Slow rebound sponge formulas for the use of small materials
Slow rebound sponge and ordinary cotton formula is similar. In addition to the main material polyether has a big difference, some small materials can be used interchangeably. But in order to produce high-quality products, the selection of small materials should be carefully considered selection.
First, the choice of amine
The most classic amine used in slow rebound sponge, the first American air company’s Dabco33-LV, its dosage is generally 0.3-0.8 of the total amount of polyether. It is made from 33% triethylenediamine and 67% dipropylene glycol (DPG). The reason why this product is recommended is because the solvent it uses is Dipropylene Glycol Mono-Contracted. One might ask, is a solvent that important? The answer is yes. There are many other alcohols that can be used as solvents in terms of their ability to dissolve triethylenediamine: propylene glycol, diethylene glycol, ethylene glycol, 1.4-butanediol, etc. However, only dipropylene glycol monohydrate has the highest molecular weight and the lowest hydroxyl value of these small molecular alcohols. As we all know, small molecular weight alcohols can be used as chain extender or cross-linking agent, which means that these small molecular weight alcohols can consume TDI, which results in lowering the TDI index on the one hand, and easy to cause sponge closure on the other hand.
Before 2012, only a few countries in the world can produce DPG with purity above 99%, and only one factory in Anhui Province can produce DPG with purity close to 95%, which is a few percentage points difference in purity, and the domestic DPG condenses at room temperature, which can not be used as a solvent, and thus restricts the localization of amine catalysts using DPG as a solvent. Therefore, the most supplied amines in the domestic market are those formulated with ethylene glycol as solvent. Some catalyst manufacturers, in order to pursue profits, deliberately reduce the concentration of triethylenediamine, with such an amine foam, in order to ensure the catalytic capacity, it is inevitable to increase the amount of catalyst, this catalyst containing a large number of small molecules of solvents, will consume too much TDI, if you do not adjust the amount of TDI, the sponge will become soft, the tendency to increase the closed cell. In addition, the slow rebound tensile strength and tear strength of this amine are not good.
It is believed that with the progress of domestic chemical separation engineering technology, there will be more and more high purity DPG will come out, and the domestic Dabco33-LV will be more and more. Of course, some other amines can also send slow rebound, such as 9727, CS90, etc., just before using must do rigorous small test, production should consider the amplification effect. It is not recommended to use SMP to send slow rebound. In the winter foaming difficulties, you can add 0.1-0.3 parts of the A1 catalyst to strengthen the foaming reaction.
Second, the choice of tin
The master of the ordinary sheep hair like to use stannous octanoate (T-9) hair slow rebound, but I recommend using dibutyl tin dilaurate (D22, T-12, also known as the domestic K-19). Stannous octoate is suitable for medium and low density sponges. It is characterized by fast viscosity in the early stage, but not strong enough. Used to hair high-density sponge, after cooking bad.T-9 easy to hydrolyze, slow rebound itself starting slow (general control of starting time in 160 seconds or so), its contact with water for a long time, there will be part of the hydrolysis off, affecting the cooking. Dibutyltin dilaurate is not hydrolyzed, hair, gel, smooth maturation, good after maturation.
Once some colleagues said that the sponge tension is not good, I suggested using dibutyltin dilaurate, the feedback is that the tension has improved. If you use T-9, the dosage is 0.1-0.4 parts. If you use dibutyltin dilaurate, the dosage can be controlled between 0.03-0.05. In the case of assembly line slow rebound, the dosage can be reduced to 0.001-0.01 parts. For export orders that restrict the use of tin catalyst, the author suggests that bismuth naphthenate can be used to replace tin.
Third, the choice of silicone oil
Typical slow rebound silicone oil is B8002, the amount of 0.5-2 copies. High-density sponge less, low-density sponge more. Handmade foam is used more, and machine hair is used less. In recent years, domestic silicone oil suppliers have developed a lot of silicone oil for slow rebound, performance is also good. Also useful L-580 hair slow rebound, the amount of silicone oil at this time to reduce, after all, L-580 activity is relatively high.
Fourth, the choice of porous agent
About the history, status quo, performance, application of pore-opening agents, has been briefly described in the previous articles, here will not repeat.
Fifth, slow rebound sponge is also used in the flame retardant, because such a list is not much, will not be discussed here.
Sixth, the use of pigments and ordinary sheep are basically the same, but also skipped. Just meet the black sheep should pay attention to, because the preparation of black color paste of carbon black with hydrophobicity, will affect the compatibility of the components in the formula and the efficiency of the catalyst!
Translated with www.DeepL.com/Translator (free version)
