Preparation method and application of fluoroalcohol-modified aqueous polyurethane emulsion

Abstract

A preparation method and application of a fluoroalcohol-modified waterborne polyurethane emulsion belongs to the technical field of polymer waterborne polyurethane. The present invention first uses diisocyanate and diol as base materials to synthesize a waterborne polyurethane prepolymer emulsion, then uses dihydric fluoroalcohol to extend the chain and modify the waterborne polyurethane prepolymer emulsion, and finally uses monohydric fluoroalcohol to carry out end-capping reaction and synergistic modification to obtain a monohydric fluoroalcohol and dihydric fluoroalcohol synergistically modified waterborne polyurethane emulsion. In the technical solution of the present invention, due to the surface aggregation of fluorine elements, the water resistance and salt spray resistance of the material are significantly improved, and the high bond energy of the carbon-fluorine bond significantly improves the thermal stability and mechanical properties of the material. The material prepared by the present invention has outstanding synergistic effects of monohydric fluoroalcohol and dihydric fluoroalcohol while ensuring good basic performance, and has good practical application value and industrial production prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of high molecular waterborne polyurethane, and particularly relates to a preparation method and application of a fluoroalcohol-modified waterborne polyurethane emulsion. Background Art

[0002] Currently, the performance of water-based polyurethane emulsions, which use water as a dispersion medium, cannot meet the application needs of various fields of society. Due to the introduction of hydrophilic groups, existing pure water-based polyurethane emulsions have low water resistance, poor salt spray resistance, poor mechanical properties, and poor thermal stability. This limits the wide range of applications of water-based polyurethane emulsions and restricts their application range. To make water-based polyurethane emulsions meet complex application scenarios, they need to be optimized and modified.

[0003] Existing technologies show slight improvements in thermal stability and tensile strength of waterborne polyurethanes modified with a single fluoroalcohol. However, their mechanical properties and water resistance remain low, hindering large-scale industrial application. Chinese patent publication number CN112250825A discloses an organic fluorine-modified waterborne polyurethane emulsion and its preparation method. This waterborne polyurethane emulsion, modified via a grafting reaction, exhibits only a slight improvement in tensile strength, while mechanical properties, water resistance, and thermal stability are poor, resulting in suboptimal overall performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a fluoroalcohol-modified waterborne polyurethane emulsion, by which the waterborne polyurethane is synergistically modified by chain extension with a divalent fluoroalcohol and end-capping with a monovalent fluoroalcohol, thereby significantly improving the water resistance, mechanical properties, salt spray resistance and thermal stability of the product while maintaining good basic performance of the product.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In one aspect, the present invention provides a method for preparing a fluoroalcohol-modified aqueous polyurethane emulsion, comprising the following steps:

[0007] (1) Under an inert atmosphere, diisocyanate, diol, and tin catalyst are mixed and heated and stirred to react to obtain a waterborne polyurethane prepolymer emulsion;

[0008] (2) adding a hydrophilic chain extender, a difluoroalcohol, and a polar organic solvent to the waterborne polyurethane prepolymer emulsion, heating and stirring the mixture to react, thereby obtaining a waterborne polyurethane prepolymer emulsion modified by a difluoroalcohol chain extender;

[0009] (3) Add a crosslinking agent, a conventional chain extender, and a monofluoroalcohol to the waterborne polyurethane prepolymer emulsion modified by the difluoroalcohol chain extender, heat and stir to react, and obtain a monofluoroalcohol and difluoroalcohol synergistically modified waterborne polyurethane prepolymer emulsion, then add an amine neutralizer, and finally add deionized water for emulsification and rotary evaporation to obtain a fluoroalcohol-modified waterborne polyurethane emulsion.

[0010] Preferably, in step (1), the diisocyanate is one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, aliphatic diisocyanate, xylene diisocyanate, or tetramethyl-m-xylene diisocyanate; the diol is one of polyethylene glycol, polypropylene glycol, polycaprolactone diol, or polybutylene adipate diol; and the tin catalyst is one of dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, or monobutyltin oxide.

[0011] Preferably, in step (1), the mass ratio of diol, diisocyanate and tin catalyst is 1:0.4-0.6:0.0001-0.0002.

[0012] Preferably, in step (1), the reaction temperature is 70-90°C and the reaction time is 2-4h.

[0013] Preferably, in step (2), the hydrophilic chain extender is one of 1,2-propylene glycol-3-sodium sulfonate or 1,4-butanediol-2-sodium sulfonate or dihydroxymethylpropionic acid or dihydroxymethylbutyric acid; the difluoroalcohol is one of perfluoroalkanediol or 2,2,3,3-tetrafluoro-1,4-butanediol or octafluoro-1,6-hexanediol or 4,4,4-trifluoro-3-(trifluoromethyl)-1,3-butanediol or 2,3,5,6-tetrafluoro-p-phenylenediol; and the polar organic solvent is one of methyl ethyl ketone or methyl formate or ethyl acetate or acetone or butyl acetate or dimethyl sulfoxide or tetrahydrofuran.

[0014] Preferably, in step (2), the mass ratio of the aqueous polyurethane prepolymer emulsion, the polar organic solvent, the hydrophilic chain extender, and the dihydric fluoroalcohol is 1:0.2-0.4:0.04-0.07:0.02-0.12.

[0015] Preferably, in step (2), the reaction temperature is 80-90° C. and the reaction time is 2-3 h.

[0016] Preferably, in step (3), the crosslinking agent is one of trimethylolpropane, propylene glycol, pentaerythritol, or isopentaerythritol; the conventional chain extender is one of ethylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, 1,3-propylene glycol, or 1,4-dihydroxymethylcyclohexane; the monofluoroalcohol is perfluorohexylethanol, perfluorooctylethanol, 3-perfluorooctylpropanol, octafluoropentanol, 3,3,4,4,5,5,5-heptafluoro-1-pentanol, perfluorodecanol, or pentafluoropropanol. one of them; the amine neutralizing agent is one of trimethylamine, triethylamine, triethanolamine or tributylamine; the mass ratio of the waterborne polyurethane prepolymer emulsion modified by the divalent fluoroalcohol chain extender, the crosslinking agent, the conventional chain extender, the monovalent fluoroalcohol, and the amine neutralizing agent is 1: 0.02-0.03: 0.025-0.035: 0.024-0.124: 0.03-0.05, and the mass ratio of the waterborne polyurethane prepolymer emulsion modified by the divalent fluoroalcohol chain extender and deionized water is 1: 1.2-1.8.

[0017] Preferably, in step (3), the heating reaction temperature is 40-90°C, the heating reaction time is 1.5-4h; the emulsification time is 5-60min, the emulsification speed is 7000-9000r / min; and the rotary evaporation temperature is 30-50°C.

[0018] On the other hand, the present invention provides an application of a fluoroalcohol-modified aqueous polyurethane emulsion prepared by the above preparation method, wherein the fluoroalcohol-modified aqueous polyurethane emulsion is used for an aqueous polyurethane coating.

[0019] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0020] 1. The technical solution of the present invention prepares a fluoroalcohol-modified aqueous polyurethane emulsion by synergistically modifying aqueous polyurethane through monofluoroalcohol end-capping and difluoroalcohol chain extension. The synergistically modified aqueous polyurethane emulsion has excellent basic performance. Compared with the aqueous polyurethane emulsion modified by a single fluoroalcohol in the prior art, the aqueous polyurethane emulsion synergistically modified by monofluoroalcohol and difluoroalcohol prepared by the present invention has a smaller particle size, moderate viscosity, higher solid content, and stronger emulsion stability. Its basic performance can meet the daily production needs in the field of aqueous polyurethane coatings, reflecting the good synergistic modification effect of monofluoroalcohol and difluoroalcohol on the basic performance of the modified aqueous polyurethane emulsion.

[0021] 2. The technical solution of the present invention synergistically modifies waterborne polyurethane through end-capping with monofluoroalcohol and chain extension with difluoroalcohol. Monofluoroalcohol is grafted to the main chain end of waterborne polyurethane as an end-capping modifier. Since the carbon-fluorine segment in the monofluoroalcohol has strong water repellency and the self-aggregation of the fluorine element, the synergistically modified waterborne polyurethane emulsion is made into a film. The fluorine element is directionally arranged on the surface of the film, and synergistically reduces the water absorption rate of the film with the difluoroalcohol. The water absorption rate within 24 hours is only 5.01%, and the water contact angle of the film is as high as 103.4°, which greatly improves the water resistance of the film.

[0022] 3. The technical solution of the present invention synergistically modifies waterborne polyurethane through monofluoroalcohol end-capping and difluoroalcohol chain extension. Since the fluorine-containing carbon chains are grafted onto the main chain of the waterborne polyurethane, the carbon-fluorine bonds between the chain ends and the chains are evenly distributed, which significantly improves the thermal stability and salt spray resistance of the waterborne polyurethane emulsion. It was made into a film and its performance was tested. It was found that the thermal decomposition temperature of the film was as high as 393.6°C, and the salt spray resistance was as long as 12 months.

[0023] 4. The technical solution of the present invention synergistically modifies waterborne polyurethane through end-capping with monofluoroalcohol and chain extension with difluoroalcohol. Difluoroalcohol is grafted onto the main chain of waterborne polyurethane as a chain extension modifier, which has the effect of improving the crosslinking degree of the system, reducing the amount of crosslinking agent used, reducing production costs, and being more environmentally friendly; the improvement of the crosslinking degree of the modified waterborne polyurethane and the higher carbon-fluorine bond energy synergistically improve the mechanical properties of the film. The tensile stress of the film is as high as 31.63MPa, the elongation at break is as high as 10.33, the wear resistance is good, the solid content is high, and it has good practical application value and industrial production prospects.

[0024] 5. In the prior art, the adhesion and pencil hardness of waterborne polyurethane modified with a single fluoroalcohol are almost the same as those of unmodified pure waterborne polyurethane, which is at a lower level. Compared with the prior art, the technical solution of the present invention uses a waterborne polyurethane emulsion modified with a monofluoroalcohol and a difluoroalcohol to prepare a film, and the adhesion and pencil hardness of the film are significantly improved. In particular, when the monofluoroalcohol content is 6wt% and the difluoroalcohol content is 8wt%, the film adhesion can reach a maximum of level 0 and the pencil hardness is as high as 5H, reflecting the excellent synergistic effect of the monofluoroalcohol and the difluoroalcohol. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a test chart of particle size and distribution of the modified waterborne polyurethane emulsion prepared in Example 1;

[0026] Figure 2 The water contact angle test diagram of the film prepared from the modified waterborne polyurethane emulsion prepared in Example 1 and each comparative example;

[0027] Figure 3This is a thermogravimetric test diagram of the film prepared from the modified waterborne polyurethane emulsion prepared in Example 1;

[0028] Figure 4 This is a salt spray test diagram of the film prepared from the modified waterborne polyurethane emulsion prepared in Example 1;

[0029] Figure 5 This is a tensile test diagram of the film prepared from the modified aqueous polyurethane emulsion prepared in Example 1. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Example 1

[0031] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of poly(1,4-butylene adipate) diol, 21.5 g of isophorone diisocyanate, and 0.0008 g of dibutyltin dilaurate were poured into the three-necked flask and stirred at 85 °C and 300 r / min for 3 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0032] (2) Add 3.5 g of dimethylol propionic acid and 5.65 g of 2,2,3,3-tetrafluoro-1,4-butanediol to the waterborne polyurethane prepolymer emulsion, and add 20 g of acetone to reduce the viscosity of the system. Continue stirring at 300 r / min and react at 85 ° C for 2.5 h to generate a waterborne polyurethane prepolymer emulsion modified by difluoroalcohol chain extension.

[0033] (3) 1.7 g of 1,4-butanediol, 1.3 g of trimethylolpropane and 4.58 g of 3-perfluorooctyl propanol were added to the emulsion obtained in the above step (2), and the mixture was stirred at 300 r / min and maintained at 85°C for 2 h to obtain a mono- and di-fluoroalcohol-synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was cooled to 45°C, and 2.5 g of triethylamine was added to the synergistically modified waterborne polyurethane prepolymer emulsion for neutralization reaction. The mixture was stirred at 150 r / min and maintained at 45°C for 1 h. 100 g of deionized water was added, and the mixture was emulsified at a speed of 8000 r / min for 15 min. The emulsion was then transferred to a single-necked flask, and acetone was removed by a rotary evaporator at 38°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 2

[0034] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of polyethylene glycol, 18.3 g of toluene diisocyanate, and 0.00053 g of dibutyltin oxide were poured into the three-necked flask and stirred at 200 r / min for 2 h at 70 ° C to react and generate a waterborne polyurethane prepolymer emulsion.

[0035] (2) Add 2.46 g of 1,2-propylene glycol-3-sulfonic acid sodium salt and 1.26 g of perfluoroalkane diol to the aqueous polyurethane prepolymer emulsion, and at the same time add 20 g of methyl ethyl ketone to reduce the viscosity of the system, continue stirring at 200 r / min, and react at 80°C for 2 h to generate a difluoroalcohol chain-extended modified aqueous polyurethane prepolymer emulsion;

[0036] (3) 1.52 g of ethylene glycol, 1.24 g of propylene glycol and 1.49 g of perfluorohexylethanol were added to the emulsion obtained in the above step (2), and the mixture was stirred at 200 r / min and maintained at 70°C for 1.5 h to obtain a mono- and di-fluoroalcohol synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was cooled to 40°C, and 1.83 g of trimethylamine was added to the synergistically modified waterborne polyurethane prepolymer emulsion for neutralization reaction. The mixture was stirred at 100 r / min and maintained at 40°C for 1 h. 73.6 g of deionized water was added, and the mixture was emulsified in an emulsifier at a speed of 7000 r / min for 5 min. The emulsion was then transferred to a single-necked flask and methyl ethyl ketone was removed by a rotary evaporator at 30°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 3

[0037] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of polypropylene glycol, 19.2 g of diphenylmethane diisocyanate, and 0.00059 g of dibutyltin diacetate were poured into the three-necked flask and stirred at 73 ° C and 230 r / min for 2.5 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0038] (2) Add 2.64 g of 1,4-butanediol-2-sulfonic acid sodium salt and 1.88 g of octafluoro-1,6-hexanediol to the aqueous polyurethane prepolymer emulsion, and at the same time add 20 g of methyl formate to reduce the viscosity of the system, continue stirring at 230 r / min, and react at 82 ° C for 2.5 h to generate a difluoroalcohol chain-extended modified aqueous polyurethane prepolymer emulsion;

[0039] (3) 1.58 g of diethylene glycol, 1.36 g of pentaerythritol and 2.1 g of perfluorooctylethanol were added to the emulsion obtained in the above step (2), and the mixture was stirred at 250 r / min. The reaction was maintained at 75°C for 2.5 h to obtain a mono- and di-fluoroalcohol synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was cooled to 43°C, and 2.01 g of triethanolamine was added to the synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was stirred at 120 r / min and the reaction was maintained at 43°C for 1 h. 79.8 g of deionized water was added, and the mixture was emulsified at a speed of 7500 r / min for 10 min. The emulsion was then transferred to a single-necked flask, and methyl formate was removed by a rotary evaporator at 35°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 4

[0040] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of polycaprolactone diol, 20.1 g of xylene diisocyanate, and 0.00064 g of monobutyltin oxide were poured into the three-necked flask and stirred at 250 r / min for 3.5 h at 76 ° C to react and generate a waterborne polyurethane prepolymer emulsion.

[0041] (2) Add 2.82 g of dihydroxymethylbutyric acid and 2.51 g of 4,4,4-trifluoro-3-(trifluoromethyl)-1,3-butanediol to the aqueous polyurethane prepolymer emulsion, and add 20 g of ethyl acetate to reduce the viscosity of the system. Continue stirring at 270 r / min and react at 84 ° C for 3 h to generate a difluoroalcohol chain-extended aqueous polyurethane prepolymer emulsion.

[0042] (3) 1.64 g of 1,6-hexanediol, 1.42 g of isopentaerythritol and 2.72 g of octafluoropentanol were added to the emulsion obtained in the above step (2), and the mixture was stirred at 320 r / min and maintained at 80°C for 3 h to obtain a mono- and di-fluoroalcohol synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was cooled to 47°C, 2.26 g of tributylamine was added to the synergistically modified waterborne polyurethane prepolymer emulsion, and the mixture was stirred at 140 r / min and maintained at 47°C for 1 h. 85.9 g of deionized water was added, and the mixture was emulsified at a speed of 8500 r / min for 30 min. The emulsion was then transferred to a single-necked flask, and ethyl acetate was removed by a rotary evaporator at 40°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 5

[0043] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of poly(1,4-butylene adipate diol), 22.9 g of tetramethyl-m-xylylene diisocyanate, and 0.00069 g of dibutyltin dilaurate were poured into the three-necked flask and stirred at 80 °C and 280 r / min for 4 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0044] (2) Add 3.07 g of dimethylol propionic acid and 3.77 g of 2,3,5,6-tetrafluorophenylenedimethanol to the aqueous polyurethane prepolymer emulsion, and add 20 g of butyl acetate to reduce the viscosity of the system. Continue stirring at 320 r / min and react at 86 ° C for 2 h to generate a difluoroalcohol chain-extended aqueous polyurethane prepolymer emulsion.

[0045] (3) 1.82 g of 1,3-propylene glycol, 1.55 g of trimethylolpropane, and 3.34 g of 3,3,4,4,5,5,5-heptafluoro-1-pentanol were added to the emulsion obtained in the above step (2), and the mixture was stirred at 350 r / min. The reaction was maintained at 90°C for 3.5 h to obtain a mono- and di-fluoroalcohol-synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was cooled to 50°C, and 2.38 g of triethylamine was added to the synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was stirred at 160 r / min and the reaction was maintained at 50°C for 1 h. 92 g of deionized water was added, and the mixture was emulsified in an emulsifier at a speed of 9000 r / min for 60 min. The emulsion was then transferred to a single-necked flask, and butyl acetate was removed by a rotary evaporator at 50°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 6

[0046] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of polyethylene glycol, 23.8 g of isophorone diisocyanate, and 0.00075 g of dibutyltin oxide were poured into the three-necked flask and stirred at 83 ° C and 330 r / min for 2 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0047] (2) Add 3.25 g of 1,2-propylene glycol-3-sulfonic acid sodium salt and 5.02 g of perfluoroalkane diol to the aqueous polyurethane prepolymer emulsion, and add 20 g of dimethyl sulfoxide to reduce the viscosity of the system. Continue stirring at 340 r / min and react at 87 ° C for 2.5 h to generate a difluoroalcohol chain-extended modified aqueous polyurethane prepolymer emulsion.

[0048] (3) To the emulsion obtained in the above step (2), 1.88 g of 1,4-dihydroxymethylcyclohexane, 1.61 g of propylene glycol and 3.96 g of perfluorodecanol were added, and the mixture was stirred at 200 r / min. After the reaction was maintained at 70°C for 1.5 h, a mono- and di-fluoroalcohol-synergistically modified waterborne polyurethane prepolymer emulsion was obtained. The mixture was cooled to 40°C, and 2.62 g of trimethylamine was added to the synergistically modified waterborne polyurethane prepolymer emulsion. The mixture was stirred at 100 r / min and the reaction was maintained at 40°C for 1 h. 98.2 g of deionized water was added, and the mixture was emulsified at a speed of 7000 r / min for 5 min. The emulsion was then transferred to a single-necked flask, and dimethyl sulfoxide was removed by a rotary evaporator at 30°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 7

[0049] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of polypropylene glycol, 24.7 g of toluene diisocyanate, and 0.00085 g of dibutyltin diacetate were poured into the three-necked flask and stirred at 87 ° C and 350 r / min for 2.5 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0050] (2) Add 3.68 g of 1,4-butanediol-2-sulfonic acid sodium salt and 6.28 g of octafluoro-1,6-hexanediol to the waterborne polyurethane prepolymer emulsion, and add 20 g of tetrahydrofuran to reduce the viscosity of the system. Continue stirring at 360 r / min and react at 88 ° C for 3 h to generate a waterborne polyurethane prepolymer emulsion modified by difluoroalcohol chain extension.

[0051] (3) 1.94 g of 1,4-butanediol, 1.67 g of pentaerythritol and 5.2 g of pentafluoropropanol were added to the emulsion obtained in the above step (2), stirred at 250 r / min, maintained at 75°C and continued to react for 2.5 h to obtain a mono- and di-fluoroalcohol synergistically modified waterborne polyurethane prepolymer emulsion, cooled to 43°C, 2.74 g of triethanolamine was added to the synergistically modified waterborne polyurethane prepolymer emulsion, stirred at 120 r / min, maintained at 43°C and reacted for 1 h, 101.2 g of deionized water was added, and the emulsifier was sheared and emulsified at a speed of 7500 r / min for 10 min, and then the emulsion was transferred to a single-necked flask, and tetrahydrofuran was removed by a rotary evaporator at 35°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 8

[0052] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of polycaprolactone diol, 26.1 g of diphenylmethane diisocyanate, and 0.00096 g of monobutyltin oxide were poured into the three-necked flask and stirred at 88 ° C and 380 r / min for 3 h to react to generate a waterborne polyurethane prepolymer emulsion;

[0053] (2) Add 3.99 g of dihydroxymethylbutyric acid and 6.91 g of 4,4,4-trifluoro-3-(trifluoromethyl)-1,3-butanediol to the waterborne polyurethane prepolymer emulsion, and add 20 g of acetone to reduce the viscosity of the system. Continue stirring at 380 r / min and react at 89 ° C for 2 h to generate a waterborne polyurethane prepolymer emulsion modified by difluoroalcohol chain extension.

[0054] (3) Add 2 g of 1,6-hexanediol, 1.8 g of isopentatriol, and 6.19 g of 3-perfluorooctyl propanol to the emulsion obtained in the above step (2), stir at 320 r / min, maintain 80°C and continue to react for 3 h to obtain a mono- and di-fluoroalcohol synergistically modified waterborne polyurethane prepolymer emulsion, cool to 47°C, add 2.93 g of tributylamine to the synergistically modified waterborne polyurethane prepolymer emulsion, stir at 140 r / min, maintain 47°C and react for 1 h, add 104.3 g of deionized water, and emulsify at an emulsifier speed of 8500 r / min for 30 min. Then transfer the emulsion to a single-necked flask, and remove acetone using a rotary evaporator at 40°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Example 9

[0055] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of poly(1,4-butylene adipate) diol, 27.4 g of xylene diisocyanate, and 0.00107 g of dibutyltin dilaurate were poured into the three-necked flask and stirred at 400 r / min for 3.5 h at 90 °C to generate a waterborne polyurethane prepolymer emulsion.

[0056] (2) Add 4.3 g of dimethylol propionic acid and 7.53 g of 2,3,5,6-tetrafluorophenylenedimethanol to the aqueous polyurethane prepolymer emulsion, and add 20 g of acetone to reduce the viscosity of the system. Continue stirring at 400 r / min and react at 90 ° C for 3 h to generate a difluoroalcohol chain-extended aqueous polyurethane prepolymer emulsion.

[0057] (3) Add 2.125 g of 1,3-propylene glycol, 1.86 g of trimethylolpropane, and 7.67 g of perfluorohexylethanol to the emulsion obtained in the above step (2), stir at 350 r / min, maintain 90°C and continue to react for 3.5 hours to obtain a mono- and di-fluoroalcohol-synergistically modified waterborne polyurethane prepolymer emulsion, cool to 50°C, add 3.05 g of triethylamine to the synergistically modified waterborne polyurethane prepolymer emulsion, stir at 160 r / min, maintain 50°C and react for 1 hour, add 110.4 g of deionized water, and emulsify at a shear speed of 9000 r / min in an emulsifier for 60 minutes. Then transfer the emulsion to a single-necked flask, and remove acetone using a rotary evaporator at 50°C to obtain a fluoroalcohol-modified waterborne polyurethane emulsion. Comparative Example 1

[0058] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of poly(1,4-butylene adipate) diol, 21.5 g of isophorone diisocyanate, and 0.0008 g of dibutyltin dilaurate were poured into the three-necked flask and stirred at 85 °C and 300 r / min for 3 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0059] (2) Add 3.5 g of dimethylol propionic acid to the aqueous polyurethane prepolymer emulsion, and at the same time add 20 g of acetone to reduce the viscosity of the system, continue stirring at 300 r / min, and react at 85 ° C for 2.5 h to generate an aqueous polyurethane prepolymer emulsion containing hydrophilic groups;

[0060] (3) 1.7 g of 1,4-butanediol and 1.3 g of trimethylolpropane were added to the above emulsion, stirred at 300 r / min, maintained at 85 °C for 2 h, then cooled to 45 °C, 2.5 g of amine neutralizer triethylamine was added, stirred at 150 r / min, maintained at 45 °C for 1 h, 100 g of deionized water was added, and the emulsifier was sheared and emulsified at a speed of 8000 r / min for 15 min. The emulsion was then transferred to a single-necked flask, and acetone was removed using a rotary evaporator at 38 °C to obtain a pure aqueous polyurethane emulsion. Comparative Example 2

[0061] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of poly(1,4-butylene adipate) diol, 21.5 g of isophorone diisocyanate, and 0.0008 g of dibutyltin dilaurate were poured into the three-necked flask and stirred at 85 °C and 300 r / min for 3 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0062] (2) Add 3.5 g of dimethylol propionic acid to the aqueous polyurethane prepolymer emulsion, and at the same time add 20 g of acetone to reduce the viscosity of the system, continue stirring at 300 r / min, and react at 85 ° C for 2.5 h to generate an aqueous polyurethane prepolymer emulsion containing hydrophilic groups;

[0063] (3) 1.7 g of 1,4-butanediol, 1.3 g of trimethylolpropane, and 4.58 g of 3-perfluorooctyl propanol were added to the above emulsion, stirred at 300 r / min, and the reaction was maintained at 85°C for 2 h to obtain a monofluoroalcohol-terminated modified waterborne polyurethane prepolymer emulsion. The temperature was lowered to 45°C, and 2.5 g of an amine neutralizer, triethylamine, was added to the monofluoroalcohol-terminated modified waterborne polyurethane prepolymer emulsion. The mixture was stirred at 150 r / min and the reaction was maintained at 45°C for 1 h. 100 g of deionized water was added, and the emulsifier was sheared and emulsified at a speed of 8000 r / min for 15 min. The emulsion was then transferred to a single-necked flask, and acetone was removed using a rotary evaporator at 38°C to obtain a monofluoroalcohol-terminated modified waterborne polyurethane emulsion. Comparative Example 3

[0064] (1) Nitrogen was introduced into the three-necked flask in advance to keep the reaction path filled with inert gas and remove interfering impurities such as air and moisture in the device. 40 g of poly(1,4-butylene adipate) diol, 21.5 g of isophorone diisocyanate, and 0.0008 g of dibutyltin dilaurate were poured into the three-necked flask and stirred at 85 °C and 300 r / min for 3 h to react and generate a waterborne polyurethane prepolymer emulsion.

[0065] (2) Add 3.5 g of dimethylol propionic acid and 5.65 g of 2,2,3,3-tetrafluoro-1,4-butanediol to the waterborne polyurethane prepolymer emulsion, and add 20 g of acetone to reduce the viscosity of the system. Continue stirring at 300 r / min and react at 85 ° C for 2.5 h to generate a difluoroalcohol chain-extended modified waterborne polyurethane prepolymer emulsion.

[0066] (3) 1.7 g of 1,4-butanediol and 1.3 g of trimethylolpropane were added to the above emulsion, stirred at 300 r / min, maintained at 85 °C for 2 h, then cooled to 45 °C, 2.5 g of amine neutralizer triethylamine was added, stirred at 150 r / min, maintained at 45 °C for 1 h, 100 g of deionized water was added, and the emulsifier was sheared and emulsified at a speed of 8000 r / min for 15 min. The emulsion was then transferred to a single-necked flask, and acetone was removed using a rotary evaporator at 38 °C to obtain a difluoroalcohol chain-extended modified waterborne polyurethane emulsion.

[0067] Test Example 1

[0068] The particle size and distribution of the sample emulsions in the examples and comparative examples were measured using a NanoZS nanoparticle size potentiometer manufactured by Malvern. The viscosity of the sample emulsions was measured using an NDJ-5S digital rotational viscometer with a 31# rotor. The test results were based on the standard GB / T7198-1987. In the stability test, 5 mL of the emulsion was weighed and placed in a test tube. The centrifuge speed was set to 3000 r / min and the sample was centrifuged for 20 min. If the sample did not delaminate or precipitate, it indicated that the sample emulsion had good stability.

[0069]

[0070] Table 1 shows the performance test of the sample emulsions. The basic performance of the sample emulsion of Example 1 is excellent, the performance of the sample emulsions of other examples is good, and the performance of the sample emulsions of the comparative example is poor. Figure 1 The particle size and distribution test diagram of the modified aqueous polyurethane emulsion prepared in Example 1 is shown in combination with the above table. Compared with the comparative example in which the aqueous polyurethane emulsion is modified with a single fluoroalcohol, the aqueous polyurethane emulsion in the embodiment is synergistically modified with a monofluoroalcohol and a difluoroalcohol. The sample particle size is smaller (72.8-81.9 nm), the viscosity is moderate (108.8-128.2 mPa·s), the solid content is higher (26.6%-29.8%), the emulsion is more stable, and its basic performance can meet the daily production requirements of the national aqueous polyurethane coating field, reflecting the good synergistic modification effect of the monofluoroalcohol and the difluoroalcohol on the basic performance of the emulsion.

[0071] Test Example 2

[0072] The examples and comparative samples were subjected to film-forming treatment. A polytetrafluoroethylene mold with a specification of 15×8×2 (cm) was cleaned with ethanol, placed in an oven for drying, and then taken out. An appropriate amount of emulsion was poured into the mold groove, and the mold was placed horizontally to make its surface flat and uniform without bubbles. After being dried in a dark environment at 25°C for three days, it was placed in a 45°C oven for drying for 24 hours. After the water was completely evaporated, it was taken out to obtain a film.

[0073] The water contact angle of the sample films of the embodiment and the comparative example was tested by the sessile drop method, and their water resistance was characterized using a DSA100S video contact angle meter; a salt spray test was performed in accordance with the national standard QC / T484-1999 "Paint Coating Industry Standard of the People's Republic of China", and the salt spray was a 5wt% sodium chloride solution; a thermal stability test was performed using a TGA thermogravimetric analyzer, with the heating rate set at 15°C / min and the heating range set at 25-550°C.

[0074]

[0075] Table 2 shows the water resistance, heat resistance and salt spray resistance test of the sample film. Figure 2The water contact angle test diagrams of the films prepared from the modified water-based polyurethane emulsions prepared in Example 1 and the comparative examples show that the water resistance of the sample films of the examples is significantly improved. Compared with the comparative examples, the water contact angles of the example films are excellent. Due to the water repellency of the carbon fluorine chain segments and the self-aggregation of the fluorine element, they are oriented on the surface of the film. The water contact angle of the example films can reach up to 103.4°, and the lowest water absorption rate is only 5.01%, indicating that the introduction of monofluoroalcohol and difluoroalcohol greatly improves the water resistance of the film, and the surface aggregation of the fluorine element greatly improves the problem of poor water resistance of the film, and the synergistic effect is outstanding.

[0076] Figure 3 The thermogravimetric test diagram of the film prepared from the modified waterborne polyurethane emulsion prepared in Example 1 shows that due to the high CF bond energy, the fluorinated carbon chains are grafted onto the main chain of the waterborne polyurethane, and the CF bonds between the chain ends and the chains are evenly distributed. The thermal decomposition temperature of the film of the example is increased. When the film is thermally decomposed by 10%, the decomposition temperature is 312.3°C. When the film is thermally decomposed by 50%, the decomposition temperature is 393.6°C. Compared with the comparative example, there is a significant increase, which proves the good synergistic effect of the mono- and di-fluoroalcohols. Figure 4 This is a salt spray test image of the film prepared with the modified waterborne polyurethane emulsion prepared in Example 1. No obvious rust appeared at the intersection of the film within 12 months, indicating that its salt spray resistance is excellent, which is significantly improved compared with the single fluoroalcohol modified waterborne polyurethane.

[0077] Test Example 3

[0078] The film adhesion of the samples of the examples and comparative examples was tested according to the GB-T9286-1998 test standard, which is graded from 0 to 5, with grade 0 being the best and grade 5 being the worst. The pencil hardness was tested according to the GB-T6739-2006 test standard using a pencil hardness tester. The pencil hardness test scale ranges from 9B to 9H from soft to hard. The pencil hardness test scale described below includes HB, H, 2H, 3H, 4H, and 5H, with grade 5H being the best and grade HB being the worst. The mechanical properties, including tensile stress and strain, were tested using a 3344 electronic universal material testing machine. The wear resistance was tested according to the GB / T23988-2009 test standard.

[0079]

[0080] Table 3 is the test data of the mechanical properties of the film. Figure 5The tensile test diagram of the film prepared from the modified water-based polyurethane emulsion prepared in Example 1 shows that compared with the comparative example, the increase in cross-linking degree and the higher CF bond energy synergistically improve the mechanical properties of the synergistically modified water-based polyurethane film. The tensile stress of the water-based polyurethane film synergistically modified by the mono- and di-fluoroalcohols can reach up to 31.63 MPa, the elongation at break can reach up to 10.33, and the minimum wear resistance is only 3.1 mg, with significant improvement in mechanical properties. In particular, when a single fluoroalcohol is used to modify the water-based polyurethane, its adhesion and pencil hardness are almost the same as those of the unmodified pure water-based polyurethane, and are at a lower level. After the mono- and di-fluoroalcohols are introduced to synergistically modify the water-based polyurethane emulsion, the synergistic effect causes the modified water-based polyurethane film to have a maximum adhesion of level 0 and a maximum pencil hardness of 5H, achieving significant improvement, reflecting the excellent synergistic effect of the mono- and di-fluoroalcohols, which is an effect that cannot be achieved by using a single fluoroalcohol to modify the water-based polyurethane emulsion, and the synergistic effect of the two is outstanding.

[0081] The above-described specific embodiments further illustrate the present invention in detail, but these descriptions should not be construed as limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a fluoroalcohol-modified aqueous polyurethane emulsion, characterized in that: The steps include: (1) Under an inert atmosphere, diisocyanate, diol, and tin catalyst are mixed and heated with stirring to react to obtain a waterborne polyurethane prepolymer emulsion; wherein the mass ratio of diol, diisocyanate, and tin catalyst is 1:0.4-0.6:0.0001-0.0002; (2) Adding a hydrophilic chain extender, a difluoroalcohol, and a polar organic solvent to an aqueous polyurethane prepolymer emulsion, heating and stirring the mixture to react, and obtaining an aqueous polyurethane prepolymer emulsion modified by a difluoroalcohol chain extender; wherein the mass ratio of the aqueous polyurethane prepolymer emulsion, the polar organic solvent, the hydrophilic chain extender, and the difluoroalcohol is 1:0.2-0.4:0.04-0.07:0.02-0.12; and the difluoroalcohol is one of perfluoroalkanediol, 2,2,3,3-tetrafluoro-1,4-butanediol, octafluoro-1,6-hexanediol, 4,4,4-trifluoro-3-(trifluoromethyl)-1,3-butanediol, and 2,3,5,6-tetrafluoro-p-phenylenediol; (3) Add a crosslinking agent, a conventional chain extender, and a monofluoroalcohol to the aqueous polyurethane emulsion modified by the difluoroalcohol chain extender, heat and stir to react, and obtain an aqueous polyurethane prepolymer emulsion modified by the monofluoroalcohol and the difluoroalcohol, then add an amine neutralizer, and finally add deionized water for emulsification and rotary evaporation to obtain a fluoroalcohol-modified aqueous polyurethane emulsion; wherein the mass ratio of the aqueous polyurethane emulsion modified by the difluoroalcohol chain extender, the crosslinking agent, the conventional chain extender, the monofluoroalcohol, and the amine neutralizer is 1:0.02-0.03:0.025-0.035 :0.024-0.124:0.03-0.05; the cross-linking agent is one of trimethylolpropane, glycerol, pentaerythritol or isopentaerythritol; the conventional chain extender is one of ethylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, 1,3-propylene glycol or 1,4-dihydroxymethylcyclohexane; the monofluoroalcohol is one of perfluorohexylethanol, perfluorooctylethanol, 3-perfluorooctylpropanol, octafluoropentanol, 3,3,4,4,5,5,5-heptafluoro-1-pentanol, perfluorodecanol or pentafluoropropanol.

2. The method for preparing the fluoroalcohol-modified aqueous polyurethane emulsion according to claim 1, wherein In the step (1), the diisocyanate is one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, aliphatic diisocyanate, xylene diisocyanate, or tetramethyl-m-xylene diisocyanate; the diol is one of polyethylene glycol, polypropylene glycol, polycaprolactone diol, or polybutylene adipate diol; and the tin catalyst is one of dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, or monobutyltin oxide.

3. The method for preparing the fluoroalcohol-modified aqueous polyurethane emulsion according to claim 1, wherein In the step (1), the reaction temperature is 70-90°C and the reaction time is 2-4 hours.

4. The method for preparing the fluoroalcohol-modified aqueous polyurethane emulsion according to claim 1, wherein In the step (2), the hydrophilic chain extender is one of 1,2-propylene glycol-3-sodium sulfonate, 1,4-butanediol-2-sodium sulfonate, dihydroxymethylpropionic acid, or dihydroxymethylbutyric acid; and the polar organic solvent is one of methyl ethyl ketone, methyl formate, ethyl acetate, acetone, butyl acetate, dimethyl sulfoxide, or tetrahydrofuran.

5. The method for preparing the fluoroalcohol-modified aqueous polyurethane emulsion according to claim 1, wherein In the step (2), the reaction temperature is 80-90°C and the reaction time is 2-3h.

6. The method for preparing the fluoroalcohol-modified aqueous polyurethane emulsion according to claim 1, wherein In the step (3), the amine neutralizing agent is one of trimethylamine, triethylamine, triethanolamine, and tributylamine; and the mass ratio of the divalent fluoroalcohol chain-extended modified aqueous polyurethane emulsion to deionized water is 1:1.2-1.

8.

7. The method for preparing the fluoroalcohol-modified aqueous polyurethane emulsion according to claim 1, wherein In the step (3), the heating reaction temperature is 40-90°C, the heating reaction time is 1.5-4h; the emulsification time is 5-60min, the emulsification speed is 7000-9000r / min; and the rotary evaporation temperature is 30-50°C.

8. An application of a fluoroalcohol-modified aqueous polyurethane emulsion prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The fluoroalcohol-modified aqueous polyurethane emulsion is applied to an aqueous polyurethane coating.

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