摘要:
(Meth)-acrylic acid derivatives of tricyclodecanes of the formula ##STR1## in which R.sup.1 and R.sup.2 are identical or different and denote hydrogen, lower alkyl, lower alkoxy, halogen or trifluoromethyl and R.sup.3 and R.sup.4 are identical or different and represent the group ##STR2## wherein X denotes a divalent bridge member from the group ##STR3## and Y denotes a divalent bridge member from the group ##STR4## and wherein R.sup.5 represents hydrogen or methyl and R.sup.6 represents lower alkyl or phenyl, have been found. Dental compositions in which the present (meth)-acrylic acid derivatives of tricyclodecanes are used, exhibit considerably less polymerization shrinkage.
摘要:
Compounds of the formula ##STR1## in which R represents hydrogen or a methyl group,Y.sup.1 represents an optionally branched alkylene radical with 1 to 6 C atoms,Y.sup.2 represents an optionally branched alkylene radical with 2 to 8 C atoms,X denotes oxygen or an --NH-- group,R.sup.1 and R.sup.2 are identical or different and denote hydrogen, or an alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, aralkyl or alkylaryl group which has 1 to 11 C atoms and is optionally substituted by one or more,hydroxyl, amino, epoxide, urethane, urea, ester or ether groups, orR.sup.1 and R.sup.2 together form a 3-membered to 6-membered ring, which optionally contains nitrogen, oxygen or sulphur as hetero-atoms,R.sup.3 has the meaning of R.sup.1 or represents a group ##STR2## or R.sup.2 and R.sup.3, together with the ##STR3## group, form a 5-membered or 6-membered ring, which optionally contains oxygen as a further hetero-atom, andR.sup.4 and R.sup.5 are identical or different and represent hydrogen, an alkyl or alkenyl group which has 1 to 10 C atoms and is optionally substituted by halogen, or halogen,function as activators in the free radical polymerization of olefinically unsaturated monomers.
摘要:
The new (meth)acrylic acid derivatives containing urethane groups can be prepared by reaction of a (meth)acrylic acid ester with diisocyanates and subsequent reaction with polyols. The compounds can be used for dental materials.
摘要:
The new (meth)acrylic acid derivatives containing urethane groups can be prepared by reaction of a (meth)acrylic acid ester with diisocyanates and subsequent reaction with polyols. The compounds can be used for dental materials.
摘要:
The present invention is directed to a process for the production of prepolymers containing free tertiary isocyanate groups by reacting(a) an organic diisocyanate containing one isocyanate group attached to a primary aliphatic carbon atom and an isocyanate group attached to a tertiary aliphatic or cycloaliphatic carbon atom with(b) a polyester polyol having a molecular weight of 800 to 12,000 and a hydroxyl functionality of 2 to 6 at an NCO/OH equivalent ratio of 1.6:1 to 2:1 to provide prepolymers having a molecular weight of about 1000 to 3000 and an NCO content of about 4 to 12%.The present invention is also directed to the prepolymers containing free isocyanate groups obtained by this process and to their use for the production of polyurethane lacquers and coatings.
摘要:
The present invention relates to diisocyanates having an isocyanate content of from about 20 to 50% by weight, optionally in the form of isomeric mixtures, characterized in that, in addition to containing a sterically unhindered isocyanate group attached to a primary aliphatic carbon atom, they contain a sterically hindered isocyanate group attached to a tertiary carbon atom which forms part of a cycloaliphatic ring system.The invention also relates to the use of the new diisocyanates, optionally blocked with blocking agents for isocyanate groups, as isocyanate component for the preparation of polyurethanes suitable for use as coatings.
摘要:
New cyclic keto-butyraldehydes of the formula ##STR1## in which R.sub.1 and R.sub.2 are either identical or different and denote hydrogen or lower alkyl and in which the cycloaliphatic ring may contain a double bond, can be prepared from the corresponding cyclic keto-olefins in the presence of a rhodium-containing catalyst by reaction with carbon monoxide and hydrogen. The new cyclic keto-butyraldehydes can be used in the preparation of diisocyanates which are used as crosslinking agents in the preparation of polyurethanes.
摘要:
The present invention relates to diisocyanates having an isocyanate content of from about 20 to 50% by weight, optionally in the form of isomeric mixtures, characterized in that, in addition to containing a sterically unhindered isocyanate group attached to a primary aliphatic carbon atom, they contain a sterically hindered isocyanate group attached to a tertiary carbon atom which forms part of a cycloaliphatic ring system.The invention also relates to the use of the new diisocyanates, optionally blocked with blocking agents for isocyanate groups, as isocyanate component for the preparation of polyurethanes.
摘要:
Aliphatic, araliphatic or aromatic nitriles of the formula R--CN are obtained by reacting N-substituted formamides of the formula R--NHCHO with at least the stoichiometric quantity of an acylating agent (generally a carboxylic acid anhydride, such as acetic anhydride, or ketene) in the gas phase at temperatures above 250.degree. C., without using a catalyst. The process is especially useful in the preparation of nitriles wherein the connecting carbon of R is a tertiary carbon atom. The nitriles are important intermediate products, for example for the preparation of herbicides, surface-active agents and anti-corrosive agents.
摘要:
Compounds of the formula ##STR1## are suitable as curing accelerators which can be incorporated into ethylenically unsaturated, cold-curable resins.