摘要:
The present invention relates to a process for the preparation of clear, storage-stable isocyanate-terminated prepolymers. These isocyanate-terminated prepolymers are based on hexanediolether carbonate. This invention also relates to the preparation of polyurethanes from these isocyanate-terminated prepolymers.
摘要:
The present invention relates to a process for the preparation of carbodiimide- and/or uretonimine-modified polyisocyanates by means of microwave radiation and to the use of such polyisocyanates for the synthesis of foamed and non-foamed polyurethane materials.
摘要:
The present invention provides an electromechanical transducer comprising a dielectric elastomer with contact by a first electrode and a second electrode, said dielectric elastomer comprising a polyurethane polymer comprising the reaction product of A) a polyisocyanate and/or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups wherein the polyisocyanate prepolymer B) and/or the compound C) having at least two isocyanate-reactive groups comprise polytetramethylene glycol ether units of the formula (I): —[O—CH2-CH2-CH2-CH2-]n (I) where n≧25; and with a minimum value nmin for the value n and a maximum value nmax for the value n in the formula (I) selected such that the difference between nmax and nmin is ≧0 to ≦4. The present invention further provides a process for producing such an electromechanical transducer, and to an electric and/or electronic device including the inventive electromechanical transducer.
摘要:
The present invention relates to polyurethane/polyurea elastomers (PU elastomers) having improved processing characteristics, such as for example extended casting time and reduced brittleness, and occupational health and safety advantages, such elastomers being suitable for replacing elastomers based on TDI prepolymers in comparable applications, and to a process for their production and their use.
摘要:
Polyurethane prepolymers are described which are prepared from 2,4′-diiso-cyanate diphenylmethane (2,4′-MDI), a polyol component and an aliphatic diisocyanate. These prepolymers can be cured with aliphatic, cycloaliphatic and/or aromatic amines to form a cured urethane elastomer. In comparison to cured urethane elastomers based on monomeric 2,4′-MDI, these prepolymers provide elastomers with extended pour life, i.e. they exhibit a slower rate of viscosity buildup after curative and prepolymer are mixed which results in a reduced propensity to crack during the curing process and gives the opportunity to cast larger parts. In comparison to polyurea/urethanes prepared from cured TDI-prepolymers and which optionally include H12-MDI, the prepolymers of the invention have better health and safety aspects.
摘要:
This invention relates to a process for producing prepolymers, which contain isocyanate terminal groups and which have a very low content of free isocyanate starting materials, from polyester polyols and polyisocyanates.
摘要:
Polyurethane prepolymers are described which are prepared from 2,4′-diiso-cyanate diphenylmethane (2,4′-MDI), a polyol component and an aliphatic diisocyanate. These prepolymers can be cured with aliphatic, cycloaliphatic and/or aromatic amines to form a cured urethane elastomer. In comparison to cured urethane elastomers based on monomeric 2,4′-MDI, these prepolymers provide elastomers with extended pour life, i.e. they exhibit a slower rate of viscosity buildup after curative and prepolymer are mixed which results in a reduced propensity to crack during the curing process and gives the opportunity to cast larger parts. In comparison to polyurea/urethanes prepared from cured TDI-prepolymers and which optionally include H12-MDI, the prepolymers of the invention have better health and safety aspects.
摘要:
An isocyanate-terminated prepolymer C having an NCO content of from ≧26% by mass to ≦31.0% by mass is obtainable from the reaction of an isocyanate composition A having a viscosity at 25° C. of from ≧60 mPas to ≦800 mPas, comprising from ≧25% by mass to ≦60% by mass MDI and from ≧40% by mass to ≦75% by mass pMDI, wherein the sum of the amounts of those components is ≦100% by mass, with a bifunctional polyester ether polyol B having an OH number of ≧200 mg(KOH)/g and ≦500 mg(KOH)/g, obtained from the reaction of a dicarboxylic acid/dicarboxylic acid derivative with at least one polyol and with an epoxide, wherein the polyester ether polyol B is used in amounts of from ≧1.5% by mass to ≦6.0% by mass, based on the sum of the masses of A and B. The invention further provides a PUR/PIR polymer produced from the prepolymer C, its use and composite elements based thereon.
摘要:
A measuring device and method according to the invention for registering an ambient temperature Ta of a medical machine including a measuring housing, which is arranged on an outer wall of the machine and in which at least one temperature sensor remote from the machine and at least one temperature sensor (16, 16′) near to the machine are held, wherein the at least one temperature sensor remote from the machine registers a first temperature T1 and the at least one temperature sensor near to the machine registers a second temperature T2, and an evaluation apparatus configured to establish the ambient temperature Ta using a difference between the first temperature T1 registered by the at least one temperature sensor remote from the machine and the second temperature T2 registered by the at least one temperature sensor near to the machine.
摘要:
Isocyanate mixtures comprising: (a) NCO prepolymers having an NCO content of 1.5 to 18 wt. %; and (b) 1 to 40 wt. % of monomeric 2,2′-diisocyanatodiphenylmethane, based on the isocyanate mixture; wherein the isocyanate mixture has a total NCO content of from 2 to 22 wt. %; polyisocyanate polyaddition products prepared therefrom; and methods of making the same.