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:
Compounds having isocyanate groups with or without blocking, allophanate groups and free-radically polymerizable C—C double bonds, the C—C double bonds being in activated form by virtue of a carbonyl group attached directly to them or by virtue of an oxygen atom in ether function (activated double bonds), derived from polyisocyanates and alcohols A which in addition to the alcohol group also carry an activated double bond (compounds I). The invention additionally relates to radiation-curable formulations and coating compositions comprising the compounds I, to methods for coating using these substances, and to coated articles produced using these methods. Furthermore, the invention relates to the use of the compounds I in radiation-curable compositions such as in casting compositions, dental compounds, composite materials, sealing compounds, adhesives, troweling compounds, printing inks, in photostructurable compositions such as solder resists, photoresists, photopolymeric printing plates, and stereolithography resins.
摘要:
In a compound of the formula I (reactive polymer), L is a, polymer, XY is a reactive radical which is inert toward NCO groups and splits off one or more protective groups Y under acidic, neutral or basic conditions and the radical X bears, after Y has been split off, at least two groups which are reactive toward isocyanates. Also provided are processes for preparing such a polymer and for preparing V a polymer polyol which is obtainable by reacting a polymer of the formula I with an acid or base. A polymer polyol as is obtainable by treatment of a reactive polymer according to the present invention in the neutral, acidic or basic range can be used to produce a polyaddition product or polycondensation product.
摘要:
The present invention relates to new emulsion polymers, to processes for preparing them, and to their use in coating material for the purpose of improving the water resistance.
摘要:
The invention relates to a hydraulic drive, especially for two-cylinder thick matter pumps. Said hydraulic drive comprises at least one main pump (10) embodied as a hydraulic variable displacement pump, and two hydraulically actuatable drive cylinders (20,22) that are each connected to a connection line (16,18) of the main pump (10) by means of pump connections mounted on one end thereof, forming a closed hydraulic circuit, and communicate with each other at the ends thereof opposing the pump connections (24,26) by means of a swinging oil line (28). The hydraulic drive also comprises a feed pump (42), by which means pressurized oil is fed from an oil tank to the current low-pressure side into the hydraulic circuit, and a flushing branch (52), by which means a flushing oil flow is branched off from the current low-pressure side under a limited pressure into the oil tank (44). In order to avoid low-pressure influxes during the reversal process of the main pump (10), the flushing oil flow is blocked and then released in a time-delayed manner during each reversal process of the main pump (10), independently of the differential pressure in the connection lines.
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:
A vinyl polymer is obtainable by polymerizing vinyl monomers in at least two stages by a procedure in which, in a first stage, from 5 to 95% by weight of vinyl monomers are polymerized in an organic solvent or in the absence of a solvent and, in the second stage, from 5 to 95% by weight of the vinyl monomers are polymerized in the presence of the vinyl polymer obtained in the first stage, likewise in an organic solvent or in the absence of a solvent, with the proviso that the polymerization in the second stage is carried out under conditions under which an average molecular weight M.sub.n, which is at least 1,000 higher compared with that of the vinyl polymer, the first stage of results for the vinyl monomers of the second stage in the absence of the vinyl polymer obtained in the first stage.
摘要:
A process for the continuous polymerization of vinyl monomers to form vinyl polymers having a molecular weight M.sub.n of from 1000 to 20,000 comprisesa. carrying out the polymerization within an annular gap from 0.5 to 10 mm in width,b. confining the annular gap on the inner surface with a rotor, andc. carrying out the polymerization at from 110.degree. to 270.degree. C.