Six major characteristics of water-based polyurethane adhesives and solutions to degumming problems

Water-based polyurethane adhesive （AbbreviationPU glue）Yes Refers to adhesives made with water-based polyurethane as the base material. It is an important category of water-based adhesives. It has gained popularity in recent years due to its excellent adhesion, outstanding oil resistance, impact resistance, wear resistance, low temperature resistance and other characteristics. develop rapidly.

Water-based polyurethane

font>6 major features:

1, not included in most water-based polyurethane adhesives-NCO group, therefore, it mainly relies on the cohesion and adhesion generated by the polar groups in the molecule for curing. Solvent-based or solvent-free one-component and two-component polyurethane adhesives can make full use of the reaction of -NCO to enhance bonding performance during the bonding and curing process. Water-based polyurethane contains carboxyl, hydroxyl and other groups, which can participate in the reaction under appropriate conditions and cause cross-linking of the adhesive.

2、In addition to the additional polymer thickener, important factors affecting the viscosity of water-based polyurethane include ionic charge, core-shell structure, emulsion particle size, etc. The more ions and counterions (referring to the free ions in the solution with opposite polarity to the ionic groups contained in the polyurethane main chain and side chains) on the polymer molecules, the greater the viscosity and the solid content (concentration), polyurethane resin The molecular weight, cross-linking agent and other factors have no obvious influence on the viscosity of water-based polyurethane, which is conducive to the high molecular weight of polyurethane to improve the cohesive strength of the adhesive. In contrast, the main influencing factors of the viscosity of solvent-based polyurethane adhesives are the molecular weight of the polyurethane, the degree of branching, and the concentration of the glue. With the same solid content, the viscosity of water-based adhesives is smaller than that of solvent-based adhesives.

3、Viscosity is an important parameter for the performance of adhesives. The viscosity of water-based polyurethane is generally adjusted by water-soluble thickener and water. The solvent-based adhesive can be adjusted by increasing the solid content, the molecular weight of the polyurethane or selecting an appropriate solvent.

4、Because water is less volatile than organic solvents, water-based polyurethane adhesives dry slowly, and due to the large surface tension of water, they have poor wetting ability on surface hydrophobic substrates Difference. If most of the moisture is heated and dried before it evaporates from the adhesive layer or coating into the air, or is absorbed by the porous substrate, it will be difficult to obtain a continuous adhesive layer.

5、Water-based polyurethane adhesives can be blended with a variety of water-based resins to improve performance or reduce costs. At this time, attention should be paid to the ionic properties and acidity and alkalinity of the ionic water-based glue, otherwise it may cause aggregation. Due to compatibility between polymers or solubility in certain solvents, solvent-based polyurethane adhesives can only be blended with a limited number of other resin adhesives.

6、Water-based polyurethane adhesive has a small smell, is easy to operate, and the residual adhesive is easy to clean. However, the use of solvent-based polyurethane adhesive sometimes requires a large amount of solvent, and cleaning is not as convenient as water-based adhesive.

Water-based polyurethane adhesive degumming problem Solution:

Water-based polyurethane adhesives are widely used in the field of adhesive and flocking of automobile interiors, such as automobile…Decorated glove box, storage box, central armrest box, etc. However, in automotive interior parts, PP material is widely used. Since PP material is a non-polar material, the surface is difficult to bond, and there is often a gap between the PP substrate and the water-based polyurethane glue. There are problems such as degumming in the bonding. An effective solution is to pre-treat the surface of the PP material and apply a layer of PP treatment agent developed by Jiongsheng Treatment Agent between the substrate and the adhesive to enhance the adhesion and solve problems such as unreliable bonding and degumming. Through RoHS detection.