GB2236771A - Stitch-stabilized non woven fabric - Google Patents

Abstract

A stitchbonded nonwoven fabric which comprises a fibrous layer is reinforced in a first direction with bulkable thread and in a second direction with substantially inextensible thread, the reinforcing directions being at an angle of at least 50 degrees with each other, exhibits superior strength, resistance to splitting and repeated washability. The bulkable thread may be spandex wrapped with inelastic thread, or textured polyester nylon or polypropylene. The inextensible thread may be the bulkable thread and be inextensible during the stitching. It may be laid as wefts before stitching or the two threads stitched together. The bulkable thread may be deformed out of the plane of the fabric by chemical action, moisture or 50 to 200 degrees C, heat to contract the fabric. <IMAGE>

Description

TITLE Stitch-Stabilized Nonwoven Fabric BACKURQUND QF-TUE 1NYZNT1QX Yield

of-the Invention This invention relates to a stitchbonded nonwoven fabric and a process for producing It by multi-needle stitching a nonwoven fibrous layer with two thread systems. More particularly. the invention concerns such a fabric and process for making It wherein one of the thread systems is a bulkable throadl the other is a substantially inextensible thread, and the threads is are arranged In repeating patterns to form a drapable, durable, soft nonwoven fabric that Is strong In both the longitudinal and transverse directions.

Peogription ot the Cgiar-art Nonwoven fabrics have long been used in a variety of applications. Unbonded (i.e., not bonded) nonwoven fabrics most often have been used In applications that require little strength and durability.

Such unbonded fabrics generally lacX surface stability and often come apart when washed or laundered. To strengthen such fabrics, support layers often have been combined with the unbonded fabric. Strength has also been Improved by bonding the fabric with a resin binder or binder fibers incorporated in the fabric. in addition to strengthening the fabric. bonding improves fabric stability and durability. However. bonding also makes the fabric stiff and boardy. Multi-needle stitching (i.e.# atitchbonding) of unbonded nonwoven fabrics has also been used to inrease fabric strength mainly in the direction of the stitching.

SS-2625A 09/07/90 11:09 E.I. DLPONT 003 2 Use of bonded and unbonded. bulked nonwoven fabrics In disposable swim wear. towels, wash cloths, training pants for Infants. baby wipe, scouring, padat mattressest cushion, sleeping bags and the like ham been disclosed, for example. by Wideman, United States Patent 4,606,964. Norman. United States Patent 4.657f802i column 1, line 301 through Column 4. line-32. discloses a large nu mbe r of elastic nonwoven web& for use as diaper components. filters. bandages, wearing apparel. and the like. Neither patent mentions stitchbonded fabrics.

Multi-needle stitching machines.. such as 11Arachnell. I'Llbast, or "Mali" machines (including Malimo.

Malipol and Maliwatt machines) have been used to Insert is stitches Into a wide variety of fibrous substrates. Such machines and some of the fabrics produced therewith are disclosed by X. W. Bablo, "New Pabrics Without weaving", Papers of the Alaerican Association of Textile Technology.

Inc.# pages 51-54 (November, 1965). other disclosures of the use of such machines appear for example. in Ploch et al, United States Patent 3,769,815, Hughes, United States Patent 3#649j428 and Product Licensing Index. Research Dinclosuref 0Stitchbonded products of continuous filament nonwoven websO, page 30 (June, 1968). Warsop. United Ztates Patent 4,306,429, discloses a novel stitchbonded fleece made with incompletely threaded front and back bars of a nulti-needle stitching machine. Hughase United States Patents 3,329.552 and 3.649.428, disclose other stitchbonded fabrics made with two thread systems.

Howeveri none of these disclosures concern stitching of a nonwoven fibrous layer with bulkable thread.

Multi-needle stitching of nonwoven fibrous layers with elastic thread (a type of bulkable thread) on one-bar stitchbonding machines Is discloved by Zatiroglu# United States Patent 4,773f238p to raae dust cloths.

Although each of the aforementioned nonwoven fabrics have been used with some successt their utility 2 3 could be significantly enhanced by improvements In their combinatlx>n of strength. softness, washability and durability properties. An object of this invention Is to provide such an Improvement.

StftY PE THE =VENTION The present invention provides a stitchbonded nonwoven fabric made with two thread systems. The fabric comprises a nonwoven fibrous layer that is reinforced in a first direction with a bulkable thread which forras &paced-apart rows of stitches In the fibrous layer and is reinforced with substantially Inextensible thread in a second direction which Is at an angle of greater than 50 degrees with the first direction. In one e"odiment of the invention, the bulkable and the substantially Inextensible threads are each multi-needle stitched through the nonwoven fibrous layer. In other embodiments. reinforcement in the second direction in provided by inlay stitches or by multiple, spaced apart.

parallel threads laid on the surface of the nonwoven fibrous layer and fastened thereto by the stitching of the first thread system. Ueudlly? the weight of the threads amounts to no more than 20% of the total weight of the nonwoven febrict but for economy, often 2 to 10%t and sometimes as little as 3 to 5%. Suitable bulkablO thread includes textured thread of polyester, nylon, polypropylene, or the like, and composite thread such as clastomeric yarn (a.g.0 spandex) In an extended state wrapped with inelastic nylon or polyester. Usually, the stitchbonded nonwoven fabric has a unit weight in the range of 10 to 300 grams per square metert preferably 20 to 200 g/m2. The row spacing usually Is in the range of 2 to 10 rows per centiracter. preferably 3 to 6 per em.

The stitch spacing usually is in the range of 2 to 15 stitches/on. preferably 4 to 12 per em.

bulking of the bulkable threads (a) increases entanglement of the threads with the fibrous layer and 3 09/07/90 11:10 E.I. DUPONT 005 4 enhances fabric stability and durability. and (b) Causes gathering of the fabric. which results In a mortar hand, improved drape# and decreased stiffness.

The present invention also provides a process for making the above-described atitchbonded nonwoven fabric. In accordance with the process, a fibrous layer, weighing In the range of 15 to 150 grant per square meter. is fed to a multi-needle stitching machine equipped with a two-thread system. The first thread system Is a bulkable thread which is stitched into the fibrous layer In parallel rows of stitches at a spacing in the range of 2 to 8 rows per centimeter and with the stitches within each row having a spacing In the range of is 1 to 7 stitches per centineteri preferably 2 to 5 per c=.

The bulkable thread is stitched under sufficient tension so thati it the bulkable thread Is a textured yarn, the textured yarn is essentially straight and. it the bulkable thread Is wrapped elastomeric yarn. the wrapping thread Is essentially straight. The bulkable yarn reinforces the fabric in a first direction. The second thread system Is a substantially inextensible thread that is incorporated to provide reinforcement In a second direction which forms an angle of greater then 50 degrees with the first reinforcing direction. The inextensible thread can be incorporated by stitching within the same ranges of the row spacing and stitch spacing as in the first thread system. In other e diments ot the process. the Inextensible thread, rather than being stitched Into the fibrous layer. Is incorporated as inlay stitches. or Is laid onto the fibrous layer in multiple, spaced apart. parallel rows and then fastened to the layer by the bulkable thread stitching. In each e diment of the process, the stitching thread Is under sufficient tension to maintain. after stitching# its original length. After the stitching operationt tension on the stitching threads is released threads. the 4 v r_. 1. WtUN 1 W0b OW/ v( =Fti bUlkable threads are bulked and the area of the fabric is thereby reduced by 5 to 80%.

DRIEF DESCRICTION Of THE DRAWINGS The Invention will be readily understood by reference to the drawings In which:

Pigure 1 is a diagra=atic representation of a fabric of the inventiod made by multi-needle stitching into a nonwoven fibrous layer (not shown) chain stitches of bulkable threads 10 and 1-0.3-4 NtrICOV Stitches Of substanti ally Inextensible threads 20; Pigure 2 Is similar diagrammatic representation of a fabric of the Invention In which chain stitches of bulkable threads 10 Were multi-needle is stitched into a nonwoven fibrous layer (not shown) over an array of parallel, substantially inextensible threads that wore laid onto the fibrous layer; and rigure 3 is a diagram that shows the angles formed by a typical Intersection of the reinforcing directions of the two thread systems (i.e.f the intersection of the thread portions that are located between successive courses of stitches placed in the fibrous layer).

DETAILED DESCRIPTION OE CREFERRSQ RMBOMMENTS

The invention will now be described In detail with regard to a preferred stitchbonded fabric of the invention. The fabric Is made from a fibrous layer and two thread systems, one thread system being of bulkable thread which provides reinforcement In a first direction.

and the second thread system being of substantially inextensible thread which provides reinforcement in a second direction that Is at an angle of at least 50 degrees with the first reinforcement direction.

Various starting fibrous layers are suitable for use in the present Invention. such as batts of carded fibers. air-laid fiber batts. wood-pulp papers. lightly bonded and unbonded nonwoven sheets. and the like. The E.I. DUPONT 007 6 torn OfiberO, an applied to the fibrous layer, means staple fibers of textile denier, pulps, fibrids and the like. The fibers can be natural tIbers or of synthetic organic polymer. The fibrous layer batts or sheets usually are supplied In wound-up rolls. If heavier fabrics are desired, two or more batts or sheets can be positioned upon each other to torn the fibrous layer tor subsequent stitching. However, a single batt or sheet Is preferred for easier processing and lower cost.

As used herein, the term 11bulkable thread" refers to a thread or yarn which Is "bulked" by being deformed out-of plane. The deformation is Induced by releasing tension from the thread or by exposing the is thread to chemical action. moisture and/or heat at a temperature of about 30 to 2000C.

The term Ogathered" Is used herein to describe the surface of the stitchbonded nonwoven fabric of the invention and to Indicate that the final tabric'area in no more then 95% of area of the fibrous layer from which it was made. (that Is, the area before the fibrous layer was multi-needle stitched and/br bulked).

in accordance with the process of the present Invention, the stitching operation is performed with a conventional multi-needle stitching (11stitchbonding11) machine, equipped to handle two yarn systems. Malimo or Liba stitching machines are particularly useful.

Substantially any strong bulkable thread is suitable as the stitching in the first direction. The bulkable thread provides a force that causes the fibrous layer to contract or gather when the thread is subjected to a bulking treatnent (.g., exposure to moisture, steant heat, or chemicals).

A particularly preferred bulkable thread Is formed from spandex clastomeric yarn of high elongation and retractive power which has been wrapped with an inelastico substantially inextensible yarn. Such threads 6 09/07/90 11:12- E.I. DUPONT 008 7 are available commercially. The bulkable thread is stitched into the shoot under substantial tension so that the substantially inextensible wrapping yarn is straight and so that the bulkable thread will retract during the bulking stop to as little as 2o percent of Its original length after bulking.

Any substantially Inextensible thread can be used for stitching In the second direction. Inextensible threada of nylon or polyethylene terephthalate are preferred. The substantially Inextensible thread adds strength to the fabric In a direction that Is at an angle of at least 50 degrees to the reinforcing direction of the bulkable thread stitching. The substantially is inextensible thread is substantially Inextensible while being stitched and its length is not be substantially increased after stitching. However. the substantially inextensible thread can be a bulkable thread which Is substantially inextensible during the stitching but then retracts and becomes shorter and and as a result Is extensible after bulking. A preferred bulkable thread used in the capacity of a substantially Inextensible thread is the aforementioned elastomeric yarn wrapped with inextensible yarn and stitched under tension as sufficient to straighten the wrapping yarn.

Usually the threads supplied by the two thread systems amount to no more then 20k ot the weight of the stitchbonded fabric. For economy however, the weight of stitching thread often.amounta to only 2 to 10k of the total fabric weight and sometimes an little as 3 to 54.

In a preferred embodiment of the Inventiont the first system of bulkable thread forms rows of chain stitches In and along the length of the fibrous layer.

In another embodiment the bulkable thread forms a series of interlocked loops on one surface of the fibrous layer and a parallel series of zigzag tricot stitches on the other surface. Such rows of stitches are typical or 7 09/07/90 11:12 E.I. DLPONT 009 a those made by a "Mall'$ or an "Aretchnoll or C@Ltba" multi-needle stitching hine. With regard to area contraction or gathering caused by retraction Qt the bulkable stitching. chain stitches cause almost all gathering to be In the longitudinal direction of the stitched layer and tricot stitches cause gathering across the width as well an along the length of the fabric.

In accordance with the Invention, the second thread system provides multi-needle stitching and reinforcement in the second direction with substantially inextensible thread, The thread forms chain stitches, tricot atitchosi Inlay stitches or any other commonly used stitching, with the proviso that the angle between is reinforcing directions of the bulkable and Inextenalble threads Is at an angle of at least so degrees. In an alternative embodiment. multiple, spaced apart. parallel substantially Inextensible threads are arrayed on a surface of the fibrous layer and stitched to the layer by the bulkable thread system.

In the manufacture of nonwoven fibrous layers used as starting materials for the stitchbonded fabrics of the Inventionj more strength Is usually developed in the longitudinal (machine or 11MD11) direction then in the transverse (cross-machine or IIXDII) direction. For the stitchbonded fabrics of the present Invention, It is advantageous to arrange the bulkable threads in the stronget or longitudinal direction and the substantially inextensible threads in the weaker or transverse direction. Reference herein to a first direction generally means the longitudinal direction (11MD11) and reference to a second direction generally means the transverse direction# although such is not required.

The rows ot stitches generally have a spacing In the range of 1 to 7 stitches per cm, preferably 2 to 5.

Chain stitching with bulkable thread Is preferred in the first direction thread and OtricotH stitching with 8 A - J.-) jjur-ul-41 W110 9 substantially Inextensible thread Is preferred in the second direction.

With reference to the drawings attached hereto, note that Figure 1 represents a stitchbonded fabric of the Invention In which bulkable thread 10 is in the form of chain stitching in the strong direction of the starting nonwoven fibrous layer and inextensible thread is in the form of 1-0#3-4 13-across tricot" stitching In the week direction of the nonwoven fibrous layer. The angle between the reinforcing directions of the two thread systems is greater than 50 degrees. (The method of determining the angle Is given hereinafter with regard to Figure 3,) For the fabric rep[resented in Figure 1, the is angle would be at least 72 degrees, If the stitch Spacing and needle spacing were equal Pigure 2 represents a stitchbonded fabric of the invention In which bulkable thread 10 forms chain stitches in the strong (OMDII) direction of the nonwoven fibrous layer# Inextensible thread 20 in arrayed on the.

surface of the fibrous layer parallel to the weak direction of the fibrous layer with the chain stitching of bulkable thread 10 fastening the array to the layer.

The angle between the reinforcing directions of the two -thread systems is 90 degrees.

Usually, the inextensible threads are stitched, laid in or arrayed in the transverse (i.e., the usually weaker) direction of the fibrous nonwoven layer. In come instances howevert for example. When the fibrous layer Is formed by crosslapping, the transverse direction may be the strong direction of the fabric. under such circumstances, it Is often preferable to use the bulkable thread In the transverse direction to apply tricot or other patterned stitches.

Pabric characteristics and properties are measured by the following procedures.

Unit weight of the starting fibrous layer and of 9 09/07/90 11:14 E.I. DUPONT 011 the final stitchbonded fabric are measured in accordance with ASTH D 3776-79. The weight of thread per unit area of fabric is determined by removing and weighing the thread from a given area of fabric.

Fabric weight is determined by weighing a known area of sheet which was cut while It was flattened between plates.

Percent area gather of a fabric is determined measuring Its dry area, before (Ai) and after (A.) the fabric has been wetted thoroughly with water. Drying Is performed at 250OF for 10 minutes. The wetting and drying treatment causes the fabric to gather. Percent area gather, G, In then calculated by the formula is %G m 100 (AI - Ag)/A1.

Washability is determined by exposing a fabric aample to repeated washing and drying cycles In a home laundry automatic washer and tuable dryer and when applicable, recording the total nu mbe r of cycles until failure (I.., until the samples show tears, holes, or other signs of disintegration, or more than Sk weight loss). The washing and drying Is conducted In accordance with AATCC Test Method 135-1978 for washing and t umb le drying# "AATWO Is the American Association of Textile Chemists and Colorists.

Grab strengths are measured at 700P and 65t relative hunidity using an Instron tensile testing machine. Grab strength Is determined In general accordance with ASTN Method D-1117-800 on a 4-1nch (10.2 em) wide by 6-inch (15.2 c=) long sample. A gauge length of 3 inches (7,6 ca). clamps having I-Inch (2.5 em) wide jaws. and an elongation rate of 12 Inches (30.5 em) per minute are used. The grab strength is reported In pounds force. For each reported monsurementi ton determinationa wore made in the machine direction (NO) of the fabric and ton ware mnde In the transverse direction (TD) (i.e.# perpendicular to the MD). The average of the 05/07/90 11.14 E.I. DUPONT 012 it MD and the TD measurements are reported separately. Grab strengtho wore measured for wet (i.e., after being thoroughly oocked in water) and dry samples (a as madef (b) after one washing and (c) after five washings. The washing and drying were conducted In the same equipment as was used for the washability test.

The "hand oplit" test in a subjective evaluation of the handling strength of a fabric. The fabric to be tested is pressed on a smootht flat surface with two thumbs touching and the thumbs are repeatedly drawn apart in an attempt to cause the fabric to split It the fabric splits without stitching thread breakage, the fabric fails the test. If the fabric cannot be split without breaking the stitching thread# the fabric passes the test.

The angle at which the direction spaced apart rows of stitches formed by the first thread system intersect& the second direction of the spaced apart rows formed by the second thread system. can be determined by plane geometry from the stitch diagrams of the two thread system. The angles can also be determined by simple geometry by examining the straight line segments of the threads between courses with the fabric held in an.extended (but not deformed) condition. The direction of Z!r the spaced apart rowsis the direction that the straight line portions of the threads travel In proceeding between successive courses. In warp knitting, these straight line segments are often referred to as the "floats" of the stitches. To illustrate the determination, Figrure 3 -30 shows an intersection between vertical floats 10 of chain stitches falling along the longitudinal exIs (ND) of a fabric of the Invention and floats 20 of the second thread system of that fabric. The float and reinforcing directions coincide with each other. The angles formed JS between the two directions of floats are "all and 0b11 and the angle that the floats make with the transverse 0 1 09/07/90 11:15 E. 1. DUPa4T 013 12 direction (TD) la RC01. The present invention requires that the angle between between the directions the two thread systems be greater then 50 degrees, Thus, the angle nall and Ob" each must be greater than 500. AG shown in this illustrationt the angles are calculated in degrees by the relationships:

a m 90 - 0 b m go + c c m tan"l (L/ns) wherein L is the spacing between successive courses of stitches (or the reciprocal of the nu mbe r of stitches per unit length in the fabric direction inserted by the is machine), Is the spacing between rows of stitches Is (equal to the needle spacing# or reciprocal of the gage of the multi-needle stitching machine), and n is the number of needle spaces traversed by the second thread system In proceeding between successive courses.

RY-AMPTIT's The following examples illustrate the preparation of multi-needle stitched nonwoven fabrics In accordance with the Invention and compare then to similar multi-needle stitched nonwoven fabrics which are outside the invention. In the Examples, samples of the invention are designated with Arabic numerals; comparison samples have an upper case letter in their designations.

Several types of fibrous starting layers are used to prepare the fabrics described in each example.

The fibrous layers range from the weakest and least durable wood-pulp paper of Example 1 which falls apart when socked In water, to the fairly strong and durable.

but not washable and launderable. point-bonded web of a blend of staple ribers of Example 5. Further specific details of the fibrous layers are given in each example.

12 13 in the examplest all the stitched samples and comparisons. bulkable threads were multi-needle stitched with a stitch frequency of 11,5 stitches per inch (4.5 per cm) in the first or longitudinal direction (also called Hmachine direction" or I'MW'). in samples and comparisons that wore also stitched in a second direction, substantially inextensible throads and a Otgagell of 14 stitches per Inch (5.5 per centimeter) were employed. The bulkable threads were stitched In a chain stitch and the substantially Inextensible threads were "laid-in" stitches or Otricot" stitches with floats traversing one or two or four needle spaces. In the surmary tables of the exalopiest the following is designations were used to identity the particular thread systems and stitch patterns.

Thread system&.

1..0. An inextensible, 40-den (44-dtex), 34-filament flat nylon thread.

V-1. A bulkable, 40-den (44-dtex), 13 filament, textured nylon knitting yarn.

V-2. A bulkable, 20-den (22-dtex) spandex filament wrapped with 40-den (44-dtex) nylon.

1-1. Sane as V-1, but In extended and substantially inextensible state when stitched.

1-2. Same a$ V-2. but in extended and-substantially inextensible state when stitched.

Stitch patterns:

P. Pillar stitch (or chain stitch) T-1. Closed Tricot or 1 and 1 lept 1-Ofl-2 T-2. Closed 2 and 1 lept I-0j2-3 T-3. Closed 4 and 1 lapf I-0f4-5 L-1. 001-morosell Inlay (0-0,2-2) L-2. 02-acromell Inlay (0-0j3-3) L-3. 114-acroseth Inlay (O-OtS-5) Por each examplei a summary table identifies for each sample of the invention and each comparison sample 13 14 and reports stitching threads and stitch patterns that ware used to construct the sample and the percent area gather and minimum angle (a or b of rig, 3, haver 19 smaller) between the reinforcing directiona. Each table also reports the measured wet and dry grab strength. hand splittablityi and washability of each sample.

EXAMPLE 11

In this example. two nonwoven fabrics of the invention are made from a fibrous layer or pure pine wood paper pulp containing no binder resins and nominally weighing 1.2 oz/yd2 (407 g/m2). The samples of the invention (1-1 and 1-2) are stitchbonded with a two thread system, one of which supplies bulkable thread.

is The stitchbonded samples are compared to the fibrous layer without stitching (A-1) and with stitchbonding that In outside the invention (A-2. A-3). This example demonstrates the extraordinary strength that is added to ordinary paper (that usually falls apart when simply immersed in water) after it has been stitchbonded In accordance with the Invention. Samples 1-1 and 1-2 of the invention ore highly suited for use as wet or dry wipe-cloths Table 1 below summarizes the preparation of the samples and their resultant proportion.

A-1 through A-3 are comparison samples which lock adequate stitching to stabilize the fabric in accordance with the Invention. The 1-across tricot stitching in made with an angle of 39o between the threads of the two directions (ices. angle alpha between the longitudinal direction of the row of chain stitches with their vertical floats and the float of the tricot atitcheop as Illustrated In Figure 1). The 2-across stitching Is made with an angle of 590 and the 4-across.

with an angle of 730. Results of the testing are reported in Table 1.

14 lot%/ 10 110 10 C. 1. Vur-UP4 1 Table 1 - Exampl" Sample Fabric Weight.

oz/yd2 1.39 1,73 2.12 2.06 2.04 9/M2 47.1 58.6 719 69,8 69,2 First Thread System None Y-11 V-1 Y-1 Y-2 Pattern P P P P Second Thread System None None 1-0 1-0 1-2 Pattern L-2 T-3 Minimum Angle, degrees 39 59 73 Grab Strength, as made Dry MD# lb force 13.3 5510 23.7 25,3 25.4 Newtons 59 245 105 113 113 Dry TD, lb force $.S 245 1906 28.8 29,4 Newtons 38 11 87 128 131 Wet NDf lb force 0.5 37.4 16.4 1902 23,6 Newtonts 2.2 16.6 77 85 105 Wet TD# 1b force 0 0 15.8 28.2 29.2 Newtons 0 0 70 125 130 Hand Split Test Wet PAIL PAIL PAIL PASS PASS Dry PAIL FAIL PAIL PASS PASS The superior strength exhibited by the samples stitchbonded according to the invention versus the comparison samples, Is evident from the reported grab strengths and hand-splittability results. The comparison samples tailed the splittability test; both fabrics of the invention passed. All Samples failed the washability test. The short# loose fibers of the unbonded fibrous starting layer are believed to be the source of the failures. lloweverf samples 1-1 and 1-2 of the Invention still made very good reusable dry or wet wipes.

EXAMPLE 2,

This example Illustrates preparation of nonwoven fabric by multi-needle stitching a fibrous starting layer is 05/07/90 11:17 E. I. DUKkAT 017 16 In the form of a reinforced paper ot 1.2 oz/yd2 (40.7 91M2) made from a mixture of 75 weight 4 paper pulp and 25% 1.35-don (1.5-dtex). 0.5-Inch (1.27-cm) long fibera of polythylene torephthelate. The construction and measured properties of the samples are summarized in Table 2 halow. In contrast to the strength and washability of the samples of the Invention 2-1. 2-2 and 2-3f all comparison samples failed to survive more than five washing cycles test and all tailed the hand splittability test. Not. c that comparison sample B-1 had no stitchbonding threads and B-2 and B-3 each had only one yArn system.

EXANCLE 3.

is This example describes preparation of two stitchbonded samples of the Invention (3-1 and 3-2) from a fibrous layer which Is a 1.9 oz/yd2 (64.4 g/n2), spunlacod. two-layer reinforced paper. one layer being of pine wood paper pulp and amounting to 60 % of the composite weight and the other layer being of 1.35-den (1.5-dtex)i 7/8-inch (2.2-cm) long fibers of polyethylene terephthalate and amounting to 40% of the composite weight. Pour comparison samples were also made with the can fibrous layer: C-1 having no atitchbonding; C-2 and C-3 each having but one stitchbonding thread system# and C-4 having two thread systems# one bulkable and one inextensible. a minimum angle between the reinforcing directions of only 39 degrees (versus at least 50 degrees according to the invention). Table3 summarizes the sample constructions and shows how very well the fabrics of the Invention withstand repeated wash cycles, - more than 75 washes for ample& of the Invention versus fewer than 2 for comparison samples.

09/07/90 1,1:17 E.I. DUPONT 019 17 T&h11k 2 - ZR&MJR10 2 Sample Fabric Weight.

OZ/ d2 1.23 1,65 2.0 2.1 2.1 2,1 g/0 41.7 55.9 67.8 71.2 71.2 71.2 First Thread none Y-1 none Y-1 Y-1 V-1 Pattern p "M p p p Second Thread none none 1-1 1 to 1-0 1-2 Pattern T-1 T-2 L-3 T3 Kinimura angle 59 73 73 % Area Gather SD 9 11 13 17 65 Grab Strengths As Iftade Dry MD, lbs 6.3 23.2 25.1 30.6 25.1 25.1 Newtons 28 103 112 136 112 112 Dry TD, lb 5.4 1.6 3.2 20.4 j3.8 24.0 is N 24 7 14 91 150 107 Wet MDt lb 3.3 18.1 22.1 29.t 24.4 21.8 N is 81 98 131 109 97 Wet TD, lb 3.2 1.1 2.6 20.8 28.6 325 N 14 5 12 93 127 127 After 1 wash Dry MDt lb 500 18,3 23,5 35.7 22.3 24.3 N 22 81 105 159 99 109 Dry TDi 1b 3.2 205 11.1 35.8 29.8 43.5 N 14 11 49 159 133 194 Wet MDj, lb 3.5 16.6 19.9 35.8 20.4 20.2 N 16 74 89 159 91 90 Wet TDO lb 2.4 14 4.4 26.9 28.5 32.5 N 11 6 20 120 127 145 After 5 washes Dry MDt lL FW M 23.0 37.8 18.1 23.2 N M rw 102 168 81 103 Dry TDt lb rw FW 5.8 36,2 39.3 39.8 H M FW 26 161 175 177 Wet MDi lb FW rw 16.6 37.4 15.0 24.1 N M M 74 166 67 107 Wet Tbf lb 1M FW 76 28.3 22.6 37.3 N rw rw 34 126 101 166 Hand Split Tent Wet pail Fall Fail Pass Pang Page Dry Fail pail Fail Pass pass pang Number of Washes until failure 1 1-2 5 55 75+ 75+ No:tos; SD - Sample deteriorated in water.

M - Failed wash test.

17 09/07/90 11: 1E3 E. I. DUPONT 019 18 Table 3 -Example Sample 9=2 9=1 C=4 2_=1 I=Z Fabric Weight.

oz/d2 1.9 2,2 2.3 2.6 2.4 2.4 9/M 64 76 78 88 81 81 First Thread none Y-1 none Y-1 Y-1 Y-2 Pattorn -W p p p p Second Thread non none 1-0 1-0 1-2 Pattrn T-1 L.l T-2 T-3 Minimum angle M- 39 59 73 Area Gather -- 20 17 12 19 69 Grab Strengths As made Dry MD, lbs 37.2 39.9 39.4 70.5 43,0 34.9 Newtons 166 177 175 314 191 155 Dry TD# lb 20.1 7.3 10.2 8.4 41.0 39.0 is W 89 32 45 37 182 174 wet MDt 1b 32.1 32.7 32o3 75.9 34.8 30.0 H 143 146 144 338 155 134 Wet TDt lb 16.2 6.5 9.8 11.3 33.0 33.8 m 72 29 44 so 147 150 After 1 wash Dry Mbf lb rw rW 33.2 rW 35.6 38.2 N FW M 148 rw 158 176 Dry TD, lb rw FW 6.5 rW 41.7 33.5 X M rW 29 rW 186 149 Wet MD, lb PW FW 22,7 rw 32.3 4594 N M rW 101 M 144 202 Wet TDt lb ?W FW 5.4 FW 34.9 28.1 N M 7W 24 FW 155 125 After 5 washes Dry HDO lb M rw M M 37.6 43,1 N FW M PW M 167 192 Dry TDi lb rW FW rw FW 41.0 33.9 W FW M M M 182 151 Wet MDt lb M rw rW M 28.9 583 N rW M rw FW 129 259 Wet TDO lb rw rw rw M 35.7 281 H rw rw rw M 159 125 Hand Split Test Wet Fall Fail Fail Pass Pass Pass Dry Pall Fell rail Pass Page Pass Number of Waohes until failure 0 0 2 1 75+ 75+ Not not measured or Inapplicable. See Table 2 for other notes.

18 C5/07/50 11: id L. 1. ULCUN 1 Wde 19 in this example two stitchbonded samples of the invention (4-1 and 4-2) are prepared with two yarn systems and a 1.2-oz/yd2 (40.7-g/m2) lightly spunlaced web of 7/8-inch (2.2-cm) long, 1.35-den (1.5-dtex)fibers of polye4%-.hylene terephthalate. Three comparison samples are also prepared with the sane til?rous layer: D-1 which has no stitching; samples D-2 which Is stitched with only one yarn system; and D-3 which Is stitched with two thread systems that do not provide the minimum angle betwebn between the reinforcing directions of the stitching. Table 4, below, which summarizes the sample constructions and measured characteristics, again is demonstrates the advantages in strength and repeated washability of the stitchbonded fabrics of the invention over comparison samples.

UMLR A This example illustrates the advantages of the invention with stitchbonded fibrous layer which Is point-bonded carded web. The web is formed from a blend of 75 weight percent of 1.5-Inch (3.8-cm) long, 1.5-den (1#7-dtex) acrylic fibers and 25 % of 3-inch (7.6-cm) long. 3-den (3.3-dtex) polyester fibers of lower melting -temperature than the acrylic fibers. The web was point bonded at 100 pal (689 kPa) and 1600C with a regular pattern of 625 points per In2 (96.9/CM2), each point having a diameter of 0.020 Inch (0.05 mm). Two such samples of the Invention, 5-1 and 5-2, are compared with three comparison samples. The comparisons are: E-1, the point"bonded web without stitching; and E-2 and E-3, which are each stitched with only one thread system.

Table 5. below, surmarizes the construction and properties of the samples and again shows the clear advantages in strength, resistance to splitting and repeated washability of the fabrics of the Invention over the comparison samples.

19 09/07/90 11:19 E.I. DUPONT 021 Table 4 Exaln121 a 4 Sample Fabric Weight.

OZ/ C12 1.16 1.43 1.64 1.57 5.3 19/M 393 48.5 55.6 53,2 51.9 First Thread none Y-1 Y-1 Y-1 V-2 Pattern p p p p Second Thread none none 1-0 1-0 1-2 Pattern T-1 t-2 T-3 minimum angle -- 39 59 73 % Area Gather -- 14 21 22 72 Grab Strengths As made Dry NDO lbs 24,6 29.5 25.3 28.4 64.8 Newtons 109 131 113 126 288 Dry TDt lb 1193 4.0 12,9 1492 22.4 is N so 18 57 63 100 Wet MDt lb 18.6 29.6 29.3 23.3 56.8 X 83 132 130 104 253 Wet TDO Ib 10.5 6.9 11.6 14.4 226 N 47 31 52 64 101 After 1 wash Dry MD, lb 205 22.9 rw 18.4 64.5 N 91 102 M 82 287 Dry TDt lb 1018 94 M 12.6 38.2 N 48 42 rW 56 170 Wet NDO lb 18.6 21.7 M 18.0 61.9 N 83 97 FW 80 275 Wet TD, lb 9.3 8.5 rw 12.0 33.5 X 41 38 M 53 144 After 5 washes Dry MDf lb 18.2 M M 19.3 68.3 N $l M M 86 304 Dry TDi lb 1100 M M 15.3 38.0 N 49 FW rW 68 169 Wet MDt lb 19.5 M M 19.9 62.0 N B 7 M 89 276 Wet TDt lb 9.2 M 13.8 33.5 N 41 FW rw 61 149 Hand Split Test wet Full Pail Pail Pass Pass Dry rail rail Pall Pass Pass Page Number of Washes until failure 5 2 2 75+ 75+ NOtRE: SaMe as in Thble 3.

1. VUrUN 1 U 21 Table 5 - Example s Sample Fabric Weight.

OZ/ d2 2.1 2.4 2.5 2.7 2.6 g/M 714,2 81.4 84.8 91.5 88.1 Pirst Thread none Y-1 none Y-1 Y-2 Pattern p- -- p p Second Thread none none 1-0 1-0 1-2 Pattern T-1 L-3 T-J Minimum angle -- -- 73 73 4 Area Gather 14 10 l$ 64 Grab strengths As made Dry MD, Ibs 13.6 20.0 10.0 34.0 36.6 Newtons 61 89 89 151 163 Dry TD, ib 1.0 9.5 6.6 30,8 25.7 is N 4.5 42 29 137 114 Wet MD, lb 12.8 19.1 15.1 29.1 32.8 N 57 85 67 1.37 114 Wet TDf lb 1.3 8.5 5.5 27.6 17.9 N 5.9 38 24 123 146 After 1 wash Dry 14D, lb M FW 15.4 33.4 43.2 N M FW 69 149 192 Dry TDt lb rw M 9.1 35,7 37.3 N rW rW 40 159 166 Wet VID f lb rw FW 14,7 26,3 45.1 N rw FW 65 117 203.

Wet TDi lb FW FW 9,2 30.6 35.4 N rW 41 136 158 After 5 washes Dry MD? lb rW FW M 33,0 45,2 N M FW M 147 201 Dry TDi lb rw rW rw 37.0 37.1 N rw M M 165 165 Wet MDt lb rw M M 31.3 43.1 N FW FW 139 192 Wet TDt lb FW FW 26.3 38.2 N M 117 170 Hand 5Plit Test Wet fail fail fail pass pass Dry fail tall fail pass pass Number of Washes until failure 0 0 2 60 75+ Natax: Same as in Table 3.

21 p

Claims (14)

1. I# A stitchbonded nonwoven fabric made with two thread systems. the first thread system being a bulkable thread and the second thread system being a substantially Inextensible thread. the fabric comprising a nonwoven fibrous layer that is reinforced in a first direction with the bulkable thread which forms spaced-apart rows of stitches in the fibrous layer and Is reinforced with the substantially Inextensible thread in a second direction which Is at an angle of at least 50 degrees with the first direction.
2. 2. A stitchbonded nonwoven fabric in accordance with claim 1 wherein the bulkable and the substantially is inextensible threads are each multi-needle stitched through the nonwoven fibrous layer.
3. 3. A stitchbonded nonwoven fabric in accordance with claim 1 wherein the reinforcement in the second direction is provided by Inlay stitches.
4. 4 A stitchbonded nonwoven fabric in accordance with claim 1 wherein the reinforcement In the second direction is provided by multiple. spaced apart parallel threads laid on the surface of the nonwoven fibrous layer and fastened thereto by the stitching or the first thread system.
5. 5. A stitchbonded nonwoven fabric in accordance with claim 1. 20 3 or 4, wherein the weight of the threads amounts to no more than 20% of the total weight of the nonwoven fabric.
6. 6, A stitchbonded nonwoven fabric in accordance with claim 5 wherein weight of the threads amounts to 2 to 10% of the total weight of the nonwoven fabric.
7. 7. A atitchb-oziel nonwoven fabric in accordance c with any one of claims/ wherein the bulkable thread Is a textured thread of polyester. nylon or polypropylene.
8. 8. A stitchbonded nonwoven fabric In accordance 1 to 6 with any one of claims /wherein the bulkable thread is an olastomeric yarn In an extended state wrapped with an Inelactic yarn.

   9. A stitchbonded nonwoven fabric In accordance with claim a wherein the alastomeric yarn Is spandax and the inelastic yarn In nylon or polyester.

   10. A stitchbonded nonwoven fabric in accordance 1 to 9 with any one of claims /wherein the bulkable thread and the substantially Inextensible thread are the same.

   11. A process tor making a stitchbonded nonwoven fabric of claim 1, comprising feeding a fibrous layer.

   weighing in the range of 15 to 150 grams per square meter, to a multi-needle stitching machine equipped with a two-thread system, the first thread system being a bulka ble thread which is stitched Into the fibrous layer-in parallel rows of stitches at a spacing in the range of 2 to 8 rows per centimeter and with the stitches within each row at a spacing in the range of 1 to 7 stitches per centimeter.

   the bulkable thread being stitched under sufficient tension to maintain the thread straight during stitching and the bulkable yarn reinforcing the fabric in a first direction, and the second thread system being a substantially inextensible thread which Is incorporated in the fabric and reinforces the fabric in a second direction that forms an angle of at least 50 degrees with the first reinforcing direction.

   12. A process In accordance with claim 11 wherein the inextensible thread is incorporated by stitching at the row spacings; and stitch spacings in the same ranges as In the first thread system.

   13. A process in accordance with claim 11 wherein the Inextensible thread Is Incorporated as inlay stitches.

   23 24 14. a process In accordance with claira 13 wherein the bulkable yarn forms rows of chain stitches and the inlay atitches are 0-0,5-5 stitches.

   15. A process in accordance with claim 11 wherein the Inextensible thread in laid onto the fibrous layer In multiple, spaced apart. parallel rows and then fastened to the layer by the bulkable thread stitching.

   16. A process in accordance with claim 11 wherein the tension on the stitched threads is released and the bulkable threads are bulked to cause gathering of the fabric.

   17. A process in accordance with claim 17 wherein the area of the fabric Is reduced by 5 to 80%.

   is 18. A process in accordance with claim 11 substantially as hereinbefore described with reference to the accompanying Drawings or in any one of the aforegoing Examples.

   19. A stitchbonded nonwoven fabric in accordance with claim 1 substantially as hereinbefore described with reference to the accompanying Drawings or in any one of the aforegoing Examples.

   1 r, 24 Amendments to the claims have been filed as follows 1. A stitchbonded nonwoven fabric made with two thread systems, the first thread system being a bulkable thread and the second thread system being a substantially inextensible thread, the fabric comprising a nonwoven fibrous layer that is reinforced in a first direction with the bulkable thread which forms spaced-apart rows of stitches in the fibrous layer and is reinforced in a second direction with the substantially inextensible thread which forms spaced-apart rows of stitches in the fibrous layer, the second direction being at an angle of at least 50 degrees with the f irst direction.

   2. A stitchbonded nonwoven f abric in accordance with claim 1 wherein the reinforcement in the second direction is provided by inlay stitches.

   3. A stitchbonded nonwoven f abric in accordance with claim 1 wherein the weight of the threads amounts to no more than 20% of the total weight of the nonwoven fabric.

   4. A stitchbonded nonwoven f abric in accordance with claim 3 wherein weight of the threads amounts to 2 to 10% of the total weight of the nonwoven fabric.

   5. A stitchbonded nonwoven fabric in accordance with any one of claims 1, 2, 3 or. 4 wherein the bulkable thread is a textured thread of polyester, nylon or polypropylene.

   6. A stitchbonded nonwoven fabric in accordance with any one of claims 1, 2, 3 or 4 wherein the bulkable thread is an elastomeric yarn in an extended state wrapped with an inelastic yarn.

   7. A stitchbonded nonwoven fabric in accordance with claim 6 wherein the elastomeric yarn is spandex and the inelastic yarn is nylon or polyester.

   2G 8. A stitchbonded nonwoven fabric in accordance with any one of claims 1, 2, 3 or 4 wherein the bulkable thread and the substantially inextensible thread are the same..
9. 9. A process for making a stitchbonded nonwoven fabric of claim 1, comprising feeding a fibrous layer, weighing in the range of 15 to 150 grams per square meter, to a multineedle stitching machine equipped with a two-thread system.

   the first thread system being a bulkable thread which 10 is stitched into the fibrous layer in parallel rows of stitches at a spacing in the range of 2 to 8 rows per centimeter and with the stitches within each row at a spacing in the range of 1 to 7 stitches per centimeter, the bulkable thread being stitched under sufficient 15 tension to maintain the thread straight during stitching and the bulkable yarn reinforcing the fabric in a first direction, and the second thread system being a substantially inextensible thread which is stitched into the fibrous layer in parallel rows of stitches at a spacing in the range of 2 to 8 rows per centimeter and with the stitches within each row at a spacing in the range of 1 to 7 stitches per centimeter, the substantially inextensible yarn reinforcing the fabric in a second direction that forms an angle of at least 50 degrees with the first reinforcing direction.
10. 10. A process in accordance with claim 9 wherein the inextensible thread is incorporated as inlay stitches.
11. 11. A process in accordance with claim 10 wherein the bulkable yarn forms rows of chain stitches and the inlay stitches are 0-0, 5-5 stitches.
12. 12. A process in accordance with claim 9 wherein the tension on the stitched threads is released and the bulkable threads are bulked to cause gathering of the fabric and reduction of the fabric area by 5 to 80%.
13. 13. A process in accordance with claim 9 substantially as hereinbefore described with reference to the accompanying Drawings or in any one of the aforegoing Examples.
14. 14. A stitchbonded nonwoven fabric in accordance with claim 1 substantially as hereinbefore described with reference to the accompanying Drawings or in any one of the aforegoing Examples.

    r, Publ shed 1991 at The Patent Office, State House. 66171 High Holborn. London WC1 R 47P. Further copies may be obtained from 1 1 Sales Branch. Unit 6, Nine Mile Point Cwmfelinfach. Cross Keys. Nrt NPI 7HZ. Printed by Multiplex techniques lid. St Mary Cray. Kent.