US2243765A - Treatment of cellulosic textile materials - Google Patents

Description

latented May 27, 1941 UNlTED STATES "F @F TREATMENT OF CEILULOSIC TEXTILE MATERIALS Thomas Henry Morton, Braintree, England, ml-

signor to Courtaulds Limited, London, England,

a British company No Drawing. Application April is, 1940, Serial No. 330,425. In Great Britain April 4, 1939 3 Claims. (01. 260-:212)

This invention relates to the treatment of cellulosic textile materials with formaldehyde.

It is well known to treat cellulosic materials with formaldehyde with the object of obtaining yarious effects. For example, Eschalier in Brit ish Specification No. 25,647/06 has disclosed a process for strengthening cellulose threads, films and the like which consists in impregnating the formaldehyde and the acid catalyst before drying it, or subjecting it to any other dehydrating conditions.

In carrying out the processof this invention the proportion of the solution of formaldehyde to the cellulosemust be at least such that the cellulose is always in a fully swollen state. Generally it is preferred to have present however a considerably greater quantity of water than is necessary merely .to produce this swollen state.

The time and temperature of the treatment with the solution of formaldehyde and acid catalyst will vary with one another, the timerequired increasing rapidly as the temperature diminishes. The rate of absorption of formaldehyde by the cellulose will also depend upon the-concentration of the acid and of the formaldehyde in the treating solution.

Using a solution containing 40 per cent of formaldehyde and sulphuric acid sufllcient to give a normal solution the reaction is substantially complete in 10 minutes at 80 centlgrade;

washing and drying, the washing must be thorough and is preferably carried outfirst in cold and then in but running water, while the drying is preferably efiected at a temperature round about 100 centigrade.

' The cellulosic material may be in the form of cotton linters, bleached'wood pulp, or yarn or fabric prepared from natural or artificial fibres. The product obtained is difierent in many of its properties from that obtained by heating cellulose with formaldehyde and then dehydrating. For example, whereas it has 'been stated that when using Eschaliers process about 0.2 to 0.3 per cent of formaldehyde is combined with the,

cellulose, the product obtainedlaccording to the present invention may contain up to 3 to 4 per cent, or even more, of combined formaldehyde, although we do not limit our invention to the productionofcompounds containing this pro- Portion of formaldehyde. If, for example, the treating solution contains a smaller proportion of formaldehyde, the equilibrium is reached when smaller'proportions of formaldehyde are combined with the cellulose. For instance, if the treating solution contains about 20 per cent of formaldehyde, the reaction equilibrium will be reached when the cellulose contains about 1 per cent oi methylene oxide. The great differences between the products obtained according to the present invention, and that described by Eschalierin the aforesaid British Specification No. 25,647/06, and which is generally term sthenosaged cellulose, are that the products obtained according to the-present invention show no increase in wet strength and possess a high water imbibition, no increasedresistance to creasing and a slightly increased afllnity towards some direct dyes, all ofv which effects are contrary to those possessed by sthenosaged cellulose product's.

The product obtained according to the present invention reacts with nitrogenous compounds such as cyanamide and salts of tertiary bases, for example pyridine and triethanolamine, to give materials having a good afllnity for those dyes normally used for dyeing wool. Its use in this connection isdescribed in the co-flled joint application of John Boult'on andmyself, Serial No. 330,424. I

By heating the formaldehyde-cellulose product oi the invention in the presence of an acid catalyst under dehydrating conditions, the pre- I vlously known sthenosaged product with different properties can be obtained.

The following example illustrates one method I A of carrying out the present invention although the invention is not restricted to this example;

staple fibre marketed under the registered trade-marl: Fibro is immersed in 30 times its .volume of a 40 per -cent solution of formalde,

hyde acidified with sufficient sulphuric acid to form a normal solution, at 80 centigrade for minutes; The fabric is then removed from the solution and washed, first in cold and then in hot running water until all traces of uncombined formaldehyde and sulphuric acid are removed. It is then dried at 105 centigrade for 30 minutes.

What I claim is: l. The production of compounds of! cellulose with formaldehyde by treating cellulose with an aqueous solution of formaldehyde containing a small proportion of an acid catalyst under such conditions of time and temperature that the reaction is allowed to approach its equilibrium,- 'the proportion of the solution of formaldehyde to the cellulose being such that the cellulose is always in a fully swollen state, said solution 'containing 40% formaldehyde, said catalyst being sulphuric acid in decinormal to normal solution, said time being from 10 minutes to 24 hours, and said temperature being from 24 C. to 80 C.

2. The production of compounds of. cellulose rium, the proportion of the solution of formaldehyde to the cellulose being such that the cellulose is always in a fully swollen state, said solution containing 40% formaldehyde, said catalyst being sulphuric acid in decinormal to normal solution, said time being from l0 minutes to 24 hours, and said temperature being from 24 C. to 80 0., removing the uncombined formaldehyde and the acid catalyst from said compound, and thereafter subjecting said compound to dehydra tion.

3. The production of compounds of cellulose with formaldehyde by treating cellulose with an aqueous solution of formaldehyde containing a small proportion of an acid catalyst under such conditions of time and-temperature that the reaction is allowed to. approach its equilibrium, the proportion of the solution of formaldehyde to the cellulose being such that there is present a considerably greater quantity of water than is necessary merely to produce a fully swollen cellulose, and the cellulose is thereby with formaldehyde by treating cellulose with an aqueous solution of formaldehyde containing a small proportion of an acid catalyst under such conditions of time and temperature that thereaction is allowed to approach its equilibalways in a fully swollen state, removing the uncombined formaldehyde and the acid catalyst from said compound, and thereafter subjecting the compound to dehydration, said solution. containing 40% formaldehyde, said catalyst being sulphuric acid in decinormal to normal solution, said time being from 10 minutes to 24 hours, and said temperature being from 24 C. to C.

T. H. MORTON.