Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1999-08-10
2000-10-03
Hampton-Hightower, P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
528 28, 528 30, 556403, 501 88, 501 90, 501 961, 501 965, 423290, 264667, 264669, C08G 7908, C08G 7912, C01B 2106, C01B 2164, C04B 3558
Patent
active
061275107
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to novel C/N-- and B/C/N polymers which can be obtained by reaction of carbodiimides R.sub.3 E--NCN--ER.sub.3 (R=alkyl, aryl; E=Si, Ge, Sn) with halogenotriazines and their use for producing C/N and B/C/N materials.
DE-OS (German Published Specification) 44 30 817 discloses polymeric ceramic precursors which are obtainable by reaction of bis(trialkylsilyl)carbodiimide with halides of groups IIIA, IVA and VA of the Periodic Table. In particular, the reaction of bis(trimethylsilyl)carbodiimide with silicon tetrachloride is described there.
It has now been found that novel polymers can be prepared by reaction of carbodiimides of the type R.sub.3 E--NCN--ER.sub.3 (R=alkyl, aryl; E=Si, Ge, Sn) with halogenotriazines.
DESCRIPTION OF THE INVENTION
The reaction of cyanuric halides (2,4,6-trihalogeno-s-triazines) with silyl, germyl and stannyl carbodiimides leads to new, infusible pulverulent polymers which are suitable for conversion into carbon nitrides, in particular C.sub.3 N.sub.4. Borazine halides react analogously to form polymers from which boron carbonitrides can be obtained by thermolysis.
To prepare the C/N and B/C/N polymers of the invention, use is made of silyl, germyl or stannyl carbodiimides of the type R.sub.3 E--NCN--ER.sub.3, where R symbolizes an alkyl or aryl group, in particular a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, octyl, phenyl or benzyl group, and E represents silicon, germanium or tin.
The carbodiimides are reacted with halogenotriazines. These can be cyanuric halides ##STR1## or borazine halides ##STR2## where X can be fluorine, chlorine, bromine or iodine and R represents hydrogen atoms or alkyl or aryl radicals, in particular H or methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, octyl, cyclohexyl, phenyl or benzyl groups.
The formation of the polymers of the invention is catalysed by addition of a base. As catalyst, preference is given to pyridine in amounts of from 0 to 2 equivalents, preferably from 0.1 to 2 equivalents, based on the molar amount of cyanuric halide or borazine halide.
The C/N polymers of the invention are formed according to the following overall reaction: N.sub.3)(NCN).sub.1.5 ].sub.n +3nR.sub.3 EX
The formation of the B/C/N polymers of the invention occurs analogously: .fwdarw.[(B.sub.3 N.sub.3 R.sub.3)(NCN).sub.1.5 ].sub.n +3nR'.sub.3 EX
The preparation of the C/N and B/C/N polymers of the invention can be carried out either in the absence of solvents or in water-free, inert solvents, e.g. THF, diethyl ether or toluene. For a given solvent and a given starting material combination, the reaction time depends on the amount of base added and the reaction temperature, in general, the reaction times are from 1 to 240 hours, preferably from 1 to 96 hours, and the reaction temperatures are from 20 to 180.degree. C., preferably from 20 to 110.degree. C.
The C/N and B/C/N polymers of the invention are usually obtained as powders and can, after their preparation, be subjected to a drying step in which volatile reaction products, catalyst and any solvent are removed. This is preferably carried out under reduced pressure, at temperatures of from 0.degree. C. to 150.degree. C.
Products free of end groups can be obtained by calcination in vacuo or in an N.sub.2 or noble gas atmosphere (e.g. argon, helium) at temperatures of up to 450.degree. C. Hard materials or (functional) ceramics can be produced from the polymers of the invention by pyrolysis or high-pressure pressing at pressures of up to 20 GPa in an N.sub.2, Ar or He atmosphere. For this purpose, the polymers are, in a procedure similar to diamond production, converted into three-dimensional crosslinked hard material phases in high-pressure presses or by shock-wave compression at pressures of <10 kbar and temperatures of <200.degree. C. The novel materials can be used wherever cemented carbides, ceramics such as c-BN or SiC and diamond are utilized as abrasives or for cutting, drilling and milling app
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Greiner Axel
Kroke Edwin
Riedel Ralf
Bayer Aktiengesellschaft
Gil Joseph C.
Hampton-Hightower P.
Henderson Richard E. L.
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