US2689806A - Process for resin treating wool textile material - Google Patents

Description

Patented Sept. 21, 1954 PROCESS FOR RESIN TREATIN G WOOL TEXTILE John N. Dalton, Providence, R. 1., and William B. Kaupin, Lawrence, Mass., assignors to Pacific Mills, Lawrence, Mass, a corporation of Massachusetts No Drawing. ApplicationFebruary 3, 1953, Serial No. 334,978

The present invention relates to resin treat- :ment of wool orwool-blend textile material, such as wool or part-wool raw stock, yarn or fabric (hereinafter referred to as wool material). An object is to provide a process for producing resin- Claims. (01. 117- 93) treated textile products which in the form of fabric or fabricated articles (woven or knitted) retain substantially the soft hand, tensile strength and resistance to wear of comparable products without our treatment and yet have a durable resistanceto shrinkage when laundered.

Although numerous processes have been suggested for resin treating wool to produce a fabric having a reduced tendency to shrink when laundered, the resulting fabrics have lacked, in whole or in part, some of those characteristics which are required for a satisfactory commercial wool fabric, principally the softness and flexibility, namely the soft feel and hand of the untreated fabric. The conventional resin application procedure, which consists essentially of im .pregnating from a water solution of the resinforming materials, squeezing to remove excess liquor, drying by convection heat, and curing or baking by convection heating at temperatures above 212 F., produces afabric'whi'ch has many disadvantages. The unavoidable hot air drying step, in this processing of a wool material saturated with the water soluble resin-forming material, such as certain amine-aldehyde resins, adversely afiects the distribution of the resin within the material. External heating dries the surfaces first and moisture from the interior is forced through the relatively dry outer zone. The removal of water by this slow diffusion .mechanism results in migration of the resinforming material to the surfaces and deposition of resin on the surfaces. This resin concentrated at the surface or periphery is heat hardened or cured by the necessary heating at temperatures substantially above 212 F. An attendant effect in the curing operation is exposure 1 of the dry wool to formaldehyde vapor, a byy product of amine-aldehyde resin condensation at elevated temperatures, by which the woolis em-- brittled. The insoluble surface deposition of resin and the embrittling effect of dry heat and formaldehyde result in decreased fabric elasticity and consequently a decrease in tensile strength. The fabric is boardy or stiif. has a .harsh or dry handle and shows white rubs or ""chalks when rubbed with the fingernail. Another disadvantage is lack of permanency, i. e., the resin-treated wool fabric, especially a woolen fabric, has limited durability of shrinkage control in repeated wear and laundering.

Our invention eliminates the foregoing disadvantages. Our invention is applicable not only to fabric but also to wool orpart-wool textile material in other forms, e. g., raw stocks, yarn, rovinggtop, etc.

In the practice of our invention we impregnate and swell a wool, or part-wool, textile material witha solution or dispersion of certain water-soluble resin-forming materials in a polar liquid, preferably water, and, after squeezing out excess liquid,,we heat the wet material throughout from surface to surface uniformly and so rapidly that the resin-forming materials on the wool have no time to migrate appreciably and do not so migrate and the resin distribution remains in effect homogeneous throughout from surface to surface as the resin-forming materials are polymerized or cured. This we carry out by 'a single-step heating of the wet material *by a high frequencyele'ctri-c field for from about 0.3 to 5 minutes while the material contains, throughout the heating and curing step, at least more than about 20% of its weight of water, by

which we accomplish this uniform, practially instantan'eous heating of the wet material, accompanied by insolubi'lization and curing of the resin, at external surface fabric (yarn or raw stock, etc.) temperatures at or below 212 F. Our process produces a higher temperature inside the material than at its surface, a swelling of the wool substance, a tendency of the resin-forming materials to migrate inwardly rather than outwardly and an increased chemical reactivity of all materials present.

Under these conditions the resin-forming material is driven further into the wool substance and is deposited there byi'ts further condensation and its reaction with the wool substance. During the high frequency heating and curing of the textile material its liquid content is not reduced 'below about 20% of the dry weight of the material. Moisture reduction during curing desirably is kept to a minimum, as the less the moisture loss, the more rapid the cure, and usually the liquid content is not substantially reduced during curing, i, e., no substantial drying occurs.

We thereby prohibit the concentration of resin at -or near the surfaces of the fibers, yarns or fabric, etc, which we have found to be a cause of the harsh finish of wool 'tabricsas previously treated with resin. We provide an increased and more uniform penetrationof the resin-forming materials into the wool substance, main- 'taintheresin in such condition until it reaches its full cure.

We effect such ou-re at an external temperature of the fabric, yarn, etc, under 212 F.

in a single heating step without any additional curing or baking operations.

We obtain a resin-treated Wool material which is homogeneous from surface to surface. The finished fabric whether made from. material resintreated by our process, or resin-treated in fabric form, has the softness, flexibility, tensile strength and wear resistance of a fabric of untreated material and has the desired improvement in dimensional stability, i. e., resistance to shrinkage on repeated laundering. The durability of shrinkage control of fabrics treated by the method of this invention (or made from materials so treated) is superior to that of comparable fabric treated by conventional processes. The heating step of our process is self-limiting in that generation of heat in the material is dependent upon presence of liquid therein. While sufiicient heating of the resin-forming materials to effect a complete cure will occur without reducing the fabric liquid content below about 20%, and usually with no substantial reduction of the liquid content, continued application of the high frequency field will do no harm but will drive off further liquid, reducing the conductivity of the material and thus decreasing the generation of heat therein.

The resin-forming materials in the impregnating bath may be either in the monomeric state or may be partially condensed to a low-molecularweight reaction product which is capable of being dissolved or dispersed in the liquid medium. By solution as used herein we include such dispersions.

The resin-forming materials which we employ are the methylolmelamines and their lower alkylated derivatives and co-condensation products, or the corresponding unreacted materials, e. g., melamine and formaldehyde. Within the group we prefer, for shrink-proofing wool, the methylolmelamines, including the alkylated methylolmelamines, with the addition thereto of urea, or its equivalent, e. g., thiourea, hydroxylamine, or guanidine. Particularly good results are obtained with urea and methylated methylolmelamine. All of these, including the pre-condensates, are for convenience referred to herein as resin-forming materials.

In our process the resin-forming materials are chemically combined with the wool.

The resin concentration in the bath and the amount of liquid taken u by the textile material are so regulated as to incorporate in the material about 5 to of resin solids by weight of the material.

The following examples illustrate typical applications of the invention:

EXAMPLE I A wool fabric was first dyed with an acid dye and the final rinse adjusted so that the fabric retained about 4% of sulfuric acid. The fabric was then passed through a bath composed of an aqueous solution containing by weight 14% methylated methylolmelamine, 5% urea and 5% alpha trioxyrnethylene and a non-ionizing wetting agent such as polymerized ethylene oxide. A three roll mangle allowing two dips and two nips was utilized and the mangle pressure was so regulated that the fabric retained 60% on its own dry weight of the impregnant after the final squeeze. The concentration of the methylolmelamine in the impregnating bath was adjusted so that the resin picku was 5.5% solids on the weight of the fabric. The fabric was then cured by passing it into a high frequency field having a frequency of 10' megacycles. The Wet material was heated for 4 minutes at 190-212 The resin-forming materials were cured so rapidly that they did not migrate to the surfaces of the fabric but remained uniformly distributed throughout the fabric, which remained wet throughout the operation. The treated samples and controls were allowed to remain under normal room conditions until equilibrium was reached.

The treated fabric had the same softness, flexibility (hand and feel) and tensile strength as the fabric before treatment. It had no appreciable surface resin which in many treated wool fabrics causes stiffness or a boardy handle, but the resinous materials were homogeneous from sur face to surface of the fabric.

Samples of the treated fabric and similarly dyed, but otherwise untreated, control samples were subjected to standard wool washing tests (CCC-T 191a, Fed. Spec. for Textiles, sec. IV, part 5, par. XIV). The treated specimens were found to retain fabric character and dimensional stability after repeated laundering. The shrinkage of the warp, for examplegafter eight launderings was found to be 0.3%, while the shrinkage of the warp of the control samples after the same eight launderings was found to be EXAMPLE II Samples of wool fabric were acid dyed with 1% and 3% Pontacyl Green SN, Color Index 737, by conventional practice and the final rinse adjusted so that the fabric contained about 3 to 4% sulfuric acid. The fabrics were dried and run through an aqueous solution containing by weight 11% hexamethylohnelarnine, 4% urea, and 4% alphatrioxyinethylene. A three roll mangle was used and the goods given two dips and two nips; the final squeeze was regulated so that the fabric retained 50% of the impregnating solution. The wet samples were then cured while wet by subjecting them directly to a high frequency field having a frequency of 20 megacycles for a period of three minutes at a temperature of to 210 F. in an aqueous and formaldehyde vapor atmosphere.

Samples of the treated fabric and similarly dyed but otherwise untreated control samples were subjected to a standard wool washing test as in Example I. The warpwise shrinkage of the treated specimens after 8 washings was found to be 1.3%, as contrasted with 19.8% for the controls. The corresponding figures for filling wise shrinkage were 0.8% for the treated samples and 14.3% for the controls.

The treated specimens of Examples I and II did not bleed in laundering or stain multi-fiber test cloth and after eight standard launderings were found to retain their brilliance and depth of color shade. The controls bled badly, were seriously altered in color after three standard launderings and would be considered unservicea-ble, from a color standpoint, after five launderings. The treated samples were given a standard alkaline perspiration test and were not altered in shade and did not produce any bleeding on the white test cloth. The controls, however, became streaky, changed in shade and bled badly onto the test cloth. The treated specimens showed no surface marking off or boardiness.

EXAMPLE III A light woolen undyed ribbed flannel (A) was impregnated as described in Example I and squeezed to leave on the fabric sufficient aqueous solution to provide. 515% methylated methylolmelamine, 1.4.% urea, sufficient formaldehydexto effect a combined ratio of HCHO :to urea of 1:2 and 0.28% of hydroxylamine hydrochloride neutralized with ammonia, each by weight on the fabric. The cloth wasthen cured by subjecting it to a high frequency field in a model 1513 Radio Corporation of America radio frequency generator by placing eight thicknesses of the cloth (60" wide) between the aluminum electrode surfaces which were 60" x 48" in size and spaced 4. apart. The generatorwas adjusted to provide the following conditions.

Grid current 420 milliamper'es Filament volts 21 Plate current 3.5 to 3. 8 tamperes Plate voltage 8 kv.

Power used 28 kilovolt amperes curing by convection heating. Both samples were then subjected to a series of standard CCC-T 191d launderings and the wool shrinkage determined after-each laundering with the results shown inthe following table, from which it :is evident that specimenA treated bythe processof this invention showed a greatly increased resistance to launderings as comparedwith specimen B.

Warp felting shrinkage '6 sec. IV, part 5, par. XIV. After three such washing tests, the shrinkage in the control, or untreated, tube was 36.9% whereas it was only 8.5% in the treated tube.

EXAIWPLE V A sample of worsted yarn was resin-treated and cured as in Example IV.

Tubes knitted from the treated yarn and from untreated yarn of the same lot and subjected to washing tests as described showed a shrinkage in the control of and in the treated tube of 8%.

The tensile strengths of both warp andfilling of thesamples treated by the process of the inventionwereas goodasthose of the controls in all the foregoing examples and in some specimens they were noticeably better.

We prefer to provide a catalyst for the resin forming reaction which may be any usual vapor- :phase or liquid-phase catalyst, e. g., an acid such as sulfuric, phosphoric, acetic, formic, tartaric, maleic or itaconic, or an acid yielding salt, e. g., ammonium gluconate. We prefer to incorporate the catalyst as residual acid or acid salt remaining from the dyeing operation where this is practicable, or by padding with such acid, thus avoiding the necessity of including a catalyst as aningredient in'the impregnating bath. The acid should be present when the fabric is heated, irran amountsufficient to provide a pH of about 2 to 5'.

We use the term high frequency in its generally accepted usage in the art; for our purposes frequencies of the order of about 5 to megacycles appear to be suitable.

The method of this invention makes it possible to resin-treat loose wool, top, or yarn which NUMBER OFCCQ-T 191a LAUNDEBINGS l 2 a 4 5 s 7 s 7.8 11.8 15.7 18.6 22.1 -4.1 26.1 27.2. 28.4 29.9 30.7 0.3 -0.4 0.6 0.2 -o.s 0.5 -1.1 -0.s 0.7 0.9 1.1 0.2 0.2 0.5 2.3 4:9 5.2 0.4 8.3. as 10.6 11.9

A minus sign indicates stretch.

EXAMPLE IV may be subsequently processed to produce a d1- ting agent such as polymerized ethylene oxide.

After impregnation, the top wassqueezed with a tworoll padder and the mangle pressure was regulated so that the top retained about 70% of 'its.

dry weight of the impregnation liquor. The top was then wrapped in a white canvas cloth and passed into a high frequency field having a frequency of 10 megacycles. The top was heated for 3 minutes at 190 to 212 F. to cure the resin during which time no substantial drying was effected. The treated'top hadmuch the same'softness and flexibility as the original. Samples of treated and untreated top from the samel'ot were processed into 1/20s yarn and knit Iintosajtube of approximately 3" inc. Brinton knitting machine which had a 4" head with 200 latch needles. Tubes of the treated and untreated 'yarns, respectively, were relaxed by soaking in Very dilute solution (0.05%) of polymerized'ethylene oxide wetting agent for 1 hour at 90 The tubes were marked 13" .in the long axis by .a-standard markingdevice and subjected tostandard wool washing testCCC-T 191a, Fed Spec. for Textiles,

mentionally stable fabric. By prior methods, loose wool, top or yarn impregnated with resin, convection dried, and heat cured does not produce a stable or washable fabric. This is due to the rigidity and the surface location of the resin on the yarn, resulting in its removal by the necessarily drastic subsequent manufacturing operations, e. g., spinning and weaving.

The present application is a continuationinpart of our prior application Serial No. 215,873, filed March 15, 1951, now abandoned, which is a continuation-in-part of our prior application Serial No. 9,346, filed February 18, 1948, now Patent No. 2,545,450.

We claim:

1. The method of treating wool material to enhance its dimentional stability under laundering conditions whilepreserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated wool material, vhich comprises impregnating the wool material with an aqueous solution of about 5% to 10% of the weight of the wool-material of resin-forming materials comprising a methylolmelamine, and converting said resinforrning materials to cured resinous condition, wihile said solution is maintained substantially uniformly distributed through the whole thickness of the wool material, by exposing the wet impregnated material to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the wool material above about 20% of the dry weight of the wool material and main taining the external surface temperature of the Wool material not above 212 F.

2. The method of treating a wool fabric to enhance its dimensional stability under laundering conditions while preserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated fabric, which comprises impregnating the fabric with an aqueous solution of about 5% to 10% of the weight of the fabric of resin-forming materials comprising a methylolmelamine, and converting said resin-forming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the whole thickness of the fabric, by exposing the wet impregnated fabric to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the fabric above about 20% of the dry weight of the fabric and maintaining the external surface temperature of the fabric not above 212 F.

3. The method of treating wool material to enhance its dimensional stability under laundering conditions while preserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated wool material, which comprises impregnating the wool material with an aqueous solution of about 5% to 10% of the weight of the wool material of resin-forming materials comprising an alkylated' methylolmelamine, and converting said resinforming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the whole thickness of the wool material, by exposing the wet impregnated material to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the wool material above about 20% of the dry weight of the wool material and maintaining the external surface temperature of the wool material not above 212 F.

4. The method of treating a wool fabric to enhance its dimensional stability under laundering conditions while preserving its properties of fiexibilit tensile strength and soft hand and feel substantially equal to those of the untreated fabric, which comprises impregnating the fabric with an aqueous solution of about 5% to 10% of the weight of the fabric of resin-forming ma- 5i and maintaining the external surface temperature of the fabric not above 212 F.

5. The method of treating wool material to enhance its dimensional stability under laundering conditions while preserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated wool material, which comprises impregnating the wool materialwith an aqueous solution of about 5% to 10% of the weight of the wool material of resin-forming materials comprising a methylolmelamine, urea and formaldehyde, and converting said resin-forming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the whole thickness of the wool material, by exposing the wet impregnated material to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the wool material above about 20% of the dry weight of the wool material and maintaining the external surface temperature of the wool material not above 212 F.

6. The method of treating a wool fabric to enhance its dimensional stability under laundering conditions while preserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated fabric, which comprises impregnating the fabric with an aqueous solution of about 5 to 10% of the weight of the fabric of resin-forming materials comprising a methylolmelamine, urea and formaldehyde, and converting said resin-forming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the whole thickness of the fabric, by exposing the wet impregnated fabric to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per' second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the fabric above about 20% of the dry weight of the fabric and maintaining the external surface temperature of the fabric not above 212 F.

7. The method of treating wool material to enhance its dimensional stability under laundering conditions while preserving its properties of flexi-' bility, tensile strength and soft hand and feel substantially equal to those of the untreated wool material, which comprises impregnating the wool material with an aqueous solution of about 5% to 10% of the weight of the wool material of resin-forming materials comprising an alkylated methylolmelamine, urea and formaldehyde, and converting said resin-forming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the Whole thickness of the wool material, by exposing the wet impregnated material to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the wool material above about 20% of the dry weight of the wool material and maintaining the external surface temperature of the wool material not above 212 F.

8. The method of treating a wool fabric to enhance its dimensional stability under laundering conditions While preserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated fabric, which comprises impregnating the fabric with an aqueous solution of about to of the weight of the fabric of resin-forming materials comprising an alkylated methylolmelamine, urea and formaldehyde, and converting said resinforming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the whole thickness of the fabric, by exposing the wet impregnated fabric to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the fabric above about 20% of the dry weight of the fabric and maintaining the external surface temperature of the fabric not above 212 F.

9. The method of treating wool material to enhance its dimensional stability under laundering conditions while preserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated wool material, which comprises impregnating the wool material with an aqueous solution of about 5% to 10 of the weight of the wool material of resinforming materials comprising a methylated methylolmelamine, urea and formaldehyde, and converting said resin-forming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the whole thickness of the wool material, by exposing the wet impregnated material to a high frequency electric field having a frequency of the order of about 5 to 50 megacycles per second for about 0.3 to 5 minutes to heat it sub- 10 stantially uniformly from surface to surface, while maintaining the liquid content of the wool material above about 20% of the dry weight of the wool material and maintaining the external surface temperature of the wool material not above 212 F.

10. The method of treating a wool fabric to enhance its dimensional stability under laundering conditions while preserving its properties of flexibility, tensile strength and soft hand and feel substantially equal to those of the untreated fabric, which comprises impregnating the fabric with an aqueous solution of about'5% to 10% of the weight of the fabric of resin-forming materials comprising a methylated methylolmelamine, urea and formaldehyde, and converting said resinforming materials to cured resinous condition, while said solution is maintained substantially uniformly distributed through the whole thickness of the fabric, by exposing the wet impregnated fabric to a high frequency electric field having a frequency of the order of about 5 to megacycles per second for about 0.3 to 5 minutes to heat it substantially uniformly from surface to surface, while maintaining the liquid content of the fabric above about 20% of the dry Weight of the fabric and maintaining the external surface temperature of the fabric not above 212 F.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,405,037 Hsu July 30, 1946 2,545,450 Dalton Mar. 20, 1951

Claims (1)

1. THE METHOD OF TREATING WOOL MATERIAL TO ENHANCE ITS DIMENTIONAL STABILITY UNDER LAUNDERING CONDITIONS WHILE PRESERVING ITS PROPERTIES OF FLEXIBILITY, TENSILE STRENGHT AND SOFT HAND AND FEEL SUBSTANTIALLY EQUAL TO THOSE OF THE UNTREATED WOOL MATERIAL, WHICH COMPRISES IMPREGNATING THE WOOL MATERIAL WITH AN AQUEOUS SOLUTION OF ABOUT 5% TO 10% OF THE WEIGHT OF THE WOOL MATERIAL OF RESIN-FORMING MATERIALS COMPRISING A METHYLOLMELAMINE, AND COVERTING SAID RESINFORMING MATERIALS TO CURED RESINOUS CONDITION, WHILE SAID SOLUTION IS MAINTAINED SUBSTANTIALLY UNIFORMLY DISTRIBUTED THROUGH THE WHOLE THICKNESS OF THE WOOL MATERIAL, BY EXPOSING THE WET IMPREGNATED MATERIAL TO A HIGH FREQUENCY ELECTRIC FIELD HAVING A FREQUENCY OF THE ORDER OF ABOUT 5 TO 50 MEGACYCLES PER SECOND FOR ABOUT 0.3 TO 5 MINUTES TO HEAT IT SUBSTANTIALLY UNIFORMLY FROM SURFACE TO SURFACE, WHILE MAINTAINING THE LIQUID CONTENT OF THE WOOL MATERIAL ABOVE ABOUT 20% OF THE DRY WEIGHT OF THE WOOL MATERIAL AND MAINTAINING THE EXTERNAL SURFACE TEMPERATURE OF THE WOOL MATERIAL NOT ABOVE 212* F.