Patent GB-875131-A (GB)
Title: Improvements in or relating to modified synthetic addition polymers
IPC: D06M14/28
Filed: 1957-10-03
Abstract: Synthetic addition polymers are contacted with one or more polymerizable monomers containing reactive non-aromatic carbon-to-carbon unsaturation and acid or acid salt groups (or functional groups which are subsequently converted to acid or acid salt groups) during or after irradiation with particulate or electromagnetic high energy ionizing radiation.  By "acid group" is meant a group capable of forming a metal, amine or ammonium salt. Examples of such monomers are carboxylic acids, such as acrylic, methacrylic, maleic, itaconic, furoic, propiolic, fumaric and dichloromaleic acids preferably having up to 5 carbon atoms though acids having up to 20 carbon atoms may be used; salts thereof, e.g. calcium, sodium, potassium and ammonium or amine salts; and derivatives thereof, e.g. acid chlorides, anhydrides, half acid esters, half acid amides or esters, nitriles, aldehydes or ketones; sulphonic acids (styrene or ethylene sulphonic acids): alkyl or aralkyl acid phosphates, phosphites, phosphonates and phosphinates; acid alkyl sulphates and carbonates.  In a modification of the process acidic chain transfer agents, e.g. thioglycollic acid, chloropropionic acid and chloroethanesulphonic acid may be used in place of the monomer.  A mixture of monomers may be employed or a second monomer may be applied and grafted subsequently to the first. The polymer may be in the form of fibres, films or pellicles, woven, knitted or felted fabric, bristle or artificial straw.  Where the article is thick a surface treatment only is effected.  Polymers referred to are those derived from such monomers as styrene, acrylic esters, vinyl chloride, vinyl fluoride, vinylidine chloride, vinyl acetate, vinyl ketones, vinyl ethers, divinyl ether, the halogen, sulphur-, nitrogen-, or phosphorus-containing vinyls, the vinyl silanes, ethylene, tetrafluoroethylene, propylene, the allyl esters, acrylonitrile, methacrylonitrile, 1, 3-butadiene, isoprene, chloroprene and 2, 3-dimethyl-1, 3-butadiene.  The monomer may be applied to the polymer by melt coating or padded on as a dispersion, solution, pure liquid or emulsion; an article may be sprayed or dipped in a liquid; the monomer may be added as a vapour; or the monomer may be added to a melt or solution of the polymer before shaping, e.g. by spinning.  Radiations employed include electrons, nuclear particles such as protons, neutrons, a -particles, b -particles and deuterons and X-rays produced by irradiating a metal, e.g. a gold or tungsten target with electrons.  In the examples, accelerated electrons are employed. The preferred dose is at least 0,01 Mrep: it should be sufficient to graft at least 200 equivalents of titratable acid groups per 106 grams of polymer.  Where the irradiation is conducted before contacting it is preferred to maintain the temperature during irradiation and before contacting to below room temperature preferably below 0 DEG C. and to employ an inert gas atmosphere or vacuum during irradiation; where irradiation takes place in the presence of the acid, room temperature or high temperatures e.g. 100 DEG -160 DEG C. may be used.  With such temperatures it is desirable to exclude oxygen.  Subsequently to formation of the graft polymer, the free acid may be converted to the salt form e.g. by contacting with a solution of the salt of the desired cation, e.g. sodium, calcium, lithium, ammonium, or amine, with a weak acid: when using a solution containing more than one ion, one ion may be picked up selectively and the sequestrant for this ion may permit a second to form the salt; if desired after incorporating one ion (sodium) in the graft polymer a second ion (calcium) may be attached near the surface.  In the examples, polyvinyl chloride, polyethylene and polyacrylonitrile samples are soaked in aqueous acrylic acid, irradiated, washed and treated with sodium carbonate solution.  The product may have greater resistance to hole melting, greater receptiveness to basic dyes, increased resistance to flash heat and higher zero strength temperature, a high degree of elasticity and heat deformability and the elastic modulus may be increased especially by keeping the structure under tension during grafting.  Fabrics formed of grafted polymers having acid groups neutralized with sodium salts have an improved degree of crease recovery, requiring only to be wet and hung up to dry.  Some of the products having salt groups, when subjected to heating show high shrinkage and by using yarns of modified and unmodified polymer in the same fabric, by applying the unsaturated acid or metal ions in a pattern or by shielding parts of the structure during the grafting, textured effects may be achieved.  The subject-matter of Specifications 758,735, 845,897 and 845,898 is disclaimed. Specifications 801,531 and 809,558 also are referred to.  Reference has been directed by the Comptroller to Specifications 801,528 and 809,838.ALSO:The properties of synthetic addition polymers and of yarns and textiles produced therefrom are modified by contacting said polymers with polymerizable monomers containing non-aromatic carbon-to-carbon unsaturation and acid or acid salt groups (or functional groups which are subsequently converted to acid or acid salt groups) during or after irradiation with particulate or electromagnetic high energy ionizing radiation (see Group IV(a)); in a modification the monomer is replaced by an acidic chain transfer agent.  The polymer may be in the form of fibres, films or pellicles, woven, knitted or felted fabric, bristle or artificial straw.  The products may have a greater resistance to hole melting, greater receptiveness to basic dyes, increased resistance to flash heat and higher zero strength temperature, and a high degree of elasticity and heat deformability, and the elastic modulus may be increased, especially by keeping a structure under tension during grafting. Fabrics formed of grafted polymers having acid groups neutralized with sodium salts have an improved degree of heat recovery, requiring only to be wet and hung up to dry.  Some of the products having salt groups, when subjected to heating, show high shrinkage, and by using yarns of modified and unmodified polymer in the same fabric, by applying the unsaturated acid or metal ions in a pattern or by shielding parts of the structure during the grafting, textured effects may be achieved.  The subjectmatter of Specifications 758,735, 845,897 and 845,898 is disclaimed.  Specifications 809,558 and 801,531 also are referred to.  Reference has been directed by the Comptroller to Specifications 801,528 and 809,838.