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:
A process for the preparation of polyricinoleic acid esters comprising the step of reaction of ricinoleic acid with an alcohol component which comprises mono- and/or polyfunctional alcohols having a molecular weight of ≧32 g/mol to ≦40 g/mol, wherein the reaction is carried out at least partly in the presence of a catalyst. The amount of catalyst, based on the total weight of the ricinoleic acid and the alcohol component, is in a range of from ≧10 ppm to ≦100 ppm. The reaction is ended when the acid number of the reaction product obtained is ≧5 mg of KOH/g to ≦100 mg of KOH/g. The invention furthermore relates to a polyurethane polymer, in particular a flexible polyurethane foam, which is obtainable using these polyricinoleic acid esters.
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.
摘要:
The present invention provides improved variants of T7 RNA polymerase by introducing novel mutations which lead to improved thermostability of the enzyme. According to the invention, amino acid substitutions at the positions Val426, Ser633, Val650, Thr654, Ala702, Val795, and combinations thereof are advantageous.
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:
The invention relates to a process for the preparation of liquid, storage-stable isocyanate mixtures of low color number and which contain carbodiimide (CD) and/or uretonimine (UI) groups, the isocyanate mixtures obtainable by this process, and to a process for the preparation of blends of these isocyanates with additional isocyanate components and to a process for the preparation of prepolymers containing isocyanate groups and of polyurethane plastics, preferably polyurethane foams.
摘要:
Polyurethane (PUR) cast elastomers are produced from NCO-functional prepolymers based on 2,4′-MDI satisfying specific compositional requirements and amine-based chain extenders and/or crosslinking agents.