How polyurethane foam resists yellowing
Polyurethane soft foam sponge yellowing, has been a long plagued sponge manufacturers, and polyol manufacturers of the problem. Many sponge manufacturers, especially some high-grade sponge manufacturers, are trying to add antioxidants, light stabilizers to improve the anti-yellowing performance of the sponge, but the results are not significant. IRGASTAB?series of antioxidants, especially its revolutionary production IRGASTAB?PUR 68, fundamentally for the sponge yellowing to provide a set of solutions, this paper will be combined with the polyols and sponge production of upstream and downstream characteristics of the sponge, a systematic analysis of sponge yellowing causes, and elaborates on the corresponding solutions.
Usually, from the point of view of additives, sponge yellowing includes the following four kinds: – sponge foaming / processing, due to high temperature caused by thermal oxygen aging yellowing
Air fumigation yellowing caused by exposure to nitrogen oxides (NOx) in the air.
Fabric contamination caused by sponge
Yellowing caused by sponge exposure to ultraviolet light
And these yellowing, often and antioxidant there is a direct relationship. In other words, the presence of antioxidants, both may have a positive inhibition of some of the above yellowing, for example: sponge foaming/processing process of high temperature-induced thermo-oxidative aging yellowing is through the addition of antioxidants to be inhibited; however, it may also play a negative role in the promotion of other types of yellowing, for example: amine antioxidants in the air in the contact with nitrogen oxides (NOx, mainly from automobile exhaust), or ultraviolet light, will promote the yellowing of sponges. or UV rays, will promote sponge yellowing; and antioxidant BHT, is the main causative agent of fabric contamination.
Usually, polyol manufacturers will add a certain amount of antioxidant in polyol, its purpose is to ensure that the downstream foam manufacturers, in the use of polyol foaming process safety production. At present, domestic polyether manufacturers mainly use antioxidant type for BHT and amine antioxidant or phenol thiocyanate compound antioxidant system; while a well-known international polyether manufacturers mainly use some large molecular weight hindered phenolic antioxidant, and amine antioxidant, such as the vapor bar’s IRGANOX 1135 (large molecular weight hindered phenolic antioxidant), and IRGANOX 5057 (amine antioxidant) belongs to the large molecular weight hindered phenolic antioxidant, and amine antioxidant. IRGANOX? 5057 (amine antioxidant) belong to this system.
As a manufacturer in the sponge market, when we get a polyol, we seldom evaluate the effect of the antioxidant system in the polyol on the yellowing of the sponge, except for the considerations of safety, cost and foaming performance. And this often overlooked factors, but hides an important reason for the impact of sponge yellowing.
Usually in the ideal state, the presence of antioxidants in the polyol, in the sponge foaming process, can play a role in inhibiting the high temperature generated by the foaming itself on the polymer aging degradation, not only to ensure the safety of the sponge foaming process, but also effectively prevent the sponge foaming process of the core of the yellowing problem. However, with the completion of the sponge foam, residual antioxidants in the sponge is prone to cause many sponge yellowing problem.
Pervious concrete adhesive stone one-component polyurethane adhesive preparation method
Polyurethane glue is a molecular chain containing urethane and isocyanate-based glue, due to the strong polarity of isocyanate and urethane-based, highly reactive, capable of room temperature curing, and thus has excellent adhesive properties for a variety of materials such as metal, rubber, glass, ceramics, plastics, wood, fabrics, leather, etc., polyurethane’s main chain flexibility is very good, and its most important feature is the resistance to shock vibration and bending fatigue Polyurethane adhesive process is simple, room temperature and heating can be cured, the thermal stress effect is small when different materials are glued, there are a wide range of applications in various fields, polyurethane adhesive water and heat resistance is poor, the selection of the need to pay attention to, due to the wide range of applications of polyurethane adhesive, so the market mountain of polyurethane adhesive There are many varieties, in addition, the application in the field of sponge city permeable concrete adhesive stone has become a hot spot of research in recent years.
Permeable adhesive stone to adapt to the environmental requirements are relatively high, both high strength, but also to have a strong bond, waterproofing, UV resistance, yellowing resistance, aging resistance and other requirements, now on the market with the epoxy resin two-component made of adhesive stone concrete, hardness is very high, there is no toughness, does not tolerate yellowing, UV resistance is poor, the service life is not long, can not achieve the expected results, the current market made of HDI hardener Adhesive stone made of HDI curing agent on the market has not been studied and promoted, although a small number of enterprises also have some research, such as BASF HDI trimer and polyurethane resin made of two-component polyurethane adhesive, due to HDI trimer room temperature reactivity is relatively low, if the construction site operation ratio is a slight error, it will make HDI trimer and polyurethane mixing is not uniform!
