US2477652A - Mixed yarn and fabric - Google Patents

Description

c. ROBBINS, n MIXED YARN AND FABRIC 2 Sheets-Sheet l (arm/v carro/v INVENTOR.

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MIXED YARN AND FABRIC 2 Sheets-Sheet 2 Filed March 1, 1946 Patented Aug. 2, 1949 UNITED STATES PATENT OFFICE MIXED YARN AND FABRIC Chandler Robbins, II, Auburn, Maine Application March 1, 1946, Serial No. 651,406

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 9 Claims.

The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a base fabric for coating, and more particularly to a base fabric comprising a mixture of high-tenacity fibers having relatively poor adhesion to a natural or artificial resin or rubber coating and of lower-tenacity fibers having relatively strong adhesion to such coating.

The use of highly polymerized synthetic fibers, such as nylon, rapidly increases in the textile art because of their numerous advantages among which are strength, elongatability, and attractive appearance. However, it has been found heretofore that it was not feasible to coat these fibers with conventional natural or synthetic resin or rubber coatings in such a manner as to secure a strong bond between the base fabric and the coating; on the contrary, the experience of the art has been that a coating applied to a nylon fabric will peel off after a comparatively short period of wear. As a consequence, the durability of nylon and other highly polymerized synthetic fabrics as used in the manufacture of waterproof clothing has never been fully satisfactory; although the synthetic threads are waterproof, water will leak through the interstices between the threads in the fabric after the coating has worn off. Synthetic fabrics coated on one side only have shown particularly bad wearing characteristics.

An object of the present invention therefore is a base fabric for the application of coating, which combines the advantages of the strength, elongatability and appearance of highly polymerized synthetic fibers, with good adhesion to coating which heretofore has been lacking in fibers of this type.

Another object of the present invention is a mixed fabric suitable for the application of a coating thereto, which is made of a yarn composed of high-tenacity threads having poor adhesion to the coating and of lower-tenacity threads having good adhesion to coating.

A further object of this invention is a base fabric for the application of a coating, which combines great strength, light weight, and strong adhesion to the coating.

Yet another object of the invention is a mixed yarn composed of threads differing in tenacity, elongation and adhesion to coating characteristics, and a method of combining them in such a manner that the ultimate elongation of the two materials is equal at the breaking point of the composite yarn.

And another object of the present invention is clothing and covering made of highly polymerized synthetic threads, permanently waterproofed, fireproofed, mothproofed, or mildew proofed by a coating strongly adhering to the completed fabric.

Another object of the invention is a fabric comprising highly polymerized synthetic threads, which is coated only on one side with a firmly adhering coat.

The foregoing and other objects of the present invention are accompanied by combining (1) a highly polymerized synthetic thread, such as nylon, which has great strength and elongatability, while, however, being substantially inelastic as compared with rubber threads, but poor adhesion to coating and (2) a thread of lower tenacity and elongatability but good adhesion to coating, e. g., cotton, into a composite yarn by twisting the less elongatable thread around the more elongatable thread in a spiral unbonded to the latter thread, making a fabric from the composite yarn, and applying a coat or a number of coats to the fabric.

The appended drawings illustrate a composite yarn, suitable for making a base fabric for coating in accordance with the present invention.

Fig. 1 shows a two-component composite yarn in the untensioned state, and

Fig. 2 shows the same yarn in the tensioned state.

Figure 3 shows a three-component yarn in the untensioned state.

Figure 4 shows the three-component yarn of Figure 3, but in the tensioned state.

Figure 5 is a plan view of a coated fabric; and

Figure 6 is an enlarged section through the fabric of Figure 5 along lines 6--6, showing crossed composite filling and warp threads coated on one side, in accordance with the present invention.

Reference numeral H in the drawings denotes It is believed that the cause of poor adhesion of coating to highly polymerized synthetic fabrics, such as highly polymerized linear polyamides (nylon), is the smooth surface thereof which prevents a strong bond between fabric and coating. On the other hand, most natural and some artiflcial fibers show under the microscopic a scaly or corrugated surface, and yarns spun with relatively short natural fibers have on their surface short ends of scaly or corrugated fibers to which applied coating may become bonded, and their strong adhesion to coating is thought to be due to these properties.

A fabric composed of highly polymerized synthetic smooth threads and other threads with a scaly surface possesses merit in having much better adhesion characteristics than a fabric consisting solely of highly polymerized synthetic threads. In a base fabric consisting exclusively of highly polymerized synthetic fabrics, such as nylon, the adhesion of the coating to the fabric is not due to adhesion of the coating to the threads, but to adhesion of the coat of one side of the fabric to the coat on the other side of the fabric through the interstices between the threads. Such adhesion is obviously poor and the coating will quickly peel off; when the base fabric is flexed or creased, the bond between the two layers .of coating will crack, which leads to quick deterioration of the coating. Where, however, as in the proposed mixed fabric, the coating adheres to the threads themselves, the coating will fiex with the fabric and thus permanently adhere to its base.

In order to obtain a base fabric suitable for the application of coating, wherein not only a strong bond exists between the base and the coating, but where the elongatability and strength of the yarn composing the fabric bears the most favorable relation to its weight, it has been found that such a yarn can be obtained by combining a high strength material such as nylon yarn with a, yarn such as cotton, by either a twisting or spinning process to form a composite yarn of nylon and cotton. This may be carried out on conventional twisting and spinning machinery used either in the silk throwing or cotton twisting industries. The yarn thus formed is then woven into a fabric which, when coated by conventional methods, such as calenderizing or spread coating, forms a waterproof fabric for the manufacture of suchitems as raincoats, ponchos, boots, coverings, compactly folding lifeboats, etc. These fabrics have high strength in relation to weight, as compared with conventional base fabric, such as cotton or rayon. The coat applied to the mixed fabric will have an adhesion thereto several times greater than that of a coating film to fabrics composed solely of nylon or other smooth threads to which the coating films do not adhere to any appreciable degree, and which can be quickly rubbed ofl from the base. A coat applied to the mixed fabric will firmly adhere thereto, even if it is applied to only one side of the mixed fabric.

It has further been found that the mixed fabric can be made in such a manner that it retains the high'strength and elongatability of the synthetic material, if the yarn composing the fabric is made in the following manner. A cotton yarn having a relatively high number of turns per inch, is twisted around a nylon yarn, preferably in a direction opposite from that in which the cotton yarn was originally spun. The cotton yarn thus forms a loose spiral around the nylon yarn. When the composite yarn is placed under stress, a considerabie amountof strain must then occur before the cotton fibers become taut. For example, a high tenacity nylon yarn requires approximately 20% elongation before it breaks, while cotton yarn breaks after an elongation of only approximately 10%. It is thus possible to form a composite yarn, consisting of a spiral in which the nylon may be stretched 10% before the cotton becomes taut; and upon reaching the ultimate elongation point (20%) of the nylon, both the cotton and the nylon will break at the same time. The full tenacity of both the cotton and the nylon is thus utilized in resisting strains up to the breaking point. By winding the cotton yarn around the nylon yarn in a direction opposite to the one in which the cotton yarn was originally twisted, the threads composing the cotton yarn are partly untwisted, which enlarges the surface of cotton material to which the coatin may adhere.

The following examples illustrate a particular instance of an actual application of the present invention, but do not constitute a limitation of the invention to the specific materials and figures set forth in the examples:

Example I A fine cotton yarn of 10 yards in length and having elongation capacity of 10%, containing 32 turns per inch, is placed adjacent to a strand of untwisted nylon of 10 yards length, the nylon having an elongation capacity of 20%. The two textiles are then twisted in a direction opposite to the direction of the twist originally in the cotton yarn. This action causes a reduction in the helix angle of the fibers in the cotton yarn and an increase, therefore, in the total length of. the cotton yarn which distributes itself along the length of the nylon yarn. If, for example, the combination yarn is turned 19 turns per inch, the result gained in the length of the cotton yarn may be approximately 8%, whereas the increase in the helix angle of the fibers in the nylon yarn may shorten the nylon approximately 2%, thus making an over-all diiferential of 10% between the two components in the yarn. The composite yarn is placed in a testin machine and elongated to a length of 11 yards; the nylon component of the yarn is now under stress, while the cotton spiral is taut but unstressed. Upon further elongation to a length of 12 yards, the point of ultimate elongation of the nylon component and of the cotton component is reached, and any elongation beyond 12 yards will result in breakage of the composite yarn.

Example II A composite nylon and cotton yarn made in the manner and proportions set forth in Example I is woven into a fabric, and a polyvinyl chloride film is applied to the fabric by calenderizing or spread coating. The resulting coated fabric has substantially the same strength as the sum of the strength of a pure nylon fabric, containing an amount of nylon equal to that contained in the combined fabric, plus the strength of a cotton fabric, manufactured with an amount of cotton equal to the amount of cotton used in the combined fabric; and has an elongatability substantially the same as a pure nylon fabric and has substantially the same good adhesion of the coating as a pure cotton fabric.

While the foregoing examples particularly mention nylon, a highly polymerized synthetic. linear polyamide, it must be understood that other synthetic fabrics, such as vinyl yarns, may be employed instead of nylon. Other yarns suitable in place oi nylon are high-tenacity rayon and other high-tenacity regenerated cellulose fibers.

Similarly, while cotton has been mentioned as an example of a comparatively low strength and low elongatability textile which, however, possesses good adhesion to coating, other textiles, such as wool, linen, sisal, hemp, flax, and jute may take its place. Silk also may be used in lieu of cotton, provided that the textile with which it is combined has a tenacity and elongatability exceeding that of silk; nylon is a textile which excels over silk in these properties. A mixed fabric of rayon and of another textile exceeding rayon in tenacity and elongatability is also within the scope of the present invention.

Examples of coatings suitable for application to a mixed fabric in accordance with the present invention, in addition to polyvinyl chloride, are cellulose nitrate, linseed oil, neoprene, butyl rubber, butadiene polymer synthetic rubber, natural rubber, and, in fact, all other coatings for fabrics that are now known to the art.

The lengths of the component textiles in the composite spiral illustrated in Fig. 1 are functions of the helix angles of the yarns which make up the. spiral. The helix angle of a strand of untwisted parallel filaments is and the helix angle approaches 90 the more tightly twisted the yarn is; if parallel filaments are twisted to form a yarn, the length of the twisted yarn is obviously less than that of the parallel filaments prior to twisting and the length of the yarn decreases with each additional twisting turn. 0n the other hand, if a highly twisted yarn is partly untwisted, its helix angle decreases, while its length increases. By twisting together an untwisted strand (or a low-twist yarn) and a comparatively highly twisted yarn in a direction opposite to the direction of the twist of the latter yarn, the length of the former is caused to decrease because it becomes more tightly twisted with every additional turn, and the length of the latter is caused to increase, inasmuch as each additional turn in a direction opposite to the direction of the original twist of the latter yarn progressively untwists it. The number of turns necessary for increasing the length of a highly twisted yarn to a predetermined length by partly untwisting it varies with the diameter of the filaments composing the yarn, and can be determined by simple experimentation (such as counting the number of turns necessary for increasing the length of a -yard sample of highly twisted cotton yarn to 11 yards).

The length to which each component textile which goes into the composite spiral is to be adjusted is calculated in the following manner:

The length of the more elongatable component ii of the spiral equals the length of the spiral itself; and the length of the less elongatable component l2 equals that of an untensioned strand of the less elongatable component which, when stretched to the breaking point, will correspond to the length of the more elongatable component at the point of ultimate elongation of the latter. Thus, in the foregoing Example I, the 10 yards of high tenacity nylon will have a length of 12 yards at the point of ultimate elongation the length of a strand of cotton (10% elongation) which will break at 12 yards is about 11 yards (exactly l0 11 yards); consequently 10 yards of untensioned composite yarn will contain cotton yarn wound in a loose spiral around nylon in a ratio of 11 to 10, that is, 11 yards of cotton yarn around 10 yards of nylon. If instead of nylon another synthetic textile having only. 15% elongation capacity is chosen, the ratio is 10.5 (cotton) to 10 (synthetic textile) inasmuch as a 10-yard strand of a synthetic textile with'15% elongation capacity will break when stretched to 11 /2 yards. and the length of a cotton strand (10% elongation capacity) which breaks when stretched to the same length of 11 yards is about 10 yards (exactly 10 /11 yards). Conversely, if the composite yarn consists of nylon (20% elongation capacity) and a grade of silk having only 15% elongation capacity, but a better adhesion to coating than nylon, the ratio between nylon and silk in the spiral will be 10 to approximately 10.5 (more exactly, 10.435) the latter figure is computed by ascertaining the length of an untensioned strand of silk which, when stretched 15%, will break at an ultimate elongation to 12 yards (correspondin to the ultimate elongation of a 10-yard strand of nylon).

The length of the untensioned less elongatable material always exceeds that of the untensioned more elongatable material, inasmuch as the former is wound in a loose spiral around the latter.

A composite yarn in accordance with the present invention may also consist of three or more different materials, differing in strength, elasticity, and adhesion to coating, or in any one or two of those properties. The lengths of materials needed to make a composite yarn which will break at the point orultimate elongation of the component having the greatest elongatability, are computed in the same manner as is the case of a composite yarn composed of only two difierent materials; thus in the case of a composite 10 yard yarn of cotton- I2 (10% elongation capacity), silk I3 (15% elongation capacity) and nylon ll (20% elongation capacity), the ratio is 11 to 10.5 to 10; that is, in a 10 yard composite spiral, an 11 yard helix of partly untwisted cotton yarn and a 10 /2 yard helix of partly untwisted silk yarn are wound in a loose spiral around a 10 yard core of nylon.

As in the case of a composite yarn comprising two diflerent materials, best coating results are obtained in a yarn composed of three or more different yarns, if the yarns having relatively lesser elongatability but good adherence to coatin are wound around the more elongatable, but smooth and poorly coat-adhering material in a direction opposite to the direction in which the less elongatable yarns were originally twisted.

It is to be understood that the examples and specific figures given in the foregoing description are only for purposes of illustration and are not to be deemed to constitute a limitation of the scope of the invention. It is obvious that substitutions of equivalent materials with characteristics suitable for attaining the objects of the invention will readily occur to the expert; and such substitutions are within the spirit and scope of this invention. I desire to claim my invention broadly and to be limited only by the appended claims.

I claim:

1. For use in a coated fabric, a composite yarn of great breaking strength and having good ad esion to coating, comprising a highly polymerized synthetic thread and a twisted natural textile yarn forming an unbonded spiral around the same, saidnatural textile yarn having a rougher surface and lesser elongatability than said synthetic thread, the length of the filaments of said twisted natural textile yarn in the untensioned state being greater than the length or said synthetic thread by an amount substantially equaling 7 the difference between the amounts by which said natural filaments and said synthetic material are respectively elongatable prior to. breaking, said synthetic and natural materials being of substantially the same length at their point of ultimate elongation.

2. For use in a coated fabric, a composite yarn having great breaking strength and good adhesion to coating, comprising nylon thread and a twisted cotton yarn having a rougher surface than said nylon and forming an unbonded spiral around said nylon, the length of said cotton yarn diflering in the untensioned state from the length of said nylon in the untensioned state by an amount substantially equaling the difference between the amounts by which said nylon and said cotton are respectively elongatable prior to breaking, and said nylon and cotton being of substantially the same length at their point of ultimate elongation.

3. A textile base for a coating, said textile base having great breaking strength and good adhesion to coating and comprising a substantially inelastic composite yarn, said composite yarn comprising a smooth-surface textile material core and a yarn comprising textile material less elongatable than and having better adhesion to coating than said first-named textile material and forming an unbonded spiral around said first-named textile material, said core and said last-named yarn being of substantially equal length at their point of ultimate elongation, and the length of the filaments of said last-named yarn differing in the untensioned state from the length of said core by an amount substantially equal to the diiference between the amounts by which said textile materials are respectively elongatable prior to breaking.

4. A coated textile fabric comprising a textile base and a coating on said textile base, said textile base comprising substantially inelastic composite yarn of great breaking strength and having good adhesion to coating, said composite yarn comprising a smooth-surface textile material core and a yarn comprising textile material less elongatable than and having better adhesion to coating than said first-named textile material and forming an unbonded spiral around said firstnamed textile material, said core and said lastnamed yarn being of substantially equal length at their point of ultimate elongation, and the length of the filaments of said last-named yarn differing in the untensioned state from the length of said core by an amount substantially equal to the difference between the amounts by which said textile materials are respectively elongatable prior to breaking.

5. A coated textile fabric comprising a textile base and a coating on said textile base, said textile base comprising composite yarn of great breaking strength and having good adhesion to coating, said composite yarn comprising a highly polymerized synthetic thread and a twisted natural textile yarn forming an unbonded spiral around the same, said natural textile yarn having a rougher surface and lesser elongatability than said synthetic thread, the length of the filaments of said twisted natural yarn in the untensioned state being greater than the length of said synthetic thread by an amount substantially equaling the diiference between the. amounts by which said natural filaments and said synthetic material are respectively elongatable prior to breaking, said synthetic and natural materials being of substantially-the same length at their point of ultimate elongation.

8. A coated textile fabric comprising a textile base and a coating on said textile base, said textile base comprising composite yarn of great breaking strength and having good adhesion to coating, said composite yarn comprising nylon thread and a twisted cotton yam having a rougher surface than said nylon and forming an unbonded spiral around said nylon, the length of said cotton yarn differing in the untensioned state from the length of said nylon in the untensioned state by an amount substantially equaling the diilerence btween the amounts by which said nylon and said cotton are respectively elongatable prior to breaking, and said nylon and cotton being of substantially the same length at their point of ultimate elongation.

'7. A coated fabric comprising: a textile base of great breaking strength and good adhesion to coating, said textile base comprising substantially inelastic composite yarn, said composite yarn comprising a smooth-surface textile material core and a yarn comprising textile material less elongatable than and having better adhesion to coating than said first-named textile material and forming an unbonded spiral around said firstnamed textile material, said core and said lastnamed yarn being of substantially equal length at their point of ultimate elongation, and the length of the filaments of said last-named yarn differing in the untensioned state from the length of said core by an amount substantially equal to of said twisted natural the difference between the amounts by which'said textile materials are respectively elongatable prior to breaking; and a coating on only one side of said fabric.

8. A coated fabric comprising a textile base of great breaking strength and good adhesion to coating, said textile base comprising composite yarn, said composite yarn comprising a highly polymerized synthetic thread and a twisted natural textile yarn forming an unbonded spiral around the same, said natural textile yam having a rougher surface and lesser elongatability than said synthetic thread, the length of the filaments textile yarn in the untensioned state being greater than the length of said synthetic thread by an amount substantially equaling the difference between the amounts by which said natural filaments and said synthetic material are respectively elongatable prior to breaking, said synthetic and natural materials being of substantially the same length at their point of ultimate elongation; and a coating on only one side of said fabric.

9. A coated fabric comprising a textile base of great breaking strength and good adhesion to coating, said textile base comprising composite yarn, said composite yarn comprising nylon thread and a twisted cotton yarn having a rougher surface than said nylon and forming an unbonded spiral around said nylon, the length of said cotton yarn difiering in the untensioned state from the length of said nylon in the untensioned state by an amount substantially equaling the difference between the amounts by which said nylon and said cotton are respectively elongatable prior to breaking, and said nylon and cotton being of substantially the same length at their point of ultimate elongation; and a coating on only one side of said fabric.

CHANDLER ROBBINS, 11.

(References on following page) REFERENCES CITED The following references are of record In the file of this patent:

Number UNITED STATES PATENTS Name Date Metcalf Jan. 9, 1906 Jen-ems June 30, 1908 Farrell Feb. 7, 1928 Brewster Feb. 21, 1928 Rochester Oct. 17, 1933 A1168 Sept. 1, 1936 Number 10 Number

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