Fluorine-containing chain extender for modifying polyurethane as well as preparation method and application of fluorine-containing chain extender

Abstract

The invention belongs to the technical field of macromolecules, and particularly relates to a fluorine-containing chain extender for modifying polyurethane as well as a preparation method and application of the fluorine-containing chain extender. The fluorine-containing chain extender for modifying polyurethane is diamine with a fluorine-containing side chain, and is prepared by the following steps: by taking fluoroether acyl fluoride, small-molecular alcohol and diethylenetriamine as reaction raw materials, firstly, carrying out esterification reaction on the fluoroether acyl fluoride and the small-molecular alcohol to obtain an intermediate fluoroether carboxylic ester; and carrying out amidation reaction on the intermediate fluoroether carboxylate and diethylenetriamine to obtain the fluorine-containing chain extender. The fluorine-containing chain extender has excellent reaction activity, the side chain fluorocarbon chain length of fluorine-containing polyurethane derived from the fluorine-containing chain extender is larger than or equal to 6, the polyurethane surface performance is greatly improved, and therefore the fluorine-containing chain extender has wide application prospects.

Description

Technical Field

[0001] This invention belongs to the technical field of polymers, specifically relating to a fluorinated chain extender for modified polyurethane, its preparation method, and its application. Background Technology

[0002] Polyurethane, with its unique and freely tunable soft and hard segment structure, has become a polymer with comprehensive applications in the field of synthetic polymer materials. Introducing fluorinated groups into the polyurethane structure, while retaining the basic characteristics of polyurethane, improves its surface properties, heat resistance, and overall properties, endowing it with excellent stain resistance, heat resistance, chemical corrosion resistance, and lubricity. Therefore, it has great application prospects in fields such as coating industry, leather decoration, textile finishing, and aerospace.

[0003] Polyurethanes possess highly modifiable structures; any fluorinated compound or polymer containing hydroxyl or amine groups can serve as a structural segment constituting a fluorinated polyurethane. Fluorinated polyurethanes can be classified into five main categories based on the location of the fluorinated segment introduction during their preparation: fluorocarbon-terminated fluorinated polyurethanes, hard-segment main-chain fluorinated polyurethanes, hard-segment side-chain fluorinated polyurethanes, soft-segment main-chain fluorinated polyurethanes, and soft-segment side-chain fluorinated polyurethanes. Among these, side-chain fluorinated polyurethanes are considered the most promising due to the migration effect of the fluorocarbon chain.

[0004] Fluorinated monomers with side chains are key to the preparation of fluorinated polyurethanes with side chains. These include fluorinated diisocyanates, fluorinated diols, and fluorinated diamines with side chains. Due to the extremely high technical threshold for the synthesis of fluorinated diisocyanates, there are virtually no reports on them.

[0005] Regarding fluorinated diamines with side chains, relevant reports { 《应用聚合物科学杂志》 ,2006, 102, 1863; 《高性能聚合物》 , 2013, 25, 894; 《应用》 《聚合物科学》 , 2005, 96, 2399; 《先进技术聚合物》 The substance, 2012, 23,877, is mainly prepared from fluorinated bisphenol compounds such as bisphenol AF and nitrochlorobenzene compounds through a two-step reaction of substitution and reduction. The fluorinated segment can be located in either the bisphenol compound or the nitrochlorobenzene compound. The existing side-chain fluorinated diamines generally have the following structural formula: , , It can be seen that the only fluorinated diamine with a side chain is trifluoromethyl.

[0006] The fluorinated polyurethanes prepared using the above-mentioned fluorinated diamines have short fluorocarbon chains, resulting in no significant improvement in surface properties and water contact angles generally below 90°C.

[0007] In summary, there is an urgent need to address the poor surface properties of side-chain fluorinated polyurethanes derived from side-chain fluorinated diamines. Summary of the Invention

[0008] The purpose of this invention is to address the aforementioned deficiencies by providing a fluorinated chain extender for modified polyurethane, its preparation method, and its applications. This fluorinated chain extender does not use perfluorooctanoic acid (PFOA) or its derivatives, making it safe and environmentally friendly. Furthermore, the fluorinated chain extender exhibits excellent reactivity, resulting in fluorinated polyurethanes with fluorocarbon chain lengths ≥6, and significantly improved surface properties, thus demonstrating broad application prospects.

[0009] The technical solution of this invention is as follows: A fluorinated chain extender for modifying polyurethane, which is a fluorinated diamine with a side chain, has the following specific structural formula: .

[0010] In the formula, R f ＇ for or m≥1, n≥2.

[0011] R f Selected from -OCF3, -OC2F5 or -OC3F7.

[0012] This fluorinated diamine with a side chain has three amino groups, one of which is an amide. The CN base of the amide is double-bonded, so it cannot react with isocyanates. The other two are a primary amine and a secondary amine, which are highly reactive with isocyanates. Therefore, this fluorinated diamine with a side chain is a bifunctional monomer and can be used as a chain extender in polyurethane synthesis.

[0013] A method for preparing a fluorinated chain extender for modified polyurethane, comprising using fluoroether fluoride, a small molecule alcohol and diethylenetriamine as reactants; firstly, fluoroether fluoride and a small molecule alcohol are reacted by esterification to obtain an intermediate fluoroether carboxylic acid ester; then, the intermediate fluoroether carboxylic acid ester is reacted by amidation with diethylenetriamine to obtain the fluorinated chain extender.

[0014] The fluoroether fluoride has any of the following structural formulas: or .

[0015] In the formula, R fSelected from -OCF3, -OC2F5 or -OC3F7; m≥1, n≥2.

[0016] The structural formula of the intermediate fluoroether carboxylic acid ester is shown below: .

[0017] In the formula, R f ＇ for or m≥1, n≥2.

[0018] R f Selected from -OCF3, -OC2F5 or -OC3F7.

[0019] R is selected from any one of -CH3, -CH2CH3, -CH2CH2CH3 or -CH(CH3)2.

[0020] The small molecule alcohol is selected from any one of methanol, ethanol, n-propanol or isopropanol.

[0021] The specific reaction process is as follows: .

[0022] Among them, R f ＇ for or m≥1, n≥2.

[0023] R f Selected from -OCF3, -OC2F5 or -OC3F7.

[0024] R is selected from any one of -CH3, -CH2CH3, -CH2CH2CH3 or -CH(CH3)2.

[0025] The fluorinated chain extender has a fluorocarbon chain with a more flexible and migrating fluoroether group, which is not a traditional perfluorocarbon structure and has a significant surface fluorine enrichment effect.

[0026] In this invention, the molar ratio of small molecule alcohol to fluoroether fluoride in the preparation method of the fluorinated chain extender for modified polyurethane is (1-10):1.

[0027] In this invention, the molar ratio of fluoroether carboxylate to diethylenetriamine in the preparation method of the fluorinated chain extender for modified polyurethane is 1:(2-5).

[0028] The preparation method of the fluorinated chain extender for modified polyurethane in this invention comprises the following specific steps: (1) First, fluoroether fluoride is added dropwise to a small molecule alcohol solution containing an acid-binding agent to carry out an esterification reaction, and crude fluoroether carboxylic acid ester is obtained.

[0029] Then, the crude fluoroether carboxylate was purified by distillation to obtain the intermediate fluoroether carboxylate. The crude fluoroether carboxylate was purified by two-stage distillation.

[0030] (2) First, the intermediate fluoroether carboxylic acid ester obtained in step (1) is added dropwise to a mixture of diethylenetriamine and solvent, and an amidation reaction is carried out in an inert gas atmosphere to obtain crude fluorinated diamine with side chain.

[0031] The obtained crude fluorinated diamine with side chains is then purified by distillation to obtain the fluorinated chain extender, and the diethylenetriamine and solvent are recovered. Distillation can be carried out using a thin-film evaporator, specifically a two-stage thin-film evaporator.

[0032] In this invention, the method for preparing the fluorinated chain extender for modified polyurethane, wherein the acid-binding agent in step (1) is selected from at least one of triethylamine, N,N-dimethyl-1,3-propanediamine, alkali metal carbonate, alkaline earth metal carbonate, alkali metal bicarbonate, or alkaline earth metal bicarbonate.

[0033] In the present invention, in the preparation method of the fluorinated chain extender for modified polyurethane, the molar ratio of acid binder to fluoroether fluoride in step (1) is 1-5:1.

[0034] In this invention, the preparation method of the fluorinated chain extender for modified polyurethane, in step (1), the reaction temperature of the esterification reaction is -20 to 50°C and the reaction time is 2-5 h.

[0035] In this invention, the preparation method of the fluorinated chain extender for modified polyurethane, in step (2), the reaction temperature of the amidation reaction is -20 to 10°C and the reaction time is 10-20 h.

[0036] In this invention, the solvent in step (2) of the method for preparing the fluorinated chain extender for modified polyurethane is selected from at least one of diethyl ether, tetrahydrofuran, methyl tert-butyl ether, ethylene glycol dimethyl ether, perfluoroisobutyl methyl ether, perfluoroisobutyl ethyl ether, tetrafluoroethyl trifluoroethyl ether, or tetrafluoroethyl tetrafluoropropyl ether.

[0037] An application of the above-mentioned fluorinated chain extender for modifying polyurethane in polyurethane modification, wherein the side chain fluorocarbon chain length of the fluorinated polyurethane derived using the fluorinated chain extender is ≥6.

[0038] In polyurethane modification, the chain extender used contains 5 mol%-7 mol% of the above-mentioned fluorinated chain extender.

[0039] The modified polyurethane has a water contact angle of 114-125°, a hard segment content of 30-32 wt%, and a fluorine content of 0.2-1.6 wt%.

[0040] The beneficial effects of this invention are as follows: 1. The fluorinated chain extender of the present invention has a fluorinated diamine side chain with a high fluorine content in its molecular structure and the fluorocarbon chain is located on the side chain with a fluorocarbon chain length ≥6. A small amount of this chain extender can effectively improve the surface properties of the synthesized fluorinated polyurethane.

[0041] 2. The fluorinated chain extender of the present invention has a fluorinated diamine side chain. The required fluorocarbon chain comes from fluoroether fluoride, which has no accumulation in the body and no potential carcinogenic or teratogenic effects on the body, making it an ideal substitute for traditional long C8 fluorocarbon chains.

[0042] 3. The fluorinated chain extender with fluorinated diamine side chain described in this invention uses inexpensive and readily available raw materials and is prepared through a two-step reaction of esterification and amidation. It has the characteristics of simple process, low safety risk, high reaction yield, good technical and economic efficiency, and easy to scale up. Attached Figure Description

[0043] Figure 1 The NMR fluorine spectrum of compound I, the fluorinated chain extender described in Examples 1-8.

[0044] Figure 2 The NMR fluorine spectrum of compound II, the fluorine-containing chain extender described in Example 9.

[0045] Figure 3 The NMR fluorine spectrum of compound III, the fluorine-containing chain extender described in Example 10.

[0046] Figure 4 The NMR fluorine spectrum of compound IV, the fluorine-containing chain extender described in Example 11.

[0047] Figure 5 The NMR fluorine spectrum of compound V, the fluorine-containing chain extender described in Example 12.

[0048] Figure 6 The image shows the 1H NMR spectrum of the fluorinated chain extender compound III.

[0049] Figure 7 The image shows the infrared spectrum of the fluorinated chain extender compound III. Detailed Implementation

[0050] The technical solution of the present invention will be described in detail below.

[0051] 1. Method for measuring contact angle: Refer to national standard GB / T 30693-2014 (Measurement of contact angle between plastic film and water).

[0052] 2. Calculation method for hard segment content in fluorinated polyurethane: the mass fraction of diisocyanate and chain extender in the total polyurethane.

[0053] 3. Calculation method for fluorine content in fluorinated polyurethane: Mass fraction of fluorinated chain extender in the total polyurethane × Mass fraction of fluorine atoms in the fluorinated chain extender.

[0054] Example 1 The fluorinated chain extender used for modifying polyurethane is a side-chain fluorinated diamine compound I with the following structural formula: .

[0055] The specific steps of the preparation method of the fluorinated chain extender for modified polyurethane are as follows: (1) In a dry three-necked reaction flask equipped with mechanical stirrer, temperature sensor and condenser, add 34.5g (0.75mol) ethanol and 75.9g (0.75mol) triethylamine in sequence, turn on the circulating cooling system and maintain the reaction system temperature at 50℃.

[0056] 67.2 g (0.15 mol) of fluoroether fluoride was added dropwise through a constant-pressure dropping funnel. Control the dropping rate to keep the reaction temperature at 50℃.

[0057] After the addition is complete, maintain a constant temperature of 50°C and stir for 5 hours; then slowly add 100 mL of pre-cooled saturated sodium bicarbonate solution to quench the reaction.

[0058] The organic phase was collected by separation, washed with water, dried with anhydrous sodium sulfate, and purified by distillation to obtain 57.7g of a colorless and transparent liquid, namely the intermediate fluoroether carboxylic acid ester.

[0059] Among them, the intermediate fluoroether carboxylate The yield was 81.2%, and the purity was ≥99%.

[0060] (2) Under nitrogen protection, add 30 mL of anhydrous tetrahydrofuran and 62.8 g (0.608 mol) of diethylenetriamine to a three-necked flask. Control the system temperature at 10 °C, and slowly add 57.7 g (0.12 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) through a constant pressure dropping funnel. After the addition is complete, maintain the reaction at 10 °C for 20 h, and then stop the reaction.

[0061] The majority of the unreacted diethylenetriamine and solvent were collected by vacuum distillation. The residue was dissolved in 50 mL of chloroform. The organic phase was washed with water, alkali, and brine. After drying with anhydrous sodium sulfate, the solvent was removed by rotary evaporation to obtain the crude product. Finally, 53.4 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 82.5%.

[0062] The reaction pathway described above is shown below: .

[0063] Example 2 The difference from Example 1 is that the reaction system temperature was maintained at 25°C in step (1). 57.25 g of the intermediate fluoroether carboxylic acid ester was obtained (yield 80.5%) with a purity ≥99%.

[0064] In step (2), the system temperature is controlled at 0°C, and 57.25g of the intermediate fluoroether carboxylic acid ester obtained in step (1) is added dropwise. After the addition is complete, the reaction temperature is maintained at 0°C for 20h, and then the reaction is stopped.

[0065] Finally, 53.57 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 83.5%.

[0066] Example 3 The difference from Example 1 is that the reaction system temperature was maintained at -20°C in step (1). 42.8 g of the intermediate fluoroether carboxylic acid ester was obtained (yield 60.2%) with a purity ≥99%.

[0067] In step (2), 30 mL of anhydrous tetrahydrofuran and 46.58 g (0.45 mol) of diethylenetriamine were added to the three-necked flask. The system temperature was controlled at -20 °C, and 42.8 g (0.09 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) was added dropwise. After the addition was completed, the reaction temperature was maintained at -20 °C for 20 h, and then the reaction was stopped.

[0068] Finally, 25.67 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 53.5%.

[0069] Example 4 The difference from Example 1 is that the reaction system temperature was maintained at 25°C in step (1). After the addition was complete, the reaction was stirred at a constant temperature of 25°C for 3 hours. 57.03 g of the intermediate fluoroether carboxylic acid ester was obtained (yield 80.2%) with a purity ≥99%.

[0070] In step (2), 30 mL of anhydrous tetrahydrofuran and 62.05 g (0.601 mol) of diethylenetriamine were added to the three-necked flask. The system temperature was controlled at 0 °C, and 57.03 g of the intermediate fluoroether carboxylic acid ester obtained in step (1) was added dropwise. After the addition was completed, the reaction temperature was maintained at 0 °C for 12 h, and then the reaction was stopped.

[0071] Finally, 53.56 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 83.8%.

[0072] Example 5 The difference from Example 1 is that the reaction system temperature was maintained at 25°C in step (1). After the addition was complete, the reaction was stirred at a constant temperature of 25°C for 1 hour. 49.9 g of the intermediate fluoroether carboxylic acid ester was obtained (yield 70.2%) with a purity ≥99%.

[0073] In step (2), 30 mL of anhydrous tetrahydrofuran and 54.3 g (0.526 mol) of diethylenetriamine were added to the three-necked flask. The system temperature was controlled at 0 °C, and 49.9 g (0.105 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) was added dropwise. After the addition was completed, the reaction temperature was maintained at 0 °C for 10 h, and then the reaction was stopped.

[0074] Finally, 39.6 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 70.8%.

[0075] Example 6 The difference from Example 1 is that in step (1), 13.82 g (0.3 mol) of ethanol and 22.76 g (0.23 mol) of triethylamine were added sequentially, and the reaction system temperature was maintained at 25°C. After the addition was complete, the reaction was stirred at a constant temperature of 25°C for 3 hours. 57.2 g of the intermediate fluoroether carboxylic acid ester was obtained (yield 80.5%) with a purity ≥99%.

[0076] In step (2), 30 mL of anhydrous tetrahydrofuran and 37.4 g (0.36 mol) of diethylenetriamine were added to the three-necked flask. The system temperature was controlled at 0 °C, and 57.25 g of the intermediate fluoroether carboxylic acid ester obtained in step (1) was added dropwise. After the addition was completed, the reaction temperature was maintained at 0 °C for 12 h, and then the reaction was stopped.

[0077] Finally, 53.1 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 82.8%.

[0078] Example 7 The difference from Example 1 is that in step (1), 6.91 g (0.15 mol) of ethanol and 22.76 g (0.225 mol) of triethylamine were added sequentially, and the reaction system temperature was maintained at 25°C. After the addition was complete, the reaction was stirred at a constant temperature of 25°C for 3 hours. 50.1 g of the intermediate fluoroether carboxylic acid ester was obtained (yield 70.5%) with a purity ≥99%.

[0079] In step (2), 30 mL of anhydrous tetrahydrofuran and 32.7 g (0.31 mol) of diethylenetriamine were added to the three-necked flask. The system temperature was controlled at 0 °C, and 50.13 g (0.105 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) was added dropwise. After the addition was completed, the reaction temperature was maintained at 0 °C for 12 h, and then the reaction was stopped.

[0080] Finally, 45.39 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 80.8%.

[0081] Example 8 The difference from Example 1 is that in step (1), 13.82 g (0.3 mol) of ethanol and 15.18 g (0.15 mol) of triethylamine were added sequentially, and the reaction system temperature was maintained at 25°C. After the addition was complete, the reaction was stirred at a constant temperature of 25°C for 3 hours. 46.58 g of the intermediate fluoroether carboxylic acid ester was obtained (yield 65.5%) with a purity ≥99%.

[0082] In step (2), 30 mL of anhydrous tetrahydrofuran and 30.4 g (0.29 mol) of diethylenetriamine were added to the three-necked flask. The system temperature was controlled at 0 °C, and 46.58 g (0.098 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) was added dropwise. After the addition was completed, the reaction temperature was maintained at 0 °C for 12 h, and then the reaction was stopped.

[0083] Finally, 42.17 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound I, with a yield of 80.8%.

[0084] Example 9 The fluorinated chain extender used for modifying polyurethane is a side-chain fluorinated diamine compound II with the following structural formula: [Structure formula shown below] .

[0085] The specific steps of the preparation method of the fluorinated chain extender for modified polyurethane are as follows: (1) In a dry three-necked reaction flask equipped with mechanical stirrer, temperature sensor and condenser, add 9.612 g (0.3 mol) methanol and 22.76 g (0.225 mol) triethylamine in sequence, turn on the circulating cooling system and maintain the reaction system temperature at 25 °C.

[0086] 59.705 g (0.15 mol) of fluoroether fluoride was added dropwise through a constant-pressure dropping funnel. Control the dropping rate to keep the reaction temperature at 25℃.

[0087] After the addition is complete, maintain a constant temperature of 25°C and stir for 3 hours; slowly add 100 mL of pre-cooled saturated sodium bicarbonate solution to quench the reaction.

[0088] The organic phase was collected by separation, washed with water, dried with anhydrous sodium sulfate, and purified by distillation to obtain 50.63 g of a colorless and transparent liquid, namely the intermediate fluoroether carboxylic acid ester.

[0089] Among them, the intermediate fluoroether carboxylate The yield was 82.3%, and the purity was ≥99%.

[0090] (2) Under nitrogen protection, add 30 mL of anhydrous tetrahydrofuran and 38.21 g (0.37 mol) of diethylenetriamine to a three-necked flask. Control the system temperature at 0 °C, and slowly add 50.63 g (0.12 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) through a constant pressure dropping funnel. After the addition is complete, maintain the reaction at 0 °C for 12 h, and then stop the reaction.

[0091] The majority of the unreacted diethylenetriamine and solvent were collected by vacuum distillation. The residue was dissolved in 50 mL of chloroform. The organic phase was washed with water, alkali, and brine. After drying with anhydrous sodium sulfate, the solvent was removed by rotary evaporation to obtain the crude product. Finally, 47.23 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound II, with a yield of 79.5%.

[0092] The reaction pathway described above is shown below: .

[0093] Example 10 The fluorinated chain extender used for modifying polyurethane is a side-chain fluorinated diamine compound III with the following structural formula: .

[0094] The specific steps of the preparation method of the fluorinated chain extender for modified polyurethane are as follows: (1) In a dry three-necked reaction flask equipped with mechanical stirrer, temperature sensor and condenser, add 9.6g (0.3mol) methanol and 22.76g (0.225mol) triethylamine in sequence, turn on the circulating cooling system and maintain the temperature of the reaction system at 25℃.

[0095] 74.7 g (0.15 mol) of fluoroether fluoride was added dropwise through a constant pressure dropping funnel. Control the dropping rate to keep the reaction temperature at 25℃.

[0096] After the addition is complete, maintain a constant temperature of 25°C and stir for 3 hours; slowly add 50 mL of pre-cooled saturated sodium bicarbonate solution to quench the reaction.

[0097] The organic phase was collected by separation, washed with water, dried with anhydrous sodium sulfate, and purified by distillation to obtain 59.95g of a colorless and transparent liquid, namely the intermediate fluoroether carboxylic acid ester.

[0098] Among them, the intermediate fluoroether carboxylate The yield was 78.3%, and the purity was ≥99%.

[0099] (2) Under nitrogen protection, add 30 mL of anhydrous tetrahydrofuran and 36.35 g (0.35 mol) of diethylenetriamine to a three-necked flask. Control the system temperature at 0 °C, and slowly add 59.95 g (0.12 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) through a constant pressure dropping funnel. After the addition is complete, maintain the reaction at 0 °C for 12 h, and then stop the reaction.

[0100] The majority of the unreacted diethylenetriamine and solvent were collected by vacuum distillation. The residue was dissolved in 50 mL of chloroform. The organic phase was washed with water, alkali, and brine. After drying with anhydrous sodium sulfate, the solvent was removed by rotary evaporation to obtain the crude product. Finally, 54.81 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound III, with a yield of 80.3%.

[0101] The reaction pathway described above is shown below: .

[0102] Example 11 The fluorinated chain extender used for modifying polyurethane is a side-chain fluorinated diamine compound IV with the following structural formula: [Structure formula shown below] .

[0103] The specific steps of the preparation method of the fluorinated chain extender for modified polyurethane are as follows: (1) In a dry three-necked reaction flask equipped with mechanical stirrer, temperature sensor and condenser, add 18.03 g (0.3 mol) of n-propanol and 22.76 g (0.225 mol) of triethylamine in sequence, turn on the circulating cooling system and maintain the reaction system temperature at 25 °C.

[0104] 47.106 g (0.15 mol) of fluoroether fluoride was added dropwise through a constant-pressure dropping funnel. Control the dropping rate to keep the reaction temperature at 25℃.

[0105] After the addition is complete, maintain a constant temperature of 25°C and stir for 3 hours; slowly add 100 mL of pre-cooled saturated sodium bicarbonate solution to quench the reaction.

[0106] The organic phase was collected by separation, washed with water, dried with anhydrous sodium sulfate, and purified by distillation to obtain a colorless and transparent liquid, namely the intermediate fluoroether carboxylic acid ester, 39.59 g.

[0107] Among them, the intermediate fluoroether carboxylate The yield was 75.3%, and the purity was ≥99%.

[0108] (2) Under nitrogen protection, add 30 mL of anhydrous tetrahydrofuran and 34.96 g (0.34 mol) of diethylenetriamine to a three-necked flask. Control the system temperature at 0 °C, and slowly add 39.59 g (0.11 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) through a constant pressure dropping funnel. After the addition is complete, maintain the reaction at 0 °C for 12 h, and then stop the reaction.

[0109] The majority of the unreacted diethylenetriamine and solvent were collected by vacuum distillation. The residue was dissolved in 50 mL of chloroform. The organic phase was washed with water, alkali, and brine. After drying with anhydrous sodium sulfate, the solvent was removed by rotary evaporation to obtain the crude product. Finally, 35.2 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound IV, with a yield of 78.3%.

[0110] The reaction pathway described above is shown below: .

[0111] Example 12 The fluorinated chain extender used for modifying polyurethane is a side-chain fluorinated diamine compound V with the following structural formula: [Structure formula shown below] .

[0112] The specific steps of the preparation method of the fluorinated chain extender for modified polyurethane are as follows: (1) In a dry three-necked reaction flask equipped with mechanical stirrer, temperature sensor and condenser, add 13.82 g (0.3 mol) of ethanol and 22.76 g (0.225 mol) of triethylamine in sequence, turn on the circulating cooling system and maintain the reaction system temperature at 25 °C.

[0113] 57 g (0.15 mol) of fluoroether fluoride was added dropwise through a constant pressure dropping funnel. Control the dropping rate to keep the reaction temperature at 25℃.

[0114] After the addition is complete, maintain a constant temperature of 25°C and stir for 3 hours; slowly add 100 mL of pre-cooled saturated sodium bicarbonate solution to quench the reaction.

[0115] The organic phase was collected by separation, washed with water, dried with anhydrous sodium sulfate, and purified by distillation to obtain 48.92 g of a colorless and transparent liquid, namely the intermediate fluoroether carboxylic acid ester.

[0116] Among them, the intermediate fluoroether carboxylate The yield was 80.3%, and the purity was ≥99%.

[0117] (2) Under nitrogen protection, add 30 mL of anhydrous tetrahydrofuran and 37.28 g (0.36 mol) of diethylenetriamine to a three-necked flask. Control the system temperature at 0 °C, and slowly add 48.92 g (0.12 mol) of the intermediate fluoroether carboxylic acid ester obtained in step (1) through a constant pressure dropping funnel. After the addition is complete, maintain the reaction at 0 °C for 12 h, and then stop the reaction.

[0118] The majority of the unreacted diethylenetriamine and solvent were collected by vacuum distillation. The residue was dissolved in 50 mL of chloroform. The organic phase was washed with water, alkali, and brine. After drying with anhydrous sodium sulfate, the solvent was removed by rotary evaporation to obtain the crude product. Finally, 44.36 g of colorless, transparent, viscous liquid was obtained by thin-film evaporation, which is the side-chain fluorinated diamine compound V, with a yield of 79.5%.

[0119] The reaction pathway described above is shown below: .

[0120] Example 13 Compound I (named FPUA), compound II (named FPUB), compound III (named FPUC), compound IV (named FPUD), and compound V (named FPUE) described in this invention were used as one of the chain extender components for the synthesis of fluorinated polyurethanes and compounded with 1,4-butanediol (BDO) to synthesize the various fluorinated polyurethanes shown in Table 1 according to the preparation steps described below.

[0121] In addition, using 1,4-butanediol (BDO) as a single chain extender as control group 1, the fluorinated polyurethanes shown in Table 1 were synthesized according to the same preparation steps described below.

[0122] The chain extender uses a fluorinated diamine with a side chain, which is a technology already in use. (named ref-1) [1] As control group 2, the fluorinated polyurethanes shown in Table 1 were synthesized in the same manner according to the preparation steps described below.

[0123] 500.10 g (0.5 mol) of dehydrated polytetrahydrofuran ether diol and 41.98 g (1.02 mol) of hexamethylene diisocyanate were added to a dry three-necked flask equipped with a mechanical stirrer. The mixture was heated to 60 °C and reacted under nitrogen protection for 4 h to obtain a polyurethane prepolymer.

[0124] The content of isocyanate groups (NCO) in the prepolymer was determined by titration using the di-n-butylamine method. After vacuum degassing, the prepolymer was sealed and stored in a desiccator.

[0125] Based on the measured isocyanate group content in the polyurethane prepolymer and the formulation of the fluorinated polyurethane (n(NCO):n(chain extender) = 2:1), the fluorinated chain extender is weighed and measured, wherein the chain extender is composed of 1,4-butanediol (BDO) and compounds I / II / III / IV / V. The specific formulation is shown in Table 1 below.

[0126] A fluorinated chain extender and 1,4-butanediol were mixed and dissolved in DMF to obtain a chain extender solution. This solution was slowly added dropwise to a polyurethane prepolymer at room temperature using a constant-pressure dropping funnel. After the addition was complete, the mixture was stirred for 1 hour. Then, 5‰ dibutyltin dilaurate was added as a catalyst, and the mixture was slowly heated to 60°C and reacted for 15 hours to obtain a fluorinated polyurethane DMF solution. The reacted solution was degassed and poured into a polytetrafluoroethylene mold, then dried in an oven at 100°C for 10 hours. The resulting fluorinated polyurethane film was demolded and subjected to contact angle analysis.

[0127] The synthetic route for the above-mentioned fluorinated polyurethane is shown below: .

[0128] Table 1 Performance indicators of various fluorinated polyurethane films

[0129] Note: [1]ref-1: 《先进技术聚合物》,2011年,23(5):877 - 883 .

[0130] As shown in Table 1, the surface properties of the synthesized polyurethane can be greatly improved by introducing a small amount of the fluorinated diamine described in this invention. Compared with traditional polyurethane, the water contact angle of the obtained fluorinated polyurethane is above 120°, showing excellent water repellency. In contrast, the water contact angle of traditional polyurethane is only 81.4°.

Claims

1. A fluorinated chain extender for modified polyurethane, characterized in that, This fluorinated chain extender is a fluorinated diamine with a side chain, and its structural formula is shown below: ； In the formula, R f ＇ for or m≥1, n≥2; R f Selected from -OCF3, -OC2F5 or -OC3F7.

2. A method for preparing a fluorinated chain extender for modified polyurethane as described in claim 1, characterized in that, The reaction raw materials are fluoroether fluoride, small molecule alcohol and diethylenetriamine; First, the intermediate fluoroether carboxylic acid ester is obtained by esterification reaction of fluoroether acyl fluoride with a small molecule alcohol; Then, the fluorinated chain extender is obtained by amidation reaction of the intermediate fluoroether carboxylic acid ester with diethylenetriamine; The fluoroether fluoride has any of the following structural formulas: or ; In the formula, R f Selected from -OCF3, -OC2F5 or -OC3F7; m≥1, n≥2; The structural formula of the intermediate fluoroether carboxylic acid ester is shown below: ； In the formula, R f ＇ for or m≥1, n≥2; R f Selected from -OCF3, -OC2F5 or -OC3F7; R is selected from any one of -CH3, -CH2CH3, -CH2CH2CH3 or -CH(CH3)2; The small molecule alcohol is selected from any one of methanol, ethanol, n-propanol or isopropanol.

3. The method for preparing the fluorinated chain extender for modified polyurethane according to claim 2, characterized in that, The molar ratio of the small molecule alcohol to fluoroether fluoride is (1-10):

1.

4. The method for preparing the fluorinated chain extender for modified polyurethane according to claim 2, characterized in that, The molar ratio of the intermediate fluoroether carboxylate to diethylenetriamine is 1:(2-5).

5. The method for preparing the fluorinated chain extender for modified polyurethane according to claim 2, characterized in that, The specific steps are as follows: (1) First, fluoroether fluoride is added dropwise to a small molecule alcohol solution containing an acid-binding agent to carry out an esterification reaction, and crude fluoroether carboxylic acid ester is obtained; Then, the crude fluoroether carboxylate was purified by distillation to obtain the intermediate fluoroether carboxylate. (2) First, the intermediate fluoroether carboxylic acid ester obtained in step (1) is added dropwise to a mixture of diethylenetriamine and solvent, and an amidation reaction is carried out in an inert gas atmosphere to obtain crude fluorinated diamine with side chain. Then, the obtained crude fluorinated diamine with side chain was purified by distillation to obtain the fluorinated chain extender, and the diethylenetriamine and solvent were recovered.

6. The method for preparing the fluorinated chain extender for modified polyurethane according to claim 5, characterized in that, The acid-binding agent in step (1) is selected from at least one of triethylamine, N,N-dimethyl-1,3-propanediamine, alkali metal carbonate, alkaline earth metal carbonate, alkali metal bicarbonate or alkaline earth metal bicarbonate. The solvent in step (2) is selected from at least one of diethyl ether, tetrahydrofuran, methyl tert-butyl ether, ethylene glycol dimethyl ether, perfluoroisobutyl methyl ether, perfluoroisobutyl ethyl ether, tetrafluoroethyl trifluoroethyl ether, or tetrafluoroethyl tetrafluoropropyl ether.

7. The method for preparing the fluorinated chain extender for modified polyurethane according to claim 5, characterized in that, In step (1), the molar ratio of acid-binding agent to fluoroether fluoride is (1-5):

1.

8. The method for preparing the fluorinated chain extender for modified polyurethane according to claim 5, characterized in that, The esterification reaction in step (1) is carried out at a temperature of -20 to 50°C for 2 to 5 hours.

9. The method for preparing a fluorinated chain extender for modified polyurethane according to claim 5, characterized in that, The reaction temperature of the amidation reaction in step (2) is -20 to 10°C, and the reaction time is 10 to 20 hours.

10. The application of the fluorinated chain extender for modifying polyurethane as described in claim 1 in polyurethane modification, characterized in that, The side chain fluorocarbon chain length of the fluorinated polyurethane derived using this fluorinated chain extender is ≥6. In polyurethane modification, the chain extender used contains 5 mol%-7 mol% of the fluorinated chain extender described in claim 1; The modified polyurethane has a hard segment content of 30-32 wt%, a fluorine content of 0.2-1.6 wt%, and a water contact angle of 114-125°.

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