A carbomer and a method for preparing the same

Abstract

The present application provides a kind of preparation method of carbomer, comprising the following steps: (1) acrylic monomer is added to mixed solvent, inert gas is introduced, then photo initiator, dispersing agent and polyene crosslinking agent are added, after stirring under ultraviolet lamp for a period of time, dropwise addition of thermal initiator, reaction for a period of time, add multi mercapto crosslinking agent, control reaction temperature and continue to react;(2) filter and wash the reaction product, dry to obtain carbomer.The preparation method of the present application carbomer is simple, fast and efficient, without heating, rely on ultraviolet lamp and reaction process to provide reaction temperature, while introducing mercapto-alkene reaction, reaction efficiency is high, the molecular weight of polymer is improved.The reaction process is not only safe and pollution-free, but also the product has high molecular weight, low residual single content, low product odor, enhanced ultraviolet resistance, high viscosity and good transparency.

Description

Technical Field

[0001] This invention relates to a carbomer and its preparation method, belonging to the field of acrylic resin materials. Background Technology

[0002] Carbomer is a homopolymer or copolymer of acrylic acid. It has excellent suspending, thickening, stabilizing and emulsifying abilities and is widely used in cosmetics and pharmaceuticals.

[0003] Carbomer preparation methods mainly include emulsion polymerization and solution polymerization. Emulsion polymerization uses water or other solvents as a medium to generate individual latex particles through micellar nucleation or oligomer nucleation mechanisms. These particles then undergo free radical addition polymerization or ionic addition polymerization to produce high molecular weight polymers. For example, Chinese patent CN103755861A discloses a carbomer and its preparation method, using water as a solvent to prepare carbomer via emulsion polymerization. This method suffers from drawbacks such as low carbomer yield, high energy consumption, and low viscosity. Solution polymerization refers to a polymerization reaction in which monomers and initiators are dissolved in a suitable solvent. The resulting polymer is insoluble in the chosen solvent and precipitates out during the reaction; this is called heterogeneous solution polymerization, also known as precipitation polymerization. Solution polymerization is characterized by easy reaction control and a narrow molecular weight range of the products. For example, Chinese patent CN103483491A discloses a carbomer and its preparation method, which uses acrylic acid as a monomer to prepare a carbomer through a mixed solution. However, this method has drawbacks such as complex process and low product viscosity. Currently, the polymer products prepared by existing methods have low molecular weight and low viscosity. The ultraviolet-sensitive segments and small molecule monomers cannot react completely, resulting in poor UV resistance of the obtained products, which greatly limits the application fields of the products. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a carbomer and its preparation method. Using acrylic acid as a raw material, and employing a combination of photoinitiators and thermal initiators, carbomer is prepared through a free radical polymerization reaction under ultraviolet light. No heating is required during the reaction; the reaction temperature is rapidly controlled by directly adjusting the power of the ultraviolet lamp, and precise temperature control is achieved by using a drop-heating initiator. Simultaneously, a thiol-ene click reaction is introduced, resulting in high reaction efficiency, increased product crosslinking degree, and facilitating the preparation of high molecular weight products. This leads to a significant increase in product viscosity, and the thiol-ene click reaction consumes excess double bonds, greatly reducing the number of ultraviolet-sensitive segments and small monomers after the reaction. The carbomer obtained by this invention exhibits high viscosity, excellent transparency, and good ultraviolet resistance.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention provides a method for preparing carbomer, comprising the following steps:

[0007] (1) Add acrylic monomer to mixed solvent, pass in inert gas, then add photoinitiator, dispersant and polyene crosslinking agent, stir and react under ultraviolet light for a period of time, then add heating initiator dropwise, react for a period of time, add polythiol crosslinking agent, and control the reaction temperature to continue the reaction.

[0008] (2) The reaction product was filtered and washed, and then dried to obtain carbomer.

[0009] Preferably, the water content in the acrylic monomer is less than 0.01%.

[0010] Preferably, the inert gas is selected from argon, nitrogen, and helium.

[0011] Preferably, in step (1), the mixed solvent is two or more of ethyl acetate, cyclohexane, n-hexane, and chloroform. More preferably, in step (1), the mixed solvent is ethyl acetate and cyclohexane, and the volume ratio of the solvents is 1.25-1.5:1.

[0012] Preferably, in step (1), the concentration of acrylic monomer in the mixed solvent is 0.1-0.5 g / ml; preferably, the concentration of acrylic acid is 0.1-0.25 g / ml.

[0013] Preferably, in step (1), the photoinitiator is one or more of benzophenone, benzoin isopropyl ether, diphenyl ethyl ketone, benzoin dimethyl ether, and benzoin ethyl ether; the thermal initiator is one or more of benzoyl peroxide, azobisisobutyronitrile, potassium persulfate, benzoyl peroxide, and azobisisoheptanenitrile. Preferably, the photoinitiator is benzoin dimethyl ether, the thermal initiator is benzoyl peroxide, and the amount of photoinitiator added is 0.2%-0.5% of the mass of acrylic acid, and the amount of thermal initiator added is 0.2%-0.5% of the mass of acrylic acid.

[0014] Preferably, in step (1), the dispersant is one or more of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, sodium dodecyl sulfate, alkylphenol polyoxyethylene ether, and Hypermer B246; preferably, the dispersant is Hypermer B246, and the amount of dispersant added is 0.2%-0.6% of the mass of acrylic monomer.

[0015] Preferably, in step (1), the polyene crosslinking agent is selected from one or more of pentaerythritol triallyl ether, allyl sucrose ether, diallyl phthalate, and methylenebisacrylamide. Preferably, the polyene crosslinking agent is pentaerythritol triallyl ether, and the amount added is 0.01%-1% of the mass of acrylic acid. The polythiol crosslinking agent is selected from one or more of ethylenedithiol, 1,3-propanedithiol, and pentaerythritol tetra-3-mercaptopropionate. Preferably, the polythiol crosslinking agent is pentaerythritol tetra-3-mercaptopropionate, and the amount added is 0.01%-1% of the mass of acrylic acid.

[0016] Preferably, in step (1), the wavelength of the ultraviolet lamp is 320-395nm and the power is 0.01W-50W. More preferably, the power of the ultraviolet lamp is 0.5W-20W and the wavelength is 340-375nm.

[0017] Preferably, in step (1), the reaction temperature is 70-72℃, the stirring speed is 250-750 rpm / min, and the reaction time under ultraviolet light is 1h-4h.

[0018] Preferably, in step (1), the reaction time after adding the heating initiator is 1-3 hours, and the reaction time after adding the multi-thiol crosslinking agent is 0.5-2 hours.

[0019] Preferably, in step (2), the washing solvent is one or both of ethyl acetate and cyclohexane, and the washing is performed 3-4 times.

[0020] Preferably, in step (2), the drying process is one of vacuum drying, atmospheric pressure drying, and radiation drying, and the drying temperature is 80-110℃, with a drying time of 7-10h. Preferably, the drying process is vacuum drying, with a drying temperature of 90-100℃ and a drying time of 8-9h.

[0021] The principle of this invention is as follows: a free radical polymerization reaction and a mercapto-olefin reaction are initiated by an ultraviolet lamp. The polymerization process is an exothermic reaction and does not require heating. This provides the reaction temperature for the acrylic acid polymerization. A heating initiator is dropped in, and the temperature of the system is precisely controlled by adjusting the power of the ultraviolet lamp. The reaction is simple, fast, and efficient, and finally a carbomer material with high viscosity, good transparency, and good UV resistance is obtained.

[0022] Polyolefin crosslinking agents can participate in the polymerization of acrylic acid in the initial reaction stage, thereby achieving the initial crosslinking of acrylic acid. After the initial crosslinking, the polyolefin crosslinking agent has remaining double bonds. At this time, adding polythiol crosslinking agents can further achieve the crosslinking of acrylic acid, thereby increasing the molecular weight of carbomer. At the same time, it greatly reduces the UV-sensitive chain segments and small molecule monomers, giving the resulting product excellent UV resistance.

[0023] The beneficial effects of this invention are as follows:

[0024] (1) This invention employs ultraviolet light-initiated polymerization. Compared to traditional thermal initiation processes, the reaction temperature can be rapidly controlled by directly adjusting the power of the ultraviolet lamp, while simultaneously heating the initiator by dropping it, achieving precise temperature control without any lag in temperature control. This results in more complete reactions in all parts of the reactor, leading to a uniform molecular structure, low residual monomer content, and minimal odor in the product. Furthermore, the introduction of a mercapto-olefin click reaction increases reaction efficiency, which is beneficial for preparing high molecular weight products. This significantly increases the product viscosity, and the number of ultraviolet-sensitive segments and small monomers is greatly reduced after the reaction, resulting in a product with excellent ultraviolet resistance.

[0025] (2) The carbomer obtained by this invention has a uniform molecular structure, a large molecular weight, and its molecular chain segments are easily neutralized and opened in the aqueous phase. Therefore, it not only has high viscosity (60,000-110,000 mPa·s) but also high transparency in the aqueous phase and good structural stability. The carbomer prepared by this invention does not contain toxic metal ions or other toxic substances and has good application potential in biomedicine and cosmetics.

[0026] (3) The preparation method of carbomer in this invention is simple and rapid, requiring no heating and no water bath cooling, thus reducing energy consumption and allowing for more precise temperature control. The reaction temperature is precisely controlled by adjusting the power of the ultraviolet lamp and the addition of the thermal initiator during the reaction process, ensuring safety and zero pollution. This invention obtains carbomer materials with different UV resistance, viscosity, and transparency by adjusting the power of the ultraviolet lamp, the initiator dosage, solvent ratio, type and amount of crosslinking agent, and reaction time. Detailed Implementation

[0027] The present invention will be further described in detail below through preferred specific embodiments. These specific embodiments are merely illustrative of the invention, but the scope of protection of the invention is not limited thereto.

[0028] In addition, the experimental methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0029] The sources of each raw material in the implementation list are as follows:

[0030] Acrylic acid: Wanhua Chemical Group Co., Ltd.

[0031] Hypermer B246: Shanghai Kaiyin Chemical Co., Ltd.

[0032] Pentaerythritol Triallyl Ether: Shanghai Maclean Biotechnology Co., Ltd.

[0033] Ethyl acetate: Shandong Fuyu Chemical Co., Ltd.

[0034] Cyclohexane: Shandong Fuyu Chemical Co., Ltd.

[0035] n-Hexane: Shandong Fuyu Chemical Co., Ltd.

[0036] Benzoyl peroxide: Shanghai Maclean Biotechnology Co., Ltd.

[0037] Pentaerythritol tetra-3-mercaptopropionate: Saen Chemical Technology (Shanghai) Co., Ltd.

[0038] diallyl phthalate: Shanghai Maclean Biochemical Technology Co., Ltd.

[0039] Octadecyl mercaptan: Shanghai Maclean Biochemical Technology Co., Ltd.

[0040] Ethylene dithiol: Saen Chemical Technology (Shanghai) Co., Ltd.

[0041] Carboxymethyl cellulose: Shanghai Maclean Biochemical Technology Co., Ltd.

[0042] Allyl sucrose ethers: Saen Chemical Technology (Shanghai) Co., Ltd.

[0043] Sodium dodecyl sulfate: Shanghai Maclean Biochemical Technology Co., Ltd.

[0044] Benzophenone: Shanghai Maclean Biochemical Technology Co., Ltd.

[0045] Benzoin Isopropyl Ether: Shanghai Maclean Biochemical Technology Co., Ltd.

[0046] Example 1

[0047] (1) 20g of acrylic acid, 0.06g of benzoin dimethyl ether, 0.04g of Hypermer B246, and 0.1g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and cyclohexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.06g of thermal initiator benzoyl peroxide was added. The system temperature was maintained at 70-72℃ by adjusting the UV lamp power. After reacting for 3 hours, 0.08g of pentaerythritol tetra-3-mercaptopropionate was added dropwise, and the reaction was carried out for 1 hour, finally yielding a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0048] (2) The viscous emulsion is filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried at 90°C for 8 hours in a vacuum drying oven to obtain powdered carbomer material.

[0049] Example 2

[0050] (1) 20g of acrylic acid, 0.04g of benzoin isopropyl ether, 0.12g of Hypermer B246, and 0.1g of allyl sucrose ether were added to a 200mL mixture of ethyl acetate and cyclohexane (volume ratio 1.3:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.1g of benzoyl peroxide was added. The system temperature was maintained at 70-72℃ by adjusting the UV lamp power. After reacting for 3 hours, 0.2g of pentaerythritol tetra-3-mercaptopropionate was added dropwise, and the reaction was carried out for 2 hours to obtain a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0051] (2) The viscous emulsion is filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried at 95°C for 9 hours in a vacuum drying oven to obtain powdered carbomer material.

[0052] Example 3

[0053] (1) 30g of acrylic acid, 0.1g of benzophenone, 0.06g of sodium dodecyl sulfate, and 0.05g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and n-hexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.06g of benzoyl peroxide was added. The system temperature was maintained at 70-72℃ by adjusting the UV lamp power. After reacting for 2 hours, 0.12g of pentaerythritol tetra-3-mercaptopropionate was added dropwise. After reacting for another 2 hours, a viscous emulsion was finally obtained. The above reaction was carried out in a 250mL three-hole flask.

[0054] (2) Filter the viscous emulsion, wash it three times with a mixed solution of ethyl acetate and cyclohexane, and then dry it in a vacuum drying oven at 100°C for 9 hours to obtain powdered carbomer material.

[0055] Example 4

[0056] (1) 50g of acrylic acid, 0.1g of benzoin dimethyl ether, 0.3g of Hypermer B246, and 0.05g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and cyclohexane (volume ratio 1.5:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.10g of benzoyl peroxide was added. The system temperature was maintained at 70-72℃ by adjusting the UV lamp power. After reacting for 2 hours, 0.005g of ethylene dithiol was added dropwise, and the reaction was continued for 1 hour, finally yielding a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0057] (2) The viscous emulsion was filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried in a vacuum drying oven at 100°C for 8 hours to obtain powdered carbomer material.

[0058] Example 5

[0059] (1) 20g of acrylic acid, 0.1g of benzoin dimethyl ether, 0.12g of sodium dodecyl sulfate, and 0.002g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and cyclohexane (volume ratio 1.5:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.04g of benzoyl peroxide was added dropwise. The system temperature was maintained at 70-72℃ by adjusting the UV lamp power. After reacting for 3 hours, 0.1g of pentaerythritol tetra-3-mercaptopropionate was added dropwise, and the reaction was carried out for 1 hour, finally yielding a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0060] (2) The viscous emulsion was filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried in a vacuum drying oven at 95°C for 8 hours to obtain powdered carbomer material.

[0061] Example 6

[0062] (1) 20g of acrylic acid, 0.06g of benzoin dimethyl ether, 0.12g of carboxymethyl cellulose, and 0.1g of diallyl phthalate were added to a 200mL mixture of ethyl acetate and cyclohexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with ultraviolet light. After the system temperature reached 70℃, 0.06g of benzoyl peroxide was added. The system temperature was maintained at 70-72℃ by adjusting the power of the ultraviolet light. After reacting for 3 hours, 0.08g of pentaerythritol tetra-3-mercaptopropionate was added dropwise, and the reaction was allowed to proceed for 0.5 hours, resulting in a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0063] (2) Filter the viscous emulsion, wash it three times with a mixed solution of ethyl acetate and cyclohexane, and then dry it in a vacuum drying oven at 100°C for 9 hours to obtain powdered carbomer material.

[0064] Comparative Example 1

[0065] (1) 20g of acrylic acid, 0.06g of benzoin dimethyl ether, 0.04g of Hypermer B246, and 0.1g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and cyclohexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.06g of benzoyl peroxide was added. The system temperature was maintained at 70-72℃ by adjusting the UV lamp power. The reaction was carried out for 4 hours, and a viscous emulsion was finally obtained. The above reaction was carried out in a 250mL three-hole flask.

[0066] (2) The viscous emulsion is filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried at 90°C for 8 hours in a vacuum drying oven to obtain powdered carbomer material.

[0067] Comparative Example 2

[0068] (1) 20g of acrylic acid, 0.06g of benzoin dimethyl ether, 0.04g of Hypermer B246, and 0.1g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and cyclohexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.06g of benzoyl peroxide was added. The system temperature was maintained at 70-72℃ by adjusting the UV lamp power. After reacting for 3 hours, 0.08g of octadecyl mercaptan was added dropwise, and the reaction was continued for 1 hour, finally yielding a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0069] (2) The viscous emulsion was filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried in a vacuum drying oven at 90°C for 8 hours to obtain powdered carbomer material.

[0070] Comparative Example 3

[0071] (1) 20g of acrylic acid, 0.06g of benzoin dimethyl ether, 0.04g of Hypermer B246, and 0.1g of pentaerythritol triallyl ether were added to a 200mL mixture of ethyl acetate and cyclohexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 70℃, 0.06g of benzoyl peroxide was added. The UV lamp power was kept constant, and the temperature was not controlled. After 2 hours of reaction, 0.08g of pentaerythritol tetra-3-mercaptopropionate was added dropwise, and the reaction was carried out for 1 hour, finally yielding a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0072] (2) Filter the viscous emulsion, wash it three times with a mixed solution of ethyl acetate and cyclohexane, and then dry it in a vacuum drying oven at 90°C for 9 hours to obtain powdered carbomer material.

[0073] Comparative Example 4

[0074] (1) 20g of acrylic acid, 0.06g of benzoin dimethyl ether, 0.04g of Hypermer B246, and 0.1g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and cyclohexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with ultraviolet light. After the system temperature reached 65℃, 0.06g of benzoyl peroxide was added. The system temperature was maintained at 65-67℃ by adjusting the power of the ultraviolet light. After reacting for 3 hours, 0.08g of pentaerythritol tetra-3-mercaptopropionate was added dropwise, and the reaction was carried out for 1 hour to obtain an emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0075] (2) The viscous emulsion is filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried at 90°C for 8 hours in a vacuum drying oven to obtain powdered carbomer material.

[0076] Comparative Example 5

[0077] (1) 20g of acrylic acid, 0.06g of benzoin dimethyl ether, 0.04g of Hypermer B246, and 0.1g of pentaerythritol triallyl ether were added to a mixed solvent of 200mL of ethyl acetate and cyclohexane (volume ratio 1.25:1). Argon gas was introduced, the mixture was mechanically stirred, and irradiated with a UV lamp. After the system temperature reached 80℃, 0.06g of benzoyl peroxide was added. The system temperature was maintained at 80-82℃ by adjusting the UV lamp power. After reacting for 3 hours, 0.08g of pentaerythritol tetra-3-mercaptopropionate was added dropwise, and the reaction was carried out for 1 hour, finally yielding a viscous emulsion. The above reaction was carried out in a 250mL three-hole flask.

[0078] (2) The viscous emulsion is filtered, washed three times with a mixed solution of ethyl acetate and cyclohexane, and then dried at 90°C for 8 hours in a vacuum drying oven to obtain powdered carbomer material.

[0079] A. Basic Performance

[0080] Scent evaluation: Ten members of the scent evaluation team will be recruited to rate the scent of the lotion (on a scale of 1-5), with 1 being the worst and 5 being the best.

[0081] B. Aqueous Phase Performance Evaluation

[0082] Aqueous sample preparation: Take 1g of carbomer and add it to 99g of water, then neutralize it with 18% NaOH aqueous solution to pH=7.5, and test the transparency and viscosity at this point.

[0083] Transparency Test: After the transparency instrument completes its self-test, allow it to warm up for 20 minutes. Determine the wavelength to 420nm, perform zero-calibration using pure water as a reference, then place the sample in the instrument and read the transparency value.

[0084] Viscosity test: After the system self-test is completed, place the container containing the sample on the container stand, select 20 rpm, immerse the rotor in the sample, and ensure the mark on the agitator blade shaft is flush with the liquid surface. The instrument will start running automatically, and the viscosity value will be read after a few seconds once the data stabilizes.

[0085] UV resistance test: Select a 100W UV aging chamber, place the prepared aqueous viscosity test sample inside, retest the viscosity after 14 days, and calculate the viscosity retention rate compared to before UV irradiation.

[0086]

Claims

1. A method for preparing a carbomer, characterized by, The method comprises the following steps: (1) adding acrylic monomer into mixed solvent, blowing in inert gas, then adding photo initiator, dispersant and polyene crosslinking agent, stirring under UV lamp for a period of time, then adding thermal initiator dropwise, reacting for a period of time, adding polythiol crosslinking agent, and continuing to react while controlling the reaction temperature; the thermal initiator is selected from benzoyl peroxide; (2) filtering and washing the reaction product, and drying to obtain carbomer; In the step (1), the polythiol crosslinking agent is selected from one or more of ethanedithiol, 1,3-propanedithiol and pentaerythritol tetra-3-mercaptopropionate In the step (1), the reaction temperature is 70-72℃.

2. The method of claim 1, wherein, In the step (1), the photo initiator is selected from one or more of benzophenone, benzoin isopropyl ether, diphenyl ketone, benzoin dimethyl ether and benzoin ethyl ether.

3. The method of claim 1, wherein, In the step (1), the polyene crosslinking agent is selected from one or more of pentaerythritol triallyl ether, allyl sucrose ether, diallyl phthalate and methylene bisacrylamide.

4. The method according to any one of claims 1 to 3, characterized in that, In the step (1), the wavelength of the UV lamp is 320-395nm, and the power is 0.01W-50W; and / or, the stirring speed is 250-750rpm / min, the reaction time under the UV lamp is 1h-4h; and / or, the reaction time after the thermal initiator is added dropwise is 1-3h, and the reaction time after the polythiol crosslinking agent is added dropwise is 0.5-2h.

5. The method according to any one of claims 1 to 3, wherein In the step (1), the mixed solvent is two or more of ethyl acetate, cyclohexane, n-hexane and chloroform.

6. The method according to any one of claims 1 to 3, wherein In the step (1), the dispersant is one or more of polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, sodium dodecyl sulfate, alkylphenol polyoxyethylene ether and Hypermer B246.

7. The method of any one of claims 1-3, wherein, In the step (1), the concentration of the acrylic monomer in the mixed solvent is 0.1-0.5g / ml; and / or, the amount of the dispersant added is 0.2%-0.6% of the mass of the acrylic monomer; and / or, the amount of the polyene crosslinking agent added is 0.01%-1% of the mass of the acrylic acid; and / or, the amount of the polythiol crosslinking agent added is 0.01%-1% of the mass of the acrylic acid.

8. The method of any one of claims 1-3, wherein, In the step (2), the washing solvent is one or both of ethyl acetate and cyclohexane, and the washing times are 3-4 times; the drying process is one of vacuum drying, normal pressure drying and radiation drying, the drying temperature is 80-110℃, and the drying time is 7-10h.

9. A carbomer prepared by the method of any one of claims 1-8.

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