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Jul 8, 2021
They make the pores fine and uniform. When the system is in the low viscosity stage, it stabilizes the pore wall/the pores can grow to a thickness suitable for the opening, creating conditions for the final opening. The type of foam is different, and the type of stabilizer used is also; at the same time, its main function is to nucleate and emulsify each component in the formula. The compatibility of the various components in the foam formulation is not good, so a stabilizer with a strong emulsifying ability is needed to emulsify and mix them uniformly. The soft foam is made of water as a blowing agent, which accounts for 3% to 5% of the weight of the polyether in the formula. The reaction rate of water and isocyanate is higher than that of isocyanate and polyol, so there are a lot of solids in the initial stage of foaming. Polyurea is formed, which is a defoaming agent that can help open and blast holes. Opening and popping are the stages when soft foam foaming must occur, otherwise, closed cells will appear, which will reduce the foam performance. However, the opening and popping must occur when the foaming reaction and the gel reaction are basically completed and reach equilibrium. That is, when the foam rises to the highest point and the strength of the foam can support its own weight, otherwise it will cause the foam to collapse. Therefore, another important function of the soft steam stabilizer is that it can dissolve the polyurea formed by the reaction in the early stage of foaming and can help open and burst holes in the late stage of foaming.
The foam stabilizer can reduce the surface tension of the polyurethane raw material mixture, and prevent the thermodynamically unstable state of the foam from appearing through the surface tension during the foam rise to maturation.Surfactants containing sulfonic acid groups are good stabilizers for polyester foams, such as sulfonated ricinol sodium salt.
Water-soluble polyether siloxane is a stabilizer for polyether foam. It can be modified by molecular weight, functionality, and polyether copolymer to meet different production requirements, such as flat-top foamed block foam, olefin barrier Type polyether soft foam requires different foam stabilizers.
The preparation method of foam stabilizer is to mix polyoxyethylene polyoxypropylene ether, acrylic acid or acryloyl chloride, catalyst, polymerization inhibitor and water-carrying agent, and react to generate intermediate product to obtain alkoxy polyoxyethylene polyoxypropylene ether acrylate; Then alkoxy polyoxyethylene polyoxypropylene ether acrylate is mixed with hydrogen-containing silicone oil and catalyst chloroplatinic acid, and reacted to obtain the above foam stabilizer. The polyurethane foam material prepared by the above foam stabilizer can obtain a uniform size circle Shaped bubbles, the bubble opening rate is higher, and the indentation hardness decreases.
Improve the flame retardant properties of polyurethane foam by replacing conventional silicone surfactants with flame retardant silicone surfactants (oil foam stabilizers). Reduce the amount of flame retardants added under the same flame retardant requirements, or under the same conditions, flame retardant The introduction of silicone oil foam stabilizers has significantly improved the various flame retardant indicators of the foam, and experimental comparisons have been carried out. The results show that the use of flame-retardant silicone surfactants can reduce the amount of conventional formulations (non-flame retardant silicone surfactants) ) The addition amount of flame retardant is 20%～30%, so as to improve the physical properties of the foam.