Low-temperature-resistant perfluoroether elastomer and preparation method thereof

Abstract

The invention discloses a low-temperature-resistant perfluoroether elastomer and a preparation method thereof. The perfluoroether elastomer is mainly prepared by pressurizing, banburying and mixing the following components in parts by mass: 100 parts of perfluoroether rubber, 0-50 parts of reinforcing filler, 0.3-2 parts of vulcanizing agent, 1-6 parts of accelerant and 1-15 parts of fluorosilicone oil, the fluorosilicone oil is formed by carrying out chain extension on vinyl fluorine-containing polysiloxane through hydrogen-terminated silicone oil. According to the low-temperature-resistant perfluoroether elastomer and the preparation method thereof provided by the invention, on the basis of existing perfluoroether rubber, the fluorosilicone oil is added through pressurized banburying, and after primary or secondary vulcanization, the low-temperature brittleness temperature of the low-temperature-resistant perfluoroether elastomer has a relatively good floating effect, and the influence of liquid resistance is relatively small, so that wider application is realized.

Description

Technical Field

[0001] The invention relates to the technical field of fluororubber, and in particular to a low-temperature resistant perfluoroether elastomer and a preparation method thereof. Background Art

[0002] Perfluoroether rubber refers to a polymer elastomer composed of tetrafluoroethylene, perfluoromethyl vinyl ether and vulcanization point monomers. In the molecular structure of perfluororubber, the bond energy of the CF bond (435-485 kJ / mol) is large, and the covalent radius of the fluorine atom (0.064 nm) is equivalent to half the length of the CC bond, and the CC segment is well protected by the fluorine atom. Therefore, perfluororubber has ultra-high chemical stability and thermal stability, and is the best medium-resistant performance among all elastomers at present. It can be widely used in aerospace, semiconductors, machinery, petrochemicals and other harsh environments that require resistance to special media such as lipids, amines, ketones, etc.

[0003] However, the existing perfluoroether rubber has a prominent disadvantage: its low temperature performance is too poor (generally Tg is not less than -2°C), which is far from meeting the market's performance requirements, especially in aviation and aerospace. Silicone has very good low temperature performance, generally reaching minus 40 to 60 degrees Celsius, so it is usually introduced into organic fluorine by introducing organic silane segments or using it in combination with silicone rubber to achieve the purpose of reducing low temperature performance. However, since silicone rubber and fluororubber are completely incompatible, the cross-linking agent and cross-linking mechanism are completely different, it is difficult to add and form a stable cross-network structure. At the same time, since silicone has poor liquid resistance, introducing silicone to change the low temperature resistance of organic fluororubber often greatly damages the liquid resistance of organic fluororubber.

[0004] Therefore, how to improve the low temperature resistance of fluororubber while retaining its superior high temperature liquid resistance to the greatest extent has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a low-temperature resistant perfluoroether elastomer and a preparation method thereof. On the basis of the existing perfluoroether rubber, fluorosilicone oil is added through pressurized mixing, and after one or two vulcanizations, the low-temperature brittle temperature is better reduced, while the liquid resistance is less affected, thereby achieving a wider range of applications.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a low-temperature resistant perfluoroether elastomer, which is mainly formed by pressurized banburying and mixing of the following components in parts by mass: 100 parts of perfluoroether rubber, 0 to 50 parts of reinforcing filler, 0.3 to 2 parts of vulcanizing agent, 1 to 6 parts of accelerator, and 1 to 15 parts of fluorosilicone oil; the fluorosilicone oil is formed by chain extension of vinyl fluorine-containing polysiloxane through terminal hydrogen silicone oil.

[0007] Furthermore, the structural formula of the vinyl fluorinated polysiloxane is as follows:

[0008]

[0009] Wherein, x, y, z are all integers and satisfy the relationship: x+y+z=10-10000; viscosity is 50-500cp;

[0010] The structural formula of the hydrogen-terminated silicone oil is as follows:

[0011]

[0012] Wherein, m and n are both integers and satisfy the relationship: m+n=10-1000, and the viscosity is 1-100 cp.

[0013] The reaction equation of vinyl fluorinated polysiloxane and hydrogen-terminated silicone oil with platinum catalyst is as follows:

[0014] The viscosity of the fluorosilicone oil is 500-5000cp.

[0015] Furthermore, when the fluorosilicone oil is prepared, the vinyl content (n Vi ) and the content of silicon-hydrogen bonds in hydrogen-terminated silicone oil (n Si-H ) is 10:1 to 5:1; the catalyst used is a platinum catalyst, and the amount of the catalyst is 10 to 100 ppm of the mass of the fluorosilicone oil. It is ensured that no insoluble cross-linked polymer is formed, and the fluorosilicone oil contains excessive vinyl to participate in the grafting reaction of the fluororubber raw rubber.

[0016] Furthermore, the perfluoroether rubber is a terpolymer of tetrafluoroethylene, perfluoromethyl vinyl ether and perfluoroolefin ether.

[0017] Furthermore, the reinforcing filler is one or a mixture of calcium silicate, carbon black, barium sulfate, diatomaceous earth, and silica powder. The reinforcing filler has a certain reinforcing effect on one hand, and on the other hand, it can also achieve the purpose of improving process performance, improving the heat resistance and hardness of the product, reducing compression permanent deformation and reducing costs.

[0018] Furthermore, the vulcanizing agent is a peroxide vulcanizing agent, including a vulcanizing agent di-2,5 or a vulcanizing agent DCP. If it is a high temperature perfluoroether rubber, the vulcanizing agent is generally a perfluoroalkane containing vinyl groups at both ends, such as CH2CH(CF2)6CHCH2.

[0019] Furthermore, the accelerator is one of TAIC and TAC or a mixture of several thereof.

[0020] A method for preparing a low-temperature resistant perfluoroether elastomer, the method mainly comprising the following steps:

[0021] 1) Mix appropriate amounts of reinforcing filler, vulcanizing agent, accelerator and fluorosilicone oil for later use;

[0022] 2) Add perfluoroether rubber to the internal mixer and plasticize for 2 to 3 minutes, turn on the cooling water, add the spare material and mix for 3 to 5 minutes, then transfer to the open mixer and thinly pass 5 to 10 times, cool the sheet and leave it for 20 to 24 hours, then re-refine the sheet and cool it to obtain the finished product.

[0023] In the preparation method provided by the present invention, under the action of a peroxide curing agent, a free radical crosslinking reaction occurs between perfluoroether rubber segments. The peroxide is decomposed by heating to generate free radicals, which then absorb H on tertiary carbon atoms in the polymer chain to form polymer free radicals, which form crosslinking bonds directly or through the mediation of a free radical scavenger (accelerator).

[0024] The beneficial effect of the present invention is that compared with the prior art, the present invention avoids physically mixing inactive or low-activity organic silanes to improve the low-temperature flexibility of perfluoroether, greatly reducing the physical and mechanical properties and excellent medium tolerance. The present invention provides a low-temperature resistant perfluoroether elastomer and a preparation method thereof, by introducing fluorosilicone oil into perfluoroether rubber, and coordinating with a vulcanizer, an accelerator, etc., the fluorosilicone oil contains vinyl groups, which can react with the perfluoroether rubber segment under the action of free radicals, and the fluorosilicone oil is grafted onto the perfluoroether rubber segment to form a polymer alloy. The fluorosilicone oil segment has excellent low-temperature flexibility and good medium resistance. The formed block polymer alloy improves the low-temperature resistance of the perfluoroether rubber while retaining the liquid resistance of the perfluoroether rubber. DETAILED DESCRIPTION

[0025] The present invention is further described below by specific examples, but these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0026] Example 1

[0027] The preparation method of fluorosilicone oil in this embodiment is as follows:

[0028] 100 parts by weight of vinyl fluorinated polysiloxane (vinyl content 6-8%) with a viscosity of 335 cp at 25°C, 20 parts by weight of hydrogen-terminated silicone oil with a viscosity of 50 cp at 25°C, and 1 part of a Castell platinum catalyst with a platinum content of 1000 ppm were mixed under vacuum to obtain a fluorinated silicone oil with a viscosity of 2050 cp at 25°C. The vinyl content (n Vi ) and the content of silicon-hydrogen bonds in hydrogen-terminated silicone oil (n Si-H) is 8:1; the content of metal platinum in fluorosilicone oil is 30ppm.

[0029] The preparation method of the low-temperature resistant perfluoroether elastomer in this embodiment is as follows: 15 parts of diatomaceous earth, 1.5 parts of vulcanizing agent di-2,5, 3 parts of accelerator TAIC, and 5 parts of fluorosilicone oil are mixed and set aside by weight; 100 parts of perfluoroether rubber are added to an internal mixer, plasticized for 2 to 3 minutes, the cooling water is turned on, the reserved material is added and mixed for 3 to 5 minutes, and then transferred to an open mixer for thinning 5 to 10 times, the sheets are cooled and parked for 20 to 24 hours, and the sheets are re-refined and cooled to obtain the finished product.

[0030] Example 2

[0031] The preparation method of fluorosilicone oil in this embodiment is the same as that in Example 1.

[0032] The preparation method of the low-temperature resistant perfluoroether elastomer in this embodiment is as follows: 15 parts of diatomaceous earth, 1.8 parts of vulcanizing agent di-2,5, 3 parts of accelerator TAIC, and 8 parts of fluorosilicone oil are mixed by weight and set aside; 100 parts of perfluoroether rubber are added to an internal mixer, plasticized for 2 to 3 minutes, the cooling water is turned on, the reserved material is added and mixed for 3 to 5 minutes, and then transferred to an open mixer and thinned for 5 to 10 times, the sheets are cooled and parked for 20 to 24 hours, and the sheets are re-refined and cooled to obtain the finished product.

[0033] Example 3

[0034] The preparation method of fluorosilicone oil in this embodiment is the same as that in Example 1.

[0035] The preparation method of the low-temperature resistant perfluoroether elastomer in this embodiment is as follows: 15 parts of diatomaceous earth, 2 parts of vulcanizing agent di-2,5, 3 parts of accelerator TAIC, and 12 parts of fluorosilicone oil are mixed by weight and set aside; 100 parts of perfluoroether rubber are added to an internal mixer, plasticized for 2 to 3 minutes, cooling water is turned on, and the reserved material is added and mixed for 3 to 5 minutes, then transferred to an open mixer and thinned for 5 to 10 times, the sheets are cooled and parked for 20 to 24 hours, and the sheets are re-refined and cooled to obtain the finished product.

[0036] Example 4

[0037] The preparation method of fluorosilicone oil in this embodiment is as follows:

[0038] 100 parts by weight of vinyl fluorinated polysiloxane with a viscosity of 335 cp at 25°C, 25 parts by weight of hydrogen-terminated silicone oil with a viscosity of 50 cp at 25°C, and 1 part of a Castell platinum catalyst with a platinum content of 1000 ppm are mixed under vacuum to obtain a fluorinated silicone oil with a viscosity of 2050 cp at 25°C. The vinyl content (n Vi ) and the content of silicon-hydrogen bonds in hydrogen-terminated silicone oil (n Si-H) is 5:1; the content of metallic platinum in the fluorosilicone oil is 25ppm.

[0039] The preparation method of the low-temperature resistant perfluoroether elastomer in this embodiment is as follows: 15 parts of diatomaceous earth, 1.5 parts of vulcanizing agent di-2,5, 3 parts of accelerator TAIC, and 5 parts and 3 parts of fluorosilicone oil are mixed and set aside; 100 parts of perfluoroether rubber are added to an internal mixer, plasticized for 2 to 3 minutes, the cooling water is turned on, the reserved material is added and mixed for 3 to 5 minutes, and then transferred to an open mixer and thinned for 5 to 10 times, the sheet is cooled and parked for 20 to 24 hours, and the sheet is re-refined and cooled to obtain the finished product.

[0040] Example 5

[0041] The preparation method of fluorosilicone oil in this embodiment is as follows:

[0042] 100 parts by weight of vinyl fluorinated polysiloxane with a viscosity of 335 cp at 25°C, 25 parts by weight of hydrogen-terminated silicone oil with a viscosity of 50 cp at 25°C, and 1 part of a Castell platinum catalyst with a platinum content of 1000 ppm are mixed under vacuum to obtain a fluorinated silicone oil with a viscosity of 2050 cp at 25°C. The vinyl content (n Vi ) and the content of silicon-hydrogen bonds in hydrogen-terminated silicone oil (n Si-H ) is 5:1; the content of metallic platinum in the fluorosilicone oil is 25ppm.

[0043] The preparation method of the low-temperature resistant perfluoroether elastomer in this embodiment is as follows: 15 parts of diatomaceous earth, 1.5 parts of vulcanizing agent di-2,5, 2.5 parts of CH2CH(CF2)6CHCH2, and 5 parts of fluorosilicone oil are mixed and set aside; 100 parts of perfluoroether rubber are added to an internal mixer, plasticized for 2 to 3 minutes, the cooling water is turned on, the reserved material is added and mixed for 3 to 5 minutes, and then transferred to an open mixer and thinned for 5 to 10 times, the sheet is cooled and parked for 20 to 24 hours, and the sheet is re-refined and cooled to obtain the finished product.

[0044] Comparative Example 1

[0045] The preparation method of perfluoroether elastomer is as follows: according to the weight parts, 15 parts of diatomaceous earth, 1.5 parts of vulcanizing agent di-2,5, and 3 parts of accelerator TAIC are added; 100 parts of perfluoroether rubber are added into an internal mixer, and plasticized for 2 to 3 minutes, cooling water is turned on, and the reserved material is added and mixed for 3 to 5 minutes, and then transferred to an open mixer and thinned for 5 to 10 times, the sheet is cooled and parked for 20 to 24 hours, and the sheet is re-refined and cooled to obtain the finished product.

[0046] Comparative Example 2

[0047] According to weight proportions, 15 parts of diatomaceous earth, 1.5 parts of di-2,5 vulcanizing agent and 2.5 parts of CH2CH(CF2)6CHCH2 are mixed and set aside; 100 parts of perfluoroether rubber are added into an internal mixer, and plasticized for 2 to 3 minutes. The cooling water is turned on, and the reserved material is added and mixed for 3 to 5 minutes. Then, the mixture is transferred to an open mixer and thinned for 5 to 10 times. The slices are cooled and parked for 20 to 24 hours, and the slices are returned to be cooled to obtain the finished product.

[0048] The elastomers obtained in the above Examples 1-5 were sampled according to relevant testing standards (the first stage vulcanization of the test piece was 165°C x 20 minutes, and the second stage vulcanization was 230°C 24h) and performance tests were performed. The results are shown in Table 1 below.

[0049]

[0050] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A low temperature resistant perfluoroether elastomer, characterized in that: The perfluoroether elastomer is mainly prepared by hot kneading and mixing the following components in parts by weight: 100 parts of perfluoroether rubber, 0-50 parts of reinforcing filler, 0.3-2 parts of vulcanizing agent, 1-6 parts of accelerator, and 1-15 parts of fluorosilicone oil; the fluorosilicone oil is prepared by chain extension of vinyl fluorine-containing polysiloxane through terminal hydrogen silicone oil.

2. A low temperature resistant perfluoroether elastomer according to claim 1, characterized in that: The structural formula of the vinyl fluorine-containing polysiloxane is as follows: Wherein, x, y, z are all integers and satisfy the relationship: x+y+z=10-10000; The structural formula of the hydrogen-terminated silicone oil is as follows: Wherein, m and n are both integers and satisfy the relationship: m+n=10-1000; The reaction equation of the vinyl fluorinated polysiloxane and the hydrogen-terminated silicone oil is as follows:

3. A low temperature resistant perfluoroether elastomer according to claim 1 or 2, characterized in that: When the fluorosilicone oil is prepared, the vinyl content (n Vi ) and the content of silicon-hydrogen bonds in hydrogen-terminated silicone oil (n Si-H ) is in a molar ratio of 10:1 to 5:1; the catalyst used is a platinum catalyst, and the amount of the catalyst used accounts for 10 to 100 ppm of the mass of the fluorosilicone oil.

4. A low temperature resistant perfluoroether elastomer according to claim 1, characterized in that: The perfluoroether rubber is a terpolymer of tetrafluoroethylene, perfluoromethyl vinyl ether and perfluoroolefin ether.

5. The low temperature resistant perfluoroether elastomer according to claim 1, characterized in that: The reinforcing filler is one of calcium silicate, carbon black, barium sulfate, diatomaceous earth and silica powder or a mixture of several of them.

6. A low temperature resistant perfluoroether elastomer according to claim 1, characterized in that: The vulcanizing agent is a peroxide vulcanizing agent, including a vulcanizing agent bis-2,5 or a vulcanizing agent DCP.

7. A low temperature resistant perfluoroether elastomer according to claim 1, characterized in that: The vulcanizing agent is a perfluoroalkane having two terminal groups containing vinyl groups, including: CH2CH(CF2)6CHCH2.

8. The low temperature resistant perfluoroether elastomer according to claim 1, characterized in that: The accelerator is one of TAIC and TAC or a mixture of several of them.

9. A method for preparing a low-temperature resistant perfluoroether elastomer as claimed in claim 1, characterized in that: The preparation method mainly comprises the following steps: 1) Mix appropriate amounts of reinforcing filler, vulcanizing agent, accelerator and fluorosilicone oil for later use; 2) Add perfluoroether rubber to the internal mixer and plasticize for 3 to 10 minutes, turn on the cooling water, add the spare material and mix for 3 to 5 minutes, then transfer to the open mixer and thinly pass 5 to 10 times, cool the sheet and leave it for 20 to 24 hours, re-refine the sheet and cool it to obtain the finished product.

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