摘要:
Isocyanurate- and/or uretidone-containing polyisocyanates having a reduced color index and improved shelf life are prepared by conventional catalytic oligomerization of aliphatic and/or cycloaliphatic diisocyanates and treatment of the oligomerization products with peroxycarboxylic acids.
摘要:
The invention relates to highly functionalized polyurethanes which are synthesized from molecules containing the functional groups A(B).sub.n, where A is an NCO group or a group reactive with an NCO group, B is an NCO group or a group reactive with an NCO group, A is reactive with B and n is a positive number and is at least equal to 2.
摘要:
A process for the preparation of polyisocyanates which contain one or more biuret groups, by reacting a) an aliphatic or cycloaliphatic isocyanate containing two or more isocyanate groups (isocyanate a) with b) a tertiary alcohol or a mixture of water and a tertiary alcohol (biuretizing agent b) at from 100 to 250° C., which comprises carrying out the reaction in the presence c) of a stabilizer (c) which constitutes a catalytic amount of urea, ammonia, biuret, a urea derivative of the formula I in which R1, R2, R3 and R4 are hydrogen, C1 to C10 alkyl or C5 to C10 aryl, or a carboxamide of the formula II in which R5 is C1 to C12 alkyl which is unsubstituted or in which 1, 2 or 3 hydrogen atoms are replaced by a radical
摘要:
Polyisocyanates containing isocyanurate groups are prepared by a partial trimerization of (cyclo)aliphatic diisocyanates in the presence of at least one trimerization catalyst selected from the group consisting of tetraalkylammonium alkyl carbonates of the formula (I) ##STR1## (quaternary ammonioalkyl) carbonates having a betaine structure of the formula (II) ##STR2## and the preferred use of the polyisocyanates containing isocyanurate groups which are obtainable in this way is aspolyisocyanate component in polyurethane finishes.
摘要:
In a process and an apparatus for preparing (cyclo)aliphatic polyisocyanates containing biuret groups from (cyclo)aliphatic diisocyanates and steam or a substance capable of splitting off water as reactants which are mixed with one another in a stirred reactor, the reactants are passes in countercurrent through a cascade-type stirred reactor comprising at least two stages. The dispersion of the gaseous reactant in the liquid reactant is reinforced by baffles installed in the stirred reactor. As baffles, use is made of discs provided with central openings and arranged at a distance from one another and/or strip baffles running in the longitudinal direction of the stirred reactor.
摘要:
Stable (cyclo)aliphatic polyisocyanate compositions obtainable by phosgene-free methods, preferably by thermal cleavage of (cyclo)aliphatic polycarbamates, are stabilized with carbon dioxide, advantageously in an amount of up to 0.3% by weight.
摘要:
The present invention provides systems, methods and apparatus for depositing titanium films at rates up to 200 .ANG./minute on semiconductor substrates from a titanium tetrachloride source. In accordance with an embodiment of the invention, a ceramic heater assembly with an integrated RF plane for bottom powered RF capability allows PECVD deposition at a temperature of at least 400.degree. C. for more efficient plasma treatment. A thermal choke isolates the heater from its support shaft, reducing the thermal gradient across the heater to reduce the risk of breakage and improving temperature uniformity of the heater. A deposition system incorporates a flow restrictor ring and other features that allow a 15 liters/minute flow rate through the chamber with minimal backside deposition and minimized deposition on the bottom of the chamber, thereby reducing the frequency of chamber cleanings, and reducing clean time and seasoning. Deposition and clean processes are also further embodiments of the present invention.
摘要:
A substrate processing chamber, particularly a chemical vapor deposition (CVD) chamber used both for thermal deposition of a conductive material and a subsequently performed plasma process. The invention reduces thermal deposition of the conductive material in a pumping channel exhausting the chamber. The pumping channel is lined with various elements, some of which are electrically floating and which are designed so that conductive material deposited on these elements do not deleteriously affect a plasma generated for processing the wafer.
摘要:
The invention is to a process for the preparation of biuret-containing polyisocyanates by catalytic reaction of aliphatic and/or cycloaliphatic diisocyanates with a biuretizing agent, where the biuretizing agent employed is water in finely disperse form and the reaction is carried out in the presence of OH-acidic compounds.
摘要:
The process according to the invention for treating water in a treatment plant comprising a reaction chamber in which a biodegradable material present in the water is biodegraded at least partly by microorganisms, in the course of which, at least temporarily, water is transferred out of the reaction chamber into a separating chamber and the biodegradable material and the microorganisms are separated at least partly from the water therein, a return stream comprising biodegradable material and at least some of the microorganisms flowing out of the separating chamber into the reaction chamber via a recycle line, is characterized in that at least some of the following substances: a) the biodegradable material and b) the microorganisms are treated with ozone (O3), an amount of 15 to 150 milligrams of ozone per kilogram of dry substance of the biodegradable material and of the microorganisms being added per hour in the reaction chamber.