Patent GB-1033772-A (GB)
Title: Improvements relating to polycaprolactam foams
IPC: C08J9/10
Filed: 1963-01-28
Abstract: The invention comprises aliphatic allylic azides having 8-24 carbon atoms in the molecule and certain benzyl azides, particularly those having an alkyl substituent in each position ortho to an azidomethyl group. Azides specified are: 1-azido-5,5,7,7-tetramethyl octene - 2, o - methylbenzyl azide, m-methyl benzyl azide, 3,4-dimethyl benzyl azide, 2,4,5-trimethylbenzyl azide, dodecylbenzyl azide, p-phenoxybenzyl azide, a 1,a 4-diazidohexamethylbenzene, and a 1-azidomethyl-2,3,5,6-tetramethyl benzene.  The compounds may be prepared by reacting the corresponding allylic halide with an alkali metal azide, e.g. sodium azide, in a polar solvent, e.g. 95-98% aq. ethanol at reflux temperature and atmospheric pressure.ALSO:A foamed polycaprolactam is prepared by heating a molten composition of e -caprolactam, an anionic polymerization catalyst, a cocatalyst and an alkylic azide foaming agent containing at least one azidomethyl group directly attached to a carbon atom which is in turn bonded to another carbon atom by a double bond, said carbon atoms forming part of an aliphatic chain or an aromatic ring, and having a decomposition temperature of 100-215 DEG  C., at a temperature within this range until it solidifies. Azides specified are 1-azido-5,5,7,7-tetramethyloctene - 2, 0 - methylbenzyl azide, m-methylbenzyl azide, 3,4-dimethylbenzyl azide, 2,4,5-trimethylbenzyl azide, dodecyl benzyl azide, p-phenoxybenzyl azide, a 1,a 4-diazidohexamethyl benzene, a 1-azidomethyl-2,3,5,6 -tetramethylbenzene, dodecenyl azide, 2,4,6-tris - (azidomethyl) mesitylene, and 1 - tertbutyl - 3,5 - dimethyl - 2,4,6 - tris - (azidomethyl) benzene.  The azide may be added to a melt containing the catalyst, cocatalyst and caprolactam at 100-215 DEG  C. or the azide and cocatalyst may be dissolved in one portion of the lactam at 140-160 DEG  C. and this added to a second portion containing the catalyst, within the same temperature range 0.4-14.0 moles of catalyst and 0.2 to 2.0 moles of cocatalyst may be used per 100 moles of caprolactam. Catalysts specified: alkali and alkaline earth metals, Zn and Al as free metals, hydrides, alkoxides, hydroxides or carbonates, Grignard reagents, NaNH2, MgNH, Mg(NH2)2, Mg[N(CH3)2]2, Mg(NHPh)2, ZnEt2, MgPh2, AlPri3, NaEt, LiAlH4, ketenes, acid chlorides, anhydrides, halogenated ketones, dilactim ethers and benzimido compounds.  Specified cocatalysts are isocyanates, diisocyanates, N,N-dihydrocarbyl carbamyl chlorides, symmetrical triazines with aryloxy, alkaryloxy, halogen, hydrogen, dialkylamino, alkyl, alkenyl or aryl as substituents, polyfluoromethylene sulphides and the combination of a symmetrical triazine with the urea or thiourea, R1NHC=XNR2R3. Other lactams e.g. enantholactam, pyrrolidone, or piperidone may be present during polymerization step. The product may be moulded, e.g. into a bowling pin.  In Example (2) a mixture of e -caprolactam, NaOMe, potassium stearate, methylene bis-(4-methyl isocyanate) and optionally a polyamide was foamed.  In Example (3) a mixture of sodium dicaprolactam, caprolactam, potassium stearate, TiO2, 1,4 - diazidomethyl - 2,3,5,6 - tetramethylbenzene and either diphenoxytriazine or diphenyl carbamyl chloride was foamed. In Example (4) the foamed mixture was sodium caprolactam, potassium stearate, dimethylaminodichlorotriazine and 1,4 - diazidomethyl - 2,3,5,6 - tetramethyl - benzene.  The last 2 compounds are replaced in Example (5) by 1,3-dimethylurea, in (6) the 1,4-diazidomethyl - 2,3,5,6 - tetramethyl - benzene was replaced by dodecenylazide, in (7) 1,3-dimethylurea was also added, and in (9) 2,3,5,6tetramethyl -benzyl azide was used in place of 1,4 - diazidomethyl - 2,3,5,6 - tetramethylbenzene.