Preparation method of a cationic polyurethane waterproofing agent dispersion

Abstract

The present invention belongs to the technical field of fine chemical engineering, and particularly relates to a preparation method of a cationic polyurethane waterproofing agent dispersion, which comprises the following steps: A. React glycidol with a double long-chain alkyl secondary amine to obtain a chain extender; B. Add a polyurethane prepolymer to the chain extender for reaction, then add an acid for reaction, and stir and disperse in deionized water to obtain a cationic polyurethane waterproofing agent dispersion. The cationic waterproofing agent dispersion prepared by the present invention eliminates the foam problem caused by the introduction of a large amount of emulsifiers during the use of conventional waterproofing agent emulsions, and also avoids the negative impact on the waterproof effect caused by the enrichment of small molecule emulsifiers on the film surface. In addition, during the film-forming process of polyurethane, the enrichment and crystallization of long-chain alkyl side chains on the surface can effectively reduce the surface energy and achieve excellent waterproof effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of fine chemicals, and particularly relates to a preparation method of a cationic polyurethane waterproofing agent dispersion. Background Art

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

[0003] With the increasingly strict environmental protection 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 cause pollution to the environment during production and use. Currently, the fluorine-free waterproofing agents on the market are mainly cationic polyacrylate emulsions. In the preparation process of such products, long-chain alkyl (meth)acrylate and acrylate monomers with strong hydrophobicity are generally added for copolymerization, and silicone oil with low surface energy is compounded. The synergistic effect of silicone oil and long-chain alkyls enables such products to achieve good waterproof performance. However, in the preparation process of such products, cationic emulsifiers are generally used to provide stability, resulting in more foam during the use of such products, and it is easy to produce foam spots. In addition, cationic emulsifiers are prone to migrate to the surface during the film-forming process, and the enrichment of hydrophilic groups on the surface will also have a negative impact on the waterproof effect.

[0004] In the preparation of aqueous polyurethane, no emulsifier needs to be added, and stability is achieved by the self-emulsification of hydrophilic groups on the molecular chain. Therefore, using aqueous polyurethane as a waterproofing agent can effectively avoid the problems of foam and the enrichment of surfactants on the film-forming surface of traditional acrylate waterproofing agents, and by utilizing the excellent film-forming physical properties of polyurethane, the application effect of the waterproofing agent can be effectively enhanced. In the preparation process of aqueous polyurethane-based waterproofing agents, although the reaction of hydroxyl silicone oil with isocyanate groups can effectively introduce organosiloxane into the polyurethane molecular chain and improve the waterproof performance 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 determining the waterproof performance. At present, in the preparation process of aqueous polyurethane, there is a lack of a method to introduce long-chain alkyls into the polyurethane side chain, resulting in poor waterproof effect of polyurethane-based waterproofing agents.

[0005] In view of the above problems, there is an urgent need in the market to improve the existing polyurethane-based waterproofing agents to overcome the existing defects. Summary of the Invention

[0006] 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:

[0008] An embodiment of the present application provides a method for preparing a cationic polyurethane waterproofing agent dispersion, comprising the following steps:

[0009] A. React glycidyl with a double long-chain alkyl secondary amine to obtain a chain extender;

[0010] B. Add a polyurethane prepolymer to the chain extender for reaction, then add an acid for reaction, and stir and disperse in deionized water to obtain a cationic polyurethane waterproofing agent dispersion.

[0011] In some embodiments, in step A, the alkyl carbon atoms of the double long-chain alkyl secondary amine are 12-18.

[0012] In some embodiments, in step A, the reaction temperature is 60-100 °C and the reaction time is 0.5-4 h.

[0013] In some embodiments, in step A, the molar ratio of glycidyl to the double long-chain alkyl secondary amine is 1:1.

[0014] In some embodiments, in step B, the specific reaction process is as follows: Add a polyurethane prepolymer and a solvent to the chain extender, react at 70-100 °C for 1-4 h, then cool down to 40-60 °C, add an acid, carry out a neutralization reaction for 10-30 min, and under the stirring condition of 1000-2000 rpm, disperse the reaction product in deionized water and stir for 10-60 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0015] In some embodiments, the solvent includes at least one of acetone, N,N-dimethylformamide, and N-methylpyrrolidone.

[0016] In some embodiments, the acid includes at least one of formic acid and acetic acid.

[0017] In some embodiments, the polyurethane prepolymer is prepared by the following method:

[0018] Take polymer polyol with a molecular weight of 1000 - 3000 and dihydroxy silicone oil with a molecular weight of 500 - 3000, and conduct dehydration treatment at -0.09 MPa and a temperature of 120 °C for 1 - 2 h. After the dehydration is completed, cool down to 70 - 95 °C, add isocyanate and dibutyltin dilaurate, and react for 2 - 4 h to obtain a polyurethane prepolymer. 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%.

[0019] The present invention has the following beneficial effects:

[0020] In the glycidol molecule of the present invention, there are both hydroxyl groups and epoxy groups. By using the ring-opening reaction of the epoxy group with the secondary amino group in the bis-long-chain alkylamine, a hydrophobic long-chain alkyl group can be introduced into the molecular structure of glycidol. At the same time, the dihydroxy structure formed by the ring-opening reaction enables it to be used as a chain extender in the preparation of polyurethane.

[0021] In the glycidol molecule, there are both hydroxyl groups and epoxy groups. By using the ring-opening reaction of the epoxy group with the secondary amino group in the bis-long-chain alkylamine, a hydrophobic long-chain alkyl group can be introduced into the molecular structure of glycidol. At the same time, the dihydroxy structure formed by the ring-opening reaction enables it to be used as a chain extender in the preparation of polyurethane. The specific reaction equation is as follows:

[0022]

[0023] The above-prepared chain extender can carry out a chain extension reaction with the isocyanate group of the prepolymer. While increasing the molecular weight of the prepolymer, a long-chain alkyl side chain is introduced into the molecular structure of the polyurethane. At the same time, the generated tertiary amine group undergoes a neutralization reaction with an acid, thereby generating a quaternary ammonium salt structure on the molecular chain, endowing it with cationicity while ensuring the product is soluble in water.

[0024] Different from the conventional cationic waterproofing agent emulsion that requires adding a large amount of cationic and non-ionic emulsifiers during the preparation process, the cationic waterproofing agent dispersion prepared in the present invention does not use small-molecule emulsifiers during the preparation process. It uses an acid to neutralize the tertiary amino group on the polyurethane prepolymer to form an ionizable quaternary ammonium salt, which not only endows it with cationicity but also ensures its stable dispersion in water.

[0025] Therefore, the cationic waterproofing agent dispersion prepared in the present invention eliminates the foam problem caused by the introduction of a large amount of emulsifiers during the use of the conventional waterproofing agent emulsion, and also avoids the negative impact on the waterproof effect caused by the enrichment of small-molecule emulsifiers on the film surface. In addition, during the film-forming process of polyurethane, the enrichment and crystallization of the long-chain alkyl side chains on the surface can effectively reduce the surface energy and achieve excellent waterproof effects. Specific embodiments

[0026] The technical solutions in some embodiments of the present disclosure will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments provided by the present disclosure belong to the scope of protection of the present disclosure.

[0027] Example 1

[0028] First, 100 g of polypropylene glycol with a molecular weight of 1000 and 40 g of dihydroxy silicone oil with a molecular weight of 2000 that have been dehydrated are added to a reaction flask. Then, 66.7 g of isophorone diisocyanate and 0.01 g of dibutyltin dilaurate are added, and the mixture is stirred and reacted at 85 °C for 3 h to obtain a polyurethane prepolymer; 7.4 g of glycidol and 35.4 g of didodecylamine that have been dehydrated are heated to 60 °C, stirred and reacted for 2 h. Subsequently, the above polyurethane prepolymer and 30 g of acetone are added, and the reaction is carried out at 80 °C for 4 h. Then, the temperature is lowered to 50 °C, 4.6 g of formic acid is added, and the reaction is carried out for 30 min. Under the condition that the stirring speed is 1000 r / min, 500 g of deionized water is added and emulsified for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0029] Example 2

[0030] First, 160 g of polycaprolactone diol with a molecular weight of 2000 and 60 g of dihydroxy silicone oil with a molecular weight of 2000 that have been dehydrated are added to a reaction flask. Then, 66.7 g of isophorone diisocyanate and 0.01 g of dibutyltin dilaurate are added, and the mixture is stirred and reacted at 85 °C for 3 h to obtain a polyurethane prepolymer; 8.9 g of glycidol and 49.2 g of ditetradecylamine that have been dehydrated are heated to 70 °C, stirred and reacted for 2 h. Subsequently, the above polyurethane prepolymer and 35 g of acetone are added, and the reaction is carried out at 80 °C for 4 h. Then, the temperature is lowered to 50 °C, 5.5 g of formic acid is added, and the reaction is carried out for 30 min. Under the condition that the stirring speed is 1500 r / min, 650 g of deionized water is added and emulsified for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0031] Example 3

[0032] First, add 150 g of polypropylene glycol with a molecular weight of 2000 and 50 g of dihydroxy silicone oil with a molecular weight of 1500, which have been dehydrated, into a reaction flask. Then, add 66.6 g of isophorone diisocyanate and 0.01 g of dibutyltin dilaurate, and stir and react at 85 °C for 3 h to obtain a polyurethane prepolymer; dehydrate 9.6 g of glycidol and 60.6 g of dihexadecylamine, heat up to 70 °C, stir and react for 2 h. Subsequently, add the above polyurethane prepolymer and 40 g of N,N-dimethylformamide, react at 80 °C for 4 h, then cool down to 50 °C, add 7.8 g of acetic acid, react for 30 min, and under the condition of a stirring speed of 1500 r / min, add 660 g of deionized water and emulsify for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0033] Example 4

[0034] First, add 120 g of polycarbonate diol with a molecular weight of 1000 and 40 g of dihydroxy silicone oil with a molecular weight of 2500, which have been dehydrated, into a reaction flask. Then, add 78.7 g of 4,4'-dicyclohexylmethane diisocyanate and 0.01 g of dibutyltin dilaurate, and stir and react at 85 °C for 3 h to obtain a polyurethane prepolymer; dehydrate 10.4 g of glycidol and 73.1 g of dioctadecylamine, heat up to 70 °C, stir and react for 2 h. Subsequently, add the above polyurethane prepolymer and 35 g of N-methylpyrrolidone, react at 80 °C for 4 h, then cool down to 50 °C, add 8.4 g of acetic acid, react for 30 min, and under the condition of a stirring speed of 2000 r / min, add 600 g of deionized water and emulsify for 20 min to obtain a cationic polyurethane waterproofing agent dispersion.

[0035] Application detection

[0036] (1) Determination of the ξ potential of the dispersion: First, dilute the above Examples 1 to 4 with deionized water to an effective solid content of 1%, and then measure with a Zetasizer Nano S90 laser particle size - potential analyzer.

[0037] Results of ξ potential determination:

[0038] Sample Example 1 Example 2 Example 3 Example 4 Zeta potential 29.34 mV 28.23 mV 27.85 mV 30.28 mV

[0039] The ξ potentials of the dispersions in Examples 1 to 4 are all positive, indicating that they are all cationic dispersions.

[0040] (2) Determination of waterproof performance: First, dilute the above Examples 1 to 4 with deionized water to an effective solid content of 1%, and adopt the padding process, specifically: one dip and one pad (pressure 2 kg / cm 2) → Drying (100 °C) → Curing in a stenter (cotton: 160 °C x 1.5 min; polyester-cotton: 180 °C x 1.5 min) → Measuring the waterproof effect after moisture regain. The waterproof grade test is carried out according to the standard of GB / T 4745-1997:

[0041] Grade 0: Both the front and back sides of the fabric are wetted.

[0042] Grade 1: Almost the entire front side is wetted.

[0043] Grade 2: More than half of the front surface is wetted.

[0044] Grade 3: Only a small amount of discontinuous parts on the front side are wetted.

[0045] Grade 4: The front side is not wetted but there are a small number of liquid droplets adhering.

[0046] Grade 5: The front side is not wetted and there are no liquid droplets adhering.

[0047] Test results of the waterproof performance of the examples

[0048] 65 / 35 polyester-cotton shuttle fabric Pure cotton yarn drill fabric Example 1 Grade 4 Grade 4 Example 2 Grade 4 Grade 4 Example 3 Grade 4 - Grade 5 Grade 4 - Grade 5 Example 4 Grade 4 - Grade 5 Grade 4 - Grade 5

[0049] The above tests show that Examples 1 to 4 all have good waterproof effects.

[0050] In the description of this specification, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0051] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claimed rights.

Claims

1. A preparation method of a cationic polyurethane waterproofing agent dispersion, characterized in that, It includes the following steps: A. React glycidol with a double long-chain alkyl secondary amine to obtain a chain extender; B. Add a polyurethane prepolymer to the chain extender for reaction, then add an acid for reaction, and stir and disperse it in deionized water to obtain a cationic polyurethane waterproofing agent dispersion; In step A, the alkyl carbon atom number of the double long-chain alkyl secondary amine is 12 - 18, and the molar ratio of glycidol to the double long-chain alkyl secondary amine is 1:1; The polyurethane prepolymer is prepared by the following method: Take a polymer polyol with a molecular weight of 1000 - 3000 and a dihydroxy silicone oil with a molecular weight of 500 - 3000, and conduct dehydration treatment at -0.09 MPa and a temperature of 120 °C for 1 - 2 h. After the dehydration is completed, cool down to 70 - 95 °C, add an isocyanate and dibutyltin dilaurate, and react for 2 - 4 h to obtain the polyurethane prepolymer. 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%; The polymer polyol is polypropylene glycol with a molecular weight of 1000, polycaprolactone diol with a molecular weight of 2000, polypropylene glycol with a molecular weight of 2000, or polycarbonate diol with a molecular weight of 1000.

2. 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.

3. 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 a solvent to the chain extender, react at 70 - 100 °C for 1 - 4 h, then cool down to 40 - 60 °C, add an acid, conduct a neutralization reaction for 10 - 30 min, and under the stirring condition of 1000 - 2000 rpm, disperse the reaction product in deionized water and stir for 10 - 60 min to obtain the cationic polyurethane waterproofing agent dispersion.

4. The preparation method according to claim 3, characterized in that, The solvent includes at least one of acetone, N,N-dimethylformamide, and N-methylpyrrolidone.

5. The preparation method according to claim 3, characterized in that, The acid includes at least one of formic acid and acetic acid.

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