Patent GB-585859-A (GB)
Title: Adhesive compositions
IPC: C08J5/06
Filed: 1944-12-20
Abstract: The adhesive obtained by treating an isoprene polymer dissolved in a solvent with an organic polyisocyanate and heating the resultant cement till the viscosity is reduced by not less than 20 per cent (for the method of preparation see Group V) is used to bond textiles such as cellulose esters and ethers and regenerated cellulose and wool and nylon to an elastomeric stock which may be natural rubber, guttapercha or balata or synthetic rubber. Examples are given of the treatment of regenerated cellulose with this adhesive in the manufacture of tyres and of cotton duck in the preparation of plied belting.  The isoprene polymer may be natural or synthetic rubber, balata or guttapercha.ALSO:An adhesive suitable for bonding textiles, wood, leather and metal to elastomeric stock comprises treating an isoprene polymer dissolved in a solvent with an organic polyisocyanate and heating the resultant cement until the viscosity has been reduced by not less than 20 per cent.  The isoprene polymer may be pale crepe or smoked sheet natural rubber, gutta-percha, balate or synthetic polymers of isoprene.  Examples are given in which the polyisocyanate is methylene-bis-(4-phenyl-isocyanate) or hexamethylene diisocyanate; other such compounds which may be used include alkylene diisocyanates such as ethylene-, propylene-1 : 2-, butylene 1 : 2- and butylene 2 : 3-diisocyanates; cycloalkyline diisocyanates such as cyclohexylene 1 : 2-diisocyanate; polymethylene diisocyanates such as trimethylene-, 2-chlorotrimethylene-, tetramethylene-, 2 : 3-dimethyltetramethylene-, pentamethylene-, decamethylene-, and dodecamethylene-diisocyanates; aromatic diisocyanates such as metaphenylene-, paraphenylene-, 1 methylphenylene 2 : 4-, 5-nitro-1 : 3-phenylene; and naphthylene-1 : 4-diisocyanates; and aliphatic aromatic diisocyanates such as xylylene diisocyanates containing substituents such as OCH-CH2-O-CH2NCO, OCNCH2CH3-O-CH2CH2-CNO and OCN(CH2)3-S-(CH2)3NCO; and also compounds of the general formula R(NCO)n where R is a polyvalent organic radical and n is an integer larger than 1.  The isoprene polymer is first dissolved in a dry organic solvent such as xylene, carbon tetrachloride, benzene, gasoline, ethylene dichloride, chlorobenzene or kerosene, preferably with the addition of a peptizing agent which may be an aromatic mercaptan such as thio-alpha naphthol, and agitated for some hours either at ordinary temperatures or at a temperature up to 142 DEG C.  The polyisocyanate is then added and the mixture heated at a temperature of 75-250 DEG C. in an open vessel or in an autoclave for a further period of not less than 24 hours till the desired reduction in viscosity is obtained.  The quantity of polyisocyanate may be from 0.5 to 95 per cent. of the weight of the elastomer, the preferred range being 5-25 per cent, The finished adhesive is used in a concentration of 1-50 per cent, The adhesive may be applied to the yarn, cord or fibre of rayon, wool, nylon, cotton, regenerated cellulose, or cellulose esters or ethers, or to wood, leather or metal by means of a dipping tank, rolls or by coating, and the treated material then caused to adhere to the elastomic material which may be natural rubber, gutta percha or balata, or polymers of isoprene butadiene and chloroprene, such as those made according to Specification 529,839 or interpolymers of these monomers with other polymerizable substances.  In the manufacture of belting, cotton duck was bonded to a friction stock comprising rubber, zinc oxide, stearic acid, pine tar, carbon blacks, reclaimed rubber, para cumarone resin, "Gilsonite" (Registered Trade Mark) and accelerators and antiagers, and then to a carcass stock which is free from carbon black.  Specification 574,903 also is referred to,