CA1234968A - Heavy-weight nonwoven fabric of hydraulically- entangled fibers - Google Patents

Abstract

TITLE
Heavy-Weight Nonwoven Fabric of Hydraulically-Entangled Fibers ABSTRACT
An improved process is provided for preparing a strong, heavy-weight, nonapertured nonwoven fabric of hydraulically entangled staple fibers of synthetic organic polymer. A heavy-weight batt of fibers, immediately after having been wetted, is treated by a row of hydraulic jets which drives portions of fibers from one surface of the batt to the other.

Description

TITLE
~eavy-Weight Nonwoven Fabric of Hydraulically-Entangled Fibers ACK~RO~ND OF THE INVENTION
Field of the Invention _ This invention relates to n~n~pertured, heavy-weight nonwoYen fabric made from hydraulically entangled staple fiber~ of synthetic organic p~lymer.
~ore particularly, the inven ion concerns such a fabric having unusually strong tensile characteri~$ics and high resistance to disentanglement.
~L~
N~nwoven fabrics, in which hydraulicatly entangled ~taple fibers of synthetic organic polymer ~rm a stable, nvnapertured fabric without th~ pre3~nce of resin binder of fiber-t~-fiber melt bond3 are known in he art. Such ~abric~ have been manufactured commercially with unit welght3 th~t are usually less than 4 oz~yd2 [136 g/m~3. Bunting et al, U.S. Paten~s 3,493,462, 3,508,308 and 3,560,326 disclose a wide ~ariety o ~uch fabxics with unit weights a high as about 20 oz~yd2 ~680 g/m2~. ~he commeroially manu- .
~actured nonapertured ~abrics of hydraulieally entangled ataple fiber~ are strong and ~xhibit ~trip tensile ~trengthY of a~ high as about 8.5 ~lb/ln1~oz~yd~
[0.44 (N/cm3~9/m~)~. However, the heavy-weight fabrics of th B t~pe which were di6clos~d by Bunting et ~1 were relatively weak. For exampleg 6uch heavy-weight fabric6 had ~trip tensile ~trengths of 4.39 ~lb/i~)~toz~yd2) 10.226 (N/cm)/g/m23] a~ a weiyht of ~-7 Z/Y~ 1227 g~m ~ and 1.3 and 1.1 ~lb~in3/
(oz~yd2) ~0~067 and 0.~59 ~N/cm)/tg/m2)1 ~or weights of 10 and 20 oz~yd2 ~339 and ~78 g~m~J, xespectively.
~o ~trengthen these hydraulically entangled staple fiber nonwoven fabrics, variou~ approache~ have been ,. ~
-r~

made. ~hese included incorporatin~ in the ~abrics very long ~e.g. 7 6 inch ~15.24 cm~) ~ibers, ~ibers of special cro~s-section, 6ub~tantially continuous filaments, scrims, layers of continuous filament webs, or ~pecially designed layers. Process modifications intended to provide thc increase in strength included treating the ~taple fiber starting web with hydraulic jets fir~t with the web moving in one direction and then with the web moving in a direction perpendicular to the first direction, adding ~pecial chemical agents to the hydraulic jets, utilizing ~peeial supports or grills on which the webs were hydraulically ~reated, and ~tarting with special yarn~. Generally, each ~f these 6trength increasing modifications were useful for lighter weight fabrics. ~owever, these modifica-~ions generally were not sati~actoxy for preparing ~trong, heavy weight, nonapertured nonwovPn fabrics, which consi~ted essentially of hydraulically entangled staple fibers of ~ynthetic ~rganic polymer. Such strong, h avy-weight ~abrics are desired in useR such as heavy-duty gas filtration. ~he purpose of thi~
invention i~ to provide ~uch a strong nonapertured, heavy-weight nonwoven fabric.
SUMMARY OF THE INVENTION
The present invention provides an improved heavy-weight, nonapertured nonwsven fabric which I consi~ts essentially of hydraulically entangl~d staple : fibers of synthetic organic polymer. The improvement comprises the ~abric having in combination a unit weight ! 30 in the range of 200 to 850 g/m2 ~6- 5 oz/yd2], a grab strength of at least 16D N/~m 191 lb~in], a ~trip tensile strength of at least 0.26 (n~cm)/(g/m~
~5 (1~/in~(oz~yd2~] and a resistance to di~en~angle-ment of at least 50 alternate extension ~yele~.
Preferably, the fabric combines a unit weight in ~he ~L~3~
range of 240 to 510 g~m2 [7-15 oz/yd2], a grab strength in the range of 245 to 875 N/cm [140-500 lb/in~, a strip tensile strength in the range vf 0.36 to 0.77 (N/cm)/~g/m2) 17-15 (lb/in)~oz/yd )] and a resistance ~o distenglement of at least 90 alternate extension cycles. Usually, the preferred ~abrics have 3 t~ 10 jet tracks per centimeter 17.5-25 per inch~. Th~
preferred ~taple fibers are of 1 to 18 dtex [0.9-16 den] and of 0.6 to 5 cm 11/4 to 2 inch~ length, Preferred polymers for the fitaple ~ibers are poly-(~-phenylPne terephthalamide), poly(m~phenyl~ne isophthala~ide) or poly(ethylene terephthalate).
BRIEF DESCRIPTION OF THE DRAWING
' The invention will be understood more readily by reference to the drawing which is a graph of s~rip tensile strength versus unit weight that compares the fabrics of the present invention with those o~ he prior art.
DETAILED DESCRIPTION O~ PP~EFERRED E:MBODIMENTS
A~ u~ed her~in, the term Nheavy-weight" means a nonapertured nonwoven fa~ric of hydraulically entangled ~taple fibers that has a unit weight in ~he range of 200 ~o B50 g/m2 [6-25 oz~yd2]~
The key advantageous ~istinction of the products of the present invention is illustrated in the graph of the attached drawing. The shaded area represents the nonapertured nsnwoven fabrics o~
hydraulically entangled staple fibers of the prior , art. The individual points ~hown on the graph ! 30 xepresent the strip tensile data given in detail hereinafter in the Examples. Note the extraordinarily higher tensile ~trengths of the hea~y-weight fabrics of the invention. These strong ~abrics of the inventio~
also possess excellent grab strengths and rPsistance to disentanglement.

~ 3~
Generally the staple fibers which are suitable ~or use in the nonapertured nonwoven abrics of the present inve~tion are in the range ~f 1 to 18 dtex [0.9 ~o 16 denierJ and in the range of 0.5 to 5 cm [lf4-2 inches]l~ng. Preferably, the dtex ranye is 1.4 to 2.5 dtex 11.25-2.25 denier3 and the length range 1.3 to 3.~ cm [1~2 ~ 2 inches]. Fibers of circular cross-section are preferredO
The ~taple fibers may be of any synthetic organic polymer. Preferred p~lymers include poly(~-phenylene terephthalamide), poly(m-phenylene isophthalamide) and poly~ethylene terephthalat2~.
Fabrics made of hydraulically entangled fibers of each of the polymers are illustrated in the Examples.
The heavy-weight nonaper$ured nonwovPn fabric of the present invention pos~esses a unique advantageous combination of charactaristics, whi~h includes a grab strength of at least 160 N/cm 191 lb/in], preerably in the range of 2~5 to 875 N/cm 1140 to 500 lb~inJ, a strip ~ensile ~trength ~ at least 0.2S
(N~cm)~(g/m~) 15 lb~in)/(~z/yd2)~, preferably in ~he range o~ 0.36 to 0.77 (N~cm)/~g/m2) [7-15 llb~in)/
oz~yd2~ and the r~sistance to di~en~anglement i~ at ¦ least 50 alternate extension ~ycles~ preferably at ~5 least 30 cycle~.
¦ The pxeferred mann~r in which the hydraulic I entanglement treatment is per~ormed in manufacturing the preferred ~abrics of the present invention xesult~ in the nonapertured fabrics having a r peating pattern of close.ly spaced lines of fiber entanglement, ! called ~jet traeks." The jet track5 are readily visible under low magnification. The preferred fabrics ! of the invention have between 3 and ~0 jet track~ per cm [~.5 to 25 per inchJ and most preferably between 3 and 6 jet track6 per cm [7.5 to 15 per inch~.

In making the nonapertured n~nwoven fabrics of the present invention, the ~taple fibers are formed into ~tarting ba~ts of ~00 to 850 g/m [~ to 25 oz/yd ]
by known ~echniques which employ Rando-webbers or air-5 laydown equipment such as that di~closed in Zafiroglu, U.S. Patent 3,797,074. ~ continuous hydraulic entanglPment treatment is then performed with the staple-iber ~tarting batt in place sn a ~oraminous support, such as a woven wire screen.
In the hydraulic Pntanglement treatment, the batt is exposed to a series of fine, columnar stream of water ~upplied to one surf~ce of the batt and then to the othex ~urface of the batt. The streams Qf water are supplied ~rom a row of orifices located a short distance, usually about 2.5 cm ~1 inchl ab3ve the ~urface o~ the batt. Orifices of the type disclosed in Dworjanyn, U.3;. Patent 3,403,862, are employed.
Preferred orifices ha~e a diame~er in the range o~
0.13 to 0.22 mm 10.005 to 0.009 inch]. In the preferred process of the pre~ent invention the orifices are spaced to produce at least 3 jet track~ per cm 17.5 per lnch] and no more than 10 jet tracks per cm [25 per ~nch], and most preferably no more than 5 jet trac~s per c:m [12 . 7 per ir~ch] .
In the preferred hydraulic treatment portion~ o the staple fibers initially located at one ~ur~ace of the batt are driven by the water jet~
through the.thickness o the batt ! t~ the vppo~ite sur~ac~ of the ~att~ ~his important rearrangement of 30 the fibers .i~ perfo:rmed isssrlediately af er ani initial wetting.and preliminary light c~nsolidation o'the batt. If the starting b~tt has BU~fiCient coherency ~ as supplied.to the entanglement ;~tep t the ~very ~ ~irs~
row of water streams can perrorm this important reaxranyement, i~ suppli~d at 5uf~icien~ pressure and if they impact the batt with sufficient forc~. The use of such jets on wide spacings (i.e., no more than 10/cm) results in deeper penetration of the streams into the batt with less interference from adjacent streams than would be obtained with closer spaced jets.
Furthermore, it is preferred that, in contrast to the commonly used commercial practice of gradually increasing the supply pressures of the streams in each successive row of jets, the highest pressures be supplied to the first row of jets (or the first row after the initial wetting operation). Preferably, the pressure to this first row of jets is in the xange of 6890 kPa to 22740 kPa [1000-3300 psi]. This prevents the fibers at the surface of the batt from immediately forming a dense, tiyhtly entangled surace layer, which then resists water-jet penetration and does not allow portions of fibers from one surface of the ~att to be forced through the thickness of the batt to the opposite surface. Once the initial desired rearrange-ment has been performed9 th~ remainder of theentanglement process can be performed in the known manner. Even if closer spaced jets are used in the remaining portion of the hydraulic entanglement procedure, the jet tracks produced by the initial high impact jets are not erased or obscured. The pre-ferred hydraulic~jet trea~ment just described in comparison to the other methods illustrated herein is believed to result in stronger, better entangled and more delamination-resistant heavy-weight nonwoven fabrics.
Staple fiber blends of mixed lengths an~/or mixed decitex usually are more readily made in~o fabrics of the invention than fibers of s~bstantially only one length and decitex. Thus, blends of staple fibers may be formed into fa~rics of the invention with less total expenditure of energy per unit weiyht of fabric, with ~3~
les~ tQtal energy impact product, and with lower maximum j~t pressures. ~eavier, longer and stiffer fibers are more difficult to reArrangc and entan~lc.
~he following test procedures were used to measure the various characteristics and properties reported herein. All measuremen s were made on dry fabrics or fiber.
Tensile properties ar measured on an Instron tester at 70F and 65~ relative humidity.
Strip tensile trength i6 measured in general accordance with ASTM Method D~828-60 on a 1/2 inch [1.27 cm] wide by 4 inch ~10~1~ cm~ long sample, using a 2 inch [5O08 cm~ yauge length and an elongation rate of 50% per minute.
Grab ~trength is measured in general accordance with ASTM Method D-1~82~64, on a 4 inch [10.16 cm~ wide by 6 inch [15.24 cm] long ~ample, u6ing a 3 inch 17.62 cm~ gauge length and an elongation rate of 25~ per minute.
For each of the tensile measurements, samples were cut in the machin~ direction (MD~ and the cross-machine direction (XD) of the fabric. In the graph of the attached drawing, only the averages of MD and XD
value~ are plotted.
Di~entanglement resistance of nonapertured nonwoven fabric was measllred in cycles by the Alternate Exten~ion Te~t described by Johns ~ Auspos, "The ' Measurement of the Resistance to Disentanglement of ¦ Spunlaced Fabrics~" Symposium Papers, Tech~ical~
Symposium, Nonwovens Technolo~y -- Its Impact on the 80~, INDA, New Orleans, Louisiana, 158-lÇ2 (March 1979). The load applied to the t~st sample in the machine direction of the ~abric ~i.e., he vertical load on the tester) in grams was the unit weight in g/m2 multiplied ~y 2~95. The load appliPd 3~

i~ the cross-machine direction was one-half that applied in the machine direction~
In the examples which follow batts o~
staple fibers are given a hydraulic jet treatment to form strong, heavy-weight fabrics of the invention.
Different sets of orifices are employed to provide columnar streams of water ~o the batts, while ~he batts are supported on screens, under which means are provided for removing the water. The orifices are arranged in rows perpendicular to the direction of batt travel and are located about 1 inch (2.5 cm) from the surface of the batt. Five sets of orifices and five different screens are employed. These oriice sets are described as follows:
15OrificeOrifice Diameter Number per Set inch [m~] lnch [cm]
A 0.007 ~0.178] 5 [2.0]
B 0.007 ~0.1783 10 [3.9]
C 0.007 ~0.1783 20 [7.9]
20 D 0.005 [0.127] 40 [15.7]
E 0.005 [0.127] 20 [7.9]
Note that in orifice set A, B, C and E, all the orifices are located in a single row, but in set D the orifises are arranged in two staggered rows spaced 0.04 inch [0.10 cm] apart with Pach row containing 20 orifices/
inch 17.9/cm].
The different wire mesh support screens that are employed in the exampl~s are described as follows:
30ScreenWires per inch [cm] % Open Area A100 x 96 ¦39.3 x 37.8~ 21 B 75 x 58 [29.5 x 22~8] 21 C 40 x 3~ ~15.7 x 14.2] ~6 D 20 x 20 ~7.9 x 7.9~ 41 35 E 50 x 5n [19.7 x 19.7] ~o ~ 9 _ ~ hi~ example illustrates the inv~ntion with heavy-wei~ht, nonapertured, jet-tracked nonwoven fabrics of hydraulically entangled ~taple fibe~s of poly(~-phenylene terephthalamide). The ~abrics have outstanding tensile characteristics.
Two batts of poly(~-phenylene terephthalamide) staple fibers were prepared. Each bat~ consisted of three layers of webs that were ~ormed on a Rando-webber air laydown machine from 3/4 inch 11.9 cm~ longand 1.5 denier [1.~ dtex] T-29 Revlar~ aramid fibers.
The fibers were commercially available from E. I. Du Pont de Nemours ~nd Compan~. Batt l-a weighed 14.7 oz/yd2 [498 g/m2] a~d Batt l-b weighed 16.4 oz/yd2 [556 g/m2].
Each batt was then placed on Screen C and forwarded at a speed o~ 10 yards per minute [9.14 meters/min~ under rows o~ c~lumnar j~ts o~ wat~r ~upplied for orifice ~ets C. ~upply pressure to ~uccessive rows o~ jets, was 500 psi [3450 kPa~ to the ~ir~t row of je~s ollowed by 3,300 psi [22,740 kPa] to each of ~he next ~hree row~ o~ jets. The same &equence of jet treat-ments was then given through the oppositP surace ~f the bakt.
¦ Table I lists the total energy-impact , .5 product (ExI~ and the ~tal energy expended in the ¦ hydraulic jet treatment along wi$~ prope~ties of the resultant nonapertured ~abric. The average ~ the MD
and XD strip tensile strength of the fabrics are ! plotted in the Figure and show the extra~rdinarily hi~her strip tensile strength.of these fabric3j,0f, the invention, as compared to the ~ighest stri~ tensile strenyth exhibit d by same w~ight of prior art fabrics.
~he fabrics of this example have ~trip tensile ~trengths that are about 7.7 to 9O2 times those of the prior art fabrics of comparable weight.

. _ . . . .. . .

TABLE I
Fabrics o Exam ~e 1 ~att l-a Batt l-b Unit weight oz/yd~ 14.7 16.4 [~m/m 1 [498] 1556]
Energy-Impact Product Hp-hr lbf~lbm 0.l23 O.ll9 [106 JN/k~] . ~3-231 12.. 8~]
Energy Hp-hr/lbm 0. 76 0 . 68 [106 J/kg] 14.4~] 14.0l]
Grab Strength MD, lb/in 334 357 [N~cm] [5B4] 16241 XD, lb/in 492 500 ~N/~m] 186l] 1875J
Strlp Tensile Strength*
~D, Note l 13.0 11.5 ENote 2] [0.673 [0.59]
XD, N~te l 13.8 ll.6 Note 21 10-711 [0.60]
Alternat~ Exten5ion ~ycles ~lO~ >~00 Jet Track~
2S per inch 20 20 ~per cm~ [7~87~ ~7.873 _~
I *Foo~note~: l. Strip tensile ~trengths are in ¦ (lb~in)~oz/yd~)

2. Bracketted values of strip tensile ~trengths ~re i~ lN/cm)/[g/~2~.
E~AMPLE 2 This example *urther illu~trateg the invention with heavy-weight~ nonapertured, j8t-tracked nonwoven ~abrics Df hydraulically entangled staple fibers o~ poly(m-phenylene isophthalamide).

~ 1 ~

3~
~ 11 ~
Two batts o~ Nomex~ ar.~mid staple fibers were prepared by an air-laydown process of th~ type describ~d in Zafiroglu, U.S. Patent 3,797,074. Th2 Nomex~ fibers were availahle commercially from E. I. du Pont de Nemours and Company and are made ~rom poly(m-phenylene isophtl~al2mide) polymer. Batt 2-a consisted essentially of a ~7/33 blend of 1.5 inch 3.8 cm~ long and 1/4 inch ~0.64 ~m] long staple fibers o~ 2 denier [2.2 d~ex~. Ba~t 2-b consis~ed - 10 essentially of 1 inch [2.5 cm] long fibers of 2 denier 12.2 dtex~. Batts 2a and 2b were treatcd with column~r hydraulic jets to form fabrics respectively weighing 7,0 and 8.6 oz/yd2 [237 and 292 g/m J. Table II sum~arizes the sequence of jet treatments. The first five rows of j~t~
impact one face of the batt; the other rows, the other face.
TABLE II
_ Batt 2-~ Batt 2-~
Orifice S~rt , Pressure ~rifioe ~uppor~ ~ressure SetScreen psi IkPa] SetScreen ~si [kPa]
20 C C 500 [3450] B C 700 14820]
D ~ 400 ~27~0] ~ C 700 [4820]
C C ~00 ~5519~ A A S00 [3450]
C 2000 [137aO] ' `~ A `' ' 500 ~3450]
C C 2000 [137B03 i A 2000 [13780]
25 D A 800 [5510] C D S00 ~41303 C A 1600 [110293 C D 1100 [7580]
C ' ~ 2000 [13780] ' 'C D 'l2000 Ll3780]
C A 2000 ~137803 C D 2000 113780]
D A 2900 [13780~ `
The t.otal ExI pr~duct and energy expended in the treatment o~ Batts ~-a and 2~b are summariz d in TablP III along with the characteristics of the resultant ~abrics~ Th~ average strip tPnsile ætrength of the batts is plotted in ~he Figure and again shows the ~trength 35 advantage of the ~abri~s o~ thi~ example over similar prior art fabxic:s of . he ~ame weight.

TABL
Fab_ ics O~ Example 2 Batt 2-a Batt 2-b Unit weight 7.~ 8.~
oz/yd~ [237J ~292J
lg~m23 Energy-Impact Product Hp-hr lbf/lbm 0.05~ 0-039 [106 JN/kg3 11.37] 11~03]
Energy ~p-hr/lbm 0.65 0.46 1lO~ J/kgJ [3.84~ [2.71]
Grab Strength MD, lb/in 118 119 lN/cm] 1207i [20RJ
XD, lb/in 116 106 [N~cm~ [203] ~186]
Strip Tensile ~trength*
~D, Note 1 B.6 5.7 ~Note 2~ [0.44J [0.29] `
X~, Note 1 7O0 5.3 lNote 2] ~0 36 ] [
Alternate Extension Cycles >11~ 51 Jet traclcs per i nch 20 10 per c:m] [ 7 9 ]

*Footnote~: 1. Strip tensile ~trengths are in ~lb/in)/
(oz/y~23 2. Bracketted values of ~trip tensile 30strengths are in lN/cm) / (g/m2) ~2~

EXAMPLE 3 , . .
This example illustrates the productlon of~abrics of the inventi~n from p~ly(ethylene terephthalate) staple fibers o~ 1.35 denier [1.5 dtex]
and 3~4 inch [1.9 cm] leng~h. The fabrics exhibit excellent ten~ile characteristics and resista~ce t~
disentanglement. The four fabrics were prepared as described in the following paragraphs.
Batt 3-a was prepared on Rando-webb~r equipment and then treated ~quentially by hydraulic jets ~rom orifice set C while being forwarded at 10 yards/min [9.14 m/min] on screen ~upport C. The batt was treated by sev~n rows of jets. The first four rows of jets treated one side ~ the batt and the remaining three rows the other side o the batt. The jet ~upply pressure was 200 psi ~1380 kPa] ~or the first row of jets and 800 psi [19290 kPa3 for the remaining rows ~f jet~O ~
Batt 3-~ was formed ~y means of an air-laydown apparatus of the type di~closed in Z~flroglu, .S. Patent 3,797,074 and then, while being forwarded at 10 yards/min l9.14 m/min] t was treated sequentially by seven rows of jets. ThP first four rows treat one side of the batt; the last three rows ~rea~ ~he other side. While under the first row of 3ets, the bat~ is on ~upport creen C; on screen A while under the next three rows; and on ~creen B while .under the last three rows. The fir~t row of jets was ~upplied through orifice ~et ~ at a pressure of 1000 psi ~6890J kPa.
The next three rows were supplied through orifice sets D respec ively at pressures of 500, 1500 and ~000 psi [3450, 10340 and 13780 kPa]. The inal three rows were supplied through orifice sets D respectively at pressures of 500, 1500 and 2000 psi [3450, 10340 and 13780 kPa].

~ 1~;3f~3~;~

Batts 3-c and 3-d were formed on a similar air laydown apparatus as use~ for Batt 3-b, but one that gave more MD direction stxength t~ the batt.
Batts 3-c and 3-d were subjected ~o rows ~f hydraulic jets while being ~orwarded at 13.6 yards~min [12.4 m/minJ. For Batt 3-c, one face o the ba~t was subjected in sequence to one row of j~ts supplied through orifice set E at 1590 psi [10340 kPa~ while on screen support C, and then while on screen 6upport B, to one row 9f jet~ supplied through orifice set C at 500 psi [3450 kPa] and 4 rows of jets ~upplied through orifice set D at 2000 psi ~13780 k~a~ Then, the other face of the batt was ~ubjected while on creen suppor~ o the sam~ sequence of rows of jet~ as the first face except that the very first row of ~et~ was omitted.
This treatment was repeated ~or Batt 3~d, except that the first row of jets was replaced by two rows of jets (which treated only the irst ~ace of the batt), the first being ~upplied at 1300 p~i tB960 kPa) through orifice ~et B and the ~econd, through orifice E at S00 psi [345~ kPa].
: The total ExI product and the energy expended in forming the our batts into ~abrics of the invention and the characteristics of the resultant fabrics are summarized in Tabl~ IV. The average 6trip tensile strengths, which are plotted in th~ Figure, clearly show the advantage of hese heavy-weigh~ fa~rics of ~he I invention over the comparable heavy-weight nonwoven ! fabrics of the prior art.

~L~3'~L~3~i~`3 T~BLE IV
Fal~ri~ Example 3 Batt 3-a 3-b 3-c 3-~
Unit Weight oz/yd2 21.3 ll.O 7.8 8.~
[gm/m J 1722] ~373] 1264] {278]
ExI product Hp-hr lf~/lbm 0.056 0.0124 0.0354 0.0337 ~106 JN/kg~ 11.47] [0.33~ ~0.93] 10.89J
Energy hp-hr/lbm 0.41 0.29 0.71 0.71 1lO6 J/~g~ Z2.4~] 1l.7l~ [4.19~ [4.19 Grab Strength MD, lb/in 357 231 156 l67 ~N/cm~ [625] [404J [273] [292]
XD, lb/in 324 l89 93 95 lN/cm~ [567] 13311 [l63] [166]
Strip Tensile*
MD 3.3 8.9 ll.6 9.5 2~ [0.43] [0.46] [0.60~ [0,~9]
XD 7.7 7.4 ~.6 400 [0.3~] 10.38] [0.24]. ~0.21]
Cycles~* >lOO ~lOG 1~2 55 3et Tracks per inch 20 20 20 lO
rper Gm~ [7.9] t7.91 [7.93 13.~]

* See Table l footnotes for units of strip tensile strength.
! ~* Alternate extension cycles 3~ EX~MPLE 4 In this example ~taple ~ibers of polyethylene texephthalate of different d~nier~ and of di~f~rent lengths are blended together to form bat~s which are then treated with columnar streams of water to ~ 35 obtain ~tr~ng, nona~ertuxed, heavy-weight nonwoven 16 ~
fa~rics of the present invention.
Three hatts of blended polyester fibers were prepared by the same air-laydown pxocess as used in Example 2. Two o~ the batts labelled 4-a and ~-b were made with a 50/50 blend of l l/4~inch [3.~ cm]
long,6-denier 16.7-dtex] fibers with l~4-i~ch [0.64-cm] long,l.35-denier [~.5-dtex] fibers. ~he third batt, 4-c, contained a 67/33 blend respectively of these fibers. These batts were forwarded at lO
yards/min [9.14 m/min] through columnar water jets, supplied through ori~ice sets D while ~uppor$ed in sequence on S~reens C, A and Bo While on Screens C and A the jets entered through one ~urface of the batt, ~nd while on Screen B, the je~s entered through the opposite surface. The se~uence of jet ~upply pressure was as given in Table V. The total ExI pr~duct and the energy expended in treati~g the three batts are listed in Table VI along with the characteEistic6 of ~he resultant ~abrics. ~he average trip ~ensile ~trength of he fabrics ar~ plotted in the Figure.
The data clearly æhow the advantage in tensile strength o these ~abrics of the invention over similar prior art fabric~ ~ the ~ame weight.
!

rL23~ L3 - 17 ~
~ABLE V
~ b ~at~ 4-c S~reen Pr~ssure Screen Pressure ~ psi IkPa] ~ si lkPa]
20~ 11380] C 200 11380]
A 500 ~3450J A 500 [3450]
1800 112400] ~ 1500 [10340]
A 2000 ~13780] A 1800 [1~400]
B 500 ~3450~ A 2000 [1378Q]
B 1800 [12400] A 2000 ~13780 B 2000 ~13789J B 500 [3450]
~ 1500 ~lg3~0]
B 1800 [12400]
R 2000 ~13780]
~ ~ 1137~0]

. . .

.1, T LE V
Fabrics o Exam~le 4 Batt 4a 4b 4c Unit Weight oz/yd 9~1 703 8.g [g/m2~ ~308~ 12473 1302 ExI Product Hp-hr lbf/lbm 0.018 0~022 0.033 ~0 JN/kg] ~0.47~ 10.58] 10.87 Energy Hp-hr~lbm 0.39 0.49 0.73 1lO6 J/kg] 12.303 ~2.89~ 14.3l]
Grab Strength MD, lb/in 213 l90 221 ~N/cm] [373] 1333] ~387 XD, lb~in 195 159 l84 [N/cm] ~34l~ 1278] 1322]
Strip Tensile*
MD 10.8 11.2 9.9 10.56~ [0.58] [0.5l~
XD B.7 9.7 8.4 10.~5J [o.~01 10-~3]
Cycles** ~0 5l 52 J~ ~ra~s per inch ~0 40 40 ~per cm] 1lS.7~ 115.7] ~15.7]

. __ * See T~ble I footnot2 for unit~ of strip t~nsile strength.
** Alternate extensi~n cycles ~3~r3~

X~MPI,E 5 This example illustrates the production of a nonwoven fabric of the invention ~rom a 50/~0 blend of l.5_inch 13.8-cm] long, l5-denier ~l6.7-dtexJ with l/4-inch [0.63-cm] long, 1.8-den 12-d~ex] s~aple fibers of 66 nylon. The fiber blend was ~ormed into a bat~
with an air laydown apparatus ~f the type disclosed in Zafiroglu, U.S. Patent 3,797,074. The batt was then ~orwarded at 8.0 yards/min 17.3 m~ters/min]
through rows of hydraulic jets, while ~upp~rted on screens~ The sequence Df treatments wa~ as follows:
Orifice ~upport Pressure Set Screen psi [kPa]
C C 500 ~3450]
~ B 500 134503 D B lS00 [10340 D E 500 [3450~
D E l500 [10340]
~0 ~ ~ 2000 ~13780]
While he batt was on screen~ C and B, the ~ets impinged on one ~ur~ace of the batt and ~hen while ~he bat~ was on screen E, he jets impinged on ~h~ o~her ~urface of I the batt. As a result of ~he treatment a strony, di~entangl~ment resistant, heavy weight, nonapertured nonwoven fabric was formed whose characteris~ics are , summarized in ~able VII. As ~how~ by the plot of average ~trip t2n5ile versus unit weight the fabric i6 ~ar ~uperior in tensile strength to prior art.
!

.

- ~o -TABLE VIX
Fabrics of Exam~l~ 5 Unit Weight oz~yd~ 13 [g/m 3 [441 Energy-Impact Product Hp hr lb~/lbm 0.023 [106 JN~kg] [0.60]
Energy Hp-hr/lbm 0.34 [106 J~kg~ 12.01]
Grab Strength MD, lb/in 240 [~/cm] [420]
XD, lb/in 202 [N~cm] 1354]
Strip ~ensile Strength*
MD, Note 1 8.3 lN~t~ 2] l~ 43]
XD, Note 1 5.7 [Note 21 10-29]
~lternate Extension Cycles 98 Jet Tracks per inch 20 lper ~m] ~7.9]

Footnotes: 1~ Strip tensile str~ngths are in ~lb/in~/(oz~yd ~
2~ Bracketted values o~ strip tensile s~rengths are i~ ~N/cm)~g~m2)

Claims (2)

WHAT IS CLAIMED IS:

1. An improved process for preparing heavy-weight, nonapertured, nonwoven fabric by treating batts of staple fibers of synthetic organic polymer with rows of fine columnar streams of water while the batts are supported on a foraminous screen and are moving perpendicular to the rows of streams, the improvement comprising for stronger fabrics, preparing the fabric from batts having a unit weight of 200 to 850 g/m2 and consisting essentially of staple fibers having a length in the range of 0.6 to 5 cm and a decitex in the range of 1 to 18, the batts being treated immediately after preliminary consolidation and wetting by a row of streams which forces portions of staple fibers from one surface of the batt through the thickness of the batt to the opposite surface of the batt, said row of streams being spaced at a frequency in the range of 3 to 10 per centimeter and being supplied from orifices having diameters in the range of 0.13 to 0.22 mm.

2. A process of Claim 1 wherein the unit weight is in the range of 240 to 510 g/m2, the fiber length being in the range of 1.3 to 3.8 cm, the fiber decitex being in the range of 1.4 to 2.5 dtex, the orifice frequency being in the range of 3 to 6 per cm, the streams being supplied at a pressure in the range of 6890 to 22740 kPa.