| 摘要 |
<p>1487026 Polyurethane foams BAYER AG 15 Sept 1975 [17 Sept 1974] 37744/75 Heading C3R Cold-curing, high resilient polyurethane foams are prepared by reacting a modified polyisocyanate, defined below, with a compound having at least 2 isocyanate reactive hydrogen atoms and a molecular weight of from 400 to 10,000 in the presence of water and/or an organic blowing agent, the modified polyisocyanate being prepared in a preliminary stage immediately before foaming. The time between the preparation of the modified polyisocyanate and the polyurethane forming reaction is generally from 0À1 seconds to 20 minutes. The modified polyisocyanate is either continuously delivered to the mixing head used for foaming immediately after its production or where the foaming is carried out intermittently, provision is made for brief intermediate storage within the above defined time limits. The modified polyisocyanates are polyisocyanates containing carbodiimide, biuret, allophanate, urethane or isocyanurate groups. Suitable compounds having at least 2 reactive hydrogen atoms and a M.Wt. of 400- 10,000 include compounds containing amino, thiol or carboxyl groups, but are preferably polyhydroxyl compounds containing 2-8 OH groups, e.g. OH-containing polyesters, polyethers, polythioethers, polyacetals, polycarbonates, polyamides and polyesteramides numerous examples of which are given, polyethers modified by vinyl polymers, OH-containing polybutadienes, polyols containing urethane or urea groups, castor oil, starch, other carbohydrates and addition products of alkylene oxides with phenol-HCHO or urea-HCHO resins. Optional additives include cross-linkers having a M.Wt. of 32 to 400, e.g. alkylene glycols, ethylene diamine, aniline, trimethylolpropane, hydrazine and alkanolamines; catalysts, e.g. tertiary amines, Mannich bases, silaamines, tetraalkyl ammonium hydroxides, alkali metal hydroxides, alkali metal phenolates or alcoholates, and hexahydrotriazines; foam stabilizers; flame retardants; reaction retarders; cell regulators; fillers and other conventional additives, for all of which additives examples are listed. The foam may be prepared by the one-stage process, or by the prepolymer or semi-prepolymer process. In the examples high resilient polyurethane foams having sag factors ranging from 2À8 to 3À1 and whose compressiondeformation curves show hardly any plateau are prepared by first preparing a modified polyisocyanate by reacting an 80/20 mixture of 2,4-/ 2,6-tolylene diisocyanate with either (1) a propylene oxide/ethylene diamine polyether in the presence of bismuth octoate as catalyst, or with (2) a propylene oxide trimethylolpropane polyether and ethylene glycol in the presence of bismuth octoate as catalyst, or with (3) a propylene oxide/trimethyol propane polyether in the presence of (a) either triethylene diamine alone or together with tin dioctoate as catalyst or (b) ethylene glycol and tin dioctoate; or (4) in the presence of bismuth octoate and a Mannich base of dimethylamine, phenol and formaldehyde; and immediately afterwards reacting the modified polyisocyanate with the following formulation: an ethylene oxide capped trimethylolpropane/propylene oxide polyether, water, triethylene diamine, trichloroethyl phosphate and either (A) diethanolamine and a foam stabilizer, or (B) diisopropanolamine and triethanolamine.</p> |
