableting and cooling to obtain the mixed rubber; put the mixed rubber into the mold, and cool it naturally after the first and second stage vulcanization. The first stage vulcanization condition is 160℃ / 13MPa×(20~25)min. The second stage vulcanization condition is 220℃×24h.

[0041] The following is further described in conjunction with specific embodiments.

[0042] Preparation Example 1

[0043] Preparation of modified graphene:

[0044] Add vinyl imidazole monomer (vinyl imidazole, N-allylimidazole) and bromoethylamine hydrobromide to ethanol, mix, heat and reflux for 24 hours, after the reaction, remove ethanol by rotary evaporation, add a small amount of ethanol for recrystallization, add KOH to neutralize to pH ≥ 8, and vacuum dry for 8 hours. Add appropriate amount of ethanol, stir, filter, remove KBr, and rotary evaporate to obtain an amino-terminated imidazole unsaturated ionic liquid;

[0045] The terminal amino imidazole unsaturated ionic liquid was added to ethanol and stirred to dissolve, and the epoxy silane coupling agent (KH-560) was added and stirred to disperse, and the temperature was set to 40°C, and the reaction was stirred for 24 hours. After the reaction, the ethanol solvent in the reaction liquid was removed by a rotary evaporator to obtain the silane coupling agent grafted ionic liquid. The molar ratio of the vinyl imidazole monomer and bromoethylamine hydrobromide was 1.125:1; the molar ratio of bromoethylamine hydrobromide and epoxy silane coupling agent was 1:1.

[0046] The silane coupling agent grafted ionic liquid was added to an ethanol aqueous solution with a volume fraction of 80%, the pH value was adjusted to 4.5 with acetic acid, and then a graphene oxide ethanol dispersion with a mass fraction of 1% was added, and the temperature was raised to 70°C for reaction for 2 hours. After the reaction, it was washed with ethanol and water in turn and dried to obtain modified graphene. The amount ratio of the silane coupling agent grafted ionic liquid, the ethanol aqueous solution and the graphene oxide ethanol dispersion was 3g:100g:100g.

[0047] Preparation Example 2

[0048] Compared with Preparation Example 1, the vinyl imidazole monomer in this Preparation Example is replaced with N-allylimidazole, and the remaining raw materials and preparation process remain the same as those in Preparation Example 1.

[0049] Preparation Example 3

[0050] Compared with Preparation Example 1, the usage ratio of silane coupling agent grafted ionic liquid, ethanol aqueous solution and graphene oxide ethanol dispersion is 5g:100g:100g, and the other raw materials and preparation process remain the same as those in Preparation Example 1.

[0051] Preparation Example 4

[0052] Compared with Preparation Example 1, the usage ratio of silane coupling agent grafted ionic liquid, ethanol aqueous solution and graphene oxide ethanol dispersion is 6g:100g:100g, and the other raw materials and preparation process remain the same as those in Preparation Example 1.

[0053] Preparation Example 5

[0054] Compared with Preparation Example 1, the vinyl imidazole monomer in this Preparation Example is replaced with N-ethyl imidazole, and the remaining raw materials and preparation process remain the same as those in Preparation Example 1.

[0055] Preparation Example 6

[0056] Compared with Preparation Example 1, the silane coupling agent grafted ionic liquid in this Preparation Example is replaced with a silane coupling agent (KH570), and the remaining raw materials and preparation process remain the same as those in Preparation Example 1.

[0057] Specifically: add silane coupling agent (KH570) to ethanol aqueous solution with a volume fraction of 80%, adjust the pH value to 4.5 with acetic acid, then add 1% graphene oxide ethanol dispersion, heat to 70°C and react for 2 hours, wash with ethanol and water in turn after the reaction, and dry to obtain modified graphene. The amount ratio of silane coupling agent (KH570), ethanol aqueous solution and graphene oxide ethanol dispersion is 3g:100g:100g.

[0058] Example 1

[0059] This embodiment provides a perfluoroether rubber seal, comprising the following raw materials in parts by weight: 100 parts of perfluoroether rubber (perfluoroether PFE40Z), 5 parts of modified graphene oxide prepared in Preparation Example 1, 1.5 parts of a cross-linking agent (2,5-dimethyl-2,5-di(tert-butylperoxy)hexane), 9 parts of a filler (carbon black N990), 1 part of an acid absorber (zinc oxide), and 2 parts of a promoter (triallyl isocyanurate);

[0060] Ammonia-resistant and high-temperature-resistant perfluoroether rubber seal is prepared by the following steps:

[0061] The raw materials were weighed according to weight, and the perfluoroether rubber was plasticized, and then the modified graphene oxide, the crosslinking agent (2,5-dimethyl-2,5-di(tert-butylperoxy)hexane), the filler (carbon black N990), the acid absorber (zinc oxide), and the accelerator (triallyl isocyanurate) were put into an internal mixer and mixed for 5 to 8 minutes; the rubber was discharged to an open mixer for tableting and cooling to obtain a mixed rubber;

[0062] Put the mixed rubber into the mold of the O-ring and perform the first stage vulcanization on a flat vulcanizer at 160℃ / 13MPa×20min. After the vulcanization is completed, take out the mold, let it cool naturally and demould. Put the first stage vulcanized rubber into a vacuum oven for the second stage vulcanization at 220℃×24h, and cool naturally after taking it out.

[0063] Embodiment 2 to Embodiment 5 are the same as Embodiment 1, except that the raw material ratio in Embodiment 1 is adjusted, wherein the formulas of Embodiment 1 to Embodiment 5 are shown in Table 1:

[0064] Table 1

[0065] project Perfluoroether rubber Modified graphene oxide filler Crosslinking agent Acid absorbent Accelerator Example 1 100 copies 5 servings 9 servings 1.5 servings 1 serving 2 servings Example 2 100 copies 3 servings 9 servings 1.5 servings 1 serving 2 servings Example 3 100 copies 1 serving 9 servings 1.5 servings 1 serving 2 servings Example 4 100 copies 5 servings 6 servings 1.5 servings 1 serving 2 servings Example 5 100 copies 3 servings 6 servings 1.5 servings 1 serving 2 servings Example 6 100 copies 1 serving 6 servings 1.5 servings 1 serving 2 servings

[0066] Example 7

[0067] Compared with Example 1, the modified graphene oxide prepared in Preparation Example 1 is replaced by the modified graphene oxide prepared in Preparation Example 2, and the other raw materials and preparation process remain the same as those in Example 1.

[0068] Example 8

[0069] Compared with Example 1, the modified graphene oxide prepared in Preparation Example 1 is replaced by the modified graphene oxide prepared in Preparation Example 3, and the other raw materials and preparation process remain the same as those in Example 1.

[0070] Example 9

[0071] Compared with Example 1, the modified graphene oxide prepared in Preparation Example 1 is replaced by the modified graphene oxide prepared in Preparation Example 4, and the other raw materials and preparation process remain the same as those in Example 1.

[0072] Comparative Example 1

[0073] Compared with Example 1, the modified graphene oxide prepared in Preparation Example 1 is replaced by the modified graphene oxide prepared in Preparation Example 5, and the other raw materials and preparation process are the same as those in Example 1. (No double bond)

[0074] Comparative Example 2

[0075] Compared with Example 1, the modified graphene oxide prepared in Preparation Example 1 is replaced by the modified graphene oxide prepared in Preparation Example 6, and the other raw materials and preparation process are the same as those in Example 1. (With double bonds and without ionic liquid)

[0076] Comparative Example 3

[0077] Compared with Example 1, the modified graphene oxide prepared in Preparation Example 1 is replaced by untreated graphene oxide in this example, and the other raw materials and preparation process remain the same as those in Example 1.

[0078] Comparative Example 4

[0079] Compared with Example 1, in this example, the modified graphene oxide prepared in Preparation Example 1 is replaced with untreated graphene oxide, and the amount of untreated graphene oxide is adjusted to 1 part, and the other raw materials and preparation process remain the same as in Example 1.

[0080] Performance tests were performed on the test samples prepared in Examples 1 to 9 and Comparative Examples 1 to 3, including Shore A hardness, tensile strength and medium resistance.

[0081] Wherein, (1) Shore A hardness: The test is conducted in accordance with GB / T531.1-2008 “Test method for indentation hardness of vulcanized rubber or thermoplastic rubber Part 1: Shore A durometer method (Shore hardness)”.

[0082] (2) Tensile strength: The test is carried out in accordance with GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0083] (3) Medium resistance: Tested in accordance with GB / T1690-2010 "Test method for liquid resistance of vulcanized rubber or thermoplastic rubber".

[0084] The test results are shown in Table 2:

[0085] Table 2

[0086]

[0087] From the test results, it can be seen that the samples prepared by the present invention have good mechanical properties. According to Examples 1 to 6, within a certain range, as the amount of modified graphene oxide increases, the tensile properties show a trend of first increasing and then decreasing, and the floating range is small, reflecting high stability, and the modified graphene oxide has good compatibility with the substrate. In contrast, the tensile properties of the samples corresponding to Comparative Examples 1 to 4 are relatively poor, wherein the modified graphene oxide used in Comparative Example 1 is only modified by conventional ionic liquids, and the dispersibility is relatively good, but the chemical crosslinking points with the substrate in the subsequent vulcanization process are relatively few, which is not conducive to the improvement of the overall property. In Comparative Example 2, conventional unsaturated silane coupling agents are selected. Compared with ionic liquids, conventional silane coupling agents have poor high temperature resistance, which is not conducive to the improvement of dispersion performance; the samples corresponding to Comparative Examples 3 and 4 are not modified. When the amount of graphene oxide is large, the agglomeration phenomenon is serious, and stress concentration is generated when the sample is pulled, resulting in a decrease in tensile strength.

[0088] To test the medium resistance of the sample, the sample was immersed in alkaline potassium hydroxide solution (50% by mass) and acidic hydrofluoric acid solution (49% by mass) at 23°C for 720 hours. The hardness change, tensile strength change and volume change of the sample were recorded. The results are shown in Table 3 below:

[0089] Table 3

[0090]

[0091] From the test results, it can be seen that the medium resistance prepared by the present invention is good.

[0092] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0093] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A perfluoroether rubber seal, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of perfluoroether rubber, 1 to 5 parts of modified graphene oxide, 1 to 5 parts of a cross-linking agent, 6 to 9 parts of a filler, 1 to 5 parts of an acid absorber, and 1 to 2 parts of a promoter; the modified graphene is graphene oxide modified by a silane coupling agent grafted with an ionic liquid; the silane coupling agent grafted with an ionic liquid is obtained by reacting an aminoimidazole-terminated unsaturated ionic liquid with an epoxy silane coupling agent.

2. A perfluoroether rubber seal according to claim 1, characterized in that: The modified graphene is prepared by the following steps: The silane coupling agent grafted ionic liquid was added to an ethanol aqueous solution with a volume fraction of 80%, the system was adjusted to be acidic, and then a graphene oxide ethanol dispersion with a mass fraction of 1% was added, the temperature was raised to 70°C and reacted for 2 hours. After the reaction, it was washed with ethanol and water in turn and dried to obtain modified graphene.

3. A perfluoroether rubber seal according to claim 2, characterized in that: The dosage ratio of the silane coupling agent grafted ionic liquid, the ethanol aqueous solution and the graphene oxide ethanol dispersion is 3-6g:100g:100g.

4. A perfluoroether rubber seal according to claim 1, characterized in that: The silane coupling agent grafted ionic liquid is prepared by the following steps: Add vinyl imidazole monomer and ethyl bromide hydrobromide into ethanol, mix, heat under reflux for 24 hours, and obtain amino-terminated imidazole unsaturated ionic liquid through recrystallization, drying and alcohol washing; Add the terminal amino imidazole unsaturated ionic liquid into ethanol and stir to dissolve, add the epoxy silane coupling agent and stir to disperse, set the temperature to 40-45° C., stir to react for 24 hours, and obtain the silane coupling agent grafted ionic liquid.

5. A perfluoroether rubber seal according to claim 4, characterized in that: The molar ratio of the vinyl imidazole monomer to bromoethylamine hydrobromide is 1.125:1; the molar ratio of bromoethylamine hydrobromide to the epoxy silane coupling agent is 1:

1.

6. A perfluoroether rubber seal according to claim 4, characterized in that: The vinyl imidazole monomer is one of vinyl imidazole and N-allylimidazole.

7. A perfluoroether rubber seal according to claim 1, characterized in that: The cross-linking agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; The filler is at least one of carbon black N990, carbon black N774 and carbon black N550; The acid absorbent is zinc oxide; The accelerator is triallyl isocyanurate.

8. A perfluoroether rubber seal according to claim 1, characterized in that: Prepared by the following steps: The raw materials are weighed according to weight parts, the perfluoroether rubber is plasticized, and then the modified graphene oxide, cross-linking agent, filler, acid absorber and accelerator are put into an internal mixer and mixed for 5 to 8 minutes; the rubber is discharged to an open mixer for tableting and cooling to obtain a rubber mixture; the rubber mixture is put into a mold, and after one-stage vulcanization and two-stage vulcanization, it is taken out and naturally cooled.

9. A perfluoroether rubber seal according to claim 8, characterized in that: One-stage vulcanization, the vulcanization conditions are 160℃ / 13MPa×(20~25)min.

10. A perfluoroether rubber seal according to claim 8, characterized in that: Two-stage vulcanization, the vulcanization conditions are 220℃×24h.

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