US2519842A - Treatment of wool and other animal fibers - Google Patents

Description

Patented Aug. 22, 3950' TREATMENT OF WOOL AND OTHER ANIMAL FIBERS Leendert Maaskant, Arnhem, Netherlands, as-

signor to American 'Enka Corporation, Enka, N. 0., a corporation of Delaware No Drawing.

Application Februa y 18, 1948, Se-

rial No. 9,333. In the Netherlands June 28,

11 Claims.

The present invention relates to the treatment of animal fibers and products formed therefrom. More particularly, the invention is directed to a method of improving the physical and chemical properties of wool and other animal fibers, yarns, fabrics, knitted materials andfinished articles.

One of the most important of these materials is wool because of its warmth-insulating property its comfort of wearing and the ease with which it can be spun into fibers and fulled dur-- ing processing for certain purposes. Wool also has an appreciable resistance to acids which renders it suitable for certain types of clothing used in places where protection against acid is necessary. This acid-resisting property of wool renders it suitable for filter cloth and filter bags for the filtration of acid solutions, although its durability in this respect is limited and the treatment comprehended by the present invention makes it possible to use wool more intensively for certain purposes.

On the other hand, the strength properties and some chemical properties of wool are not so favorable. One of the most important failings of wool is its sensitiveness to alkalies so that the utmost caution must be exercised to prevent it from coming into contact therewith. Even in a normal washing operation using a weakly alkaline soap solution at moderate temperature, this disadvantage is noticeable, and a boiling operation with dilute soap or soda solutions is entirely impracticable. In general, wool and other animal fibers are also sensitive to bleaching wherein it or they are not sufficiently resistant to chlorine treatment (hypochlorite). Another disagreeable property of wool is that it is subject to destructure which is peculiar to wool and which cannot be said of artificial textile products such as viscose rayon, casein or nylon threads which are spun from a homogeneous viscous solution.

In my co-pending application Serial No. 760,- 936, filed July 14, 1947, there is disclosed and claimed a process and product involving the aftertreatment of synthetic protein products such as casein with precondensation products of an aldehyde and resorcinol or a substituted resorcinal. However, it could not'be determined that such treatment would be applicable to animal fibers such as wool, because wool is characterized by a special fibrous keratin structure which is based on a tridimensional network of --S-S- bridges (sulphur bridges) whereas casein may be considered a phosphor proteid of the globulin type, wherein there exists no real fiber structure.

Therefore, the dissolving properties of the two proteid substances difier in principle, in that, whereas wool is hydrolyzable under certain circumstances, particularly with alkalies, it is not normally easily soluble. On the other hand casein dissolves in a dilute ammonia solution. However, the behaviour of a technical thoroughly hardened commercial casein is again quite different. Wool, for example, hydrolyzes completely under proper conditions and may be dissolved when it is treated for one houiwith a 4% caustic soda solution at 50 C. Under similar conditions, the normal commercial casein thread dissolves only to a very limited extent, i. e., often less than 1%.

Various attempts have been made to improve the properties of wool and other animal fibers or hair by a suitable aftertreatment. When certain precautions are observed, it was determined that the creasing and water-absorbing power could be decreased by a treatment with precondensation products from phenol or urea and formaldehyde or their components, followed by a hardening on the fiber. It was determined, however, that local deposits of the resin were often formed on the surface of the fiber which resulted in their sticking together. When this occurred, it gave rise to a decrease in resistance to abrasion and to creasing, and in addition the softness of the fiber decreased. The treatment with these precondensation products only improved the chemical properties of the wool to a very small extent. The urea-formaldehyde-condensation-products which were deposited on the wool, or were condensed on it, were not resistant to acids or even to boiling water, but due to hydrolysis were dissolved.

Neither the treatment with urea-formaldehyde-condensation-products nor with phenolformaldehyde condensation products protects wool and other animal fibers sufficiently against alkalies. The experiments showed that the low degree of protection afforded by these substances was due to the fact that the condensation products only enveloped the fiber and acted much the same as an armor or film-like coat. It is also possible that these condensation products penetrate under the scales of the wool and into the crevices, but it is believed that the wool or hair is not changed and does not combine chemically with the condensation products.

It is therefore an object of the present invention to provide a process for the aftertreatment of wool and other animal fibers, intermediate products and finished products manufactured from them, and also fleeces, whereby the chemical and physical properties of the materials are substantially improved.

It is a further object of this invention to treat wool fibers and the like with precondensation products that actually react chemically with the fiber itself so that the fiber is at least partially modified chemically, i. e., its sensitive or reactive groups are blocked or combined with the precondensation products.

Another object of this invention is the production of an improved animal fiber and articles formed therefrom which has been treated with a precondensation product of an aldehyde with resorcinol or with substituted resorcinols.

According to the invention an aqueous acid precondensation solution is prepared by dissolving resorcinol in an approximately 35% formaldehyde solution in a ratio of one gram-molecule of resorcinol to at least 6 gram-molecules of formaldehyde. By heating this solution at about 60 C. for about one-half hour, it is brought to the proper stage of precondensation. The pH of this concentrated resorcinol formaldehyde solution should be adjusted to a value between 4.5

and 2.8. Next, the solution is diluted with water until the concentration of the originally dissolved resorcinol is 0.5% to 1.0%. The pH value of this dilute solution should be adjusted to a value between 45 and 5.5, at which time it is in condition for the treatment of wool.

At room temperature or at a slightly higher temperature (40 C.) the precondensation solution is very stable, i. e., the condensation process continues very slowly.

Next, the wool is treated with the precondensation solution by immersion, preferably at an increased temperature at about 40-45 C. It was determined that the precondensation product was substantively absorbed by the fibers. After centrifuging and drying the wool product is then heated above 100 0., preferably at about 105 C., for about one-half an hour, whereby the product is hardened.

It is to be noted from the above description of the preparation of the precondensates that the precondensation solution must be acid and that a large excess of formaldehyde must be used, and although this preparation can be varied within wide limits, the pH value must be maintained within the limits given above, or otherwise the condensation reaction may continue to an undesired stage both in the concentrated solution and after dilution. If the pH value of the solution lies outside of the preferred range, this value can be corrected by the addition of weak alkalies or acids. If an acid is required, lactic acid is advisable.

It is important that these precondensates are substantively absorbed, because then dilute solutions can be employed which reduce losses, and also the sticking together of the fibers is minimized, whereby the wool products treated with the precondensates have an increased pliability. In view of this substantivity and reactivity of the resorcinol-formaldehyde precondensates with respect to wool, the effects are entirely different from those which are obtained by means of urea-, phenolor melamine precondensation products. These last three products effect only very little improvement in the chemical property of wool.

In general, it was determined that effective results were obtained by depositing about 5% of the precondensation product on the wool. The absorption is dependent on various factors such as the temperature at which the treatment takes place, the concentration of the solution, the liquid ratio and the time of immersion. Other things being equal, the quantity absorbed increases within certain limits with the temperature applied during the treatment, the concentration of the solution and the liquid ratio. Thus, in practice, the quantity to be absorbed can be predetermined and regulated by the proper selection of working conditions. In any case, it is advisable to use an excess of the precondensation product.

These precondensation products can be used with beneficial results on wool fiock, immediately after washing the wool and also on yarns, fabrics, knitted materials and even on finished articles such as wool cloth out to size, filter cloth, woolen filter bags, woolen clothing, including protective clothing, woolen carpets, and also on other animal hairs such as horse hair, cow hair, hogs hair, felt from wool or hairs, and even fieeces. For convenience and brevity, these materials are referred to hereinafter as keratinaceous animal fibers, this term being employed to refer to such fibers whether present in the form of fibers as such or as finished articles including such fibers.

The following examples serve to illustrate various applications of the precondensates to wool fibers and the like and products formed there from.

EXAMPLE 1 500 gms. resorcinol were dissolved in 3 liters of a, 36% formaldehyde solution. This mixture was heated for 30 minutes at 60 C. (pH=3.4). After cooling, 4'] liters of water were added. The pH of the solution was then 4.8. Thereupon 2 kilograms of freshly washed wool fibers were thoroughly rinsed, centrifuged and immersed in this 50 liter solution at room temperature. While stirring at intervals the wool was left in this solution for 30 minutes. It was then centrifuged, dried at C. and finally heated at C.

EXAMPLE 2 Unfinished woolen cloth was treated for A or an hour at 40 C. in a vat containing a dilute solution of the precondensation products prepared in accordance with'Example l. The cloth was then withdrawn, hydroextracted, and dried in a drying room at 70 C. and finally hardened for 30 minutes at 105 C.

Examples 1 and 2 were conducted under identically the same conditions with the exception that a substituted resorcinol was used instead of resorcinol, namely, 1-3-dihydroxy-6-chloro-benzene was used. In this case the quantities were modified in accordance with the difference in molecular weight between resorcinol and its substitution product.

3, it was determined that after the same acid treatment, the strength had decreased to a far lesser extent. The comparative strengths were determined on strips of a width of 30 mm.

EXAMPLE 3 A dilute precondensation solution was prepared fffgg im gz by dissolving 5 parts of resorcinol in 40 parts of a 36% formaldehyde solution. The solution was dry Wet dry wet adjusted to a pH of 3.4 and heated for 30 minutes at 60 0. and finally diluted with cold water. kg. km W M This precondensation solution contained 10 untreated 4.3 3.5 5.0 2.2 grams of resorcinol and 80 grams of forinaldetreated hyde solution per liter calculated on the original chemicals. Finished woolen articles, 1. e., cloth- From the above it can be Seen that the strength ing and filter bags were introduced into a rotatof the trefited fabric in both the dry and Wet ing drum, together with 2 times as much of the state has increased greatly over that of the undilute precondensation solution. While rotating treajted fabricthe drum slowly, the articles were treated at 40 3 F11$r$ags g fiz fi 5 3 1 3 y w c were use or re. ion 0 o aci fi if fi flg gfgi {i s mfi g fij ggs :0 spinning baths, showed that they had about centrifuged and dried at and hardened by twice the life of the untreated ones. Moreover, exposing them to a hot air current of 105 C. for the Woolen protectiv? clothing worn by Operaminutes. tors in rayon factorles was substantially more EXAMPLE 4 durable than untreated woolen protective clothe" in worn under the same conditions. A preconden-sation solution was prepared by 0 g dissolving 5 parts of resorcinol in 40 parts of a Hzgher resistance to Qmomw treatment 33% formaldehyde solution. The solution was (hypochlonte) djusted to a p of heated at f The treated and untreated material was sub- 30 minutes and diluted with water. This solution 30 jected t a very intensive chlorine treatment contain d 5 em 0 f r s l and 40 grams of (bleaching operation). After this treatment formaldehyde solutlon per liter calculated on the hi was somewhat exaggerated the untreated original chemicals. A fulled felt was introduced t i l Showed a number of large holes While to a p e f 25 s as m1 10h 0f the treated material still had a good appearance. pr ec9ndensatlon Solutlon- Whlle qlrculetmg 35 In order to further illustrate the effects of this stirrin slowly, the felt was treated in thlsvat at intensive treatment, the strengths f strips of 35 o. for 6 hours. The felt was then centr fug the treated and. untreated material were measagain exposed to the impregnating solution for a, d are as follows; 30 minutes, centrifuged a second time and dried in the air, and after this, completely dried at 70 I C. Finally, the felt was hardened in a hot air t l ii w l tttif current at 105 C.

In the above examples, and with reference dry wet dry wet more particularly to Example 3, the articles were tested and found to have a number of improved 4:, m ft m m lg. kg. kg. 0- phlg i d em al lfiloperties. tA OIfIID entities;fitiii tifive fiiis t 0' ese proper ies o e proper ies 0 an uns -7 1.3 90 treated article will be given in detail below.

a.,1ncrease in the strength of the fabric Decrease m shrinkage For the purpose of this experiment the fi i i i standmid strengths were determined on strips of 50 mm. as g proce ure W Ou any spam mecham' in width. cal treatment. Pieces of thin wool cloth were used for this examination.

Direction of Direction oi the warp a the weft Warp Weft dry wet dry Wet V UNTREATED k #9- aai i stiilti f untreated 68.6 56-6 45-9 7- 6O 5washings... treated 84.1 63-0 5 -8 8- l0 washings..;

The above shows that after treatment, the \r f g l sg gg on cloth) strengths of the strips have increased both in y the direction of the warp and of the weft. us shrinkage 8MP b. Increased resistance to acid iltiifiifigi 13 $1.

h An untreated woolen fabric was treated with 10 was mgs 3 3 3 0 N/l sulphuric acid at 95 C. for 4 hours. A com siderable part of the keratin protein was dis- Increase of the abrasion resistance solved while the structure of the fabric had dis- Abrasion measurements were carried out with appeared for the greater part. The strength of the Schopper abrasion machine. The load durthe fiber was only a small fraction of that before ing the measurement was 2 kg. and the number the treatment. However, when the wool maof rotations amounted to 2000. All the samples terial had been treated as described in Example were tested under these conditions.

The loss in thickness determined by means of the Schopper thickness tester at the places, which had not been exposed to abrasion and which had been exposed to abrasion was practically equal in both cases (about 2.5%). The strip strength was determined of the exposed parts in the direction of the warp threads. The width of these strips was 2%; cm. and the length about 4 cm. The strip strength found at the places exposed to abrasion of the untreated and treated wool material were as follows:

strip strength (average of 4 determinations) of untreated material 1.3 kg. Strip strength (average of 4 determinations) of treated material 4.5 kg.

These figures show, that the resistance to abrasion has increased after the treatment (4.5% resin on cloth).

1. Increase of the resistance to moths Experiments showed that after the treatment the wool material was appreciably more resistant to moths. This investigation was conducted by the Vezelinstituut T. N. O. at Delft, Holland. The result of the experiment, which comprised generally the subjection of treated and untreated woolen fabric to moths which had been cultivated in the Vezelinstituut, was as follows: Both the untreated and the treated fabrics have been attacked. There is, however, a clear difference visible in the degree of attack. The attack of the sample marked in red is less strong. If the attack of the untreated fabric is assumed to be 100, at a visual estimation the attack of the sample marked in blue is 75 and that of the fabric marked in red 20. This is quoted from the Report of the Vezelinstituut, wherein the sample marked in blue refers to the material treated with formaldehyde only, whereas the sample marked in red has been treated with the precondensation products of resorcinol and formaldehyde.

Further samples were submitted to the Vezelinstituut in which the untreated ones and the ones treated with formaldehyde were uncoloured, and the ones treated with precondensation products of resorcinol and formaldehyde were coloured. Quoting from the findings by the Vezelinstituut, the Report reads as follows: Both the coloured and the uncoloured pieces of fabric had been attacked by moth-larvae. The coloured sample has been shorn only superficially; the uncoloured samples have been damaged moderately, while holes are present in them."

The above experiment clearly shows that the material treated with resorcinol formaldehyde precondensation products has a better resistance to moths.

9. Higher resistance to alkalies A treated and untreated piece of woolen cloth were introduced into a N/l NaOH solution at room temperature for about minutes. At the end of this time the percentage of dissolved wool was determinedand it was found that of the treated material had dissolved, whereas of the untreated material had dissolved.

Referring now in general to the hardening of the precondensation on the fibers, it is to be 'pointed out that this can be effected at a temperature slightly above C. As mentioned in the examples, the operations can be conducted successfully at C. However, it was determined that it was not desirable to exceed 140 C.

during the hardening operation due to the sensitiveness of the wool to higher temperatures. As a matter of fact, it was found that it was not necessary to raise the temperature above C. when operating in accordance with the present invention.

In addition to the improved properties specifically mentioned and determined as pointed out above, the fibers show practically no tendency to stick together, and as a result of which the products exhibit a remarkable softness.

What is claimed is:

1. A process of improving the physical and chemical properties of keratinaceous animal fibers, which comprises the steps of treating the fibers with a weakly acidic solution containing precondensation products of (a) formaldehyde and (b) a compound of the class consisting of resorcinol and chloro-substituted resorcinols in the preparation of which at least six mols of (a) per mol of (b) are employed, centrifuging the thus treated fibers and drying the same by heating.

2. A process according to claim 1 wherein the precondensation products are of formaldehyde and resorcinol.

3. A process according to claim 1 wherein the precondensationproducts are of formaldehyde and 1.3 dihydroxy 6. chloro-benzene.

4. In a process of improving the physical and chemical properties of keratinaceous animal fibers, the steps which comprise dissolving (b) a compound of the class consisting of resorcinol and chloro-substituted resorcinols in an aqueous acid solution of (a) formaldehyde having a pH value between 5 and 2.8, the molecular ratio of (a) to (b) being at least 6:1, heating the solution to a temperature of the order of 60 C. for a period of about one-half hour whereby there are formed precondensation products, adding animal fibers to the solution and subjecting the same to treatment therewith for about one-half hour while maintaining the temperature of the solution at 40-45 C., removing and drying the fibers and hardening at a temperature above 100 C.

5. A process according to claim 4 wherein the precondensation products are of formaldehyde and resorcinol.

6. A process according to claim 4 wherein the precondensation products are of formaldehyde and 1.3 dihydroxy 6. chloro-henzene.

7. In a process of improving the physical and chemical properties of wool, the steps which comprise dissolving (b) a compound of the class consisting of resorcinol and chloro-substituted resorcinols in an aqueous acid solution of (a) formaldehyde having a pH value between 5 and 2.8, the molecular ratio of (a) to (b) being at least 6:1, heating the solution to a temperature of the order of 60 C. for a period of about one-half hour whereby there are formed precondensation products, adding wool to the solution and subjecting the same to treatment therewith for about onehalf hour while maintaining the temperature of the solution at 40-45 C., removing, hydroextracting, and drying the wool and hardening at a temperature above 100 C.

8. In a. process of improving the physical and chemical properties of felt, the steps which comprise dissolving (b) a compound of the class coni sisting of resorcinol and chloro-substituted resorcinois in an aqueous acid solution of (a) formaldehyde having a pH value between 5 and 2.8, the molecular ratio of (a) to (b) being at least 6:1, heating the solution to a temperature of the order of 60 C. for a period of about one-half hour whereby there areformed precondensation products, adding felt to the solution and subjecting the same to treatment therewith for about 6 hours while maintaining the temperature of the solution at about 35 C., removing, hydroextracting, and drying the felt and hardening at about 105 C.

9. In a process of improving the physical and chemical properties of wool, the steps which comprise dissolving (b) a compound of the class consisting of resorcinol and chloro-substituted resorcinols in an aqueous acid solution of (a) formaldehyde having a pH value between 5 and 2.8 and in which at least 6 mols of (a) per mol of (b) are used, heating the solution at about 60 C. for approximately one-half hour whereby there are formed precondensation products, diluting the solution with water and adjusting the temperature to 40-45 0., adding wool thereto and treating the same about one-half hour, removing, hydroextracting, and drying the wool and hardening the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,395,733 Romer Nov. 1, 1921 2,234,138 Kritchevsky Mar. 4, 1941 2,240,388 Calva Apr. 29, 1941 2,348,602 Calva May 9, 1944 2,390,073 Calva Dec. 4, 1945

Claims (1)

1. A PROCESS OF IMPROVING THE PHYSICAL AND CHEMICAL PROPERTIES OF KERATINACEOUS ANIMAL FIBERS, WHICH COMPRISES THE STEPS OF TREATING THE FIBERS WITH A WEAKLY ACIDIC SOLUTION CONTAINING PRECONDENSATION PRODUCTS OF (A) FORMALDEHYDE AND (B) A COMPOUND OF THE CLASS CONSISTING OF RESORCINOL AND CHLORO-SUBSTITUTED RESORCINOLS IN THE PREPARATION OF WHICH AT LEAST SIX MOLS OF (A) PER MOL OF (B) ARE EMPLOYED, CENTRIFUGING THE THUS TREATED FIBERS AND DRYING THE SAME BY HEATING.