CA1295490C - Insulating fabric and method of manufacture thereof - Google Patents
Insulating fabric and method of manufacture thereofInfo
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- CA1295490C CA1295490C CA000541086A CA541086A CA1295490C CA 1295490 C CA1295490 C CA 1295490C CA 000541086 A CA000541086 A CA 000541086A CA 541086 A CA541086 A CA 541086A CA 1295490 C CA1295490 C CA 1295490C
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- knitted
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Abstract
INSULATING FABRIC AND METHOD OF MANUFACTURE THEREOF
Abstract of the Disclosure Insulating fabric having a knitted base fabric incorporating air-entrapping cells on one or both sides. The base fabric is knit from a bulk yarn, preferably high bulk acrylic yarn, and a combination polyester and cotton yarn, the yarns being knitted separately in selected fabric courses. The inner face of the fabric is formed of the bulk acrylic yarn, to provide a soft, warm and comfortable interior surface when worn. The outer face of the fabric is formed of the polyester/cotton yarn, which provides a knitted framework for anchoring and stabilizing the bulk yarn in the fabric. Following knitting, the fabric is subjected to a series of finishing operations which include scouring, padding, drying and calendering.
Preferably, the inner acrylic surface of the fabric is napped prior to calendering. As the result of repeated washings, the insulating fabric of the invention increases in thickness to enhance its heat insulating capability and provide increased warmth.
Abstract of the Disclosure Insulating fabric having a knitted base fabric incorporating air-entrapping cells on one or both sides. The base fabric is knit from a bulk yarn, preferably high bulk acrylic yarn, and a combination polyester and cotton yarn, the yarns being knitted separately in selected fabric courses. The inner face of the fabric is formed of the bulk acrylic yarn, to provide a soft, warm and comfortable interior surface when worn. The outer face of the fabric is formed of the polyester/cotton yarn, which provides a knitted framework for anchoring and stabilizing the bulk yarn in the fabric. Following knitting, the fabric is subjected to a series of finishing operations which include scouring, padding, drying and calendering.
Preferably, the inner acrylic surface of the fabric is napped prior to calendering. As the result of repeated washings, the insulating fabric of the invention increases in thickness to enhance its heat insulating capability and provide increased warmth.
Description
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INSULATING FABRIC AND METHOD OF MANUFACTURE THEREOF
Background of the Invention This invention pertains to fabrics designed and intended primarily for use in winter weight underwear.
I~owever, since the fabrics of the invention have an insulating quality, their use is not limited to winter underwear garments. They have utility wherever fabric warmth i~ desired, for example, in the manufacture of sweaters, sportswear, blankets and the like.
From time immemorial it was conventional for winter underwear fabrics to be sold by weight, for the reason that, in general, the heavier the fabric the warmer the garments made from it. The reason for this iB that textile fibers entrap air to a substantial degree, and it is the entrapped air which gives a fabric its insulating quality. Thus~ the insulating or thermal effectiveness of a fabric u~ed in making cold weather garments, such a~ winter underwear, i~
;determined by the amount of air entrapped in the fabric. Accordingly, in the days of yore, winter wear - 20 fabrics were designed on the theory that the heavier the fabric by weight, the warmer it would be.
In more recent years, however, fabric designers have developed new fabrics constructed with air-entrapping cells or pockets on one or both sides which provide dead air spaces in the fabric. Such fabric structures trap more air than that entrapped by the fibers alone, and thus enhance the insulating quality of the fabric. Knitted fabrics constructed with a multitude of such air pockets or air-entrapping cells are known as "thermal" fabrics.
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3L295~90 The air-entrapping cells in such fabrics are three dimensional cavities having spaced top, bottom and side walls and a floor, which trap and retain air warmed by the heat of the human body. The trapped air gives the fabric an enhanced heat insulating or heat retention quality, thus adding to it insulation, warmth or "thermal" quality.
The original thermal fabric, first known as "waffle knit" fabric, was developed by the United States Navy for military u~e in about 1951. The Navy's waffle knit fabric is a flat, warp knit fabric made on a double needle bar raschel knitting machine. It soon found acceptance for civilian use in underwear, and became known popularly as "thermal underwear". A brief history of the Navy IB waffle knit raschel thermal fabric will be found in Professor William E. Schinn's article "The Philip Model PT/RR Machine" published in the April 1968 issue of "'rhe Knitter" magazine, beginning at page 37.
A great interest soon arose in the underwear industry for developing a competing weft knit thermal fabric which could be made on conventional circular knitting machines. A weft knit thermal fabric eventually was developed, for which Morgan United 25 States Patent No. 2,839,909 was granted. The Morgan patented fabric is made on a multifeed circular rib knitting machine having dial and cylinder needles disposed in a 2 x 2 rib knitting arrangement. Its air-entrapping cells are produced by alternate triple tucking, first on one ~et of needles, then on the other set of needles, the non-tucking needles knitting plain stitche~. The Morgan thermal fabric is characterized by spaced groups of tuck strands extending across the ~, .. .. . .
`` 12~35490 valleys formed between the ribs of the fabric, the ribs forming the ~ide walls of the air-entrapping cells and the spaced tuck strands forming the top and bottom walls of the cells.
Later on, a second weft knit thermal fabric was developed utilizing the Philip Model PT/RR knitting machine, for which Philip United States Patent No.
3,568,475 was granted. The PT/RR machine is a multifeed 1 x 1 circular rib knitting machine using the flexer principle to rack the dial needles. In knitting the Philip patented fabric, the machine is arranged for knitting a full cardigan fabric. Selective racking of the dial needles is utilized, whereby the needles assume a 2 x 2 rib relation~hip during knitting of the fabric. Because the air-entrapping cells in succeeding rows in the Philip thermal fabric are staggered, the fabric more nearly 3imulates the raschel thermal fabric in appearance than does the earlier Morgan thermal fabric.
Subsequently, a third weft knit thermal fabric was introduced by J.E. Morgan Knitting Mills, Inc. of i Tamaqua, Pennsylvania which simulates yet more closely in appearance the raschel knit thermal fabric. This fabric is known in the trade as "circular raschel"
because of its close simulation to the raschel thermal fabric. It is composed of repetitive sequences of knit, tuck and welt stitches which produce multiple air-entrapping cells disposed in staggered relationship on both sides of the fabric. The circular raschel thermal fabric also is knitted on a 1 x 1 circular rib knitting machine. Needle selection means are operative to select needles in alternating and repetitive sequences for knitting, tucking and welting in ~' :, , ~295490 recurring cycles to produce a weft knit thermal fabric incorporating air-entrapping cells constructed of knitted stitches, tuck loops and floats.
For many years winter wear garments made from the raschel, Morgan, Philip and circular raschel thermal fabrics have been sold in the United States. The manufacture and sale of such thermal garments still is taking place.
In the knitting of fabrics generally, it is old practice to knit two or more yarns into a fabric in such a manner that one of the yarns appears on one face of the fabric and a different yarn appears on the opposite face of the fabric. In weft knitting, "plating" is a common practice in hosiery manufacture, wherein fabric is knitted of two yarns which may differ in color or other characteristic. The plated fabric is knit ~o that one yarn is visible on one side thereof and the other yarn is visible on the opposite side.
Morancy U.S. Patent No. 2,946,210 discloses a rib knit fabric formed of inelastic, elastic and stretch yarns and knitted so that the stretch yarn appears on the inner side of the fabric to provide a relatively soft texture, while the inelastic yarn i~ disposed on the outer face of the fabric to provide a relatively stiff and smooth texture.
Napping is a decades-old practice in which a small portion of the yarns on one or both sides of a knitted or woven fabric are raised mechanically to provide a fibrous surface. Usually, napping is carried out by causing the fabric to pass over a rotatable cylinder having teeth or spikes on its periphery which pick up the surface fibers of the yarns to a slight extent without tearing or otherwise damaging the fabric.
~295490 ;~organ U.S. Patent 2,839,909 aforesaid discloses the napping of a knitted thermal fabric.
Summary of the Invention The insulating fabric of this invention is characterized by a knitted base fabric having air-entrapping cells. The fabric preferably is knit from a bulk or high bulk acrylic yarn and a combination polyester and cotton yarn. The yarns are fed to the knitting machine needles separately at selected yarn feeds. The inner face of the fabric is formed of the acrylic yarn. The outer face of the fabric is formed of the combined polyester and cotton yarn. The polyester/cotton yarn provides an exterior knitted framework for anchoring and stabilizing the acrylic yarn in the fabric. The inner fabric surface formed of the acrylic yarn provide3 a soft texture and a warm, comfortable feel or hand when the fabric i~ worn next to the ~kin, as in the ca~e of thermal underwear.
The primary object of this invention is to provide a new and improved knitted insulating fabric for use in the manufacture of winter wearing apparel, such as underwear, which is warmer, lighter in weight, more comfortable in wear and more resistant to shrinking than knitted fabrics heretofore made and ~old, and which is characterized by an ability, as the result of -; several machine washings, to increase both in thickness and warmth by at least 25%.
A further object of the invention is to provide a new and improved knitted insulating fabric having a bulk yarn knit in selected courses in the fabric, the ~; bulk yarn being disposed on one surface of the fabric and being anchored and stabilized therein by a knitted framework composed of a combined ~ynthetic/cotton yarn.
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In a preferred arrangement, a high bulk yarn is knit in alternating courses of the fabric and the combined synthetic/cotton yarn is knit in the intervening courses of the fabric.
A further object is to provide a new and improved insulating fabric having a base fabric constituted of knitted thermal fabric having air-entrapping cells, the fabric being knit of high bulk acrylic and blended polyester/cotton yarns disposed separately in selected courses, the fabric being characterized by stability, light weight with increased warmth, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and an inherent capacity, upon repeated washings, to increase substantially in bulk, thickness and warmth.
Yet a further object of the invention i~ to provide a new and improved lightweight insulating fabric having a ba~e fabric incorporating air-entrapping cells, the fabric being knit of medium weight acrylic bulk yarn and medium weight blended polyester/cotton yarn disposed separately in selected courses. The fabric is characterized by stability, increased warmth despite its relatively light weight, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and an inherent capacity, upon repeated washings, to increase substantially in bulk, thickness and warmth.
A further object is to provide a method of knitting new and improved insulating fabrics which permits bulk yarns, particularly high bulk acrylic yarn, to be knit succe~sfully into the fabric and to be stabilized and retained therein during subsequent textile finishing operations, including napping, and during repeated wear and laundering.
~29~490 Other objects and advantages of this invention will be readily apparent from the following description of preferred embodiments thereof, reference being had to the accompanying drawing.
Description of the Views of the Drawing Fig. l is an enlarged, fragmentary view illustrating schematically a preferred weft knit thermal fabric utilized in the practice of this invention.
Fig. 2 is a knitting diagram showing schematically the operation of the cylinder and dial needles in knitting successive courses of the thermal fabric illustrated in Fig. l of a l x l circular rib knitting machine.
Fig. 3 is a schematic view of flow-sheet character illustrating the preferred sequence of manufacturing steps utilized in making an insulating fabric embodying this invention.
Fig. 4 is a graph depicting the characteristic of the insulating fabric of the invention of first increasing and then stabilizing in thickness a~ a result of repeated washings, thereby adding bulk and warmth to the fabric.
Fig. 5 is an unmagnified photograph showing the inner faces of two identical swatches of an insulating fabric incorporating this invention, the fabric on the left being unwashed and that on the right having been washed ten times.
Fig. 6 is a photograph magnified thirty times, showing in side elevation the relative thickness of the two fabrics illustrated in Fig. 5, the upper fabric ;~ being the unwashed fabric and the lower fabric being : the fabric which had been washed ten times.
. . .
129~;490 Fig. 7 is a second knitting diagram showing schematically the operation of the cylinder and dial needles in knitting an alternative weft knit thermal fabric utilized in the practice of this invention.
Fig. 8 is a third knitting diagram showing schematically the operation of the cylinder and dial needles in knitting a modified insulating fabric in accordance with this invention.
Detailed Description of the Invention The insulating fabric of this invention may be incorporated into any known knitted thermal fabric having air-entrapping cell~ formed on one or both sides of the fabric. For more effective insulation, however, it i~ preferred that the air-entrapping cells be formed on both sides.
Figure~ 1-6 of the drawing depict the ernbodiment of the invention which utilizes as the ba~e fabric the circular raschel type of thermal fabric having air-entrapping cells on both ~ides constructed of a combination of knitted stitches, tuck loops and floats concatenated in a selected sequence.
Referring first to Fig. 1, where a portion of a circular ra~chel thermal fabric 10 is shown schematically, there are illustrated successive course-wi~e extending rows 11, 12, 13, 14, 15 of plural air-entrapping cells 17. The cells 17 are defined by course-wise spaced side walls 19, 20 and wale-wise spaced top wall~ 21 and bottom walls 22. Each cell i~
provided with a floor 23 disposed intermediate the ~paced side, top and bottom walls.
Tha base fabric 10 depicted in Fig. 1 i~ a 1 x 1 rib knitted fabric made on a multi-feed weft knitting machine having opposed needle bank~. Preferably, the 12~S4~1~
g needles are independently mounted in each of the needle banks with capacity to be raised and lowered selectively to clear level, tuck level, welt level and cast-off level, utilizing well known and conventional needle ~electing means, to produce rib knitted fabric incorporating the stitchei, tuck loops and floats which form the air-entrapping cells 17 in the fabric.
A suitable knitting machine for producing the thermal fabric 10 depicted in Fig. 1 is the Albi ROFS
16 feed, coarse gauge, body size, circular rib knitting machine. The Albi machine is provided with a rotatable cylinder and dial, each incorporating a plurality of independent needle~ alternating in a 1 x 1 arrangement.
Positive yarn feeding means are utilized, such as furnishing wheels, to feed yarn to the needle~ at each of the yarn feeds at a selected rate of feed. A 10 cut machine is preferred, having a needle cylinder diameter within the range of 12" to 17" for knitting body size tubular fabric. The machine preferably is operated to knit a 16 feed, 8 repeat stitching cycle, shifting the knitting pattern after 4 repeat~ to provide the in-and-out effect necessary to form the air-entrapping cells 17 in staggered relation throughout the fabric.
To ensure a tight knit fabric, the yarn i9 fed to the needles under a relatively heavy tension, a~ is usual in knitting thermal fabrics.
Fig. 2 illu~trates the preferred method for knitting the thermal fabric 10 on a 16 feed circular rib knitting machine. The vertical columns denoted C
and D refer to individual needles mounted on the cylinder and on the dial, respectively. The horizontal row~q numbered 1, 2, 3, etc. to 16 identify consecutive yarn feeds spaced at uniform interval~ around the ~, , ~295~
needle cylinder of the machine. The letters T, K and W
indicate, respectively, whether the cylinder and dial needles tuck, knit or welt during the knitting process.
The knitting diagram constituting Fig. 2 of the drawing depicts the stitch structure of the fabric 10 as well as the method of knitting that fabric. In illustrating the fabric, the horizontal row of letters C, D, C, etc. depicts, in alternation, the cylinder needle wales and the dial needle wales of the fabric.
The vertical left-hand column of numbers 1, 2, 3, etc.
indicates the courses of the fabric. The letter K
identifies a knitted stitch, and the letter T indicates a tuck loop. The letter W indicates where a float is formed in the fabric when a needle is retained at welt level.
Fig. 2 depict~ one complete knitting cycle of the ba~e fabric 10 constituted of 16 yarn feed~/courses which produce, in the fabric, two successive course-wise extending row~ 11-15 of air-entrapping cells 17, the cells of adjacent rows being staggered relative to each other.
As the knitting diagram of Fig. 2 illustrates, during knitting of the first 8 courses of a fabric cycle, all of the dial needles produce knitted stitches at the alternate yarn feeds 1, 3, 5 and 7. At those feeds the alternate cylinder needles are lowered to welt level to produce floats in the fabric, while the intervening cylinder needles are tucked to produce tuck loops. Meanwhile, at the intervening yarn feeds, 2, 4 6 and 8 the cylinder needles produce knitted stitche~, alternate dial needles produce tuck loop~ and the intervening dial needles are welted to produce yarn floats.
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During the knitting of the second 8 courses of the fabric cycle, at yarn feeds 9 to 16 inclusive, the knitting sequence is shifted to provide the in-and-out effect which creates the staggered air-entrapping cells 17 in successive rows 11-15 of the fabric 10. At the alternate yarn feeds 9, 11, 13 and 15, all dial needles continue to produce knitted stitches, but the cylinder needles are operated in reverse sequence. Alternate cylinder needles are tucked to produce tuck loops, while the intervening cylinder needles are welted to produce yarn floats. At the intervening yarn feeds 10, 12, 14 and 16, the cylinder needles continue to form knitted stitches, but the dial needles operate in reverse sequence, with the alternate dial needles welting to produce yarn floats and the intervening dial needles producing tuck loop~.
The cycle of knitting depicted in Fig. 2 i~
repeated ~ucce~ively during the knitting of the fabric 10 to provide a fabric incorporating on each side a plurality of course-wise extending row~ of air-entrapping cells 17, exemplified by rows 11-15, with the individual cells 17 of each row staggered relative to the cell~ of its adjacent rows.
In knitting the insulating fabric depicted in Figs. 1-6, high bulk 100% acrylic yarn i9 fed to the needles at the alternate yarn feeds 1, 3, 5, 7, 9, 11, 13, 15 while a blended polyester and cotton yarn is fed to the needles at the intervening yarn feeds, 2, 4, 6, 8, 10, 12, 14i 16. As a reqult, the acrylic yarn appears on the inside face of the fabric and the combined polyester and cotton yarn appears on the out3ide face of the fabric.
....
12954~
Becau~e of its low moisture absorbency, ability to dry quickly, warmth characteristics, high bulk to weight ratio and soft, pleasant and resilient hand, the desirability of using high bulk acrylic yarn for knitting winter weight underwear long has been recognized. But high bulk acrylic yarn does not readily lend itself to the satisfactory knitting of fabrics. Because of the bulked character of such yarn, the resulting fabric is unstable, and is subject to ballooning, particularly width-wise, as a result of repeated launderings. Even during the knitting process, while still on the machine, the newly knitted fabric tends to balloon. For that reason, high bulk acrylic yarn has not been found to be satisfactory for knitting underwear fabrics.
The invention provide~ a solution to the in~tability problem inherent in the knitting of high bulk acrylic yarn. Knitting such yarn in combination with a blended polyester and cotton yarn introduces into the fabric the stability necessary to enable the knitting of commercially acceptable underwear fabrics from high bulk acrylic yarn. The problem of the ballooning of the fabric, both during the knitting process and as the result of subsequent laundering, i9 eliminated. And the finished fabric incorporates sufficient rigidity to maintain fabric stability during all of the po~t-knitting processes, such a~ scouring, drying, calendering, cutting and sewing, and during subsequent garment wear and laundering. In the fini~hed fabric, the polyester/cotton yarn, which appears on the outside of the fabric, provides a relatively rigid knitted framework for anchoring and stabilizing the high bulk acrylic yarn which forms the inner face of the fabric.
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A highly satisfactory insulating fabric may be constructed in the manner described above from DuPont's 22/1 (wor~ted count) Orlon 44 high bulk acrylic yarn and Ea~tman's 12/1 Kodel 50/50 polyester/cotton yarn.
When the fabric is knitted of such yarns on a 10 gauge machine at a density of 15 stitches per inch off of the machine, the resulting fabric weighs approximately 7 ounces per square yard.
For a 10 gauge knitting machine, highly satisfactory insulating fabric will re~ult from the use of the yarns within the following ranges:
high bulk acrylic - 22/1-28/1 (worsted count) 50/50 polyester/cotton - 10/1-18/1 The combination of high bulk acrylic and blended polye~ter/cotton yarn~ i~ particularly advantageous in imparting improved ~hrinkage re~istance to the new fabric. Whereas fabric~ knit of high bulk acrylic yarn tend to balloon out, particularly width-wise, as the result of repeated launderings, fabrics knit of polyester/cotton yarn tend to shrink width-wise as well a~ length-wise as a re~ult of repeated launderings. In the in~ulating fabric of this invention, the inherent tendency of the high bulk acrylic yarn to balloon as the result of repeated launderings neutralizes the tendency of the poly/cotton yarn to shrink, with the result the fabric of this invention has virtually no width-wise ~hrinkage and has increased resistance to length-wise shrinkage. Thus, it is essential to knit a balanced fabric from the two quite disparate yarn~.
Careful consideration mu~t be given to ~electing acrylic and polyester/cotton yarns of compatible size in the knitting of the insulating fabric of this invention.
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While it is preferred that the yarn forming the outside or knitted framework of the fabric be composed of a blend of 50~ polyester and 50~ cotton, some variation in that ratio is acceptable. However, 100%
cotton yarn is not deemed to be satisfactory. It lacks sufficient stability to provide the requisite knitted frame for anchoring and stabilizing the high bulk acrylic yarn in the fabric. 100~ polyester yarn also is unsatisfactory, notwithstanding its inherent stability. It is not sufficiently absorbent and its hand tends to be har~h.
After the fabric has been knitted and removed from the knitting machine, it is subjected, while in tubular form, to a series of post-knitting finishing operations which are depicted schematicàlly in Fig. 3. As illu~trated by that Figure, the fabric i~ subjected to the following fini~hing operations:
(1) scouring - a conventional process whereby the fabric is subjected to an aqueous bath to remove dirt, oil, grease and other impurities;
INSULATING FABRIC AND METHOD OF MANUFACTURE THEREOF
Background of the Invention This invention pertains to fabrics designed and intended primarily for use in winter weight underwear.
I~owever, since the fabrics of the invention have an insulating quality, their use is not limited to winter underwear garments. They have utility wherever fabric warmth i~ desired, for example, in the manufacture of sweaters, sportswear, blankets and the like.
From time immemorial it was conventional for winter underwear fabrics to be sold by weight, for the reason that, in general, the heavier the fabric the warmer the garments made from it. The reason for this iB that textile fibers entrap air to a substantial degree, and it is the entrapped air which gives a fabric its insulating quality. Thus~ the insulating or thermal effectiveness of a fabric u~ed in making cold weather garments, such a~ winter underwear, i~
;determined by the amount of air entrapped in the fabric. Accordingly, in the days of yore, winter wear - 20 fabrics were designed on the theory that the heavier the fabric by weight, the warmer it would be.
In more recent years, however, fabric designers have developed new fabrics constructed with air-entrapping cells or pockets on one or both sides which provide dead air spaces in the fabric. Such fabric structures trap more air than that entrapped by the fibers alone, and thus enhance the insulating quality of the fabric. Knitted fabrics constructed with a multitude of such air pockets or air-entrapping cells are known as "thermal" fabrics.
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. ", . ~ .
3L295~90 The air-entrapping cells in such fabrics are three dimensional cavities having spaced top, bottom and side walls and a floor, which trap and retain air warmed by the heat of the human body. The trapped air gives the fabric an enhanced heat insulating or heat retention quality, thus adding to it insulation, warmth or "thermal" quality.
The original thermal fabric, first known as "waffle knit" fabric, was developed by the United States Navy for military u~e in about 1951. The Navy's waffle knit fabric is a flat, warp knit fabric made on a double needle bar raschel knitting machine. It soon found acceptance for civilian use in underwear, and became known popularly as "thermal underwear". A brief history of the Navy IB waffle knit raschel thermal fabric will be found in Professor William E. Schinn's article "The Philip Model PT/RR Machine" published in the April 1968 issue of "'rhe Knitter" magazine, beginning at page 37.
A great interest soon arose in the underwear industry for developing a competing weft knit thermal fabric which could be made on conventional circular knitting machines. A weft knit thermal fabric eventually was developed, for which Morgan United 25 States Patent No. 2,839,909 was granted. The Morgan patented fabric is made on a multifeed circular rib knitting machine having dial and cylinder needles disposed in a 2 x 2 rib knitting arrangement. Its air-entrapping cells are produced by alternate triple tucking, first on one ~et of needles, then on the other set of needles, the non-tucking needles knitting plain stitche~. The Morgan thermal fabric is characterized by spaced groups of tuck strands extending across the ~, .. .. . .
`` 12~35490 valleys formed between the ribs of the fabric, the ribs forming the ~ide walls of the air-entrapping cells and the spaced tuck strands forming the top and bottom walls of the cells.
Later on, a second weft knit thermal fabric was developed utilizing the Philip Model PT/RR knitting machine, for which Philip United States Patent No.
3,568,475 was granted. The PT/RR machine is a multifeed 1 x 1 circular rib knitting machine using the flexer principle to rack the dial needles. In knitting the Philip patented fabric, the machine is arranged for knitting a full cardigan fabric. Selective racking of the dial needles is utilized, whereby the needles assume a 2 x 2 rib relation~hip during knitting of the fabric. Because the air-entrapping cells in succeeding rows in the Philip thermal fabric are staggered, the fabric more nearly 3imulates the raschel thermal fabric in appearance than does the earlier Morgan thermal fabric.
Subsequently, a third weft knit thermal fabric was introduced by J.E. Morgan Knitting Mills, Inc. of i Tamaqua, Pennsylvania which simulates yet more closely in appearance the raschel knit thermal fabric. This fabric is known in the trade as "circular raschel"
because of its close simulation to the raschel thermal fabric. It is composed of repetitive sequences of knit, tuck and welt stitches which produce multiple air-entrapping cells disposed in staggered relationship on both sides of the fabric. The circular raschel thermal fabric also is knitted on a 1 x 1 circular rib knitting machine. Needle selection means are operative to select needles in alternating and repetitive sequences for knitting, tucking and welting in ~' :, , ~295490 recurring cycles to produce a weft knit thermal fabric incorporating air-entrapping cells constructed of knitted stitches, tuck loops and floats.
For many years winter wear garments made from the raschel, Morgan, Philip and circular raschel thermal fabrics have been sold in the United States. The manufacture and sale of such thermal garments still is taking place.
In the knitting of fabrics generally, it is old practice to knit two or more yarns into a fabric in such a manner that one of the yarns appears on one face of the fabric and a different yarn appears on the opposite face of the fabric. In weft knitting, "plating" is a common practice in hosiery manufacture, wherein fabric is knitted of two yarns which may differ in color or other characteristic. The plated fabric is knit ~o that one yarn is visible on one side thereof and the other yarn is visible on the opposite side.
Morancy U.S. Patent No. 2,946,210 discloses a rib knit fabric formed of inelastic, elastic and stretch yarns and knitted so that the stretch yarn appears on the inner side of the fabric to provide a relatively soft texture, while the inelastic yarn i~ disposed on the outer face of the fabric to provide a relatively stiff and smooth texture.
Napping is a decades-old practice in which a small portion of the yarns on one or both sides of a knitted or woven fabric are raised mechanically to provide a fibrous surface. Usually, napping is carried out by causing the fabric to pass over a rotatable cylinder having teeth or spikes on its periphery which pick up the surface fibers of the yarns to a slight extent without tearing or otherwise damaging the fabric.
~295490 ;~organ U.S. Patent 2,839,909 aforesaid discloses the napping of a knitted thermal fabric.
Summary of the Invention The insulating fabric of this invention is characterized by a knitted base fabric having air-entrapping cells. The fabric preferably is knit from a bulk or high bulk acrylic yarn and a combination polyester and cotton yarn. The yarns are fed to the knitting machine needles separately at selected yarn feeds. The inner face of the fabric is formed of the acrylic yarn. The outer face of the fabric is formed of the combined polyester and cotton yarn. The polyester/cotton yarn provides an exterior knitted framework for anchoring and stabilizing the acrylic yarn in the fabric. The inner fabric surface formed of the acrylic yarn provide3 a soft texture and a warm, comfortable feel or hand when the fabric i~ worn next to the ~kin, as in the ca~e of thermal underwear.
The primary object of this invention is to provide a new and improved knitted insulating fabric for use in the manufacture of winter wearing apparel, such as underwear, which is warmer, lighter in weight, more comfortable in wear and more resistant to shrinking than knitted fabrics heretofore made and ~old, and which is characterized by an ability, as the result of -; several machine washings, to increase both in thickness and warmth by at least 25%.
A further object of the invention is to provide a new and improved knitted insulating fabric having a bulk yarn knit in selected courses in the fabric, the ~; bulk yarn being disposed on one surface of the fabric and being anchored and stabilized therein by a knitted framework composed of a combined ~ynthetic/cotton yarn.
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In a preferred arrangement, a high bulk yarn is knit in alternating courses of the fabric and the combined synthetic/cotton yarn is knit in the intervening courses of the fabric.
A further object is to provide a new and improved insulating fabric having a base fabric constituted of knitted thermal fabric having air-entrapping cells, the fabric being knit of high bulk acrylic and blended polyester/cotton yarns disposed separately in selected courses, the fabric being characterized by stability, light weight with increased warmth, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and an inherent capacity, upon repeated washings, to increase substantially in bulk, thickness and warmth.
Yet a further object of the invention i~ to provide a new and improved lightweight insulating fabric having a ba~e fabric incorporating air-entrapping cells, the fabric being knit of medium weight acrylic bulk yarn and medium weight blended polyester/cotton yarn disposed separately in selected courses. The fabric is characterized by stability, increased warmth despite its relatively light weight, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and an inherent capacity, upon repeated washings, to increase substantially in bulk, thickness and warmth.
A further object is to provide a method of knitting new and improved insulating fabrics which permits bulk yarns, particularly high bulk acrylic yarn, to be knit succe~sfully into the fabric and to be stabilized and retained therein during subsequent textile finishing operations, including napping, and during repeated wear and laundering.
~29~490 Other objects and advantages of this invention will be readily apparent from the following description of preferred embodiments thereof, reference being had to the accompanying drawing.
Description of the Views of the Drawing Fig. l is an enlarged, fragmentary view illustrating schematically a preferred weft knit thermal fabric utilized in the practice of this invention.
Fig. 2 is a knitting diagram showing schematically the operation of the cylinder and dial needles in knitting successive courses of the thermal fabric illustrated in Fig. l of a l x l circular rib knitting machine.
Fig. 3 is a schematic view of flow-sheet character illustrating the preferred sequence of manufacturing steps utilized in making an insulating fabric embodying this invention.
Fig. 4 is a graph depicting the characteristic of the insulating fabric of the invention of first increasing and then stabilizing in thickness a~ a result of repeated washings, thereby adding bulk and warmth to the fabric.
Fig. 5 is an unmagnified photograph showing the inner faces of two identical swatches of an insulating fabric incorporating this invention, the fabric on the left being unwashed and that on the right having been washed ten times.
Fig. 6 is a photograph magnified thirty times, showing in side elevation the relative thickness of the two fabrics illustrated in Fig. 5, the upper fabric ;~ being the unwashed fabric and the lower fabric being : the fabric which had been washed ten times.
. . .
129~;490 Fig. 7 is a second knitting diagram showing schematically the operation of the cylinder and dial needles in knitting an alternative weft knit thermal fabric utilized in the practice of this invention.
Fig. 8 is a third knitting diagram showing schematically the operation of the cylinder and dial needles in knitting a modified insulating fabric in accordance with this invention.
Detailed Description of the Invention The insulating fabric of this invention may be incorporated into any known knitted thermal fabric having air-entrapping cell~ formed on one or both sides of the fabric. For more effective insulation, however, it i~ preferred that the air-entrapping cells be formed on both sides.
Figure~ 1-6 of the drawing depict the ernbodiment of the invention which utilizes as the ba~e fabric the circular raschel type of thermal fabric having air-entrapping cells on both ~ides constructed of a combination of knitted stitches, tuck loops and floats concatenated in a selected sequence.
Referring first to Fig. 1, where a portion of a circular ra~chel thermal fabric 10 is shown schematically, there are illustrated successive course-wi~e extending rows 11, 12, 13, 14, 15 of plural air-entrapping cells 17. The cells 17 are defined by course-wise spaced side walls 19, 20 and wale-wise spaced top wall~ 21 and bottom walls 22. Each cell i~
provided with a floor 23 disposed intermediate the ~paced side, top and bottom walls.
Tha base fabric 10 depicted in Fig. 1 i~ a 1 x 1 rib knitted fabric made on a multi-feed weft knitting machine having opposed needle bank~. Preferably, the 12~S4~1~
g needles are independently mounted in each of the needle banks with capacity to be raised and lowered selectively to clear level, tuck level, welt level and cast-off level, utilizing well known and conventional needle ~electing means, to produce rib knitted fabric incorporating the stitchei, tuck loops and floats which form the air-entrapping cells 17 in the fabric.
A suitable knitting machine for producing the thermal fabric 10 depicted in Fig. 1 is the Albi ROFS
16 feed, coarse gauge, body size, circular rib knitting machine. The Albi machine is provided with a rotatable cylinder and dial, each incorporating a plurality of independent needle~ alternating in a 1 x 1 arrangement.
Positive yarn feeding means are utilized, such as furnishing wheels, to feed yarn to the needle~ at each of the yarn feeds at a selected rate of feed. A 10 cut machine is preferred, having a needle cylinder diameter within the range of 12" to 17" for knitting body size tubular fabric. The machine preferably is operated to knit a 16 feed, 8 repeat stitching cycle, shifting the knitting pattern after 4 repeat~ to provide the in-and-out effect necessary to form the air-entrapping cells 17 in staggered relation throughout the fabric.
To ensure a tight knit fabric, the yarn i9 fed to the needles under a relatively heavy tension, a~ is usual in knitting thermal fabrics.
Fig. 2 illu~trates the preferred method for knitting the thermal fabric 10 on a 16 feed circular rib knitting machine. The vertical columns denoted C
and D refer to individual needles mounted on the cylinder and on the dial, respectively. The horizontal row~q numbered 1, 2, 3, etc. to 16 identify consecutive yarn feeds spaced at uniform interval~ around the ~, , ~295~
needle cylinder of the machine. The letters T, K and W
indicate, respectively, whether the cylinder and dial needles tuck, knit or welt during the knitting process.
The knitting diagram constituting Fig. 2 of the drawing depicts the stitch structure of the fabric 10 as well as the method of knitting that fabric. In illustrating the fabric, the horizontal row of letters C, D, C, etc. depicts, in alternation, the cylinder needle wales and the dial needle wales of the fabric.
The vertical left-hand column of numbers 1, 2, 3, etc.
indicates the courses of the fabric. The letter K
identifies a knitted stitch, and the letter T indicates a tuck loop. The letter W indicates where a float is formed in the fabric when a needle is retained at welt level.
Fig. 2 depict~ one complete knitting cycle of the ba~e fabric 10 constituted of 16 yarn feed~/courses which produce, in the fabric, two successive course-wise extending row~ 11-15 of air-entrapping cells 17, the cells of adjacent rows being staggered relative to each other.
As the knitting diagram of Fig. 2 illustrates, during knitting of the first 8 courses of a fabric cycle, all of the dial needles produce knitted stitches at the alternate yarn feeds 1, 3, 5 and 7. At those feeds the alternate cylinder needles are lowered to welt level to produce floats in the fabric, while the intervening cylinder needles are tucked to produce tuck loops. Meanwhile, at the intervening yarn feeds, 2, 4 6 and 8 the cylinder needles produce knitted stitche~, alternate dial needles produce tuck loop~ and the intervening dial needles are welted to produce yarn floats.
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During the knitting of the second 8 courses of the fabric cycle, at yarn feeds 9 to 16 inclusive, the knitting sequence is shifted to provide the in-and-out effect which creates the staggered air-entrapping cells 17 in successive rows 11-15 of the fabric 10. At the alternate yarn feeds 9, 11, 13 and 15, all dial needles continue to produce knitted stitches, but the cylinder needles are operated in reverse sequence. Alternate cylinder needles are tucked to produce tuck loops, while the intervening cylinder needles are welted to produce yarn floats. At the intervening yarn feeds 10, 12, 14 and 16, the cylinder needles continue to form knitted stitches, but the dial needles operate in reverse sequence, with the alternate dial needles welting to produce yarn floats and the intervening dial needles producing tuck loop~.
The cycle of knitting depicted in Fig. 2 i~
repeated ~ucce~ively during the knitting of the fabric 10 to provide a fabric incorporating on each side a plurality of course-wise extending row~ of air-entrapping cells 17, exemplified by rows 11-15, with the individual cells 17 of each row staggered relative to the cell~ of its adjacent rows.
In knitting the insulating fabric depicted in Figs. 1-6, high bulk 100% acrylic yarn i9 fed to the needles at the alternate yarn feeds 1, 3, 5, 7, 9, 11, 13, 15 while a blended polyester and cotton yarn is fed to the needles at the intervening yarn feeds, 2, 4, 6, 8, 10, 12, 14i 16. As a reqult, the acrylic yarn appears on the inside face of the fabric and the combined polyester and cotton yarn appears on the out3ide face of the fabric.
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Becau~e of its low moisture absorbency, ability to dry quickly, warmth characteristics, high bulk to weight ratio and soft, pleasant and resilient hand, the desirability of using high bulk acrylic yarn for knitting winter weight underwear long has been recognized. But high bulk acrylic yarn does not readily lend itself to the satisfactory knitting of fabrics. Because of the bulked character of such yarn, the resulting fabric is unstable, and is subject to ballooning, particularly width-wise, as a result of repeated launderings. Even during the knitting process, while still on the machine, the newly knitted fabric tends to balloon. For that reason, high bulk acrylic yarn has not been found to be satisfactory for knitting underwear fabrics.
The invention provide~ a solution to the in~tability problem inherent in the knitting of high bulk acrylic yarn. Knitting such yarn in combination with a blended polyester and cotton yarn introduces into the fabric the stability necessary to enable the knitting of commercially acceptable underwear fabrics from high bulk acrylic yarn. The problem of the ballooning of the fabric, both during the knitting process and as the result of subsequent laundering, i9 eliminated. And the finished fabric incorporates sufficient rigidity to maintain fabric stability during all of the po~t-knitting processes, such a~ scouring, drying, calendering, cutting and sewing, and during subsequent garment wear and laundering. In the fini~hed fabric, the polyester/cotton yarn, which appears on the outside of the fabric, provides a relatively rigid knitted framework for anchoring and stabilizing the high bulk acrylic yarn which forms the inner face of the fabric.
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A highly satisfactory insulating fabric may be constructed in the manner described above from DuPont's 22/1 (wor~ted count) Orlon 44 high bulk acrylic yarn and Ea~tman's 12/1 Kodel 50/50 polyester/cotton yarn.
When the fabric is knitted of such yarns on a 10 gauge machine at a density of 15 stitches per inch off of the machine, the resulting fabric weighs approximately 7 ounces per square yard.
For a 10 gauge knitting machine, highly satisfactory insulating fabric will re~ult from the use of the yarns within the following ranges:
high bulk acrylic - 22/1-28/1 (worsted count) 50/50 polyester/cotton - 10/1-18/1 The combination of high bulk acrylic and blended polye~ter/cotton yarn~ i~ particularly advantageous in imparting improved ~hrinkage re~istance to the new fabric. Whereas fabric~ knit of high bulk acrylic yarn tend to balloon out, particularly width-wise, as the result of repeated launderings, fabrics knit of polyester/cotton yarn tend to shrink width-wise as well a~ length-wise as a re~ult of repeated launderings. In the in~ulating fabric of this invention, the inherent tendency of the high bulk acrylic yarn to balloon as the result of repeated launderings neutralizes the tendency of the poly/cotton yarn to shrink, with the result the fabric of this invention has virtually no width-wise ~hrinkage and has increased resistance to length-wise shrinkage. Thus, it is essential to knit a balanced fabric from the two quite disparate yarn~.
Careful consideration mu~t be given to ~electing acrylic and polyester/cotton yarns of compatible size in the knitting of the insulating fabric of this invention.
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While it is preferred that the yarn forming the outside or knitted framework of the fabric be composed of a blend of 50~ polyester and 50~ cotton, some variation in that ratio is acceptable. However, 100%
cotton yarn is not deemed to be satisfactory. It lacks sufficient stability to provide the requisite knitted frame for anchoring and stabilizing the high bulk acrylic yarn in the fabric. 100~ polyester yarn also is unsatisfactory, notwithstanding its inherent stability. It is not sufficiently absorbent and its hand tends to be har~h.
After the fabric has been knitted and removed from the knitting machine, it is subjected, while in tubular form, to a series of post-knitting finishing operations which are depicted schematicàlly in Fig. 3. As illu~trated by that Figure, the fabric i~ subjected to the following fini~hing operations:
(1) scouring - a conventional process whereby the fabric is subjected to an aqueous bath to remove dirt, oil, grease and other impurities;
(2) padding - following scouring, the fabric is processed in a padding machine, where the wet fabric tube is reopened, laterally extended, impregnated with a softener, padded and then laid up in folds;
(3) drying - following padding, the fabric is pa~sed through a conventional textile dryer, where it is overfed a~ it is dried to improve fabric stability and control shrinkage, following which the fabric again is laid up in fold~;
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(4) napping - following drying, the tubular fabric is turned inside out to place it~ acrylic face on the outside of the fabric tube, following which the acrylic surface of the fabric is napped lightly twice in a conventional napping machine; following napping, the fabric is turned right side out to restore it~
napped acrylic face to the inside of the fabric tube;
(S) calendering - following napping, the fabric is finished by calendering on a conventional tensionles3 calender, where the fabric is uniformly stetched width-wise to the desired width and subjected to steam to relax the yarn3 and set the 3titches, thereby imparting dimensional 3tability to the fabric.
Following calendering, the fabric is ready for cutting and sewing into garments.
As is well known, all thermal fabrics knitted of cotton yarn will, over the first several machine washings, increase in fabric thickne~ and in heat retention quality to some degree. These changes are due to shrinkage of the fabric during launderingt as a result of which the fabric structure becomes more compact, and the weight of the fabric increases slightly per 3quare yard. After five or six machine washings, the fabrics tend to stabilize and manifest generally constant value3 of fabric thickness, heat retention and shrinkage. Eventually, after about ten launderings, such fabrics may begin to exhibit fiber los~, re3ulting in relatively minor decrea~e3 in fabric weight and sometimes, also, in fabric thickness.
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Early mill tests of the insulating fabric of this invention, as depicted in Figs. 1-6, revealed that the fabric achieved the following new, surprising and unexpected result~:
1. As the fabric is laundered, up to about six machine washings, it increases significantly in warmth, up to 25~ or more;
2. As the result of repeated machine washings, the fabric increases substantially in thickness, on the order of 33-1/3~ or higher, thereby enhancing its ability to trap air; after about 10 washings, the increased thickness of the fabric tends to stabilize;
3. The napped inner face of the fabric does not become compressed or matted as the result of repeated washings, which would be normal; instead the acrylic inner surface increases in loft, adding bulk to the fabric;
4. Despite repeated laundering, the fabric retains its stability notwithstanding its large content of high bulk acrylic yarn;
napped acrylic face to the inside of the fabric tube;
(S) calendering - following napping, the fabric is finished by calendering on a conventional tensionles3 calender, where the fabric is uniformly stetched width-wise to the desired width and subjected to steam to relax the yarn3 and set the 3titches, thereby imparting dimensional 3tability to the fabric.
Following calendering, the fabric is ready for cutting and sewing into garments.
As is well known, all thermal fabrics knitted of cotton yarn will, over the first several machine washings, increase in fabric thickne~ and in heat retention quality to some degree. These changes are due to shrinkage of the fabric during launderingt as a result of which the fabric structure becomes more compact, and the weight of the fabric increases slightly per 3quare yard. After five or six machine washings, the fabrics tend to stabilize and manifest generally constant value3 of fabric thickness, heat retention and shrinkage. Eventually, after about ten launderings, such fabrics may begin to exhibit fiber los~, re3ulting in relatively minor decrea~e3 in fabric weight and sometimes, also, in fabric thickness.
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Early mill tests of the insulating fabric of this invention, as depicted in Figs. 1-6, revealed that the fabric achieved the following new, surprising and unexpected result~:
1. As the fabric is laundered, up to about six machine washings, it increases significantly in warmth, up to 25~ or more;
2. As the result of repeated machine washings, the fabric increases substantially in thickness, on the order of 33-1/3~ or higher, thereby enhancing its ability to trap air; after about 10 washings, the increased thickness of the fabric tends to stabilize;
3. The napped inner face of the fabric does not become compressed or matted as the result of repeated washings, which would be normal; instead the acrylic inner surface increases in loft, adding bulk to the fabric;
4. Despite repeated laundering, the fabric retains its stability notwithstanding its large content of high bulk acrylic yarn;
5. The fabric ha~ increased resistance to shrinkage, which is especially ~urprising in view of the large increase in fabric thicknes~ after several machine washings;
6. The fabric, weighing approximately 7 ounceq per square yarn, is warmer than conventional thermal fabric knit of 100% cotton yarn and weighing approximately 9 ounces per square yarn.
The fabrics depicted photographically in Figs. 5 and 6 of the drawing illustrate the physical changes which take place after the fabric has been subjected to 10 machine washings. Fig. 5 shows the inner acrylic :
~ face of two swatches of fabric knit and fini~hed in I
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accordance with Figs. 1-3 of the drawing. The fabric on the left-hand side of Fig. 5 is unwashed, and that on the right-hand side has been washed 10 ti~es.
Comparison of the two fabrics reveals significant changes in the appearance of the inner acrylic surface of the washed fabric. The acrylic fibers have increased in loft or bulk, and the inner fabric face appears to be covered by a thin film of such fibers.
Further, the air-entrapping cells have increased slightly in both width and depth, thereby increasing their air-entrapment capability.
The changes which have occurred in the washed fabric are illustrated even more dramatically in Fig.
6, where edge views of the two fabrics are illustrated.
In Fig. 6, the upper fabric is the unwashed fabric and the lower fabric is the washed fabric. Comparison of the two fabrics, as depicted in Fig. 6, reveals that the thickness of the lower fabric, washed 10 times, is approximately 51% greater than the thickness of the upper, unwashed fabric.
During repeated machine washings, the napped acrylic surface of the fabric i8 continually combed out by the agitation of the wa~hing machine, with the result that not only i~ its original loft maintained, rather than becoming matted, but the fibrous acrylic surface of the fabric actually increases in bulk. It is thi~ phenomenon which enables the fabric, a~ the result of repeated machine wa~hings, to enhance its ability to trap air, thus increasing its heat retention quality.
The results of the initial mill tests of the new fabric, described above, have been confirmed by independent laboratory tests conducted by Ea~tman Chemical Products, Inc. in Kingsport, Tennessee and by ' ,.. . . .
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The Philadelphia College of Textiles & Science, in Philadelphia, Pennsylvania. soth laboratories conducted thermal tran~mittance tests of the new fabric in comparison with the triple tuck 2 x 2 rib knitted thermal fabric disclosed in Morgan U.S. Patent 2,839,909. The insulating fabric of this invention used in those te~t3, was knit and finished in accordance with Figs. 1-3 of the drawing. The yarns were DuPont's Orlon 44 acrylic yarn and Eastman's Kodel polyester/cotton yarn previously specified, and the fabric weighed approximately 7 ounces per square yard.
The comparison thermal fabric used in the tests was knit entirely of 12/1 cotton yarn on a 12 cut machine, and weighed approximately 9 ounces per square yard.
Both the Eastman and Philadelphia College laboratory tests were conducted in accordance with ASTM
're~t D1518, which i~ the ~tandard te~t method for determining the thermal transmittance of textile material~. In conducting that test, and interpreting the results, the following definitions are especially relevant:
Ul - combined thermal transmittance of the test fabric and air U2 - thermal tran~mittance of fabric only 5 clo - unit of thermal resistance defined as the in~ulation required to keep a resting man comfortable in an environment at 21C, air movement of 0.1 m/s, or roughly the insulation value of typical indoor clothing 0 R - The intrinsic thermal resistance of the fabric alone It is important to ob~erve, in te~ting and evaluating textile fabrics for their heat insulating or ~L2~5490 thermal value, that the lower the values or coefficients Ul and U2 are, the better. And the higher the values clo and R are, the better.
The result~ of the Eastman and Philadelphia College fabric tests are ~et forth in the tables which follow. In examining the data, one must be cautioned, as explained in ASTM D1518, that the thermal testing of fabrics i5 an extremely complicated subject which involves many factors, so that measured thermal transmittance coefficients necessarily are only indicative of the relative merits of particular fabrics. Further, it mu~t be remembered that the knitting of fabrics is, at best, an inexact science.
Many uncontrolled and uncontrollable factor~ come into play, ~uch as the usual variables in yarn processing, knitting machine operation, fabric finishing, laundering, etc. Accordingly, the te~t data reproduced below must be evaluated les~ in absolute terms than in relative or indicative results.
In the tables of data set forth below, ~abric A is the insulating fabric of the invention depicted in Fig~ 6, and Fabric B i~ the comparison Morgan patented thermal fabric described above. Test No. 1 was conducted by Eastman, and Test No. 2 by Philadelphia College. All test fabric~ had been napped.
TEST NO. 1 (Eastman) Fabric A Number of Machine Wa~hing~
30 Ul 0.9925 0.88380.8~92 2 2.514 1.917 1.849 clo 0.4523 0.59320.6149 ll R 0.3978 0.52170.5408 ; Fabric Thickne~s 0.095"0.132" 0.142"
35 Fabric Weight 6.970 8.130 7.890 (oz/sq. yd.~
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, "" , ~Z~5490 Fabric B Number of Machine Washings Ul 1.0170.9802 0.9916 U2 2.6762.436 2.508 clo 0.42490.4667 0.4534 R 0.37370.4104 0.3987 Fabric Thickness 0.120" 0.146" 0.144"
Fabric Weight 9.20011.150 10.860 (oz/sq. yd.) 10 As the above data reveal, after 10 machine washings the insulating fabric of the invention had increased in thickness approximately 49%. Its thermal resistance had increased approximately 36%. Although the thickness of the comparison thermal fabric had increased approximately 20~, its thermal resistance had increased only 7%.
In Fig. 4, the upper curve, denoted "Test No. 1", illustrate~ empirically the approximate growth in thickness of the insulating fabric of the invention according to the Eastman te~t data.
TEST M0. 2 (Philadelphia College) Fabric A Number of Machine Washing~
U 21.925 14.391 14.17917.659 25 clo 0.295 0.449 0.456 0.366 R 0.046 0.069 0.071 0.057 Fabric Thickness 0.072" 0.082"0.092" 0.101"
Fabric Weight6.770 7.970 7.710 7.350 (oz/sq. yd.) TEST N0. 2 (Philadelphia College) Fabric B Number of Machine Washings ., :, 0 1 5 10 ; U 24.581 25.029 19.257 26.810 clo 0.263 0.258 0.336 0.241 R 0.041 0.040 0.052 0.037 Fabric Thickness 0.091" 0.111" 0.116" 0.072"
Fabric Weight 8.910 10.680 11.360 10.310 ~1 (oz/sq. yd.) ', 3~2~
According to the above data from the Philadelphia College laboratory test, after 5 machine washings the insulating fabric of the invention had increased in thickness by approximately 28~, and its S thermal resistance had increased approximately 54%.
After 5 machine washings, the thickness of the comparison thermal fabric had increased 27~, but its increase in thermal resistance was only 27%.
After 10 washings, both test fabrics exhibited a decline in thermal resistance, but the decline in the compari~on fabric was greater than that in the fabric of the invention. After 10 washings, the thickness of the comparison fabric had reduced drastically, whereas the thickness of the fabric of the invention continued to increase.
In Fig. 4, the lower curve, denoted "Test No. 2", illu~trates empirically the approximate growth in thickne~s of the insulating fabric of the invention according to the Philadelphia College test data.
Notwithstanding the comparison fabrics in the two above te~ts were more than 2 ounces per square yard heavier than the insulating fabrics of the invention, the test data confirmed the superior thermal or heat retention properties of the fabric of the invention.
As indicated previously, the insulating fabric of this invention may include as its base fabric any knitted thermal fabric incorporating air-entrapping ;~ cells. A highly satisfactory insulating fabric embodying this invention may be made utilizing as its base fabric the triple tuck 2 x 2 rib knitted thermal fabric disclosed in Morgan U.S. Patent 2,839,909 aforesaid. Fig. 7 of the drawing depicts the knitting diagram for that fabric, illustrating both the method used in knitting the fabric as well as its stitch structure.
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In Fig. 7, the horizontal letters D, D, C, C, D, etc. denote individual needles mounted 2 x 2 on the dial and on the cylinder, re~pectively, of the knitting machine when Fig. 7 i~ read a~ the method of knitting.
Those letters also depict the 2 x 2 alternating dial and cylinder needle wales in the knitted fabric. The vertical left-hand column of numbers 1, 2, 3, etc.
identifies consecutive yarn feeds of the circular knitting machine used, and also depicts the fabric courses knitted at those yarn feeds. The letters T and K indicate, re~pectively, in the knitting process, whether the cylinder and dial needles tuck or knit.
Those letter~ also identify, respectively, the tuck loops and knitted stitches in the fabric.
The knitting diagram of Fig. 7 illu~trates one complete 8 course cycle of knitting, which is repeated successively on the knitting machine to produce thermal fabric having air-entrapping cells on both sides.
In utilizing that thermal fabric as the base fabric for this invention, a high bulk 100~ acrylic yarn is fed to the needles of the knitting machine at yarn feeds 4, 5, 6, 7, while the polyester/cotton yarn is fed to the needles at yarn feed~ 1, 2, 3 and 8. In ~uch arrangement, at yarn feeds 1, 2 and 3 the polyester/cotton yarn is tucked on the dial needle~ and knitted on the cylinder needle~. At yarn feed 4, where the high bulk acrylic yarn is fed, all needles knit, thus ca~ting the triple tucks of poly/cotton yarn off of the dial needles.
At yarn feeds 5, 6, 7, the acrylic yarn is tucked by the cylinder needles and knitted by the dial needles. At yarn feed 8, where the polyester/cotton yarn is fed, all needles knit so that the triple tuck~
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of acrylic yarn on the cylinder needles are ca~t off.
As a result, the high bulk acrylic yarn appears on the inside face of the tubular fabric. The combined polyester and cotton yarn appear~ on the outside face of the fabric, and provides the necessary knitted frame or framework for anchoring and stabilizing the acrylic yarn.
Insulating fabric in accordance with Fig. 7 was knit on an 8 feed, 12 cut circular rib knitting machine. The yarns used were DuPont's 22/1 (worsted count) Orlon 44 high bulk acrylic yarn and Eastman's 18/1 Kodel 50/50 polyester/cotton yarn. The fabric, when removed from the knitting machine, weighed approximately 7.5 ounces per square yard. Normally, commercial triple tuck thermal fabric made in accordance with ~organ U.S. Patent 2,839,909 weighs approximately 9 ounces per square yard.
The insulating fabric, knit in accordance with the specifications described above, was subjected to a series of 10 machine washings as a result of which the fabric added bulk and increa~ed in thickness by .046", or approximately 33-1/3%. The original fabric thickness, prior to the first washing was .138". Its thickness after the tenth washing was .184". Set forth below i9 a table illustrating the thickness of the fabric following each of the ten machine washings to which it was subjected:
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Number ofFabric Thickness Machine WashingsAfter Each Washing original (unwashed).138"
1st washing .166"
2nd washing .170"
3rd washing .172"
4th washing .179"
5th washing .179"
6th washing .184"
7th wa~hing .176"
8th wa~hing .188"
9th washing .166"
10th washing .184"
It will be ob~erved, from the foregoing table, that the knitted fabric continued to increase in thickness through the first ~ix machine wa~hings, following which the thickne~ of the fabric tended to stabilize. As a result of the several wa~hings, and the concomitant increase in thickne~, due to increased bulk or loft, the fabric enhanced its air-entrapping capacity, acquired a greater heat retention quality and thus became a warmer fabric than it was before it was ; washed.
Fig. 8 of the drawing depicts the knitting diagram for a modified weft knit insulating fabric made in accordance with thi~ invention. The fabric is made on a circular 2 x 1 rib knitting machine in which pairs of independent type cylinder needle~ alternate around the needle circle with single, independent type dial needles. Preferably, the machine ha~ eight yarn feed~, or multiple~ thereof. Fig. 8 illustrates both the method used in knitting the modified insulating fabric a~ well a~ its stitch structure.
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In Fig. 8, the horizontal letters C, C represent the pairs of cylinder needles which alternate with the single dial needle~ D for carrying out 2 x 1 rib knitting on the machine. Those letters also depict the S 2 x 1 alternating sequence of the cylinder and dial needle wales in the knitted fabric. The vertical left-hand column of numbers 1, 2, 3, etc. identifies the consecutive yarn feeds of the knitting machine and, also, indicates the fabric cour~es knitted at those yarn feeds. The letters K and T indicate, respectively, in the knitting process whether the needles knit or tuck. It will be observed from Fig. 8 that the alternating pairs of cylinder needles C always knit yarn, whereas the intervening ~ingle dial needles D tuck yarn at alternating yarn feeds and knit yarn at the intervening yarn feeds. The letters K, 'r also identify~ respectively, the knitted stitches and the tuck loops in the fabric.
The knitting diagram of Fig. 8 illustrates one complete eight cour~e cycle of knitting, which is repeated successively on the multi-feed circular 2 x 1 rib knitting machine utilized.
Preferably, a polyester/cotton yarn is fed to the knitting machine needles at yarn feeds 1, 3, 5 and 7, while a 100% acrylic bulk yarn is fed to the needles at yarn feeds 2, 4, 6 and 8. The dial needles are tucked at yarn feeds 1, 3, 5 and 7, thereby forming tuck loops of the poIyester/cotton yarn in spaced courses and ~paced wale~ of the fabric. Neither the dial nor the cylinder needles are tucked at yarn feeds 2, 4, 6 and 8.
In the fabric of Fig. 8, the acrylic bulk yarn appears on the inside face of the tubular fabric, while " .
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the combined polyester and cotton yarn appears on the outside face. The polyester/cotton provides the necessary knitted framework for anchoring and stabilizing the acrylic yarn in the fabric.
The outer, polyester/cotton yarn face of the fabric presents the usual 2 x 1 rib construction, in which wale-wise extending valleys one wale wide, knit by the dial needles D, alternate with wale-wise extending ribs two wales wide, knit by the cylinder needles C. The tuck loops formed from the polyester/cotton yarn by the dial needles D are disposed in spaced relation in the valleys on the outside of the fabric, thereby creating, in those valleys, a succes~ion of small, wale-wise extending lS air-entrapping cells on the outer face of the fabric.
The tuck loops constitute the top and bottom walls of the cells, and the adjacent rib~ constitute the side wall~ thereof. The floor of each cell, di~po~ed intermediate its spaced side, top and bottom walls, is constituted by the fabric of the valley. To ensure that the air-entrapping cells formed on the outside of the fabric have a three dimensional character, the yarns are fed to the needles of the knitting machine under relatively heavy tension to produce a tight knit fabric.
The inner face of the fabric has valleys two wales wide, formed by the cylinder needles C. The~e valleys are separated by wale-wise extending ribs one wale wide, knit by the dial needles D. Because the fabric is tight knit, the inside valleys are relatively deep, and are covered or overlaid by fibers of the acrylic bulk yarn. As a result, the inner valleys have an enhanced air-entrapping capacity and function as ':`
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elongated, continuous air-entrapping cells, thereby increasing the insulating character of the fabric.
In knitting a relatively heavy weight insulating fabric in accordance with the modification of Fig. 8, a 10 cut circular rib knitting machine preferably is used. The yarns may be of the character previously referred to such as, for example, DuPont's 22/1 (worsted count) Orlon 44 high bulk acrylic yarn and Eastman's 12/1 Kodel 50/50 polyester/cotton yarn.
However, the modification depicted in Fig. 8 also may be utilized, in the practice of this invention, for knitting a relatively lightweight insulating fabric.
For example, the fabric can be knit on a 14 cut circular rib knitting machine utilizing medium weight yarns such as, for example, DuPont's 32/1 (worsted count) Orlon 75 bulk acrylic yarn and Eastman's 28/1 Kodel 50/50 polyester/cotton yarn.
Following knitting, the fabric preferably is subjected to the several finishing operations depicted schematically in Fig. 3, including a light napping of the inner, acrylic face of the fabric. However, in order to ensure proper width and shrinkage control of the finished lightweight fabric, it is preferred that the tubular fabric be knit of a diameter one inch less than the width at which the fabric is calendered on the tensionless calender. For example, if the fabric of Fig. 8 is knit on a body-size knitting machine having a 13" diameter needle cylinder, it is preferred that the tubular fabric be finished at a width of 14" on the tensionless calender. In the same vein, fabric knit on a machine having a 16" diameter needle cylinder should be finished by calendering to a tubular width of 17".
The finished fabric, following its removal from the ~' ., .
tensionless calender, should be of a relatively tight construction, on the order of 32 to 34 courses per inch. The weight of the finished fabric should be on the order of 4.25 to 4.40 ounces per square yard.
Lightweight insulating fabric of the type depicted in Fig. 8, knit in accordance with the foregoing machine, yarn and finishing specifications, embodies all of the new, important, surprising and desirable characteristics of this invention, including fabric stability, increased warmth despite its relatively light weight, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and the inherent capacity, upon repeated washings, to increase substantially in bulk, thickness and warmth.
A sample of the lightweight insulating fabric of Fig. 8, knit in accordance with the specifications described above~ was subjected to a series of ten machine washings. Following the ten washings, the fabric wa~ found to have increased in thickness by 40%, while its weight in ounces per square yard had increa~ed a mere 8%.
The shrinkage characteristics of the fabric also were impre~sive. After the ten washings, the fabric exhibited length-wise shrinkage of a mere 2%. After the first machine washing, the fabric shrank width-wise about 13%, but thereafter width-wise shrinkage stabilized.
Although preferred embodiments of this invention have been shown and described for the purpose of illustration, it is to be understood that variou~
changes and modifications may be made therein without departing from the spirit and utility of thi~
invention, or the scope thereof as set forth in the appended claims.
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~;~5~9I3 For example, yarns equivalent to the bulk acrylic and blended polyester/cotton yarns described above could be used in the successful practice of this invention. The bulk yarn may be other than acrylic, but alternate bulk yarns should provide properties of low absorbency, warmth, resilience and comfort comparable to high bulk acrylic yarn, as well a~ the capacity to be napped. The non-bulk yarn preferably should be composed partly of cotton, because of its inherent good hand and absorbency. While polyester is the preferred fiber to be blended with cotton in the non-bulk yarn, other synthetic fibers could be used in lieu thereof, provided the combination synthetic/cotton yarn provides the necessary characteristics of absorbency, quick drying, good hand and ~trength. The synthetic/cotton yarn selected must function to provide a relatively rigid knitted framework for anchoring and stabilizing the bulk yarn in the fabric.
Of course, a reasonable range of the knitting specifications utilized is permissible in the practice of the invention, depending on the desired weight of the finished fabric. For example, in knitting lightweight insulating fabric of the 2 x l rib type depicted in Fig. 8, use of polyester/cotton yarns within the range of 24/l to 28/l is well within the scope of the invention. Likewise, again depending on the desired weight of the finished fabric, the courses per inch of the fabric, following calendering, may range from 30 to 36 without impairment of the several advantages which characterize the invention.
Napping of the inner acrylic side of the fabric, of course, increases the insulation effect of the fabric. However, napping is not critical to the ., .
~954~
achievement of the advantages of the invention, and may be dispensed with, if desired. Fabrics incorporating the invention which have not been napped also exhibit the advantages of fabric stability, relative light weight with increased warmth, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and the capacity, upon repeated washings, to increase in bulk, thickness and warmth. The fabrics of the invention which have not been napped, upon repeated washings, steadily increase in bulk, but at a slower rate than the fabrics which have been napped.
The fabrics depicted photographically in Figs. 5 and 6 of the drawing illustrate the physical changes which take place after the fabric has been subjected to 10 machine washings. Fig. 5 shows the inner acrylic :
~ face of two swatches of fabric knit and fini~hed in I
I
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.. '' . :
:
, ` .
3 Z954g~
accordance with Figs. 1-3 of the drawing. The fabric on the left-hand side of Fig. 5 is unwashed, and that on the right-hand side has been washed 10 ti~es.
Comparison of the two fabrics reveals significant changes in the appearance of the inner acrylic surface of the washed fabric. The acrylic fibers have increased in loft or bulk, and the inner fabric face appears to be covered by a thin film of such fibers.
Further, the air-entrapping cells have increased slightly in both width and depth, thereby increasing their air-entrapment capability.
The changes which have occurred in the washed fabric are illustrated even more dramatically in Fig.
6, where edge views of the two fabrics are illustrated.
In Fig. 6, the upper fabric is the unwashed fabric and the lower fabric is the washed fabric. Comparison of the two fabrics, as depicted in Fig. 6, reveals that the thickness of the lower fabric, washed 10 times, is approximately 51% greater than the thickness of the upper, unwashed fabric.
During repeated machine washings, the napped acrylic surface of the fabric i8 continually combed out by the agitation of the wa~hing machine, with the result that not only i~ its original loft maintained, rather than becoming matted, but the fibrous acrylic surface of the fabric actually increases in bulk. It is thi~ phenomenon which enables the fabric, a~ the result of repeated machine wa~hings, to enhance its ability to trap air, thus increasing its heat retention quality.
The results of the initial mill tests of the new fabric, described above, have been confirmed by independent laboratory tests conducted by Ea~tman Chemical Products, Inc. in Kingsport, Tennessee and by ' ,.. . . .
~Z~5~g~
The Philadelphia College of Textiles & Science, in Philadelphia, Pennsylvania. soth laboratories conducted thermal tran~mittance tests of the new fabric in comparison with the triple tuck 2 x 2 rib knitted thermal fabric disclosed in Morgan U.S. Patent 2,839,909. The insulating fabric of this invention used in those te~t3, was knit and finished in accordance with Figs. 1-3 of the drawing. The yarns were DuPont's Orlon 44 acrylic yarn and Eastman's Kodel polyester/cotton yarn previously specified, and the fabric weighed approximately 7 ounces per square yard.
The comparison thermal fabric used in the tests was knit entirely of 12/1 cotton yarn on a 12 cut machine, and weighed approximately 9 ounces per square yard.
Both the Eastman and Philadelphia College laboratory tests were conducted in accordance with ASTM
're~t D1518, which i~ the ~tandard te~t method for determining the thermal transmittance of textile material~. In conducting that test, and interpreting the results, the following definitions are especially relevant:
Ul - combined thermal transmittance of the test fabric and air U2 - thermal tran~mittance of fabric only 5 clo - unit of thermal resistance defined as the in~ulation required to keep a resting man comfortable in an environment at 21C, air movement of 0.1 m/s, or roughly the insulation value of typical indoor clothing 0 R - The intrinsic thermal resistance of the fabric alone It is important to ob~erve, in te~ting and evaluating textile fabrics for their heat insulating or ~L2~5490 thermal value, that the lower the values or coefficients Ul and U2 are, the better. And the higher the values clo and R are, the better.
The result~ of the Eastman and Philadelphia College fabric tests are ~et forth in the tables which follow. In examining the data, one must be cautioned, as explained in ASTM D1518, that the thermal testing of fabrics i5 an extremely complicated subject which involves many factors, so that measured thermal transmittance coefficients necessarily are only indicative of the relative merits of particular fabrics. Further, it mu~t be remembered that the knitting of fabrics is, at best, an inexact science.
Many uncontrolled and uncontrollable factor~ come into play, ~uch as the usual variables in yarn processing, knitting machine operation, fabric finishing, laundering, etc. Accordingly, the te~t data reproduced below must be evaluated les~ in absolute terms than in relative or indicative results.
In the tables of data set forth below, ~abric A is the insulating fabric of the invention depicted in Fig~ 6, and Fabric B i~ the comparison Morgan patented thermal fabric described above. Test No. 1 was conducted by Eastman, and Test No. 2 by Philadelphia College. All test fabric~ had been napped.
TEST NO. 1 (Eastman) Fabric A Number of Machine Wa~hing~
30 Ul 0.9925 0.88380.8~92 2 2.514 1.917 1.849 clo 0.4523 0.59320.6149 ll R 0.3978 0.52170.5408 ; Fabric Thickne~s 0.095"0.132" 0.142"
35 Fabric Weight 6.970 8.130 7.890 (oz/sq. yd.~
~:
, "" , ~Z~5490 Fabric B Number of Machine Washings Ul 1.0170.9802 0.9916 U2 2.6762.436 2.508 clo 0.42490.4667 0.4534 R 0.37370.4104 0.3987 Fabric Thickness 0.120" 0.146" 0.144"
Fabric Weight 9.20011.150 10.860 (oz/sq. yd.) 10 As the above data reveal, after 10 machine washings the insulating fabric of the invention had increased in thickness approximately 49%. Its thermal resistance had increased approximately 36%. Although the thickness of the comparison thermal fabric had increased approximately 20~, its thermal resistance had increased only 7%.
In Fig. 4, the upper curve, denoted "Test No. 1", illustrate~ empirically the approximate growth in thickness of the insulating fabric of the invention according to the Eastman te~t data.
TEST M0. 2 (Philadelphia College) Fabric A Number of Machine Washing~
U 21.925 14.391 14.17917.659 25 clo 0.295 0.449 0.456 0.366 R 0.046 0.069 0.071 0.057 Fabric Thickness 0.072" 0.082"0.092" 0.101"
Fabric Weight6.770 7.970 7.710 7.350 (oz/sq. yd.) TEST N0. 2 (Philadelphia College) Fabric B Number of Machine Washings ., :, 0 1 5 10 ; U 24.581 25.029 19.257 26.810 clo 0.263 0.258 0.336 0.241 R 0.041 0.040 0.052 0.037 Fabric Thickness 0.091" 0.111" 0.116" 0.072"
Fabric Weight 8.910 10.680 11.360 10.310 ~1 (oz/sq. yd.) ', 3~2~
According to the above data from the Philadelphia College laboratory test, after 5 machine washings the insulating fabric of the invention had increased in thickness by approximately 28~, and its S thermal resistance had increased approximately 54%.
After 5 machine washings, the thickness of the comparison thermal fabric had increased 27~, but its increase in thermal resistance was only 27%.
After 10 washings, both test fabrics exhibited a decline in thermal resistance, but the decline in the compari~on fabric was greater than that in the fabric of the invention. After 10 washings, the thickness of the comparison fabric had reduced drastically, whereas the thickness of the fabric of the invention continued to increase.
In Fig. 4, the lower curve, denoted "Test No. 2", illu~trates empirically the approximate growth in thickne~s of the insulating fabric of the invention according to the Philadelphia College test data.
Notwithstanding the comparison fabrics in the two above te~ts were more than 2 ounces per square yard heavier than the insulating fabrics of the invention, the test data confirmed the superior thermal or heat retention properties of the fabric of the invention.
As indicated previously, the insulating fabric of this invention may include as its base fabric any knitted thermal fabric incorporating air-entrapping ;~ cells. A highly satisfactory insulating fabric embodying this invention may be made utilizing as its base fabric the triple tuck 2 x 2 rib knitted thermal fabric disclosed in Morgan U.S. Patent 2,839,909 aforesaid. Fig. 7 of the drawing depicts the knitting diagram for that fabric, illustrating both the method used in knitting the fabric as well as its stitch structure.
,~
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In Fig. 7, the horizontal letters D, D, C, C, D, etc. denote individual needles mounted 2 x 2 on the dial and on the cylinder, re~pectively, of the knitting machine when Fig. 7 i~ read a~ the method of knitting.
Those letters also depict the 2 x 2 alternating dial and cylinder needle wales in the knitted fabric. The vertical left-hand column of numbers 1, 2, 3, etc.
identifies consecutive yarn feeds of the circular knitting machine used, and also depicts the fabric courses knitted at those yarn feeds. The letters T and K indicate, re~pectively, in the knitting process, whether the cylinder and dial needles tuck or knit.
Those letter~ also identify, respectively, the tuck loops and knitted stitches in the fabric.
The knitting diagram of Fig. 7 illu~trates one complete 8 course cycle of knitting, which is repeated successively on the knitting machine to produce thermal fabric having air-entrapping cells on both sides.
In utilizing that thermal fabric as the base fabric for this invention, a high bulk 100~ acrylic yarn is fed to the needles of the knitting machine at yarn feeds 4, 5, 6, 7, while the polyester/cotton yarn is fed to the needles at yarn feed~ 1, 2, 3 and 8. In ~uch arrangement, at yarn feeds 1, 2 and 3 the polyester/cotton yarn is tucked on the dial needle~ and knitted on the cylinder needle~. At yarn feed 4, where the high bulk acrylic yarn is fed, all needles knit, thus ca~ting the triple tucks of poly/cotton yarn off of the dial needles.
At yarn feeds 5, 6, 7, the acrylic yarn is tucked by the cylinder needles and knitted by the dial needles. At yarn feed 8, where the polyester/cotton yarn is fed, all needles knit so that the triple tuck~
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,.~ "~ . ~, .. .
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of acrylic yarn on the cylinder needles are ca~t off.
As a result, the high bulk acrylic yarn appears on the inside face of the tubular fabric. The combined polyester and cotton yarn appear~ on the outside face of the fabric, and provides the necessary knitted frame or framework for anchoring and stabilizing the acrylic yarn.
Insulating fabric in accordance with Fig. 7 was knit on an 8 feed, 12 cut circular rib knitting machine. The yarns used were DuPont's 22/1 (worsted count) Orlon 44 high bulk acrylic yarn and Eastman's 18/1 Kodel 50/50 polyester/cotton yarn. The fabric, when removed from the knitting machine, weighed approximately 7.5 ounces per square yard. Normally, commercial triple tuck thermal fabric made in accordance with ~organ U.S. Patent 2,839,909 weighs approximately 9 ounces per square yard.
The insulating fabric, knit in accordance with the specifications described above, was subjected to a series of 10 machine washings as a result of which the fabric added bulk and increa~ed in thickness by .046", or approximately 33-1/3%. The original fabric thickness, prior to the first washing was .138". Its thickness after the tenth washing was .184". Set forth below i9 a table illustrating the thickness of the fabric following each of the ten machine washings to which it was subjected:
... .. . .. . .
1~9~
Number ofFabric Thickness Machine WashingsAfter Each Washing original (unwashed).138"
1st washing .166"
2nd washing .170"
3rd washing .172"
4th washing .179"
5th washing .179"
6th washing .184"
7th wa~hing .176"
8th wa~hing .188"
9th washing .166"
10th washing .184"
It will be ob~erved, from the foregoing table, that the knitted fabric continued to increase in thickness through the first ~ix machine wa~hings, following which the thickne~ of the fabric tended to stabilize. As a result of the several wa~hings, and the concomitant increase in thickne~, due to increased bulk or loft, the fabric enhanced its air-entrapping capacity, acquired a greater heat retention quality and thus became a warmer fabric than it was before it was ; washed.
Fig. 8 of the drawing depicts the knitting diagram for a modified weft knit insulating fabric made in accordance with thi~ invention. The fabric is made on a circular 2 x 1 rib knitting machine in which pairs of independent type cylinder needle~ alternate around the needle circle with single, independent type dial needles. Preferably, the machine ha~ eight yarn feed~, or multiple~ thereof. Fig. 8 illustrates both the method used in knitting the modified insulating fabric a~ well a~ its stitch structure.
... .
In Fig. 8, the horizontal letters C, C represent the pairs of cylinder needles which alternate with the single dial needle~ D for carrying out 2 x 1 rib knitting on the machine. Those letters also depict the S 2 x 1 alternating sequence of the cylinder and dial needle wales in the knitted fabric. The vertical left-hand column of numbers 1, 2, 3, etc. identifies the consecutive yarn feeds of the knitting machine and, also, indicates the fabric cour~es knitted at those yarn feeds. The letters K and T indicate, respectively, in the knitting process whether the needles knit or tuck. It will be observed from Fig. 8 that the alternating pairs of cylinder needles C always knit yarn, whereas the intervening ~ingle dial needles D tuck yarn at alternating yarn feeds and knit yarn at the intervening yarn feeds. The letters K, 'r also identify~ respectively, the knitted stitches and the tuck loops in the fabric.
The knitting diagram of Fig. 8 illustrates one complete eight cour~e cycle of knitting, which is repeated successively on the multi-feed circular 2 x 1 rib knitting machine utilized.
Preferably, a polyester/cotton yarn is fed to the knitting machine needles at yarn feeds 1, 3, 5 and 7, while a 100% acrylic bulk yarn is fed to the needles at yarn feeds 2, 4, 6 and 8. The dial needles are tucked at yarn feeds 1, 3, 5 and 7, thereby forming tuck loops of the poIyester/cotton yarn in spaced courses and ~paced wale~ of the fabric. Neither the dial nor the cylinder needles are tucked at yarn feeds 2, 4, 6 and 8.
In the fabric of Fig. 8, the acrylic bulk yarn appears on the inside face of the tubular fabric, while " .
lZ9~49~
the combined polyester and cotton yarn appears on the outside face. The polyester/cotton provides the necessary knitted framework for anchoring and stabilizing the acrylic yarn in the fabric.
The outer, polyester/cotton yarn face of the fabric presents the usual 2 x 1 rib construction, in which wale-wise extending valleys one wale wide, knit by the dial needles D, alternate with wale-wise extending ribs two wales wide, knit by the cylinder needles C. The tuck loops formed from the polyester/cotton yarn by the dial needles D are disposed in spaced relation in the valleys on the outside of the fabric, thereby creating, in those valleys, a succes~ion of small, wale-wise extending lS air-entrapping cells on the outer face of the fabric.
The tuck loops constitute the top and bottom walls of the cells, and the adjacent rib~ constitute the side wall~ thereof. The floor of each cell, di~po~ed intermediate its spaced side, top and bottom walls, is constituted by the fabric of the valley. To ensure that the air-entrapping cells formed on the outside of the fabric have a three dimensional character, the yarns are fed to the needles of the knitting machine under relatively heavy tension to produce a tight knit fabric.
The inner face of the fabric has valleys two wales wide, formed by the cylinder needles C. The~e valleys are separated by wale-wise extending ribs one wale wide, knit by the dial needles D. Because the fabric is tight knit, the inside valleys are relatively deep, and are covered or overlaid by fibers of the acrylic bulk yarn. As a result, the inner valleys have an enhanced air-entrapping capacity and function as ':`
:
.
lZ9~4~
elongated, continuous air-entrapping cells, thereby increasing the insulating character of the fabric.
In knitting a relatively heavy weight insulating fabric in accordance with the modification of Fig. 8, a 10 cut circular rib knitting machine preferably is used. The yarns may be of the character previously referred to such as, for example, DuPont's 22/1 (worsted count) Orlon 44 high bulk acrylic yarn and Eastman's 12/1 Kodel 50/50 polyester/cotton yarn.
However, the modification depicted in Fig. 8 also may be utilized, in the practice of this invention, for knitting a relatively lightweight insulating fabric.
For example, the fabric can be knit on a 14 cut circular rib knitting machine utilizing medium weight yarns such as, for example, DuPont's 32/1 (worsted count) Orlon 75 bulk acrylic yarn and Eastman's 28/1 Kodel 50/50 polyester/cotton yarn.
Following knitting, the fabric preferably is subjected to the several finishing operations depicted schematically in Fig. 3, including a light napping of the inner, acrylic face of the fabric. However, in order to ensure proper width and shrinkage control of the finished lightweight fabric, it is preferred that the tubular fabric be knit of a diameter one inch less than the width at which the fabric is calendered on the tensionless calender. For example, if the fabric of Fig. 8 is knit on a body-size knitting machine having a 13" diameter needle cylinder, it is preferred that the tubular fabric be finished at a width of 14" on the tensionless calender. In the same vein, fabric knit on a machine having a 16" diameter needle cylinder should be finished by calendering to a tubular width of 17".
The finished fabric, following its removal from the ~' ., .
tensionless calender, should be of a relatively tight construction, on the order of 32 to 34 courses per inch. The weight of the finished fabric should be on the order of 4.25 to 4.40 ounces per square yard.
Lightweight insulating fabric of the type depicted in Fig. 8, knit in accordance with the foregoing machine, yarn and finishing specifications, embodies all of the new, important, surprising and desirable characteristics of this invention, including fabric stability, increased warmth despite its relatively light weight, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and the inherent capacity, upon repeated washings, to increase substantially in bulk, thickness and warmth.
A sample of the lightweight insulating fabric of Fig. 8, knit in accordance with the specifications described above~ was subjected to a series of ten machine washings. Following the ten washings, the fabric wa~ found to have increased in thickness by 40%, while its weight in ounces per square yard had increa~ed a mere 8%.
The shrinkage characteristics of the fabric also were impre~sive. After the ten washings, the fabric exhibited length-wise shrinkage of a mere 2%. After the first machine washing, the fabric shrank width-wise about 13%, but thereafter width-wise shrinkage stabilized.
Although preferred embodiments of this invention have been shown and described for the purpose of illustration, it is to be understood that variou~
changes and modifications may be made therein without departing from the spirit and utility of thi~
invention, or the scope thereof as set forth in the appended claims.
!
,~
~;~5~9I3 For example, yarns equivalent to the bulk acrylic and blended polyester/cotton yarns described above could be used in the successful practice of this invention. The bulk yarn may be other than acrylic, but alternate bulk yarns should provide properties of low absorbency, warmth, resilience and comfort comparable to high bulk acrylic yarn, as well a~ the capacity to be napped. The non-bulk yarn preferably should be composed partly of cotton, because of its inherent good hand and absorbency. While polyester is the preferred fiber to be blended with cotton in the non-bulk yarn, other synthetic fibers could be used in lieu thereof, provided the combination synthetic/cotton yarn provides the necessary characteristics of absorbency, quick drying, good hand and ~trength. The synthetic/cotton yarn selected must function to provide a relatively rigid knitted framework for anchoring and stabilizing the bulk yarn in the fabric.
Of course, a reasonable range of the knitting specifications utilized is permissible in the practice of the invention, depending on the desired weight of the finished fabric. For example, in knitting lightweight insulating fabric of the 2 x l rib type depicted in Fig. 8, use of polyester/cotton yarns within the range of 24/l to 28/l is well within the scope of the invention. Likewise, again depending on the desired weight of the finished fabric, the courses per inch of the fabric, following calendering, may range from 30 to 36 without impairment of the several advantages which characterize the invention.
Napping of the inner acrylic side of the fabric, of course, increases the insulation effect of the fabric. However, napping is not critical to the ., .
~954~
achievement of the advantages of the invention, and may be dispensed with, if desired. Fabrics incorporating the invention which have not been napped also exhibit the advantages of fabric stability, relative light weight with increased warmth, enhanced absorbency, increased resistance to shrinkage, enhanced comfort and the capacity, upon repeated washings, to increase in bulk, thickness and warmth. The fabrics of the invention which have not been napped, upon repeated washings, steadily increase in bulk, but at a slower rate than the fabrics which have been napped.
Claims (22)
1. An insulating fabric having an inner fabric face of soft texture formed of a bulk yarn and an outer fabric face formed of a combined synthetic and cotton yarn, said insulating fabric being characterized by an increase in thickness as the result of plural washings to enhance its heat insulating quality and comprising (a) a base fabric constituted of a knitted thermal fabric having air-entrapping cells, (b) said base fabric being knitted of a bulk yarn in selected courses and being knitted of a combined synthetic and cotton yarn in courses intervening between the selected courses, (c) the combined synthetic and cotton yarn forming a knitted framework for anchoring and stabilizing the bulk yarn in the fabric.
2. The insulating fabric of Claim 1, wherein the bulk yarn is a high bulk acrylic yarn and the combined synthetic and cotton yarn is a polyester/cotton yarn.
3. The insulating fabric of Claim 1, wherein the base fabric comprises a 2 x 1 rib knitted fabric and the combined synthetic and cotton yarn is formed into tuck loops in spaced courses and spaced wales of the fabric.
4. An insulating fabric of Claim 1, wherein the bulk yarn is napped.
5. An insulating fabric having an inner side and an outer side comprising (a) a base fabric constituted of a knitted thermal fabric having air-entrapping cells, (b) said base fabric being knitted of a bulk acrylic yarn in selected courses and being knitted of a combined polyester and cotton yarn in courses intervening between the selected courses, (c) the acrylic yarn being disposed on the inner side of the fabric and the combined polyester and cotton yarn being disposed on the outer side of the fabric.
6. The insulating fabric of Claim 5, wherein the acrylic yarn is napped.
7. The insulating fabric of Claim 5, wherein the base fabric comprises a 2 x 1 rib knitted fabric and the combined synthetic and cotton yarn is formed into tuck loops in spaced courses and spaced wales on the outer side of the fabric.
8. The insulating fabric of Claim 5, wherein the combined polyester and cotton yarn provides a knitted framework for anchoring and stabilizing the high bulk acrylic yarn in the fabric.
9. An insulating fabric having an inner side and an outer side comprising (a) a base fabric constituted of a knitted fabric having air-entrapping cells, (b) said base fabric being knitted of a bulk yarn in alternating courses and being knitted of a combined synthetic and cotton yarn in courses intervening between the alternating courses, (c) the bulk yarn being disposed on the inner side of the fabric and the combined synthetic and cotton yarn being disposed on the outer side of the fabric.
10. The insulating fabric of Claim 9, wherein the base fabric comprises a 2 x 1 rib knitted fabric and the combined synthetic and cotton yarn is formed into tuck loops in spaced courses and spaced wales on the outer side of the fabric.
11. The insulating fabric of Claim 9, wherein the bulk yarn is acrylic yarn and the combined synthetic and cotton yarn is a polyester/cotton yarn, and provides a knitted framework for anchoring and stabilizing the acrylic bulk yarn in the fabric.
12. The insulating fabric of Claim 11, wherein the acrylic yarn is a high bulk yarn.
13. A method of making an insulating fabric having an inner fabric face of soft texture formed of a bulk yarn and an outer fabric face formed of a combined synthetic and cotton yarn comprising knitting a base fabric having air-entrapping cells and, during knitting, (a) forming selected courses of the base fabric of a bulk yarn and forming courses intervening between the selected courses of a combined synthetic and cotton yarn and (b) feeding the yarns selectively to place the bulk yarn on the inner fabric face and to provide a knitted framework composed of the synthetic and cotton yarn on the outer fabric face for anchoring and stabilizing the bulk yarn in the fabric.
14. The method of making an insulating fabric of Claim 13, further including the step of napping the bulk yarn following knitting of the base thermal fabric.
15. The method of making an insulating fabric of Claim 13, further including the step of subjecting the fabric to plural washings to increase its thickness and enhance its heat insulating quality.
16. The method of making an insulating fabric of Claim 13, further including the step of increasing the heat insulating quality of the fabric by at least 25%
by subjecting the fabric to plural washings to increase its thickness.
by subjecting the fabric to plural washings to increase its thickness.
17. The method of making an insulating fabric of Claim 13, further including the step of increasing the thickness of the fabric to enhance its heat retention quality by subjecting the fabric to a plurality of washings.
18. The method of making an insulating fabric of Claim 13, further including the step of subjecting the fabric to a plurality of washings to increase its thickness by at least 33-1/3% to enhance its heat retention quality.
19. The method of making an insulating fabric of Claim 13, further including the steps of (a) forming the selected courses of a bulk acrylic yarn and (b) forming the intervening courses of a combined polyester/cotton yarn.
20. The method of making an insulating fabric of Claim 13, further including the steps of (a) forming alternating courses of the base fabric of an acrylic bulk yarn and (b) forming the courses intervening between the alternating courses of a combined polyester/cotton yarn.
21. The method of making an insulating fabric of Claim 13, wherein the base fabric is a thermal fabric.
22. The method of making an insulating fabric of Claim 13, further including the steps of (a) knitting a 2 x 1 rib base fabric and (b) forming the synthetic and cotton yarn into tuck loops in spaced courses and spaced wales on the outer fabric face.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000541086A CA1295490C (en) | 1987-07-02 | 1987-07-02 | Insulating fabric and method of manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000541086A CA1295490C (en) | 1987-07-02 | 1987-07-02 | Insulating fabric and method of manufacture thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1295490C true CA1295490C (en) | 1992-02-11 |
Family
ID=4136015
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000541086A Expired - Lifetime CA1295490C (en) | 1987-07-02 | 1987-07-02 | Insulating fabric and method of manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1295490C (en) |
-
1987
- 1987-07-02 CA CA000541086A patent/CA1295490C/en not_active Expired - Lifetime
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