Patent GB-1446487-A (GB)
Title: Radiation-shielding textile articles and their preparation
IPC: G21F1/10
Filed: 1973-12-28
Abstract: 1446487 Movolak filaments KANEBO Ltd 28 Dec 1973 [29 Dec 1972] 60042/73 Heading B5B [Also in Divisions C3 and D1] Textile articles having radiation-shielding properties comprises phenolic resin fibres whose sole or main constituent (present in amount of at least 70% wt.) is a cured novolak resin whose degree of cure is 5-30%, containing 0À1-4 milli-equivalents/gram of fibre of sulphonic acid groups and which contain chemically bonded to such acid groups atoms of metals of atomic number at least 13, e.g. Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Pd, Zr, Sb, Ti, Cd, Ba and Pb, generally in an amount of 0À1-3À5 milliequivalents of the metals per gram of fibre. The textile articles may be of continuous filaments, staple fibres, yarns, woven or knitted fabrics, non-woven fabrics, felts or mats. The fibres may contain 0À1 to 30% wt. of a fibre-forming thermoplastic synthetic resin, e.g. a polyamide, polyester, polyolefin, polyurethane or polyesterether. The textiles may be prepared by curing the uncured fibres with a curing agent, sulphonating the cured novolak resin in the fibres and then converting the sulphonic acid groups either directly or via an alkali metal salt thereof into the salt of the metal of At. No. at least 13 by reaction with an aqueous solution of a salt of the said metal. The fibres may be prepared by melt or jet-spinning. The fibres may be cured using an aqueous or aqueous-organic solvent solution of the curing agent and an acidic or basic catalyst or by treatment with the vapour of the curing agent. Suitable curing agents are formaldehyde, paraformaldehyde, furfural, chloral, glyoxal, hexamethylenetetramine, trioxane, tetraoxane and polyoxymethylene. The curing treatment may take place in 2 stages. The fibres may be reacted either prior to spinning or before or during the curing treatment with a nitrogen containing compound of the formula Y = C-(NR 1 R 2 ) 2  where Y is oxygen, sulphur or -NH, and R 1  and R 2  each represent a hydrogen atom, a hydroxyalkyl or alkoxyalkyl group, or R 1  and R 2  taken together may form an alkylene group; or with melamine, acrylamide, acrylthioamide, N-methylolaerylamide or -acrylthioamide, dicyandiamide, triethylene tetramine, polyethyleneimine or piperazine. The sulphonic acid group may be introduced either directly into the phenolic nucleus or to the methylol or phenolic OH groups using concentrated sulphuric acid, oleum, chlorosulphonic acid, sulphur trioxide, sulphuryl chloride, an aminosulphonic acid, e.g. taurine or an alkali metal salt thereof, or an hydroxy sulphonic acid, e.g. isethionic acid. The metal salt solutions are preferably the nitrates, carbonates, halides or hydroxides of Pb, Cd or Ba. The treating solutions at each stage, i.e. curing, sulphonation and introduction of the metal ion may be aqueous or aqueous organic solvent solutions, the solvent preferably being one which swells the fibres, e.g. dioxane, acetone, methyl ethyl ketone, benzene, toluene, xylene, dimethylformamide and dimethylacetamide. The textiles shield against alpha and beta rays. In Example 1 phenol-formaldehyde novolak resin filaments in tow-form are cured using an aqueous solution of HCHO and HCl, and are then spun and woven into a fabric. The fabric is then sulphonated by immersion in fuming H 2 SO 4  and converted to the Na salt using Na 2 SO 4 , and then treated with an aqueous solution of lead nitrate. In Example 2 the novolak filaments of Example 1 are partially cured using an aqueous solution of HCl and HCHO and then further cured using a liquor comprising urea, methanol, HCl and HCHO, and then sulphonated using concentrated H 2 SO 4  and dimethylacetamide, then reacted with NaOH and then with aqueous lead nitrate. The resulting filaments were cut to fibres of 2 inches length, made into a non-woven fabric and hot-pressed to form a sheet. In example 3 novolak filaments are partially cured as in Example 2 and then further cured using aqueous NH 3  and HCHO, then sulphonated using aqueous N-methyltaurine, then reacted with NaOH and then with aqueous cadmium chloride. A non-woven cloth was then prepared as in Example 2. In Example 4 a novolak resin fibrous material having a fibre length of not more than 2 microns is cured as in Example 1 and the resulting filaments dispersed in an aqueous resole and formed into a paper-like sheet which is treated with fuming H 2 SO 4 , then NaCl and then with aqueous lead nitrate. In Example 5 filaments melt-spun from a mixture of a novolak resin and nylon 12 are cut to a length of 2 inches and cured as in Example 1 and then formed into a woven fabric which was then treated with fuming H 2 SO 4 , NaOH and then aqueous lead nitrate.