摘要:
Disclosed are rigid polyurethane-polyisocyanurate foams prepared from polyisocyanates, polyols, trimer catalysts and a blowing agent mixture comprising (i) a halocarbon, and (ii) an organic carboxylic acid, and, optionally water. The foams have excellent aged K-factor values at fluorocarbon levels reduced by up to 75 percent over prior art materials.
摘要:
A thermosetting resin composition which comprises a cyanate compound or an isocyanate compound represented by the following general formula (I): A - R₁ - A (I) wherein R₁ is an aromatic group, an alicyclic group or a mixed group thereof and A is a cyanate group or an isocyanate group, and a poly-(p-hydroxystyrene) derivative represented by the following general formula (II): wherein X is a fluorine atom, a bromine atom and a chlorine atom, R₂ is an alkenyl group and an unsaturated carboxyl group, each having 2 to 4 carbon atoms, B is any one of a polymerization initiator residue, a polymerization-terminating agent residue, H and m is an integer of 1 to 4 and n is an integer of 5 to 100, and further containing a compound having at least one N-substituted unsaturated imido group, if required, can produce a printed circuit board of high flame retardness, low dielectric constant, low moisture absorption and a high mechanical strength at an elevated temperature.
摘要:
Rigid polyisocyanurate foams are prepared by (a) bringing together on a continuously advancing conveyor an organic polyisocyanate, a minor amount of a polyester polyol, a blowing agent and, in an organic solvent, a catalyst mixture comprising: (i) a salt of a low molecular weight carboxylic acid selected from the group consisting of an alkali metal salt and an alkaline earth metal salt and mixtures thereof, and (ii) a tertiary amine, the amount of the salt of the low molecular weight carboxylic acid being sufficient and the molecular weight of the carboxylic acid of the salt being sufficiently low to provide a firm foam having a nonfriable surface, and (b) foaming the foam-forming mixture.
摘要:
Highly flame resistant rigid urethane-isocyanurate foams, are prepared from compositions containing blowing agent, a polyester polyol derived from the residue of dimethyl terephthalate or terephthalic acid production, a phosphorus containing polyol and an isocyanurate catalyst, In which the NCO : OH ratio is 3 to 6.
摘要:
Zur Herstellung von kompakten, wärmebeständigen Urethan- und Isocyanuratgruppen enthaltenden Kunststoffen, die beim Aushärten in Formen im wesentlichen keinen Schrumpf zeigen, werden Mischungen aus isomeren Diphenylmethan-diisocyanaten und vorzugsweise Mischungen aus isomeren Diphenylmethan-diisocyanaten und Polyphenyl-polymethylen-polyisocyanaten mit einem Gehalt an 2,4'-Diphenylmethan-diisocyanaten kleiner als 20 Gew.%, mit Polyether-polyolen, die 3 bis 50 Gew.%, bezogen auf das Gesamtgewicht, dispergierte Polymerpartikel, Polyharnstoffe und/oder Pfropfpolymere enthalten, in Gegenwart von Cyclisierungs- oder Polymerisationskatalysatoren für Polyisocyanate und gegebenenfalls Hilfsmitteln und Zusatzstoffen zur Reaktion gebracht. Die nach dem erfindungsgemäßen Verfahren hergestellten Kunststoffe eignen sich insbesondere zur Herstellung von Trennstegen zur thermischen Trennung von Aluminiumprofilen.
摘要:
The invention regards a composition for preparing a polyisocyanurate consisting of: a) aromatic polyisocyanates; b) compounds having groups reactive towards isocyanates; c) possible additives.