US3308616A - Sewing thread - Google Patents

Description

3,308,616 Patented Mar. 14, 1 967 3,308,616 SEWING THREAD Kenneth Roger Williams, Landenherg, Pa., assignor to E. I. du Pont de Nemonrs and Company, Wilmington, Del, a corporation of Delaware No Drawing. Filed Mar. 8, 1965, Ser. No. 438,073 9 Claims. (Cl. 57-153) This invention relates to an improved sewing thread and to a process for its manufacture.

The object of the present invention is to provide an improved sewing thread of synthetic, polymeric composition that will perform satisfactorily at high sewing speeds.

This and other objects will become apparent in the course of the following specification and claims.

In accordance with the present invention, a novel sewing thread is provided, twisted from novel continuous filament yarn formed from a synthetic linear polymer, e.g. from polyacrylonitrile, a polyamide, a polyester or a polyolefin, and said yarn uniformly bearing on its surface from about 0.9% to about 11% by weight based on the weight of the said filament of a finish selected from the class consisting of (1) a mixture of from about by weight aluminum tristearate and 90% by weight dimethyl polysiloxane, (2) methyl-phenyl polysiloxane of about 18,000 cs. viscosity and (3) a mixture of about 40% by weight methyl hydrogen siloxane and 60% by weight dimethyl siloxane, the finish having been heat treated after the yarn bearing the finish has been twisted into thread. By being heat treated is meant that the finish is either melted upon the yarn, polymerized thereon as a result of a thermally initiated polymerization or simply subjected to the heating experienced in the usual heat setting of the twist. This thread is preferably of a denier less than about 1500 and has a twist multipler within the range of from about 2.4 to about 4.3 wit-h a coefiicient of kinetic friction at 600 F. within the range of from 0.1 to about 0.35. The filament yarn from which the thread is twisted preferably has a denier of from about 4 to about denier per filament, particularly from about 7 to about 16 denier per filament. The filaments are characterized by a flexural rigidity within the range of 2.7 10 and 14.0 10 gram (centimeter)? The novel yarns for this invention have a coefiicient of kinetic friction at 550 F. (measured prior to heat-treatment) within the range of from 0.10-0.38.

Finishes for this invention are those that permit the yarn filaments to retain their spatial integrity. Therefore, the filaments do not coalesce or become bonded to gether. It should 'be noted that the finish for this invention adheres to the filament preferably by a phase change, i.e., by either melting and then resolidifying, or by in situ polymerization. While many finishes are oper able for this invention, the preferable finishes are either aluminum tristearate in dimethyl polysiloxane or'the mixture of methyl hydrogen siloxane and dimethyl siloxane;

The coefiicient of kinetic friction for the sewing thread is determined to be the ratio of output-tension to input tension when the thread passes at 260 yards per minute over 170 of the surface of a smooth chrome cylindrical /s-inch diameter pin. The pin surface is electrically heated, and the temperature is adjustable from room temperature to more than 600 F. In determining coefiicient of kinetic friction for yarn (according to the above-specified method) the yarn is first twisted to give approximately the same twist multiplier found in synthetic sewing thread.

The fiexural rigidity for the filament is determined by the loop method according to P. W. Carlene (Journal of the Textile Institute Transactions T-l59, 1950). A single filament is formed into a 1.5-1.6 centimeter diameter continuous loop. The loop is flattened and then elongated (extended) for 2 millimeters at a rate of 0.64 centimeter per minute. The force in milligrams to so elongate the loop is multiplied by 2.72 10- to give the flexural rigidity in gram (centimeter)? This flexural rigidity is a function of filament denier, filament composition, and moment of inertia of the filament cross-section. This fiexural rigidity is directly proportional to denier and vto the moment of inertia. That is, as denier and moment increases, flexural rigidity increases. Of the polymers included within this invention, polyesters generally have the higher fiexural rigidity.

The following examples serve to illustrate this invention, and are not intended to limit it in any manner.

Example I A three-ply sewing thread, denier per ply, and twisted 228 x 172 for a twist'multiplier of about 4.3 is constructed of continuous, hexalobal, 16 denier per filament, filaments spun from a melt of polyhexamethylene adipamide. A finish, consisting of a 40% dispersion in water of the liquid mixture of about 60% liquid dimethyl siloxane and 40% liquid methyl hydrogen siloxane (commercially available under the trademark De Cetex 104 from the Dow Corning 'Corp. of Midland, Michigan) is applied to the yarn before twisting by passing the drawn yarn over the cylindrical surface of a metering roll which roll is rotatably sustained, partly submerged, in a bath of the dispersion. The yarn, hearing about 8.7% by weight finish is packaged to be twisted into thread. The fiexural rigidity of the filaments of the untwisted yarn is 8.6 10- gram (centimeter) and the coefficient of kinetic friction at 550 F. is about 0.19 (measured prior to the heat-treatment specified below).

After twisting the yarn to form a 240-denier thread, the twist is set, and polymerization of the siloxanes is accomplished, by placing a package of the thread in an oven at F. for about 3 hours. This thread is then packaged. The finish, now a solid (substantially waterfree), polymerized material, is retained on the thread after a normal boil-off scour. The coetficient of friction of the final thread at 600 F. is 0.27.

The sewing thread of the present invention, prepared as described above, is used on a Singer 600 Wl singleneedle, lock-stitch, sewing machine operating at 4500 stitches per minute and 12 stitches per inch to sew three layers of 9.4 ounces per square yard, 319 grams per square meter, 56 x 40 cotton duck. This sewing is with satisfactory results for beyond a five minute test interval. The thread remains intact, the stitching is uniform, and the layers are firmly sewn together.

When the same thread is used to sew 3 layers of 9.4 oz./yd. cotton duck on 2. Singer 600 W-21 machine operating at 4000 stitches per minute, the first break occurs after 4.35 minutes of sewing. In a comparative control A, wherein the yarn employed in the same sewing operation is identical except that the finish is applied to the thread (instead of being applied to the yarn before twisting), a break occurs in 1.48 minutes. The coefficient of kinetic friction. at 600 F. for this comparative control is 0.38.

Two other comparative controls, B and C are pre-. pared. Each is formed from round filament and each t'hread'is of'3 ply construction. Yarn characteristics are listed in Table I.

TABLE I Denier No.Fil. Denier Per Fil.

Flex. Rigidity 1 Geoff. Kin. Fric. 2

1 Gram (centimeter) 2 550 F.

3 Each yarn is coated with De Cetex 104 as taught above and twisted into thread. The twist multiplier, thread properties (including the thread coeificient of kinetic friction) and minutes to breaking when sewing comparative textiles at 4500 stitches per minute on a Singer 600 W1 machine are listed in Table II.

TABLE II Twist Thread Coetficient Minutes Control Multiplier Denier of Kinetic To Break Friction 1 Example II Aluminum tristearate, applied as a dispersion of solid aluminum tristearate (MP. 180 C.) in silicone oil (dimethyl polysiloxane) is substituted for the De Cetex 104 of Example I. Twist setting is done at 140 F. for three hours followed by heating at 248 F. for three hours to melt the finish on the thread. The yarn bears 5.0% by weight of the finish based on the weight of the yarn. The aluminum tristearate finish is observed to be a solid on the filaments of the twist-set thread, and the finish is retained on this thread after normal boil-off scour. The coefiicient of kinetic friction of the yarn, containing aluminum tristearate, is about 0.18 at 550 F. while the thread has a coeflicient of kinetic friction at 600 F. of 0.27. In sewing (a Singer W1 machine at 4500 stitches/min.) this thread breaks after 3.34 minutes of sewing.

Example 111 A De Cetex 104 finish is applied to a three-ply thread, 70 denier per ply, twisted 228 x 17Z for a twist multiplier of 3.7 and of round, S-denier filaments spun from a melt of polyethylene terephthalate in the same manner and in the same concentration as taught in Example I except that twist setting is done at 185 F. The flexural rigidity of the filaments is 2.77 10- gram (centimeter) and the coeflicient of kinetic friction of the thread is 0.27 at 600 F. The yarn bears 3.99% by weight of the finish, based on the Weight of the yarn. Thread breakage occurs after 4.17 minutes of sewing (Singer W1 at 4500 stitches/min).

Example IV A polyester, three-ply test sewing thread, 70 denier per ply, and twisted 22S x 172 for a twist multiplier of 3.7 is constructed of yarn comprising hexalobal filaments, 10 denier per filament, spun from a melt of polyethylene terephthalate. The finish of Example I is applied by the technique of this invention as taught in Example I. After twisting, the thread is heat set at 185 F. The flexural rigidity of the filaments is 10.9 10- gram (centimeter) the coefficient of kinetic friction of the yarn at 550 F. is 0.23, and the coefficient of kinetic friction of the thread at 600 F. is 0.26.

Sewability is determined using a Singer 600 W-1 machine, with a No. 12 needle, operated at 4500 stitches per minute and 12 stitches per inch to sew 4 layers of 9.4 ounces per square yard 56 x 40 cotton duck followed by a Singer 281-1 machine with a No. 12 needle, operated at 5600 stitches per minute and 12 stitches per inch to sew 3 layers of 9.4 ounces per square yard 56 x 40 cotton duck. The median time for thread rupture for these two types of sewing is then determined. For the thread of this example it is observed to be 0.71 minute. When a control thread D is provided identical to the test thread of this example except that the finish does not contain methyl hydrogen siloxane (coefiicient of friction of the yarn being 0.37 at 550 F. and of the thread 0.84 at 600 F.), thread rupture occurs after only 0.04 minute of this test. Control threads E and F are commercial #23/ nylon thread (230 denier), and commercial #23 polyester thread (each being about 2 denier per filament, and twisted of 3 plies, 70 denier per ply), each bearing about 4% of conventional finish. The nylon (E control) thread (with a coefficient of friction of 0.73 at 600 F.) ruptures after 0.09 minute, and the polyester (F control) thread (with a coefficient of friction of 0.88 at 600 F.) ruptures after 0.07 minute.

Example V About 2% by weight based on the weight of the yarn of liquid methyl-phenyl polysiloxane (18,000 cs. viscosity), is applied following the technique of Example IV as a 10% solution of liquid methyl-phenyl. polysiloxane in carbon tetrachloride to the test yarn used in Example IV. The flexural rigidity of the filaments is about ]O.9 l0- gram (centimeter) and the coefiicient of kinetic friction of the thread at 600 F. is 0.35. This thread is used on a Singer 600 W-l single-needle, lockstitch sewing machine operating at 4500 stitches per minute and 12 stitches per inch, with a No. 12 Singer needle to sew 4 layers of 9.4 ounces per square yard, 56 x 40 cotton duck with satisfactory results for over 5 minutes. The thread remains intact, the stitching is uniform, and the layers are firmly sewn together.

The polymer composition of the filaments for this invention are polyamides, polyesters, polyolefins and polyacrylonitrile.

Typical of preferred polyamides are poly(hexamethylene adipamide), poly(methaxylylene adipamide), and polyamides derived from paraxylene a,a-diamine and azelaic acid, and from 4,4-methylene biscyclohexylamide and aliphatic acids such as azelaic, sebacic, and dodecanedioic acids, and their homologs, and copolymers or melt-blends of the above-mentioned polyamides, as well as copolymers with poly(hexamethylene terephthalamide) and with poly(hexamethylene bibenzoamide).

Typical of preferred polyesters are poly(ethylene terephthalate), poly(hexa-hydro p xylylene terephthalate), poly(diphenylol propane isophthalate) poly(bicyclohexyl dimethane bibenzoa-te), and polyesters from naphthalene dicarborylic acids.

Polypropylene is preferred among the polyolefins.

It is apparent that many variations and modifications of this invention may be accomplished without departmg from the spirit and scope of the present invention which is accordingly intended to be limited only by the scope of the appended claims.

What is claimed is:

1. A sewing thread twisted from a continuous filament yarn formed from a linear, synthetic polymer and uni formly bearing on the surface of the said yarn from about 0.9% to about 11% by weight based on the weight of the said yarn of a heat-treated finish selected from the class consisting of (1) a mixture of about 10% by weight aluminum tristearate and by weight dimethyl polysiloxane, (2) methyl phenyl polysiloxane of about 18,000 cs. viscosity and (3) a mixture of methyl hydrogen siloxane and dimethyl siloxane, the filaments of the said yarn having a flexural rigidity of from about 2.7 10 to x10 gram (centimeter) the finish having been applied to the yarn before twisting and having been heat-treated after the yarn bearing the finish has been twisted.

2. The thread of claim 1 wherein item (3) is about 40% by weight methyl hydrogen siloxane and about 60% by weight dimethyl siloxane.

3. The thread of claim 2 wherein the said polymer is a polyamide.

4. The thread of claim 2 wherein the said polymer is a polyester.

5. The thread of claim 2 wherein the said polymer is a polyolefin.

6. A multifilament continuous yam suitable for twisting into thread formed from a linear, synthetic polymer, the filaments of the said yarn having a flexural rigidity of from about 2.7)(10- to 14.0 10- gram (centimeter) and the said yarn having substantially uniformly distributed over its surface from about 0.9% to about 11% by weight, based on the weight of the said yarn, of a finish selected from the class consisting of (1) a mixture of about 10% by weight aluminum tristearate and 90% by weight dimethyl polysiloxane, (2) methyl-phenyl polysiloxane of 18,000 cs. viscosity and (3) a mixture of about 40% by weight methyl hydrogen siloxane and 60% by weight dimethyl siloxane.

7. The yarn of claim 6 wherein the said polymer is a polyarnide.

8. The yarn of claim 6 wherein the said polymer is a polyester.

9. The yarn of claim 6 wherein the said polymer is a polyolefin.

References Cited by the Examiner UNITED STATES PATENTS 2,392,805 1/1946 Biefeld 57153 2,799,598 7/1957 Biefeld et a1 57140 X 2,959,910 11/1960 Woodson 57153 3,081,193 3/1963 Stasse 117138.8 X 10 3,159,600 12/1964 Watkins 117138.8 X

FRANK J. COHEN, Primary Examiner. J. PETRAKES, Assistant Examiner.

Claims (1)

1. A SEWING THREAD TWISTED FROM A CONTINUOUS FILAMENT YARN FORMED FROM A LINEAR, SYNTHETIC POLYMER AND UNIFORMLY BEARING ON THE SURFACE OF THE SAID YARN FROM ABOUT 0.9% TO ABOUT 11% BY WEIGHT BASED ON THE WEIGHT OF THE SAID YARN OF A HEAT-TREATED FINISH SELECTED FROM THE CLASS CONSISTING OF (1) A MIXTURE OF ABOUT 10% BY WEIGHT ALUMINUM TRISTEARATE AND 90% BY WEIGHT DIMETHYL POLYSILOXANE, (2) METHYL PHENYL POLYSILOXANE OF ABOUT 18,000 CS. VISCOSITY AND (3) A MIXTURE OF METHYL HYDROGEN SILOXANE AND DIMETHYL SILOXANE, THE FILAMENTS OF THE SAID YARN HAVING A FLEXURAL RIGIDITY OF FROM ABOUT 2.7X10**-4 TO 14.0X10**-4 GRAM (CENTIMETER)2 THE FINISH HAVING BEEN APPLIED TO THE YARN BEFORE TWISTING AND HAVING BEEN HEAT-TREATED AFTER THE YARN BEARING THE FINISH HAS BEEN TWISTED.