Patent GB-762938-A (GB)
Title: Silk sutures and ligatures
IPC: A61L17/14
Filed: 1954-12-14
Abstract: A homopolymer or copolymer of a methacrylic acid ester or esters of the general formula CH2.C(CH3)COOR in which, in the case of a homopolymer, R is an alkyl radical having three to six carbon atoms and, in the case of a copolymer, R is two or more alkyl radicals, neither of which has more than twelve carbon atoms, the average number of carbon atoms in the R groups in the copolymer being three to six, is used to impregnate and coat a silk strand (see Groups IV (c), VI and XI).  A copolymer of one of the following pairs of esters of methacrylic acid, methyl and n-hexyl, ethyl and n8hexyl, methyl and n-octyl, methyl and n-lauryl or ethyl and n-octyl or of monomeric n-butyl methacrylate and monomeric n-hexyl methacrylate or a homopolymer of n-hexyl ester of methacrylic acid is prepared by slowly introducing the chosen esters from which any hydroquinone has been removed by washing in sodium carbonate-sodium hydroxide aqueous solution, into a mixture of sodium lauryl sulphate and benzoyl peroxide in water.  After polymerization is completed, the entire mixture is passed into methanol at room temperature to coagulate the polymer, which is squeezed dry and extracted in boiling methanol.ALSO:A silk thread or strand is impregnated under reduced pressure with a solution in an organic solvent of a homopolymer or copolymer of a methacrylic acid ester or esters of the formula CH2:C(CH3)COOR, in which, in the case of a homopolymer, R is an alkyl radical of 3-6 carbon atoms and, in the case of a co-polymer, R is an alkyl radical which has not more than 12 carbon atoms, the average number of carbon atoms in the R groups in the copolymer being 3-6; the strand is then heated to remove most of the solvent and passed through a heated die.  The strand may be immersed in a solution in toluene of the polymer (see Group IV(a)) under a pressure not greater than 1 mm. of mercury, and, after excess solution has been removed, the strand may be drawn through a vertical preheating column at a temperature of 200 DEG C. to render the polymeric substance semi-fluid and remove a substantial amount of the toluene.  The strand may then be passed through a funnel-shaped aperture in a stainless steel die maintained at a temperature of 250 DEG C.-300 DEG C. (see Group IX).  The diameter of the aperture does not exceed the diameter of the strand by more than 1 mil.  On leaving the die the strand is passed through a baking column maintained at a temperature of 130 DEG C.-150 DEG C. and wound on a spool.  Alternatively the strand may be repeatedly impregnated and air-dried after the removal of excess solution.ALSO:A non-capillary silk suture comprises a silk suture strand impregnated and coated with a homopolymer or copolymer of a methacrylic acid ester or esters of the general formula CH2 : C(CH3) COOR in which, in the case of a homopolymer, R is an alkyl radical having three to six carbon atoms and, in the case of a copolymer, R is two or more different alkyl radicals, neither or none of which has more than twelve carbon atoms, the average number of carbon atoms in the R groups in the copolymer being three to six.  A silk suture is coated and impregnated with a solution in an organic solvent of a homopolymer or copolymer of methacrylic acid ester of esters (see Group IV(a)).  After removing the solvent by heating, the suture is drawn through a tunnel-shaped aperture (see Group IX), the diameter of which does not exceed the diameter of the silk thread used by more than one mill. and then baked.  The suture is impregnated with 2 per cent to 12 per cent by weight of homopolymer or copolymer.  Such a suture is non-capillary, does not broom when cut and has good knot-holding properties.