The catalyst has a great effect on polyurethane foam, and with it, rapid production at room temperature can be achieved.There are two main categories of catalysts: tertiary amines and metal catalysts, such as triethylene diamine, pentamethyldiethylene triamine, methylimidazole, A-1, etc. Are all tertiary amine catalysts, while stannous caprylate, dibutyltin february cinnamic acid, potassium acetate, potassium caprylate, organic bismuth, etc. are metal catalysts.At present, various delayed, trimer, complex, and low VOC value catalysts have been developed, all of which are based on the above catalysts.
Under multi-catalyst conditions, it is first necessary to understand the characteristics of various catalysts and their principles of action in order to obtain the balance of the polyurethane system, that is, the balance between the foaming speed and the gel speed; the gel speed is balanced with the foaming rate, the foaming speed is balanced with the material fluidity, etc.
Metal catalysts belong to gel catalysts. Conventional tin catalysts have a strong gel effect, but their disadvantages are that they are not resistant to hydrolysis and have poor heat-resistant aging properties.The recent emergence of organic bismuth catalysts should attract attention. It not only has the function of a tin catalyst, but also has good hydrolysis resistance and heat-resistant aging resistance, which is very suitable for combination materials.
Foam stabilizer
Foam stabilizer plays the role of emulsifying foam materials, stabilizing foam and regulating pores, and increasing the miscibility of each component, contributing to the formation of bubbles, controlling the size and uniformity of bubbles, promoting the balance of foam tension, and making the pore wall elastic to retain the pores and prevent bubble collapse.Although the amount of foam stabilizer is not large, it has a significant impact on the pore structure, physical properties, and manufacturing process of PU soft foam.
At present, the domestic use is all hydrolysis-resistant silicone/polyoxygenated olefin ether block oligomers. Due to their application in different foam systems, the proportion of hydrophobic/hydrophilic segments is different, and the tail link changes of the block structure are not the same. Silicon stabilizers for various foam products are produced.Therefore, when choosing foam stabilizers, we must understand their functions and functions, and don't forget to use them indiscriminately, which will cause adverse consequences.For example, soft foam silicone oil cannot be applied to high-rebound foams, otherwise it will cause foam shrinkage, and high-rebound silicone oil cannot be applied to bulk soft foams, otherwise it will cause foam collapse.