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CN-122011322-A - Low-swelling aqueous polyurethane and preparation method thereof

CN122011322ACN 122011322 ACN122011322 ACN 122011322ACN-122011322-A

Abstract

The invention relates to the technical field of waterborne polyurethane, in particular to low-swelling waterborne polyurethane and a preparation method thereof. The preparation method comprises the following steps of S1, mixing polyalcohol, curing agent and catalyst to perform polymerization reaction to generate prepolymer, S2, adding hydrophilic chain extender and organic solvent to the prepolymer to perform reaction to generate hydrophilic polymer solution, S3, cooling the hydrophilic polymer solution, adding water solution of neutralizing agent to perform neutralization reaction, adding water to obtain mixed solution, and S4, adding water solution of cross-linking agent to the mixed solution to perform stirring reaction, and removing the organic solvent to obtain the low-swelling waterborne polyurethane. The prepared waterborne polyurethane has excellent solvent resistance through a specific preparation process and a specific amount of raw materials, and particularly has lower swelling rate in an ester solvent.

Inventors

  • XIONG GUIYU
  • Han Chimin

Assignees

  • 有行鲨鱼（上海）科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260303

Claims (10)

  1. 1. The preparation method of the low-swelling aqueous polyurethane is characterized by at least comprising the following steps: s1, mixing polyalcohol, a curing agent and a catalyst for polymerization reaction to generate a prepolymer; s2, adding a hydrophilic chain extender and an organic solvent into the prepolymer to react to generate a hydrophilic polymer solution; s3, cooling the hydrophilic polymer solution, adding an aqueous solution of a neutralizing agent for neutralization reaction, and adding water for dispersion to obtain a mixed solution; S4, adding an aqueous solution of a cross-linking agent into the mixed solution, stirring and reacting, and removing the organic solvent to obtain the low-swelling aqueous polyurethane; the mass of the organic solvent is 100% -140% based on 100% of the total mass of the polyol, the curing agent, the hydrophilic chain extender, the crosslinking agent and the neutralizing agent; The amount of the cross-linking agent is 0.1-1.9% of the mass of the polyol.
  2. 2. The process according to claim 1, wherein the polymerization reaction in S1 is carried out at a reaction temperature of 80 to 90℃for a reaction time of 2 to 4 hours.
  3. 3. The process according to claim 1, wherein the reaction conditions in S2 are a reaction temperature of 65-75deg.C and a reaction time of 16-18h.
  4. 4. The method according to claim 1, wherein the temperature of cooling in S3 is 30 ℃.
  5. 5. The preparation method according to claim 1, wherein the mass ratio of the neutralizing agent to water in the aqueous solution of the neutralizing agent is 1 (15-25).
  6. 6. The method of claim 1, wherein the amount of neutralizing agent species in the aqueous neutralizing agent solution is 80% to 100% of the amount of hydrophilic chain extender species.
  7. 7. The method according to claim 1, wherein the mass of the hydrophilic chain extender is 3.9% to 10% based on 100% of the total mass of the polyol, the curing agent, the hydrophilic chain extender, the crosslinking agent and the neutralizing agent.
  8. 8. The method according to claim 1, wherein the catalyst is used in an amount of 800ppm or less based on 100% by mass of the total of the hydrophilic chain extender, the polyol and the curing agent.
  9. 9. The method according to claim 1, wherein the mass of the curing agent is 18.9 to 29% based on 100% of the total mass of the polyol, the curing agent, the hydrophilic chain extender, the crosslinking agent and the neutralizing agent.
  10. 10. A low swelling aqueous polyurethane prepared by the preparation method of any one of claims 1 to 9.

Description

Low-swelling aqueous polyurethane and preparation method thereof Technical Field The invention relates to the technical field of waterborne polyurethane, in particular to low-swelling waterborne polyurethane and a preparation method thereof. Background Polyurethane is a polymer with carbamate groups on a high molecular main chain, has excellent flexibility, strong aging resistance, adjustable hardness, low-temperature deflection resistance and comprehensive characteristics superior to those of many other materials. At present, it has been widely used in the fields of paint, elastomer, foam and the like. In recent years, with the progress of technology, demands for material properties are continuously increasing, contradiction between low performance and high demands is increasingly prominent, and thus development of high performance and functional materials is becoming more important and urgent. Meanwhile, along with the improvement of environmental protection standards, the development of environmental protection materials is also becoming more critical. The aqueous polyurethane is prepared by taking water as a dispersion medium in the polyurethane, has the characteristics of incombustibility, low VOC, safety, environmental protection and the like, and can be widely applied to various fields of industry. The Chinese patent application CN106496514A prepares the aqueous polyurethane by taking polyester polyol and polyether polyol as main chains, but adopts polycarbonate polyol, polyester polyol and polyether polyol as main chains, and has extremely poor ester solvent resistance and extremely easy bonding failure caused by swelling and dissolution due to the similar principle of compatibility. Disclosure of Invention In order to solve the problem of solvent resistance of the aqueous polyurethane, particularly the carbonate solvent, the first aspect of the invention provides a preparation method of the low-swelling aqueous polyurethane, which at least comprises the following steps: s1, mixing polyalcohol, a curing agent and a catalyst for polymerization reaction to generate a prepolymer; s2, adding a hydrophilic chain extender and an organic solvent into the prepolymer to react to generate a hydrophilic polymer solution; s3, cooling the hydrophilic polymer solution, adding an aqueous solution of a neutralizing agent for neutralization reaction, and adding water for dispersion to obtain a mixed solution; S4, adding an aqueous solution of a cross-linking agent into the mixed solution, stirring and reacting, and removing the organic solvent to obtain the low-swelling aqueous polyurethane; the mass of the organic solvent is 100% -140% based on 100% of the total mass of the polyol, the curing agent, the hydrophilic chain extender, the crosslinking agent and the neutralizing agent; The amount of the cross-linking agent is 0.1-1.9% of the mass of the polyol. In some embodiments, the crosslinker may be used in an amount of 0.1%, 0.5%, 1%, 1.9%, or any value in the range of 0.1% to 1.9%. In the conventional preparation process of the aqueous polyurethane, raw materials such as polyol, a curing agent, a chain extender, a catalyst and the like are generally added into a reaction system at one time, and then the reaction is carried out under certain conditions. The process is simple to operate, but has the defects of poor reaction selectivity, uneven chain segment structure, uneven cross-linking structure and poor solvent resistance. The invention creatively adopts a step polymerization mode, firstly, polyol resin, polyisocyanate curing agent and catalyst react to generate prepolymer, and at the moment, the hard segment structure of polyurethane is mainly formed. Then adding hydrophilic chain extender and solvent into the prepolymer for further reaction. This stepwise addition ensures that the hydrophilic chain extender is uniformly distributed in the prepolymer to form a uniform polarity distribution. The uniform polarity distribution ensures that the polarity of the whole chain segment is more consistent and is not easy to permeate by the ester solvent, thereby remarkably reducing swelling. On the other hand, the amount of the organic solvent and the crosslinking agent used in the preparation of the aqueous polyurethane has a critical influence on the performance of the aqueous polyurethane. If the consumption of the organic solvent is too small, the viscosity is rapidly increased in the polymerization process, so that the reaction degree of isocyanate and active hydrogen is reduced, the molecular weight of the polymer is lower, the swelling rate is increased, the total concentration of active groups is reduced, the reaction degree is insufficient, the molecular weight is lower, and the swelling rate is increased. In the invention, the mass of the organic solvent is controlled to be 100% -140% based on 100% of the total mass of the polyol, the curing agent, the hydrophilic chain extender, the crosslinking agent and the