Preparation method of fluorine-containing emulsion, fluorine-containing surface protective agent and application thereof

Abstract

The present invention provides a method for preparing a fluorine-containing emulsion, firstly adopting solution polymerization to obtain a vinylidene chloride oligomer solution with an epoxy group, then reacting with acrylic acid to open the epoxy group to obtain a vinylidene chloride oligomer solution with a double bond, then removing the solvent and unreacted monomers in the solution by reduced pressure distillation to obtain a vinylidene chloride oligomer with a double bond, and then using the oligomer as a monomer for emulsion polymerization to obtain a vinylidene chloride fluorine-containing emulsion with a low vinylidene chloride residual content. At the same time, the present invention provides a fluorine-containing surface protective agent containing the fluorine-containing emulsion and an application thereof in fabric finishing.

Description

Technical Field

[0001] The invention relates to the technical field of fluorine-containing polymers, and in particular to a preparation method of a fluorine-containing emulsion, a fluorine-containing surface protective agent and applications thereof. Background Art

[0002] Vinylidene chloride (VDC) usually plays a role in increasing the adhesion of fluorinated surface protective agents. However, due to its high polarity, it is difficult to dissolve in general solvents. In addition, the compatibility of vinylidene chloride monomer with other monomers is poor and the polymerization rate is quite different. Therefore, the conversion rate of vinylidene chloride is low during the emulsion polymerization of fluorinated surface protective agents. Excessive vinylidene chloride needs to be added to increase the participation of vinylidene chloride in the reaction. However, the excessive vinylidene chloride is difficult to recover and remove in the emulsion, resulting in excessive residual vinylidene chloride, which is harmful to the environment and the human body.

[0003] The existing technology often uses high-temperature vacuum extraction separation technology to remove vinylidene chloride from the emulsion, that is, a vacuum pump is used to extract the emulsion at a temperature (70-85°C) that does not destroy the emulsion. However, this technology currently has the following two defects: first, the extraction efficiency is too low, and the residual vinylidene chloride cannot be effectively removed in a short time; second, it is easy to destroy the stability of the emulsion. Extracting vinylidene chloride in this temperature range will cause a large amount of water in the emulsion to be lost, resulting in an increase in the concentration of the emulsion, causing the emulsion to precipitate solids during storage, resulting in a decrease in storage time.

[0004] Therefore, it is necessary to develop a new method for reducing the residual amount of vinylidene chloride in fluorinated surface protective agents. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for preparing a fluorine-containing emulsion, a fluorine-containing surface protective agent and application thereof. The preparation method can significantly reduce the residual amount of vinylidene chloride in the emulsion and reduce its harm to the environment and human body.

[0006] In one aspect, the present invention provides a method for preparing a fluorine-containing emulsion, comprising:

[0007] (1) adding a solvent, an initiator A, a vinylidene chloride monomer 1, a fluorinated acrylate monomer 2, and an epoxy acrylate monomer 3 into a reaction kettle, raising the temperature to perform solution polymerization, and after the polymerization is completed, adding acrylic acid and a catalyst to react to obtain a vinylidene chloride oligomer solution with double bonds;

[0008] (2) distilling the above-mentioned vinylidene chloride oligomer solution with double bonds under reduced pressure to obtain vinylidene chloride oligomer with double bonds;

[0009] (3) Add the above-mentioned vinylidene chloride oligomer with double bonds, fluorinated acrylate monomer 2, monomer 4, emulsifier, cosolvent and deionized water into a reaction kettle, heat and stir to dissolve the solid, then homogenize under high pressure, increase the temperature, add initiator B, start emulsion polymerization, and obtain the fluorinated emulsion after the reaction is completed.

[0010] The present invention firstly adopts solution polymerization to obtain a vinylidene chloride oligomer solution with epoxy groups, then reacts with acrylic acid to open the epoxy groups to obtain a vinylidene chloride oligomer solution with double bonds, then performs reduced pressure distillation to remove the solvent and unreacted monomers in the solution to obtain a vinylidene chloride oligomer with double bonds, and then uses the oligomer as a monomer for emulsion polymerization to obtain a fluorine-containing emulsion of vinylidene chloride with a low vinylidene chloride residual content.

[0011] Preferably, in the steps (1) and (3), the fluorine-containing acrylate monomer 2 is perfluorohexylethyl acrylate; the monomer 4 is selected from at least one of octadecyl acrylate, benzyl methacrylate, and N-hydroxymethyl acrylamide; the initiator A is selected from at least one of benzoyl peroxide, tert-butyl perbenzoate, and tert-butyl hydroperoxide; the initiator B is selected from at least one of azobisisobutylamidine dihydrochloride, azobisisobutylimidazoline hydrochloride, and ammonium persulfate; the emulsifier includes a cationic surfactant and a non-ionic surfactant, the cationic surfactant is preferably octadecyltrimethylammonium chloride (1831), and the non-ionic surfactant is selected from at least one of anhydrous sorbitan fatty acid esters, isomeric tridecyl alcohol polyoxyethylene ethers, and polyoxyethylene anhydrous sorbitan fatty acid esters.

[0012] In some embodiments, the monomer 4 is a combination of octadecyl acrylate, benzyl methacrylate, and N-methylol acrylamide.

[0013] Octadecanyl acrylate provides certain flexibility to the polymer main chain and certain ductility for film formation. Benzyl methacrylate provides certain rigidity to the polymer main chain structure. N-hydroxymethyl acrylamide and vinylidene chloride play a certain synergistic role, and the hydroxymethyl group can be cross-linked by heating, making the polymer main chain structure more stable.

[0014] In some embodiments, the cationic surfactant is octadecyltrimethylammonium chloride (1831), and the nonionic surfactant is a combination of sorbitan fatty acid esters, isomeric tridecyl alcohol polyoxyethylene ether, and polyoxyethylene sorbitan fatty acid esters.

[0015] In other embodiments, the mass ratio of the sorbitan fatty acid ester, the isomeric tridecyl alcohol polyoxyethylene ether, and the polyoxyethylene sorbitan fatty acid ester is 1:1:1.

[0016] 1831 is a cationic surfactant, and the structure of the surface of the fabric fiber is anionic. The two can combine well to improve the bonding ability between the polymer and the fiber; sorbitan fatty acid esters, isomeric tridecyl alcohol polyoxyethylene ethers, and polyoxyethylene sorbitan fatty acid esters are all non-ionic surfactants, which can work together with 1831 to improve the dispersion uniformity of the emulsion and thus extend the storage time of the emulsion.

[0017] Preferably, the solvent in step (1) is a benzene organic solvent, more preferably toluene.

[0018] Preferably, the solution polymerization in step (1) is carried out at 90-110° C., preferably at 105° C., and the polymerization time is 4 hours.

[0019] Preferably, before adding acrylic acid in step (1), the step further includes cooling the vinylidene chloride oligomer solution with epoxy groups obtained by solution polymerization to room temperature and then heating it to 90-95° C. At 90-95° C., under the action of a catalyst, the epoxy groups react with the carboxyl groups of acrylic acid to introduce carbon-carbon double bond groups through ring-opening esterification, and the carbon-carbon double bonds provide conditions for participating in the emulsion polymerization in the next step.

[0020] Preferably, in step (1), the catalyst is triphenylphosphine, and the insulation reaction time is 4 hours.

[0021] Preferably, the temperature of the vacuum distillation in step (2) is 90-110° C., the pressure is 95-105 mmHg, and the time is 1-2 hours. The purpose of the vacuum distillation is to remove the solvent and unreacted monomers, especially to remove the vinylidene chloride monomer.

[0022] Preferably, the heating and stirring temperature in step (3) is 35-50° C., and the pressure of the high-pressure homogenization is 30-45 MPa. The purpose of heating is: on the one hand, the stability of the homogenized pre-emulsion after heating will be higher, and on the other hand, to ensure the complete dissolution of the material.

[0023] Preferably, the cosolvent in step (3) is tripropylene glycol.

[0024] Preferably, in step (3), the emulsion polymerization temperature is 65-75°C, preferably 70°C; and the emulsion polymerization time is 7h.

[0025] Preferably, based on the sum of the weight of each reaction monomer, initiator A, solvent, acrylic acid and catalyst in step (1) being 100 weight %, the proportion of each component is:

[0026]

[0027]

[0028] In some embodiments, based on the sum of the weight of each reactive monomer, initiator A, solvent, acrylic acid and catalyst in step (1) being 100 weight %, the proportions of each component are:

[0029]

[0030] Preferably, based on the sum of the weight of each reactive monomer, emulsifier, initiator B, co-solvent and deionized water in step (3) being 100 weight %, the proportions of each component are:

[0031]

[0032] In order to ensure that the fluorine-containing emulsion has low residual vinylidene chloride content and excellent water and oil resistance, the proportion of the above vinylidene chloride oligomer with double bonds is preferably 2-3%.

[0033] In order to ensure that the fluorine-containing emulsion has low residual vinylidene chloride content and excellent water-washing resistance, the proportion of the above-mentioned vinylidene chloride oligomer with double bonds is preferably 2.5-4.5%.

[0034] In order to ensure that the fluorine-containing emulsion has low residual vinylidene chloride content and excellent water and oil resistance and water washability, the proportion of the above vinylidene chloride oligomer with double bonds is preferably 2.5-3%.

[0035] In some embodiments, based on the sum of the weight of each reactive monomer, emulsifier, initiator B, co-solvent and deionized water in step (3) being 100 weight %, the proportions of each component are:

[0036]

[0037]

[0038] In some embodiments, based on the sum of the weight of each reactive monomer, emulsifier, initiator B, co-solvent and deionized water in step (3) being 100 weight %, the proportions of each component are:

[0039]

[0040] In another aspect, the present invention provides a fluorine-containing surface protective agent, which comprises the fluorine-containing emulsion prepared by the above preparation method. The fluorine-containing surface protective agent has a low residual vinylidene chloride content.

[0041] The fluorine-containing emulsion prepared by the above preparation method can be used directly as a fluorine-containing surface protective agent, or can be used after being diluted with deionized water.

[0042] In some embodiments, the content of vinylidene chloride in the fluorinated surface protecting agent is less than 100 ppm.

[0043] In other embodiments, the content of vinylidene chloride in the fluorine-containing surface protective agent is 10-50 ppm.

[0044] In a third aspect, the present invention provides the use of the above-mentioned fluorine-containing surface protective agent on the surface of various fabrics, wherein the fabrics include pure cotton, non-pure cotton, synthetic fabrics and non-woven fabrics.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The fluorinated surface protective agent obtained by the present invention has a small amount of residual vinylidene chloride, which greatly reduces the harm to the environment and human body;

[0047] (2) The vinylidene chloride and N-hydroxymethyl acrylamide added in the present invention have a synergistic effect, which can increase the adhesion of the emulsion after film formation and improve the friction resistance;

[0048] (3) In the present invention, reduced pressure distillation is selected to obtain unreacted monomers and solvents, which can be reused to save production costs. DETAILED DESCRIPTION

[0049] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0050] Comparative Example

[0051] In a 50L reactor equipped with a thermometer, a condenser and a stirring device, 50.2kg of perfluorohexylethyl acrylate, 20kg of octadecyl acrylate, 30kg of benzyl methacrylate, 8.6kg of N-hydroxymethyl acrylamide, 8kg of vinylidene chloride, 1.3kg of octadecyltrimethylammonium chloride, 2.13kg of anhydrous sorbitan fatty acid ester, 2.13g of isomeric tridecyl alcohol polyoxyethylene ether, 2.13kg of polyoxyethylene anhydrous sorbitan fatty acid ester, 35kg of tripropylene glycol, and 258kg of deionized water were added, heated to 50°C, stirred until the solid was dissolved, and the dissolved liquid was subjected to 40MPa high-pressure homogenization to obtain a pre-emulsion.

[0052] The pre-emulsion was heated to 70° C. and stirred evenly. Then, 120 g of azobisisobutylamidine dihydrochloride and 50 kg of deionized water were added. The mixture was kept warm for 7 hours to obtain a fluorine-containing emulsion.

[0053] Example 1

[0054] (1) Add 29 kg of toluene to a 50 L reactor equipped with a thermometer, condenser and stirring device, and heat it to 105°C. Add a mixed solution of 8 kg of perfluorohexylethyl acrylate, 8 kg of vinylidene chloride, 8 kg of epoxy acrylate and 0.28 kg of benzoyl peroxide to the reactor, and control the addition to be completed within 4 hours. After the addition is completed, dissolve 20 g of benzoyl peroxide in 1 kg of toluene and add it dropwise to the reactor, keep it at 105°C for 4 hours to obtain a vinylidene chloride oligomer solution with epoxy groups, cool it to room temperature and then heat it to 90°C, slowly drip 8 kg of acrylic acid and 0.1 kg of triphenylphosphine into the solution, then raise the temperature to 95°C and keep it at 4 hours to obtain a vinylidene chloride oligomer solution with double bonds.

[0055] (2) The solution obtained in step (1) is subjected to reduced pressure distillation at 90° C. and 100 mmHg for 2 h to obtain a vinylidene chloride oligomer with a double bond.

[0056] (3) Weigh 42.2 kg of perfluorohexylethyl acrylate, 20 kg of octadecyl acrylate, 30 kg of benzyl methacrylate, 20 kg of the above-mentioned vinylidene chloride oligomer with double bonds, 8.6 kg of N-hydroxymethyl acrylamide, 1.3 kg of octadecyl trimethyl ammonium chloride, 2.13 kg of anhydrous sorbitan fatty acid ester, 2.13 kg of isomeric tridecyl alcohol polyoxyethylene ether, 2.13 kg of polyoxyethylene anhydrous sorbitan fatty acid ester, 35 kg of tripropylene glycol, and 258 kg of deionized water into a reaction kettle, heat to 50° C., stir until the solid is dissolved, and subject the dissolved liquid to high-pressure homogenization at 40 MPa to obtain a pre-emulsion, heat to 70° C., then add 800 g of azobisisobutylamidine dihydrochloride and 50 kg of deionized water, and keep the temperature for reaction for 7 hours to obtain a fluorine-containing emulsion.

[0057] Example 2

[0058] (1) Add 29 kg of toluene to a 50 L reactor equipped with a thermometer, condenser and stirring device, and heat to 105°C. Add a mixed solution of 7.5 kg of perfluorohexylethyl acrylate, 7.5 kg of vinylidene chloride, 7.5 kg of epoxy acrylate and 0.28 kg of benzoyl peroxide to the reactor, and control the addition to be completed within 4 hours. After the addition is completed, dissolve 20 g of benzoyl peroxide in 1 kg of toluene and add it dropwise to the reactor. Keep the temperature at 105°C for 4 hours, then cool to room temperature, then heat to 90°C, slowly drop 7.5 kg of acrylic acid and 0.1 kg of triphenylphosphine, raise the temperature to 95°C, keep the temperature for 4 hours, and obtain a vinylidene chloride oligomer solution with double bonds.

[0059] (3) The solution obtained in step (2) is subjected to reduced pressure distillation at 90° C. and 100 mmHg for 2 h to obtain a vinylidene chloride oligomer with a double bond.

[0060] (4) Weigh 43 kg of perfluorohexylethyl acrylate, 20 kg of octadecyl acrylate, 30 kg of benzyl methacrylate, 18 kg of the above-mentioned vinylidene chloride oligomer with double bonds, 8.6 kg of N-hydroxymethyl acrylamide, 1.3 kg of octadecyl trimethyl ammonium chloride, 2.13 kg of anhydrous sorbitan fatty acid ester, 2.13 kg of isomeric tridecyl alcohol polyoxyethylene ether, 2.13 kg of polyoxyethylene anhydrous sorbitan fatty acid ester, 35 kg of tripropylene glycol, and 258 kg of deionized water into a reaction kettle, heat to 50° C., stir until the solid is dissolved, homogenize the dissolved liquid at 40 MPa, heat to 70° C., then add 800 g of azobisisobutylamidine dihydrochloride and 50 kg of deionized water, and keep the temperature for reaction for 7 hours to obtain a fluorine-containing emulsion.

[0061] Example 3

[0062] (1) Add 29 kg of toluene to a 50 L reactor equipped with a thermometer, condenser and stirring device, and heat to 105°C. Add a mixed solution of 7 kg of perfluorohexylethyl acrylate, 7 kg of vinylidene chloride, 7 kg of epoxy acrylate and 0.28 kg of benzoyl peroxide to the reactor, and control the addition to be completed within 4 hours. After the addition is completed, dissolve 20 g of benzoyl peroxide in 1 kg of toluene and add it dropwise to the reactor. After keeping the temperature at 105°C for 4 hours, cool to room temperature, then heat to 90°C, slowly drop 7 kg of acrylic acid and 0.1 kg of triphenylphosphine, raise the temperature to 95°C, and keep the temperature for 4 hours to obtain a vinylidene chloride oligomer solution with double bonds.

[0063] (3) The liquid obtained in step (2) is subjected to reduced pressure distillation at 90° C. and 100 mmHg for 2 h to obtain a vinylidene chloride oligomer with a double bond.

[0064] (3) Weigh 43.5 kg of perfluorohexylethyl acrylate, 20 kg of octadecyl acrylate, 30 kg of benzyl methacrylate, 16 kg of the above-mentioned vinylidene chloride oligomer with double bonds, 8.6 kg of N-hydroxymethyl acrylamide, 1.3 kg of octadecyl trimethyl ammonium chloride, 2.13 kg of anhydrous sorbitan fatty acid ester, 2.13 kg of isomeric tridecyl alcohol polyoxyethylene ether, 2.13 kg of polyoxyethylene anhydrous sorbitan fatty acid ester, 35 kg of tripropylene glycol, and 258 kg of deionized water into a reaction kettle, heat to 50° C., stir until the solid is dissolved, homogenize the dissolved liquid at 40 MPa, heat to 70° C., then add 800 g of azobisisobutylamidine dihydrochloride and 50 kg of deionized water, and keep the temperature for reaction for 7 hours to obtain a fluorine-containing emulsion.

[0065] Example 4

[0066] (1) Add 29 kg of toluene to a 50 L reactor equipped with a thermometer, condenser and stirring device, and heat to 105°C. Add a mixed solution of 6.5 kg of perfluorohexylethyl acrylate, 6.5 kg of vinylidene chloride, 6.5 kg of epoxy acrylate and 0.28 kg of benzoyl peroxide to the reactor, and control the addition to be completed within 4 hours. After the addition is completed, dissolve 20 g of benzoyl peroxide in 1 kg of toluene and add it dropwise to the reactor. After keeping the temperature at 105°C for 4 hours, cool to room temperature, then heat to 90°C, slowly drop 6.5 kg of acrylic acid and 0.1 kg of triphenylphosphine, raise the temperature to 95°C, and keep the temperature for 4 hours to obtain a vinylidene chloride oligomer solution with double bonds.

[0067] (2) The liquid obtained in step (1) is subjected to reduced pressure distillation at 90° C. and 100 mmHg for 2 h to obtain a vinylidene chloride oligomer with a double bond.

[0068] (3) Weigh 44 kg of perfluorohexylethyl acrylate, 20 kg of octadecyl acrylate, 30 kg of benzyl methacrylate, 14 kg of the above-mentioned vinylidene chloride oligomer with double bonds, 8.6 kg of N-hydroxymethyl acrylamide, 1.3 kg of octadecyl trimethyl ammonium chloride, 2.13 kg of anhydrous sorbitan fatty acid ester, 2.13 kg of isomeric tridecyl alcohol polyoxyethylene ether, 2.13 kg of polyoxyethylene anhydrous sorbitan fatty acid ester, 35 kg of tripropylene glycol, and 258 kg of deionized water into a reaction kettle, heat to 50° C., stir until the solid is dissolved, homogenize the dissolved liquid at 40 MPa, heat to 70° C., then add 800 g of azobisisobutylamidine dihydrochloride and 50 kg of deionized water, and keep the temperature for reaction for 7 hours to obtain a fluorine-containing emulsion.

[0069] Example 5

[0070] (1) Add 29 kg of toluene to a 50 L reactor equipped with a thermometer, condenser and stirring device, and heat to 105°C. Add a mixture of 6 kg of perfluorohexylethyl acrylate, 6 kg of vinylidene chloride, 5.6 kg of epoxy acrylate and 0.28 kg of benzoyl peroxide to the reactor, and control the addition to be completed within 4 hours. After the addition is completed, dissolve 20 g of benzoyl peroxide in 1 kg of toluene and add it dropwise to the reactor. After keeping the temperature at 105°C for 4 hours, cool to room temperature, then heat to 90°C, slowly drop 5.6 kg of acrylic acid and 0.1 kg of triphenylphosphine, raise the temperature to 95°C, and keep the temperature for 4 hours to obtain a vinylidene chloride oligomer solution with double bonds.

[0071] (2) The solution obtained in step (1) is subjected to reduced pressure distillation at 90° C. and 100 mmHg for 2 h to obtain a vinylidene chloride oligomer with a double bond.

[0072] (3) Weigh 44.5 kg of perfluorohexylethyl acrylate, 20 kg of octadecyl acrylate, 30 kg of benzyl methacrylate, 12 kg of the above-mentioned vinylidene chloride oligomer with double bonds, 8.6 kg of N-hydroxymethyl acrylamide, 1.3 kg of octadecyl trimethyl ammonium chloride, 2.13 kg of anhydrous sorbitan fatty acid ester, 2.13 kg of isomeric tridecyl alcohol polyoxyethylene ether, 2.13 kg of polyoxyethylene anhydrous sorbitan fatty acid ester, 35 kg of tripropylene glycol, and 258 kg of deionized water into a reaction kettle, heat to 50° C., stir until the solid is dissolved, homogenize the dissolved liquid at 40 MPa, heat to 70° C., then add 800 g of azobisisobutylamidine dihydrochloride and 50 kg of deionized water, and keep the temperature for reaction for 7 hours to obtain a fluorine-containing emulsion.

[0073] Example 6

[0074] (1) Add 29 kg of toluene to a 50L reactor equipped with a thermometer, condenser and stirring device, and heat it to 105°C. Add a mixed solution of 5 kg of perfluorohexylethyl acrylate, 5 kg of vinylidene chloride, 5.6 kg of epoxy acrylate and 0.28 kg of benzoyl peroxide to the reactor, and control the addition to be completed within 4 hours. After the addition is completed, dissolve 20 g of benzoyl peroxide in 1 kg of toluene and add it dropwise to the reactor. Keep it at 105°C for 4 hours, then cool it to room temperature, then heat it to 90°C, slowly drop 5.6 kg of acrylic acid and 0.1 kg of triphenylphosphine, raise the temperature to 95°C, keep it at this temperature for 4 hours, and obtain a vinylidene chloride oligomer solution with double bonds.

[0075] (2) The solution obtained in step (1) is subjected to reduced pressure distillation at 90° C. and 100 mmHg for 2 h to obtain a vinylidene chloride oligomer with a double bond.

[0076] (3) Weigh 45.2 kg of perfluorohexylethyl acrylate, 20 kg of octadecyl acrylate, 30 kg of benzyl methacrylate, 10 kg of the above-mentioned vinylidene chloride oligomer with double bonds, 8.6 kg of N-hydroxymethyl acrylamide, 1.3 kg of octadecyl trimethyl ammonium chloride, 2.13 kg of anhydrous sorbitan fatty acid ester, 2.13 kg of isomeric tridecyl alcohol polyoxyethylene ether, 2.13 kg of polyoxyethylene anhydrous sorbitan fatty acid ester, 35 kg of tripropylene glycol, and 258 kg of deionized water into a reaction kettle, heat to 50° C., stir until the solid is dissolved, homogenize the dissolved liquid at 40 MPa, heat to 70° C., then add 800 g of azobisisobutylamidine dihydrochloride and 50 kg of deionized water, and keep the temperature for reaction for 7 hours to obtain a fluorine-containing emulsion.

[0077] Test data:

[0078] 1. Fabric processing and its properties

[0079] Fabric finishing process:

[0080] The fluorine-containing emulsions prepared in the comparative example and Examples 1-6 were diluted with deionized water to a fluorine-containing surface protective agent with a concentration of 10 g / L. The cotton cloth was immersed in the fluorine-containing surface protective agent for 20 minutes and rolled once with a padder to obtain a liquid carrying rate of 100%. After the two-immersion and two-rolling process, the cotton cloth was first baked at 80°C for 5 minutes and then baked at 170°C for 3 minutes.

[0081] The cotton cloth treated with the fluorine-containing surface protective agent was subjected to the following performance tests.

[0082] (1) Waterproofness test method

[0083] The spray water test is carried out according to AATCC-22. The water resistance grade is used to indicate the spray resistance. The suffix "+" attached to the data means that the performance is slightly better than the grade performance represented by the numerical value, and the suffix "-" means that the performance is slightly worse than the grade performance represented by the numerical value. The evaluation criteria are shown in Table 1.

[0084] Table 1 Waterproof performance evaluation standard

[0085]

[0086]

[0087] (2) Oil resistance performance test method

[0088] Carry out oil repellency test according to AATCC-TM118, drop oil of corresponding grade on fabric, observe the penetration within 30 seconds, the highest grade oil that cannot penetrate is the oil repellency grade of the waterproofing agent, the standard evaluation is shown in Table 2.

[0089] Table 2 Oil resistance performance evaluation standard

[0090] grade Evaluation Criteria 1 Medical lubricants 2 Mixed solution of 35 parts hexadecane and 65 parts medical lubricant 3 Hexadecane 4 Tetradecane 5 Dodecane 6 n-Decane 7 n-octane 8 n-Heptane

[0091] (3) Washing resistance test method

[0092] The washing powder is 2g / L, the bath ratio is 1:30, and the stirring speed is 150rpm. The fabric is placed in a constant temperature water bath at 40℃ and washed for 10 minutes, then washed with clean water for 2 minutes. After one wash, it is dried at 80℃ for 30 minutes and the waterproof and oil-proof grade is evaluated.

[0093] The test results are as follows:

[0094] Table 3 Waterproof and oilproof performance test results

[0095] serial number Waterproof grade Oil resistance grade Comparative Example 5 8 Example 1 4 5 Example 2 4+ 6 Example 3 4++ 7 Example 4 5 8 Example 5 5 8 Example 6 5 8

[0096] Table 4 Content of vinylidene chloride in fluorinated emulsion

[0097]

[0098]

[0099] Note: The content of vinylidene chloride is tested by gas chromatograph equipped with FID detector.

[0100] Table 5 Washing resistance of fluorinated surface protective agent after film formation

[0101] serial number Maintain waterproof level 4 or above for washing times Comparative Example 43 Example 1 66 Example 2 61 Example 3 57 Example 4 53 Example 5 45 Example 6 37

[0102] As shown in Tables 3-5, when the proportion of vinylidene chloride oligomer monomers with double bonds in Examples 1-6 decreases successively, the content of vinylidene chloride in the emulsion also decreases successively, the water-proof and oil-proof properties are improved, and the friction resistance is reduced. This is because: vinylidene chloride can improve the adhesion of the fluorine-containing surface protective agent, and when the amount of vinylidene chloride decreases, the friction resistance decreases. At the same time, due to the reduction in the amount of vinylidene chloride, the proportion of fluorine-containing functional groups with water-proof and oil-proof effects increases, thereby improving the water-proof and oil-proof properties.

[0103] Comparing Table 3 and Table 5, when the mass of the double-bonded vinylidene chloride oligomer accounts for 2.5-3% of the total mass of the reaction system (Examples 4 and 5), the emulsion has both excellent water and oil resistance and washability, and the residual vinylidene chloride content is low.

[0104] The present invention illustrates the implementation scheme of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a fluorine-containing emulsion, characterized in that: The following steps are involved: (1) adding a solvent, an initiator A, a vinylidene chloride monomer 1, a fluorinated acrylate monomer 2, and an epoxy acrylate monomer 3 into a reaction kettle, raising the temperature to perform solution polymerization, and after the polymerization is completed, adding acrylic acid and a catalyst to react to obtain a vinylidene chloride oligomer solution with double bonds; (2) distilling the above-mentioned vinylidene chloride oligomer solution with double bonds under reduced pressure to obtain vinylidene chloride oligomer with double bonds; (3) Add the above-mentioned vinylidene chloride oligomer with double bonds, fluorinated acrylate monomer 2, monomer 4, emulsifier, cosolvent, and deionized water into a reaction kettle, heat and stir to dissolve the solid, then homogenize under high pressure, increase the temperature, add initiator B, start emulsion polymerization, and obtain the fluorinated emulsion after the reaction is completed, wherein the monomer 4 at least contains N-hydroxymethyl acrylamide.

2. The preparation method according to claim 1, characterized in that: The fluorinated acrylate monomer 2 is perfluorohexylethyl acrylate; The monomer 4 is selected from at least one of octadecyl acrylate, benzyl methacrylate, and N-hydroxymethyl acrylamide, wherein the monomer 4 at least comprises N-hydroxymethyl acrylamide; The initiator A is selected from at least one of benzoyl peroxide, tert-butyl perbenzoate, and tert-butyl hydroperoxide; The initiator B is selected from at least one of azobisisobutylamidine dihydrochloride, azobisisobutylimidazoline hydrochloride, and ammonium persulfate; The emulsifier is at least one selected from octadecyl trimethyl ammonium chloride, sorbitan fatty acid ester, isomeric tridecanol polyoxyethylene ether, and polyoxyethylene sorbitan fatty acid ester.

3. The preparation method according to claim 1, characterized in that: The temperature of the solution polymerization in step (1) is 90-110°C.

4. The preparation method according to claim 1, characterized in that: The catalyst in step (1) is triphenylphosphine.

5. The preparation method according to claim 1, characterized in that: The specific conditions of the reduced pressure distillation in step (2) include: temperature 90-110° C., pressure 95-105 mmHg, and time 1-2 h.

6. The preparation method according to claim 1, characterized in that: In the step (3), the heating and stirring temperature is 35-50° C., and the pressure of the high-pressure homogenization is 30-45 MPa.

7. The preparation method according to claim 1, characterized in that: The cosolvent in step (3) is tripropylene glycol.

8. The preparation method according to claim 1, characterized in that: The temperature of the emulsion polymerization in step (3) is 65-75°C.

9. The preparation method according to claim 1, characterized in that: Taking the sum of the weight of each reaction monomer, initiator A, solvent, acrylic acid and catalyst in step (1) as 100 weight %, the proportion of each component is:

10. The preparation method according to claim 1, characterized in that: Taking the sum of the weight of each monomer, emulsifier, initiator B, co-solvent and deionized water in step (3) as 100 weight %, the proportion of each component is:

11. The preparation method according to claim 10, characterized in that: The proportion of the vinylidene chloride oligomer with double bonds is 2.5-3%.

12. A fluorine-containing surface protective agent, characterized in that: The invention comprises a fluorine-containing emulsion prepared by the preparation method according to any one of claims 1 to 11.

13. Use of the fluorine-containing surface protective agent according to claim 12 in fabric finishing.

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