Low-temperature-resistant high-molecular compatibilizer as well as preparation method and application thereof

Abstract

The invention relates to a low-temperature-resistant high-molecular compatibilizer as well as a preparation method and application thereof, and belongs to the technical field of high-molecular compounds obtained by reactions except for carbon-carbon unsaturated bonds. The low-temperature-resistant high-molecular compatibilizer disclosed by the invention is obtained by carrying out esterification reaction on carboxyl-containing acrylate rubber and hydroxyl-terminated nitrile rubber. The low-temperature-resistant high-molecular compatibilizer can effectively enhance the compatibility between nitrile rubber and acrylate rubber, so that the nitrile rubber / acrylate composite rubber elastomer is endowed with good mechanical properties, and meanwhile, the low-temperature performance and the oil resistance of the nitrile rubber / acrylate composite rubber elastomer can be remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer compounds obtained by reactions other than carbon-carbon unsaturated bonds, and in particular to a low-temperature resistant polymer compatibilizer and a preparation method and application thereof. Background Art

[0002] Transformer is an electrical device used for mutual conversion of electric energy. It is mainly divided into dry-type transformer and oil-immersed transformer according to the cooling method. Compared with dry-type transformer, oil-immersed transformer not only has better thermal conductivity, but also has good weather resistance, and can work normally under harsh environmental conditions. Moreover, the transformer oil in the oil-immersed transformer can be used as an insulating medium, which not only realizes the functions of heat dissipation and electrical insulation of the equipment, but also plays the role of arc extinguishing when the transformer fails. However, the oil leakage problem caused by sealing failure is the main defect of the oil-immersed transformer body, which accounts for about 15% of the total number of defects; if the sealing of the key parts of the transformer fails, it will directly lead to equipment failure. For example, the failure of the bushing seal allows moisture to enter, which directly leads to internal short circuit breakdown failure of the equipment, and even causes serious accidents such as equipment explosion and fire.

[0003] Research has found that the poor durability of sealing materials is one of the main reasons for oil leakage in oil-immersed transformers. At present, the sealing materials commonly used in oil-immersed transformers are mostly nitrile rubber (NBR) or acrylic rubber (ACM). Among them, the performance of nitrile rubber is significantly attenuated after long-term high-temperature oil resistance, and it is difficult to maintain good low-temperature performance for a long time. Although acrylic rubber has excellent resistance to thermal oxidation aging, oil resistance and heat resistance, its overall cross-linking degree is low, resulting in poor mechanical properties. To solve this problem, people began to use nitrile rubber and acrylic rubber with complementary advantages. However, since nitrile rubber is a diene rubber, and the main chain of the molecular chain of acrylic rubber is a saturated hydrocarbon, and the cross-linking mechanism and cross-linking system of the two are also different, the problem of asynchronous vulcanization of the nitrile rubber phase and the acrylic rubber phase will occur during the product vulcanization process, resulting in poor compatibility between nitrile rubber and acrylic rubber, and it is difficult to achieve the effect of complementary advantages. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a low temperature resistant polymer compatibilizer and a preparation method and application thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In the first aspect, the present invention provides a low temperature resistant polymer compatibilizer, which is obtained by esterification of carboxyl-containing acrylic rubber and terminal hydroxyl nitrile rubber (chemical reaction formula is as follows: Figure 1 shown).

[0007] The present invention combines the carboxyl-containing carboxylic acid type acrylate rubber with liquid hydroxyl-terminated nitrile rubber, forms a low temperature resistant polymer expander by esterification reaction of the carboxyl group in the carboxylic acid type acrylate rubber and the hydroxyl group in the liquid hydroxyl-terminated nitrile rubber, and the low temperature resistant polymer expander contains both acrylate rubber segments and nitrile rubber segments, which can not only effectively enhance the compatibility of the acrylate rubber phase and the nitrile rubber phase in the composite rubber elastomer, but also promote the dispersion of the two phases to significantly improve the mechanical properties of the composite rubber elastomer, but also enhance the flexibility of the composite rubber elastomer to greatly improve its low temperature performance. At the same time, due to the large molecular weight of the low temperature resistant polymer expander, it will not volatilize during the use of the composite rubber elastomer like other small molecule plasticizers, and then give the composite rubber elastomer excellent long-term low temperature resistance. In addition, a large amount of strong polar groups (such as acrylonitrile, carboxyl, etc.) contained by the low temperature resistant polymer expander can also give the composite rubber elastomer good oil-resistant extraction performance, suitable for use in various oil-containing environments (such as transformer oil).

[0008] As a preferred embodiment of the low temperature resistant polymer compatibilizer of the present invention, the mass ratio of the acrylic rubber to the hydroxy-terminated nitrile rubber is 1:(0.3-0.7). Optionally, the mass ratio of the acrylic rubber to the hydroxy-terminated nitrile rubber can be specifically 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, or any two of the range values. Studies have found that the mass ratio of acrylic rubber to hydroxy-terminated nitrile rubber will affect the composition of the residue in the low temperature resistant polymer compatibilizer. When the mass ratio of the two is within the above range, the long-term low temperature resistance and oil resistance of the composite rubber elastomer (NBR / ACM) can be better improved.

[0009] As a preferred embodiment of the low temperature resistant polymer compatibilizer of the present invention, the Mooney viscosity ML (1+4) of the acrylic rubber at 100°C is 23 to 38. Optionally, the Mooney viscosity of the acrylic rubber can be specifically a range of one or any two of 23, 25, 27, 29, 31, 33, 35, 38; the Mooney viscosity of the acrylic rubber can be determined using the standard GB / T 1232.1-2016. Studies have found that the Mooney viscosity of acrylic rubber can reflect its molecular weight and processing difficulty. The acrylic rubber within the above Mooney viscosity range can better enhance the compatibility of the low temperature resistant polymer compatibilizer with the composite rubber elastomer (NBR / ACM), and can maintain good production and processing performance.

[0010] As a preferred embodiment of the low temperature resistant polymer compatibilizer of the present invention, the mass content of carboxyl groups in the acrylic rubber is 3% to 5%. Optionally, the mass content of carboxyl groups in the acrylic rubber can be 3%, 3.5%, 4%, 4.5%, 5%, or any two of them. Studies have found that when the mass content of carboxyl groups is 3% to 5%, the acrylic rubber can be endowed with better mechanical properties and low temperature properties, thereby significantly improving the performance of the low temperature resistant polymer compatibilizer.

[0011] As a preferred embodiment of the low temperature resistant polymer compatibilizer of the present invention, the mass fraction of acrylonitrile in the hydroxyl-terminated nitrile rubber is 5% to 20%. Optionally, the mass fraction of acrylonitrile in the hydroxyl-terminated nitrile rubber can be 5%, 7%, 9%, 11%, 13%, 15%, 17%, 20% or any two of the range values; the mass fraction of acrylonitrile in the hydroxyl-terminated nitrile rubber can be determined by standard SH / T 1157. Studies have found that when the mass fraction of acrylonitrile is 5% to 20%, the hydroxyl-terminated nitrile rubber can have better mechanical properties and low temperature properties, thereby significantly improving the performance of the low temperature resistant polymer compatibilizer.

[0012] As a preferred embodiment of the low temperature resistant polymer compatibilizer of the present invention, the content of hydroxyl in the hydroxy-terminated nitrile rubber is 0.4-0.7mmol / g. Optionally, the content of hydroxyl in the hydroxy-terminated nitrile rubber can be specifically 0.4mmol / g, 0.45mmol / g, 0.5mmol / g, 0.55mmol / g, 0.6mmol / g, 0.65mmol / g, 0.7mmol / g or any two of the range values. Studies have found that the above-mentioned content of hydroxyl can better give the hydroxy-terminated nitrile rubber suitable reactivity, thereby enhancing the improvement of the performance of the low temperature resistant polymer compatibilizer on the composite rubber elastomer (NBR / ACM).

[0013] In a second aspect, the present invention provides a method for preparing the above-mentioned low-temperature resistant polymer compatibilizer, comprising the following steps:

[0014] First, the acrylic rubber solution, the hydroxy-terminated nitrile rubber solution and the catalyst are uniformly mixed, and then reacted (esterification reaction) at 60-70° C. in an inert gas atmosphere for 9-11 hours; then the pH of the reaction solution is adjusted to neutral, and a precipitant is added to precipitate a solid product, which is washed and dried to obtain a low-temperature resistant polymer compatibilizer.

[0015] Optionally, the reaction temperature of the esterification reaction in the above preparation method can be 60°C, 62°C, 64°C, 66°C, 68°C, or 70°C, and the reaction time can be 9h, 9.5h, 10h, 10.5h, or 11h.

[0016] Specifically, the above-mentioned acrylic rubber solution refers to a solution formed by dissolving carboxylic acid type acrylic rubber raw rubber in an organic solvent, and the terminal hydroxyl nitrile rubber solution refers to a solution formed by dissolving terminal hydroxyl nitrile rubber raw rubber in an organic solvent or terminal hydroxyl liquid nitrile rubber; the catalyst can be at least one of concentrated sulfuric acid and p-toluenesulfonic acid, preferably concentrated sulfuric acid; the precipitant is ethanol.

[0017] In a third aspect, the present invention provides the use of the above-mentioned low-temperature resistant polymer compatibilizer in a composite rubber elastomer, wherein the composite rubber elastomer comprises nitrile rubber and acrylic rubber.

[0018] Fourth aspect, the composite rubber elastomer of the present invention comprises nitrile rubber, acrylate rubber and compatibilizer, and the compatibilizer is the above-mentioned low temperature resistant polymer compatibilizer. Optionally, the mass ratio of nitrile rubber, acrylate rubber and compatibilizer in the composite rubber elastomer is (10-50): (50-90): (1-20); in parts by weight, the weight fraction of nitrile rubber in the composite rubber elastomer can be specifically 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, acrylate rubber can be specifically 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, and compatibilizer can be specifically 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts.

[0019] In a fifth aspect, the present invention provides a sealing component for an oil-immersed transformer, wherein the sealing component is made of the above-mentioned composite rubber elastomer.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention combines the carboxyl-containing carboxylic acid type acrylate rubber with liquid hydroxyl-terminated nitrile rubber, forms a low temperature resistant polymer expander by esterification reaction of the carboxyl group in the carboxylic acid type acrylate rubber and the hydroxyl group in the liquid hydroxyl-terminated nitrile rubber, and the low temperature resistant polymer expander contains both acrylate rubber segments and nitrile rubber segments, which can not only effectively enhance the compatibility of the acrylate rubber phase and the nitrile rubber phase in the composite rubber elastomer, but also promote the dispersion of the two phases to significantly improve the mechanical properties of the composite rubber elastomer, but also enhance the flexibility of the composite rubber elastomer to greatly improve its low temperature performance. At the same time, due to the large molecular weight of the low temperature resistant polymer expander, it will not volatilize during the use of the composite rubber elastomer like other small molecule plasticizers, and then give the composite rubber elastomer excellent long-term low temperature resistance. In addition, a large amount of strong polar groups (such as acrylonitrile, carboxyl, etc.) contained by the low temperature resistant polymer expander can also give the composite rubber elastomer good oil-resistant extraction performance, suitable for use in various oil-containing environments (such as transformer oil). BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the chemical reaction formula of the low temperature resistant polymer compatibilizer of the present invention. DETAILED DESCRIPTION

[0023] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0024] Unless otherwise specified, other materials, reagents, etc. used in the examples can be obtained from commercial sources.

[0025] Carboxylic acid type ACM-1 (raw rubber), manufacturer: Deya Resin Co., Ltd., brand name SA-353;

[0026] Carboxylic acid type ACM-2 (raw rubber), manufacturer: Japan Zeon Co., Ltd., brand name AR-12;

[0027] Hydroxyl-terminated NBR-1 (raw rubber), manufacturer Zibo Qilong Chemical Co., Ltd., brand HTBN-II;

[0028] Hydroxyl-terminated NBR-2 (raw rubber), manufacturer: Zibo Qilong Chemical Co., Ltd., brand: HTBN-IV.

[0029] 1) Low temperature resistant polymer compatibilizer

[0030] Table 1 Weight parts of each raw material component in low temperature resistant polymer compatibilizer 1 to 5

[0031]

[0032] The preparation method of the above-mentioned low temperature resistant polymer compatibilizer comprises the following steps:

[0033] S1, the carboxylic acid type ACM solution (concentration 70g / L, solvent is toluene) and concentrated sulfuric acid are mixed evenly, and then the terminal hydroxyl NBR solution (concentration 60g / L, solvent is toluene) is added dropwise to the mixed solution at room temperature; then under the protection of nitrogen atmosphere, the temperature of the reaction system is raised to 70°C, and the reaction is stirred for 10 hours to obtain a mixed solution;

[0034] S2. The mixed solution in S1 is adjusted to neutral (pH=7), and then a precipitant (ethanol) is added to stir and precipitate a solid product. The solid product is washed and dried to obtain a low-temperature resistant polymer compatibilizer.

[0035] 2) ACM masterbatch

[0036] ACM masterbatch is composed of ACM raw rubber (SA-201 produced by Deya Resin Co., Ltd.), reinforcing filler (carbon black N330), scorch retarder (N-cyclohexylthiophthalimide), antioxidant (antioxidant 445) and vulcanizing agent (composed of sulfur, potassium stearate and sodium stearate in a mass ratio of 0.3:0.3:2.5) in a mass ratio of 100:55:1:0.3:2:3.1.

[0037] The preparation method of the above-mentioned ACM masterbatch comprises the following steps:

[0038] Add ACM raw rubber into an open mixing mill for thin passing. After the rubber is thinly passed through the roller, reinforcing fillers, processing aids, antioxidants, anti-scorch agents and vulcanizers are added to the ACM raw rubber and mixed for 0.5 to 1 hour. After mixing evenly, sheets are produced to obtain ACM masterbatch.

[0039] 3) NBR masterbatch

[0040] NBR masterbatch is composed of NBR raw rubber (JSR N230S from Japan JSR Company), activator (zinc oxide and stearic acid in a mass ratio of 5:0.5), reinforcing filler (carbon black N774), processing aid (SRP66), antioxidant (antioxidant 4010NA and antioxidant ZMBI in a mass ratio of 3:3), and vulcanizing agent (diisopropylbenzene peroxide) in a mass ratio of 100:5.5:55:1:6:2.5.

[0041] The preparation method of the above-mentioned NBR masterbatch comprises the following steps:

[0042] Add NBR raw rubber into an open mixing mill for thin passing. After the rubber is thinly passed through a roller, reinforcing fillers, activators, processing aids, antioxidants and vulcanizers are added to the NBR raw rubber and mixed for 0.5 to 1 hour. After mixing evenly, sheets are produced to obtain NBR masterbatch.

[0043] Examples 1 to 8 and Comparative Examples 1 to 3

[0044] Table 2 Weight fractions of each component in the composite rubber elastomer in each embodiment and comparative example

[0045]

[0046] Among them, the plasticizer TP-95 in Table 1 is dibutyl diglycerol adipate, and the plasticizer DOS is dioctyl sebacate.

[0047] The preparation method of the composite rubber elastomer comprises the following steps:

[0048] S1. Add ACM masterbatch into an open mixer and pass it through a thin roller. After the rubber is thinly passed through the roller, cut the NBR masterbatch into pieces and slowly add it into the ACM masterbatch for mixing for 0.5 to 1 hour. After mixing evenly, flake out to obtain NBR / ACM blended rubber.

[0049] S2. Add the NBR / ACM blended rubber in S1 into an open mixing mill for thin passing, then add a low temperature resistant polymer compatibilizer or plasticizer into the NBR / ACM blended rubber and mix for 0.5 to 1 hour. After mixing evenly, form a sheet to obtain a composite rubber elastomer.

[0050] Performance Testing

[0051] The composite rubber elastomers prepared in Examples 1 to 8 and Comparative Examples 1 to 3 were left for more than 16 hours, and then vulcanized using a two-stage vulcanization process, wherein the temperature of the first stage vulcanization was 170°C, the pressure was 18 MPa, and the time was 15 min, and the temperature of the second stage vulcanization was 150°C, and the time was 3 hours; then the composite rubber elastomer, ACM masterbatch and NBR masterbatch after vulcanization were respectively tested as follows, and the test results are shown in Table 3.

[0052] 1) The tensile strength and elongation at break are tested according to GB / T 528-2009 standard, and the test specimen is type 1 specimen;

[0053] 2) Low temperature shrinkage temperature (TR10) is tested according to standard GB / T 7758-2020;

[0054] 3) Resistance to 25# transformer oil (Great Wall Lubricant) is tested using standard GB / T 1690-2010.

[0055] Table 3 Properties of composite rubber elastomers, ACM masterbatch and NBR masterbatch in various embodiments and comparative examples

[0056]

[0057] According to the data in Table 3, the tensile strength of the composite rubber elastomer in Examples 1 to 8 is ≥16.8MPa, the elongation at break is ≥438%, the low-temperature retraction temperature (TR10) is -18.2~-25.2°C, the TR10 (120°C×72h) after the 25# transformer oil test is -18.2~-24.9°C, and the TR10 (120°C×168h) is -18.5~-24.3°C, indicating that the low-temperature resistant polymer compatibilizer of the present invention can significantly improve the mechanical properties, low-temperature properties and oil resistance of the rubber composite elastomer.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A low temperature resistant polymer compatibilizer, characterized in that: It is obtained by esterification reaction of carboxyl-containing acrylic rubber and terminal hydroxyl nitrile rubber.

2. The low temperature resistant polymer compatibilizer according to claim 1, characterized in that: The mass ratio of the acrylic rubber to the hydroxy-terminated nitrile rubber is 1:(0.3-0.7).

3. The low temperature resistant polymer compatibilizer according to claim 1, characterized in that: The Mooney viscosity ML (1+4) of the acrylic rubber at 100° C. is 23-38.

4. The low temperature resistant polymer compatibilizer according to claim 1, characterized in that: The mass content of carboxyl groups in the acrylic rubber is 3% to 5%.

5. The low temperature resistant polymer compatibilizer according to claim 1, characterized in that: The mass fraction of acrylonitrile in the hydroxy-terminated nitrile rubber is 5% to 20%.

6. The low temperature resistant polymer compatibilizer according to claim 1, characterized in that: The content of hydroxyl groups in the hydroxy-terminated nitrile rubber is 0.4-0.7 mmol / g.

7. The method for preparing the low temperature resistant polymer compatibilizer according to any one of claims 1 to 6, characterized in that: The following steps are involved: First, the acrylic rubber solution, the hydroxy-terminated nitrile rubber solution and the catalyst are uniformly mixed, and then reacted at 60-70°C in an inert gas atmosphere for 9-11 hours; then the pH of the reaction solution is adjusted to neutral, and a precipitant is added to precipitate a solid product, which is washed and dried to obtain a low-temperature resistant polymer compatibilizer.

8. Use of the low temperature resistant polymer compatibilizer according to any one of claims 1 to 6 in a composite rubber elastomer, wherein the composite rubber elastomer comprises nitrile rubber and acrylic rubber.

9. A composite rubber elastic body, characterized in that: The invention comprises nitrile rubber, acrylic rubber and a compatibilizer, wherein the compatibilizer is the low temperature resistant polymer compatibilizer according to any one of claims 1 to 6.

10. A sealing component for an oil-immersed transformer, characterized in that: Made from the composite rubber elastomer according to claim 9.

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