US2491454A - Nonslip fabrics and method of preparation thereof - Google Patents

Description

Patented Dec. 13, 1949 NONSLIP FABRICS AND METHOD OF PREPARATION THEREOF Alden D. Nate, Stamford, Conn., assignor to a corporation of Maine American Cyanamid Company, New York, N. 1.,

No 1mm. Application October 4,1944, Serial No. 551,233

6 Claims. (Cl. 117-138.

This invention relates to the stabilization of woven or knitted fabrics to prevent slippage of one thread or fiber over another, and is directed particularly to fabrics composed of or containing synthetic fibers having a hard and smooth surface wherein thread slippage is a particularly serious problem. The invention will be described and illustrated with reference to fabrics composedof or containing nylon threads, which normally have hard and smooth surfaces that cause themto slip readily, but it should be understood that the principles of the invention are applicable to fabrics composed-of or containing other synthetic fibers having similar characteristics.

Considerable difliculty has heretofore been experienced with woven and knitted fabrics composed Of or containing hard synthetic fibers of the type of nylon threads because of the ease with which the threads will slip out of place when the fabric is pulled or rubbed. This is most noticeable in the slippage of the warp threads over the filling threads in woven fabrics. It is particularly troublesome in marquisette insect netting and screen cloth of the types that are now used by the armed forces in the South Pacific and other tropical and semi-tropical areas. Nettings and screens composed of synthetic fibers such as nylon having a hard finish are preferred over cotton and other natural fibers for service in these areas, but the meshes of the nettings are readily enlarged by thread slippage to the point where insects can easily penetrate the screen. It is a principal object of the present invention to pro-' adverse service conditions.

Another important field of application of the principles of the invention is in preventing runs in knitted fabrics, such as nylon stockings. When fiber slippage is prevented in fabrics of this class the breaking of a single thread is not so likely to cause a run or "ladder" as is the case in ordinary nylon stockings, since the threads are securely fastened to each other at their points of intersection.

I have found that slippage of hard and smoothsurfaced threads of the type of nylon is effectively prevented to a remarkable degree when the fabric contains a cured alkylated methylol melamine, which functions to bind the fibers together and thus to stabilize the fabric. I have found that this class of materials has unique properties as a binding or stabilizing agent for hard synthetic fibers of the type ofnylon threa s. and for this purpose it gives results that are far superior to those obtained with ureaformaldehyde resins, thermoplastic resins, and other types of binding agents. Accordingly, my invention in its broadest form consists in the application to fabrics of the class described of an alkylated methylol melamine resin under conditions such that the threads of the fabric become coated and/or impregnated with the resin in its cured and water-insoluble condition. The production of treated fabrics containing the cured resin in quantities such as to prevent slippage of the threads constitutes a further object of my invention, and is included within the scope thereof.

Alkyl-ated or alcohol-reacted methylol melamines are resin-forming materials obtained by reacting methylol melamines with aliphatic primary monohydric or polyhydric alcohols in the presence of small quantities of acidic catalysts. It is generally understood that the reaction takes place between the alcohol and one or more methylol groups of the methylol melamine with the elimination of water and the formation of an ether, and therefore the final products are proper- 1y designated as alkylated methylol melamines. The term alcohol-reacted methylol melamines, of course, defines the same materials in terms of their method of manufacture. This class of materials has previously been applied to wool and cotton fabrics to prevent shrinkage therein, but they have never previously been applied to nylon and similar fabrics for the purpose of fiber stabilization.

Although a wide variety of alkylated methylol melamines is available for use in practicing my invention, I have found that the best results are obtained when the water-soluble type of alkylated methylol melamine is employed. It is a known fact that water-insoluble alkylated methylol melamines can be prepared by reacting almost any aliphatic primary monohydric alcohol with a methylol melamine containing from 2-6 methylol groups in the presence of an acid catalyst such as hydrochloric acid, and these products have been used in the preparation of lacquer surface coatings. However a class of water-soluble alkylated methylol melamines has recently been developed by carrying out the same type of condensation under carefully controlled conditions, using a lower aliphatic monohydric alcohol such as methyl or ethyl alcohol or a lower polyhydric alcohol such as ethylene glycol or di-ethylene glycol. The latter class of resin-forming materials is greatly superior for the purposes of the acorns present invention since it avoids undue stiflening of thewoven fabrics when applied in the amounts necessary toobtain satisfactory stabilization. Moreover, the water-soluble alkylated methylol melamines and particularly the water-soluble methylated methylol melamines are much more eifectlve in preventing slippage of one fiber over another than are the corresponding water-insol-.

uble resins. and therefore the water-soluble variety constitutes the preferred class of materials used in practicing m invention.

The exact quantity of resin which will produce optimum results will vary with the type. of fabric and with the degree of slipp e prevention that may be desired. In general, I have found that amounts of about 3% f the resin, based on the dry weight of the fabric, are sufficient with very light fabrics to produce an appreciable and-inmany cases a. satisfactory stabilization, whereas quantities of more than 20% are usually unnecessary. I have obtained very satisfactory results using about 6 to 10% of water-soluble methylated methylol melamine, based on the dry weight of the cloth, and therefore this may be taken as the preferred quantities for use in practicing my invention. The resin is preferably applied in the form of a relatively dilute aqueous solution.con-

taining about 8 to 20% of the resin together with a a curing accelerator to assist in curing or polymerizing the resin to its insoluble condition after tts application to the fabric. Ordinarily about 0.35% of a mixture of equal parts of diammonium hydrogen phosphate and hexamethylene tetramine, based on the weight of the resin, is used for this purpose.

The water-soluble methylated methylol melamine which I employ is prepared by reacting a substantially monomeric methylol melamine with methanol under slightly acid conditions with careful temperature control. The following procedure has been used with success in preparing this resin:

1 mol of melamine is mixed with 3.3 mols of aqueous 37% formaldehyde previously adjusted to a pH of approximately 8.0, the temperature being raised to 70 C. and maintained at this point until a clear solution is obtained. The solution is then immediately cooled and allowed to set and the mass is broken into small pieces. and dried by circulating warm air at a temperature not exceeding 55' C.

The resulting dried powder is added to twice its weight of 95% methanol containing 0.5% l of oxalic acid crystals, based on the. weight of the methylol melamine. The mixture is heated to 70 C. and held at this temperature for approximately minutes, or until a clear solution is obtained, whereupon it is immediately neutralized by the addition of sufllcient sodium hydroxide solution to raise the pH to approximately 9.0. The neutralized reaction mixture is then evaporated to 80% solids under reduced pressure so that the emperature does not rise' above 50 C.

It should be understood that the invention is not limited to the ratios of formaldehyde, melamine and methanol described in the foregoing example. 0n the contrary, from 2 to 6 mols of formaldehyde may be combined with each mol of melamine, and the resulting methylol melamine may be reacted with from 2 to 6 mols of methanol. The term water-soluble methylated methylol melamine therefore describes any water-soluble product prepared by reacting methanol with a substantially monomeric meth- 1s 8. A method of stabilizing marquisette fab- '4 ylolmelaminecontainingztoemolsofoombined formaldehyde under conditions such that I a water-soluble reaction product is formed.

In addition to the advantages enumerated above, it is a further important feature of my invention that it can be applied to grey cloth or as it comes from the loom. One advantage of applying the resin to the cloth at this stage of ment to stabilize the fabric.

The fabrics to be stabilized may be impregnated with the resin solution by any suitable procedure such as those now in commercial use. Preferably the process is applied by running the fabric through the resin-containing liquor in a 2 or a 3 bowl mangle, which is usually mm in tandem with a tenter frame for drying the fabric to the proper width. The mangle bowls are preferably rubber, but may be of any conventional design. After drying, the fabric is heat-cured by any of the usual methods, such as by running it through a loop dryer for 3 to 5 minutes at 300 1''. Following this treatment the fabric may be given a short wash in a dilute solution of soap and sodimn carbonate. if desired, although the washing is not necessary and is frequently omitted in the treatment of some types of fabric.

As a specific example the following is cited: 15,000 yards of nylon marquisette insect netting as it came from the loom, without scouring,

were treated by the process of my invention. The treating bath was made up by dissolving 140 lbs. of methylated methylol melamine, prepared as described above, together with 4 lbs. of the above-described curing accelerator in gals. of warm water and adding pigment colors to produce the desired shade. The pickup at the mangle was approximately 30%, and therefore the fabric contained 4% of the methylated methylol melamine resin. The impregnated fabric was passed through a loop drier at 300' F., using a drying time of approximately 4 minutes, after which it was found that slippage between the warp and filling threads was effectively prevented even after three rayon launderings. Attempt to displace the filing threads in the treated and cured fabrics by pulling them with the fingers were unsuccessful, whereas the unstabilized fabrics were readily distorted by this treatment.

What I claim is:

l. A method of stabilizing woven net fabrics composed of hard-finish nylon threads which comprises impregnating said fabrics with an aqueous solution of about 13-20% of their weight of a water-soluble alkylated methylol melamine in an uncured condition, and subsequently heating the impregnated fabrics to convert the impregnating agent into a cured resinous binder.

2. A method of stabilizing woven 'net fabrics composed of hard-finish nylon threads which comprises impregnating said net fabrics with an aqueous solution of about 3-20% of their weight of a water-soluble methylated methylol melamine in an uncured condition, and subsequently heating the impregnated fabrics to convert the impregnating agent into a cured. resinous binder.

rics composed of hard-finish nylon threads which comprises impregnating said fabrics with an aqueous solution of about 6-10% of their weight of a water-soluble alkylated methylol melamine in an uncured condition, and subsequently heating the impregnated fabrics to convert the impregnating agent into a cured, resinous binder.

4. A method of stabilizing marquisette fabrics composed ofhard-finish nylon threads which comprises impregnating said fabrics with an aqueous solution of about 6-10% of their weight of a water-soluble methylated methylol melamine in an uncured condition, and .subsequently heating the impregnated fabrics to convert the impregnating agent into a cured resinous binder. I

5. A woven net fabric composed of nylon threads, said fabric being stabilized against thread slippage by a content of about 3-20% of its weight of a cured alkylated methylol melamine resin, said resin having been applied uniformly to the fabric as an aqueous solution of REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS Number Name Date 2,329,622 Johnstone Sept. 14, 1943 2,340,359 Young Feb. 1; 1944 2,343,039 Smith Feb. :29, 1944 2,343,093 Smith Feb. 29, 1944 2,370,362 -'Light Feb. 27, 1945