The formula of slow rebound sponge is much the same as that of ordinary sponge.In addition to the large differences in the main polyether, some small materials can be interoperable.However, in order to produce high-quality products, the selection of small materials should still be carefully considered and selected.
Selection of amines
The most classic amine used for slow rebound sponges is Dabco33-LV from American Air Company.Its dosage is generally 0.3-0.8 parts of the total amount of polyether.Judging from the ability to dissolve Sanya ethyl diamine, there are many alcohol compounds that can be used as solvents: for example, propylene glycol, diethylene glycol, ethylene glycol, 1.4-butanediol, etc.
Small molecular weight alcohol can be used as a chain extender or crosslinking agent, which means that these small molecular alcohol can consume TDI. The result is: on the one hand, the TDI index is reduced, and on the other hand, it is easy to cause sponge obturation.
The largest supply in the domestic market is amines formulated with ethylene glycol as the solvent.Some catalyst manufacturers, in order to pursue profits, deliberately reduce the concentration of Sanya ethyl diamine and foam with such amines. In order to ensure catalytic capacity, increase the amount of catalyst. This kind of catalyst containing a large number of small molecule solvents will consume too much TDI. If the amount of TDI is not adjusted, the sponge will become soft and the tendency to close pores will increase.The slow rebound tension and tear strength of this amine are not good.
Some other amines can also rebound slowly, such as 9727, CS90, etc., but they must be rigorously tested before use, and the amplification effect must be considered during production.It is not recommended to use SMP to send slow rebound.When foaming is difficult in winter, 0.1-0.3 parts of A1 catalyst can be added to strengthen the foaming reaction.
Selection of tin
It is recommended to use dibutyltin february cinnamic acid.Stannous caprylate is suitable for medium and low-density sponges.It is characterized by fast adhesion in the early stage, but insufficient stamina.It is used to make high-density sponges, which have poor post-maturation properties.T-9 is easy to hydrolyze, and the slow rebound itself starts slowly (the general control start time is about 160 seconds). If it is in contact with water for a long time, it will be partially hydrolyzed, which will affect maturation.Dibutyltin february cinnamic acid is not hydrolyzed, it starts, gels, matures smoothly, and has good post-maturation properties.
The tension of the sponge is not good, it is recommended to use dibutyl tin february cinnamic acid.If you use T-9, the dosage is 0.1-0.4 servings.Using dibutyltin february cinnamic acid, the dosage is controlled between 0.03-0.05.If the assembly line rebounds slowly, the amount can be reduced to 0.001-0.01 parts.For export orders that restrict the use of tin catalysts, it is recommended to replace tin with bismuth naphthanoate.
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Selection of silicone oil
A typical slow rebound silicone oil is B8002, and its dosage is between 0.5-2 parts.High-density sponges are used less, and low-density sponges are used more.Manual soaking is more versatile, and machine hair is less used.Using L-580 for slow rebound, the amount of silicone oil is reduced. After all, the activity of L-580 is relatively high.