Patent GB-700608-A (GB)
Title: Polymeric products derived from polyisocyanate-modified polyesters
IPC: C08G18/76
Filed: 1950-01-11
Abstract: Elastomeric products are obtained by reacting an anhydrous linear polyester, which may contain a small number of amide groups, of hydroxyl number between 20 and 80 with diisocyanate in an amount in an excess of 20 - 250 per cent. of that required to react with the hydroxyl groups of the polyester, mixing the thus modified polyester with a glycol and reacting the glycol with the modified polyester while moulding the mixture.  The quantity of glycol used is such that the isocyanate groups remaining after reaction with the glycol represent an amount of diisocyanate equal to at the most 4 per cent. of the weight of the initial polyester. The polyester is derived in the main from saturated aliphatic acids but small proportions of aromatic and unsaturated acids may be used.  The polyesters may be derived from hydroxy acids. Preferably the diisocyanate is aromatic, e.g. 1.5 naphthalene dichlorodiphenyl dichlorobenzidine and nitrobenzidine diisocyanates and the diisocyanates of the pyrene, fluorene and chrysene series.  The glycols are preferably the butane, butene or butine diols, and cyclic diols such as quinitol and the hexahydrocatechols.  Glyceryl a  - monochlorohydrin, glyceryl a  - alkyl ethers or a  - aryl ethers, xylylene glycols and the adduct of butene diol and anthracene are also referred to.  To avoid anomalous behaviour the initial polyester may be washed with water or blown with an inert gas.  The initial reaction with diisocyanates may be delayed by the use of acid reacting substances, e.g. hydrogen chloride, sulphur dioxide, boric acid and activated charcoal prepared in an acid medium.  The glycol reaction can be accelerated by adding tertiary amines, e.g. pyridine, hexahydrodimethylaniline, methyl piperidine, dimethyl piperazine, tribenzyl amine and tetramethyldiamino dipropylether. Basic reacting groups in the polyester itself have a similar action.  Dyestuffs, plasticizers, e.g. methylene - bis - thioglycollic acid butyl ester, phthalates and sulphonamides, and fillers, e.g. titanium dioxide, calcium silicate and carbon black, may be incorporated at any stage.  Titanium dioxide and carbon black as fillers improve the mechanical properties.  The products may be compression moulded, cast, extruded or calendered. Scrap material may be reclaimed by sheeting on a roller preferably with a plasticizer, e.g. modified or unmodified polyester, or by heating with steam and blending with freshly condensed material or diisocyanate.  The products may be used for making bottle rings, bicycle handles, foot rests, bandages, tyres, packings, coated fabrics, belts, plates, pipes, buffers, cylinders, rings, boot and shoe parts, balls, machine parts, and coverings for ball mills and classifying apparatus.  In examples a glycol adipic acid or propylene glycol adipic acid polyester or a mixture of these is reacted with (1) 1.5 naphthalene diisocyanate and quinitol, the product being sheeted on a roller and moulded at 150 DEG C. for 20 minutes; the properties of the unfilled material and one filled with carbon black are compared: (2) naphthalene diisocyanate and (a) thiodiethylene glycol, (b) 1.4 butine-diol, the material being suitable for conveyer belts: (3) naphthalene diisocyanate and triethylene glycol, the product being used to coat cotton and polyurethane fabrics: (4) naphthalene diisocyanate and 1.4 butene-diol, the mixture being cast into a mould and heated at 100 DEG C. for several hours: (5) naphthalene diisocyanate and quinite, the initial polyester containing carbon black and the product being cast into a bicycle tyre: (6) naphthalene diisocyanate and quinite, hydrochloric acid being added to the initial polyester and hexahydromethylaniline before the quinite reaction, the product being cast into a tyre: (7) nitrobenzidine diisocyanate and quinite; (8) o - dichlorobenzidine diisocyanate and (a) quinite, (b) 1.4 butene diol: (9) various quantities of naphthalene diisocyanate and quinite, the mechanical properties of the various products being compared: (11) naphthalene diisocyanate and quinite, the initial polyester containing carbon black and butadiene sulphone (retarder) and paraffin (mould lubricant) being added before the isocyanate reaction; the product is extruded to form an inner tube: (12) naphthalene diisocyanate and butane diol, the initial polyester containing carbon black and montan wax being added with the diol; the product is extruded to form water hose.  (13) naphthalene diisocyanate and a mixture of butane diol and glycerine a  - phenylether, the polyester containing carbon black and paraffin and hydrochloric acid being added before the isocyanate reaction; the product after mixing with esterified fatty acids (lubricant) is extruded; (14) naphthalene diisocyanate and (a) quinite, (b) butane diol, the diol being added to a solution of the modified polyester in methylene chloride, benzene or acetic acid ester and the solution being used to make dipped articles; the initial polyester contained hydrochloric acid: (18) naphthalene diisocyanate and quinite, the proportions being chosen to give a product leathery at room temperature but rubbery at 60 - 80 DEG C. In example (10) a hexanediol adipic acid polyester is reacted with naphthalene diisocyanate and then with hexanediol.  Examples (15), (16) and (17) describe the reclamation of scrap (a) from a tyre made as in example (5) by mixing with a small proportion of a glycol phthalic acid polyester; (b) from a propylene glycol adipic acid polyester modified with naphthalene diisocyanate and hexahydrocatechol and containing carbon black by mixing with an incompletely cured product from the same reactants; (c) by heating the scrap under steam pressure (4 - 15 atmospheres) for 30 - 90 minutes, and if desired, incorporating naphthalene diisocyanate and butylene glycol.  It is also stated that scrap may be reclaimed by mixing with scrap from polyester rubbers cured by reaction with water or hydrogen sulphide.  The Specification contains a discussion of the prior art as disclosed in B.I.O.S. Final Report No. 1166. Specification 553,733 is referred to.ALSO:Wheel tyres are moulded from diisocyanate modified polyesters cured by reaction with glycols during moulding, by casting the liquid material into a mould rotating, e.g. at about 200 r.p.m. Either a flat structure or the finished tyre shape can be produced, using a metal core with or without textile or metal reinforcement.  For reinforced tyres the material can be cast on to textile or metal nettings or cords or the reinforcement worked into the cast tread.  Flat structures are subsequently shaped before final curing on a straining tube or metal core.  The Specification also refers to the use of the following substances as mould lubricants or release agents when moulding isocyanate modified polyester rubbers:-waxes, silicones, and inert water soluble films, e.g. of water soluble cellulose derivatives.