A kind of aminosulfonate chain extender and its preparation method and application, and preparation method of waterborne polyurethane

Abstract

The invention provides an aminosulfonate chain extender and a preparation method and application thereof, and a preparation method of waterborne polyurethane, and relates to the technical field of waterborne polyurethane synthesis. The aminosulfonate chain extender provided by the invention can be used to prepare waterborne polyurethane with high solid content, and the preparation cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of waterborne polyurethane synthesis, and in particular to an aminosulfonate chain extender, a preparation method and application thereof, and a preparation method of waterborne polyurethane. Background Art

[0002] Waterborne polyurethane has a wide range of applications in coatings, inks, textiles, leather, adhesives and other industries. At present, a major preparation method for waterborne polyurethane is to introduce hydrophilic groups, such as carboxyl groups, tertiary amine groups, or oligo(poly)ethylene glycol segments, into polyurethane prepolymers containing isocyanate end groups, and then quickly disperse the polyurethane prepolymers in water, add an amine-containing chain extender for chain extension, and obtain anionic, cationic and nonionic waterborne polyurethanes.

[0003] Commonly used chain extenders containing amine groups include ethylenediamine, propylenediamine, butylene diamine, hexamethylenediamine, isophorone diamine, sodium ethylenediamine sulfonate (A95), etc. Among them, sodium ethylenediamine sulfonate (A95) is a chain extender that can be used to prepare high-solid waterborne polyurethane. By introducing sulfonic acid groups into the polyurethane molecular chain through the chain extender, the stability of the polyurethane molecular chain can be greatly improved, and the performance of the waterborne polyurethane can be improved. At present, there are only a few commercial products such as sodium ethylenediamine sulfonate for sulfonate chain extenders, which are expensive. Therefore, it is of great significance to develop new amine sulfonate chain extenders. Summary of the invention

[0004] The purpose of the present invention is to provide an aminosulfonate chain extender and a preparation method and application thereof, and a method for preparing waterborne polyurethane. The aminosulfonate chain extender provided by the present invention can be used to prepare waterborne polyurethane with high solid content and has low preparation cost.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an aminosulfonate chain extender having a structure shown in Formula I:

[0007] H2N-R1-NH-CH2-CH2-R-SO3R3 Formula I;

[0008] In the formula I, R includes or methylene;

[0009] In the formula I, R1 is an alkylene group, a cycloalkylene group or an aralkylene group; R3 is H, Na or K;

[0010] In the above R, R2 is an alkylene group; R4 is an alkylene group.

[0011] Preferably, the alkylene group in R1 is an alkylene group having 1 to 6 carbon atoms; the cycloalkylene group in R1 is a cycloalkylene group having 5 to 10 carbon atoms; and the aralkylene group in R1 is an aralkylene group having 6 to 10 carbon atoms.

[0012] Preferably, the alkylene group in R2 is an alkylene group having 1 to 6 carbon atoms; and the alkylene group in R4 is an alkylene group having 1 to 6 carbon atoms.

[0013] The present invention provides a method for preparing the aminosulfonate chain extender described in the above technical scheme, comprising the following steps:

[0014] The diamine, the sulfonic acid substituted propylene derivative, water and the polymerization inhibitor are mixed to carry out an addition reaction to obtain an aqueous solution of an aminosulfonate chain extender;

[0015] The structural formula of the sulfonic acid substituted propylene derivative is H2C=CH-R-SO3R3;

[0016] The structural formula of the diamine is NH2-R1-NH2.

[0017] Preferably, the sulfonic acid substituted propylene derivative includes one or more of 3-sulfopropyl acrylate, 2-acrylic acid-2-methanesulfonate, acrylic acid-2-alkylsulfonate, acrylic acid-2-alkylsulfonate, 2-propylene-1-sulfonic acid, 2-propylene-1-sulfonate, 2-acrylamide-2-methylpropanesulfonic acid and 2-acrylamide-2-methylpropanesulfonate.

[0018] Preferably, the molar ratio of the sulfonic acid substituted propylene derivative to the diamine is 1:1 to 1.1.

[0019] Preferably, the addition reaction comprises a first addition reaction and a second addition reaction carried out sequentially; the temperature of the first addition reaction is 5 to 30° C.; the time of the first addition reaction is 2 to 4 hours; the temperature of the second addition reaction is 50 to 60° C.; the time of the second addition reaction is 2 to 5 hours.

[0020] The present invention provides the use of the sulfonate amino acid chain extender described in the above technical solution and prepared by the preparation method described in the above technical solution in the preparation of waterborne polyurethane.

[0021] The present invention provides a method for preparing waterborne polyurethane, comprising the following steps:

[0022] A chain extender and an aqueous polyurethane prepolymer containing isocyanate terminal groups are mixed to carry out a chain extension reaction to obtain an aqueous polyurethane; the chain extender is the aminosulfonate chain extender described in the above technical solution or the aminosulfonate chain extender prepared by the preparation method described in the above technical solution.

[0023] Preferably, the molar ratio of the primary amine group in the aminosulfonate chain extender to the isocyanate terminal group in the waterborne polyurethane prepolymer is 0.3 to 0.5:1.

[0024] The invention provides an aminosulfonate chain extender. Since the reaction activities of the amino group and isocyanate of the chain extender are different, the aminosulfonate chain extender provided by the invention can be used to prepare waterborne polyurethane with high solid content. DETAILED DESCRIPTION

[0025] The present invention provides an aminosulfonate chain extender having a structure shown in Formula I:

[0026] H2N-R1-NH-CH2-CH2-R-SO3R3 Formula I;

[0027] In the formula I, R includes or methylene;

[0028] In the formula I, R1 is an alkylene group, a cycloalkylene group or an aralkylene group; R3 is H, Na or K;

[0029] In the above R, R2 is an alkylene group; R4 is an alkylene group.

[0030] In the present invention, the aminosulfonate chain extender preferably has a structure shown in any one of formulas (1) to (3):

[0031]

[0032] H2N-R1-NH-CH2-CH2-CH2-SO3R3 (3).

[0033] In the present invention, the alkylene group in R1 is an alkylene group with 1 to 6 carbon atoms; the cycloalkylene group in R1 is a cycloalkylene group with 5 to 10 carbon atoms; the aralkylene group in R1 is an aralkylene group with 6 to 10 carbon atoms. In a specific embodiment of the present invention, R1 is ethylene or n-butylene.

[0034] In the present invention, the alkylene group in R2 is an alkylene group having 1 to 6 carbon atoms. In a specific embodiment of the present invention, R2 is a tert-butyl group. In the present invention, the alkylene group in R4 is an alkylene group having 1 to 6 carbon atoms. In a specific embodiment of the present invention, R4 is a propylene group.

[0035] In a specific embodiment of the present invention, the aminosulfonate chain extender comprises:

[0036]

[0037]

[0038] The present invention provides a method for preparing the aminosulfonate chain extender described in the above technical scheme, comprising the following steps:

[0039] The diamine, the sulfonic acid substituted propylene derivative, water and the polymerization inhibitor are mixed to carry out an addition reaction to obtain an aqueous solution of an aminosulfonate chain extender;

[0040] The structural formula of the sulfonic acid substituted propylene derivative is H2C=CH-R-SO3R3;

[0041] The structural formula of the diamine is NH2-R1-NH2.

[0042] In the present invention, the diamine is an amine containing two primary amine groups. In the present invention, the diamine preferably includes one or more of ethylenediamine, propylenediamine, butylenediamine, 2-methylpentanediamine, hexamethylenediamine and isophoronediamine. In the present invention, the butylenediamine is preferably 1,4-butylenediamine.

[0043] In the present invention, the sulfonic acid substituted propylene derivative preferably includes one or more of 3-sulfopropyl acrylate, 2-acrylic acid-2-methanesulfonate, acrylic acid-2-alkyl sulfonate, acrylic acid-2-alkyl sulfonate, 2-propylene-1-sulfonic acid, 2-propylene-1-sulfonate, 2-acrylamide-2-methylpropanesulfonic acid and 2-acrylamide-2-methylpropanesulfonic acid, and is specifically preferably 2-propylene-1-sodium sulfonate, 2-propylene-1-sulfonic acid, 2-acrylic acid-2-methanesulfonic acid or 2-acrylamide-2-methylpropanesulfonic acid.

[0044] In the present invention, the molar ratio of the sulfonic acid substituted propylene derivative to the diamine is preferably 1:1 to 1.1.

[0045] In the present invention, the polymerization inhibitor preferably includes one or more of hydroquinone, tert-butylcatechol and p-methoxyphenol; the mass of the polymerization inhibitor is preferably 0.1-1.5% of the mass of the sulfonic acid substituted propylene derivative, more preferably 0.1-0.5%.

[0046] In the present invention, the mixing of the diamine, the sulfonic acid substituted propylene derivative, water and the polymerization inhibitor preferably comprises: dripping the aqueous solution of the sulfonic acid substituted propylene derivative and the polymerization inhibitor into the diamine. In the present invention, the dripping is preferably completed within 2 hours.

[0047] In the present invention, when the sulfonic acid substituted propylene derivative is one or more of 3-sulfopropyl acrylate, 2-propylene-1-sulfonic acid and 2-acrylamide-2-methylpropanesulfonic acid, the raw material for preparing the aminosulfonate chain extender also includes a neutralizer. In the present invention, the neutralizer is preferably an inorganic base, and specifically preferably NaOH. In the present invention, the molar ratio of the neutralizer to the sulfonic acid group in the sulfonic acid substituted propylene derivative is preferably 1:1.

[0048] In the present invention, the addition reaction preferably includes a first addition reaction and a second addition reaction performed sequentially; the temperature of the first addition reaction is preferably 5 to 30°C, more preferably 20 to 30°C; the time of the first addition reaction is preferably 2 to 4 hours, more preferably 3 hours; the temperature of the second addition reaction is preferably 50 to 60°C; the time of the second addition reaction is preferably 2 to 5 hours. In the present invention, the atmosphere of the addition reaction is preferably air or nitrogen.

[0049] In the present invention, after the addition reaction, the obtained reaction system is preferably cooled to room temperature to obtain an aminosulfonate chain extender.

[0050] The present invention provides the use of the aminosulfonate chain extender described in the above technical solution or the aminosulfonate chain extender prepared by the preparation method described in the above technical solution in the preparation of waterborne polyurethane. In the present invention, the solid content of the waterborne polyurethane is preferably 30-40%, more preferably 35%.

[0051] The present invention provides a method for preparing waterborne polyurethane, comprising the following steps:

[0052] A chain extender and an aqueous polyurethane prepolymer containing isocyanate terminal groups are mixed to carry out a chain extension reaction to obtain an aqueous polyurethane; the chain extender is the aminosulfonate chain extender described in the above technical solution or the aminosulfonate chain extender prepared by the preparation method described in the above technical solution.

[0053] In the present invention, the waterborne polyurethane prepolymer containing isocyanate terminal groups preferably includes one or more of waterborne aliphatic polyurethane prepolymers and waterborne aromatic polyurethane prepolymers, and more preferably is a waterborne aliphatic polyurethane prepolymer.

[0054] In the present invention, the molar ratio of the primary amine group in the aminosulfonate chain extender to the isocyanate terminal group in the waterborne polyurethane prepolymer is 0.3 to 0.5:1.

[0055] In the present invention, the mixing of the chain extender and the aqueous polyurethane prepolymer containing isocyanate end groups preferably comprises: adding the chain extender aqueous solution to the aqueous polyurethane prepolymer containing isocyanate end groups. In the present invention, the chain extender aqueous solution is preferably an aminosulfonate chain extender aqueous solution prepared by the preparation method described in the above technical solution. In the present invention, the mass concentration of the chain extender aqueous solution is preferably 30 to 100%, more preferably 50 to 75%.

[0056] In the present invention, the temperature of the chain extension reaction is preferably 2 to 30°C; the time of the chain extension reaction is preferably 1 to 5 hours; the atmosphere of the chain extension reaction is preferably air or nitrogen. In the present invention, the chain extension reaction is preferably carried out under stirring conditions.

[0057] In the present invention, preferably, after the chain extension reaction, the solvent is removed to obtain waterborne polyurethane. In the present invention, the method for removing the solvent is preferably reduced pressure distillation.

[0058] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] Example 1

[0060] Under room temperature and stirring, 601 g of ethylenediamine was added to a reaction kettle, and a solution containing 1441 g of sodium 2-propylene-1-sulfonate, 2 g of p-methoxyphenol and 2042 g of water was added dropwise to the reaction kettle within 2 hours, and the mixture was reacted at room temperature for 4 hours; the mixture was heated to 60° C., reacted for 5 hours, and cooled to room temperature to obtain an aqueous solution A1 of an aminosulfonate chain extender with a mass concentration of 50% suitable for the preparation of waterborne polyurethane.

[0061] The structural formula of the chain extender in the aqueous solution of aminosulfonate chain extender prepared in this embodiment is

[0062]

[0063] The hydrogen spectrum data are: 1 H NMR (400MHz, DMSO-d6) δ5.75 (s, 2H), 4.83 (s, 1H), 3.01 (t, J = 6.1Hz, 2H), 2.9 4(t,J=5.7Hz,2H),2.67(t,J=5.7Hz,2H),2.54(t,J=6.3Hz,2H),1.83(m,2H).

[0064] The carbon spectrum data are: 13C NMR (100MHz, DMSO-d6) δ53.17,51.13,47.42,41.56,23.45.

[0065] Example 2

[0066] Under room temperature and stirring, 601 g of ethylenediamine was added to a reaction kettle, and a solution containing 1221 g of 2-propylene-1-sulfonic acid, 400 g of NaOH, 2 g of p-methoxyphenol and 1862 g of water was added dropwise to the reaction kettle within 2 hours, and the mixture was reacted at room temperature for 3 hours; the mixture was heated to 50° C., reacted for 2 hours, and cooled to room temperature to obtain an aqueous solution A2 of an aminosulfonate chain extender with a mass concentration of 50% suitable for the preparation of waterborne polyurethane.

[0067] The structural formula of the chain extender in the aqueous solution of aminosulfonate chain extender prepared in this embodiment is

[0068]

[0069] The hydrogen spectrum data are: 1 H NMR (400MHz, DMSO-d6) δ5.75 (s, 2H), 4.83 (s, 1H), 3.01 (t, J = 6.1Hz, 2H), 2.9 4(t,J=5.7Hz,2H),2.67(t,J=5.7Hz,2H),2.54(t,J=6.3Hz,2H),1.83(m,2H).

[0070] The carbon spectrum data are: 13 C NMR (100MHz, DMSO-d6) δ53.17,51.13,47.42,41.56,23.45.

[0071] Example 3

[0072] Under room temperature and stirring, 881 g of 1,4-butanediamine was added to a reaction kettle, and a solution of 1441 g of sodium 2-propylene-1-sulfonate, 2 g of p-methoxyphenol and 2322 g of water was added dropwise to the reaction kettle within 2 hours, and the mixture was reacted at room temperature for 3 hours; the mixture was heated to 50° C., reacted for 2 hours, and cooled to room temperature to obtain an aqueous solution of an aminosulfonate chain extender A3 with a mass concentration of 50% suitable for the preparation of waterborne polyurethane.

[0073] The structural formula of the chain extender in the aqueous solution of aminosulfonate chain extender prepared in this embodiment is

[0074]

[0075] The hydrogen spectrum data are: 1H NMR (400MHz, DMSO-d6) δ4.91(s,1H),3.51(s,2H),3.06(t,J=6.3Hz,2H),3.02(dt,J=12.1,6. 3Hz, 4H), 2.54 (t, J = 6.3Hz, 2H), 1.85 (p, J = 6.2Hz, 2H), 1.63-1.52 (m, 2H), 1.43-1.32 (m, 2H).

[0076] The carbon spectrum data are: 13 C NMR (100MHz, DMSO-d6) δ53.12,48.54,47.42,40.65,27.93,24.96,23.41.

[0077] Example 4

[0078] Under room temperature and stirring, 601 g of ethylenediamine was added to a reaction kettle, and a solution containing 2072 g of 3-sulfopropyl acrylate, 400 g of NaOH, 2 g of p-methoxyphenol and 2482 g of water was added dropwise to the reaction kettle within 2 hours, and reacted at room temperature for 3 hours; the temperature was raised to 50° C., reacted for 2 hours, and cooled to room temperature to obtain an aqueous solution A4 of an aminosulfonate chain extender with a mass concentration of 50% suitable for the preparation of waterborne polyurethane.

[0079] The structural formula of the chain extender in the aqueous solution of aminosulfonate chain extender prepared in this embodiment is

[0080]

[0081] The hydrogen spectrum data are: 1 H NMR (400MHz, DMSO-d6) δ8.26 (s, 2H), 4.11-3.93 (m, 2H), 3.01 (t, J = 6.2Hz, 2H), 3.00 -2.87(m,4H),2.64(t,J=5.7,2H),2.52(t,J=6.2Hz,2H),2.03(m,2H),1.33(s,1H).

[0082] The carbon spectrum data are: 13 C NMR (100MHz, DMSO-d6) δ171.13,63.96,52.58,50.84,45.75,41.57,34.79,24.61.

[0083] Example 5

[0084] Under room temperature and stirring, 601 g of ethylenediamine was added to a reaction kettle, and a solution containing 1881 g of 2-acrylamide-2-methylpropanesulfonic acid, 400 g of NaOH, 2 g of p-methoxyphenol and 2684 g of water was added dropwise to the reaction kettle within 2 hours, and the mixture was reacted at room temperature for 3 hours; the mixture was heated to 50° C., reacted for 2 hours, and cooled to room temperature to obtain an aqueous solution of aminosulfonate chain extender A5 with a mass concentration of 50% suitable for the preparation of waterborne polyurethane.

[0085] The structural formula of the chain extender in the aqueous solution of aminosulfonate chain extender prepared in this embodiment is

[0086]

[0087] The hydrogen spectrum data are: 1 H NMR (400MHz, DMSO-d6) δ8.22(s,2H),6.84(s,1H),3.17(s,2H),2.94(t,J=2.2Hz,2H),2 .83(t,J=4.1,2H),2.66(t,J=4.1,2H),2.44(t,J=2.2Hz,2H),1.45(s,6H),1.31(s,1H).

[0088] The carbon spectrum data are: 13 C NMR (100MHz, DMSO-d6) δ170.82,65.20,54.72,50.44,45.23,41.57,38.69,25.29.

[0089] Example 6

[0090] 5000 g of dry polyether diol (DL2000, molecular weight 2000Da, Bluestar Dongda), 1112 g of isophorone diisocyanate, 201 g of dimethylolpropionic acid and 0.50 g of dibutyltin dilaurate were added to the reactor, stirred evenly, heated to 75°C, reacted for 1.5 hours, 2154 g of acetone was added, the reaction was continued for 2 hours, cooled to room temperature, 150 g of triethylamine was added, and stirred for 5 minutes until uniform, to obtain a polyurethane prepolymer solution B1 with a solid content of 75%, which was set aside.

[0091] Example 7

[0092] 5000 g of dried polyether diol (DL2000, molecular weight 2000Da, Bluestar Dongda), 871 g of isotoluene diisocyanate, 201 g of dimethylol propionic acid and 0.50 g of bismuth catalyst (MC-710, Beijing Baiyuan Chemical) were added to the reactor, stirred evenly, heated to 75°C, reacted for 1.5 hours, 2074 g of acetone was added, the reaction was continued for 2 hours, cooled to room temperature, 150 g of triethylamine was added, and stirred for 5 minutes until uniform, to obtain a polyurethane prepolymer solution B2 with a solid content of 75%, which was set aside.

[0093] Application Examples

[0094] Take a certain amount of polyurethane prepolymer solution B1 or B2 of Examples 6 to 7, add a certain amount of 5°C water, stir rapidly for 4 minutes, then add a certain amount of chain extenders A1 to A5 prepared in Examples 1 to 5 or A95 aqueous solution with a solid content of 50% (Comparative Sample 1 and Comparative Sample 2) within 2 minutes, stir for 90 minutes, and remove acetone by vacuum distillation to obtain an aqueous polyurethane with a solid content of 35%. Among them, the aqueous polyurethane prepared by using prepolymer solution B1 is an aqueous fatty polyurethane; the aqueous polyurethane prepared by using prepolymer solution B2 is an aqueous aromatic polyurethane, as shown in Tables 1 and 2.

[0095] Table 1 Water-based fatty polyurethane formed by chain extension of polyurethane prepolymer solution B1

[0096] Waterborne polyurethane Prepolymer solution B1 water Chain Extender Waterborne polyurethane 1 1000g 1153 g A1: 23.6 g Waterborne polyurethane 2 1000g 1153 g A2: 23.6 g Waterborne polyurethane 3 1000g 1154 g A3: 27.0 g Waterborne polyurethane 4 1000g 1155 g A4: 29.0 g Waterborne polyurethane 5 1000g 1159 g A5: 31.3 g Comparison sample 1 1000g 1162 g 50% A95 solution: 44.1 g

[0097] Table 2 Waterborne aromatic polyurethane formed by chain extension of polyurethane prepolymer solution B2

[0098] Waterborne polyurethane Prepolymer solution B2 water Chain Extender Waterborne polyurethane 6 1000g 1154 g A1: 24.4 g Waterborne polyurethane 7 1000g 1154 g A2: 24.4 g Waterborne polyurethane 8 1000g 1155 g A3: 27.9g Waterborne polyurethane 9 1000g 1157 g A4: 30.0g Waterborne polyurethane 10 1000g 1160 g A5: 32.3g Comparison sample 2 1000g 1163 g 50% A95 solution: 46.0 g

[0099] Parameters and results analysis of waterborne polyurethane dispersion

[0100] The basic parameters of waterborne polyurethanes 1 to 10 and comparative samples 1 to 2 are shown in Table 3. Among them, the appearance, solid content, viscosity, freeze-thaw stability and centrifugal stability were tested with reference to GB / T 11175-2002; viscosity test instrument: Brookfield viscometer DV1, determination method: direct test at 25°C. Volatile organic matter: tested with reference to GB / T 23986-2009. Freeze-thaw stability: 50 mL of waterborne polyurethane was placed in a -5±2°C low temperature box, taken out after 18 hours, placed at 23±2°C for 6 hours, and the operation was repeated to observe whether there was precipitation. Centrifugal stability: 30 mL of waterborne polyurethane was placed in a centrifuge, and the centrifugal stability of waterborne polyurethane was tested at 3000r / min, 30min; waterborne polyurethane dispersion particle size test instrument: Zetasizer NanoZS, waterborne polyurethane was diluted with water to a mass concentration of 1%, and tested at 25°C.

[0101] Table 3 Parameters of waterborne polyurethane dispersion

[0102]

[0103] The results in Table 3 show that the particle sizes and stability of waterborne polyurethanes 1 to 10 and comparative samples 1 to 2 are basically the same, indicating that the chain extenders prepared in Examples 1 to 5 and the waterborne polyurethanes prepared by the chain extender sodium ethylenediamine sulfonate (A95) have similar physical properties.

[0104] Analysis of dry film parameters and results of waterborne polyurethane dispersion

[0105] The basic parameters of the waterborne polyurethane dry films of waterborne polyurethanes 1 to 10 and comparative samples 1 to 2 are shown in Table 4. Among them, the test method is: 3 grams of waterborne polyurethane is placed in a polytetrafluoroethylene mold, placed for 2 days, and dried naturally, and then the polyurethane film is dried in a vacuum drying oven at 25°C for 2 days, and its modulus of 100% tensile elongation (referred to as 100% modulus) and elongation at break and glossiness are measured. The 100% modulus of the polyurethane film (the proportional constant of the ratio of its stress to strain when stretched to 100% of the original length) is measured by a tensile testing machine (Shanghai Sonton, WDW-5), and the glossiness is tested using a microscopic three-beam gloss meter (CS-380) at an incident angle of 60°. Alcohol resistance test conditions: 339 rubber alcohol abrasion resistance tester, the solvent is 75% ethanol aqueous solution, and the counterweight is 200 grams.

[0106] Table 4 Dry film performance parameters of waterborne polyurethane

[0107]

[0108]

[0109] The results in Table 4 show that all waterborne polyurethanes are transparent, and the alcohol resistance and glossiness of waterborne polyurethanes prepared using the chain extenders of Examples 1 to 5 are basically consistent with those prepared using the A95 chain extender. The mechanical properties (modulus and elongation at break) of the waterborne polyurethane dry films prepared using the chain extenders of Examples 1 to 4 are basically consistent with those of the waterborne polyurethane dry films prepared using the A95 chain extender, and the mechanical properties of the waterborne polyurethane dry films prepared using the chain extender of Example 5 are slightly worse, among which the 100% modulus and elongation at break of the waterborne fatty polyurethane dry films (Examples 1 to 5 and Comparative Sample 1) are slightly lower than those of the waterborne aromatic polyurethane (Examples 6 to 10 and Comparative Sample 2).

[0110] The above shows that the aminosulfonate chain extender of the present invention is similar to the commonly used A95 chain extender and can be used to prepare waterborne polyurethane with high concentration, small particle size and good stability.

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing waterborne polyurethane, characterized in that: The following steps are involved: A chain extender and an aqueous polyurethane prepolymer containing an isocyanate terminal group are mixed to carry out a chain extension reaction to obtain an aqueous polyurethane; the chain extender is an aminosulfonate chain extender; the aminosulfonate chain extender has a structure shown in Formula I: Formula I; In the formula I, R is ; In the formula I, R1 is an alkylene group; R3 is H, Na or K; In the R, R4 is an alkylene group having 1 to 6 carbon atoms; The preparation method of the aminosulfonate chain extender comprises the following steps: The diamine, the sulfonic acid substituted propylene derivative, water and the polymerization inhibitor are mixed to carry out an addition reaction to obtain an aqueous solution of an aminosulfonate chain extender; The structural formula of the sulfonic acid substituted propylene derivative is ; The structural formula of the diamine is ; The addition reaction comprises a first step addition reaction and a second step addition reaction performed sequentially; the temperature of the first step addition reaction is 5-30° C.; the time of the first step addition reaction is 2-4 hours; the temperature of the second step addition reaction is 50-60° C.; the time of the second step addition reaction is 2-5 hours; The solid content of the waterborne polyurethane is 30-40%.

2. The preparation method according to claim 1, characterized in that: The alkylene group in R1 is an alkylene group having 1 to 6 carbon atoms.

3. The preparation method according to claim 1, characterized in that: The sulfonic acid substituted propylene derivatives include 3-sulfopropyl acrylate.

4. The preparation method according to claim 1 or 3, characterized in that: The molar ratio of the sulfonic acid substituted propylene derivative to the diamine is 1:1 to 1.

1.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the primary amine group in the aminosulfonate chain extender to the isocyanate terminal group in the waterborne polyurethane prepolymer is 0.3-0.5:1.

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