The polyurethane delay catalyst isPolyurethane catalystA very special type of catalyst. This type of catalyst can provide the catalytic activity required for polyurethane maturation, while also extending the service life of the product and providing more operations for construction. time.
Unlike inhibitors, polyurethane delay catalysts are relatively delayed rather than absolutely delayed. Compared with conventional catalysts, the activity in the front stage is low, the overall activity is equivalent, and it cannot It plays the role of delaying the reaction in the system without adding catalyst.
According to different uses, we divide delayed catalysts into two categories: delayed catalysts for foam plastics; delayed catalysts for CASE (CASE means polyurethane coatings, polyurethane seals agents, polyurethane adhesives and polyurethane elastomers).
1. Delayed catalyst for foam
Polyurethane foam includes polyurethane hard foam, soft foam, semi-rigid foam, and self-made foam. For products such as crusting, the main reactions involved include foaming reaction, gel reaction, trimerization reaction, etc. Therefore, commonly used catalysts for polyurethane foams are mainly divided into two types: delayed foaming catalysts and delayed gelling catalysts.
The commonly used delayed foaming catalyst is DY-225, which is a glycol solution of modified bis(dimethylaminoethyl) ether, which can delay foaming. The milky time increases fluidity in the early stage and accelerates ripening in the later stage.
Delayed gel catalysts mainly include DY-8154 (modified triethylenediamine solution), DY-300, etc. In particular, DY-8154 is widely used in hard foam, soft foam, semi-rigid foam, self-skinning and other fields. It can also be seen in some microporous elastomer formulas.
New delayed catalysts. These products are different from common catalysts on the market. They are a type of delayed catalyst specially developed by Deyin Chemical. The main products are DY-215, etc. . It has the characteristics of low foaming efficiency, good delay effect, and strong gel effect. It can not only provide early fluidity, but also accelerate post-maturation and demolding. It can be used in combination with most catalysts and can replace organotin in some formulas to increase early fluidity without affecting later maturation.
2. Delay catalyst for CASE
Compared with the catalyst for foam, CASE The required catalyst must have the characteristics of fast gelling speed, micro-foaming or even no foaming. Common catalysts mainly include DY-12 (dibutyltin dilaurate), DY-20 (organic Bismuth), phenylmercuric acetate, etc. Therefore, the delayed catalyst used in CASE should be comparable in catalytic activity to tin-based catalysts. It is difficult to achieve the effect of mercury-based catalysts in terms of foaming efficiency, and should be as close as possible to the effect of dibutyltin dilaurate.
At the same time, the application fields of CASE are different from foam production. The raw materials and processes used are complex, the selection of polyether polyester types, the differences in isocyanates, as well as temperature and synthesis The sequence of steps will bring about huge differences in the results. Therefore, the choice of CASE products in delayingpolyurethane catalyst cannot be generalized and needs to be determined based on many factors.
