US 3305911 A
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Description (OCR text may contain errors)
Feb. 28, 1967 R. CHAPMAN ETAL FABRI CS Filed Aug.
l wo F Fig. 4l.A
d I I /A/VEA/TO/ ATTORNEYS United States Patent Otce n 3,305,9 Patented Feb. 28, 19
3,305,911 FABRICS Roy Chapman and John DArcy Henry Hall, Harrogate, England, assignors to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain Filed Aug. 5, 1963, Ser. No. 299378 Claims priority, application Great Britain, Aug. 30, 1962, 33,382/ 62 7 Claims. (Cl. 28-72) This invention relates to fabrics having .an open mesh construction.
We have made the observation that useful fabrics having an open mesh construction can be made by knitting or weaving a fabric from an as-spun synthetic filament yarn capable of being elongated -followed by drawing the fabric in at least one direction in the plane of the fabric.
When drawing the fabrics of most but not all constructions, the filament yarns become drawn, i.e. irreversibly elongated, in the regions between their intersections to a greater extent than that at their crossover regions. This becomes apparent when the drawn fabric is dyed, since it then has dye flecks of darker colour at the crossover regions of the yarns. However these regions should be suiciently strong not to affect adversely the mechanical properties of the fabric.
According to the present invention, therefore, a process for making a fabric having an open mesh construction comprises knitting or weaving a fabric fromv synthetic yarn capable of being irreversibly elongated at least 1.75 times its length, and drawing the knitted or woven fabric uniformly over substantially the whole area of the fabric at least 1.75 times in at least one direction. If desired, the fabric may also be drawn at least 1.75 times in another direction, preferably at right angles to the first draw-` ing direction.
Undrawn or partially drawn yarn may be used in the invention. In the case of polyethylene terephthalate yarn, a birefringence in the range of 2 103 to 20X 10-3 preferably 12X 10-3 to 16 103 is suitable. Such a yarn is capable of being elongated 2-6 times its length.
In the case of polypropylene yarn this should be capable of being elongated at least 1.75 and up to 9 times its length. Suitable polypropylene yarns have a birefringence of l 10n3 to 30 103 and preferably between 10 103 and 20X 10-3.
In the case of polyethylene terephthalate yarn draw ratios of 2.0 to 4.5 times are suitable. Suitable temperatures for drawing the fabric are above the 2nd order transition temperature.
The fabric may be drawn between pairs of rolls, rotating at suitable speeds to give the desired draw ratio in the fabric in the longitudinal direction. For drawing in the transverse direction the fabric may be gripped at the edges by clips which can be made to separate by a given amount corresponding to the desired draw ratio. We have found that equipment used for biaxially orienting film may be used for drawing our fabric.
The fabrics are useful for industrial applications e.g.
as reinforcements for laminates, as laundry bags andv shnets as well as for domestic textile applications, such as net curtains.
If, during the drawing of a fabric made from polyethylene terephthalate, temperatures substantially below the second order transition are used, fabrics having high shrinkage can be made. It will be appreciated that in this context the yarns can be madeito shrink by the application of heat so that at least some of the elongation imparted during drawing is lost. In this connecti the rate of drawing is also of importance, since the w1 done in drawing, generates heat. Under very high rz of drawing, and in the absence of forced cooling, hea generated under virtually adiabatic conditions. W lower rates of drawing, and with forced cooling, the drz ing process can be made to function under almost i thermal conditions, e.g. at room temperature. For cc ing, draughts of cold air or liquids e.g. water may used. After drawing the fabrics may be subjected heat-setting to impart dimensional stability, and genera improved fabric appearance.
One suitable form of apparatus comprises means forward drawing and sideways drawing the fabric w means for heat setting the `fabric on a stenter before is wound up. The forward drawing means compri hot nip rollers which may be heated by hot water c to about 85 C. and cold nip rollers. The draw point located between the two sets of nip rollers beneath infra red heater. The draw ratio is determined by i relative speeds of the cold and hot nip rolls. The f` ward drawn fabric is fed from the cold nip rolls intc sideways draw stenter where it is held by self-grippi clips with means for controlling the temperature for l ample between and 100 C. Following this sidewz draw stenter is a second and larger part where the fab is heat set and which is provided with means for movi the fabric and heating it to temperatures up to ab( 240 C. Means are provided for cooling the fabric forced air before it is wound up on a beam which driven from the fabric forwarding means on the sten` by an arrangement adapted to compensate for the bui up of fabric on the beam.
Evenly drawn fabrics can be obtained by this successi drawing technique, first length-wise and then in wid The fabric is preferably provided with selvedges to fac itate gripping for drawing in width.
A preferred embodiment of the invention will now described by way of example with reference to the companying drawings which are photographic represen tions on a reduced scale of fabric samples and in whic FIG. l shows a sample warp-knitted from undra polyethylene terephthalate yarn,
FIG. 2 shows a similar sample as shown in FIG. after drawing 3.5 times in length only,
FIG. 3 shows a similar sample as shown in FIG. after drawing 3.5 times in width only, and
FIG. 4 shows a similar sample as shown in FIG. after drawing 3.5 -times in bot-h length and width.
Referring to FIG. l, the fabric has been knitted fr( 80 denier yarn on a 28 gauge high speed warp-knitti machine to 60 courses per inch, using a marquisette cc struction. y
After drawing the fabric to 3.5 times in length on a pattern effect is obtained as shown in FIG. 2. Drawi the fabric in width, but not in length results in a patte as shown in FIG. 3.
Because of the different drawing effected in one djr tion, not only a different pattern effect is obtained, l: on dyeing such fabrics a multi-tone suc-h as a two to effect may be obtained from a single dye bath. Su fabrics find application as curtain nets.
Referring'to FIG.A 4, a fabric with a Wide open me is obtained after'drawing the fabric, as shown in FIG. to 3.5 times its length followed by drawing to 3.5 tim its width. Such fabrics are sheer, light in weight a1 suitable for reinforcement in coated or laminated stru tures.
Example 1 Warp knitted reverse locknit fabric was knitted from denier undrawn polyester yarn of birefringence Useful fabrics were obtained, which on examination showed that:
(1) Heat setting at 200 C. at 25 ft./min. does not noticeably weaken any of the above structure knitted from 15x10-3 birefringence yarn, although some weakening was observed in the case of a similar fabric knitted from undrawn yarn of 8X10-3.
(2) In the above examples 5, 6 `and 7 were more evenly drawn (along the individual filaments) than 2, 3 and 4. This is a direct consequence of knitting construction. In all cases however the overall effect is one of extreme regularity of drawing.
What we claim is:
1. A process for making knitted and woven fabrics [0 3- The yafn el'ystellitlty WaS S0 Small that there 15 having an open mesh construction over substantially the n0 appreciable embflttlement The fbfle WHS OT- entire area of the fabric comprising making the fabric d'dfaWH 1H length by a taeter 0f 3-0 `21h85" 'C' Utd from undrawn synthetic yarn capable of being irreversibly equently CODtlHUOllSlY Sideways-drawn 111 Width 1H elongated at least 1.75 times its length, said yarn being plane of the fabric by a factor of 4 .2 at 100 C. selected from the group consisting of polyethylene ter- 1 tige Same COIltHll'lOllS PfOeeSS the fabfle WHS heat Set 20 ephthalate and polypropylene; and uniformly drawing the 00. C- before "bhelttg Wollnd UP et a Speed 0f 75 feet fabric at a temperature above the second order transition mmute- The 11119211 W1d-th Of the fa'brlcs was .16" temperature in at least one direction uniformly over subth nal W1dth 48 It W111be 110t1ed that the wldth stantially the whole arca cf thc fabric in the plane of the ot increased by the factor of the sideways draw ratio fabric at least 1 75 time3- 111s@ C011tra 1t1011 Occurs in the forward-drawing stage, 25 2. A process as in claim 1 wherein the fabric is also iely` from 16 to about 12". The drawn denier is drawn at least 1.75 times in a second direction. VOXlmetely 25 Speeds 0f UP t0 300 feet Per mlDUte 3. A process as in claim 2 wherein the two directions be use@ The mesh Obtaltled by thlS USe Of the Presin which the fabric is drawn are at right angles to each invention is considerably larger than could be ob- Otihe edvby conventional knitting of such a tine denier yarn. 30 4 A process as in Claim 1 including the Step of sub. Example 2 jecting the drawn fabric to a heat setting operation to i) A warp knitted reverse locknit fabric, having patgggnsmnal Stablhty and generally Improved fabnc tdjtaftlon alSZfSOHW'S: bad 1.0/23 from 1'2/1'0" was 5. A process as in claim 1 wherein the undrawn yarn rom emer u1? ralf/n polyethylene tefeph 35 is polyethylene terepht'halate having a birefringence in the ate polyester yarn of b irefringence 15 X104. The range 2X10-s to 20X10-3 '.1560 vasarwd dra m letlgth by a facto? Of3'0 6. A process as in claim 5 including the step of subhe 1me ofS thselten ybcontnuously drawn in woidth jecting the drawn fabric to a heat setting operation to h p e UC y a ,actor "if 3'0 at 130 C- impart dimensional stability and generally improved fabric ne same continuous process the fabric was 'heat set at 40 appearance. .hec'fullflgeflliyoufg .up at 25 mm' 7. A process as in claim 1 including the step of dyeing ns and conditions in n/Iree 2 nged tlslfng ge the drawn fabric whereby multi-tone eifects are given by Owing data: CCP or e a single dyebath.
P tt t f T iXallple/FabT10 a em no anon Longitudinal giggling), Transverse dgiiug draw factor C. d i'aw factor C. Beek Front d .o/sA 'g 18 8 o i/in. 25 75 2.5 115 Nerjjiiiji: 0i@/iii/o:@irrita/ritirati: iIiZ/'L/J'): T i? 33 iig References Cited by the Examiner UNITED STATES PATENTS 2,475,588 7/1949 Bierman. 2,591,566 4/1952 Livingston 28-72 3,055,048 9/1962 Koppehele 26--57 X 3,140,330 7/1964 Guricrcz 264-288 3,176,374 4/1965 Murray et al. 28-72 3,184,820 5/1965 Kanbar 28-71.3 3,207,654 9/1965 Reilly 57-14'0 X FOREIGN PATENTS 610,171 10/1948 Great Britain. 515,199 8/1955 Canada. 86,725 1/1956 Norway. 590,313 1/1960 Canada. 1,250,397 11/1960 France.
247,889 12/1960 Australia. 100,070 12/1961 Netherlands.
MERVIN STEIN, Primary Examiner.
DONALD W. PARKER, I. KEE CHI,