US2371573A - Process of making ramie yarn - Google Patents

Description

Patented Mar. 13, 1945 PROCESS OF MAKING RAMIE YARN Mark Sabner, London, W.1, England No Drawing. Application June 25, 1940, Serial No.

842,362. In Great Britain June :0, 193a 2 Claims.

This invention. relates to ramie yarn and ar-' ticles, especially hose pipes such as are employed by the fire-fighting services, and other material made of relatively fine count yarn, especially water-impervious material, woven therefrom, and to processes for producing the same.

Such articles as heretofore produced have a' harsh feel, cannot be woven very closely and. have not the strength which should be expectedin view of the stronger character of ramie fibre, as compared with flax, for example. The ramie yarn from which such articles have been woven has been spun wet.

Unlined hose pipes are at present madefrom fiax fibre but there have been many. attempts spread over a large number. of years to produce satisfactory unlined hose pipes from ramie fibre in view of the extra strength thus obtainable. The serious disadvantage of the hose pipes produced, however, has been the fact that the water I has percolated or leaked through the walls there of at a relatively rapid rate. I Attempts have been made to overcome this latter difiiculty by increasing the closeness of the weave but the limitations imposed by the-nature of the ramie yarn hitherto available have always precluded the production of a satisfactory hose pipe. It has now. been fibre was harsh and dry and had to be prepared 3 with softening agentsin order that it mightlend itself easily to the following operations. I have discovered, however, that complete degumming has not heretofore been effected and that in fact it is'a dimcult matter. If, however, sufiicient de-. gumming is effected (i. e. so that not more than 2% of the originally contained gum remains) I have found that the resultingfibre is strong and white and silky in appearance and need not thereafter be subjected as in a prior proposal to treatment to bleach it or to any softening treatment.

found that the primary cause of the troubles experienced both'in hose pipes and mother articles produced from ramie yarn is traceable to themethod of production of the yarn itself which has been spun wet.

Ramie fibre cannot be spun into really satisfactory yarn unless it is first sufliciently de-' gummed. This is because the fibres. cling together due to the gum remaining and thus cannot be properly combed or otherwise treated to cause them to be arranged straight and parallel in which processes they then break.

The treatment of ramie as heretofore carried out has resulted in the gums being only partially removed and the fibres not being completely separated so that the material produced could not be satisfactorily spun in a dry state; further a large I amount of waste was produced in combing. The

fibre has therefore been spun in a wet state with the resulting disadvantage that the fibres harden when'they become dry and are not suitable for the production of many articles. Thus a hose pipe woven from such fibres will not prevent percolation and leakage of water therethroush. Various methods have been suggested for treating ramie to remove the gums and it has been stated that complete degumming has thus been effected despite the fact that the de ummed" As would be expected endeavours have been made to spin ramie fibre, degummed to the extent known heretofore, in a dry state, but the yarn produced has been unsatisfactory even when a damping roller was employed on the dry spinning frame. Thus, the best known process forpreparing ramie yarn consists in treating the ramie to effect degumming to the extent then possible, taking up the "degummed" fibre on a cylinder to form a lap, cutting the lap into sheets about 10" long, placing the sheets in the "books" of the dressing frame, and then combing and subsequently,

spimiing the fibres. Thispro'cess inevitably leads to the wastage of many long fibres which are cut into short lengths and cannot in any case produce yarn having the fine count and the soft silky feel, as described herein, which I consider necessary for the production of fire hose or other water-impervious material. Itv has now been found that bytreating the ramie to remove sufficient of the gums i. e. so that not more than 2%, or 'even less, of the originally contained gum remains as for example by the process described 'inthe specifications of applications Nos. 342,363 and 342,364, yarns may be produced in relatively fine counts and the fibres remain soft and strong. They may also be combed or otherwise treated to cause them to be arranged straight and parallel or substantially so' and spun in a. dry condition so avoiding the disadvantages of ramie fibres produced as heretofore. This process renders unnecessary the step of taking up on to a cylinder to form a lap and avoids the wastage arising from cutting the lap into narrow sheets for further treatment. The spun yarn may be woven more closely thanthe ramie yarns so far available and the articles produced have the desirable soft feel" and effect. An important advantage is that, for instance hose pipes or cloth for making tents may be wovenfrom the yarn with a much closer weave than has hitherto been possible and in this way such articles may be produced which are better than those at present made from fiax fibre. According to the present invention, ramie yarn to be employed in the production of woven articles, e. g. hose pipes, is produced by a method which consists intreating ramie fibres to eflfect of a solution of a caustic alkali of a concentration of not more than 0.5%, and preferably 0.25%, by weight of caustic alkali, the boiling is continued for not more than half an hour, the treatment medium is drained off, the fibres are squeezed by direct pressure (in contradistinction to centrifugal pressure) to remove the treatment medium and are washed with water which is removed and then neutralized with a weak acid solution e. g. 0.25% hydrochloric acid,.and rinsed again, the whole process being repeated at least six times.

The fibres should be separate from each other, i. e. not adhering together and long fibres of at least three inches in length give a particularly satisfactory result.

A further feature of the invention consists in a hose pipe woven from ramie fibre in which the V fibre has been treated to cause it to absorb a relatively small proportion ofa water-insoluble substance or substances that will prevent deterioration of the fibre. The fibre may be treated to pro- .duce the desired result at any desired stage, for example while still in the form of "filasse (i. e. unspun cleaned fibres), while in the form of yarn or after the pipe has been woven. Suitable substances are various types of wax, with or without appropriate plasticislng agents, which are dissolvedin a solvent, such as an oil or turpentine, that is later removed and recovered. A certain degree of absorbency is required in the ramie fibre for the proper functioning of the hose pipe produced therefrom and for this reason rubber! latex cannot be employed as the treating substance.

It is of course known to line canvas hose pipes with rubber but the hose pipes according to the present invention aredistinct from' such lined pipes.

Alternatively the treatment maybe with an emulsion in which the disperse phase is a solution of parafiin wax, for example in turpentine oil and the continuous phase an aqueous solution of .a soap containing a very small percentage of alkali, for example, saponified olive oil. If desired,

a small proportion of gold size may be added to otherwise treated to cause them to be arranged straight and parallel and are then ready for spinning in a dry state.

If the fibre is not thoroughly degummed the yarn is inclined to be wirey, l. e. to have fibre ends projecting from it, which may make it difiicult to weave. .The friction produced by the projecting ends may cause a tendency for the yarn to-fray thereby producing an unsatisfactory result. If the fibre is properly degummed a smoother yarn is produced from which better results are obtained.

It may be noted that the figure of 2% of the natural content of gum resins, to which, at least, the gums contained in the ramie fibre by my process are reduced, is not a critical figure in the sense that products whose gum content are respectivelyfractionally above and fractionally below 2% differ radically from each other in their properties. There is a more or less progressive improvement in these properties from somewhat above 2% to considerably less than that figure, in respect of the properties which I desire, softness, natural whiteness, ability to comb the fibre without substantial loss into condition for dryspinning, etc. The figure of 2% is, however, in accordance with my invention, considered as being substantially the upper limit of gum content with which the advantages of my invention may be obtained substantially in commercial practice. In myexperience and knowledge of ramie fibre or yarn heretofore produced the gum content has always been 3% and upwards of the natural content of the material, often I should say, 5% and upwards, and it'is easily demonstrablethat ramie containing such proportions of gum is markedly different, in the properties referred to above, from ramie containing 2% or less, so that the former cannot be used to practise the invention herein described. The figure of 2% is therefore considered critical in the sense described.

It may be stated that ramie ribbons (the raw material) normally contain about 55% by weight of gums. Therefore about 2% of the originally contained gums is also about 2% of the fibre treated by the present process.

What I claim is:

1. A process for the production of ramie yarn for use in preparing woven articles, which consists in repeatedly subjecting ramie fibres to alkali boiling, pressing, and washing to effect sufficient degumming so that not more than 2% of the originally contained gum remains and the treated fibres have a soft feel and a sufiiciently white colour to render subsequent bleaching unnecessary, then combing the treated fibres to cause them to be arranged substantially straight and parallel and then spinning them in the dry state.

2. A process for the production of ramie yarn for use in-preparing woven articles, which consists in repeatedly subjecting ramie fibres to alkali boiling, pressing. and washing to effect sufficient degumming so that not more than 2% of the originally contained'gum remains and the treated fibres have a soft feel and a sufficiently white colour to render subsequent bleaching unnecessary, impregnating the fibres with a waxy material, combing them to cause them to be arranged substantially straight and parallel, and thenspinning them in the drystate.

. MARK SABNER.