A sulfonic acid type waterborne polyurethane composite with low water absorption, a preparation method thereof, a waterproof coating and application

Abstract

The application discloses a sulfonic acid type water-based polyurethane compound with low water absorption, a preparation method of the sulfonic acid type water-based polyurethane compound, waterproof paint and application of the sulfonic acid type water-based polyurethane compound. The preparation raw material of the sulfonic acid type water-based polyurethane compound comprises polyisocyanate, polyether polyol and / or monohydric alcohol, small molecule dihydric alcohol, amino compound, sulfonate chain extender and hydrophobic film forming modifier. The waterproof paint prepared by using the water-based polyurethane compound of the application does not contain VOCs, has lower water absorption, greater elongation, more excellent comprehensive mechanical properties and better heat resistance, acid resistance and alkali resistance, and is a kind of green and environment-friendly polymer waterproof paint, which can be applied to waterproofing of outer walls, bathrooms, kitchens and basements and the like.

Description

Technical Field

[0001] This invention belongs to the field of waterproof coatings, specifically relating to a sulfonic acid-based waterborne polyurethane composite with low water absorption, its preparation method, and its application. Background Technology

[0002] Waterproofing is crucial in the construction and engineering field, especially in areas prone to water intrusion such as roofs, basements, and bathrooms. Commonly used waterproofing materials include polymer-modified cementitious waterproof coatings, elastomeric waterproof coatings, asphalt waterproofing materials, polyurethane waterproof coatings, and polymer waterproof membranes. Among these, polyurethane waterproof coatings are highly favored due to their excellent waterproofing effect, outstanding elasticity and toughness, excellent substrate adhesion, and ease of application.

[0003] Currently, solvent-based polyurethane waterproof coatings are still the dominant type on the market, and can be divided into single-component and two-component polyurethane waterproof coatings. Single-component polyurethane waterproof coatings mix terminal-NCO prepolymers with inorganic pigments / fillers, additives, and solvents in a specific ratio. After application, during the solvent evaporation and film formation process, the isocyanate groups of the prepolymer react with the substrate or moisture in the air to establish strength. Two-component polyurethane waterproof coatings establish strength and performance through the reaction of the prepolymer with a curing agent or latent curing agent. However, solvent-based polyurethane waterproof coatings have serious drawbacks. During use, they emit high levels of volatile organic compounds (VOCs) into the environment, seriously endangering the health of construction workers and users, and causing environmental pollution.

[0004] CN104194610B discloses a self-crosslinking single-component polyurethane waterproof coating. It introduces a diacetone acrylamide structure into the molecular chain through a specially structured modifier, achieving self-crosslinking via ketone-hydrazine crosslinking. This water-based polyurethane waterproof coating has no NCO residue and is non-toxic and environmentally friendly. However, its water resistance is insufficient, significantly different from that of oil-based polyurethane.

[0005] CN105622878B discloses a silicon-fluorine modified waterborne polyurethane waterproof coating, which improves the hydrophobic effect by introducing silicon and fluorine elements into the polyurethane molecular chain. However, after the coating is soaked in water for 24 hours, the water absorption rate exceeds 7.1%, which is far from meeting the standard of less than 5% water absorption rate after 7 days of immersion. Therefore, it does not achieve a good waterproof effect. In addition, the raw material cost is high and the industrialization value is not significant.

[0006] CN115710455B discloses a sulfonate-based waterborne polyurethane waterproof coating. A waterborne polyurethane waterproof coating with good controllability and good emulsion stability is prepared by self-made modified sulfonic acid hydrophilic chain extender. However, the water absorption rate of the waterproof coating is still too high, and the elongation and tensile strength are insufficient.

[0007] Therefore, there is a need to develop a new type of solvent-free polyurethane waterproof coating with performance close to that of solvent-based waterproof coatings. Summary of the Invention

[0008] To address the aforementioned shortcomings in existing technologies, one objective of this invention is to provide a novel solvent-free polyurethane waterproof coating and its applications that exhibit performance similar to solvent-based waterproof coatings. Another objective of this invention is to provide a low-absorption sulfonic acid-based waterborne polyurethane composite and its preparation method.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A sulfonic acid-based waterborne polyurethane composite with low water absorption rate is prepared from raw materials comprising the following components:

[0011] S1, one or more polyisocyanates;

[0012] S2, one or more polyether polyols and / or polyether monools, having an average molecular weight of 400-4500 g / mol, preferably 600-3000 g / mol, more preferably 2000 g / mol;

[0013] S3, one or more small molecule diols, as chain extenders, which contain at least two groups that can react with isocyanates and have an average molecular weight of 60-499 g / mol;

[0014] S4, one or more amino compounds, namely polyamine small molecule chain extenders containing active hydrogen, with an average molecular weight of 60-499 g / mol;

[0015] S5, one or more sulfonate chain extenders containing two groups that can react with isocyanates, having an average molecular weight of 100-700 g / mol;

[0016] S6. One or more hydrophobic film-forming modifiers having an average molecular weight of 150-3000 g / mol, preferably 250-1500 g / mol; and a water absorption rate preferably ≤5%, more preferably ≤2%.

[0017] S7, Water;

[0018] S8, an optional catalyst that can catalyze the reaction between isocyanate groups and hydroxyl groups;

[0019] S9, an organic solvent that does not contain groups capable of reacting with isocyanates.

[0020] In this invention, in the above-mentioned low-water-absorption sulfonic acid-based waterborne polyurethane composite,

[0021] Based on the total mass of components S1-S6:

[0022] The amount of component S1 is 15.5-24.5 wt%, preferably 17-22 wt%.

[0023] The amount of component S2 is 50-65 wt%, preferably 55-60 wt%;

[0024] The amount of component S3 is 1.0-6.0 wt%, preferably 2.3-4.8 wt%;

[0025] The amount of component S4 is 0.1-2.5 wt%, preferably 0.6-1.6 wt%.

[0026] The amount of component S5 is 1.0-7.0 wt%, preferably 1.6-5.0 wt%.

[0027] The amount of component S6 is 2-25 wt%, preferably 12-20 wt%.

[0028] Based on the total mass of components S1-S3:

[0029] The amount of component S8 is 0-2000 ppm, preferably 100-500 ppm;

[0030] The amount of component S9 is 0.7-3.0 times, preferably 1.0-2.2 times.

[0031] In this invention, the polyisocyanate in component S1 of the aforementioned low-water-absorption sulfonic acid-based waterborne polyurethane composite includes, but is not limited to, one or more of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4-cyclohexyl diisocyanate, 1,5-naphthalene diisocyanate, p-phenylenemethylene diisocyanate, p-phenylenediamine diisocyanate, 2,4-ethylphenyl diisocyanate, methylcyclohexyl diisocyanate, and isopropylidene dicyclohexyl isocyanate; more preferably, one or more of toluene diisocyanate and dicyclohexylmethane diisocyanate.

[0032] In this invention, in component S2 of the aforementioned low-water-absorption sulfonic acid-based waterborne polyurethane composite, the polyether polyol and / or polyether monohydric alcohol includes, but is not limited to, one or more of polyether monohydric alcohol and polyether dihydric alcohol; preferably, the polyether polyol and / or polyether monohydric alcohol in component S2 is a mixture of polyether monohydric alcohol and polyether dihydric alcohol; more preferably, the content of polyether monohydric alcohol in the mixture is 0.4-2.0% and the content of polyether dihydric alcohol is 98.0-99.6% based on its total weight;

[0033] Preferably, the polyether monohydric alcohol is a monohydroxy polyoxyethylene ether, and its number average molecular weight is preferably 350-3000 g / mol, more preferably 520-2200 g / mol;

[0034] Preferably, the polyether diol is one or both of polypropylene glycol and polybutane glycol; the number average molecular weight of the polyether diol is preferably 400-4000 g / mol, more preferably 650-3000 g / mol, such as DL-2000D and DL-3000D from Lanxing Dongda, and Wanhua Chemical's... 2010D, 2030, BASF's PTMEG-1000 and PTMG-2000.

[0035] In this invention, the small molecule diol in component S3 of the aforementioned low water absorption sulfonic acid-based waterborne polyurethane composite includes, but is not limited to, one or more of ethylene glycol, diethylene glycol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanediol, 1,6-hexanediol, and neopentyl glycol; preferably one or more of neopentyl glycol, 1,4-butanediol, and 1,4-cyclohexanediol.

[0036] In this invention, in component S4 of the aforementioned low-water-absorption sulfonic acid-based waterborne polyurethane composite, the amino compound is selected from one or more of aromatic, aliphatic, and alicyclic polyamines, including but not limited to two or more mixtures of 4,4'-diaminodiphenylmethane, ethylenediamine, 2-methylpentanediamine, N-hydroxyethylethylenediamine, isophoronediamine, 1,6-hexanediamine, 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; more preferably, it is a mixture of two or three of ethylenediamine, hydroxyethylethylenediamine, 4,4'-diaminodicyclohexylmethane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0037] In this invention, in component S5 of the aforementioned low water absorption sulfonic acid type waterborne polyurethane composite, the sulfonate chain extender includes, but is not limited to, one or more of small molecule sulfonic acid type diols (S5-1) and small molecule sulfonic acid type diamines (S5-2); the number average molecular weight of the sulfonate chain extender is preferably 100-700 g / mol, more preferably 190-550 g / mol, such as sulfonic acid type diol PO204 from Taiwan Double Bond, sodium 2-[(2-aminoethyl)amino]ethanesulfonate from Wanhua, and sodium 2-[(2-aminoethyl)amino]propanesulfonate from Ruierfeng.

[0038] In this invention, in component S6 of the above-mentioned low water absorption sulfonic acid type waterborne polyurethane composite, the hydrophobic film-forming modifier is selected from one or more of epoxy resin ring-opening adducts, chlorinated derivatives of paraffin hydrocarbons, and polyether type polyurethane oligomers, and its number average molecular weight is preferably 150-3000 g / mol, more preferably 250-1500 g / mol.

[0039] Preferably, the epoxy resin ring-opening adduct is a ring-opening adduct of epoxy resin and a monoalkyl alcohol, wherein the monoalkyl alcohol has 4-30 carbon atoms.

[0040] Preferably, the chlorinated derivative of the paraffinic hydrocarbon is a chlorinated derivative of C8-C26 paraffinic hydrocarbon, and the chlorination rate is 40-70% of the total weight.

[0041] Preferably, the polyether-type polyurethane oligomer is an adduct of polyisocyanate with polyether diol or monoalkyl alcohol.

[0042] In this invention, the solid content of the above-mentioned low water absorption sulfonic acid type waterborne polyurethane composite is preferably 40-65 wt%, more preferably 45-55 wt%; the average particle size of its solid content is preferably in the range of 150-650 nm, more preferably in the range of 200-400 nm.

[0043] In another aspect of the present invention, a method for preparing the low water absorption sulfonic acid-based waterborne polyurethane composite is also provided, comprising the following steps:

[0044] 1) Mix components S1, S2, S3, S8, a portion of component S9 and optional component S5-1, and react at 65-85℃ until NCO reaches the theoretical value to generate a diisocyanate-terminated prepolymer.

[0045] 2) Cool the prepolymer obtained in step 1) to 25-55℃, add component S6 and the remaining component S9 and stir to mix evenly;

[0046] 3) Add component S4 and optional component S5-2 to the prepolymer dilution solution obtained in step 2), and react at 25-55℃ for 5-25 min;

[0047] 4) Under high-speed stirring, add component S7 to the polyurethane solution obtained in step 3) to obtain a crude emulsion, remove the solvent, and obtain a sulfonic acid type waterborne polyurethane composite with low water absorption.

[0048] Of these, at least one of components S5-1 and S5-2 must be added.

[0049] Preferably, in steps 1) and 2), the mass ratio of the amount of component S9 added is 1 / (6-15), for example, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, etc.

[0050] Preferably, in step 3), component S4 and optional component S5-2 are added in the form of an aqueous solution or an acetone solution, and the amount of water or acetone used is 1-20 times the total mass of component S4 and component S5-2, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 times, etc.

[0051] In this invention, a waterborne polyurethane waterproof coating is also provided, which comprises the aforementioned low water absorption sulfonic acid type waterborne polyurethane composite.

[0052] In one specific implementation, the waterborne polyurethane waterproof coating, in addition to the aforementioned low-water-absorption sulfonic acid-based waterborne polyurethane composite, also includes one or more of pigments / fillers, dispersants, defoamers, film-forming aids, stabilizers, wetting agents, and thickeners.

[0053] This invention also provides an application of water-based polyurethane waterproof coating in the field of building waterproofing, which is particularly suitable for waterproofing roofs, exterior walls, bathrooms, kitchens and basements.

[0054] The beneficial effects of this invention are mainly reflected in the following aspects:

[0055] (1) This invention differs from general sulfonic acid-based waterborne polyurethane emulsions. It adopts a core-shell structure design concept, with a hydrophobic film-forming modifier as the core and a hydrophilic polyurethane as the shell. The hydrophobic film-forming modifier has a relatively small molecular weight, which can fill the gaps that exist when latex particles are fused, improve the film-forming properties of the emulsion, enhance the density of the coating film, significantly reduce the water absorption rate of the coating film, and at the same time improve the overall mechanical properties of the paint film to a certain extent.

[0056] (2) This invention differs from general waterborne polyurethane waterproof coatings. The waterborne polyurethane waterproof coating prepared using this sulfonic acid type waterborne polyurethane composite has a lower water absorption rate, better comprehensive mechanical properties, and better heat / acid / alkali resistance. Detailed Implementation

[0057] The following embodiments are further illustrations of the present invention, but not limitations on its scope. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the invention, and all such modifications and substitutions should be covered by the claims of the present invention. Within the scope of the present invention, the above-described technical features and the technical features specifically described below (such as in the embodiments) can be combined with each other to constitute new or preferred technical solutions.

[0058] I. Source of main raw materials in the example:

[0059] Polytetrahydrofuran ether diol: Industrial grade, molecular weight 2000 g / mol, BASF Ltd.;

[0060] Polypropylene glycol: Industrial grade, molecular weight 2000 g / mol, Wanhua Chemical Group Co., Ltd.

[0061] Catalyst: Bi@8108, industrial grade, Leading Inc., USA;

[0062] Neopentyl glycol: Industrial grade, Wanhua Chemical Group Co., Ltd.

[0063] 1,4-Cyclohexanediethanol, Industrial Grade, Alfaesa Chemicals Ltd.;

[0064] 1,4-Butanediol: Industrial grade, Wanhua Chemical Group Co., Ltd.;

[0065] Acetone: Industrial grade, Wanhua Chemical Group Co., Ltd.;

[0066] 4,4-Dicyclohexylmethane diisocyanate: Industrial grade, Wanhua Chemical Group Co., Ltd.;

[0067] Isophorone diisocyanate: Industrial grade, Wanhua Chemical Group Co., Ltd.;

[0068] Toluene diisocyanate: Industrial grade, Wanhua Chemical Group Co., Ltd.

[0069] Ethylenediamine: Analytical grade, Sinopharm Chemical Reagent Co., Ltd.;

[0070] 4,4'-Diaminodicyclohexylmethane: Industrial grade, Wanhua Chemical Group Co., Ltd.;

[0071] N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane: Industrial grade, Yunsheng Chemical Co., Ltd.;

[0072] Small molecule sulfonic acid diamine A95: Industrial grade, Wanhua Chemical Group Co., Ltd.;

[0073] Small molecule sulfonic acid diol PO2O4: Industrial grade, Double Bond Chemical Co., Ltd., Taiwan, China;

[0074] Polyethylene glycol monomethyl ether: industrial grade, molecular weight 1200 g / mol, Hanong Chemical Co., Ltd.;

[0075] 42# - Chlorinated derivatives of medium-chain paraffinic hydrocarbons: Industrial grade, Donghong Environmental Protection Materials Technology Co., Ltd.

[0076] Epoxy resin E44: Industrial grade, Sinopec;

[0077] PPG-600: Industrial grade, Wanhua Chemical Group Co., Ltd.

[0078] Guerbert alcohol hexadecyl: Industrial grade, Sasol Chemicals;

[0079] Guerbert alcohol twelve: Industrial grade, Sasol Chemicals;

[0080] Boron trifluoride ether: analytical grade, Sinopharm Group.

[0081] II. Analytical Instruments and Testing Methods:

[0082] All tests were conducted under standard test conditions: temperature 23±2℃, relative humidity 50±10%. The final coating thickness was required to be controlled at 1.5±0.2mm. The prepared coating was cured under standard test conditions for 96 hours before demolding, flipped over, and then cured in an electric heating drying oven at 40±2℃ for another 48 hours. After removal, it was placed under standard test conditions for 4 hours.

[0083] Solid content test: The test shall be conducted in accordance with Chapter 5 of GB / T16777-2008;

[0084] Particle size testing method: Malvern particle size analyzer was used;

[0085] Water absorption rate: Tested according to 6.15 of GB / T19250-2013;

[0086] Tensile properties: Tested according to 6.9 of GB / T 19250-2013;

[0087] Alkali treatment: According to the test method for water-based coatings in 9.2.3 of GB / T16777-2008;

[0088] Acid treatment: According to the test method for water-based coatings in 9.2.4 of GB / T16777-2008.

[0089] 1) Preparation of epoxy resin ring-opening adducts:

[0090] 227.3g of epoxy resin E44 and 242.5g of Gelbert alcohol hexadecyl were heated to 65°C and stirred until homogeneous; then 4.70g of boron trifluoride ether was added and the reaction was maintained at this temperature for 6 hours to obtain the epoxy resin ring-opening adduct EPA.

[0091] 2) Preparation of polyether-type polyurethane oligomers:

[0092] 174.9g HMDI, 200g PPG600 and 0.1g Bi@8108 were heated to 75℃ and reacted for 1.5h. Then 124.3g Gelbert alcohol dodecyl was added and the reaction was continued at this temperature for another 1.5h to obtain polyether-type polyurethane oligomer PUO.

[0093] 3) Preparation of waterborne polyurethane composites

[0094] Example 1

[0095] Heat 280.00g DL-2000D, 3.20g MPEG1200, and 13.62g NPG to 60℃ and stir until well mixed. Then add 104.80g HMDI was added, and finally 44.22g of acetone and 0.12g of Bi@8108 catalyst were added. The mixture was heated to 75℃ and reacted for 4 hours to generate a prepolymer with isocyanate groups at the end.

[0096] Lower the temperature to below 50℃, add 78.87g of epoxy resin ring-opening adduct EPA and 530.72g of acetone to the prepolymer, mix well, then add 6.52g of hydroxyethyl ethylenediamine and 9.18g of A95 (diluted with 47.10g of water) by meter. Continue the reaction at 45℃ for 10min, then add 1.33g of KH-792 (diluted with 13.30g of acetone) and continue the reaction for 15min.

[0097] Add 445.83 g of deionized water to the disperser at a speed of 1200-1500 r / min under shear dispersion conditions, and continue stirring for 25 min. Finally, remove acetone by vacuum distillation to obtain an aqueous polyurethane dispersion with a solid content of 50% and a particle size of 269 nm.

[0098] Example 2

[0099] Heat 292.00g DL-2000D, 4.18g MPEG1200, and 23.35g 1,4-cyclohexanediethanol to 60℃ and stir until well mixed. Then add 54.22g HMDI and 36.00g TDI-80 was then added, followed by 39.09g of acetone and 0.07g of Bi@8108 catalyst. The mixture was heated to 75℃ and reacted for 4 hours to produce a prepolymer with isocyanate groups at the end.

[0100] Lower the temperature to below 50℃, add 100.73g of chlorinated derivative of 42-medium-chain paraffin hydrocarbon and 469.14g of acetone to the prepolymer, mix well, then add 2.08g of ethylenediamine and 9.68g of A95 (diluted with 35.27g of water) by meter, and continue the reaction at 45℃ for 10min. Then add 1.67g of KH-792 (diluted with 16.70g of acetone) and continue the reaction for 15min.

[0101] Add 483.80 g of deionized water to the disperser at a speed of 1200-1500 r / min under shear dispersion conditions, and continue stirring for 25 min. Finally, remove acetone by vacuum distillation to obtain an aqueous polyurethane dispersion with a solid content of 50% and a particle size of 348 nm.

[0102] Example 3

[0103] Heat 280.00g PTMEG2000, 4.20g MPEG1200, 22g PO2O4, and 11.79g 1,4-butanediol to 60°C and stir until well mixed. Then add 104.80g... HMDI was added, and finally 50g of acetone and 0.07g of Bi@8108 catalyst were added. The mixture was heated to 75℃ and reacted for 6 hours to generate a prepolymer with isocyanate groups at the end.

[0104] Lower the temperature to below 50℃, add 58.23g of polyether-type polyurethane oligomer PUO and 530.72g of acetone to the prepolymer, mix well, then add 2.44g of ethylenediamine and 1.21g of 4,4'-diaminodicyclohexylmethane (diluted with 68.4g of acetone), and continue the reaction at 45℃ for 10min. Then add 1.12g of KH-792 (diluted with 13.30g of acetone) and continue the reaction for 10min.

[0105] Under shear dispersion conditions with the disperser speed adjusted to 1200-1500 r / min, 485.22 g of deionized water was added, and stirring was continued for 25 min. Finally, acetone was removed by vacuum distillation to obtain an aqueous polyurethane dispersion with a solid content of 50% and a particle size of 297 nm.

[0106] Comparative Example 1

[0107] Heat 292.00g DL-2000D, 4.18g MPEG1200, and 23.35g 1,4-cyclohexanediethanol to 60℃ and stir until well mixed. Then add 54.22g HMDI and 36.00g TDI-80 was then added, followed by 39.09g of acetone and 0.07g of Bi@8108 catalyst. The mixture was heated to 75℃ and reacted for 4 hours to produce a prepolymer with isocyanate groups at the end.

[0108] Lower the temperature to below 50℃, add 469.14g of acetone to the prepolymer, mix well, then add 2.08g of ethylenediamine and 9.68g of A95 (diluted with 35.27g of water) by meter. Continue the reaction at 45℃ for 10min, then add 1.67g of KH-792 (diluted with 16.70g of acetone) and continue the reaction for 15min.

[0109] Under shear dispersion conditions with the disperser speed adjusted to 1200-1500 r / min, 435.41 g of deionized water was added (ensuring the solid content was comparable to that in Example 2), and stirring was continued for 25 min. Finally, acetone was removed by vacuum distillation to obtain an aqueous polyurethane dispersion with a solid content of 50% and a particle size of 277 nm.

[0110] Comparative Example 2

[0111] Heat 320.00g DL-2000D, 4.20g MPEG1200, 11.36g neopentyl glycol, and 5.46g 2,2-dimethylolpropionic acid to 60℃ and stir until well mixed. Then add 93.39g IPDI was then added, followed by 43.45 g of acetone and 0.18 g of Bi@8108 catalyst. The mixture was heated to 75 °C and reacted for 6 hours to produce a prepolymer with isocyanate groups at the end.

[0112] Lower the temperature to below 40℃, add 105.35g of chlorinated derivative of 42-medium chain paraffin hydrocarbon and 347.67g of acetone to the prepolymer, mix well, add 3.50g of triethylamine to neutralize for 10min, and then add 1.22g of KH-792 (diluted with 12.2g of acetone) to extend the chain for 5min.

[0113] Under shear dispersion conditions with the disperser speed adjusted to 1200-1500 r / min, 511.28 g of deionized water was added, followed by 1.97 g of ethylenediamine and 5.50 g of isophorone diamine (diluted with 37.35 g of water), and stirring was continued for 25 min. Finally, acetone was removed by vacuum distillation to obtain an aqueous polyurethane dispersion with a solid content of 50% and a particle size of 485 nm.

[0114] Comparative Example 3

[0115] Heat 320.00g DL-2000D, 4.20g MPEG1200, 7.37g neopentyl glycol, and 10.6g 2,2-dimethylolpropionic acid to 60℃ and stir until well mixed. Then add 93.39g... IPDI was then added, followed by 43.56 g of acetone and 0.18 g of Bi@8108 catalyst. The mixture was heated to 75 °C and reacted for 6 hours to produce a prepolymer with isocyanate groups at the end.

[0116] Lower the temperature to below 40℃, add 105.35g of chlorinated derivative of 42-medium chain paraffin hydrocarbon and 348.59g of acetone to the prepolymer, mix well, add 6.79g of triethylamine to neutralize for 10min, and then add 1.22g of KH-792 (diluted with 12.2g of acetone) to extend the chain for 5min.

[0117] Under shear dispersion conditions with the disperser speed adjusted to 1200-1500 r / min, 512.25 g of deionized water was added, followed by 1.97 g of ethylenediamine and 5.50 g of isophorone diamine (diluted with 37.35 g of water), and stirring was continued for 25 min. Finally, acetone was removed by vacuum distillation to obtain an aqueous polyurethane dispersion with a solid content of 50% and a particle size of 287 nm.

[0118] In Examples 1-3, the sodium sulfonate content accounted for 0.50-0.86% of the resin mass fraction. In Comparative Example 2, the carboxylate content, converted to sodium sulfonate, accounted for 0.77% of the resin mass fraction, which is basically consistent with the examples, but the emulsion stability deviated, and the emulsion broke during pulping. Therefore, the carboxylate content in Comparative Example 3 was increased to ensure emulsion stability. In Comparative Example 3, the carboxylate content, converted to sodium sulfonate, accounted for 1.48% of the resin mass fraction.

[0119] Preparation of waterborne polyurethane waterproof coating:

[0120] After the stabilizer is added to water and dispersed evenly, the dispersant, wetting agent, defoamer and film-forming aid are added. The mixture is stirred at 100-300 rpm to ensure that the above materials are evenly dispersed in water. Then, the filler is added in two batches and dispersed evenly. The waterborne polyurethane dispersions prepared in the examples and comparative examples are added separately and stirred until the dispersion and slurry are evenly mixed. Finally, a thickener is added to adjust the viscosity to 2000-6000 cP to obtain the waterborne polyurethane waterproof coating.

[0121] 45 parts of waterborne polyurethane dispersion; 42 parts of filler (precipitated barium sulfate); 1.5 parts of dispersant (731A); 0.8 parts of defoamer (A10); 0.5 parts of film-forming aid (Texanol); 0.1 parts of stabilizer (cellulose HE-10K); 0.2 parts of wetting agent (BD109); 0.1 parts of thickener (U505); and 9.8 parts of water.

[0122] The specific performance test data is shown in the table below:

[0123] surface 1 1. Mechanical and waterproof properties of water-based polyurethane waterproof coatings

[0124]

[0125] The tensile strength retention rate of the above-mentioned cured coating after heat / acid / alkali treatment is 100% to 120%, and the elongation at break is not less than 750%. The specific results are shown in Table 2.

[0126] surface 2 2. Mechanical properties of water-based polyurethane waterproof coating film after heat / acid / alkali treatment

[0127]

[0128] Note: In Comparative Example 3, blistering occurred on the surface of the paint film after alkali treatment.

[0129] As shown in Tables 1 and 2, the waterborne polyurethane waterproof coatings prepared using the sulfonic acid-based waterborne polyurethane composites in Examples 1-3 have lower water absorption and greater elongation. Furthermore, the overall performance of the coating film remains good after heat / acid / alkali treatment, making it highly valuable for industrialization.

Claims

1. A sulfonic acid-based waterborne polyurethane composite with low water absorption, characterized in that, It is prepared from the following raw materials: S1, polyisocyanates; S2, polyether polyol or polyether polyol and polyether monohydric alcohol, having an average molecular weight of 400-4500 g / mol; S3, a small molecule diol, which contains at least two groups that can react with isocyanates and has an average molecular weight of 60-499 g / mol; S4, amino compounds, have an average molecular weight of 60-499 g / mol; S5, a sulfonate chain extender, contains two groups that can react with isocyanates and has an average molecular weight of 100-700 g / mol; S6, a hydrophobic film-forming modifier with an average molecular weight of 150-3000 g / mol; S7, Water; S8, an optional catalyst that can catalyze the reaction between isocyanate groups and hydroxyl groups; S9, an organic solvent that does not contain any groups that can react with isocyanates; Based on the total mass of components S1-S6: The amount of component S1 used is 15.5-24.5 wt%; The amount of component S2 used is 50-65 wt%; The amount of component S3 used is 1.0-6.0 wt%; The amount of component S4 used is 0.1-2.5 wt%; The amount of component S5 used is 1.0-7.0 wt; The amount of component S6 used is 2-25 wt%; Based on the total mass of components S1-S3: The amount of component S8 used is 0-2000 ppm; The amount of component S9 used is 0.7-3.0 times; The sulfonate chain extender of component S5 is selected from one or more of small molecule sulfonic acid diols (S5-1) and small molecule sulfonic acid diamines (S5-2); The hydrophobic film-forming modifier of component S6 is selected from one or more of epoxy resin ring-opening adducts, chlorinated derivatives of paraffin hydrocarbons, and polyether-type polyurethane oligomers; the epoxy resin ring-opening adduct is a ring-opening adduct of epoxy resin and a monoalkyl alcohol, wherein the monoalkyl alcohol has 4-30 carbon atoms; the polyether-type polyurethane oligomer is an adduct of polyisocyanate and polyether diol or monoalkyl alcohol. The method for preparing the low water absorption sulfonic acid-based waterborne polyurethane composite includes the following steps: 1) Mix components S1, S2, S3, S8, a portion of component S9 and optional component S5-1, and react at 65-85℃ until NCO reaches the theoretical value to generate a diisocyanate-terminated prepolymer. 2) Cool the prepolymer obtained in step 1) to 25-55℃, add component S6 and the remaining S9 and stir to mix evenly; 3) Add component S4 and optional component S5-2 to the prepolymer dilution solution obtained in step 2), and react at 25-55℃ for 5-25 min; 4) Under high-speed stirring, add component S7 to the polyurethane solution obtained in step 3) to obtain a crude emulsion, remove the solvent, and obtain a sulfonic acid type waterborne polyurethane composite with low water absorption. At least one of component S5-1 and component S5-2 is added.

2. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 1, characterized in that, Based on the total mass of components S1-S6: The amount of component S1 used is 17-22 wt%. The amount of component S2 used is 55-60 wt%; The amount of component S3 used is 2.3-4.8 wt%; The amount of component S4 used is 0.6-1.6 wt%; The amount of component S5 used is 1.6-5.0 wt%; The amount of component S6 used is 12-20 wt%; Based on the total mass of components S1-S3: The amount of component S8 used is 100-500 ppm; The amount of component S9 used is 1.0-2.2 times.

3. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 1 or 2, characterized in that, The component S2 is a polyether polyol or a combination of polyether polyol and polyether monohydric alcohol, having an average molecular weight of 600-3000 g / mol.

4. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 1 or 2, characterized in that, The polyisocyanate of component S1 is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4-cyclohexyl diisocyanate, 1,5-naphthalene diisocyanate, p-phenylmethylene diisocyanate, p-phenylenediamine diisocyanate, 2,4-ethylphenyl diisocyanate, and methylcyclohexyl diisocyanate. And / or, component S2 is a mixture of polyether monohydric alcohol and polyether dihydric alcohol; And / or, the small molecule diol of component S3 is selected from one or more of ethylene glycol, diethylene glycol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanediol, 1,6-hexanediol and neopentyl glycol; And / or, the amino compound of component S4 is selected from one or more of aromatic, aliphatic, and alicyclic polyamines.

5. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 4, characterized in that, The polyisocyanate of component S1 is selected from one or more of toluene diisocyanate and dicyclohexylmethane diisocyanate; And / or, based on its total weight, component S2 of the mixture contains 0.4-2.0% polyether monohydric alcohol and 98.0-99.6% polyether dihydric alcohol; And / or, the small molecule diol of component S3 is selected from one or more of neopentyl glycol, 1,4-butanediol, and 1,4-cyclohexanediol; And / or, the amino compound of component S4 is selected from two or more mixtures of 4,4'-diaminodiphenylmethane, ethylenediamine, 2-methylpentanediamine, N-hydroxyethylethylenediamine, isophoronediamine, 1,6-hexanediamine, 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; And / or, the number average molecular weight of the sulfonate chain extender of component S5 is 100-700 g / mol.

6. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 5, characterized in that, The polyether monohydric alcohol in component S2 is a monohydroxy polyethylene oxide ether with a number average molecular weight of 350-3000 g / mol, and the polyether dihydric alcohol is one or both of polypropylene glycol and polybutane glycol; the number average molecular weight of the polyether dihydric alcohol is 400-4000 g / mol. And / or, the amino compound of component S4 is a mixture of two or three of the following: ethylenediamine, hydroxyethylethylenediamine, 4,4'-diaminodicyclohexylmethane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; And / or, the number average molecular weight of the sulfonate chain extender of component S5 is 190-550 g / mol.

7. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 6, characterized in that, The number-average molecular weight of the polyether monohydric alcohol in component S2 is 520-2200 g / mol; The number-average molecular weight of the polyether diol is 650-3000 g / mol.

8. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 1, characterized in that, In steps 1) and 2), the mass ratio of the amount of component S9 added is 1 / (6-15).

9. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 8, characterized in that, In step 3), component S4 and optional component S5-2 are added in the form of an aqueous solution or an acetone solution, and the amount of water or acetone used is 1-20 times the total mass of component S4 and component S5-2.

10. The low water absorption sulfonic acid-based waterborne polyurethane composite according to claim 1, characterized in that, The prepared low-water-absorption sulfonic acid-based waterborne polyurethane composite is in emulsion form, with a solid content of 40-65% and a particle size of 180-650 nm.

11. A water-based polyurethane waterproof coating, characterized in that, The sulfonic acid-based waterborne polyurethane composite comprising the low water absorption rate as described in any one of claims 1-10.

12. The waterborne polyurethane waterproof coating according to claim 11, characterized in that, It also includes one or more of the following: pigments, fillers, dispersants, defoamers, film-forming aids, stabilizers, wetting agents, and thickeners.

13. The application of the waterborne polyurethane waterproof coating according to claim 11 or 12 in the field of building waterproofing.

14. The application according to claim 13, characterized in that, Suitable for waterproofing roofs, exterior walls, bathrooms, kitchens, and basements.

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