US2178759A - Circular knit goods comprising high tenacity rayon - Google Patents

Description

Patented NOVa7, 1939 uru'rm) STATES PATENT OFFICE CIRCULAR KNIT GOODS COIVIPRISING HIGH TENACITY BAYON Manfred Keller, Syosset, N. Y., assignor, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application June 25, 1936, Serial 2 Claims.

5 cular knit goods from high tenacity rayon.

Heretofore, sheer -circular knit fabrics, made from threads having adenierof less than 65, have been made from natural silk threads. Materials other than natural silk could not be used satisfactorily for the production of sheer knit goods of this type on circular knitting machines since they lacked the required strength. Due to the sheemess of the knit goods, a high dry tenacity is required in order ,that the fabric have the required durability. High dry' strength has also been required of the threads knitted intofabric since the threads during knitting are subjected to severe strains and abrasion as they are passed through the needles. Additionally,'sheer circular knit goods must be made from threads having ahigh wet strength in order to withstand washing with water either by hand or by machine. Ordinary rayon of normal tenacity, as compared with high tenacity rayon, is not satisfactory for the production of sheer circular knit goods, since the strength is too low for the production of sheer fabrics. 4 I

It is therefore an object of the present invention to produce sheercircular knit goods from yarn consisting solely of rayon, for example, viscose rayon.

It is another object of the present invention to produce sheer circular knit goods from yarn having a denier of less than 65 and preferably below '50, said yarn consisting of high tenacity rayon, preferably viscose rayon.

Other objects of the invention will appear hereinafter.

In accordance with the present invention, cirq'i cular knit goods oifthe sheer type can now be 2.5 grams per denier. .Such high tenacity rayon will have a tenacity when wet at room temperature of at least 1.5 grams per denier.

High tenacity rayon adaptable for use in ac- Renewed October 28, 1938 cordance with this invention may be obtained by the process described and claimed in the United States Patent No. 2,133,714 of Harold H.

Parker, although other types of high tenacity rayon may also be used.

Ascompared with the figures given above for high tenacity rayon, ordinary rayon sold on the market for use in the knitting and weaving industry has a dry tenacity at room temperature of about 1.6 grams per denier and a wet tenacity of about 0.8 gram per denier. Thus the dry and wet strength of high tenacity rayon preferably having a dry tenacity of 3 grams per denier, or more, and wet strength of over 1.5 grams per denier, is far greater than that of ordinary rayon. Thedry and wet tenacity of high tenacity rayon compares veryfavorably with that of real silk, making possible the replacement of real slik in sheer circular knit goods made from low denier threads, for example from threads having a denier of approximately 50 or less.'

High tenacity rayon exhibits a lower wet and dry elongation than ordinary rayon and a much higher elasticity, having consequently a less permanent deformation, fabrics made therefrom retaining their shape for a much longer period of time and having a longer useful life. The high tenacity threads used in the production of circular knitted goods of the sheer type should not have a percentage elongation in excess of and preferably not in excess of 15%.

The following examples illustrate types of high tenacity rayon threads suitable for use in the manufacture of rayon circular knit goods.

Example I 50' denier-20 filament regenerated cellulose threads produced by the viscose process, twisted to 6 turns per inch, and having a tenacity when dry and at room temperature of 2.5 grams per denier, and an elongation of 15%, are knitted in a circular knitting machine to produce derwear fabric.

Example 11 Two 30 demer-iz'mament regenerated cellulose threads produced by the viscose process, 5

twisted 6 turns per inch, and having a tenacity when dry and at room temperature of 3 grams per denier, and an elongation of 14% are plied with a reverse twist of turns per inch. The plied thread is knitted, on a circular knitting machine, to produce sheer underwear fabric.

The underwear fabrics produced in accordance with the above three examples are found to satisfactorily resist wear and washing. The wearing qualities'of sheer circular knit goods produced from rayon having a high tenacity and low elongation compare very favorably with real silk.

The underwear fabrics produced from high tenacity-low elongation rayon have a much softer feel and handle than similar fabrics produced from ordinary rayon.

Elongation (unless otherwise qualified) as used throughout the specification, means percentage elongation of the dry thread at the breaking point when tested at room temperature.

Tenacity or its equivalent (unless otherwise qualified), as used throughout the specification and claims, signifies the maximum load that can be put on the dryer wet thread at room temperature.

Both dry tenacity and dry elongation of high tenacity rayon thread may be determined by the following test:

The thread is reeled under uniform tension in 450 meter skeins; these skeins are conditioned for three hours in an atmosphere maintained at 60% relative humidity and 75 F.; the skeins are then weighed to determine the denier which is defined as the weight in grams of 9000 meters.

The tests for determining tenacity and elongation are made on a Suter single strand strength and elasticity tester with an oil plunger controlled pull. The rate of fall of the plunger is 1 foot per minute, and the distance between the clamps is adjusted for an 18" length of yarn. In making the dry test, five single strands from each of the above skeins are tested separately.

These are clamped in the tester and stretched until the yarn breaks. Both the breaking load in grams and the percentage elongation may be read directly from scales on the machine. Grams per denier are obtained by dividing the scale reading in grams by the denier of the thread.

The average of 50 dry. breaks on threads selected at random is considered to be the tensile strength for any given 100 pound lot of yarn Where methods of testing other than those specifically referred to herein are ,used, different numerical results may be, obtained, but the relative improvement over the prior art will be of the same order regardless of the method oftesting used.

Since the invention is capable of considerable modification and variation from the details given above, any change which conforms to the spirit of the invention is intended to be included in the scope of the appended claims,

I claim:

'1. As a' new article of manufacture, sheer circular knit goods comprising high tenacity rayon thread produced from viscose, said thread having a denier of less than 65, a percentage elongation not in excess of 15, and a wet tenacity of at least 1.5 grams per denier, said thread being composed of a plurality of fine filaments twisted together with about 6 turns per inch.

2. As a new article of manufacture, sheer circular knit goods comprising high tenacityrayon plied thread produced from viscose, said thread.

having a denier of less than 65, a percentage elongation not in excess of 15, a dry tenacity of at least 3 grams per denier, said plied thread constructed of two multifilament threads each twisted at about 6 turns per inch and the two threads plied with a reverse twist of about 10 turns per inch, and a wet tenacity. of at least 1.5 grams per denier.

MANFRED KELLER.

CERTIFICATE OF CORRECTION. Patent No. 2,178,759. November 7, 1939.

MANFRED KELLER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 55, claim 2, before "said" insert the words and comma and a wet tenacity of at least 1.5 grams per denier, lines 39 and b0, same claim, strike out the comma and words and a wet tenacity of at least 1. 5 grams per denier"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day of December, A. D. 1959.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.