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What is the main purpose of the polyurethane catalyst?
Edit:Nantong Yutai Chemical Products Co., Ltd.   UpDate:2019-10-11

A study on polyurethane catalysts mentions that the reaction of isocyanate with a polyol is called gelation and eventually produces a carbamate. The reaction of isocyanate with water (called a foaming reaction) ultimately produces dolphins. When the carbamate is further reacted with isocyanate at night, crosslinking may occur, and methyl formate and crater may be produced separately. Isocyanates can be self-condensed into trimers, dimers and carbodiimides in several different ways. The choice of catalyst affects the reactivity of the overall foaming system and the selectivity of some of the individual reactions described above. The reactivity of the foaming system is indicated by the activation time of the system, the curing process, the demolding or curing time.

The most commonly used catalysts for polyurethane foaming are tertiary amines, quaternary amines, amine salts and metal nucleic acid salts (usually SnII, SnIV or K+). A tertiary amine is used to promote gelation. Foaming and crosslinking reactions. Limb salts and heat-sensitive amines, such as diazobicycloundecane, are used to provide a blocking effect. Metal salts strongly influence the gelation reaction. The stannous compound (SnII) is low in cost but easily hydrolyzed and unstable. Its typical use is to be able to meter separate streams of applications, such as soft blocks. The tin compound (SnIV) is not easily hydrolyzed and can be incorporated into systems such as soft molded and rigid foams. For example, a specific class of compounds, such as quaternary amines, potassium nucleic acids, tris(dimethylaminomethyl)phenol, and 2,4,

performance

1. A selective polyurethane gel catalyst;

2. Compared with the tin catalyst, the selectivity to the NCO group is better, and the mechanical properties of the finished product are better;

3. The induction time is short and the viscosity is gradually increased.


Advantages of organic bismuth polyurethane catalyst

1. Safe and environmentally friendly catalysts, which can replace lead-mercury catalysts and tin catalysts that are being abolished by legislation;

2. The ruthenium catalyst has better hydrolysis resistance stability than the tin catalyst, and reduces the selectivity of reaction with water. In the aqueous PU dispersion, the side reaction of water and NCO group is reduced;

3. Promote NCO/OH reaction, avoid NCO side reaction, and reduce CO2 formation;

4. Freeing the water-shielded amines in a one-component system rather than promoting the reaction of NCO with water;

5. The synergistic effect of the bismuth-zinc combination makes the formulation and production more flexible, reducing energy consumption and increasing profits;

6. Can be used alone or as an auxiliary catalyst in combination with an amine or other organometallic compound;


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