1、 Technical requirements for the development of waterborne polyurethane

 

Polyurethane resin is widely used in coatings, adhesives, textile coatings, and sealing materials due to its excellent mechanical properties, wear resistance, and adhesion. However, with the deepening of environmental protection concepts and the continuous improvement of performance requirements in industrial operations, traditional polyurethane resin preparation methods are facing new challenges. The preparation of polyisocyanate components in the form of aqueous dispersions has become a new direction for industry development, and the emergence of 2- (cyclohexylamine) - ethanesulfonic acid (CHES buffer) and 3- (cyclohexylamine) - propanesulfonic acid (CAPS) has injected strong impetus into this direction.

 

CHES buffer

 

2、 The structural characteristics and reaction mechanism of CHES and CAPS

 

Among various compounds containing sulfonic acid groups, 2- (cyclohexylamine) - ethanesulfonic acid (CHES) and 3- (cyclohexylamine) - propanesulfonic acid (CAPS) are suitable as hydrophilic chain extenders due to the reactive hydrogen (amino or hydroxyl) in their molecular structure that can react with isocyanate groups (- NCO).

 

Both of these compounds contain a cyclohexylamine structure and sulfonic acid groups. In the synthesis process of polyurethane, its active hydrogen participates in the polymerization reaction, fixing the sulfonic acid group on the polymer main chain to avoid the migration or loss of hydrophilic groups during use. Sulfonic acid groups can ionize in water, giving negative charges to the surface of polymer particles and improving the stability of the dispersion system through electrostatic repulsion. Compared with common carboxylic acid chain extenders (such as DMPA), sulfonic acid group has stronger hydrophilicity and wider pH adaptation range, which helps to improve the long-term storage stability of lotion.

 

3、 Performance of CHES and CAPS in practical applications

 

Introducing CHES or CAPS into actual formulas can bring the following advantages:

 

Better water dispersibility

 

The experiment shows that the use of CHES or CAPS modified polyisocyanate prepolymer in the emulsification process can form a water dispersion with smaller particle size, more uniform distribution, clear lotion appearance and good fluidity, which is conducive to subsequent processing.

 

Improve storage stability

 

The strong ionization properties of sulfonic acid groups help maintain electrostatic repulsion between particles and reduce sedimentation or viscosity increase during storage. Under normal conditions (25 ℃, dark), some systems can be stored stably for more than 6 months without obvious stratification or gel.

 

Promote curing performance

 

Due to the chemical bonding of hydrophilic groups in the main chain, after the evaporation of water during film formation, the molecular chains are more easily arranged tightly, which helps to improve the cross-linking density of the coating film. In actual testing, systems using CHES or CAPS exhibit stable performance in terms of adhesion, water resistance, and drying speed.

 

4、 The impact of raw material quality on application effectiveness

 

Despite the theoretical advantages of CHES and CAPS, their practical application effectiveness is still closely related to the purity, moisture content, and batch consistency of the raw materials. Excessive impurities or moisture may lead to premature reaction of isocyanate components, affecting the controllability of prepolymer synthesis and subsequently impacting the properties of the dispersion. Therefore, choosing raw material suppliers with high purity and stable quality is an important prerequisite for ensuring process stability and consistent product performance.

 

Product packaging

 

5、 Hubei Xindesheng: Providing stable and reliable CHES and CAPS raw materials

 

Hubei Xindesheng's CHES and CAPS products have been used in the development of water-based coatings and adhesives in multiple domestic material companies, and feedback shows that they perform well in terms of dispersibility and storage stability. At the same time, the company can also provide technical information support and provide sample testing according to customer needs.

 

If you are developing a water-based polyurethane system and hope to improve the dispersion stability and comprehensive performance of the product, please contact Hubei Xindesheng to obtain CHES and CAPS product information and technical data, and help you optimize the formula and upgrade the process.