Preparation method of cationic polyurethane waterproof agent dispersion

Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a preparation method of a cationic polyurethane waterproofing agent dispersoid, which comprises the following steps: A, reacting glycidyl with double long-chain alkyl secondary amine to obtain a chain extender; b, adding the polyurethane prepolymer into a chain extender for reaction, then adding acid for reaction, and stirring and dispersing in deionized water to obtain a cationic polyurethane waterproof agent dispersion; according to the prepared cationic waterproof agent dispersion, the problem of foam caused by introduction of a large amount of emulsifier in the using process of a conventional waterproof agent emulsion is solved, and the negative influence on the waterproof effect caused by enrichment of micromolecular emulsifier on the surface of a membrane is also avoided. Besides, in the polyurethane film forming process, the surface energy can be effectively reduced through the enrichment and crystallization effects of a long-chain alkyl side chain on the surface, and an excellent waterproof effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a method for preparing a cationic polyurethane waterproofing agent dispersion. Background Art

[0002] Waterproofing of textiles is a common finishing process, which can greatly expand the application scenarios of textiles by making them waterproof. In the current printing and dyeing process, cationic polyacrylate emulsions containing perfluoroalkyl side chains are widely used as waterproof agents for textiles. The perfluoroalkyl side chains with extremely low surface energy are enriched on the surface of the fabric, making the finished fabric have extremely low surface energy, thereby achieving waterproof and even oil-proof properties.

[0003] With increasingly stringent environmental regulations, the use of fluorine-containing waterproofing agents will be restricted, and fluorine-free waterproofing agents will gradually become the mainstream choice in the market. Fluorine-free waterproofing agents do not contain fluorine elements and will not pollute the environment during production and use. The fluorine-free waterproofing agents on the market are mainly cationic polyacrylate emulsions. During the preparation process of such products, long-chain alkyl (meth) acrylates with strong hydrophobicity and acrylate monomer copolymers are generally added, as well as silicone oils with low surface energy. The synergistic effect of silicone oil and long-chain alkyl enables such products to achieve better waterproof performance. However, in the preparation process of such products, cationic emulsifiers are generally used to provide stability, which causes such products to produce more foam during use and are prone to foam spots. In addition, cationic emulsifiers are easy to migrate to the surface during film formation, and the enrichment of hydrophilic groups on the surface will also have a negative impact on the waterproofing effect.

[0004] During the preparation process of waterborne polyurethane, no emulsifier is required. It relies on the self-emulsification effect of the hydrophilic groups on the molecular chain to achieve stability. Therefore, using waterborne polyurethane as a waterproofing agent can effectively avoid the problems of foam and surfactant enrichment on the film-forming surface that occur in traditional acrylic waterproofing agents, and the excellent film-forming properties of polyurethane can effectively enhance the application effect of the waterproofing agent. During the preparation process of waterborne polyurethane waterproofing agents, although the reaction of hydroxyl silicone oil and isocyanate groups can effectively introduce organic siloxanes into the polyurethane molecular chain, the waterproof performance can be improved to a certain extent. However, in the preparation process of fluorine-free waterproofing agents, the enrichment and crystallization of long-chain alkyl side chains on the surface are the key factors that determine the quality of waterproofing performance. At present, in the preparation process of waterborne polyurethane, there is a lack of methods for introducing long-chain alkyl groups into the polyurethane side chains, which leads to poor waterproofing effect of polyurethane waterproofing agents.

[0005] In view of the above problems, the market urgently needs to improve the existing polyurethane waterproofing agents to overcome the existing defects. Summary of the invention

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a method for preparing a cationic polyurethane waterproofing agent dispersion.

[0007] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: The present invention provides a method for preparing a cationic polyurethane waterproofing agent dispersion, comprising the following steps: A. reacting glycidol with a di-long chain alkyl secondary amine to obtain a chain extender; B. Add polyurethane prepolymer to the chain extender for reaction, then add acid for reaction, and stir and disperse in deionized water to obtain a cationic polyurethane waterproofing agent dispersion.

[0008] In some embodiments, in step A, the number of carbon atoms of the alkyl group of the di-long chain alkyl secondary amine is 12-18.

[0009] In some embodiments, in step A, the reaction temperature is 60-100° C., and the reaction time is 0.5-4 h.

[0010] In some embodiments, in step A, the molar ratio of glycidol to di-long chain alkyl secondary amine is 1:1.

[0011] In some embodiments, in step B, the specific reaction process is as follows: add a polyurethane prepolymer and a solvent to a chain extender, react at 70-100°C for 1-4 hours, then cool to 40-60°C, add an acid, and neutralize for 10-30 minutes, and disperse the reaction product in deionized water under stirring conditions of 1000-2000 rpm, and stir for 10-60 minutes to obtain a cationic polyurethane waterproofing agent dispersion.

[0012] In some embodiments, the solvent includes at least one of acetone, N,N-dimethylformamide, and N-methylpyrrolidone.

[0013] In some embodiments, the acid comprises at least one of formic acid and acetic acid.

[0014] In some embodiments, the polyurethane prepolymer is prepared by the following method: A polymer polyol with a molecular weight of 1000-3000 and a dihydroxy silicone oil with a molecular weight of 500-3000 are taken, and dehydration treatment is carried out at -0.09 MPa and 120°C for 1-2 h. After dehydration, the temperature is lowered to 70-95°C, isocyanate and di-n-butyltin dilaurate are added, and the reaction is carried out for 2-4 h to obtain a polyurethane prepolymer, wherein the R value of the polyurethane prepolymer is 2.0-3.0, and the mass fraction of the dihydroxy silicone oil in the polyurethane prepolymer is 20-40%.

[0015] The present invention has the following beneficial effects: The glycidol molecule of the present invention contains both hydroxyl groups and epoxy groups. By utilizing the ring-opening reaction between the epoxy groups and the secondary amino groups in the di-long-chain alkylamine, the hydrophobic long-chain alkyl group can be introduced into the molecular structure of the glycidol. At the same time, the dihydroxy structure generated by the ring-opening reaction enables it to be used as a chain extender in the preparation process of polyurethane.

[0016] Glycidol molecules contain both hydroxyl and epoxy groups. By utilizing the ring-opening reaction between epoxy groups and secondary amino groups in di-long-chain alkylamines, hydrophobic long-chain alkyl groups can be introduced into the molecular structure of glycidol. At the same time, the dihydroxy structure generated by the ring-opening reaction allows it to be used as a chain extender in the preparation of polyurethane. The specific reaction equation is as follows:

[0017] The chain extender prepared as above can react with the isocyanate group of the prepolymer to extend the chain, thereby increasing the molecular weight of the prepolymer and introducing the long-chain alkyl side chain into the molecular structure of the polyurethane. At the same time, the generated tertiary amine group reacts with the acid to neutralize, thereby generating a quaternary ammonium salt structure on the molecular chain, which ensures that the product is soluble in water and gives it cationicity.

[0018] Unlike conventional cationic waterproofing agent emulsions which require the addition of a large amount of cationic and nonionic emulsifiers during the preparation process, the cationic waterproofing agent dispersion prepared by the present invention does not use small molecule emulsifiers during the preparation process. It utilizes acid to neutralize the tertiary amino groups on the polyurethane prepolymer to form an ionizable quaternary ammonium salt, which not only imparts cationic properties but also ensures that it can be stably dispersed in water.

[0019] Therefore, the cationic waterproofing agent dispersion prepared by the present invention eliminates the foaming problem caused by the introduction of a large amount of emulsifiers in the use of conventional waterproofing agent emulsions, and also avoids the negative impact of small molecule emulsifiers on the waterproofing effect caused by the enrichment of the film surface. In addition, during the polyurethane film formation process, the enrichment and crystallization of long-chain alkyl side chains on the surface can effectively reduce the surface energy and achieve excellent waterproofing effect. DETAILED DESCRIPTION

[0020] The technical solutions in some embodiments of the present disclosure are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0021] Example 1

[0022] First, 100 g of dehydrated polypropylene glycol with a molecular weight of 1000 and 40 g of dihydroxy silicone oil with a molecular weight of 2000 were added to a reaction bottle, and then 66.7 g of isophorone diisocyanate and 0.01 g of di-n-butyltin dilaurate were added, and the mixture was stirred and reacted at 85 °C for 3 h to obtain a polyurethane prepolymer; 7.4 g of dehydrated glycidol and 35.4 g of didodecylamine were heated to 60 °C and stirred for 2 h, and then the above polyurethane prepolymer and 30 g of acetone were added, and the mixture was reacted at 80 °C for 4 h, then cooled to 50 °C, 4.6 g of formic acid was added, and the mixture was reacted for 30 min. Under the condition of a stirring speed of 1000 r / min, 500 g of deionized water was added, and the mixture was emulsified for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0023] Example 2

[0024] First, 160 g of dehydrated polycaprolactone diol with a molecular weight of 2000 and 60 g of dihydroxy silicone oil with a molecular weight of 2000 were added to a reaction bottle, and then 66.7 g of isophorone diisocyanate and 0.01 g of di-n-butyltin dilaurate were added, and the mixture was stirred and reacted at 85 °C for 3 h to obtain a polyurethane prepolymer; 8.9 g of dehydrated glycidol and 49.2 g of ditetradecylamine were heated to 70 °C and stirred for 2 h, and then the above polyurethane prepolymer and 35 g of acetone were added, and the mixture was reacted at 80 °C for 4 h, then cooled to 50 °C, 5.5 g of formic acid was added, and the mixture was reacted for 30 min. Under the condition of stirring speed of 1500 r / min, 650 g of deionized water was added, and the mixture was emulsified for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0025] Example 3

[0026] First, 150 g of dehydrated polypropylene glycol with a molecular weight of 2000 and 50 g of dihydroxy silicone oil with a molecular weight of 1500 were added to a reaction bottle, and then 66.6 g of isophorone diisocyanate and 0.01 g of di-n-butyltin dilaurate were added, and the mixture was stirred and reacted at 85 °C for 3 h to obtain a polyurethane prepolymer; 9.6 g of dehydrated glycidol and 60.6 g of dihexadecylamine were heated to 70 °C and stirred for 2 h, and then the above polyurethane prepolymer and 40 g of N,N-dimethylformamide were added, and the mixture was reacted at 80 °C for 4 h, then cooled to 50 °C, 7.8 g of acetic acid was added, and the mixture was reacted for 30 min. Under the condition of stirring speed of 1500 r / min, 660 g of deionized water was added, and the mixture was emulsified for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0027] Example 4

[0028] First, 120 g of dehydrated polycarbonate diol with a molecular weight of 1000 and 40 g of dihydroxy silicone oil with a molecular weight of 2500 were added to a reaction bottle, and then 78.7 g of 4,4'-dicyclohexylmethane diisocyanate and 0.01 g of di-n-butyltin dilaurate were added, and the mixture was stirred and reacted at 85 °C for 3 h to obtain a polyurethane prepolymer; 10.4 g of glycidol and 73.1 g of dioctadecylamine that had been dehydrated were heated to 70 °C and stirred for 2 h, and then the above polyurethane prepolymer and 35 g of N-methylpyrrolidone were added, and the mixture was reacted at 80 °C for 4 h, then cooled to 50 °C, 8.4 g of acetic acid was added, and the mixture was reacted for 30 min. Under the condition of stirring speed of 2000 r / min, 600 g of deionized water was added, and the mixture was emulsified for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0029] Application detection (1) Determination of zeta potential of dispersion: The above Examples 1 to 4 were diluted with deionized water to an effective solid content of 1%, and then measured using a Zetasizer Nano S90 laser particle size-potential analyzer.

[0030] Zeta potential measurement results: sample Example 1 Example 2 Example 3 Example 4 Zeta potential 29.34mv 28.23mv 27.85mv 30.28mv

[0031] The zeta potentials of the dispersions of Examples 1 to 4 are all positive, indicating that they are all cationic dispersions.

[0032] (2) Determination of waterproof performance: The above Examples 1 to 4 were diluted with deionized water to an effective solid content of 1%, and the padding process was used, specifically: one dip and one padding (pressure 2 kg / cm 2 )→Drying (100 ℃)→Bake in a setting machine (cotton: 160 ℃ x 1.5 min; polyester-cotton 180 ℃ x 1.5 min)→Test the waterproof effect after moisture regain. Waterproof grade test according to GB / T 4745-1997 standard: Level 0: Both sides of the fabric are wetted Level 1: Almost all of the front side is wetted Level 2: More than half of the positive surface is wetted Level 3: Only a small amount of discontinuous parts on the front are wetted Level 4: The front side is not wetted but a small amount of droplets adhere to it Level 5: The front side is not wetted and no droplets adhere to it Waterproof performance test results of the embodiment 65 / 35 polyester-cotton woven fabric Cotton gauze cloth Example 1 Level 4 Level 4 Example 2 Level 4 Level 4 Example 3 Level 4~5 Level 4~5 Example 4 Level 4~5 Level 4~5

[0033] The above tests show that Examples 1 to 4 all have good waterproof effects.

[0034] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0035] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a cationic polyurethane waterproofing agent dispersion, characterized in that: The following steps are involved: A. reacting glycidol with a di-long chain alkyl secondary amine to obtain a chain extender; B. Add polyurethane prepolymer to the chain extender for reaction, then add acid for reaction, and stir and disperse in deionized water to obtain a cationic polyurethane waterproofing agent dispersion.

2. The preparation method according to claim 1, characterized in that: In step A, the number of carbon atoms of the alkyl group of the di-long chain alkyl secondary amine is 12-18.

3. The preparation method according to claim 1, characterized in that: In step A, the reaction temperature is 60-100° C., and the reaction time is 0.5-4 h.

4. The preparation method according to claim 1, characterized in that: In step A, the molar ratio of glycidol to di-long chain alkyl secondary amine is 1:

1.

5. The preparation method according to claim 1, characterized in that: In step B, the specific reaction process is as follows: add the polyurethane prepolymer and the solvent to the chain extender, react at 70-100° C. for 1-4 hours, then cool to 40-60° C., add acid, neutralize for 10-30 minutes, and disperse the reaction product in deionized water under stirring conditions of 1000-2000 rpm, stir for 10-60 minutes, and obtain a cationic polyurethane waterproofing agent dispersion.

6. The preparation method according to claim 5, characterized in that: The solvent includes at least one of acetone, N,N-dimethylformamide and N-methylpyrrolidone.

7. The preparation method according to claim 5, characterized in that: The acid includes at least one of formic acid and acetic acid.

8. The preparation method according to claim 5, characterized in that: The preparation of the polyurethane prepolymer adopts the following method: A polymer polyol with a molecular weight of 1000-3000 and a dihydroxy silicone oil with a molecular weight of 500-3000 are taken, and dehydrated at -0.09MPa and 120°C for 1-2 h. After dehydration, the temperature is lowered to 70-95°C, isocyanate and di-n-butyltin dilaurate are added, and the reaction is carried out for 2-4 h to obtain a polyurethane prepolymer, wherein the R value of the polyurethane prepolymer is 2.0-3.0, and the mass fraction of the dihydroxy silicone oil in the polyurethane prepolymer is 20-40%.

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