Water and oil repellent emulsion for textiles and process for its preparation

Abstract

The application relates to a waterproof and oil-proof emulsion for textiles and a preparation method thereof. The waterproof and oil-proof agent composition contains a fluorine-containing copolymer, deionized water, an emulsifier and a cosolvent. The fluorine-containing copolymer is copolymerized from a monomer composition which comprises a fluorine-containing monomer, a long-chain alkyl methacrylate with multiple methyl groups on the long-chain alkyl side chain and a crosslinking monomer. The fluorine-containing monomer is perfluorohexyl ethyl methacrylate. The long-chain alkyl methacrylate with multiple methyl groups on the long-chain alkyl side chain is 3,7,11,15-tetramethyl-hexadecyl methacrylate. The crosslinking monomer is an acrylic acid monomer with two functional groups. The waterproof performance of the emulsion is greatly improved, is superior to a C6 product on the market, and has reached the effect of a commercially available C8 waterproof agent. The fabric treated by the waterproof agent has a good hand feeling.

Description

Technical Field

[0001] The present application relates to the field of textile auxiliaries, and is a waterproof and oil-proof emulsion for textiles and a preparation method thereof. Background Art

[0002] As we all know, the mainstream water and oil repellent in the textile industry is still fluorinated acrylic emulsions. Although non-fluorinated water repellents, such as paraffin and silicone-based water repellents, have appeared on the market in recent years, their performance still cannot match that of fluorinated water repellents, and they have almost no oil repellency.

[0003] Currently, the non-fluorine-containing water repellent market share is less than 10%, and fluorine-containing water repellents are still the preferred choice for customers. Currently, C8 water and oil repellents are the main type of fluorine-containing water repellents. This is mainly because the side chains of the 8-carbon fluorine-containing monomers can crystallize, resulting in better water and oil repellency.

[0004] Current research results indicate that it is not the static contact angle but the dynamic contact angle, especially the receding contact angle, that is crucial in determining surface properties. Due to the crystallinity of the 8-carbon side chain monomer, its receding contact angle is significantly higher than that of short-chain fluorinated monomers with 7 or fewer carbon atoms. However, since the 8-carbon fluorinated monomer can transform into PFOA, PFOA has been shown to be highly bioaccumulative and difficult to degrade. Many countries and regions have enacted relevant laws to ban its use, and many companies have stopped selling water repellents containing 8-carbon fluorinated monomers. However, due to the inherent defects of the fluorinated monomers in short-chain fluorinated emulsions with 7 or fewer carbon atoms, their performance cannot meet customer needs. Therefore, improving the water and oil repellency of short-chain fluorinated emulsions is an urgent issue that needs to be addressed.

[0005] Chinese patent publication number CN103184690A discloses a surface treatment agent and its manufacturing method. This surface treatment agent modifies a conventional C6 fluorinated monomer, replacing the α-methyl group on the vinyl group with a chlorine atom. This reduces the mobility of the fluorinated monomer's side chain, thereby increasing its dynamic receding contact angle. While this method improves the water repellency of the water repellent compared to emulsions made with conventional C6 monomers, it also increases the polymer's glass transition temperature, making the treated fabric hard and lacking in feel. Furthermore, the new monomer is significantly more expensive than the original, significantly increasing costs and making its widespread use difficult. Another example is the C4 monomer used by 3M, which, due to its shorter fluorinated side chain, performs worse than conventional C6 monomer water repellents. Few such water repellents are commercially available.

[0006] Separately, Chinese patent publication number CN102459494A discloses a water- and oil-repellent composition, its production method, and article treatment method. This composition optimizes the performance of short-chain C6 monomers by modifying the non-fluorinated comonomer. They use behenyl acrylate instead of octadecyl acrylate, commonly used in C8 water repellents. While the performance of emulsions formed by copolymerizing short-chain C6 monomers with octadecyl acrylate is improved, it still lags behind C8 water repellents.

[0007] Therefore, the market is in urgent need of a short-chain fluorine-containing waterproofing agent with performance comparable to that of C8 waterproofing agent. Summary of the Invention

[0008] The purpose of the present invention is to provide a textile emulsion with excellent waterproof and oil-proof functions and a preparation method thereof, wherein the performance of the waterproof and oil-proof emulsion can reach the level of traditional C8 waterproofing agent.

[0009] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions on the one hand: a waterproof and oil-proof emulsion for textiles, comprising the following components in parts by mass: 10-30 parts by mass of a fluorinated copolymer, 50-70 parts by mass of deionized water, 0.1-10 parts by mass of an emulsifier, and 0.1-10 parts by mass of a cosolvent; the fluorinated copolymer is copolymerized by a monomer composition, and the monomer composition includes monomer components in the following proportions: 40-70 parts by mass of a fluorinated monomer, 0.1-3 parts by mass of a cross-linking monomer, and 10-60 parts by mass of a methacrylate monomer having a long-chain alkyl group and multiple methyl groups on the long-chain alkyl side chain; wherein the fluorinated monomer is perfluorohexylethyl methacrylate, the cross-linking monomer is an acrylate monomer and / or an acrylamide monomer containing at least one C=C double bond group and at least one reactive group, the at least one reactive group comprising a group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and an epoxy group, and the methacrylate monomer having a long-chain alkyl group and multiple methyl groups on the long-chain alkyl side chain has a structure represented by the following general formula:

[0010]

[0011] In the above technical solution, the monomer composition may further include: 0.1-20 parts by mass of a chlorine-containing ethylene monomer; wherein the chlorine-containing ethylene monomer is vinyl chloride or vinylidene chloride monomer.

[0012] In the above technical solution, the emulsifier composition is preferably composed of a cationic emulsifier and a nonionic emulsifier; wherein the mass fraction of the cationic emulsifier in the emulsifier composition is 30-60%, and the structural formula is R(CH3)3N + X -, wherein R is a long-chain alkyl group of 12-18, and X is a halogen atom of chlorine or bromine; the nonionic emulsifier is a surfactant with an alkyl polyoxyethylene ether structure, with the general formula RO(CH2CH2O)nH, wherein R is a long-chain alkyl group of 12-20, and n is 3-50. The mass fraction of the nonionic emulsifier in the emulsifier composition is 40-70%.

[0013] In the above technical solution, the cosolvent is preferably an alcohol solvent having a boiling point greater than or equal to 180° C. More preferably, the cosolvent is selected from at least one of propylene glycol, dipropylene glycol, and tripropylene glycol.

[0014] In the above technical solution, preferably, the acrylate monomer is selected from at least one of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, epoxy (meth)acrylate, diacetone (meth)acrylamide, N-methylol acrylamide, 3-chloro-2-hydroxypropyl (meth)acrylate, and glycidyl (meth)acrylate; and the acrylamide monomer is selected from at least one of diacetone (meth)acrylamide and N-methylol acrylamide.

[0015] Another aspect of the present application provides a method for preparing a waterproof and oil-proof emulsion for textiles, the method comprising the following steps:

[0016] 1) Weighing the monomers of the fluorinated copolymer, ionized water, emulsifier, and cosolvent as needed, preheating them in a water bath at 55-65° C. for 30-60 minutes, pre-dispersing them under mechanical stirring, and finally homogenizing them in a high-pressure homogenizer to obtain a metastable emulsion with a particle size of less than 200 nm;

[0017] 2) introducing the metastable emulsion obtained in step 1) into a reaction vessel, adding a chain transfer agent and an initiator, heating to 50-80° C., carrying out a polymerization reaction for 3-6 hours, finally cooling to room temperature and filtering to obtain the waterproof and oil-proof emulsion; wherein the weight ratio of the added chain transfer agent to the weight of the fluorinated copolymer weighed in step 1) is 0.1-0.5:100, and the weight ratio of the added initiator to the weight of the fluorinated copolymer weighed in step 1) is 0.4-2.0:100.

[0018] In the above technical solution, the chain transfer agent is preferably dodecyl mercaptan.

[0019] In the above technical solution, the initiator is preferably one of water-soluble azobisisobutylamidine hydrochloride, ammonium persulfate, potassium persulfate, or a combination of at least two thereof; or an oil-soluble initiator of the azo or peroxide type.

[0020] In the above technical solution, the monomer composition further includes: 0.1-20 parts by mass of a chlorine-containing ethylene monomer; wherein the chlorine-containing ethylene monomer is vinyl chloride or vinylidene chloride; the method further includes: in step 2), after adding the chain transfer agent and initiator, adding the chlorine-containing ethylene monomer, and then heating to 50-80°C.

[0021] Compared to the prior art, the technical effects of this application are as follows: the excellent waterproof and oil-proof emulsion obtained by the present invention introduces a C6 monomer (perfluorohexylethyl methacrylate) and a functional comonomer (3,7,11,15-tetramethyl-hexadecyl methacrylate), thereby producing the following effects: the fluorine monomer used in this application is perfluorohexylethyl methacrylate, and there are no C8 and above components with strong environmental accumulation; the key raw material used in this application is 3,7,11,15-tetramethyl-hexadecyl methacrylate as the main non-fluorine comonomer, replacing conventional octadecyl acrylate or behenyl acrylate. Due to the multiple methyl groups on its long side chain, this monomer, after copolymerization with a short-chain fluorine monomer, has a dynamic contact angle that is significantly better than that of the copolymer formed by octadecyl acrylate or behenyl acrylate and a short-chain fluorine monomer, and its performance is comparable to that of a C8 water repellent. After being treated with the product of this application, the textile fabric has a good feel, and there is no situation where performance is improved but feel is reduced. DETAILED DESCRIPTION

[0022] The present invention is further described below with reference to Examples and Comparative Examples, but is not limited thereto.

[0023] The raw materials used in the following examples and comparative examples are all commercially available industrial products and can be purchased through commercial channels.

[0024] Example 1

[0025] Add the following components into a 500ml plastic beaker: CH2=C(CH3)-C(=O)-O-CH2CH2-C6F 13 (C6FMA) 40g, 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) 59g, N-hydroxymethyl acrylamide (NMA) 1g, nonionic emulsifier C 12 H 25 O(CH2CH2O) 20 H 6g, cationic emulsifier C 18 H 37 N + (CH3)3CL -4g, tripropylene glycol 20g, deionized water 200g, then placed in a 60℃ water bath and heated for 40 minutes, dispersed in a disperser for 2 minutes at a speed of 2000rpm / m, and then placed in a high-pressure homogenizer for 10 minutes at a homogenization pressure of 400kg to obtain a metastable oil-in-water miniemulsion with a particle size of 150nm.

[0026] The metastable emulsion was then poured into a glass reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen. 0.5 g of azobisisobutylamidine hydrochloride and 0.2 g of dodecyl mercaptan were then added. The water temperature was simultaneously raised to 75°C. After six hours of reaction, a stable aqueous polymer dispersion, the target water- and oil-repellent emulsion, was obtained. GC analysis indicated a monomer conversion rate exceeding 99%.

[0027] Example 2

[0028] Add the following components into a 500ml plastic beaker: CH2=C(CH3)-C(=O)-O-CH2CH2-C6F 13 (C6FMA) 40g, 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) 37g, N-hydroxymethyl acrylamide (NMA) 3g, nonionic emulsifier C 12 H 25 O(CH2CH2O) 20 H6g, cationic emulsifier C 18 H 37 N + (CH3)3CL - 4g, tripropylene glycol 20g, deionized water 200g, then placed in a 60℃ water bath for 40 minutes, dispersed in a disperser for 2 minutes at a speed of 2000rpm / m, and then placed in a high-pressure homogenizer for 10 minutes at a homogenization pressure of 400kg to obtain a metastable oil-in-water miniemulsion with a particle size of 140nm.

[0029] The metastable emulsion was then poured into an autoclave equipped with a stirrer. After nitrogen substitution, 0.5 g of azobisisobutylamidine hydrochloride (initiator) and 0.2 g of dodecyl mercaptan (chain transfer agent) were added, followed by 20 g of vinyl chloride (VCM). The water temperature was then raised to 75°C. After six hours of reaction, a stable aqueous polymer dispersion, the target water- and oil-repellent emulsion, was obtained. GC analysis showed a monomer conversion rate exceeding 99%.

[0030] Example 3

[0031] Add the following components into a 500ml plastic beaker: CH2=C(CH3)-C(=O)-O-CH2CH2-C6F 13(C6FMA) 70g, 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) 10g, N-hydroxymethyl acrylamide (NMA) 1g, nonionic emulsifier C 12 H 25 O(CH2CH2O) 20 H6g, cationic emulsifier C 18 H 37 N + (CH3)3CL - 4g, tripropylene glycol 20g, deionized water 200g, then placed in a 60℃ water bath for 40 minutes, dispersed in a disperser for 2 minutes at a speed of 2000rpm / m, and then placed in a high-pressure homogenizer for 10 minutes at a homogenization pressure of 400kg to obtain a metastable oil-in-water miniemulsion with a particle size of 165nm.

[0032] The metastable emulsion was then poured into an autoclave equipped with a stirrer. After nitrogen displacement, 0.5 g of azobisisobutylamidine hydrochloride (initiator) and 0.2 g of dodecyl mercaptan (chain transfer agent) were added, followed by the addition of 19 g of vinyl chloride (VCM). The water temperature was then raised to 75°C and allowed to react for 6 hours to obtain a stable aqueous polymer dispersion, the target water- and oil-repellent emulsion. GC analysis showed a monomer conversion rate exceeding 99%.

[0033] Example 4

[0034] Add the following components into a 500ml plastic beaker: CH2=C(CH3)-C(=O)-O-CH2CH2-C6F 13 (C6FMA) 55g, 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) 32g, N-hydroxymethyl acrylamide (NMA) 3g, nonionic emulsifier C 12 H 25 O(CH2CH2O) 20 H6g, cationic emulsifier C 18 H 37 N + (CH3)3CL - 4g, tripropylene glycol 20g, deionized water 200g, then placed in a 60℃ water bath for 40 minutes, dispersed in a disperser for 2 minutes at a speed of 2000rpm / m, and then placed in a high-pressure homogenizer for 10 minutes at a homogenization pressure of 400kg to obtain a metastable oil-in-water miniemulsion with a particle size of 110nm.

[0035] The metastable emulsion was then poured into an autoclave equipped with a stirrer. After nitrogen substitution, 0.5 g of azobisisobutylamidine hydrochloride (initiator) and 0.2 g of dodecyl mercaptan (chain transfer agent) were added, followed by 10 g of vinyl chloride (VCM). The water temperature was then raised to 75°C and allowed to react for 6 hours to obtain a stable aqueous polymer dispersion, the target water- and oil-repellent emulsion. GC analysis showed a monomer conversion rate exceeding 99%.

[0036] Comparative Example 1

[0037] The raw material 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) was replaced with octadecyl acrylate (C18A). Other raw materials and preparation steps were the same as those in Example 1 to obtain the desired emulsion of Comparative Example 1.

[0038] Comparative Example 2

[0039] The raw material 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) was replaced with octadecyl acrylate (C18A). Other raw materials and preparation steps were the same as those in Example 2 to obtain the desired emulsion of Comparative Example 2.

[0040] Comparative Example 3

[0041] The raw material 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) was replaced with behenyl acrylate (C22A). Other raw materials and preparation steps were the same as those in Example 1 to obtain the desired emulsion of Comparative Example 3.

[0042] Comparative Example 4

[0043] The raw material 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) was replaced with behenyl acrylate (C22A). Other raw materials and preparation steps were the same as those in Example 2 to obtain the desired emulsion of Comparative Example 4.

[0044] Comparative Example 5

[0045] The raw material CH2=C(CH3)-C(=O)-O-CH2CH2-C6F 13 (C6FMA) was changed to CH2=C(H)-C(=O)-O-CH2CH2-C8F 17 (C8FA), 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) was replaced by octadecyl acrylate (C18A), and other raw materials and preparation steps were the same as those in Example 1 to obtain the desired emulsion of Comparative Example 5.

[0046] Comparative Example 6

[0047] The raw material CH2=C(H)-C(=O)-O-CH2CH2-C8F 17 (C8FA) is changed to CH2=C(CI)-C(=O)-O-CH2CH2-C6F 13 (C6FCIA), other raw materials and preparation steps were the same as those in Comparative Example 5 to obtain the desired emulsion of Comparative Example 6.

[0048] Comparative Example 7

[0049] The raw material 3,7,11,15-tetramethyl-hexadecyl methacrylate (4M-C16MA) was replaced with isooctyl methacrylate (the side chain of EHMA is a short-chain alkyl group with only one methyl group), and the other raw materials and preparation steps were the same as those in Example 1 to obtain the desired emulsion of Comparative Example 7.

[0050] In the above embodiments and comparative examples, the amounts of various monomers in the fluorine-containing copolymers are shown in Table 1 below. The unit of measurement for the amounts of various monomers in the table is gram.

[0051] Table 1

[0052]

[0053] Examples 1-4 and Comparative Examples 1-7, commercial product A (C8 water repellent), and commercial product B (C6 water repellent) were evaluated for their water and oil repellency and hand feel.

[0054] The test was conducted on three fabrics at a concentration of 2.0%, using a one-dip and one-dry method, at 170°C, drying for one minute, and then conducting water and oil repellency evaluation. The details are as follows:

[0055] Water repellency test

[0056] The test standard is AATCC-22. Using a water spray test device, 250ml of tap water is poured onto the test object within 25 seconds. The wetting state of the fabric is observed and the water repellency is evaluated. The test results are as follows:

[0057] 100 points: The surface is not wetted and water droplets do not adhere;

[0058] 90 points: The surface is not wet, but there are small water droplets attached;

[0059] 80 points: The surface is wet in the form of water droplets;

[0060] 70 points: The surface is quite partially wetted;

[0061] 50 points: The surface is almost completely wetted;

[0062] 0 points: Both the front and back sides are moistened.

[0063] Oil repellency test

[0064] The test standard is AATCC-118 method: First, carefully drop five drops of 0.05mL of the lowest-numbered test liquid onto the sample. If no penetration or wetting occurs within 30 seconds, then drop the higher-numbered test liquid onto the sample. The test continues until the test liquid wets the sample below or around the drop within 30 seconds. The oil repellency level of the sample is represented by the highest-numbered test liquid that fails to wet the sample within 30 seconds. The rating is shown in the following table. See Table 2 for oil repellency test liquids.

[0065] [Table 2]

[0066] Oil resistance level Components Surface tension (mN / m, 25°C) 1 White mineral oil 31.2 2 65 parts of white mineral oil + 35 parts of n-hexadecane 28.7 3 n-Hexadecane 27.1 4 n-Tetradecane 26.1 5 n-Dodecane 25.1 6 n-decane 23.5 7 n-octane 21.3 8 n-heptane 19.8

[0067] Hand feel test

[0068] After the fabric to be tested was placed in a constant temperature and humidity room at 25°C ± 2°C and 65% ± 2% for 24 hours, the softness was determined by hand sensory evaluation using the following criteria: 0: soft; △: average; ×: hard. The test results are shown in Table 3.

[0069] Table [3]

[0070]

[0071] In summary, the use of 4,7,11,15-tetramethyl-hexadecyl methacrylate monomer to replace octadecyl acrylate or behenyl acrylate has significantly better waterproof and oil-proof properties than the products of the latter two copolymerized with fluorine monomers, and is close to or reaches the effect of the commercially available C8 waterproof agent; at the same time, the fabric feels soft, and there is no situation like Comparative Example 6 where the waterproof performance is improved but the hand feel is reduced; in addition, the fluorine-containing emulsion formed by EHMA with a short side chain and only one methyl group in the side chain has the worst waterproof performance and cannot meet customer requirements.

[0072] The above embodiments are intended only to illustrate the technical concepts and features of this application. Their purpose is to enable those familiar with the art to understand the content of this application and implement it accordingly. They are not intended to limit the scope of protection of this application. Any equivalent changes or modifications made in accordance with the spirit of this application shall be included in the scope of protection of this application.

Claims

1. A waterproof and oil-proof emulsion for textiles, comprising the following components in parts by mass: 10-30 parts by mass of a fluorinated copolymer, 50-70 parts by mass of deionized water, 0.1-10 parts by mass of an emulsifier, and 0.1-10 parts by mass of a cosolvent; characterized in that: The fluorine-containing copolymer is formed by copolymerization of a monomer composition, which includes monomer components in the following proportions: 40-70 parts by mass of a fluorine-containing monomer, 0.1-3 parts by mass of a cross-linking monomer, and 10-60 parts by mass of a methacrylate monomer having a long-chain alkyl group and multiple methyl groups on the long-chain alkyl side chain; wherein the fluorine-containing monomer is perfluorohexylethyl methacrylate, the cross-linking monomer is an acrylate monomer and / or an acrylamide monomer containing at least one C=C double bond group and at least one reactive group, wherein the at least one reactive group comprises a group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and an epoxy group, and the methacrylate monomer having a long-chain alkyl group and multiple methyl groups on the long-chain alkyl side chain has a structure represented by the following general formula:

2. The waterproof and oil-proof emulsion for textile use according to claim 1, characterized in that The monomer composition further comprises: 0.1-20 parts by weight of a chlorine-containing ethylene monomer; wherein the chlorine-containing ethylene monomer is vinyl chloride or vinylidene chloride.

3. The waterproof and oil-proof emulsion for textile use according to claim 1, characterized in that: The emulsifier is composed of a cationic emulsifier and a nonionic emulsifier; wherein the mass fraction of the cationic emulsifier in the emulsifier is 30-60%, and the structural formula is R(CH3)3N + X - , wherein R is a long-chain alkyl group of 12-18, and X is a halogen atom of chlorine or bromine; the nonionic emulsifier is a surfactant with an alkyl polyoxyethylene ether structure, with the general formula RO(CH2CH2O)nH, wherein R is a long-chain alkyl group of 12-20, and n is 3-50. The mass fraction of the nonionic emulsifier in the emulsifier is 40-70%.

4. The waterproof and oil-proof emulsion for textile use according to claim 1, characterized in that The co-solvent is an alcohol solvent with a boiling point greater than or equal to 180°C.

5. The waterproof and oil-proof emulsion for textile use according to claim 4, characterized in that: The cosolvent is selected from at least one of propylene glycol, dipropylene glycol and tripropylene glycol.

6. The waterproof and oil-proof emulsion for textile use according to claim 1, characterized in that: The acrylate monomer is selected from at least one of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, epoxy (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate and glycidyl (meth)acrylate; and the acrylamide monomer is selected from at least one of diacetone (meth)acrylamide and N-hydroxymethyl acrylamide.

7. A method for preparing the waterproof and oil-proof emulsion for textile use according to any one of claims 1, 3-6, characterized in that: The method comprises the following steps: 1) Weighing the monomers of the fluorinated copolymer, deionized water, emulsifier, and cosolvent as needed, preheating them in a water bath at 55-65° C. for 30-60 minutes, pre-dispersing them under mechanical stirring, and finally homogenizing them in a high-pressure homogenizer to obtain a metastable emulsion with a particle size of less than 200 nm; 2) introducing the metastable emulsion obtained in step 1) into a reaction vessel, adding a chain transfer agent and an initiator, heating to 50-80° C., carrying out a polymerization reaction for 3-6 hours, finally cooling to room temperature and filtering to obtain the waterproof and oil-proof emulsion; wherein the weight ratio of the added chain transfer agent to the weight of the fluorinated copolymer weighed in step 1) is 0.1-0.5:100, and the weight ratio of the added initiator to the weight of the fluorinated copolymer weighed in step 1) is 0.4-2.0:

100.

8. The method according to claim 7, characterized in that The chain transfer agent is dodecyl mercaptan.

9. The method according to claim 7, characterized in that The initiator is one of water-soluble azobisisobutylamidine hydrochloride, ammonium persulfate, potassium persulfate, or a combination of at least two thereof; or an azo-type or peroxide-type oil-soluble initiator.

10. The method according to claim 7, characterized in that The monomer composition for copolymerizing the fluorine-containing copolymer further comprises: 0.1-20 parts by mass of a chlorine-containing ethylene monomer; wherein the chlorine-containing ethylene monomer is vinyl chloride or vinylidene chloride; the method further comprises: in step 2), after adding the chain transfer agent and initiator, adding the chlorine-containing ethylene monomer, and then heating to 50-80°C.

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