Patent GB-868651-A (GB)
Title: New forms of synthetic polymers and shaped structures therefrom and processes for their production
IPC: C08L77/00
Filed: 1958-01-22
Abstract: 868,651. Paper &c. made from synthetic filaments &c. DU PONT DE NEMOURS & CO., E. I. Jan. 22, 1958 [Jan. 23, 1957 (3); July 30, 1957 (2); Aug. 2, 1957], No. 2208/58. Class 96. Paper &c. which may be thick or thin, single or multiple-ply, absorbent, spongy, fluffy, feltlike, or dense, plain, and which may be surfaced as by brushing to form a nap, or e.g. as a basket weave, or moulded, or reinforced as by woven glass or nylon fabric, or resistant to acids, alkalies, fungi, or moulds, and may be used as tracing paper, artificial leather, electrical insulation &c., and which may include fillers, e.g. silica, sizes, dyes or wetting-agents &c., is made of " fibrids," i.e. non-rigid, synthetic polymer filaments, flattened tubes, or ribbon-like particles, which have been subjected to a vigorous agitation or other shearing and/or beating action whilst in the freshly precipitated or swollen condition, so that they have high water-holding capacity and will felt with each other and with other particles. The filaments &c. may be broken into small particles and drawn out by mechanical treatment. The " fibrids " preferably have one dimension not exceeding 10 microns, and interlock or felt together to give a wet strength of at least 0.017 lb. per inch per oz. per square yard. The synthetic polymers may be soft or hard, e.g. copolymers of acrylonitrile with methyl acrylate or vinyl chloride; polyacrylic and polymethacrylic esters, such as polymethyl methacrylate; polyvinylchloride and copolymers of vinyl chloride with vinyl esters, acrylonitrile, vinylidene chloride ; vinylidene chloride polymers; polyhydrocarbons, such as polystyrene and polyethylene; chlorosulphonated polyethylene; polychlorotrifluoroethylene; polyvinyl alcohol; partially hydrolysed polyvinyl esters; polyamides, such as polyhexamethylene adipamide, polyethylene sebacamide, polymethylene - bis - p - cyclohexylene adipamide, polycaproamide and copolyamides; polyurethanes; polyureas; polyesters, such as polyethylene terephthalate; polythiolesters; polysulphonamides; polysulphones, e.g. prepared from propylene and sulphur dioxide; polyoxymethylene; polyvinyl acetate; or their derivatives, e.g. halogenated polyhydrocarbons; aliphatic, aliphatic-aromatic, branched, carbocyclic, or heterocyclic polyamides and copolyamides, e.g. those prepared from aliphatic diamines such as ethylenediamine, propylenediamine, butylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, para-xylylenediamine, p-phenylene-diamine, p-cyclohexylenediamine, piperazine, benzidene and bis-p-aminophenyl-methane. Suitable dibasic acids which may be used as a starting-point for preparing polyamides include: oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, terephthalic, isophthalic, hexahydroterephthalic, p-phenylenediacetic, cyclohexylenedicarboxylic, p-benzenedisulphonic, 1,5-naphthalenedisulphonic, bibenzoic, bis-p-carboxyphenyl-methane, and long-chain dibasic acids, e.g. those derived from castor oil, N-alkylsubstituted copolyamides, e.g. obtained by reacting adipic acid with a mixture of hexamethylenediamine, N-isobutylhexamethylenediamine, or N,N<SP>1</SP>-isobutylhexamethylenediamine or copolymers prepared from ethylene glycol, terephthalic acid, and sebacic acid. Copolyester " fibrids " used may be aliphatic, aliphatic - aromatic, branched, carbocyclic, heterocyclic &c., e.g. those prepared from ethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, 1,5-pentanediol, pentaglycol 2,2 - dihydroxymethylpropane, 1,6 - hexanediol, para-xylene glycol, metaxylene glycol, hydroquinone, 1,6-cyclohexanediol, resorcinol, and bis-para-hydroxyphenylmethane, and from disulphonic acids, dicarboxylic acids or their derivatives. Of these, the dicarboxylic acids are preferred. Suitable dibasic acids for the copolyester " fibrids " are oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, terephthalic, isophthalic, phthalic, hexahydroterephthalic, p-phenylenediacetic, cyclohexylenedicarboxylic, p - benzenedisulphonic, 1,5 - naphthalenedisulphonic, bibenzoic, bis-p-carboxyphenylmethane, and long-chain dibasic acids, such as those derived from castor oil. The precipitant or the solution for forming the " fibrids " may contain additives, e.g. staple fibres, such as those from nylon, polyethylene terephthalate or polyacrylonitrile, and cellulose, glass fibres, asbestos, and/or dyes, antistatic agents, surfactants, fillers such as silica or titanium dioxide, pigments, antioxidants &c. The " fibrids " may be dried or shipped as a " filter cake," but are preferably formed and processed on a paper-making machine, e.g. using a flow-box with an opentopped flow-spreader 26, 27 and a delivery compartment 28 adjacent a travelling wirecloth 34 at an angle A of 20 to 45 degrees. A flexible film 30 may be draped over the upper part of the flow-box. In an example (6), a polyurethane with an inherent viscosity of 1.76 in 60/40 trichloroethane/phenol is prepared from 2,5-dimethylpiperazine and the bischloroformate of 1,4-cyclohexanediol. A solution containing 5.9% of this polymer, 3.8% of trifluoroacetic acid, 39.5% formic acid and 50.8% methylene chloride is added to approximately 300 ml. of water in a one-quart Waring Blender operating at full speed to produce " frazzled fibrids " approximately 5 microns in diameter. In another example (12) a flake formed from a polymer containing 20% polyhexamethylene adipamide and 80% polycaproamide is cut to pass through a # inch screen. A 15% solution with a viscosity of 150 centipoises is prepared by adding 50 lb. of this polymer to a mixture of 225 lb. of ethylene glycol and 28.3 lb. of water in a 50-gallon tank and stirring at 115‹ C. for 3¢ hours. The precipitant is prepared by mixing 108 gallons of ethylene glycol with 100 gallons of water and cooling to - 16‹ C. The precipitant, which has a viscosity of approximately 10 centipoises at this temperature, is fed into a tank with a 15-gallon hold-up at the rate of 3.54 gallons/minute. After 8-10 gallons have been added to the tank, addition of the polymer solution at a temperature of approximately 110‹ C. is started at a rate of 4.24 lb./ minute while addition of the precipitant is continued at the same rate.