Low-pressure variable sealing ring applied to new energy air conditioner and preparation method thereof

Abstract

This application relates to the field of fluororubber sealing materials, and discloses a low-pressure variable sealing ring for use in new energy air conditioners and its preparation method. The low-pressure variable sealing ring for new energy air conditioners is prepared from the following raw materials in parts by weight: 50-60 parts pretreated fluororubber, 30-40 parts EPDM rubber, 25-35 parts filler, 5-10 parts plasticizer, 4-8 parts crosslinking agent, 3-6 parts vulcanizing agent, and 1-3 parts antioxidant. The pretreated fluororubber is prepared by compounding fluororubber, liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, and allyl glycidyl ether. The sealing ring prepared in this application, when used in new energy vehicle air conditioners, has low cost and low-temperature stability, and maintains good low compression set under long-term refrigerant conditions, exhibiting good sealing stability.

Description

Technical Field

[0001] This application relates to the field of fluororubber sealing materials, and more specifically, it relates to a low-pressure variable sealing ring for use in new energy air conditioners and its preparation method. Background Technology

[0002] The sealing ring of a new energy vehicle's air conditioning system is one of the key components ensuring its normal operation. During operation, the refrigerant and other fluids in the air conditioning system of a new energy vehicle generate a certain pressure during circulation. The sealing ring needs to be able to withstand this pressure without leakage. Therefore, the sealing ring needs to have sufficient low compression deformation capacity and mechanical properties to ensure that it can maintain a good sealing effect under high pressure, high temperature and refrigerant environment.

[0003] To improve the aforementioned properties of sealing rings, fluororubber is generally used as the main material, compounded with fillers and other additives to prepare the sealing rings. Fluororubber exhibits good aging resistance and maintains good low compression set under complex high-temperature and high-pressure environments.

[0004] However, fluororubber is generally more expensive and has lower temperature resistance in the low-temperature environment of refrigerants. The resulting sealing rings are expensive and prone to deformation and cracking in low-temperature environments, which reduces the sealing stability of the sealing rings in the refrigerant environment. Summary of the Invention

[0005] To address the issues of high cost and susceptibility to deformation and cracking in low-temperature environments, which reduces the sealing stability of sealing rings in refrigerant environments, this application provides a low-pressure variable sealing ring for use in new energy air conditioners and its preparation method.

[0006] In a first aspect, this application provides a low-pressure variable sealing ring for use in new energy air conditioners, employing the following technical solution:

[0007] A low-pressure variable sealing ring for use in new energy air conditioners is made from the following raw materials in parts by weight:

[0008] 50-60 parts of pretreated fluororubber

[0009] 30-40 parts EPDM rubber

[0010] 25-35 parts of filler

[0011] 5-10 parts plasticizer

[0012] 4-8 parts of crosslinking agent

[0013] 3-6 parts of vulcanizing agent

[0014] Anti-aging agent 1-3 parts;

[0015] The pretreated fluororubber is prepared by compounding fluororubber, liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer and allyl glycidyl ether.

[0016] By adopting the above technical solution, this application uses pretreated fluororubber and EPDM rubber for compounding. The two produce a good synergistic effect, reducing the cost of the sealing ring while endowing it with excellent low-temperature resistance. This results in a low compression set in cold refrigerant environments, reducing cracking and maintaining good sealing stability. Since fluororubber and EPDM rubber have low compatibility, liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, and allyl glycidyl ether are introduced into the fluororubber. The resulting pretreated fluororubber exhibits good compatibility and dispersion uniformity with EPDM rubber, allowing for further cross-linking under the action of vulcanizing and cross-linking agents. This enhances the density of the cross-linked structure of the sealing ring, eliminating the need for additional compatibilizers and improving the low compression set of the sealing ring under low-temperature conditions, ensuring good sealing performance even after prolonged operation. The filler further reinforces the mechanical strength and wear resistance of the sealing ring. Plasticizers can improve the processing performance of each raw material in the system, further enhancing the overall performance of the resulting sealing ring. The sealing ring obtained in this application, when applied to the air conditioning system of new energy vehicles, exhibits good resistance to low-temperature refrigerants and maintains good long-term sealing stability and reliability.

[0017] Preferably, the pretreated fluororubber is prepared from the following raw materials in parts by weight:

[0018] 80-100 parts of fluororubber

[0019] 20-30 parts of liquid polyisoprene rubber

[0020] 8-12 parts of vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer

[0021] 5-8 parts of allyl glycidyl ether.

[0022] Preferably, the pretreated fluororubber is prepared by the following steps: mixing fluororubber, liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer and allyl glycidyl ether at a temperature of 120-130°C for 1-2 hours to obtain the pretreated fluororubber.

[0023] By adopting the above technical solution, this application uses a preferred amount of liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, and allyl glycidyl ether to mix with fluororubber, pretreating the fluororubber. Adding a silane copolymer with a vinyl long-chain structure and fluorinated side chains and an allyl glycidyl ether with vinyl and flexible ether segments to the fluororubber system can produce a good synergistic effect with the liquid polyisoprene rubber, interwoven and dispersed in the fluororubber system, improving the compatibility of the entire fluororubber system with EPDM rubber. Under the action of vulcanizing agents and crosslinking agents, the components can be uniformly mixed and fully crosslinked, improving the molecular structure flexibility and density of the obtained sealing ring, thereby improving the low compression deformation and sealing stability of the obtained sealing ring under low-temperature conditions. Mixing under optimal conditions can further improve the uniform mixing of the components, thereby improving the overall performance of the pretreated fluororubber.

[0024] Preferably, the filler is one or a combination of carbon black, calcium carbonate and talc.

[0025] By adopting the above technical solutions and selecting one or a combination of carbon black, calcium carbonate, and talc as fillers, the mechanical strength and wear resistance of the sealing ring can be significantly improved.

[0026] Preferably, the plasticizer is any one of paraffin oil, dioctyl phthalate, and dioctyl terephthalate.

[0027] By adopting the above technical solution and selecting any one of paraffin oil, dioctyl phthalate, and dioctyl terephthalate as a plasticizer, the flexibility and processing performance of the sealing ring can be effectively improved, making it less prone to cracking in low-temperature environments, thereby enhancing the overall stability and service life of the sealing ring.

[0028] Preferably, the crosslinking agent is composed of triallyl isocyanurate and tetraallylsilane in a weight ratio of (2-3):1.

[0029] By adopting the above technical solution, using triallyl isocyanurate and tetraallylsilane in a better weight ratio as crosslinking agents, it is possible to further crosslink with pretreated fluororubber and EPDM system, thereby further improving the low-temperature sealing performance of the prepared sealing ring.

[0030] Preferably, the vulcanizing agent is 2,4-di-tert-butyl peroxide and / or dicumyl peroxide.

[0031] By adopting the above technical solution and using 2,4-di-tert-butyl peroxide and / or di-diisopropylbenzene peroxide as a vulcanizing agent, the crosslinking density and vulcanization efficiency of the sealing ring can be effectively improved, thereby enhancing the mechanical strength and low-temperature resistance of the sealing ring.

[0032] Preferably, the antioxidant is one or a combination of antioxidant 445, antioxidant 4010, and antioxidant 4020.

[0033] By adopting the above technical solution, the above-mentioned anti-aging agent has good anti-aging performance, which can improve the sealing stability of the prepared sealing ring under long-term low-temperature refrigerant cycling conditions and extend the service life of the sealing ring.

[0034] Secondly, this application provides a method for preparing a low-pressure variable sealing ring for use in new energy air conditioners, employing the following technical solution:

[0035] A method for preparing a low-pressure variable sealing ring for use in new energy air conditioners includes the following steps:

[0036] S1. Mixing: Pretreated fluororubber, EPDM rubber, filler, plasticizer, crosslinking agent and antioxidant are mixed to obtain a compound;

[0037] S2, Slicing: Cool down to below 90℃, add vulcanizing agent to the mixture and knead, press and extrude, slice to obtain pre-made sheets;

[0038] S3. Compression molding: The preform is molded and vulcanized, then punched to obtain a low-pressure variable sealing ring.

[0039] By adopting the above technical solution and preparing it through mixing, slicing and molding, it has good operability and can produce low-pressure variable sealing rings with relatively low cost and excellent low-temperature adaptability, which are suitable for various working conditions of air conditioning systems in new energy vehicles.

[0040] Preferably, the mixing temperature in step S1 is 130-145℃, and the vulcanization temperature in step S3 is 170-180℃.

[0041] By adopting the above technical solutions, an optimal mixing temperature can effectively improve the compatibility and uniform dispersion of pretreated fluororubber and EPDM rubber, thereby enhancing the overall mechanical properties and low compression set of the sealing ring. An optimal vulcanization temperature allows the system to react fully, forming a stable network cross-linked structure, further improving the heat resistance and anti-aging properties of the sealing ring, ensuring good sealing performance even under high temperature, high pressure, and refrigerant environments.

[0042] In summary, this application includes at least one of the following beneficial technical effects:

[0043] 1. The composite use of pretreated fluororubber and EPDM rubber significantly improves the low-temperature resistance of the sealing ring. It is also compounded with fillers, plasticizers, crosslinking agents, vulcanizing agents and antioxidants. The sealing ring made in this way still maintains excellent elasticity and mechanical strength under low-temperature conditions in a refrigerant environment, and is not easily deformed or cracked after long-term use.

[0044] 2. By introducing liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, and allyl glycidyl ether into fluororubber, the pretreated fluororubber prepared has good compatibility and dispersion uniformity with EPDM rubber. It can further undergo cross-linking reaction under the action of vulcanizing agent and cross-linking agent, improving the cross-linking structure density of the sealing ring. The entire system does not require the addition of additional compatibilizer, improving the low compression deformation capacity of the prepared sealing ring under low temperature conditions, so that the sealing ring can maintain good sealing effect after long-term operation.

[0045] 3. Using triallyl isocyanurate and tetraallylsilane in a better weight ratio as crosslinking agents, they can be further crosslinked with pretreated fluororubber and EPDM systems, thereby further improving the low-temperature sealing performance of the prepared sealing ring. Detailed Implementation

[0046] The present application will be further described in detail below with reference to the embodiments.

[0047] The following are some of the sources and specifications of the raw materials used in this application. The raw materials used in the preparation examples and embodiments of this application can all be obtained commercially, including but not limited to the following models and manufacturers of raw materials. Raw materials with equivalent performance can also be used:

[0048] 1. Fluororubber: Chemours, USA FKM AL-300;

[0049] 2. EPDM rubber: Arlanx, 10660C;

[0050] 3. Liquid polyisoprene rubber: Manufacturer: Langbowan, molecular weight 30,000;

[0051] 4. Vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer: Sisbo Organosilicon, VF6960;

[0052] 5. Carbon black: N550 carbon black, particle size 20-80nm;

[0053] 6. Paraffin oil: Model KP6030.

[0054] Example of Pretreatment of Fluororubber

[0055] Preparation Example 1

[0056] Preparation Example 1 discloses a pretreated fluororubber, which is prepared by the following steps:

[0057] Using a two-roll mill, 8 kg of fluororubber, 2 kg of liquid polyisoprene rubber, 0.8 kg of vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, and 0.8 kg of allyl glycidyl ether were mixed at 120°C for 2 hours to obtain pretreated fluororubber.

[0058] Preparation Examples 2-3

[0059] The difference between Preparation Example 2-3 and Preparation Example 1 lies in the amount of raw materials used and the preparation conditions, as detailed in Table 1 below.

[0060] Table 1. Parameters for Preparation Examples 1-3

[0061]

[0062] Preparation of Comparative Example 1

[0063] The difference between Comparative Example 1 and Preparation Example 1 is that the liquid polyisoprene rubber was replaced with an equal amount of fluororubber, while the rest was the same as Preparation Example 1.

[0064] Preparation of Comparative Example 2

[0065] The difference between Comparative Example 2 and Preparation Example 1 is that vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer was replaced with vinyltrimethoxysilane in equal amounts, while the rest was the same as Preparation Example 1.

[0066] Preparation of Comparative Example 3

[0067] The difference between Comparative Example 2 and Preparation Example 1 is that allyl glycidyl ether was replaced with polyethylene glycol 800 in equal amounts, while the rest was the same as Preparation Example 1.

[0068] Preparation of Comparative Example 4

[0069] The difference between Comparative Example 4 and Preparation Example 1 is that allyl glycidyl ether was replaced in equal amounts with vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, while the rest was the same as Preparation Example 1.

[0070] Example

[0071] Example 1

[0072] Example 1 discloses a low-pressure variable sealing ring for use in new energy air conditioners, which is prepared by the following steps:

[0073] S1. Mixing: Using a two-roll mill, 5 kg of pretreated fluororubber, 4 kg of EPDM rubber, 2.5 kg of carbon black as filler, 0.5 kg of paraffin oil as plasticizer, 0.4 kg of triallyl isocyanurate as crosslinking agent and 0.1 kg of antioxidant 445 prepared in Example 1 were mixed at a mixing temperature of 130°C for 3 hours to obtain a compound.

[0074] S2, Slicing: Cool down to 89℃, add 0.3kg of 2,4-di-tert-butyl peroxide as a vulcanizing agent to the mixture obtained in step S1, mix and knead for 10 minutes, then press and extrude, slice, and obtain pre-made sheets.

[0075] S3. Compression molding: Place the preform into the mold of the molding vulcanizing machine, close the mold and perform compression vulcanization molding. Control the vulcanization temperature to 170℃ and vulcanize for 10 minutes. After taking it out, use a stamping device to punch off the scrap material to obtain the low-pressure variable sealing ring.

[0076] Example 2-3

[0077] The difference between Examples 2-3 and Example 1 lies in the amount of raw materials used and the preparation conditions, as detailed in Table 2 below.

[0078] Table 2 Parameter table for Examples 1-3

[0079]

[0080]

[0081] Example 4

[0082] The difference between Example 4 and Example 1 is that the crosslinking agent is different. The crosslinking agent in Example 4 is composed of triallyl isocyanurate and tetraallylsilane in a weight ratio of 2:1. Everything else is the same as in Example 1.

[0083] Example 5

[0084] The difference between Example 5 and Example 1 is that the crosslinking agent is different. The crosslinking agent in Example 5 is composed of triallyl isocyanurate and tetraallylsilane in a weight ratio of 3:1. Everything else is the same as in Example 1.

[0085] Comparative Example

[0086] Comparative Examples 1-4

[0087] The difference between Comparative Examples 1-4 and Example 1 is that the source of the pretreated fluororubber is different, as detailed in Table 3 below.

[0088] Table 3. Source of pretreated fluororubber for Comparative Examples 1-4

[0089] Comparative Example Pre-treated fluororubber source Comparative Example 1 Preparation of Comparative Example 1 Comparative Example 2 Preparation of Comparative Example 2 Comparative Example 3 Preparation of Comparative Example 3 Comparative Example 4 Preparation of Comparative Example 4

[0090] Comparative Example 5

[0091] The difference between Comparative Example 5 and Example 1 is that the pretreated fluororubber was replaced with an equal amount of fluororubber. The fluororubber was commercially available and came from the same source as the fluororubber in Preparation Example 1. Otherwise, it was the same as Example 1.

[0092] Performance testing

[0093] The performance of the sealing rings prepared in Examples 1-5 and Comparative Examples 1-5 was tested below: a low-pressure variable sealing ring with an inner diameter of 15 mm and a cross-sectional diameter of 1.8 mm was used as the test sample.

[0094] 1. Refrigerant compression deformation rate test:

[0095] The low-pressure variable seal ring was immersed in pressurized liquefied HFC-134a refrigerant for 72 hours. After removal, the compression deformation rate (unit: %) of the low-pressure variable seal ring was tested according to the test method in GB / T 7759-2015, and the test results were recorded.

[0096] 2. Low-temperature compression set test:

[0097] Place the low-pressure variable seal ring in a refrigerator at -40℃ for 72 hours. After removing it and restoring it to 25℃, test the compression deformation rate (unit: %) of the low-pressure variable seal ring according to the test method in GB / T7759-2015, observe whether the surface is cracked, and test and record the test results.

[0098] The following are the performance test data of the low-pressure variable seal rings of Examples 1-5 and Comparative Examples 1-5, as detailed in Table 4 below.

[0099] Table 4 Performance data of low-pressure variable seal rings in Examples 1-5 and Comparative Examples 1-5

[0100]

[0101] Based on Examples 1-3 and Comparative Examples 1-5, and referring to Table 4, it can be concluded that the sealing rings prepared using the pretreated fluororubber of this application exhibit good low-temperature stability against refrigerants. In Comparative Example 5, replacing the pretreated fluororubber with an equal amount of commercially available fluororubber significantly improved the refrigerant compression set and low-temperature compression set of the resulting sealing rings, and significant cracking occurred. This may be because the poor compatibility between fluororubber and EPDM rubber reduces the overall performance of the resulting sealing rings. Compared to Comparative Examples 1-4, Example 1 further optimized the pre-treated fluororubber by using liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, and allyl glycidyl ether for compounding and mixing with fluororubber. The resulting sealing ring exhibited significantly reduced cold media compression set and low-temperature compression set. In Comparative Examples 1-4, the dosage or composition of each component was changed, resulting in a decrease in the performance of the sealing ring. This may be because the synergistic effect of liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer, and allyl glycidyl ether was reduced, thereby decreasing the crosslinking performance of the fluororubber and EPDM rubber system, leading to a decrease in the performance of the resulting sealing ring, and some cracking also occurred.

[0102] Combining Examples 1-3 and Examples 4-5 with Table 4, it can be concluded that further optimization of the crosslinking agent's composition and ratio can further improve the low-compression performance of the prepared sealing ring. Compared with Example 1, the sealing rings prepared in Examples 4-5 show reduced refrigerant compression deformation rate and low-temperature compression deformation rate. This may be because the optimal weight ratio of triallyl isocyanurate and tetraallyl silane has a better synergistic effect, further improving the crosslinking performance of the system and thus further enhancing the structural density of the prepared sealing ring.

[0103] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A low-pressure variable sealing ring for use in new energy air conditioners, characterized in that, It is prepared from the following raw materials in parts by weight: 50-60 parts of pretreated fluororubber 30-40 parts EPDM rubber 25-35 parts of filler 5-10 parts plasticizer 4-8 parts of crosslinking agent 3-6 parts of vulcanizing agent Antioxidant 1-3 parts; the pretreated fluororubber is made from the following raw materials in parts by weight: 80-100 parts of fluororubber 20-30 parts of liquid polyisoprene rubber 8-12 parts of vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer 5-8 parts of allyl glycidyl ether; The pretreated fluororubber is prepared by the following steps: Pretreated fluororubber is prepared by mixing fluororubber, liquid polyisoprene rubber, vinyl dimethyl-terminated dimethyl-methyltrifluoropropyl polysiloxane copolymer and allyl glycidyl ether at a temperature of 120-130℃ for 1-2 hours. The crosslinking agent is composed of triallyl isocyanurate and tetraallylsilane in a weight ratio of (2-3):

1.

2. The low-pressure variable sealing ring for use in new energy air conditioners according to claim 1, characterized in that, The filler is one or a combination of carbon black, calcium carbonate and talc.

3. The low-pressure variable sealing ring for use in new energy air conditioners according to claim 1, characterized in that, The plasticizer is any one of paraffin oil, dioctyl phthalate, and dioctyl terephthalate.

4. The low-pressure variable sealing ring for use in new energy air conditioners according to claim 1, characterized in that, The vulcanizing agent is 2,4-di-tert-butyl peroxide and / or di-diisopropylbenzene peroxide.

5. A low-pressure variable sealing ring for use in new energy air conditioners according to claim 1, characterized in that, The antioxidant is one or a combination of antioxidant 445, antioxidant 4010, and antioxidant 4020.

6. A method for preparing a low-pressure variable sealing ring for use in new energy air conditioning as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Mixing: Pretreated fluororubber, EPDM rubber, filler, plasticizer, crosslinking agent and antioxidant are mixed to obtain a compound; S2, Slicing: Cool down to below 90℃, add vulcanizing agent to the mixture and knead, press and extrude, slice to obtain pre-made sheets; S3. Compression molding: The preform is molded and vulcanized, then punched to obtain a low-pressure variable sealing ring.

7. The method for preparing a low-pressure variable sealing ring for use in new energy air conditioning according to claim 6, characterized in that, The mixing temperature in step S1 is 130-145℃, and the vulcanization temperature in step S3 is 170-180℃.

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