Dehydration and Defoamer for Polyurethane Adhesives
In the preparation and use of polyurethane adhesives and sealants, the generation of bubbles is a common and challenging problem. The root cause lies primarily in the presence of trace amounts of moisture in the raw materials (such as polyols and solvents) or the environment. The core reaction of polyurethane is the polymerization of isocyanate (-NCO) and hydroxyl groups (-OH), but the -NCO groups can also react with water, producing carbon dioxide gas. These carbon dioxide bubbles trapped inside the adhesive are the direct source of the problem.
The presence of bubbles leads to a series of adverse consequences: First, it forms voids and defects within the cured adhesive layer, significantly reducing its mechanical strength, sealing performance, and durability. Second, surface bubbles affect the smoothness and gloss of the product's appearance, which is particularly detrimental in coating or optical applications. In severe cases, dense bubbles can even lead to direct product scrapping, resulting in raw material waste and production losses.
Activated Molecular Sieve Powder Solution
During the polyurethane mixing process, activated molecular sieve powder, with its large specific surface area and strong adsorption capacity, can preemptively and quickly capture and firmly lock in trace amounts of moisture (including moisture introduced from the air) in the system. This effectively "isolates" moisture, preventing it from contacting isocyanate (-NCO), thus fundamentally eliminating the pathway for carbon dioxide bubbles to form through the water-NCO reaction.
PM molecular sieve powder is made from molecular sieve synthetic powder with special additives through high-temperature calcination. It has extremely high specific surface area and water absorption capacity, excellent dispersibility, and rapid adsorption performance. This reduces moisture content, eliminates bubbles, and improves the uniformity and strength of materials. Furthermore, its process is simple; only 3%~5% powder molecular sieve needs to be added according to the colloid's moisture content. Its nanoscale pores precisely adsorb water molecules! After use, the measured moisture content decreased from 0.3% to below 0.01%, solving the problem of moisture and bubbles in polyurethane adhesives!
