Patent GB-1057782-A (GB)
Title: Polymerisation of lactams
IPC: C08G69/20
Filed: 1965-02-24
Abstract: In Example B caprolactim ethyl carbonate <FORM:1057782/C2/1> is prepared by adding ethyl chloroformate to methoxy-caprolactim. Reference has been directed by the Comptroller to Specification 945,218.ALSO:A polyamide may be prepared by polymerizing a lactam under anhydrous conditions in the presence of an anionic catalyst and, as promoter a compound of formula R1OCOOR2 wherein R1 is either a heterocyclic radical containing the grouping >C=N- attached to the carbonate group through one of the valencies of the carbon atom or a radical derived by removal of a hydrogen atom from the 2- or 4-position of an aromatic 6-membered heterocyclic compound in which the 1-position is occupied by a nitrogen atom and R2 is an organic radical.  The lactam may be a saturated or unsaturated ring containing at least 4 carbon atoms which may be substituted with hydrogen or hydrocarbon radicals, or 2 lactam rings joined by an alkylene bridge, and may be in particulate form optionally covered with an inert coating which is dissolved or melted before reaction. Lactams specified include e -caprolactam.  Catalysts may be metal compounds having a pK value greater than 6. Those specified include potassium caprolactam salt which may be prepared in situ.  0.01-10% may be used.  The promoter may be prepared from an ester or halide of carbonic acid together with R1OH or an ether thereof.  The latter may be a 5-, 6- or 7-membered heterocyclic compound which may contain another hetero-atom in addition to nitrogen.  R2 may be the same as R1 or may be a C1- 18 alkyl group or a saturated or unsaturated, mono- or di-nuclear carbo- or heterocyclic group, e.g. a C1- 12 cycloalkyl or an aralkyl group.  Promoters specified include <FORM:1057782/C3/1> and the corresponding compounds in which the ethyl group is replaced by Me, Prn, Bun, n-pentyl, Hexn, Ph and cyclohexyl and <FORM:1057782/C3/2> <FORM:1057782/C3/3> <FORM:1057782/C3/4> <FORM:1057782/C3/5> <FORM:1057782/C3/6> 0.0001-5% may be used, the ratio of gm. atoms of metal in the catalyst to moles of promoter being 0.1-20:1.  Other additives may also be used including colloidal SiO2, and fibrous reinforcing agents ethylenic monomers, ethylene oxide, HCHO, isocyanates, and anionically polymerized addition polymers.  The reaction may be carried out in a solvent for the monomer and/or the polymer, and those specified include hydrocarbon polymers and dimethyl formamide.  The products may be mixed below the reaction temperature and may be between 25 DEG C., and the decomposition temperature of the product which may be above 300 DEG  C.  The pressure may be atmospheric or below or above. Whilst O2 may be present, active hydrogen, e.g. water, should be absent in the earlier stages of reaction and so a dry air or dry N2 atmosphere may be used. Energy may be supplied by conduction, radiation, direct contact with hot gases, dielectric heating, ultrasonics, ionizing radiation or microwaves.  The catalyst and promoter may be added simultaneously or consecutively or a mixture of catalyst and lactam may be added to one of promoter and lactam at a lower temperature.  The reaction may be continuous to give a homo- or copolymer and should be stopped when the reduced viscosity of the mixture is 1.25 decilitres/gm.  In particular, embodiments (1) the catalyst or promoter may be localized in the mixture, e.g. in the surface to give non-uniform polymerization, (2) a mixture of xylene, cellulose pulp and metallic Na is treated with e -caprolactam in dimethylformamide containing a promoter, (3) the lactam and catalyst are extruded into a bath containing promoter and (4) the polymerization is carried out in the pores of foamed metals, ceramics, high melting organic materials, fibrous materials, leather, paper, woven and non-woven fabrics and batting.  The product may be mixed with other polymers, examples of which are given, washed e.g. with aqu NH4 acetate, foamed, using a solvent as blowing agent, moulded in a closed mould or by extrusion, injection or rotational moulding, to give fibres, films, fibrils and materials for laminates, paper making, coating and sintering.  Reference has been directed by the Comptroller to Specification 945,218.