Patent GB-535336-A (GB)
Title: Manufacture of films and the like
IPC: G02B5/30
Filed: 1939-10-02
Abstract: 535,336. Resinous condensation products ; dyes; polarizing films. DU PONT DE NEMOURS & CO., E. I. Oct. 2, 1939, No. 27004. Convention date, Sept. 30, 1938. [Classes 2 (iii) and 15 (ii)] [Also in Group XX] Polarizing transparent films are prepared by incorporating in a superpolyamide film a finely divided polarizing agent incompatible therewith, the film being oriented, for example by cold drawing or cold working preferably subsequent to the incorporation of the polarizing agent. Suitable polarizing agents are asymmetric di-chroic crystals of size below 100 Á anisotropic transparent finely-divided crystals having a high degree of asymmetry and a plurality of indices of refraction, colloidal assymonotric metal particles and water soluble azo-dyestuffs such as herapathite, aragonite, bismuth (by decomposition of bismuth tartrate), Pontamide Navy Blue DB, quinine iodo sulphates, calcite, tourmaline, penninite, sassolite, crystals of strontium carbonate, barium carbonate, lithium carbonate, potassium carbonate, potassium thiocyanate, sodium thiocyanate, triiodo-benzene, aminoacetic acid, hydrated codeine, o-acetylsalicylic acid, cinchonine, hydrocarbostyril, 1:3: 5-triphenylbenzene, picramic acid, benzene-1 : 2 : 3 - tricarboxylic acid, phenylbiuret, theobromine salicylate, 4-4<SP>1</SP>-difluoro-2-nitrodiphenyl, diphenylmaleic anhydride, potassium acid phthalate, magnesium 1 : 5-naphthalene di-sulphonate hexahydrate, antipyrine, potassium picrate, isohydroxydimethyluric acid, hexamethylbenzene, tellurium, arsenic, antimony, silver, platinum and gold, Pontamine Blue CLG. Suitable superpolyamides include polytetramethylene adipamide, sebacamide, and suberamide, polypentamethylene sebacamide, polyhexamethylene adipamide, #-methyladipamide, and sebacamide, polyoctamethylene adipamide, polydecamethylene adipamide and p-phenylene diacetamide, poly-p-xylylene sebacamide, polyamides derived from aminocarboxylic acids or their lactams such as 6-aminocaproic acid, caprolactam, 9-aminononanoic acid and 11- amino undecanoic acid. The polarizing agent may be added to the molten superpolyamide with a solution thereof or to the materials to be polymerized ; the agent may be prepared in the presence of the polymer; the agent may be incorporated, for example by dyeing, with the formed polymer. In examples (1) a co-polyamide (derived from hexamethylenediammonium adipate and decamethylenediammonium sebacate) is dissolved in methyl ethynyl carbinol blended with hexapathite and cast into films the film being subsequently stretched ; (2) . molten polyhexamethyleneadipamide is blended with aragonite and extruded through rolls into cold water to yield a film ; (3) a polyhexamethyleneadipamide film is immersed in an alkaline solution of bismuth tartrate, then treated with a mixture of sodium hydroxide and formaldehyde, the final film being colddrawn : (4) a polyhexamethyleneadipamide film is immersed in a bath of a dyestuff prepared by coupling one mol. of tetrazotized benzidine in acid solution to one mol. of H-acid, coupling the product in alkaline solution with one mol. of diazobenzene and the resulting compound is coupled to one mol. of 1-naphthol- 4-sulphonic acid, the dyed film being dried and cold-drawn. The products, alone or laminated with glass, may be used in the manufacture of automobile headlamps, windshields, windows, eyeglasses, goggles, sunglasses, camera lenses, demonstrating apparatus, examining apparatus for jewels in microscopes and in mirrors. U.S.A. Specifications 1,918,848, 2,078,254, 2,123,901 and 2,123,902 are referred to.