Preparation method and application of silicone rubber

Abstract

The invention discloses a preparation method of silicone rubber, and belongs to the field of silicone rubber electrical insulating materials. By optimizing the components, the tracking resistance of the silicone rubber is greatly improved, the silicone rubber can pass 1A4.5 level, the mechanical property is not damaged, the flame retardance is improved, the synergistic catalytic activity of the silicone rubber is further improved by complexing the platinum-containing compound and the silane coupling agent and cooperating with the polysilazane, and the beneficial modification effect is achieved; the defects of poor compatibility, easy migration and failure and poor tracking resistance of a common silicone rubber organic tracking-resistant agent are overcome on the whole. Besides, the platinum-containing compound is subjected to a crosslinking reaction with the silicone rubber under the action of an electric arc to generate a compact ceramic-like protective layer, so that the tracking resistance and flame retardance of the silicone rubber are greatly improved, the failure caused by migration of an organic tracking-resistant tracking agent can be avoided, and the silicone rubber is convenient to purchase, simple in processing mode, convenient for industrial production and suitable for industrial production. The method has an important application prospect in the field of high-voltage insulation.

Description

Technical Field

[0001] The invention relates to the field of preparation of silicone rubber electrical insulating materials, and in particular to a preparation method of silicone rubber and application thereof. Background Art

[0002] The development of the power system has driven the continuous renewal of insulating materials. Silicone rubber has become one of the most promising and application-oriented insulating materials in the field of high-voltage insulating materials due to its excellent electrical insulation performance, weather resistance, flame retardancy, hydrophobicity and hydrophobic recovery. However, during the use of silicone rubber insulating materials, its surface will be polluted by dust, dew, fog, rain, etc. in the environment. Under the action of uneven strong electric fields, leakage current will be generated, forming intervals of dry bands, and further producing dry band arc discharge, resulting in the tracking and erosion of insulating materials (i.e., leakage tracking), causing the insulation failure of the material. Moreover, in recent years, the increasingly severe air pollution, frequent bad weather and the increasing operating voltage level of the power system have also made the working environment of insulating materials more severe, and power system failures caused by leakage tracking damage have become more common. Therefore, how to effectively improve the resistance to leakage tracking of silicone rubber is an important issue that needs to be solved in the development of silicone rubber high-voltage insulating materials.

[0003] In the prior art, the tracking resistance of silicone rubber is mainly improved by adding tracking resistance additives. Common tracking resistance agents include inorganic fillers such as aluminum trihydrate, magnesium hydroxide, boron nitride, or organic additives such as melamine cyanurate, nitrogen-containing silane coupling agents, such as the technical solutions described in patents with patent application numbers CN104130580A, US7851525B2, and CN104974530A. However, inorganic fillers are usually added in large amounts (more than 40wt%), which will greatly damage the mechanical properties and other properties of silicone rubber. Pure organic additives have poor compatibility with silicone rubber, there is a problem of poor dispersion, and small molecule additives are easy to migrate, all of which affect the performance stability of silicone rubber during long-term service and pose certain safety hazards. The production process of loaded additives is complicated, which is not conducive to expanded production. Studying a tracking-resistant silicone rubber can firstly solve the problem of loss of mechanical properties of silicone rubber due to the addition of a large amount of inorganic substances, and secondly solve the problem of unstable performance caused by poor compatibility of organic substances added alone with silicone rubber, and it is of great significance to facilitate large-scale production. Summary of the invention

[0004] Based on this, in order to solve the technical problem that the prior art silicone rubber has poor tracking resistance, the present invention provides a preparation method and application of tracking resistant silicone rubber, and the specific technical scheme is as follows:

[0005] A method for preparing silicone rubber, the method comprising the following steps:

[0006] Add the silicone rubber compound into the mixer and mix evenly at room temperature;

[0007] The silane coupling agent and the platinum-containing compound are uniformly mixed to obtain a mixture A;

[0008] Adding polysilazane into silicone rubber and kneading them evenly to obtain a mixture B;

[0009] The mixture A is added to the mixture B, and the mixture is kneaded evenly. Then, a vulcanizing agent is added and kneaded, and then the mixture is subjected to a first vulcanization treatment and a second vulcanization treatment to obtain a silicone rubber with excellent anti-tracking performance and excellent flame retardant performance.

[0010] Furthermore, the structural formula of the silane coupling agent is at least one of the following:

[0011]

[0012] R5CH2CH2CH2Si(OR3) 3-i (R4) I ;

[0013] Where R1, R2 are -H, -(CH2) n CH3, -Ph or -(CH2) n NHC m H 2m+1 , n and m are integers of 0 to 8; R3 and R4 are -CH3 or -CH2CH3; i is 0 to 2; R5 is -NHCONR1R2 or -NHC(=NH)NR1R2.

[0014] Furthermore, the platinum-containing compound is at least one of Custer's olefin siloxane complex, Custer's tetramethyldisiloxane complex, Custer's isopropanol solution or Custer's tetrahydrofuran solution.

[0015] Furthermore, the concentration of platinum in the pharmaceutical specification of the platinum-containing compound is 2000ppm to 4000ppm.

[0016] Furthermore, the amount of the platinum-containing compound added is 0.2 to 0.6 times the amount of the silane coupling agent added.

[0017] Furthermore, the structural formula of the polysilazane is at least one of the following:

[0018] (R1R2Si-NH) x (R3R4Si-NH) y , x and y are integers of 1-300; wherein R1, R2, R3, and R4 are independently CH3, C m H 2m+1, CH=CH2 and (CH2) m Any one of CH=CH2, and at least one of R1, R2, R3, and R4 is CH=CH2 or (CH2)mCH=CH2, and m is selected from an integer between 1 and 7; the molecular weight of the polysilazane is 1000 to 9000.

[0019] Furthermore, the temperature of the first vulcanization treatment is 160° C. to 170° C., and the time of the first vulcanization treatment is 0.1 h to 0.5 h; the temperature of the second vulcanization treatment is 170° C. to 210° C., and the time of the second vulcanization treatment is 2 h to 5 h.

[0020] Furthermore, the mass ratio of the polysilazane to the silicone rubber is (1-5): (200-250).

[0021] Furthermore, the mass ratio of the silane coupling agent to the silicone rubber is (1-5): (200-250).

[0022] Furthermore, the mass ratio of the vulcanizing agent to the silicone rubber is (3-7):(200-250).

[0023] Compared with the prior art, this application has the following beneficial effects:

[0024] 1. The present invention overcomes the disadvantage of high filling amount of commonly used silicone rubber inorganic anti-tracking agent, and can achieve efficient modification of silicone rubber anti-tracking performance. A small amount of addition can greatly improve the anti-tracking performance of silicone rubber, and can make silicone rubber pass 1A4.5 grade; a small amount of addition can improve the flame retardant performance of silicone rubber; and does not damage its mechanical properties.

[0025] 2. The present invention overcomes the shortcomings of poor compatibility and easy migration failure of commonly used organic tracking agents for silicone rubber, and can ensure the stable performance of silicone rubber during long-term service. At the same time, the platinum-containing compound and the silane coupling agent are complexed and synergistic with polysilazane to further improve their synergistic catalytic activity, achieving a beneficial modification effect.

[0026] 3. The raw materials of the present invention are cheap and readily available, the preparation process is simple, and large-scale production can be easily achieved, thus having a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention can be further understood from the following description in conjunction with the accompanying drawings. The components in the figures are not necessarily drawn to scale, but the emphasis is placed on illustrating the principles of the embodiments. In different views, the same reference numerals designate corresponding parts.

[0028] Figure 1 This is a sample photo of the sample after the tracking test of Example 1;

[0029] Figure 2 This is a schematic diagram of the sample after the vertical combustion test of the sample in Example 1;

[0030] Figure 3 This is a schematic diagram of the sample of Comparative Example 1 after the vertical combustion test;

[0031] Figure 4 This is a sample photo of the sample of Comparative Example 1 after the tracking test; DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0034] A method for preparing silicone rubber in one embodiment of the present invention comprises the following steps:

[0035] Add the silicone rubber compound into the mixer and mix evenly at room temperature;

[0036] The silane coupling agent and the platinum-containing compound are uniformly mixed to obtain a mixture A;

[0037] Adding polysilazane into silicone rubber and kneading them evenly to obtain a mixture B;

[0038] The mixture A is added to the mixture B, and the mixture is kneaded evenly. Then, a vulcanizing agent is added and kneaded, and then the mixture is subjected to a first vulcanization treatment and a second vulcanization treatment to obtain a silicone rubber with excellent anti-tracking performance.

[0039] In one embodiment, the structural formula of the silane coupling agent is at least one of the following:

[0040]

[0041] R5CH2CH2CH2Si(OR3) 3-i (R4) I ;

[0042] Where R1, R2 are -H, -(CH2) nCH3, -Ph or -(CH2) n NHC m H 2m+1 , n and m are integers of 0 to 8; R3 and R4 are -CH3 or -CH2CH3; i is 0 to 2; R5 is -NHCONR1R2 or -NHC(=NH)NR1R2.

[0043] In one embodiment, the platinum-containing compound is at least one of Custer's olefin siloxane complex, Custer's tetramethyldisiloxane complex, Custer's isopropanol solution or Custer's tetrahydrofuran solution.

[0044] In one embodiment, the concentration of platinum in the pharmaceutical specification of the platinum-containing compound is 2000ppm to 4000ppm.

[0045] In one embodiment, the amount of the platinum-containing compound added is 0.2 to 0.6 times the amount of the silane coupling agent added.

[0046] In one embodiment, the structural formula of the polysilazane is at least one of the following:

[0047] (R1R2Si-NH) x (R3R4Si-NH) y , x and y are integers of 1-300; wherein R1, R2, R3, and R4 are independently CH3, C m H 2m+1 , CH=CH2 and (CH2) m Any one of CH=CH2, and at least one of R1, R2, R3, and R4 is CH=CH2 or (CH2)mCH=CH2, and m is selected from an integer between 1 and 7; the molecular weight of the polysilazane is 1000 to 9000.

[0048] In one embodiment, the silane coupling agent, the polysilazane and the platinum-containing compound are added simultaneously.

[0049] In one embodiment, the vulcanizing agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane.

[0050] In one embodiment, the temperature of the first vulcanization treatment is 160°C to 170°C, and the time of the first vulcanization treatment is 0.1h to 0.5h; the temperature of the second vulcanization treatment is 170°C to 210°C, and the time of the second vulcanization treatment is 2h to 5h.

[0051] In one of the embodiments, the mass ratio of the polysilazane to the silicone rubber is (1-5): (200-250).

[0052] Furthermore, the mass ratio of the silane coupling agent to the silicone rubber is (1-5): (200-250).

[0053] Furthermore, the mass ratio of the vulcanizing agent to the silicone rubber is (3-7):(200-250).

[0054] In one of the embodiments, the silicone rubber with excellent anti-tracking performance is used in the preparation of flame retardant materials.

[0055] In the above scheme, platinum and silane coupling agent are complexed and effectively enhance the synergistic catalytic activity of platinum and silane and their uniform and stable dispersion in silicone rubber. On the one hand, the complexation of platinum and silane coupling agent enhances its synergistic catalytic effect. On the other hand, when polysilazane is mixed with silicone rubber, its surface adsorbs silicone rubber molecular chains through hydrogen bonding, which not only improves the mechanical properties of silicone rubber, but also facilitates platinum and alkane-containing coupling agent to catalyze the cross-linking reaction of silicone rubber molecular chains under arc discharge, forming a dense protective layer to avoid arc erosion. Therefore, the direct addition type silicone rubber prepared by the present invention can greatly enhance its resistance to leakage current tracking and flame retardancy. On the whole, it can solve the technical problem of poor resistance to leakage current tracking of silicone rubber in the prior art.

[0056] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0057] Embodiment 1:

[0058] A method for preparing silicone rubber comprises the following steps:

[0059] 100 parts by mass of a silicone rubber compound having a white carbon black content of 27 wt % was put into an open mixer, and 0.7 parts by mass of polysilazane was added to the silicone rubber to obtain a mixture A.

[0060] 0.7 parts by mass of 3-aminopropyltrimethoxysilane (AS) and 0.4 parts by mass of a platinum-containing catalyst, Custer, having a platinum content of 12 ppm (Pt-AS), were mixed to obtain a mixture B.

[0061] The mixture B is added to the mixture A and kneaded evenly, and then 1.5 parts by mass of 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane is added and kneaded, followed by a first vulcanization treatment at 165° C. for 20 min and a second vulcanization treatment at 180° C. for 4 h to obtain a silicone rubber sample 1 with excellent anti-tracking performance.

[0062] Embodiment 2:

[0063] A method for preparing silicone rubber comprises the following steps:

[0064] 100 parts by mass of a silicone rubber compound having a white carbon black content of 27 wt % was put into an open mixer, and 1 part by mass of polysilazane was added to the silicone rubber to obtain a mixture A.

[0065] 1 part by mass of 3-aminopropyltrimethoxysilane (AS) was mixed with 0.4 parts by mass of a platinum-containing catalyst having a castellated platinum content of 12 ppm (Pt-AS) to obtain a mixture B.

[0066] The mixture B is added to the mixture A and kneaded evenly, and then 1.5 parts by mass of 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane is added and kneaded, followed by a first vulcanization treatment at 165° C. for 20 min and a second vulcanization treatment at 180° C. for 4 h to obtain a silicone rubber sample 1 with excellent anti-tracking performance.

[0067] Comparative Example 1:

[0068] 100 parts by mass of a silicone rubber compound having a white carbon black content of 27 wt% was added to an open mixing mill, and then 1.5 parts by mass of 2,5-dimethyl-2,5-di-tert-butyl peroxide was added and mixed evenly. The first vulcanization treatment was performed at 165° C. for 20 minutes, and the second vulcanization treatment was performed at 180° C. for 4 hours to obtain a comparative sample 1.

[0069] Comparative Example 2:

[0070] 100 parts by mass of a silicone rubber compound having a white carbon black content of 27 wt % was put into an open mixer, and 1 part by mass of polysilazane was added to the silicone rubber to obtain a mixture A.

[0071] Then, 1.5 parts by mass of 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane was added to A, mixed evenly, and subjected to a first vulcanization treatment at 165° C. for 20 min, and then subjected to a second vulcanization treatment at 180° C. for 4 h, to obtain comparative sample 2.

[0072] The samples of Examples 1 to 2 and the comparative samples of Comparative Examples 1 to 2 were subjected to performance analysis, wherein the tracking resistance test of the silicone rubber samples was conducted in accordance with GB / T6553-2003. The constant voltage method was adopted, and the test voltage was 4.5 kV. The endpoint judgment used the "end point judgment method A" in the test method: when the current passing through the sample is greater than 60 mA, it is regarded as a tracking breakdown. The combustion performance of the silicone rubber sample was determined in accordance with GBT 10707-2008, and the vertical combustion and limiting oxygen index were determined. The results are shown in Table 1 below.

[0073] Table 1: Performance test results

[0074]

[0075] From the data analysis in Table 1, it can be seen that the comparative samples of Comparative Examples 1 to 2 cannot pass the 1A4.5 level tracking resistance test, indicating that the silicone rubber cannot pass the tracking resistance test without adding additives or adding polysilazane alone, and the flame retardant performance is poor. The samples of Examples 1 to 2 can pass the 1A4.5 level tracking resistance test; if the silicone rubber of Examples 1 to 2 is subjected to a flame retardant test, its vertical combustion level can be improved to V1, and the limiting oxygen index can reach 29.5-29.7%. It shows that the preparation method of the tracking resistance silicone rubber of Examples 1 to 2 can effectively improve the tracking resistance and flame retardant performance of silicone rubber.

[0076] like Figures 1 to 4 As shown, Figure 1 This is a schematic diagram of the sample after the tracking test of the sample in Example 1; Figure 2 This is a schematic diagram of samples for the flame retardancy vertical burning test of Example 1; Figure 3 This is a schematic diagram of the sample of Comparative Example 1 after the vertical combustion test; Figure 4 Schematic diagram of the sample after the tracking resistance test of the sample in comparative example 1. The test results of the sample in embodiment 2 are similar to those of the sample in embodiment 1, which will not be repeated here. The comparative sample in comparative example 2 is similar to that in comparative example 1, which will not be repeated here. Figure 2 and Figure 3 It can be seen that the flame retardancy of the sample in Example 1 is good, and the flame retardancy of the sample in Comparative Example 1 is poor. Figure 1 and Figure 4 It can be seen that Example 1 has good tracking resistance, while Comparative Example 1 has poor tracking resistance, which again illustrates that after the components are optimized in the present application, the migration resistance, tracking resistance and flame retardancy can be coordinated and made better and more stable.

[0077] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing silicone rubber, characterized in that: The preparation method comprises the following steps: Add the silicone rubber compound into the mixer and mix evenly at room temperature; The silane coupling agent and the platinum-containing compound are uniformly mixed to obtain a mixture A; Adding polysilazane into silicone rubber and kneading them evenly to obtain a mixture B; The mixture A is added to the mixture B, and the mixture is kneaded evenly. Then, a vulcanizing agent is added and kneaded, and then the mixture is subjected to a first vulcanization treatment and a second vulcanization treatment to obtain a silicone rubber with excellent anti-tracking performance.

2. The preparation method according to claim 1, characterized in that: The structural formula of the silane coupling agent is at least one of the following: R5CH2CH2CH2Si(OR3) 3-i (R4) I ; Where R1, R2 are -H, -(CH2) n CH3, -Ph or -(CH2) n NHC m H 2m+1 , n and m are integers of 0 to 8; R3 and R4 are -CH3 or -CH2CH3; i is 0 to 2; R5 is -NHCONR1R2 or -NHC(=NH)NR1R2.

3. The preparation method according to claim 1, characterized in that: The platinum-containing compound is at least one of Custer's olefin siloxane complex, Custer's tetramethyl disiloxane complex, Custer's isopropanol solution or Custer's tetrahydrofuran solution.

4. The preparation method according to claim 4, characterized in that: The platinum concentration of the platinum-containing compound product specification is 2000ppm to 4000ppm.

5. The preparation method according to claim 1, characterized in that: The amount of the platinum-containing compound added is 0.2 to 0.6 times the amount of the silane coupling agent added.

6. The preparation method according to claim 1, wherein the structural formula of the polysilazane is at least one of the following: (R1R2Si-NH) x (R3R4Si-NH) y , x and y are both integers from 1 to 300; wherein, R1, R2, R3, and R4 all independently represent CH3, C m H 2m+1 , CH=CH2 and (CH2) m Any one of CH=CH2, and at least one of R1, R2, R3, and R4 is CH=CH2 or (CH2)mCH=CH2, and m is selected from an integer between 1 and 7; the molecular weight of the polysilazane is 1000 to 9000.

7. The preparation method according to claim 1, characterized in that: The temperature of the first vulcanization treatment is 160° C. to 170° C., and the time of the first vulcanization treatment is 0.1 h to 0.5 h; the temperature of the second vulcanization treatment is 170° C. to 210° C., and the time of the second vulcanization treatment is 2 h to 5 h.

8. The preparation method according to claim 1, characterized in that: The mass ratio of the polysilazane to the silicone rubber is (1-5): (200-250).

9. The preparation method according to claim 1, characterized in that: The mass ratio of the silane coupling agent to the silicone rubber is (1-5): (200-250).

10. The preparation method according to claim 1, characterized in that: The mass ratio of the vulcanizing agent to the silicone rubber is (3-7):(200-250).

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