MXPA00006103A - Nonwoven webs having improved softness and barrier properties - Google Patents

Abstract

A nonwoven material including at least a meltblown web is stretched by about 1-35%in at least one direction using a short-distance drawing process, to provide a fabric having improved softness and liquid barrier compared to otherwise similar fabrics prepared using longer drawing distances. The drawing process may include one or multiple stages. When multiple stages are employed, the fabric has adequate liquid barrier at a lower basis weight.

Description

NON-WOVEN FABRICS THAT HAVE SOFTNESS AND IMPROVED BARRIER PROPERTIES Field of the Invention This invention is directed to non-woven fabrics having an improved smoothness and penetration barrier. The invention is also directed to a method for preparing non-woven fabrics.

Background of the Invention Soft non-woven fabrics of entangled fibers or filaments are known, for example, from U.S. Patent 4,443,513, issued to Meitner et al. Soft non-woven fabrics, and the laminates thereof are useful in applications where the softness and volume are desired attributes including cleansers, garments, surgical covers diapers and the like. Non-woven fabrics can be melt blown thermoplastic fiber fabrics as described in United States of America No. 4,307,143 issued Meitner. These meltblown fabrics can be produced by melt blown polypropylene or other thermoplastic through a die having a row of openings striking heated air at the die outlet to pull the filaments, forming microfibers which are then cooled and collected on a wire in motion. The non-woven fabric may also be a laminate including a meltblown sheet, for example a laminate including thermoplastic fabrics bonded with a blown fabric with melting therebetween. Laminates of spunbonded / meltblown / spunbonded fabrics are described in U.S. Patent No. 4,041,20 issued to Broc et al. Weaves bonded with purely spun, for example not laminated to a co-melt blown fabric, are also known in the art.

U.S. Pat. No. 4,443,513 discloses that the softness, volume, and fall of non-woven fabrics can be improved through the proper selection of filament bonding patterns in a non-woven fabric, and / or by a controlled stretch of the tissues. The controlled stretching takes place under an ambient or cold temperature. Stretching is limited to the elongation required to break the fabric. The thermoplastic n-elastic fabrics described can be stretched about 1.2-1.4 times their original length.

Even though fabrics bonded with yarn promote strength, meltblown fabrics are known to provide a barrier to liquid penetration, including liquids under pressure. Therefore, meltblown fabrics, or laminates of fabrics bonded with spinning and meltblowing, are generally employed in applications requiring both softness and liquid barrier. There is always a need or desire for fabrics that have an improved liquid barrier, particularly in medical applications involving surgical hospital suits and the like.

Definitions The phrase "non-woven fabric" means a fabric having a structure of individual fibers or threads, which are interleaved in a repetitive manner, but not in an identifiable manner. Non-woven fabrics have been formed, in the past, through a variety of processes such as, for example, meltblowing processes, spinning processes and carded and bonded weaving processes.

The "autogenous bond" means the joint provided by the fusion and / or self-adhesion of the fibers and / or filaments without an applied adhesive or externating bonding agent. The autogenous bond can be provided by contact between the fibers and / or filaments while at least a part of the fibers and / or filaments are semi-melted or sticky. The autogenous bond can also be provided by mixing an adhesive resin with the thermoplastic polymers used to form the fibers and / or filaments. The fibers and / or filaments formed from such a mixture can be adapted to self-join with or without the application of pressure and / or heat. The solvents can also be used to cause the fusion of the fibers and filaments which remain after the solvent is removed.

"Fusible blown fibers" means fiber formed by extruding a thermoplastic material melted through a plurality of usually circular and fine matrix capillary vessels such as melted threads or filaments into a gas stream (eg, air) at high speed. , which attenuate the filaments of the melted thermoplastic material to reduce its diameter, possibly a microfiber diameter. Then, the co-melt blown fibers are carried by the high velocity gas stream and deposited on a collecting surface to form a melt blown fiber fabric and randomly disbursed. The process is discussed, for example, in the patent of the United States of America No. 3,849,241 granted to Butin, whose description is incorporated herein by reference.

"Yarn-bonded fibers" refer to small diameter fibers, which are formed by extruding a melted thermoplastic material or filaments from a plurality of usually circular and thin capillaries of a spinning organ with the diameter of the extruded filaments being then rapidly reduced such as, for example, by the eductive pulling or other well-known spinning mechanisms. The production of non-woven fabrics bonded with yarn is illustrated in the patents such as, for example, in United States of America Patent No. 3,802,817 issued to Matsuki et al. And in United States of America Patent No. 5,382,400 granted to Pike and others The descriptions of these patents are incorporated herein by reference.

The term "polymer" generally includes, but is not limited to homopolymers, copolymers, such as, for example, alternating block, graft, random copolymers, terpolymers, mixtures, and modifications thereof. In addition, unless specifically limited in another way, the term "polymer" will include all possible geometric configurations of the material. These configurations include but are not limited to isotactic, syndiotactic and random symmetry.

"Bicomponent fibers" refers to fibers which have been formed from at least two polymer extruded from separate extruders but spun together to form a fiber. The polymers are arranged in different zones placed essentially constant across the cross section of the bicomponent fibers and extend continuously along the length of the bicomponent fibers. The configuration of such bicomponent fibers may be, for example, a sheath / core arrangement where one polymer is surrounded by another or may be a side-by-side arrangement or an arrangement of "islands in the sea". The bicomponent fibers are taught in U.S. Patent No. 5,108,820 issued to Kaneko et al., In U.S. Patent No. 5,336,552 issued to Strack et al. And in European Patent No. 0586924. the fibers of two components, the polymers can be present in proportions of 75/25, 50/50, 2/75 or any other desired proportions.

The "biconstituent fibers" refers to fibers which have been formed from at least two extruded polymer from the same extruder as a mixture. The term "mixture is defined below." The biconstituent fibers do not have the various polymer components arranged in different zones placed relatively constant across the cross-sectional area of the fiber and the various polymers are usually not continuous throughout. The entire length of the fiber, instead of this, usually forms fibrils which begin and end at random.The biconstituent fibers are sometimes referred to as multi-constituent fibers Fibers of this general type are discussed in, for example, the United States of America No. 5,108.82, issued to Gessner, The bicomponent and biconstituent fibers are also discussed in the textbook "Polymer and Compound Mixture" by John A. Manson and Leslie H. Sperling copyright 1976 by the Plenum Press, a division of Plenum Publishing Corporation, New York, New York, IBSN 0 306-30831-2, pages 273 to 277.

The "mixture" means a combination of two or more polymers while the term "" alloy "means a subclass of mixtures wherein the components are immiscible but have been compatibilized. The "miscibility" and l "immiscibility" are defined as mixtures having negative and positive values, respectively for the free energy d mixed. In addition, "compatibilization" is defined as the process of modifying the interfacial properties of an immiscible polymer mixture in order to make an alloy.

"Microfibers" mean fibers of small diameter having an average diameter no greater than about 100 microns, for example, having an average diameter of about 0.5 microns to about 50 microns, or more particularly, an average diameter of about from microwaves to around 40 micras.

The "nonwoven fabric binding pattern" is a bonding pattern between filaments in the non-woven fabric which is imparted during the manufacture of the non-woven fabric.

The "interfiber union" means the union produced by the entanglement between the individual fibers to form a coherent tissue structure without the use of a thermal bond. This entanglement of fibers is inherent in meltblowing processes but can be generated or augmented by process such as, for example, hydraulic entanglement or needle piercing. Alternatively and / or additionally, you can use a binding agent to increase the desired bond and to maintain the structural coherence of the fibrous tissue. For example, the powder binding agents and the chemical solvent bonding can be used.

"Liquid pressure resistance" (also known as the "hydro head") refers to the ability of a composition or a film made therefrom to withstand the application of a liquid charge without dripping. The resistance to the liquid pressure of a film depends on the thickness of the film, the composition of the film material, how the film is made and processed, the surrounding ambient, and the test method. Methods for testing resistance to liquid pressure of a film or material include, without limitation, the hydrostatic pressure test described in method 5514 of standard Federal test methods No. 191A, which is equivalent to the method of AATCC test 127-89 and test method INDA 80.4-92.

The phrase "consisting essentially of" does not exclude the presence of additional materials which do not significantly affect the desired characteristics of a given composition or product. The example materials of this class will include, without limitation, the pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, particles and aggregate materials to improve the processing of the composition.

Synthesis of the Invention The present invention relates to a woven fabric having an excellent softness and an improved liquid barrier (hydro head resistance), and laminates including nonwoven fabric. The invention also includes a process for making the nonwoven fabric.

The non-woven fabric of the invention includes meltblown fabric. The non-woven fabric may be a single-layer nonwoven fabric (meltblown), or it may be laminated from a meltblown fabric to one or more additional woven fabrics. The additional non-woven fabrics can be further meltblown fabrics, spunbonded non-woven fabrics, bonded and bonded fabrics, or any woven fabrics that can be advantageously used in combination with the melt blown fabric. The melted blown fabric, with or without other non-woven fabric can also be combined with a plastic film, foam rubber or other entity.

The non-woven fabric is heated and stretched between two or more pairs of pull rollers. It has been found that the pulling rollers can be configured so that the stretching causes the non-woven fabric to have improved hydro head resistance as well as improved softness Specifically, the pulling distance (for example the distance over which the non-woven fabric is pulled between the two adjacent walls of the pull rollers is maintained at less than about 35 inches by a single phase pulling process including only two pairs of the adjacent pull rollers while the heated non-woven fabric is stretched for about 1% to about 35% of its initial length, ideally, the pulling distance is maintained at less than 10 inches while the non-woven fabric is heated it stretches by about 1% about 35% of the initial length.

In another embodiment, the non-woven fabric is pulled in multiple phases using three or more pairs of pull rollers When multiple phases are employed, the total pulling distance (for example, the sum of the distance between the adjacent pairs of the pulling rollers) is maintained to less than about 35 inches while the non-woven fabric stretches around 1% to around 35% of its original length. A main advantage of using a multiple phasing process (as opposed to a single phase pull) is that the product has a lower basis weight after pulling, allowing a comparable product to be obtained having a larger area with an adequate liquid barrier and softness.

Other advantages of short distance pulling, either single-phase or multi-phase are reduced shrinkage of non-woven fabrics during stretching, increased cup crush resistance, and increased tensile strength.

The foregoing and other features and advantages of the invention will become apparent from the following detailed description of currently preferred embodiments, read in conjunction with the accompanying examples and drawings. The detailed description, the examples and the drawings are intended to be illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and the equivalents thereof.

Brief Description of the Drawings Figure 1 illustrates an apparatus which can be operated as a single phase or multiple phase pulling unit which is useful for preparing a nonwoven fabric according to the invention.

Figure 2 shows the softness of cup crushing for non-woven samples prepared using the single-phase and multi-phase jalad.

Figure 3 shows the hydro head values of the non-woven samples prepared using a single-phase and multi-phase pull.

Figure 4 shows the basis weight for the non-woven samples prepared using the single-phase pull and the multi-phase pull.

Detailed Description of Current Preferred Incorporations Figure 1 illustrates an apparatus 100 which can be used for the single-phase or multi-phase stretching of a non-woven fabric. A nonwoven fabric 110 travels along a path indicated by arrow A around guide roll 112, guide roll 116, and through seal 119 between a first pair of pressure point rolls 11 and 120. Then, the fabric 110 passes through a joint 12 between a second pair of pressure point rollers 122 and 124 through a joint 127 between a third pair of rollers d pressure point 126 and 128, through a joint 131 between a fourth pair of pressure point rollers 130 and 132, through a joint 135 between a fifth pair of pressure point rollers 134 and 136, and around the guide roller 138.

The apparatus 100 is capable of several operation modes, and the following is merely illustrative of the practical additions. The various rollers may be made of a metal such as aluminum or steel, of hard rubber, or of several hard or slightly elastic materials Where two rolls (for example 122 and 124) are adjacent to form a pressure point, one of the rollers, (for example the large roller 122) can be made of metal, while the other roller (for example the small roller 124) can be a hard but slightly elastic material. This allows a light application of a small pressure in the pressure point seal 123 without causing undue deformation of the woven fabric n. The other pairs of pressure point rollers can be configured similarly. Also, the distance between the adjacent pressure point joints can be adjusted. For example, the distance between the pressure joints 119 and 12 can be adjusted by placing the pressure point rollers 122 and 124 closer to or further away from the rollers. d pressure point 118 and 120.

For a single phase pull, the fabric 110 can be preheated by heating the rollers 116 and 118. Alternatively, the fabric can be pulled without an added heat. For heated pulling, rolls 116 and 11 can be heated to a temperature that is above room temperature and below the temperature where the polymer in the fabric is softened and sticks to the rolls. For a polypropylene base fabric, roll temperatures of about 150 to about 250 ° F are preferred. The advantage of heating is that it allows a somewhat greater and / or faster stretch of the fabric if it causes breakage.

The second pair of pressure point rollers 12 and 124, and the third pair of pressure point rollers 126 and 128 can be used to effect single phase pulling of the 110 knit. For heated pulling, the larger rollers 122 126 they must be heated to the desired pulling temperature, for example about 150-225 ° F for the polypropylene fabric. The pulling was performed by simply turning the third pair of pressure point rollers 126 128 at a surface velocity higher than that of the second pair of pressure point rollers 122 and 124. For example, a 20% stretch can be achieved by making the fabric pass through the third pressure point joint 127 at a speed 20% faster than when it passes through the second pressure point joint 123. As explained above the pulling distance can varying by varying the displacement distance of the non-woven fabric 110 between the two pressure point joints 123 and 127.

The term "pulling distance" for a single phase pull refers to the distance by which the non-woven fabric travels between the two adjacent pairs of the pressure point rollers used for pulling, not including the distance over which The fabric is in direct contact with any roller. This is the distance over which the fabric can be pulled. The single phase pull can be effected between any two adjacent pressure point joints in the apparatus 100, by creating an increased tissue moving speed through the downstream pressure point joint compared to the gasket. upstream pressure For a single phase pull, the speeds of the pressure point rollers not used to effect the pull are adjusted so as not to affect the length of the fabric.

The multi-phase pull differs from the single phase pull in the sense that two pairs of the pressure point rollers, and more than two pressure point joints are used to effect pulling. For example, a pull of three phases of the fabric 110 can be effected using the second pair of pressure point rollers 122 and 124, the third pressure roller pair 126 and 128, the fourth pair of pressure points 130 132, and the fifth pair of pressure point rollers 134 and 136 To effect the three phase pulling, the pressure point rollers 126 and 128 rotate at a higher surface speed than the pressure point rollers 122 and 124. pressure point 130 and 132 turn at a surface velocity d greater than that of the pressure point rollers 12 and 128. The pressure point rollers 134 and 136 in turn rotate at a surface velocity faster than the surface velocity. pressure point roller 130 and 132.

The term "pulling distance" for a multiple phase d pull refers to the sum of distances over which the non-woven fabric is pulled in the various phases. For example, the fabric which is pulled over lengths of 6 inches in each of the three phases is exposed to a total pulling distance of 1 inch.

The present invention is a stretched non-woven fabric prepared using a total pulling distance of no more than about 35 inches, preferably less than about 25 inches, more preferably no more than about 10 inches, and more preferably no more. d about 6 inches. The non-woven fabric is stretched po about 1-35% of its initial length, preferably po around 3-20% of its initial length, more preferably by about 4-15% of its initial length. Stretching using the short distance pull makes the fabric have an improved softness while maintaining a superior hydro head strength and resistance, lower shrinkage and other desirable properties compared to a similar nonwoven fabric using a longer pulling distance .

The non-woven fabric should include a blown fabric with fusion. Meltblown fabrics in which the individual fibers are in close contact are useful and applications that require a hydro head and other barrier properties. The meltblown fabric is not limited to the basis weight. The base weight of the melt blown will generally be between about 0.1-3.5 ounces / square yard (osy) most commonly between about 0.3-2.0 ounce per square yard. Lower base melt blown fabrics are preferred because of their lower costs, they are generally more practical when the co-melt blowing fabric is part of a laminate.

The nonwoven fabric may include additional nonwoven layers. Examples of the additional nonwoven layers include spunbonded fabrics, short fib fabrics, carded and bonded fabrics, and the like. In a preferred embodiment, two fabrics bonded with outer yarn are combined with a blown fabric with internal fusion to create a combination of woven fabric joined with spinning / blowing co-melting / spun-bonding (SMS). Fabric laminates S have a wide variety of advantages, which are discussed in U.S. Patent No. 4,041,203 issued to Brock et al. The woven fabric can also be laminated to a polyolefin cloth or foam or other substrate.

The meltblown web, and other layers of non-woven fabrics, can be constructed of the same or different materials. A wide variety of thermoplastic materials are useful in the formation of nonwoven fabric layers including without limitation, polyethylene, polypropylene, polyamides polyesters, copolymers of primarily ethylene and C3-C12 alpha olefins (commonly known as linear low density polyethylene), copolymers of mainly propylene co-ethylene and / or C4-C12 alpha-olefins, and flexible polyolefins including the polypropylene-based polymers having both atactic and isotactic propylene groups in the main propylene chain. Other suitable polymers include, for example, polyurethanes, copolyether esters, block copolymers of polyether polyamide, ethylene vinyl acetate copolymers, polyacrylates, ethylene alkyl acrylates, polyisobutidene, and polybutadiene, copolymers of polybutideno-isoprene, block copolymers having the general formula ABA 'or A-such as copoly (styrene / ethylene-butylene), styrene-pol (ethylene-propylene) -styrene, styrene-poly (ethylene-butylene) styrene, polystyrene / poly (ethylene-butylene) polystyrene poly (styrene / ethylene-butylene / styrene) and the like. Constrained and / or metallocene-catalyzed polyolefins are also useful including those described in U.S. Patent Nos. 5,571,619 5,322,728; and 5,272,236, the descriptions of which are incorporated herein by reference.

Polymers made using metallocene and / or constricted geometry catalysts have a very narrow molecular weight range. The polydispersity numbers (Mw / Mn below 4 and even below 3 are possible for polymer produced from metallocene and / or constrained geometry.) These polymers also have a short chain branching distribution controlled in comparison to other polymers. It is also possible to use a metallocene catalyst system and / or constrained geometry to control the isotacticity of the polymer mu closely.

In a preferred embodiment, the non-woven fabric is stretched using a multi-phase process. It has been found that when the non-woven fabrics are stretched over a short total pulling distance as described herein, certain advantages of full pulling result in a series of small pulling steps. An advantage is that there is a lower weight basis product when the fabric is pulled using a series of smaller steps. This results in cost savings, due to less narrowing of the tissue to the lower base weight, and to a larger product area.

It is important that the same desirable properties of softness and liquid barrier can be achieved by using a lower starting weight material, when the nonwoven fabric is stretched using multiple phases. Preferably, the fabric is stretched in two or more phases. More preferably, the fabric is stretched in three or more phases.

The percentage of total stretch, and the total pulling distance, can be about the same if it matters whether the single phase or multiple phase pull is used. Therefore, the preferred ranges given above for e percent stretch and total pulling distance are applicable for single-phase and multi-phase processes. When a multi-phase process was employed, it is preferred, though not necessarily, that the phases were equal. For example, a total pulling distance of 7.5 inches can be achieved in three equal phases of 2.5 inches to achieve optimum improvement in physical properties.

Test Procedures The following test procedures were used in connection with the examples discussed below: Hydrostatic Head Test (Hydrohead) Hydrohead resistance was measured according to method 5514 of Standard Test Methods No. 191A, which is equivalent to AATCC which is Test Method 127-89 and Test Method INDA 80.4-92. These test methods are incorporated herein by reference.

Cup Crush Test (Softness) This test was used to determine the detectable softening of the non-woven material by using the pic charge and the energy units of the Sintech tension machine at a constant rate of extension (CRE). A constant rate extension machine is a test machine in which the rate of increase in specimen length is uniform over time. A sample of nonwoven material is formed inside a cup. One foot descends into the cup "crushing" "The sample, and the constant rate of extension, measures the peak load and the energy needed to crush the material. The results are a manifestation of the rigidity of the material. The more rigid the material is, the higher the peak load value.

To carry out the test, at least three random samples of the non-woven fabric were cut. Cad sample is 225 mm wide and 225 mm long. The constant rate extension machine is then prepared as follows Prepare the machine according to the manufacturer's instructions and use the conditions of the following steps of this section. 1. 1 Put the LOAD ADDRESS DOWN 1. 2 Put the EXTENSION ADDRESS DOWN. 1. 3 Set the MEASUREMENT LENGTH to 3.82 0.1 inches (97 ± 2.5 millimeters). This can be achieved by measuring the base plate to the top plan of the foot. 1. 4 Set the crosshead speed to 16.0 ± 0. inches / min (400 ± 10 mm). 1. 5 Set the voltage limit to return to 62.9%. 1. 6 Put the upper extension limit 2.6 inches (63 millimeters). 1.7 Set the energy to start reading 15 mm (0.61 inches). 1. 8 Set the energy to stop reading to 6 mm (2.46 inches). 15 2. Select and install a load cell that has the proper range for the material being tested.

Note 1: These placements can be installed manually on the Sintech equipment or the Sintech equipment is set up for test work using the DOS version. All placements can be installed using a computer disk which can be obtained from Roswell Te Standardization.

Note 2: In the placement instructions above (9.1.3 to 9.1.8) use italic numbers in bold to put the equipment.

The sample specimens are conditioned in a standard laboratory atmosphere of 23 ± 2 ° C and 50 ± 5% relative humidity. After the specimens are tested according to the following procedure: 1. Place the steel ring on the forming cylinder. 2. Center the specimen on the forming cylinder. 3. Slide the forming cup over the cylinder until the material is pinched between the cylinder and the steel ring. 4. Carefully lift the forming cup to verify that the specimen is pinched between the steel ring and the forming cylinder.

Note 3: If the specimen is not pinched by the ring and the cylinder all around, the specimen should be rejected . Place the forming cup on the upper part of the base plate.

Note 4: Make sure that the forming cup is firmly seated on the flange of the base plate. 6. Start the crosshead. 7. When the test has been completed, remove the specimen from the base plate. 8. For more specimens, repeat steps 1-7.

The peak load is then reported in grams per each specimen. The energy was reported in grams / mm for each specimen, and the results for the multiple specimens are averaged.

Base Weight The basis weight was determined by measuring the mass of the nonwoven sample and dividing by the area covered by the sample.

Examples The following examples were carried out with spunbonded / meltblown / spunbonded material manufactured by Kimberly-Clark Corporation. The co-meltblown / meltblown / spin-bonded material was a woven laminate bonded with polypropylene copolymer yarn (3% d ethylene), a melt blown fabric of polypropylene (including 10% polybutylene) and other woven fabric bonded with identical polypropylene copolymer yarn. The material co-spun / meltblown / spunbonded has an initial bas weight (before stretching of about 1.4-1.5 ounces per square yard). The material samples were stretched using either a single-phase or three-phase stretch, with an apparatus similar to that shown in FIG. 1 and described above. Pulling temperatures ranged from about 210-220 ° F. The spunbond / meltblown / spunbonded material has an initial width of about 20 inches, and was pulled using line speeds (unwound) d about 200 feet per minute.

Comparison of Pull Distance and Narrowing Percentage (Examples 1-3) Using a single-phase pull, the percentage of narrowing was measured for three samples stretched by 7% in longitudinal direction, using different pulling distances. The following results were achieved.

As shown above at a constant percent d linear stretch, the narrowing is improved (reduced) by a short pulling distance. The use of a 20-inch jalad distance showed a significantly improved narrowing compared to a pulling distance of 55 inches. The use of the 4-inch pull distance resulted in a significant additional improvement.

Comparison of Cup Crush (softness) and Pull Distance (Examples 4-6) Using a single phase pull, cup crush (smoothness) was measured for three samples stretched by 7%, using different pulling distances, the following results were achieved.

As shown above, the product's smoothness improved for the shorter pulling distance compared to the two long pulling distances.

Comparison of the Hydrohead (liquid barrier) with the Pull Distance and Pull Percentage (Examples 7-16) Using a single-phase pull, the samples were prepared at different pulling distances of different pull percentages, and tested for the hydro head.

Drawn as a matrix, the following relationship is shown between the pull distance, the percentage drawn and the hydro head.

As shown above, for each proportion of the stretch tested, the head strength was made higher as the pulling distance decreased. At a distance of distant pull, the stretch ratios below 7 and above 10% gave better headrests than the stretch rates of 7-10%.

Comparison of Base Weight Products with Pull Distance Pulling Percentage (Examples 17-27) Using a single-phase pull, the samples were prepared at different pulling distances and at different pull rates, and were tested for the basis weight of the product.

As shown above, the base weights decreased somewhat as the pull distance was lowered in each pull percentage. This is consistent with examples 1-3 which show that higher pulling distances cause greater constrictions, for example, a greater lateral contraction. Samples with superior constrictions will be expected to have higher base weights for a given percentage of pull.

However, it is surprising and unexpected that samples with the lowest base weights (occurring at the shortest pulling distances) also tend to have the highest hydroheat resistance as shown by examples 7-16 along with a softness slightly improved as shown by examples 4-6. Thus, for a particular stretch percentage, the use of shorter pulling distances gives superior non-woven fabric products having a superior liquid barrier and softness.

It is noted that many of the samples given above were tested for tensile strength. There was no noticeable change in the tensile strength of the product at different pulling distances.

Comparison of Single Phase and Three Phase Pulling (Examples 28-35) Samples were prepared using the single-phase and three-phase haul, at four different hauling percentages, and at a single pulling distance of six inches. For pulling multiple phases, the pulling distance of six inches was divided into three equal phases of two inches each. The following table summarizes the conditions used.

The samples were tested for softness, hydro head and base weight and the results were drawn. Figure 2 shows the percentage of pull against softness. At each pull level, the samples prepared using the three-phase pull had a slightly better smoothness, evidenced by lower cup crushing values than the samples prepared using the single-phase pull.

Figure 3 shows the hydro head against pull percentage. At pull rates that were shorter than 6% and 12%, samples prepared using the three-phase pull were somewhat lower but had adequate head strength values (better resistance to liquid pressure) than samples prepared using the pull of single phase. The trend was reversed to a pull of 19%.

Figure 4 shows the basis weight against the pulling percentage. At pull rates that were shorter than 6% and 12%, the samples were prepared using the three phase pull and having significantly lower base weights than the samples prepared using the single phase pull. This advantage disappeared to 19% of pulled.

In summary, at 6% and 12% pulling rates the multi-phase pulling produced highly improved products which exhibited a surprising combination of lower base weights and adequate hydro head resistance as well as improved softness compared to the products facts using the single phase pull.

Although the embodiments of the invention discussed herein are currently considered to be preferred, various modifications and improvements can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, all changes that fall within the range of equivalents are intended to be encompassed therein.

Claims (36)

R E I V I N D I C A C I O N S

1. A softened nonwoven material comprising a meltblown fabric, prepared by stretching a precursor nonwoven material in at least one direction for about 1-35% of its original length using a pulling distance of no more than about 35 inches, the softened nonwoven material has a higher head strength than that of an otherwise similar nonwoven material prepared using a pulling distance of at least about 55 inches.

2. The softened nonwoven material as claimed in clause 1, characterized in that the pulling is achieved in a single phase.

3. The softened nonwoven material as claimed in clause 1, characterized in that the pulling is achieved in two or more phases.

4. The softened nonwoven material as claimed in clause 1, characterized in that pulling is achieved in three or more phases.

5. The softened nonwoven material as claimed in clause 1, characterized in that the precursor nonwoven material is stretched for about 3-20 of its original length.

6. The softened nonwoven material as claimed in clause 1, characterized in that the precursor nonwoven material is stretched by about 4-15 of its original length.

7. The softened nonwoven material as claimed in clause 1, characterized in that the precursor nonwoven material is stretched using a pulling distance of no more than about 25 inches.

8. The softened nonwoven material as claimed in clause 1, characterized in that the precursor nonwoven material is stretched using a pulling distance of no more than about 10 inches.

9. The softened nonwoven material as claimed in clause 1, characterized in that the precursor nonwoven material is stretched using a pulling distance of no more than about 6 inches.

10. The softened nonwoven material as claimed in clause 1, characterized in that it also comprises one or more additional layers.

11. The softened nonwoven material as claimed in clause 1, characterized in that it also comprises at least one layer bonded with yarn.

12. The softened nonwoven material as claimed in clause 1, characterized in that it further comprises two layers bonded with yarn laminated on both sides of the meltblown fabric.

13. A softened nonwoven material comprising a meltblown fabric, prepared by stretching a precursor nonwoven material in at least one direction using a pulling distance of no more than about 35 inches and multiple pulling phases, the material not softened fabric has a lower head strength and a lower base weight than a similar nonwoven material otherwise prepared using a single pull phase.

14. The softened nonwoven material as claimed in clause 13, characterized in that the pull is achieved in three or more phases.

15. The softened nonwoven material as claimed in clause 13, characterized in that the pulling distance is no more than about 25 inches.

16. The softened nonwoven material as claimed in clause 13, characterized in that the pulling distance is not more than about 10 inches.

17. The softened nonwoven material as claimed in clause 13, characterized in that the pulling distance is not more than about 6 inches.

18. The softened nonwoven material as claimed in clause 13, characterized in that the material is stretched for about 4-20% of its original length.

19. The softened nonwoven material as claimed in clause 13, characterized in that it further comprises one or more additional non-woven layers.

20. The softened nonwoven material as claimed in clause 13, characterized in that it comprises at least one layer bonded with yarn.

21. The softened nonwoven material as claimed in clause 13, characterized in that it further comprises two layers joined by spinning.

22. A non-woven material comprising a blown fabric with thermoplastic melt and at least one woven fabric bonded with thermoplastic yarn, the material has a crushing softness of cup below 2000 grams / mm.

23. The nonwoven material as claimed in clause 22, characterized in that it has a cup crush softness of no more than about 1750 grams / mm.

24. The nonwoven material as claimed in clause 22, characterized in that it comprises two fabrics bonded with thermoplastic yarn on both sides of the meltblown fabric.

25. The nonwoven material as claimed in clause 22, characterized in that the meltblown fabric comprises a polyolefin.

26. The non-woven material as claimed in clause 22, characterized in that the yarn-bound fabric comprises a polyolefin.

27. The nonwoven material as claimed in clause 22, characterized in that the meltblown fabric comprises polypropylene.

28. The non-woven material as claimed in clause 22, characterized in that the yarn-bound fabric comprises polypropylene.

29. A co-melt-spun yarn-bound material bonded with yarn having a basis weight of no more than about 1.5 ounces per square yard and a hydro head strength of at least about 73 mBar.

30. The co-melt-spun yarn-bound material bound with spinning, as claimed in clause 29, characterized in that it has a hydro head resistance of at least about 77 mBar.

31. The spunblown-melt-bonded spin-bonded material, as claimed in clause 29, characterized in that it has a hydro head strength of at least about 82 mBar.

32. The co-melt-spun yarn-bound material bonded with yarn, as claimed in clause 29, characterized in that it has a hydro head resistance of at least about 90 mBar.

33. The co-melt-spun yarn-bound material is spun-bonded, as claimed in clause 29, characterized in that it has a basis weight of no more than about 1.4 ounces per square yard.

34. The co-melt-spun yarn-bound material bonded with yarn, as claimed in clause 29, characterized in that it has a basis weight of no more than about 1.3 ounces per square yard.

35. The co-melt-spun yarn-bound material is spun-bonded, as claimed in clause 29, characterized in that the layers of spin-bonded and melt-blown material comprise a polyolefin.

36. The co-melt-spun yarn-bound material bonded with spinning, as claimed in clause 29, characterized in that the spunblown and meltblown layers comprise a propylene polymer. E S U M E N A non-woven material that includes at least one meltblown fabric is stretched by about 1-35 in at least one direction using a short distance pulling process, to provide a fabric having a softness and an improved liquid barrier in comparison to similar fabrics otherwise prepared using larger jalad distances. The pulling process may include one or multiple phases. When multiple phases are employed, the fabric has an adequate liquid barrier at the lower basis weight.