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Stability Analysis of Polyurethane Catalysts
Edit:Nantong Yutai Chemical Products Co., Ltd.   UpDate:2019-10-11

The polyurethane catalyst is a homopolymer of terminal hydroxyl groups, and the hydrocarbon groups in the main chain are linked by an ether bond. Such polymer polyols are typically the product of the reaction of a small molecule initiator (also known as an initiator) having a simple molecular structure with a polyol or a cyclic ether. The polyol [1] such as ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, sucrose or sorbitol, a cyclic ether such as ethylene oxide, propylene oxide, the first two mixtures, tetrahydrofuran and the like. Polyether polyols are commonly used to produce high quality polyurethane flexible foams or rigid foams and elastomers. More important polyether polyols are polytetramethylene glycol ether polyol (PBD), polytetrahydrofuran polyol (PTMEG), polypropylene oxide polyol (PPO), polybutylene oxide polyol (PBO), etc. . Among them, PTMEG is a polymer polyol material having particularly excellent properties in the production of a hydrolysis-resistant polyurethane elastomer.

There are many types of polyether polyols, and the classification methods are also different. According to the characteristics of polyether polyols, it can be divided into four categories [2]: 1 general-purpose propylene oxide-based polyether polyol; two special propylene oxide-based polyether polyols, including highly reactive polyether polyols. Filled with polyether polyol, even amino terminated polyether polyol, low unsaturation polyether polyol, flame retardant polyether polyol, etc.; 3 tetrahydrofuran-based polyether polyol; 4 butadiene-based polyether Polyol 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 water. Kinetic studies of the reaction process for the synthesis of isocyanate-terminated prepolymers have shown that the use of less reactive polymer polyols (e.g., polyoxypropylene containing secondary hydroxyl groups) increases side reactions.

Wang Zongliu, Tar-Hwa Hsieh [24] (1997) studied the thermal stability of a range of polyether polyurethanes using PEG / PPG / PTMG, MDI and ethylene diamine. The effect of the soft chain segment molecular weight and structure on thermal stability. As a result, the thermal stability of PTMG is preferred, which is attributed to the presence of carbamate hydrogen bonds between the molecules.

Vincent (1990) reviewed the hydrolysis, pyrolysis, oxidation and photolysis of polyurethanes. In terms of hydrolytic stability, the mechanism of the carbodiimide structure can improve the hydrolytic stability of the polyester PU; the table is listed and the decomposition mechanism of various groups is given; the figure shows that at 80 ° C, the relative humidity is 95% under certain conditions of the model polymer tested, the order of stability of the polyurethane catalyst from strong to weak is: 1PTMG-HMDI-MDA> 2PTMG-MDI-Bd > 3 polyester-MDI-Bd> 4PTMG-TDI -MBOCA> 5PPG -TDI-MBOCA> 6 polyester-TDI-MBOCA. As can be seen from the above, there are advantages and disadvantages in the soft segment and hard segment components selected above. But still not comprehensive enough.



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