阅读说明：本技术 一种无溶剂封闭型聚氨酯交联剂及其制备方法 (Solvent-free blocked polyurethane cross-linking agent and preparation method thereof ) 是由 许志军 梁永标 张世恒 黄尚东 于 2020-07-24 设计创作，主要内容包括：本发明涉及一种无溶剂封闭型的聚氨酯交联剂分散体的制备,其可用于织物表面的防水整理。本发明采用季戊四醇与异氰酸酯反应,得到多官能度的端异氰酸酯低聚物,然后用加入封闭剂进行封闭反应,同单乙醇胺反应,加酸中和,最后加水分散乳化,得到一种不需要添加溶剂,具有多官能度的封闭型水性聚氨酯交联剂。本发明的聚氨酯分散体,其乳液具有良好的稳定性能；应用时通过提高工艺中焙烘温度,使封闭剂发生解封反应,裸露出的异氰酸酯基可连接织物与防水剂,从而提高织物表面的防水牢度,同时不影响织物的手感。(The invention relates to a preparation method of solvent-free blocked polyurethane cross-linking agent dispersion, which can be used for waterproof finishing of fabric surfaces. The invention adopts pentaerythritol to react with isocyanate to obtain a multifunctional end isocyanate oligomer, then a blocking agent is added to carry out blocking reaction, the end isocyanate oligomer reacts with monoethanolamine, acid is added to neutralize, and finally water is added to disperse and emulsify to obtain the blocking type waterborne polyurethane crosslinking agent which does not need to add a solvent and has multiple functions. The emulsion of the polyurethane dispersion has good stability; when the method is used, the sealing agent is subjected to deblocking reaction by increasing the baking temperature in the process, and the exposed isocyanate group can connect the fabric and the waterproof agent, so that the waterproof fastness of the fabric surface is improved, and the hand feeling of the fabric is not influenced.)

1. A solvent-free closed polyurethane cross-linking agent is characterized in that the structural formula is as follows,

wherein R represents a diisocyanate; x represents a blocking agent.

2. The method for preparing the solvent-free blocked polyurethane crosslinking agent according to claim 1, wherein: synthesizing multifunctional end isocyanate oligomer by adopting pentaerythritol and isocyanate, then adding a sealing agent to carry out sealing reaction, then reacting with monoethanolamine, adding acid to neutralize, and finally adding water to disperse and emulsify to obtain the sealed waterborne polyurethane crosslinking agent.

3. The method for preparing the solvent-free blocked polyurethane crosslinking agent according to claim 2, comprising the steps of:

s1) adding 1x mol of pentaerythritol and 4x mol of isocyanate into a reaction vessel, heating to 60 ℃ for reaction for 2 hours under the condition of continuous stirring and nitrogen atmosphere protection, heating to 80-85 ℃ for reaction for 3-4 hours, and adding a certain catalyst for continuous reaction for 2 hours;

s2), cooling to 50-60 ℃, adding 3x mol of sealing agent into a reaction container under the conditions of continuous stirring and nitrogen atmosphere protection, and reacting for 0.5 hour to obtain a polyurethane prepolymer terminated by-NCO;

s3) adding 1x mol of monoethanolamine into a reaction vessel, heating to 80-85 ℃ and reacting for 1-2 hours; adding 1.1x mol of monoacid for neutralization, then adding deionized water under high-speed shearing at 2000rpm, and dispersing for a certain time to obtain stable polyurethane emulsion, namely the closed polyurethane dispersion; x is a constant greater than 0.

4. The method for preparing the solvent-free blocked polyurethane crosslinking agent according to claim 3, wherein: the diisocyanate is selected from isophorone diisocyanate.

5. The method for preparing the solvent-free blocked polyurethane crosslinking agent according to claim 3, wherein: the blocking agent is selected from one or more of 3, 5-dimethylpyrazole, butanone oxime, caprolactam and N-methylaniline.

6. The method for preparing the solvent-free blocked polyurethane crosslinking agent according to claim 3, wherein: the monoacid is selected from hydrochloric acid and/or acetic acid.

Technical Field

The invention relates to the technical field of fine chemical engineering, in particular to a solvent-free enclosed polyurethane cross-linking agent and a preparation method thereof.

Background

Polyurethane resins are mainly classified into oil-based polyurethanes and water-based polyurethanes according to the kind of solvent. In recent years, with the improvement of environmental protection consciousness of consumers and the continuous upgrading of environmental protection standards, the oil-based polyurethane product contains a large amount of solvents, releases VOC during use, cannot meet the emission requirement, and is not suitable for finishing fabrics. Meanwhile, the waterborne polyurethane does not contain a solvent, and the components except the polyurethane part are water, so that the concept of a green product is met. And the polyurethane has the characteristics of good elasticity, stability, high solid content and the like, and special properties are endowed by the polyurethane through a material with high cost performance just required for fabric finishing. Therefore, the opportunities of the waterborne polyurethane for finishing the fabric are more and more, and the application field of the waterborne polyurethane is further extended.

At present, some solvent-free polyurethane crosslinking agents appear in the market, and the style characteristics are different; the blocked crosslinking agent used for fabric waterproofing has special requirements, such as improvement of fabric waterproofing fastness, no influence on fabric hand feeling or improvement of hand feeling, deblocking temperature, storage stability and the like. Therefore, around these key factors, it is of particular interest to develop a cross-linking agent suitable for the water-repellent finishing of textiles.

Disclosure of Invention

The invention aims to provide a solvent-free enclosed polyurethane cross-linking agent and a preparation method thereof, which are suitable for waterproof finishing of fabrics, have simple and convenient synthesis operation and easily obtained raw materials and overcome the defects of the prior art.

The technical scheme for solving the technical problem is as follows: a solvent-free closed polyurethane cross-linking agent, which has the following structural formula,

wherein R represents a diisocyanate; x represents a blocking agent.

The preparation method of the solvent-free blocked polyurethane crosslinking agent comprises the following steps: synthesizing multifunctional end isocyanate oligomer by adopting pentaerythritol and isocyanate, then adding a sealing agent to carry out sealing reaction, then reacting with monoethanolamine, adding acid to neutralize, and finally adding water to disperse and emulsify to obtain the sealed waterborne polyurethane crosslinking agent.

The preparation method of the solvent-free blocked polyurethane crosslinking agent comprises the following steps:

s1) adding 1x mol of pentaerythritol and 4x mol of isocyanate into a reaction vessel, heating to 60 ℃ for reaction for 2 hours under the condition of continuous stirring and nitrogen atmosphere protection, heating to 80-85 ℃ for reaction for 3-4 hours, and adding a certain catalyst for continuous reaction for 2 hours;

s2), cooling to 50-60 ℃, adding 3x mol of sealing agent into a reaction container under the conditions of continuous stirring and nitrogen atmosphere protection, and reacting for 0.5 hour to obtain a polyurethane prepolymer terminated by-NCO;

s3) adding 1x mol of monoethanolamine into a reaction vessel, heating to 80-85 ℃ and reacting for 1-2 hours; adding 1.1xmol monoacid for neutralization, then adding deionized water under high-speed shearing at 2000rpm, and dispersing for a certain time to obtain stable polyurethane emulsion, namely the closed polyurethane dispersion; x is a constant greater than 0.

The diisocyanate is selected from isophorone diisocyanate.

The blocking agent is selected from one or more of 3, 5-dimethylpyrazole, butanone oxime, caprolactam and N-methylaniline.

The monoacid is selected from hydrochloric acid and/or acetic acid.

The invention has the beneficial effects that:

compared with the prior art, the invention has the advantages that: the solvent-free polyurethane cross-linking agent dispersion has the advantages of simple structure, simple and convenient synthesis operation, easily obtained raw materials, obvious effect and environmental protection, and can be used for preparing solvent-free polyurethane cross-linking agent dispersions.

Detailed Description

The following detailed description of embodiments of the invention is intended to be illustrative, but not limiting, of the invention.