摘要:
A process for stabilizing homo- or copolymeric polyolefins, especially polypropylene, with certain symmetrical or asymmetrical diacyl dihydrazides is disclosed, said diacyl dihydrazides possessing good color properties, and said process being particularly advantageous with respect to thermooxidative decomposition in the presence of transition metals.
摘要:
Sterically hindered piperidines having at least 5 alkyl groups in ring positions 2,3,5 and 6 are usable as light-stabilizers for organic polymers. The nitrogen may be unsubstituted or may bear a mono- to tetravalent substituent. The compounds can be synthesized by a Wolf-Kishner reduction of polyalkyl 4-oxopiperidines optionally followed by a N-substitution reaction in a second step.The stabilizers are added to the polymers in an amount of from 0.01 to 5% by weight. Preferred is the stabilization of polyolefins, styrene polymers, polyamides and polyurethanes.
摘要:
2,2,6,6-Tetramethyl-4-oxopiperidine is prepared from 2,2,4,4,6-pentamethyl-2,3,4,5-tetramethylpyrimidine (acetonine) by heating in the presence of acetone, diacetone alcohol or water. These regents may be used in excess or an organic solvent is added. The preferred modification is the heating of acetonine hydrate in an excess of acetone or in an acetone-methanol mixture to about 40.degree. to 65.degree.C for several hours. The use of diacetone alcohol permits higher reaction temperatures leading to shorter reaction times.
摘要:
Cyclic ketals of sterically hindered 4-oxopiperidines are effective light-stabilizers for organic polymers. These compounds have at least five alkyl groups in ring positions 2,3,5 and 6 and four alkyl groups in ring positions 2 and 6, preferably methyl and ethyl groups. The ring nitrogen may be unsubstituted or substituted with a monvalent substitutent. The new compounds can be synthesized by ketalization of the corresponding 4-oxopiperidines with diols, triols or tetrols. Using triols the obtained ketals possess hydroxyl groups which may be esterified or etherified in a subsequent reaction step. Ketalization with tetrols yields cyclic bis-ketals.
摘要:
New 3,5-dialkyl-4-hydroxybenzyl-oxiranes and the corresponding thiiranes are used as stabilizers for polymers. The oxiranes are prepared from the corresponding olefins by reaction with percarboxylic acids or from alkali phenoxides and epichlorohydrines. The thiiranes are prepared from the oxiranes by the usual sulfidation methods.
摘要:
2,2,6,6-Tetramethyl-4-oxopiperidine is prepared from 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine by treatment with an acidic catalyst. Suitable catalysts are Lewis acids, protonic acids and their salts with ammonia or organic bases. The reaction may be carried out in organic solvents, preferably in acetone, by gentle heating, for example at 40.degree. to 65.degree.C. Yields of 95% are obtainable after a reaction of several hours.
摘要:
Polymers, both natural and synthetic, are stabilized against the deterioration resulting from heat and/or light by the incorporation of certain 2,2,6,6-tetra-substituted-4-piperidinol derivatives which additionally have an alkyl, alkenyl, alkynyl or aralkyl substituent at one or both of the 3- and 5- positions.
摘要:
Novel 7,7,9,9-tetra-substituted-1,3,8-triazaspiro�4.5!decane-2,4-diones having an alkyl or allyl group at either the 6- or the 10- position are useful for the stabilization of polymers against photo- and thermal- deterioration.