US2482578A - Treatment of wool - Google Patents

Description

?e;tentesi Sept. 20, i dg warren spares orifice Stoncham, Mass assignors to Arthur D. Little,

Inc., Cambridge, Mesa, a corporation of Massachusetts No Drawing. Application April 24, 1947,

Serial No. 743,730

15 Claims. (Cl. 8-1216) 1 This invention relates to treating wool to make it more wear resistant, and more particularly to treat wool with a material which chemically reacts with the wool.

In the past cellulose fibers, in particular, have been treated with isocyanates for the purpose of making them water repellent. But treatment of wool fibers and fabrics for extending the wear resistance, and of wool paper mill felts in parcompounds included by this formula are dodecyl v isothiocyanate, octadecyl thiocyanate, octadecyl ketene, heptacosyl ketimine and octacosyl ethyl carbonimide.

The procedure to be chosen for applying the organic compound to the wool depends upon the actual conditions under which treatment may be instituted. At least four methods have been found satisfactory using the compounds employed in this invention. The compound may be applied (1) from solution, (2) from emulsion, (3) from a lick roll, or (4) by spraying. Each of these methods has its particular advantages for the plant equipment that may be. available.

Application from solution requires a solvent recovery system or a solvent disposal system since woolen materials when centrifuged may retain approximately their weight of such solvents as benzene. 0n the other hand an application from solution is uniform and easily accomplished.

The preparation of a stable emulsion from ingredients which do not react over a period of time with the isocyanate used is difllcult to accomplish, although the use of emulsions eliminates any difiiculty incident to the use of solvents.

Application from a lick roll may be made either from a solution or in the undiluted form, is easy and does not present problems of stability and solvent recovery. However, a difficulty with this method is the greater care required to secure even application.

Spraying is a satisfactory method but care must be observed to avoid toxic fumes of the material.

By whatever method the material is put onto the wool, at least 3% by weight is required to cause any substantial increase in wear resistance. Any quantity in excess of 3% may be employedv but amounts in excess of 25% by weight have been found to have no additional value. The preferred quantity from the standpoint of economy and performance is from 4% to 8% by weight. It has been found that when lesser amounts are applied, even in the order of 0.1%, by weight, a type of water repellency is obtained but the wear resistance is not appreciably increased. Surprisingly enough, however, larger quantities do not seriously interfere with the wetting of the treated wool. This fact makes the application of the treatment to paper mill felts feasible. It is well known that paper mill wet end felts wear out rapidly, i. e. in from one to three weeks, and therefore any treatment which would prolong their life would be economically desirable. But such treatment must be one which does not change the character of the felt in its property of passing water freely through it, and its property of "wetting up rapidly and completely. For a reason not known at the present time, application of even relatively large quantities of isocyanates or related chemicals to the felts does not interfere in any material respect with these desirable characteristics. The characteristic of water absorption of woolen clothing, such as woolen socks, is also important and a treatment of such material must be one which does not interfere with the absorption or release of moisture in the vapor form. The treatment with isocyanates does not interfere with such absorption and release. r

The more detailed practice of the invention is illustrated by the following examples. Examples I to V1 show the various methods of treating paper mill felts. In each case the felt treated was cut 6%" wide by about 36" long and weighed 114 grams. For comparison in the wear tests, a similar but untreated felt was run along with the treated felt for the purpose of comparing the relative wearing qualities. Abrasion tests were carried out while the felts were wet with water at 50 0. Such felts are customarily woven with ya'rns running lengthwise, called warps, and yarns running crosswise, called fills. A felt: under the conditions of normal wear, first wears out the fill threads, leaving the warps exposed.

Example I 700 cc. of a 4% octadecyl isocyanate solution in benzene was added to a felt and left for 15 3 minutes. The solution was then further worked into the felt and the excess solution drained oil, leaving about 114 grams of solvent on the felt. The treated felt was placed in an oven and baked at 110 C. for one hour. The pick-up in weight was 3.8 grams over the untreated dried felt at the same moisture content (3% by weight). An

untreated felt (blank) was run simultaneously with the treated felt on a wear-testing machine. The treated felt had considerable wear life remaining at the time the blank had worn so far as to break.

Example I! i The same experiment as in Example I was re- I peated using a 6% solution of octadecyl isocyanate. Substantially the same results as in Example I were securd, except that the treated felt appeared less worn after an equivalent amount of abrasion than that of Example I. In this example about 6% by weight of octadecyl isocyanate on the weight of the felt was added.

Example In Example IV 28 grams of octadecyl isocyanate were sprayed onto a felt and the felt heated in an oven for 1 hour at 110 C. This was equal to about 25% by weight of isocyanate on the weight of felt. The blank wore out and the test was continued until the treated felt had run 2.3 times as long. At the end of that time none of the illls were broken and the felt was still serviceable.

Example V 13 grams of octadecyl isocyanate were put onto a felt by means of a lick roll; 6 grams were distributed on one side, and 7 on the other. The felt was then heated in the oven for 1 hour at 110 C. In a wet wear test the blank was worn out and removed while the treated felt was run 2.17 times as long and showed no evidence of faflure.

Example VI 6 grams of octadecyl isocyanate were put on.

one side of a felt (the side to be exposed to abrasion), as described in Example V, but the felt was heated in the oven for 5 hour at 110 C. After the blank had worn out the treated felt was run up to half again as long a time, at which point it was still in good condition.

Example VII A piece of woolen cloth was treated with 6% decyl isocyanate in benzene solution, heated in an oven at 110 C. for 5 minutes and washed with benzene. A similar, but untreated piece was merely washed with benzene. Comparative tests on a Taber abraser testing machine showed that the treated material wore twice as long as the untreated.

A similar treatment of wool cloth was carried out in which 8% by weight of heptacosylisocyanate (C2'IHssN=C=O) was applied except that 4 the time of heating was 30 minutes. Wear-testing results showed that the treated fabric wore appreciably longer than the untreated material.

Similarly, eicosylisocyanate (C2cH41N=C=O) in a 6% benzene solution gave corresponding good results.

Other members of the isocyanate group beginning with C1oH2iN=C=O and having a greater number of carbon groups in the alkyl chain may be applied in any of the ways described above with equivalent increase in the wear resistance of woolen materials. The carbon chain must, however, be alkyl, as cyclic isocyanates, though they have the proper number of carbon atoms, and appear to give some water repelling action, do not materially aid the wear resistance. Isothiocyanates, being equivalents for isocyanate's, are specifically included as compounds useful for increasing the wear resistance of wool materials. They are applied in the same fashion and include the corresponding alkyl isothiocyanates such as octadecyl isothiocyanate. Isocyanates and isothiocyanates conforming to the requirements of this invention are preferred because of their cost and more general availability.

Other compounds within the foregoing formula R-X=C=Y are the ketenes, e. g. eicosylketene, thioketenes, e. g. octadecyl thioketene, ketenimines, e. g. heptacosylketimine, and carbonimides, e. g. octadecyl carbonamide. Still other compounds conforming to the formula RX=C=Y may be mentioned:

As described above, the chain must be alkyl and its len th must be at least ten carbon atoms. To illustrate this further, the procedure of Example I was followed whereby the felt was treated with a 4% solution of ortho biphenyl isocyanate and baked. No appreciable diflerence was evident between this treated felt and the untreated felt.

The examples given above describe the treatment of finished fabrics. The wool itself may be treated before being processed for use in textile fabrics. In some instances the treatment of the wool itself is to be preferred since the long chain alkyl compound such as an isocyanate may be substituted in whole or, if preferred, in part for the oil used in the customary processing of wool, providing that the oil does not react first with the treating agent. Subsequent washing and scouring steps do not interfere with the increased wearing properties. Instead of treating the raw wool, as above, it may be desirable in some instances to treat yarns before weaving into fabrics. Thus wool may be treated in its raw state, or during processing, or as the finished felted or woven product.

Although no special precautions are necessary to dry the wool to be treated, it is desirable that the wool not be wet with water, alcohol, or other material at the time of treatment which will react with the treating agent used and thus reduce or prevent its reaction with the wool.

The mechanism underlying this invention, while not known with certainty, is believed to involve, in part, the reduction of the fiber to fiber abrasion of the wool. The lubricant in this case appears to be chemically combined because it cannot be removed by boiling with benzene, nor can it be removed by repeated washings with soap and water. This type of lubrication is therefore to be distinguished from that of mineral oil and other lubricants held on the film mechanically or by secondary-order chemical forces. It is thought that a chemical reaction takes place with any reactive hydrogen atoms on the surface of the wool according to the following representative equation:

Thus for wet materials the wear resistance is believed to be enhanced further because the surface of the wool is less sensitive to water, and therefore will swell to a lesser degree. Tests have shown that the more hydrated wool becomes, the shorter becomes its wear life. The treatment of the present invention reduces the possible hydration of the fibers.

The reaction, as is usual with chemical reactions, has a, time-temperature relationship. That is, the reaction may take place at room temperature over a sufficient period of time, but for most practical applications it has been found advantageous to heat the treated wool to at least 50 C. for at least 1 minute. A longer time of heating may be desirable and in no case harms the fabric or treatment, as long as the temperature is not too high. Temperatures not quite up to that which will injure the wool may be employed, 1. e. about 200 C. As disclosed in the examples, however, a temperature of about 110 C. for from 5 minutes to 30 minutes makes certain that the reaction has been completed. Catalysts for aiding the reaction, such as tertiary amines may be employed but they do not ap- I pear to be necessary.

Where only one surface of the material is to be subject to abrasion, only that side need be treated. In the treatment of paper mill felts wherein the isocyanate is sprayed onto the felt, it is permissible to treat only that side which comes in contact with rolls over which it passes in use.

The treatment according to the present invention tends to minimize the difference between wet and dry wear. Presumably one of the reasons for this action, as set forth above, is because the quantity of isocyanate employed reacts with a sufficient number of hydrophilic groups to prevent substantial swelling and gelatinization of the surface of the fibers so that the fibers wear less rapidly.

Having now described our invention, we claim:

1. A method of increasing the wear resistance of wool comprising the steps of distributing on the surface of wool fibers at least 3% by weight of a treating agent having the formula wherein R is an alkyl group having a chain length of at least ten carbon atoms. X is a memher of the group consisting of C and N, and Y is a member of the group consisting of 0, S, and NR where R, is a member of the group consisting of hydrogenand monovalent hydrocarbon radicala'and bringing the treated wool to a temperature of at least C. for at least 1 minute.

2. A method of increasing the wear resistance of woolen fibers, yarns, and fabrics comprising the steps of distributing on the wool at least 3% by weight of a treating agent, said agent having the formula R-.X=C=Y wherein R is an alkyl group having a chain length of at least ten carbon atoms, X is a member of the group consisting of -C and N and Y is a member of the group consisting of O, S, and NR where R is a member of the group consisting of hydrogen and monovalent hydrocarbon radicals, and bringing the treated wool to a temperature of at least 50 C. for at least 1 minute.

3. A method of increasing the wear resistance of woolen fibers, yarns and fabrics comprising the steps of distributing on the wool 3% to 25% by weight of an alkyl isocyanate having a, chain length of at least ten carbon atoms and bringing the treated felt to a temperature of at least 50'' C. for at least 1 minute.

4. A method of increasing the wear resistance of woolen fibers, yarns and fabrics comprising the steps of distributing on the wool 4% to 8% of an alkyl isocyanate having a chain lengthof at least ten carbon atoms, and heating the treated wool to a temperature between 50 C. and 200 C. for at least 1 minute.

5. A method of increasing the wear resistan of a paper mill felt comprising the steps of distributing on the felt 4% to 8% of an alkyl isocyanate having a chain length of at least ten carbon atoms, and heating the treated felt to a temperature between 50 C. and 200 C. for at least 1 minute.

6-. A method of increasing the wear resistance of a paper mill felt comprising the steps of distributing on said felt at least 3% to 25% by weight of an alkyl icocyanate having a chain length of at least ten carbon atoms, and then heating said felt to a temperature of at least 50 C. for at least 1 minute.

7. A method of increasing the wear resistance of a paper mill felt comprising the steps of distributing on said felt from 4% to 8% by weight of an alkyl isocyanate having a chain length of at least ten carbon atoms, and heating said felt to at least 50 C. for at least 1 minute.

8. The method according to claim 6 wherein the isocyanate is octadecyl isocyanate.

9. W001 having bonded chemically to the surface of its fibers at least 3% by weight of an agent having the formula R-X=C=Y wherein R is an alkyl group having a chain length of at least ten carbon atoms, X is a member of the group consisting of C and N and Y is a member of the group consisting of O, S, and NR where R is a member of the group consisting of hydrogen and eans 12. Wool having bonded chemically to its fibers at least 3% by weight of octadecylisocyanate.

13. Woolen fibers, yarns and fabrics having bonded chemically to the surface of the fibers at least 3% by weight of an alkyl isocyanate having a chain length of at least 10 carbon atoms.

14. A paper mill felt having bonded chemically to its fibers at least 3% by weight of an alkyl isocyanate having a chain length of at least 10 carbon atoms.

15. A paper mill felt having bonded chemically to its fibers on the wear surface of said felt from 4% to 8% by weight of octadecyl isocyanate.

ROGER H. DOGGETT. ALFRED R. JOHNSON.

8 REFERENCES CIT The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Datev 2,173,029 Waltmann Sept, 12, 1939 2,284,896 Hanford June 2, 1942 10 2,303,363 Kaase Dec. 1. 1942 2,370,405 Kaase Feb. 27, 1945 FOREIGN PATENTS Number Country Date 461,179 Great Britain 1938 540,613 Great Britain Oct. 23, 1941