Patent GB-593547-A (GB)
Title: Compositions comprising cellulose derivatives and n-alkoxy methyl polyamides
IPC: C08L1/08
Filed: 1945-06-04
Abstract: Solutions of organic cellulose derivatives modified by N-alkoxymethyl polyamides or N-alkyl-thiomethyl polyamides from which clear, transparent films may be cast or filaments, tubes or ribbons may be extruded, are obtained by forming the N-alkoxymethyl- or N-alkylthio-methyl polyamides in situ by reacting a synthetic linear polyamide with formaldehyde and an alcohol or mercaptan in the presence of an acid catalyst, an organic cellulose derivative and a mutual solvent or solvent mixture.  As the cellulose derivative which preferably contains free hydroxyl groups, numerous esters, mixed esters and ethers of cellulose are specified.  Numerous types of suitable polyamides and interpolyamides are also specified.  The preferred solvent is glacial acetic acid which also functions as an acid catalyst, but other specified solvents which, if desired, may be employed in admixture are formic acid, acetone, methanol, ethanol, chloroform, methylene chloride, dioxane and dimethyl formamide. Formaldehyde may be replaced by a formaldehyde liberating substance. The alcohol has preferably less than 8 carbon atoms such as methanol, ethanol, propanol, butanol, isobutanol, dimethyl carbinol or ethylene glycol.  When an N-alkyl-thiomethyl polyamide is to be formed, a mercaptan, e.g. ethyl, butyl or allyl mercaptan, ethanedithiol, 1-thiosorbitol, or mercaptoacetic acid, replaces the alcohol.  If desired, the polyamide and the reactants may be added to an esterification solution containing a newly-formed cellulose ester. Alternatively, the cellulose derivative and the polyamide may be dissolved in separate miscible solvents and the solutions mixed before the reactants are added.  If a non-acidic solvent is used, an acid catalyst, e.g. chloracetic, a -chlorpropionic, citric, dichloracetic, formic, fumaric, lactic, maleic, malic, phosphoric, phthalic, salicylic or tartaric acid must be added to the solution before the alkoxymethyl polyamide can be formed.  The solution may be cast directly into films or wet- or dry-spun into filaments. Alternatively, the modified cellulose derivative may be precipitated from solution by the addition of e.g. water or aqueous acetic acid, washed, dried and redissolved in a solvent such as chloroform, chloroform - methanol, dioxane - methanol, nitromethane, nitromethane-methanol, methylene chloride, methylene chloride-methanol, diacetone or dimethylformamide, this solution being then formed into filaments or films.  The filaments or films may be insolubilized by heating at a temperature of 125 DEG  to 135 DEG  C.  If, however, an acid catalyst is added to the solution from which the articles are obtained or if the finished articles are treated with an aqueous solution of an acid catalyst, then the insolubilization temperature may be considerably reduced.  The modified cellulose derivative, e.g. cellulose acetate-N-alkoxymethyl polyamide, may be treated before or after insolubilization with, e.g. an aqueous solution of ammonium acetate and ammonia, sodium acetate and sodium hydroxide, alcoholic alkali or with a methanolsodium methylate solution to saponify the cellulose acetate.  In examples: (I) a glacial acetic acid solution of cellulose acetate at 70 DEG  C. is added to a glacial acetic acid solution of an interpolyamide of hexamethylene diammonium adipate and hexamethylene diammonium sebacate.  The mixture is stirred and a 1 : 1-methanol : formaldehyde solution added.  The reaction proceeds at 70 DEG  C. and the solution is cast into a film.  (II) The reaction mixture of example (I) is cooled to 5 DEG  C. and extruded into an aqueous coagulating bath of glacial acetic acid and ammonium acetate at 5 DEG  C. to produce filaments. (VII) A solution of cellulose acetate in glacial acetic acid at 70 DEG  C. is added to a solution of an interpolymer of hexamethylene adipamide and hexamethylene diammonium sebacate in glacial acetic acid.  The mixture is stirred and a 1 : 1-methanol : formaldehyde solution added.  The reaction proceeds at 70 DEG  C., the solution cooled by the addition of aqueous acetic acid and the diluted solution poured into water to precipitate the product.  The product is washed, dried, dissolved in chloroformmethanol or dioxane-methanol and the solution, to which plasticisers, e.g. dibutyl phthalate or tricresyl phosphate may be added, is cast into films or dry spun into filaments.  In another example, a plasticiser such as methyl phthalyl ethyl glycolate is added to the reaction mixture of example (I).  In another example, the polyamide employed is an interpolymer of hexamethylene diammonium sebacate, hexamethylene diammonium adipate and 6-caprolactam, and in another example a glacial acetic acid solution of cellulose acetate is added to a formic acid solution of polyhexamethylene adipamide.  In other examples, the cellulose derivative employed is cellulose acetate-butyrate, cellulose acetate-propionate, or ethyl cellulose. In a further example, the film obtained as in example (VII) is deacetylated by immersion in an aqueous bath of ammonium acetate and ammonia.  Specifications 461,236, 461,237, 540,134 and 557,544 are referred to.