US2129737A - Manufacture of artificial materials - Google Patents

Description

Patented Sept. 13, 1938 om'rso STATES PATENT OFFIQE MANUFACTURE or ARTIFICIAL MATERIALS No Drawing. Application January 24, 1935, Serial No. 3,294

2 Claims. (01. 10e -40) This invention relates to the production of filaments, yarns, films, etc. made of or containing an organic derivative of cellulose and particularly to the production of such materials by 5 a process wherein material normally wasted is reclaimed and utilized.

An object of the invention is the economic and expeditious production of artificial filaments, yarns and other articles made of an organic derivative of cellulose. Other objects of the invention will appear from the following detailed description.

In the manufacture of artificial textile material containing organic derivatives of cellulose, there is produced waste consisting of short lengths of yarn, ends of fabric, matted and tangled skeins, tangled pirns, and other forms of material normally considered Waste that is produced in the various operations of spinning, twisting, winding, weaving, etc. Only comparatively clean untreated waste has been previously reclaimed but by employing this invention Waste that contains oils, lubricant compounds, dirt, size, tints, etc. may be reclaimed and returned to the 25 spinning solution of a new batch that is to be spun.

Further, by employing this invention, the organic derivative of cellulose material may be salvaged from waste containing also silk, regenerated cellulose, cotton, wool and other textile materials that have been used with'the organic derivative of cellulose in forming yarns and fabrics.

In accordance with my invention, I treat the waste from the production of textile materials containing organic derivatives of cellulose to recover the same and in a manner that the physical properties, such as solubility, stability, etc. of the same, are not materially affected. Also the organic derivatives of cellulose retain much of their clearness when formed into films and are for all practical purposes of the same suitability as the freshly prepared material.

This invention is applicable to the treatment of waste containing organic derivatives of cellulose to recover the organic derivatives of cellulose unaltered by saponification and without other change in physical or chemical properties. Exarnples of organic derivatives of cellulose are the organic esters of cellulose and the cellulose ethers. Examples of organic esters of cellulose are cellulose acetate, cellulose formate, cellulose propionate and cellulose butyrate, while examples of cellulose ethers are methyl cellulose, ethyl cellulose and benzyl cellulose. Although the invention is applicable to any organic derivatives of cellulose that are not soluble in water, it will be described with particular reference to cellulose acetate.

A preferred method of recovering the cellulose acetate from waste is to place the waste, in order to facilitate handling, in bags or containers, preferably cotton open mesh bags, the mesh of which is small enough to prevent any of the waste from escaping during processing. These bags may be of any suitable size to hold from 1 to 50 or more pounds of waste. For use with the customary machinery employed, mesh bags sulficiently large to hold about twenty pounds of waste may be employed.

One or a number of these mesh bags, containing the required amount of waste may be placed in' any suitable washing machine, for instance, a rotary drum washing machine or hosiery dyeing machine. It is preferable to employ a washing machine that has a rotating drum that is reversible in rotation. The bags may be evenly distributed throughout the drum in order that they may not be overcrowded, and to enable each bag to be subjected to the maximum flow of liquor during the processing.

The method of treatment of waste containing cellulose acetate, as the only fiber material, and which may contain oils, glycols, condensation products of an alcohol with formaldehyde, sizes, tints, dirt and other coating materials or contaminating materials is as follows: The waste in bags is rinsed in water at a temperature of from to C. for from 5 to 20 minutes and then submitted to a treatment in a liquor containing from 0.5 to 1 gram per litre of an alkali carbonate, for instance, sodium carbonate or its equivalent of sodium bicarbonate, and from 5 to 10 grams or more per litre of soapat a temperature of from 70 to C. for 1 hours. After treatment in this bath, the waste may be given one, two or more washings in water maintained at below 70 C. Each washing may continue for from 1 to 20 minutes or more. A final wash in cold water may be given to'the waste. The waste may be dried in any convenient manner.

When the waste contains a large amount of identification tints and/or contains besides the organic derivative of cellulose, fibers or filaments of silk, regenerated cellulose, cotton, wool or other fiber the treatment is the same as above except that from .05 to 0.2 gram per litre of sodium or potassium hydrosulphite may be added to the soap and alkali carbonate bath. The alkali hydrosulphite acts as a reducing agent and both assists in the removal of the coating materials and protects the organic derivatives of eellulose from saponification. The organic derivatives of cellulose may be extracted from the other fibers with a suitable solvent, for instance, cellulose acetate may be extracted with acetone or other suitable solvent.

The organic derivatives of cellulose, cleaned of all foreign material or the extraction liquor containing organic derivatives of cellulose, maybe returned to the system and mixed with freshly prepared material and spun in the normal manner into filaments or yarns or cast into films. It is preferable to return the reclaimed waste material to the system at a point prior to the final filtration of the batch which customarily precedes the spinning and film forming operations.-

By placing the Waste in mesh bags, it is held in a fairly open form allowing the various liquors to penetrate easily and uniformly. The employment of a washing device having a reversible action prevents the waste from packing or felting.

The proportion of soda ash and soap present is preferably just sufiicient to emulsify and remove the coating materials and soil marks without saponifying the organic derivatives of cellulose. The addition of an alkali hydrosulphite to the treating bath aids in removal of the material and protects the organic derivative of cellulose.

The liquor from the heated treating bath may be cooled in a heat exchanger or other device and passed through a trap or otherwise treated to obtain the materials emulsified or formed therein as well as to obtain the emulsifying agents.

The type of soap employed is preferably a substantially neutral vegetable oil soap. However, animal fat, triethanolamine and other soaps may be employed. A part of the soap may be replaced by salts, for instance, trisodium phosphate and the like and/or emulsifying agents, for instance, a sulphonated fatty alcohol or its alkali salt, or the condensation products of taurine and ethionic acid with oleic or similar acid.

The waste textile material as received at the reclaiming process may contain from 1 to 20% or more of its weight of oil, tint, etc. After treatment the tint, dirt, etc. are all removed and the percentage of oil on the waste is reduced to below 1% on the weight of the waste. The cellulose derivative is unaltered and after drying is suitable for re-entry into the spinning system. By reducing the oil, etc. on the waste yarn to below 1% of its weight the degree of corrosion in. the spinning system is greatly reduced and when as high as 40% of the reclaimed waste is blended in the spinning system the oil does not affect the type of thread produced.

For the purpose of quickly redissolving the waste, the drying operation may be stopped while the waste fibers contain as high as 15% moisture but more preferably between 8 and 10% moisture. When moisture is left in the waste fibers, it naturally follows that the concentration of the solvent of the main charge and/or the waste material is so proportioned that the Water content in the charge as it reaches the spinning metier is that desired.

The reclaimed dried waste may be subjected to a grinding and/or pulverizing operation prior to being dissolved.

As an illustration and not as a limitation the following example is given:

Example Cellulose acetate Waste, collected from an entire plant for spinning, winding, Warping and Weaving fabric, containing filaments of cellulose acetate is placed in bags and subjected to water of a temperature of C. for 10 minutes and then submitted to a treatment in a liquor containing0.75 gram per litre of sodium carbonate and 8 grams per litre of soap at a temperature of C. for 1 hours. After treatment in this bath, the waste is given two consecutive washings with water at a temperature of 40 C. for approximately ten minutes in each and then a final Wash in cold water. The waste is then dried to 8% moisture content and then dissolved in acetone and blended back into a filament spinning system just prior to filtration of the dope going to the spinnerets.

It is to be understood that the foregoing detailed description and example are given merely as an illustration and that many alterations may,

be made therein without departing from the spirit of my invention.

The term alkali carbonate as employed hereinafter in the claims is to be construed as including Within its scope the carbonates of the alkali1- metals only.

Having described my invention, what I desire to secure by Letters Patent is:

1. Method of obtaining spinning solutions for the production of filaments, threads and the like from waste filaments, threads and like materials of a water-insoluble organic derivative of cellulose, which comprises removing impurities from said materials by treating the same at a temperature of from 70 to C. with a soap solution containing 5 to 10 grams of soap per liter and also an alkali carbonate in an amount equivalent to 0.5 to 1 gram of sodium carbonate per liter, washing the same in water at below 70 C.,

drying the purified organic derivative of cellulose'obtained, and dissolving the same in a volatile solvent.

2. Method of obtaining spinning solutions for the production of filaments, threads and, the like from Waste filaments, threads and like materials of cellulose acetate, which comprises removing impurities from said materials by treating the same at a temperature of from 70 to 85 C. with a soap solution containing 5 to 10 grams of soap per liter, an alkali carbonate in an amount equivalent to 0.5 to 1 gram of sodium carbonate per liter and also an alkali hydrosulphite, washing the same in water at below 70 C., drying the purified cellulose acetate obtained, and dissolving the same in a volatile solvent.

THOMAS HARVEY HILLIARD.