摘要:
This invention relates to a process for the production of polyurethanes, particularly polyurethane foam moldings having a compact skin and a cellular core, using special tin activators.
摘要:
A process for the production of an optionally cellular polyurethane by reacting at least one compound having at least two hydrogen atoms which are reactive with isocyanate groups and have a molecular weight of from about 400 to 10,000 with polyisocyanates in the presence of a poly(dialkylaminoalkyl)ether catalyst corresponding to the formula ##STR1## wherein A represents a straight-chain or branched-chain (x+1)-valent, optionally substituted C.sub.2 -C.sub.6 alkyl radical,x represents an integer of 1 to 4 andR.sup.1 -R.sup.4 represent the same or different C.sub.1 -C.sub.4 alkyl radicals, which optionally form a heterocyclic radical with N.
摘要:
The present invention provides a mixture containing a) at least 26 wt. % of gadolinium and b) one or more elements, alloys and/or compounds from the group consisting of barium, indium, tin, lanthanum, molybdenum, niobium, tantalum, zirconium and tungsten, a process for the preparation of this mixture, use of the mixture as radiation protection, use of the mixture to prepare polymeric radiation protection substances, a process for preparing radiation screening rubbers, thermoplastic materials and polyurethanes, a process for preparing products from the polymeric radiation protection substances and products made from these polymeric radiation protection substances.
摘要:
A distinct female cultivar of Salix viminalis×S. miyabeana named ‘Otisco’, characterized by rapid stem growth producing greater than 42% more woody biomass than one of its parents (‘SX64’) and 33% more biomass than a current production cultivar (‘SV1’). ‘Otisco’ produced greater than 2.5-fold more stem biomass than two other current production cultivars, ‘SX67’ and ‘SX61’. ‘Otisco’ can be planted from dormant stem cuttings, produces multiple stems after coppice, and the stem biomass can be harvested when the plant is dormant. In the spring following harvest, the plant will re-sprout very vigorously, producing new stems that can be harvested after two to four years of growth. This harvest cycle can be repeated several times. The stem biomass can be chipped and burned as a source of renewable energy, generating heat and/or electricity. ‘Otisco’ displays a low incidence of rust disease and is not damaged by potato leafhoppers.
摘要:
The present invention is directed to a reactive polyurethane mixture comprising:A) at least one polyisocyanate,B) a polyol mixture comprising:B1) at least one polyol containing three or more hydroxyl groups and having a molecular weight in the range from 800 to 6,000,B2) at least one polyol containing three or more hydroxyl groups and having a molecular weight in the range from 400 to 799 andB3) at least one polyol containing three or more hydroxyl groups and having a molecular weight in the range from 92 to 399, andC) at least one polyamine.
摘要:
The invention relates to a process for improving the flowability and preventing the agglomeration of finely divided dimerized 2,4-toluene diisocyanate in which a precipitated silicas and/or pyrogenic silica having a hydrophobic surface is added to the finely divided dimerized 2,4-toluene diisocyanate. The invention also relates to the finely divided dimerized 2,4-toluene diisocyanate prepared by this process.
摘要:
The present invention relates to N,N'-bis-(4-isocyanatocyclohexyl)urea obtained from the reaction with water of cyclohexane-1,4-diisocyanate having a high trans isomer content. This invention further relates to the process for preparing the N,N'-bis(4-isocyanatocyclohexyl)urea and to its use in the synthesis of polyurethanes.
摘要:
Low molecular weight 4,4'-diphenylmethane-uretdione-diisocyanates corresponding to the formula: ##STR1## wherein n is a number from 0 to 1,are made by dimerizing diphenylmethane-4,4'-diisocyanate at a temperature of 50.degree. C. or less in a mixture of non-polar and moderately polar solvents in the presence of a dimerization catalyst. The dimerization product may then be worked up at low temperatures (i.e., .ltoreq.50.degree. C.). The dimerization products of diphenylmethane-diisocyanate thus obtained generally have only a small amount of oligomeric uretdione-diisocyanates present. These dimerization products may be used advantageously in the synthesis of polyurethanes.
摘要:
Diisocyanates corresponding to the formula ##STR1## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 (an isocyanate-containing radical) are as defined herein are made by several processes. These diisocyanates may be made by phosgenating the diamine in which the diisocyanate is based. They may also be produced by treating the bis-urethane of the tertiary alcohol corresponding to the diisocyanate with phosgene. Such diisocyanates may also be made by treating a specific type of bis-urea with hydrogen chloride. The diisocyanates corresponding to the above-given formula are particularly useful in the production of polyurethanes having good flame-proof and mechanical properties.