Stability Analysis of Polyurethane Catalysts

- Jun 25, 2018 -

Polyether polyols are homopolymers of terminal hydroxyl groups, and the hydrocarbon groups in the main chain are linked by ether bonds. This kind of polymer polyol is usually a product of a small molecule initiator (also called an initiator) having a simple molecular structure and a reaction of a polyol or a cyclic ether. Polyols [1] such as ethylene glycol, propylene glycol, glycerol, pentaerythritol, trimethylolpropane, sucrose or sorbitol, cyclic ethers such as ethylene oxide, propylene oxide, the former two mixtures, tetrahydrofuran Wait. Polyether polyols are generally used for the production of high-quality polyurethane flexible foams or rigid foams and elastomers. More important polyether polyols are polybutylene glycol ether polyol (PBD), polytetrahydrofuran polyol (PTMEG), polypropylene oxide polyol (PPO), polybutylene oxide polyol (PBO), and the like. Among them, PTMEG is a polymer polyol material with particularly excellent properties in the production of hydrolysis-resistant polyurethane elastomers.

There are many varieties of polyether polyols and the classification method is different. According to the characteristics of polyether polyols can be divided into four categories [2]: 1 General propylene oxide-based polyether polyols; 2 special propylene oxide-based polyether polyols, including high-activity polyether polyols, filled Polyether polyols, or even amino-terminated polyether polyols, low-unsaturation polyether polyols, flame-retardant polyether polyols, etc.; 3 Tetrahydrofuran-based polyether polyols; 4 Butadiene-based polyether polyols alcohol.

Nathalie Samson, Françoise Mechin, Jean-Pierre Pascault [23] (1998) used H12MDI, 4,4'-diamino-3,3'-dimethyl-dicyclohexylmethane (3DCM) and different hydrophilic, hydrazines. Soft section of water. The kinetic study of the reaction process for the synthesis of the isocyanate-terminated prepolymer shows that the use of a polymer polyol with a too low reactivity (for example, a secondary hydroxyl group-containing polyoxypropylene) increases the side reactions.

Tzong-Liu Wang, Tar-Hwa Hsieh [24] (1997) studied the thermal stability of a series of polyether polyurethanes using PEG/PPG/PTMG, MDI and ethylenediamine. The effect of soft segment molecular weight and structure on thermal stability. As a result, the thermal stability of PTMG is best, and the article attributes this to the presence or absence of urethane hydrogen bonds between molecules.

Vincent (1990) reviewed the hydrolysis, pyrolysis, oxidation, and photolysis of polyurethanes. In terms of hydrolysis stability, the mechanism of the carbodiimide structure can increase the hydrolytic stability of the polyester PU; the table is listed and the mechanism of decomposition of various groups is given; the graph indicates that at 80oC, the relative humidity is 95% Under the conditions of some of the model polymers tested, the order of the stability of the polyurethane catalyst from strong to weak is: 1PTMG-HMDI-MDA> 2PTMG-MDI-Bd> 3Polyester-MDI-Bd> 4PTMG-TDI-MBOCA> 5PPG -TDI-MBOCA > 6Polyester-TDI-MBOCA. From the above, we can see that in the soft segment and hard segment component selected above, the respective advantages and disadvantages. But still not comprehensive enough.