Low-temperature-resistant ethylene-acrylate copolymer as well as preparation method and application thereof

Abstract

The invention relates to the field of rubber materials, and discloses a low-temperature-resistant ethylene-acrylate copolymer and a preparation method and application thereof.The copolymer comprises a structural unit A from acrylate, a structural unit B from ethylene and a structural unit C from a third monomer, the third monomer is selected from at least one of glycidyl methacrylate, methoxyethyl acrylate and allyl glycidyl ether; based on the total amount of the copolymer, the molar content of the structural unit A is 30-60%, the molar content of the structural unit B is 30-45%, and the molar content of the structural unit C is 10-30%. By controlling the molar content of the ethylene and the molar content of the third monomer, the prepared ethylene-acrylate copolymer has more excellent low-temperature resistance; and the preparation process is simple, easy to operate and low in requirements on operators and equipment.

Description

Technical Field

[0001] The invention relates to the technical field of rubber materials, and in particular to a low-temperature resistant ethylene-acrylate copolymer and a preparation method and application thereof. Background Art

[0002] Acrylic rubber can be divided into two categories according to its main monomer: acrylic rubber (ACM for short) and ethylene-acrylate rubber (AEM for short).

[0003] Foreign countries have been studying ACM relatively early, and the technology is relatively mature. As early as 1912, Otto discovered that sulfur could cross-link polyacrylates, but the resulting elastomer was of no use value. In the 1960s, Goodrich Company in the United States had successfully developed self-cross-linking ACM rubber. In 1963, American Cyanamid Company produced active chlorine-type ACM rubber under the trade name Cyanacry. Because active chlorine-type ACM will dechlorinate to produce HCl under high temperature, it will cause environmental pollution and mold corrosion, and metals have a strong affinity with chlorine atoms, and serious sticking to the rollers often occurs, which brings great difficulties to the processing of rubber. Japan's Tohpe Company, Zeon Company and Goodrich Company in the United States introduced monomers with epoxy functional groups and successfully developed epoxy ACM. Although epoxy ACM does not contain chlorine and does not corrode, its epoxy functional group is easy to open during the synthesis process to form a network structure molecular chain, resulting in an unstable polymerization system and low molecular weight. In 1983, JSR (Japan) Company used ethylidene norbornene (ENB) as a vulcanization monomer and achieved the industrialization of unsaturated ACM.

[0004] The most famous AEM is Vamac, which was launched by DuPont in the United States in 1975. Vamac is the trademark name registered by DuPont for ethylene-acrylate elastomer. It mainly prepares ethylene-acrylate elastomer by solution method. The ethylene-acrylate rubber prepared by this method has excellent low-temperature resistance, but there are also problems such as harsh production conditions and complex equipment. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of harsh production conditions and complex equipment in the preparation of low-temperature resistant rubber in the prior art, and to provide a low-temperature resistant ethylene-acrylate copolymer and a preparation method and application thereof. The method is simple and easy to operate and has low requirements on equipment.

[0006] In order to achieve the above object, the first aspect of the present invention provides an ethylene-acrylate copolymer, wherein the copolymer comprises a structural unit A derived from acrylate, a structural unit B derived from ethylene, and a structural unit C derived from a third monomer, wherein the third monomer is selected from at least one of glycidyl methacrylate, methoxyethyl acrylate, and allyl glycidyl ether;

[0007] Based on the total amount of the copolymer, the molar content of the structural unit A is 30-60%, the molar content of the structural unit B is 30-45%, and the molar content of the structural unit C is 10-30%.

[0008] The second aspect of the present invention provides a method for preparing an ethylene-acrylate copolymer, wherein an acrylate monomer, an ethylene monomer and a third monomer are polymerized in the presence of a surfactant and an initiator, wherein the pressure of the ethylene is 10-15 MPa.

[0009] The third aspect of the present invention provides a copolymer, wherein the copolymer is prepared by the preparation method provided by the second aspect of the present invention.

[0010] A fourth aspect of the present invention provides an application of an ethylene-acrylate copolymer as a low-temperature resistant rubber or a toughening agent.

[0011] Through the above technical scheme, a low-temperature resistant third monomer is introduced into the ethylene-acrylate copolymer, so that the obtained copolymer has low-temperature resistance. Compared with the high-temperature and high-pressure preparation conditions of 200MPa and 200-300°C required by DuPont Company of the United States, the pressure of the preparation method of the present invention is only 10-15MPa, and high temperature is not required. Therefore, there is no need for complicated high-temperature and ultra-high-pressure equipment, the equipment is simple, and the production conditions are simple and easy to implement.

[0012] The glass transition temperature of traditional low-temperature resistant rubber is about -20°C, while the present invention controls the molar content of ethylene and the third monomer so that the prepared ethylene-acrylate copolymer has better low-temperature resistance, a simple preparation process, easy operation, and low requirements on operators and equipment. DETAILED DESCRIPTION

[0013] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0014] The first aspect of the present invention provides an ethylene-acrylate copolymer, wherein the copolymer comprises a structural unit A derived from acrylate, a structural unit B derived from ethylene, and a structural unit C derived from a third monomer, wherein the third monomer is selected from at least one of glycidyl methacrylate, methoxyethyl acrylate, and allyl glycidyl ether;

[0015] Based on the total amount of the copolymer, the molar content of the structural unit A is 30-60%, the molar content of the structural unit B is 30-45%, and the molar content of the structural unit C is 10-30%.

[0016] The content of ethylene and the third monomer affects the low temperature resistance of the obtained product. Calculated by mole, the molar content of the structural unit A can be any value within the numerical range of any two of 30%, 35%, 40%, 45%, 50%, 55%, and 60%, the molar content of the structural unit B can be any value within the numerical range of any two of 30%, 35%, 40%, and 45%, and the molar content of the structural unit C can be any value within the numerical range of any two of 10%, 15%, 20%, 25%, and 30%. The acrylate monomer is methyl acrylate and / or butyl acrylate.

[0017] In some embodiments of the present invention, preferably, the glass transition temperature of the copolymer is not higher than -40°C, preferably not higher than -50°C. The glass transition temperature of the ethylene-acrylate copolymer may be any value within any numerical range of not higher than -40°C, -45°C, -50°C, -55°C, -60°C, and -70°C.

[0018] The second aspect of the present invention provides a method for preparing a copolymer, wherein, in the presence of a surfactant and an initiator, an acrylate monomer, an ethylene monomer and a third monomer are subjected to polymerization reaction, wherein the pressure of the ethylene is 10-15MPa. The pressure of ethylene has a greater influence on the performance of the copolymer obtained, and the ethylene pressure affects the ethylene insertion rate (i.e., the content of ethylene in the polymer), thereby affecting the low temperature resistance and tensile strength, especially the low temperature resistance, and the ethylene pressure can be any value within the numerical range of any two of 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, and 15MPa. The surfactant is sodium dodecyl sulfate and / or alkoxy polyethylene oxide, the initiator is potassium persulfate and / or sodium persulfate, and the polymerization time is 1-6h, specifically any value within the numerical range of any two of 1h, 3h, and 6h.

[0019] In some embodiments of the present invention, preferably, the molar amount of the initiator is 1 / 100-1 / 2000 of the total molar amount of the acrylate monomer and the third monomer. The amount of the initiator affects the molecular weight and glass transition temperature of the prepared product, and the molar amount of the initiator can be any value within the numerical range consisting of any two numbers of 1 / 100, 1 / 300, 1 / 500, 1 / 700, 1 / 1000, 1 / 1500, 1 / 1800, and 1 / 2000 of the total molar amount of the acrylate monomer and the third monomer. The molar amount of the initiator is preferably 1 / 500-1 / 700 of the total molar amount of the acrylate monomer and the third monomer, and can be any value within the numerical range consisting of any two numbers of 1 / 500, 1 / 600, and 1 / 700, and is particularly preferably 1 / 500.

[0020] In some embodiments of the present invention, preferably, the preparation method further comprises: after the polymerization reaction is completed, adding a demulsifier to demulsify; wherein the demulsifier is at least one of a carboxylate solution, a sulfonate solution and a double salt solution. The demulsifier used is non-toxic or low-toxic, does not contain methanol or phenol, is environmentally friendly, and has high demulsification efficiency, large product output, high yield, and less waste liquid generated.

[0021] In some embodiments of the present invention, preferably, the carboxylate solution is a sodium acetate solution and / or a potassium acetate solution.

[0022] In some embodiments of the present invention, preferably, the sulfonate solution is a sodium sulfate solution and / or a potassium sulfate solution.

[0023] In some embodiments of the present invention, preferably, the double salt solution is potassium aluminum sulfate solution.

[0024] In some embodiments of the present invention, preferably, based on the total amount of the demulsifier, the mass percentage concentration of the demulsifier is 3-6%. The mass percentage concentration of the demulsifier refers to the mass proportion of the solute contained in the demulsifier, and the mass percentage concentration of the demulsifier can be any value within the numerical range of any two of 3%, 4%, 5%, and 6%.

[0025] In some embodiments of the present invention, preferably, the demulsifier is potassium aluminum sulfate solution, and the concentration of the potassium aluminum sulfate solution is preferably 5%.

[0026] In some embodiments of the present invention, preferably, the polymerization reaction is carried out at a temperature of 30-60° C., preferably 30-45° C. The polymerization reaction temperature is low, the energy consumption is low, the reaction temperature is mild and easy to control, and the reaction temperature can be any value within the numerical range of any two of 30° C., 40° C., 50° C., and 60° C., or any value within the numerical range of any two of 30° C., 35° C., 40° C., and 45° C.

[0027] The third aspect of the present invention provides a copolymer prepared by the preparation method of the second aspect of the present invention.

[0028] A fourth aspect of the present invention provides an application of a copolymer as a low-temperature resistant rubber or a toughening agent.

[0029] The ethylene-acrylate copolymer of the present invention has excellent low-temperature resistance and is suitable for use in an extremely low-temperature environment.

[0030] According to a particularly preferred embodiment of the present invention, the copolymer comprises a structural unit A derived from an acrylic acid ester, a structural unit B derived from ethylene, and a structural unit C derived from a third monomer, wherein the third monomer is selected from at least one of glycidyl methacrylate, methoxyethyl acrylate, and allyl glycidyl ether;

[0031] Based on the total amount of the copolymer, the molar content of the structural unit A is 30-45%, the molar content of the structural unit B is 38-40%, and the molar content of the structural unit C is 20-30%.

[0032] The present invention will be described in detail below through examples. In the following examples, the glass transition temperature is obtained by differential scanning calorimetry, and the tensile strength is obtained by universal testing machine.

[0033] Methyl acrylate is a commercial product of Aladdin with CAS number 96-33-3;

[0034] Butyl acrylate is a commercial product of Aladdin Company with brand number 138-1491-8216;

[0035] Glycidyl methacrylate is a commercial product of Aladdin Company with the brand number 106-91-2;

[0036] Methoxyethyl acrylate is a commercial product of Aladdin Company with the brand number 3121-61-7;

[0037] Allyl glycidyl ether is a commercial product sold by Aladdin Company with the brand number 106-92-3;

[0038] Ethylene is a commercial product from Messer Gas AG.

[0039] Example 1

[0040] Weigh 1.08 mol of butyl acrylate, 0.12 mol of methyl acrylate, and 0.12 mol of glycidyl methacrylate and put them into a 2 L reactor;

[0041] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0042] Calculate by mole, weigh 1 / 100 of the total amount of the acrylate monomer and the third monomer, potassium persulfate, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0043] The surfactant aqueous solution and the initiator aqueous solution are put into the reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 10MPa, the polymerization temperature is 30°C, the reaction is carried out for 3h, and 800mL of 5% sodium acetate solution by mass is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0044] Example 2

[0045] Weigh 1.08 mol of butyl acrylate, 0.12 mol of methyl acrylate, and 0.24 mol of glycidyl methacrylate and put them into a 2 L reactor;

[0046] Weighing a suitable amount of alkoxy polyethylene oxide, and adding it to deionized water to obtain a surfactant aqueous solution, wherein the concentration of the surfactant aqueous solution is 0.5 mol / L;

[0047] Calculate by mole, weigh potassium persulfate in an amount of 1 / 2000 of the total amount of the acrylate monomer and the third monomer, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0048] The surfactant aqueous solution and the initiator aqueous solution are put into the reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 15MPa, the polymerization temperature is 60°C, the reaction is carried out for 3h, and 800mL of potassium sulfate solution with a mass percentage concentration of 3% is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0049] Example 3

[0050] Weigh 1.2 mol of butyl acrylate and 0.36 mol of glycidyl methacrylate and put them into a 2 L reactor;

[0051] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0052] Calculate by mole, weigh 1 / 500 of the total amount of the acrylate monomer and the third monomer, potassium persulfate, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0053] The surfactant aqueous solution and the initiator aqueous solution are put into the reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 13 MPa, the polymerization temperature is 45°C, the reaction is carried out for 3 hours, and 800 mL of potassium aluminum sulfate solution with a mass percentage concentration of 6% is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0054] Comparative Example 1

[0055] Weigh 1.2 mol of butyl acrylate and 0.36 mol of glycidyl methacrylate and put them into a 2 L reactor;

[0056] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0057] Calculate by mole, weigh 1 / 500 of the total amount of the acrylate monomer and the third monomer, potassium persulfate, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0058] The surfactant aqueous solution and the initiator aqueous solution were put into the reactor, the air in the reactor was replaced by ethylene three times, the ethylene pressure was adjusted to 1 MPa, the polymerization temperature was 45°C, the reaction was carried out for 3 hours, and 800 mL of potassium aluminum sulfate solution with a mass percentage concentration of 6% was added for demulsification to obtain a comparative sample.

[0059] Example 4

[0060] Weigh 0.24 mol of methyl acrylate, 0.96 mol of butyl acrylate, and 0.12 mol of allyl glycidyl ether and put them into a 2 L reactor;

[0061] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0062] Calculate by mole, weigh 1 / 500 of the total amount of the acrylic acid ester monomer and the third monomer, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0063] The surfactant aqueous solution and the initiator aqueous solution are put into the reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 15MPa, the polymerization temperature is 60°C, the reaction is carried out for 3h, and 800mL of 5% potassium aluminum sulfate solution is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0064] Example 5

[0065] Weigh 0.36 mol of methyl acrylate, 0.84 mol of butyl acrylate, and 0.24 mol of allyl glycidyl ether and put them into a 2 L reactor;

[0066] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0067] Calculate by mole, weigh 1 / 500 of the total amount of the acrylic acid ester monomer and the third monomer, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0068] The surfactant aqueous solution and the initiator aqueous solution are put into the reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 15MPa, the polymerization temperature is 60°C, the reaction is carried out for 3h, and 800mL of 5% potassium aluminum sulfate solution is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0069] Comparative Example 2

[0070] Weigh 0.36 mol of methyl acrylate and 0.84 mol of butyl acrylate and put them into a 2 L reactor;

[0071] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0072] Calculate by mole, weigh 1 / 500 of the total amount of the acrylic acid ester monomer and the third monomer, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0073] The surfactant aqueous solution and the initiator aqueous solution were put into the reactor, the air in the reactor was replaced by ethylene three times, the ethylene pressure was adjusted to 15 MPa, the polymerization temperature was 60°C, the reaction was carried out for 3 hours, and 800 mL of potassium aluminum sulfate solution with a mass percentage concentration of 5% was added for demulsification to obtain a comparative sample.

[0074] Example 6

[0075] Weigh 0.48 mol of methyl acrylate, 0.72 mol of butyl acrylate, and 0.36 mol of allyl glycidyl ether and put them into a 2 L reactor;

[0076] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0077] Calculate by mole, weigh 1 / 500 of the total amount of the acrylate monomer and the third monomer, potassium persulfate, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0078] The surfactant aqueous solution and the initiator aqueous solution are put into a reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 10 MPa, the polymerization temperature is 60°C, the reaction is carried out for 3 hours, and 800 mL of 5% potassium aluminum sulfate solution is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0079] Example 7

[0080] Weigh 0.72 mol of methyl acrylate, 0.48 mol of butyl acrylate, and 0.24 mol of methoxyethyl acrylate and put them into a 2 L reactor;

[0081] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0082] Calculate by mole, weigh 1 / 500 of the total amount of the acrylate monomer and the third monomer, potassium persulfate, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0083] The surfactant aqueous solution and the initiator aqueous solution are put into the reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 15MPa, the polymerization temperature is 60°C, the reaction is carried out for 3h, and 800mL of 5% potassium aluminum sulfate solution is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0084] Example 8

[0085] Weigh 0.36 mol of methyl acrylate, 0.84 mol of butyl acrylate, and 0.36 mol of methoxyethyl acrylate and put them into a 2 L reactor;

[0086] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0087] Calculate by mole, weigh 1 / 500 of the total amount of the acrylate monomer and the third monomer, potassium persulfate, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0088] The surfactant aqueous solution and the initiator aqueous solution are put into the reactor, the air in the reactor is replaced by ethylene three times, the ethylene pressure is adjusted to 15MPa, the polymerization temperature is 60°C, the reaction is carried out for 3h, and 800mL of 5% potassium aluminum sulfate solution is added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0089] Comparative Example 9

[0090] Weigh 0.48 mol of methyl acrylate, 0.72 mol of butyl acrylate, and 0.36 mol of allyl glycidyl ether and put them into a 2 L reactor;

[0091] Weigh an appropriate amount of sodium dodecyl sulfate and add it to deionized water to obtain an aqueous surfactant solution, wherein the concentration of the aqueous surfactant solution is 0.5 mol / L;

[0092] Calculate by mole, weigh 1 / 500 of the total amount of the acrylate monomer and the third monomer, potassium persulfate, and dissolve it in 50 mL of deionized water to obtain an initiator aqueous solution;

[0093] The surfactant aqueous solution and the initiator aqueous solution were put into the reactor, and the air in the reactor was replaced by ethylene three times. The ethylene pressure was adjusted to 10 MPa, the polymerization temperature was 60°C, and the reaction was carried out for 3 hours. 0.3 L of 20 mmol / L methanol solution of hydroquinone was added for demulsification to obtain a low-temperature resistant ethylene-acrylate copolymer.

[0094] The test results of the above embodiments and comparative examples are shown in Table 1.

[0095] Table 1 Test results

[0096]

[0097] It can be seen from Table 1 that the yield of the copolymer prepared by the preparation method provided by the present invention is as high as over 90%, and the amount of waste liquid is extremely low, which is mainly affected by the demulsifier. The glass transition temperature of the obtained copolymer is not higher than -40°C, and it has good tensile strength.

[0098] By comparing Example 3 with Comparative Example 1, it can be seen that the ethylene pressure selected by the present invention can make the copolymer have a lower glass transition temperature. By comparing Example 5 with Comparative Example 2, it can be seen that the copolymer prepared by the present invention, wherein the content of the third monomer is higher, the glass transition temperature of the copolymer is also lower. By comparing Example 6 with Example 9, the two are prepared with the same raw materials, and the only difference is that the demulsifier selected after the reaction is completed is different. It can be seen that the yield and the amount of waste liquid of the two are very different, which shows that the type of demulsifier selected has a huge impact on the yield and the amount of waste liquid of the copolymer. The demulsifier selected by the present invention can make the yield of the copolymer higher and the amount of waste liquid generated less at the same time.

[0099] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A copolymer, characterized in that The copolymer comprises a structural unit A derived from acrylic acid ester, a structural unit B derived from ethylene, and a structural unit C derived from a third monomer, wherein the third monomer is selected from at least one of glycidyl methacrylate, methoxyethyl acrylate, and allyl glycidyl ether; Based on the total amount of the copolymer, the molar content of the structural unit A is 30-60%, the molar content of the structural unit B is 30-45%, and the molar content of the structural unit C is 10-30%.

2. The copolymer according to claim 1, characterized in that The glass transition temperature of the copolymer is not higher than -40°C, preferably not higher than -50°C.

3. A method for preparing a copolymer, characterized in that: In the presence of a surfactant and an initiator, an acrylate monomer, an ethylene monomer and a third monomer are polymerized, wherein the pressure of the ethylene is 10-15 MPa.

4. The preparation method according to claim 3, characterized in that: The molar amount of the initiator is 1 / 100-1 / 2000 of the total molar amount of the acrylate monomer and the third monomer.

5. The preparation method according to claim 3 or 4, characterized in that: The preparation method further comprises: after the polymerization reaction is completed, adding a demulsifier to perform demulsification; wherein the demulsifier is at least one of a carboxylate solution, a sulfonate solution and a double salt solution.

6. The preparation method according to claim 5, characterized in that: The carboxylate solution is a sodium acetate solution and / or a potassium acetate solution; Preferably, the sulfonate solution is a sodium sulfate solution and / or a potassium sulfate solution; Preferably, the double salt solution is potassium aluminum sulfate solution.

7. The preparation method according to claim 5 or 6, characterized in that: Based on the total amount of the demulsifier, the mass percentage concentration of the demulsifier is 3-6%.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The demulsifier is potassium aluminum sulfate solution.

9. A copolymer obtained by the preparation method according to any one of claims 3 to 8.

10. Use of the copolymer according to any one of claims 1, 2 and 9 as a low-temperature resistant rubber or toughening agent.

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