GB860992A - Method for improving materials containing cellulose fibres and products produced from such materials - Google Patents

Abstract

Felted fibrous sheet materials containing cellulose fibres of the class consisting of the fibres of rags, sulphate or sulphite cellulose are stabilized against the influence of moisture by exposing them at a temperature of 100-250 DEG C. to an atmosphere containing ketene or a polymer, e.g. diketene, or lower homologue thereof of the formula R1R2C = C = O, in which R1 and R2 are hydrogen or alkyl radicals having one to three carbon atoms inclusive, the total number of carbon atoms in R1 and R2 not exceeding four; the felted materials thereby retain their fibrous form and increase in weight by chemical reaction of the constituents with the ketene. The fibrous sheet material is preferably allowed to take up 2-75% of its weight of ketene or an equivalent amount of the polymer or lower homologue thereof. The ketene may be used in its pure form diluted with an inert gas, e.g. nitrogen or carbon dioxide, or in a partiallypurified form, as when produced by the pyrolysis of acetone, when it will contain methane and also possibly unconverted acetone. The fibrous sheet material need not be completely dry at the beginning of the treatment since, in the case of ketene, the moisture will only give rise to the production of acetic acid, which reacts with fresh ketene to form acetic acid anhydride which acts as an acetylating agent in a manner similar to ketene. The fibrous sheet materials may consist wholly of cellulose fibres but may also contain animal fibres, e.g. wool, and may be in the form of felt, paper, cardboard, sheets or boards. Felt for bituminous roofing and insulating materials may p be treated. Specification 237,591 is referred to.ALSO:Felted fibrous sheet materials containing cellulose fibres of the class consisting of the fibres of rags, sulphate or sulphite cellulose are stabilized against the influence of moisture by exposing them at a temperature of 100 DEG -250 DEG C. to an atmosphere containing ketene or a polymer, e.g. diketene, or lower homolgue thereof of the formula R1R2C=C=O, in which R1 and R2 are hydrogen or alkyl radicals having one to three p carbon atoms inclusive, the total number of carbon atoms in R1 and R2 not exceeding four; the felted materials thereby retain their fibrous form and increase in weight by chemical reaction of the constituents with the ketene. The fibrous sheet material is preferably allowed to take up 2-75% of its weight of ketene or an eq equivalent amount of the polymer or lower homologue thereof. The ketene may be used in its pure form diluted with an inert gas, e.g. nitrogen or carbon dioxide, or in a partially purified form, as when produced by the pyrolysis of acetone, when it will contain methane and also possibly unconverted acetone. The fibrous sheet material need not be completely dry at the beginning of the treatment since, in the case of ketene, the moisture will only give rise to the production of acetic acid. which reacts with fresh ketene to form acetic acid anhydride which acts as an acetylating agent in a manner similar to ketene. The fibrous sheet materials may consist wholly of cellulose fibres but may also contain animal fibres, e.g. wool. Felt for bituminous roofing and insulating materials may be treated. Specification 237,591 is referred to.