US2687351A

US2687351A - Ramie fiber separation

Info

Publication number: US2687351A
Application number: US252790A
Authority: US
Inventors: Rinse Jacobus
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-10-23
Filing date: 1951-10-23
Publication date: 1954-08-24
Anticipated expiration: 1971-08-24

Description

Patented Aug. 24, 1954 OFFICE RAMIE FIBER. SEPARATION Jacobus Rinse, Bernardsville, N. J.

No Drawing. Application October 23, 1951, Serial No. 252,790

This invention relates to a process for the separation of the fibers from raw ramie fibrous masses without substantially impairing flexibility, strength and other desirable characteristics of the individual fibers, thereby providing the fibers in a condition suitable for the production of cloth and other articles of commerce.

Heretofore attempts have been made to separate the individual ramie fibers from raw ramie fibrous massees wherein the cellulosic fibers are bound together with natural binding substances, such as gums, lignins, and the like, by subjecting the fibrous masses to the action of relatively strong alkalies, such as sodium hydroxide, sodium silicates, trisodium phosphate, or the like. In such prior treatments, however, in order to 3 Claims. (Cl. 92 l) from each other, and then, most desirably further treating the fibers with a dilute acid solution to effect more complete separation of the fibers. The correlation of the conditions employed during the alkali-zinc oxide treatment of ramie may be and generally is different from that required in the treatment of agave and Manila hemp fibrous masses. The treatment conditions of the ramie usually must be weaker.

In my preferred mode of operation the raw fibers (fibrous masses) are treated in a hot alkali make such chemicals suficiently active to remove I the natural binding substances it has been necessary to use such high temperatures or concentrations of alkalies, or both, that the tensile strength of the fibers has been considerably reduced and an appreciable loss of cellulosic materials has occurred. 1

In copending application, Serial Number 46,372, filed on August 26, 1948, by Hendricusstephanus and myself, now U. S. Patent No. 2,591,315, we have described a process for separating the fibers from raw agave or Manila hemp fibrous masses Without substantially impairing the quality of the recovered fibers. Broadly considered, the process involves contacting the fibrous masses with an aqueous alkali metal hydroxide solution of about 3-15% concentration (calculated as sodium hydroxide) containing dissolved therein at least 0.5% (calculated as oxide) of either aluminum or zinc oxides or hydroxides, or both, until the binding substances are substantially dissolved, removing the solution containing the binding substances dissolved therein from the freed fibers, then washing with water at ordinary, temperatures to remove the residual solution, and finally drying. Now I have found that the fibers of raw ramie can be recovered without substantially impairing the strength of the recovered cellulosio fibers'by subjecting the raw ramie to a hot aqueous solution of an alkali metal hydroxide of about 23-15% concentration (calculated as sodium hydroxide) containin dissolved therein at least 0.5% of zinc oxide or hydroxide whereby binding substances are gelatinized but not removed,

next subjecting the fibers, which are still bound together, to the action of hot-water at a temperature of at least 70 (3., whereby the fibers are substantially freed of binder and separated time of treatment are metal hydroxide solution at concentrations below 15%, generally at 3l.0% strength, at elevated temperatures of the order of -100 C., preferably Bil-100 C.,' for a period of time of from to 2 hours. Superatmospheric pressures and temperatures over 100 C. can be used provided the strength of the alkaline solution and the regulated such that the fibers are not weakened to any substantial degree, but ordinarily such conditions are not necessary or desirable.

The quantity of zinc oxide or hydroxide in the aqueous alkali solution should be at least 0.5% (calculated as oxide). The maximum quantity utilizable is usuallydetermined by the solubility of the zinc ion in the alkali metal hydroxide solution employed. From 1 to 6% of zinc oxide or hydroxide, (calculated as oxide) is preferably employed. f

The'concentration of the ingredients in the aqueous alkali metal hydroxide solution, the ternperatureand the time employed in my process are correlated in such manner that the binding or encrustating substances between the fibers, such as pectins, lignins, gums, or other natural binding substances, are softened and swollen and ,the gums transformed into a gel while at the same time leaving the individual fibers substantially unattacked. The binding substances, therefore, are not appreciably removed by this treatment and the fibers are'not separated thereby. Solutions of alkalifmetal hydroxide other than sodium hydroxide maybe used to like effect.

After ,thetreatment of the fibrous masses with the alkaline solutions of alkali metal hydroxides and oxy-compoundsof'zinc, the resulting fibers are squeezed to remove excess solution and then continually (intermittently or continuously) subjected to the action of hot Water at a temperature of at least '70 ;C., and preferably at temperatures of -100 ;C L,; until the gelatinizednatural bind.- ing substances'a-re substantially removed from between the cellulosic:fibers.' The-fibers may require repeated or prolonged treatment with fresh hot water, the treatment being continued until the used water is no longer discolored. Clear water indicates that most, if not all, of the gelatinized binding substances have been dissolved out or removed.

After the treatment with hot water, a small amount of the binding substance may remain, but the adhesion remaining between some of the fibers is greatly weakened. Any residual adhesion among the fibers can be destroyed by subjecting the fibers to the action of a dilute organic or inorganic acid, such as hydrochloric acid or acetic acid. The concentration of the dilute acid is adjusted such that the strength of the acid is not suificient to injure the cellulosic fibers and such that the time of treatment is not uneconomically long. The subjecion of the fibers to the action of a to 1% hydrochloric acid solution or a l-5 or lesser concentrated solution of acetic acid or gluconic acid at from room temperature to about 60 C. for a period of from 5 to 60 minutes usually enough to free the fibers and leave them in a condition suitable for the formation of fabrics and other articles of commerce.

After the acid treatment the fibers are washed and dried. Strong, flexible cellulosic fibers are thereby obtained.

After completion of the process, the fibers may be subjected to bleaching, softening, hackling, or other treatments customarily applied to fibers before they are spun into yarns or woven into fabrics.

The following examples further illustrate the invention wherein the amounts of fibers and reagents employed are expressed in parts by weight.

One thousand grams of crude Florida ramie is heated for a period of 90 minutes at 95 C. with an aqueous solution containing 6% sodium hydroxide and 1% zinc oxide. After removal of the solution, the fibrous mass in which the fibers are still bound together is treated several times with water of 80 C. until the used water is no longer colored, at which time the fibers will have been substantially separated. Thereafter the massis transferred to a water bath containing [2% of H01 maintained at approximately room temperatures or from -30 C. The ramie remains in this bath until the residual adhesion among the fibers is sufiiciently weakened such that the fibers are well adapted to further conventional processing. fter the fibers are subjected to the treatment in the .acid bath, they are washed with water and then dried.

Example 2 One thousand grams of crude or raw Japanese ramie is heated for a period of 60 minutes at 98 C. with an aqueous solution containing 8% of sodium hydroxide and 1.3% of zinc oxide. The solution is then removed from the fibrous mass. After several treatments with water of 80 C., the water is no longer colored and the gelatinized gums formed in the alkali treatment and other natural binding substances are substantially removed. The fibers, substantially freed of the binding substances are then transferred to an aqueous bath containing 1% acetic acid maintained at about 20-30 C. After treatment in the acetic acid bath and several washings with fresh water, the cellulosic fibers are sufiiciently separated or loosened to permit their further processing and use in accordance with known techniques.

Example 3 One thousand grams of raw Florida ramie is heated for a period of 1 hour at C. in an aqueous soution containing 11.6% of sodium hydroxide and 4.7% of zinc oxide. A white precipitate of zinc hydroxide forms and at the same time the natural gums binding the fibers together are gelatinized and rendered soluble. The treated fibers are then treated several times with water at 90 C. until the water is no longer colored. The fibers with substantially all of the natural binding substances removed are then transferred to an aqueous bath containing 1% gluconic acid vmaintained at 2030 C. and are retained in this bath until the fibers are sufficiently free to render them suitable for further conventional processing. Upon removal from the gluconic acid bath the fibers are repeatedly washed with pure water and upon drying the fibers are ready for the processing.

The process of the present invention has the outstanding advantage that the treatment conditions may readily be so chosen that the undesired binding components of the raw fibrous masses, such as pectin, lignin, gums, and the like, can be dissolved out without the cellulosic fibers themselves being chemically attacked to any substantial degree. As a result, substances cross-linking or binding the fibers together are removed and the fibers retain substantially their original length and tensile strength. The process also has the additional advantage that the loss of cellulosic material is ordinarily very small. he process has the additional advantage that it is not necessary to pro-bleach the fibers, hence the costs and the detrimental effects of such preibleaching operations are avoided.

The practice of this invention has been exemplified herein by various detailed conditions and examples which are included for illustrative purposes. It wi l be understood, therefore, that these conditions may be varied somewhat without departing from the spirit or the scope of the invention defined by the appended claims.

What is claimed is:

l. A process for the production of flexible, cellulosic fibers from raw ramie fibrous masses, the individual fibers of which are bound together with lignin and other natural binding substances, which comprises contacting the said fibrous masses at a temperature between about 80-100 C. with an aqueous alkali metal hydroxide solution of between about 340% concentration (calculated as sodium hydroxide) containing dissolved therein from 145% (calcu-- lated as oxide) of a compound selected from zinc oxide and zinc hydroxide for a period of onehalf to two hours until natural binding substances are gelatiniaed while leaving the cellu- -losic fibers substantially free from attack, subjecting the fibers continually to the action of hot water at temperatures of from IO- C. until the used water is no longer substantially discolored by matter removed from the fibers, and subjecting the fibers to a treatment in a dilute acid solution to free remaining adhering fibers, whereby strong, flexible, cellulosic fibers are obtained.

2. A process for the production of flexible, cellulosic fibers from raw ramie fibrous masses, the individual fibers of which are bound together with lignin and other natural binding substances, which comprises contacting the said fibrous masses at a temperature between about 80-100" C. with an aqueous sodium hydroxide solution of between about 340% concentration containing dissolved therein from 1-6% (calculated as oxide) of a compound selected from zinc oxide and zinc hydroxide for a period of one-half to two hours until natural binding substances are gelatinized while leaving the cellulosic fibers substantially free from attack, subjecting the fibers continuously to the action of hot water at temperatures of from 80-100 C. until the used water is no longer substantially discolored by matter removed from the fibers, subjecting the fibers to a treatment in a dilute acid solution to free remaining adhering fibers, rinsing with water and drying the fibers, whereby strong, fiexible, cellulosic fibers are obtained.

3. A process for the production of flexible, cellulosic fibers from raw ramie fibrous masses, the individual fibers of which are bound together with lignin and other natural binding substances, which comprises contacting the said fibrous masses at temperatures between 80-100 C. with an aqueous sodium hydroxide solution of between 23-10% concentration (calculated as sodium hydroxide) containing dissolved therein at least 0.5% (calculated as oxide) of a compound selected from zinc oxide and zinc hydroxide for a period of to 2 hours whereupon the "binding substances will be transformed into a gelatinized mass which can be removed by the action of hot water while leaving the cellulosic fibers substantilaly free from attack, continually subjecting the fibrous masses to the action of hot water at a temperature of from '70-100 C. until the binding substances are substantially removed, subjecting the fibers obtained to the action of a dilute acid solution at substantially room temperatures to free remaining adhering fibers, whereby strong, flexible, cellulosic fibers are obtained.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 55,386 Dixon June 26, 1866 1,630,365 Weber May 31, 1927 2,527,141 Mantell Oct. 24, 1950 2,530,244 Jensen Nov. 14, 1950 2,536,334 Weiss Jan. 2, 1951 2,591,315 Stephanus et a1 Apr. 1, 1952 FOREIGN PATENTS Number Country Date 20,314 Great Britain Dec. 17, 1890 of 1889 324,520 Germany Aug. 28, 1920

Claims

1. A PROCESS FOR THE PRODUCTION OF FLEXIBLE, CELLULOSIC FIBERS FROM RAW RAMIE FIBROUS MASSES, THE INDIVIDUAL FIBERS OF WHICH ARE BOUND TOGETHER WITH LIGNIN AND OTHER NATURAL BINDING SUBSTANCES, WHICH COMPRISES CONTACTING THE SAID FIBROUS MASSES AT A TEMPERATURE BETWEEN ABOUT 80-100* C. WITH AN AQUEOUS ALKALI METAL HYDROXIDE SOLUTION OF BETWEEN ABOUT 3-10% CONCENTRATION (CALCULATED AS SODIUM HYDROXIDE) CONTAINING DISSOLVED THEREIN FROM 1-6% (CALCULATED AS OXIDE) OF A COMPOUND SELECTED FROM ZINC OXIDE AND ZINC HYDROXIDE FOR A PERIOD OF ONEHALF TO TWO HOURS UNTIL NATURAL BINDING SUBSTANCES ARE GELATINIZED WHILE LEAVING THE CELLULOSIC FIBERS SUBSTANTIALLY FREE FROM ATTACK, SUBJECTING THE FIBERS CONTINUALLY TO THE ACTION OF HOT WATER AT TEMPERATURE OF FROM 70-100* C. UNTIL THE USED WATER IS NO LONGER SUBSTANTIALLY DISCOLORED BY MATTER REMOVED FROM THE FIBERS, AND SUBJECTING THE FIBERS TO A TREATMENT IN A DILUTE ACID SOLUTION TO FREE REMAINING ADHERING FIBERS, WHEREBY STRONG, FLEXIBLE, CELLULOSIC FIBERS ARE OBTAINED.