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Polyurethane divides water agent (1) : The element sifts the agent that remove w

From;  Author:Stand originally

A lot of polyurethane constituent and raw material contain moisture content, the water of dye and layer of only member of filling surface adsorption, additional, dye is met in process of keep in storage adsorbed water. Normally, the dissolve Liu that is used at polyurethane reaction, multivariate alcohol and other constituent need are dry.

If be in,the dissolvent in polyurethane of solvent double constituent did not remove water, because produce carbon dioxide,meet, when causing solidify epispastic. (Article origin is round-the-world polyurethane net) those who contain moisture content is multivariate alcohol and dye are brought about finally carbon dioxide bleb is formed in solidify film, cause size hubble-bubble, pinhole not only, reduce coating burnish possibly still.

The humidity in construction environment can is into the person in the polyurethane of construction, this issue is quite outstanding when spray polyurethane elastomer. Normally base material itself may be damp, this will pose another problems. For example polyurethane safeguards coating to be in commonly damp exterior besmear cloth, environmental moisture and moisture of coating hydroxyl constituent are cleared sordid, can bring about gas of generation carbon dioxide, swimming hole is formed in coating.

So, eliminate moisture needs in polyurethane raw material. Physical method dehydrate is commonly used craft, general oligomer multivariate alcohol is in 120 ℃ of 100 ~ relatively high vacuum spends next decompression dehydrate 1 ~ 2h, can take off except major moisture, achieve use requirement. Solvent can add an element to sift dry, distill, with eliminate moisture. Filling needs stoving before use.

Afore-mentioned methods are used to undertake dehydration without the condition below certain circumstance, can come through adding the agent that remove water eliminate moisture. Physics has an element to sift except water agent (Molecular Sieve) , abroad has an element to sift content product to supply, be screen the member imperceptible powder to get in plasticizer dispersedly.

Molecular sieve is the synthetic zeolite that changes crystallization (person of Synthe small SeoI, sylvite of a kind of special / of siliceous aluminium natrium) the water purify in the structure, namely " activation " , the solid body of obtains small hole powder that has specific aperture. Molecular sieve can choose a mixture of adsorptive young member, include water member, because this certain element sieve is physics,divide water agent (namely desiccative) . The industrial member that company of CECA of sale of French Atofina chemical company produces is sifted, the brand is Si1ipoite, the element sifts pulverous bead diameter to have the norms such as 0.7mm, 1.0mm, 1.3mm, 1.6mm, 2.0mm. Can be used at odd constituent and system of double constituent polyurethane remove water (bibulous, dry) the agent basically is Siliporite NK30 and Siliporite SAl720, have powder and mushy product form, if express 13, 1 is shown.