MXPA97005020A - Non-woven laminate with stretching in transver ladirection - Google Patents

Abstract

The present invention relates to a laminate having a stretch in the transverse direction comprising: a first layer of a polymer fabric bonded with crimpable yarn made of fibers selected from the group consisting of biconstituent and bicomponent fibers; a second layer of an elastomeric polymer, a third layer of a polymer fabric bonded with crimpable yarn made of fibers selected from the group consisting of bicomponent and biconstituent fibers, wherein said layers are joined together by a method that excludes hydroentanglement to form a Laminated with an open bonded pattern having between about 5 and 15 percent joined area, said layers are maintained in an unstretched condition through their production and joined in said laminate, and wherein said laminate is stretched in the transverse direction

Description

NON-WOVEN LAMINATE WITH STRETCHING IN TRANSVERSAL DIRECTION This invention relates to the field of non-woven fabrics for use in medical products, personal care products, garments and outdoor fabrics.

The manufacture of many products of non-woven fabrics can be a very complicated matter involving many different joining and cutting steps. For example, the process for making a surgical gown from non-woven fabrics involves cutting holes for the sleeves and the head in a large piece of material, cutting the material for the sleeves, and then joining the sleeves, usually composed of two pieces. , together with each other and the main body of the gown. Certain robes have reinforced areas (for example elbows) for which additional pieces must be cut, placed and joined. There may be holes for buttons or other form of restraint or closure required on the arms, back or front of the gown. This manufacturing process requires that the pieces of cloth be rotated, turned upside down, folded, etc., many times.

One of the characteristics of certain types of non-woven fabrics which is useful in a variety of applications is elasticity, for example, the ability to stretch and then return to approximately its original size. Such a feature is useful, for example in medical gowns, diapers, training pants, and incontinence products for adults.

Stretchable non-woven fabrics have been produced but generally have been limited to stretch in the machine direction (MD), for example the direction of fabric production. This is useful, but it has been found that many manufacturing processes would benefit from non-woven fabrics which could be stretched in the cross-machine direction (CD). Even though it seems a merely trivial matter, the requirement to repeatedly flip the non-woven fabric during the manufacturing process, for example, a gown, can result in a damaged fabric, increasing maintenance costs and, of course, increasing costs capital for the initial purchase of manufacturing line equipment. Stretch non-wovens in the cross-machine direction would simplify the manufacturing process by eliminating a large number of rotation steps where the stretch material in the machine direction must be turned in order to stretch it in the desired direction.

It is therefore an object of the invention to provide a nonwoven fabric laminate which is stretchable in at least the transverse direction to the machine.

SYNTHESIS The objects of the invention are provided by a multilayer laminate having a stretch in the transverse direction in which the outer layers are fabrics or fabrics of crimped or crimpable spunbonded fabrics which may be of bicomponent fibers and at least an inner layer which is an elastomeric polymer layer. The layers are maintained in an unstretched condition through their production and bonding in the laminate.

DETAILED DESCRIPTION DEFINITIONS As used herein the term "nonwoven fabric or fabric" means a fabric having a structure of individual fibers or threads which are interleaved, but not in a regularly repeatable or identifiable manner as in a finished fabric. Non-woven fabrics or fabrics have been formed by many processes such as, for example, meltblowing processes, spinning processes and carded and bonded tissue processes. JE1 basis weight of non-woven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and useful fiber diameters are usually expressed in microns. (Note that to convert osy to gsm, you must multiply osy by 33.91).

As used herein the term "microfibers" means fibers of small diameter having an average diameter of no more than about 50 microns, for example, having an average diameter of from about 0.5 microns to about 50 microns, or more particularly, the microfibers can have an average diameter of from about 2 microns to about 40 microns. The diameter of for example, a polypropylene fiber given in microns, can be converted to denier by the square, and multiply the result by 0.00629, therefore, a polypropylene fiber of 15 microns has a denier of about 1.42 (152 x 0.00629 = 1.415).

As used herein, the term "spunbonded fibers" refers to fibers of small diameter which are formed by extruding the melted thermoplastic material as filaments of a plurality of usually circular and thin capillary vessels of a spinner organ having the diameter of the extruded filaments then being reduced rapidly as indicated, for example, in the patent of the United States of North America no. 4,340,563 issued to Appel et al., And in the United States of America patent no. 3,692,618 issued to Dorschner et al., In the United States of America patent no. 3,802,817 issued to Matsu i et al., In the patents of the United States of North America nos. 3,338,992 and 3,341,394 issued to Kinney, in the patent of the United States of North America no. 3,502,763 granted to Hartman, in the patent of the United States of North America no. 3,502,538 granted to Levy, and in the patent of the United States of North America no. 3,542,615 granted to Dobo and others. Spunbond fibers are generally continuous and larger than 7 microns, more particularly, often between about 10 and 30 microns.

As used herein, the term "fibers formed by meltblown" means fibers formed by extruding a melted thermoplastic material through a plurality of usually circular and thin capillary matrix vessels such as melted threads or filaments into a gas stream ( for example air) at high speed which attenuates the filaments of the melted thermoplastic material to reduce its diameter, which can be a diameter of icrofiber. Then, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a fabric of meltblown fibers uncluttered in a random fashion. Such process is described, in for example, the patent of the United States of America no. 3,849,241 granted to Butin. The meltblown fibers are usually microfibers which are generally smaller than 10 microns in diameter.

As used herein, the term "polymer" generally includes but is not limited to, homopolymers, copolymers, such as block, graft, random and alternating copolymers, terpolymers, etc., and mixtures and modifications of. the same. In addition, unless specifically limited in another way, the term "polymer" will include all possible geometric configuration of the material. These configurations include, but are not limited to, isotactic, syndiotactic, atactic and random symmetries.

As used herein, the term "machine direction" or "MD" means the length of a fiber as it is produced. The term "cross machine direction", "cross direction" or "CD" means across the width of the fabric, for example, an address generally perpendicular to the machine direction.

As used herein, the term "bicomponent fibers" refers to fibers which have been formed from at least two extruded polymers from separate extruders but spun together to form a fiber. The polymers are arranged in distinct zones essentially permanently positioned across the cross section of the bicomponent fibers and extending continuously along the length of the bicomponent fibers. The configuration of such bicomponent fiber can be, for example, a pod / core arrangement where one polymer is surrounded by another or can be a side-by-side arrangement or an arrangement of "islands in the sea". The bicomponent fibers are shown in U.S. Patent No. 5,108,820 issued to Kaneko et al., In U.S. Pat. No. 5,336,552 issued to Strack et al., And in European patent no. 0586924. For two bicomponent fibers, the polymers may be present in proportions of 75/25, 50/50, 25/75 or any other desired proportions.

As used herein the term "biconstituent fibers" refers to fibers which have been formed from at least two extruded polymers 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 non-continuous along the entire length of the fiber, instead of this usually forming fibrils which start and end in a random way. 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 patent no. 5,108,827 granted to Gessner. Bicomponent and biconstituent fibers are also discussed in the textbook "Mixtures and Polymer Compounds" by John A.

Manson and Leslie H. Sperling, copyright 1976 by Plenun Press, a division of Plenum Publishing Corporation of New York IBSN 0-306-30831-2, pages 273 to 277.

As used herein, the term "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 "misibility" and the "inability" are defined as mixtures that have negative and positive values, respectively, for the free energy of mixing. In addition, "compatibilization" is defined as the process for modifying the interfacial properties of an immiscible polymer mixture in order to constitute an alloy.

As used herein the terms "tapered" or "stretch and tape" refers interchangeably to a method for stretching a non-woven fabric, generally in the machine direction to reduce its width in a controlled manner to a desired amount. The controlled stretching can take place under a cold temperature, room temperature or higher temperatures and an increase in the dimension in the overall dimension is limited in the direction in which it is being stretched to the elongation required to break the fabric, which in the Most cases are around 1.2 to 1.4 times. When it relaxes, the tissue retracts to its original dimensions. Such process is described, for example, in the patent of the United States of North America no. 4,443,513 granted to Meitner and Notheis and another in the patent of the United States of North America no. 4,965,122 granted to Mor an.

As used herein, the term "softening and constricting" means the stretching and constriction carried out without addition of heat of the material as it is stretched.

As indicated herein, the term "narrowable material" means any material that can be constricted.

As used herein the term "tapered material" refers to any material which has been constricted in at least one dimension by the process such as, for example, pulling or bending.

As used herein the term "recover" refers to a contraction of a stretched material upon the termination of the pressing force followed by-the stretching of the material by the application of the pressing force. For example, if a material having an unpressed and relaxed length of one inch is stretched 50 percent by stretching to a length of one and a half inches the material will have been lengthened by 50 percent and will have a stretched length that is 150 percent of its relaxed length If this exemplary stretched material contracts, ie a length of one and one tenth of an inch is recovered after the release of the stretching and pressing force, the material will have recovered 80 percent (0.4 inches) of its elongation.

As used herein, the term "squeeze" means a process applied to a material reversibly constricted to extend it to its original pre-stretched dimensions by applying a stretching force in a direction transverse to the machine or longitudinal which causes it to recover to inside of at least about 50 percent of its dimensions reversibly narrowed with the release of the stretching force.

As used herein, the term "stitched" means, for example, the firing of the material as set forth in the United States of America patent no. 4,891,957 issued to Strack et al. Or in the patent of the United States of North America no. 4,631,933 awarded to Carey, Jr.

As used herein the term "medical product" means surgical gowns and drapes, face masks, head covers, shoe covers, wound dressings, bandages and sterilization wraps.

As used herein, the term "personal care product" means diapers, baby bibs, training pants, absorbent underwear, incontinence products for adults, cloths and products for women's hygiene.

As used herein, the term "protective cover" means a cover for vehicles such as cars, trucks, boats, airplanes, motorcycles, bicycles, golf carts, etc. , covers for equipment frequently left outdoors or outdoors such as grills, garden and meadow equipment (mowers, broken cultivators, etc.) and meadow furniture, as well as floor coverings, table and table covers for area of lunch As used herein, the term "weather cloth" means a cloth which is primarily, even if not exclusively used outdoors. Outdoor fabrics include a fabric used in protective coverings, a tow / camping fabric, tarpaulins, tarpaulins, pavilions, tents, agricultural fabrics, (eg, row covers), and outdoor apparel such as decks of head, industrial work clothes and covers, pants, shirts, coats, gloves, socks, shoe covers and the like.

TEST METHODS Cup of melted flow. The melt flow rate (MFR) is a measure of the viscosity of a polymer. The MFR is expressed as the weight of material flowing from a capillary vessel of known dimensions under a specified load or shear rate for a measured period of time and is measured in grams / 10 minutes at 230 ° C according to, for example , the ASTM standard proves 1238, condition E.

Grip Tension Test. The Grip Tension Test is a measure of a resistance to the breaking and lengthening or tension of a fabric when it is subjected to the unidirectional tension between two clamps. The values for the grip strength and the elongation of grip are obtained using a specified fabric width, a clamp width and a constant extension cup. The sample is as wide as the clamps and as long as the distance between the clamps to give representative results of the effective strength of the fibers in the embraced width combined with the additional strength contributed by the adjacent fibers in the fabric. This simulates very similarly fabric tension conditions in actual use. The results are expressed as pounds to break and percentage to stretch to break. The total energy can also be expressed as well as energy to break. The upper numbers indicate a more stretchable or stronger fabric.

Cyclic test: In the cyclic test a material is taken at a fixed extension or fixed load to develop a graphical representation of the results, with the load on the axis and the elongation on the x axis. This graph gives a curve with an area down there called the "Total Absorbed Energy" or "TEA". The proportion of the curves of total energy absorbed for a sample for several cycles is a value independent of the material, the base weight and the sample width that can be compared to other samples.

DETAILED DESCRIPTION The laminate fabric of this invention comprises a layered construction of at least one layer of an elastomeric thermoplastic polymer layer sandwiched between two layers of nonwoven fabric bonded by filament spinning or crimped fiber. Spunbond fibers can be bicomponent.

The "elastomeric thermoplastic polymer layer useful in the practice of this invention may be that made of styrene-block copolymers, polyurethanes, polyamides, copolyesters, ethylene vinyl acetate (EVA) and the like and may be composed of a meltblown fabric, a yarn-bonded fabric, a film or a foam layer and can itself be composed of one or more thinner layers of elastomeric thermoplastic polymer Generally, any elastomeric fiber, film or foam-forming resins or mixtures thereof can be used to form the non-woven fabrics of the elastomeric fibers, the elastomeric film or the elastomeric foam.

Styrenic block copolymers include styrene / butadiene / styrene block copolymers (SBS), styrene / isoprene / styrene block copolymers (SIS), styrene / ethylene-propylene / styrene block copolymers (SEPS), block copolymers of styrene / ethylene-butadiene / styrene (SEBS). For example, useful elastomeric fiber-forming resins include block copolymers having the general formula ABA 'or AB, wherein A and A' are each an end block of a thermoplastic polymer which contains a styrenic group such as a poly (vinylarene) and wherein B is a middle block of elastomeric polymer such as conjugated diene or a lower alkene polymer. The block copolymers of type A-B-A 'may be different or the same thermoplastic block polymers for blocks A and A', and the block copolymers present are intended to encompass linear, branched and radial block copolymers. In this aspect, the radial block copolymers can be designated (A-B) p-X, wherein X is a polyfunctional atom or molecule and in which each (A-B) -radial of X in a manner that A is an end block. The radial block copolymer, X can be a molecule or a polyfunctional organic or inorganic atom and n is an integer having the same value as the functional group originally present in X. This is usually at least 3 and is often 4 or 5. , but it is not limited to this. Therefore, in the present invention, the term "block copolymer", and particularly a block copolymer "AB-A '" and "AB", is intended to encompass all block copolymers having such alate blocks and thermoplastic blocks as discussed above, which can be extruded (for example by melt blowing) and without limitation as to the number of blocks.

The patent of the United States of America no. 4,663,220 issued to Wisneski et al. Describes a fabric including microfibers comprising at least about 10 percent by weight of a block copolymer ABA 'wherein "A" and "A" 1 are each a thermoplastic end block which comprises a styrenic group and wherein "B" is a middle block of elastomeric poly (ethylene-butylene), and from more than zero percent by weight to about 90 percent by weight of a polyolefin which when mixed with the copolymer of ABA 'block and subjected to an effective combination of high temperature and high pressure conditions, it is adapted to be extruded, in a mixed form with block copolymer AB-A'. The polyolefins useful in isnesky and others may be polyethylene, polypropylene, polybutene, ethylene copolymers, propylene copolymers, butene copolymers, and mixtures thereof.

Commercial examples of such elastomeric copolymers are, for example, those known as KRATON® materials which are available from the Shell Chemical Company of Houston, Texas. KRATON® block copolymers are available in several different formulas, a number of which are identified in U.S. Patent 4,663,220 incorporated herein by reference. A particularly suitable elastomeric layer can be formed of, for example, poly (styrene / ethylene-butylene / styrene) block copolymer available from Shell Chemical Company of Houston, Texas under the trade designation KRATON®G-1657.

Other exemplary elastomeric materials which can be used to form an elastomeric layer include polyurethane elastomeric materials such as, for example, those available under the trademark ESTAÑE® of B. F. Goodrich & Co., elastomeric polyamide materials such as, for example, those available under the trademark PEBAX® from Rilsan Company, and elastomeric polyester materials such as, for example, those available under the trade designation HYTREL® from EI DuPont de Nemours &; Company The formation of a non-woven elastomeric polyester elastomeric fabric is described in, for example, U.S. Patent 4,471,949 issued to Morman et al. And incorporated herein by reference.

The elastomeric layers may also be formed of elastomeric ethylene copolymers and at least one vinyl monomer such as, for example, vinyl acetates, unsaturated aliphatic monocarboxylic acids, and the esters of such monocarboxylic acids. The elastomeric copolymers and the formation of the elastomeric non-woven fabrics of those elastomeric copolymers are described in U.S. Patent No. 4,803,117. Elastomeric meltblown thermoplastic fabrics are particularly useful for those fiber composites of a material such as that described in U.S. Patent No. 4,707,398 issued to Boggs et al., U.S. Patent No. 4,741,949 issued to Morman et al., And United States Patent No. 4,663,220 issued to Isneski et al. In addition, the elastomeric meltblown thermoplastic polymer layer may itself be composed of one or more thinner layers of the elastomeric meltblown thermoplastic polymer which have been deposited in sequence one above the other or have been laminated together by the methods known to those skilled in the art.

The thermoplastic copolyester elastomers include copolyethers having the general formula: 0 0 0 0 I I I I H- ([0-G-0-C-C6lH4-C]? - [O (CH2) ß-0-C-C6H4-C]) _-0- (CH2) b0H wherein "G" is selected from the group consisting of poly (oxyethylene) -alpha, omega-diol, poly (oxypropylene) -alpha, omega-diol, poly (oxytetramethylene) -alpha, omega-diol and "a" and "b" are positive integers including 2, 4, and 6, "x", "y" and "z" are positive integers including 1-20. Such materials generally have an elongation at break of from about 600 percent to 750 percent when measured in accordance with ASTM D-638 and a melting point of from about 350 ° F to about 400 ° F (176 ° C). 205 ° C) as measured in accordance with ASTM D-2117. Commercial examples of such copolyester materials are, for example, those known as ARNITEL® commercially available from Akzo Plastics from Amhem, Holland and now available from DSM's Sittard, Holland, or those known as HYTREL® which are available from E.I. Dupont de Nemours of Wilmington, Delaware.

Examples of suitable foams include those produced by General Foam Corporation of Paramus, New Jersey. Such foams are polyurethane foams under the trade designation "Series 4000". Such foams are described in U.S. Patent 4,761,324 issued to Rautenberg and others in column 6, lines 53-68, incorporated herein by reference.

An elastomeric meltblown layer may be joined with stitches in accordance with the patent of the United States of America no. 4,891,957 granted to Strack et al. Firing imparts strength and durability to the baked product and the bonding of this form in the present invention is believed to impart an abrasion resistance to the laminate. Although stitching is generally used to join two or more materials together in the embodiment of the present invention, the elastomeric meltblown layer is stitched together and is then used in the manufacture of the laminate.

The spunbonded nonwoven fabric is produced by a method known in the art and is described in a number of references cited above. Briefly, the spinning process generally uses a hopper which supplies a polymer to a heated extruder. The extruder supplies a melted polymer to a spinning organ wherein the polymer is fiberized as it passes through the fine openings usually arranged in one or more rows in the spinning organ, forming a curtain of filaments. The filaments are usually cooled with an air at low pressure, pulled, usually pneumatically, and placed on a moving foraminous mat, a band or a "forming wire" to form the non-woven fabric.

The fibers produced in the spinning process are usually in the range of from about 10 to about 30 microns in diameter, depending on the process conditions and the desired end use for the fabrics to be produced from such fibers. . For example, increasing the molecular weight of the polymer or lowering the processing temperature results in large diameter fibers. Changes in the cooling fluid temperature and the pneumatic pulling pressure can also affect the diameter of the fiber.

The polymers useful in the spinning process generally have a melt process temperature of between 175 ° to 320 ° C and one cup of melt flow, as defined above, in the range of about 10 to about 150. , more particularly between about 10 and 50. Examples of suitable polymers include polypropylenes, polyethylenes and polyamides.

The bicomponent fibers can also be used in the practice of this invention. The bicomponent fibers are commonly made of polypropylene and polyethylene arranged in a sheath / core configuration, of "islands in the sea" or side by side. Suitable commercially available materials include the polypropylene designated PP-3445 from Exxon Chemical Company of Baytown, Texas, ASPUN® 6811A and 2553 linear low density polyethylene from Dow Chemical Company of Midland, Michigan, high density polyethylene 25355 and 12350 from Dow Chemical Company, DURAFLEX® DP8510 polybutylene from the Shell Chemical Company of Houston, Texas, and ethylene n-butyl acrylate from ENATHENE® 720-009 from Quantum Chemical Corporation of Cincinnati, Ohio.

Certain biconstituent fibers can also be used in the practice of this invention. Mixtures of polypropylene copolymer and polybutylene copolymer in a 90/10 mixture have been found effective. Any other mixture will also be effective as long as it can be spun and provide crimped or crimpable fibers.

The fibers of the spunbonded layer used in the practice of this invention should be crimped or crimpable since the inventors have found that the crimped fiber fabrics when laminated to an elastomeric meltblown layer have sufficient "give" to stretch to the largest dimension without breaking.

The curling of a fiber joined with spinning can be achieved through a number of methods. One method is to produce a fabric knitted together on a forming wire and then to pass the fabric between two drums or rolls with different surfaces. The rollers mix the fibers of the fabric as they pass between them and produce the desired curl. Another method to create fiber curl is to mechanically stretch each fiber.

When fibers joined with bicomponent yarn are used in the practice of this invention, curling can be achieved by heating the fibers. The two polymers that make up the bicomponent fibers can be selected to have different coefficients of expansion and with the heating to create curls in the fibers. This heating can be done after forming the fabric on the forming wire at a temperature of from about 43 ° C to a temperature lower than that of the melting point of the lower melting component of the fibers. The heating can alternatively be done by dropping the fibers from the spinning organ to the forming wire as taught in European patent application no. 586, 924 granted to Pike and others, which was published on March 16, 1994. In the Pike process, the heated air in the range of from about 43 ° C to a temperature lower than that of the melting point of the component The lower melt of the fibers was erected to the fibers as they fell, causing the two polymers to expand differently from one another and the fiber will curl.

The laminated fabric of this invention can be made by first depositing on a forming wire a layer of crimped spunbonded fibers. A layer of the elastomeric meltblown fibers is deposited on the top of the fibers bonded with crimped yarn. Finally, another layer of crimped spunbonded fibers is deposited on the meltblown layer and this layer is usually preformed. There can be more than one layer of melted elastomeric blowing fibers. None of the layers are stretched in any direction during the production process of the laminate, including the joining step.

Alternatively, all the layers can be produced independently and put together in a separate lamination step. If this method of manufacture is chosen, it is still important that the layers do not stretch during the manufacture of the laminate.

The requirement that the fabric not be stretched during manufacture in a laminate means that the fabric is not subjected to any additional or excessive stretching force beyond that normally provided by the type of mechanism that is usually used to produce the laminate, for example the rollers and reels which move the fabric along the process path from prelamination to post-inaction. The fabric of this invention does not require being narrowed-stretched, smoothed with narrowing or not being tapered to provide the desired stretch properties.

After the addition of the last layer of the crimped spunbonded fibers, the layers are joined to produce the laminate. The joint can be made thermally such as by air bonding or knit bonding using pattern calendering rolls.

The bonding by air or " " is discussed in European patent application no. 586,924 issued to Pike et al. And is a process of joining a non-woven bicomponent fiber fabric which is at least partially wound around a perforated roller which is enclosed in a cover. The air which is hot enough to melt one of the polymers from which the fibers are made is forced from the cover, through the fabric and to the perforated roller. The air speed is between 100 and 500 feet per minute and the dwell time can be as long as 6 seconds. The melting and resolidifación of the polymer provides the union. Since air binding requires the melting of at least one component to achieve bonding, it is restricted to bicomponent fiber fabrics.

The thermal point union has been developed using calendering rolls with various patterns. An example is the Hansen Pennings pattern expanded with about 15% area bonded to about 100 unions / square inch as taught in the United States of America patent no. 3,855,046 awarded to Hansen and Pennings. Another common pattern is a diamond pattern with repetitive and slightly off-center diamonds.

The bonding of the laminate may alternatively be made in ultrasonic form, through the adhesive printing bond, by any other method known in the art to be effective except the hydroentanglement method.

The fabric of this invention can be treated, either the individual fibers before lamination, or the complete fabric after lamination, with various chemicals according to known techniques to give them properties for specialized uses. Such treatments include chemical repellents, chemical softeners, chemical fire retardants, chemical oil repellents, antistatic agents and mixtures thereof. The pigments may also be added to the fabric as a post-bonding treatment or alternatively added to the polymer of the desired layer prior to fiberization.

It has been found that the fabric of this invention is stretched in the transverse direction to the machine by at least about 100 percent.

The fabric of this invention can be used in personal care products, medical products and fabrics for outdoor use. It is also believed that this fabric will be useful in automotive applications such as car head linings.

The properties of several laminates were compared. These laminates are described below where the samples are laminates made according to the invention and the control is not.

Control .

The polypropylene fibers spun in both layers facing outward, with an elastomeric meltblown layer therebetween.

The melting of elastomeric melt was made from KRATON® G-2740 from Shell and had a basis weight of approximately 61 grams per square meter.

The fiber bonded with spinning was Exxon PD-3445 polypropylene extruded through 0.6 millimeter orifices at a rate of 0.7 grams / hole / minute (ghm) having a basis weight of 22 grams per square meter for each facing layer. The fabric was bonded at a temperature of 291 ° F using the thermal calender bond with a 5% spiral pattern. In none of the layers did it stretch during production or bonding.

Sample 1 The fibers bonded with yarn in both layers facing outwardly with an elastomeric meltblown layer therebetween.

The elastomeric meltblown was made of KRATON® G-2740 from Shell and had a basis weight of approximately 61 grams per square meter.

The spunbonded fabric was produced from a spun pack by having alternate rows of fibers to produce a mixture of different types of fibers in a fabric or woven layer resulting in a crimpable fabric. One row of fibers was Exxon PD-3445 polypropylene and the next row was a mixture of 90 percent Shell polypropylene copolymer and 10 percent by weight Shell Duraflex® polybutylene copolymer. The polypropylene copolymer had an ethylene content of 3.2 percent by weight and the polybutylene copolymer had an ethylene content of 6 percent by weight. All polymers were extruded through holes of 0.6 mm at a rate of 0.5 grams / hole / minute (ghm) and having a basis weight of 34 grams per square meter for each front layer. The fabric was bonded at a temperature of 291 ° F using a thermal calender joint with a 5% spiral pattern. None of the layers were stretched during production or bonding.

Sample 2 The fibers bonded with biconstituent yarn in both outer face layers with an elastomeric meltblown layer in the middle.

The elastomeric meltblown was made of KRATON® G-2740 from Shell and had a basis weight of approximately 61 grams per square meter.

Spunbonded was a bicomponent blend of 90 percent by weight of polypropylene copolymer and 10 percent by weight of copolymerq of polybutylene as described in sample 1 extruded through 0.6 mm holes at a 0.7 gram cup / hole / minute (ghm) and having a basis weight of 34 grams per square meter for each face layer to provide a crimpable fabric. The fabric was bonded at a temperature of 270 ° F using thermal calendering bond with a square pattern of bond area of 5%. None of the layers were stretched during production or bonding.

Sample 3 The fibers are bonded with biconstituent yarn in both layers facing outwards with an elastomeric meltblown layer in between.

The elastomeric meltblown was made from Shell's KRATON® G-2740 and had a basis weight of approximately 61 grams per square meter.

Spunbonded was a biconstituent mixture of a polypropylene copolymer of 90 percent by weight and 10 percent by weight of polybutylene copolymer as described in mixture 1 and extruded through 0.6 millimeter orifices to a 0.53 cup. grams / hole / minute (ghm) and having a basis weight of 24 grams per square meter for each face layer to provide a crimpable fiber. The fabric was bonded at a temperature of 291 ° F using the thermal calender bond with a square area pattern of 5% binding. None of the layers were stretched during production or bonding.

Sample 4 The fibers bonded with bicomponent yarn curled in both layers facing outward with an elastomeric melt blown layer in the middle.

The melted elastomeric blow was made from KRATON® G-2740 from Shell and had a basis weight of approximately 61 grams per square meter.

The bond with crimped yarn was a side-by-side fiber of Exxon PD-3445 polypropylene and Dow Aspun8 6811 A polyethylene extruded through 0.6 mm holes at a rate of 0.65 grams / hole / minute (ghm) and having a basis weight of 27 grams per square meter for each face layer. The fabric was bonded at a temperature of 258 ° F using the binding through air. None of the layers were stretched during production or bonding.

Sample 5 The fibers bonded with bicomponent yarn curled in both layers facing outward with an elastomeric meltblown layer in the middle.

The elastomeric meltblown layer was made of KRATON® G-2740 from Shell and had a basis weight of approximately 61 grams per square meter.

The bond with crimped yarn was a side-by-side fiber of Exxon PD-3445 polypropylene and Dow Aspun®6811A polyethylene extruded through holes of 0.6 millimeters at a rate of 0.65 grams / hole / minute (ghm) having a basis weight of 13 grams per square meter for each face layer. The fabric was bonded at a temperature of 258 ° F using the binding through air. None of the layers were stretched during production or bonding.

The laminates described above were subjected to tests for cross-machine direction stretching and recovery carried out on a Sintech Instron machine. A sample of three inches wide was used and the stretching speed was 300 mm / min for the peak load and the peak voltage. The peak elongation or tension is expressed in percent. The peak load is expressed in grams. The elongation of the test cycle is expressed in percent. The first cycle of loading in the elongation cycle (A) is expressed in grams. The properties of the samples are indicated in table 1.

Table 1 Voltage Load Cycle of A Peak Peak Lengthening Control 79 3690 50 2690 Sample 1 130 3682 80 3720 Sample 2 190 1420 125 1210 Sample 3 125 2980 75 2230 Sample 4 101 2970 55 2290 Sample 5 25 1060 50 1420 The inventors believe that the data for the crimped bicomponent fibers (Samples 4 and 5) will be improved with a different bonding method even when the cyclic test data is favorable. The method used, binding through air, provides many points together and probably results in a loss of stretchability, therefore, the union through air is not preferred. The other samples and the control did not use the binding through air.

The data indicates that the fabric of this invention provides excellent cross-machine direction stretch at lower loads than for a non-crimpable polypropylene spun bond. This is a very useful property which simplifies the manufacture of many products such as diapers and surgical gowns, which are made of this fabric.

Claims (20)

1. A laminate having a stretch in the transverse direction comprising: a first layer of a polymer fabric bonded with a crimpable yarn; a second layer of an elastomeric polymer; a third layer of a polymer fabric bonded with crimpable yarn; wherein said layers are joined together by a method excluding hydroentanglement to form a laminate and wherein said layers are maintained in an unstretched condition through their production and bonding in a laminate.

2. The laminate as claimed in clause 1 characterized in that each spunbonded layer can independently be selected from the group consisting of crimpable bicomponent fibers, crimpable biconstituent fibers and rizables mixtures of different types of fibers.

3. The laminate as claimed in clause 1 characterized in that said layers are joined to each other in a non-stretched condition by a method selected from the group consisting of thermal bonding, ultrasonic bonding, printing bonding and adhesive bonding.

4. The laminate as claimed in clause 1 characterized in that said elastomeric polymer layer is selected from the group consisting of elastomeric meltblown fabrics, elastomeric yarn bonded fabrics, elastomeric films and elastomeric foams.

5. The laminate as claimed in clause 4 characterized in that said layer of elastomeric polymer is composed of one or more thinner layers.

6. The laminate as claimed in clause 4, characterized in that said elastomeric layer is joined with a point before incorporation. inside the laminate.

7. The laminate as claimed in clause 4 characterized in that the elastomeric layer comprises at least about 10 percent by weight of a block copolymer ABA 'wherein "A" and "A"' are each an end block thermoplastic which comprises a styrenic group and wherein "B" is a middle block of elastomeric poly (ethylene-butylene), and from more than 0 percent by weight to about 90 percent by weight of a polyolefin which is then mixed with the ABA 'block copolymer and subjected to an effective combination of high temperature and high pressure conditions, is adapted to be extruded, in a form blended with the ABA' block copolymer.

8. The laminate as claimed in clause 4 characterized in that said polymer of elastomeric polymer layer is selected from the group consisting of styrene copolymers, polyurethanes, polyamides, copolyesters, copolyesters, ethylene vinyl acetate and esters.

9. The laminate as claimed in clause 5 characterized in that said polymer is a mixture of a block copolymer A-B-A 'and polypropylene.

10. The laminate as claimed in clause 5 characterized in that said elastomeric polymer layer comprises elastic fibers of a block copolymer.

11. The laminate as claimed in clause 10 characterized in that said polyetherester has the general formula: 0 0 0 0 IIII H - ([0-G-0-C-C6H4-C]? - [0 (CH2) a- 0-C-C6H4-C] y) z-0- (CH2) bOH wherein "G" is selected from the group consisting of poly (oxyethylene) -alpha, omega, diol, poly (oxypropylene) -alpha, omega-diol, poly (oxytetramethylene) -alpha, omega, diol and "a" and "b" are positive integers selected from the group consisting of 2, 4 and 6 and "x", "y" and "z" are positive integers selected from the group consisting of numbers between 1 and 20.

12. The laminate as claimed in clause 1 characterized in that at least one layer has been treated with a chemical selected from the group consisting of water repellent chemicals, chemical softeners, fire retardant chemicals, chemical oil repellents and mixtures of the same.

13. The laminate as claimed in clause 1 characterized in that said spunbond woven fabrics are composed of bicomponent fibers in a sheath / core arrangement with polypropylene as the core and the polyethylene as the sheath.

14. The laminate as claimed in clause 1 characterized in that said layers have base weights of between about 0.25 and 3 ounces per square yard.

15. The laminate as claimed in clause 1 characterized in that it is present in a product selected from the group consisting of medical products, personal care products and outdoor fabrics.

16. The laminate as claimed in clause 15 characterized in that said product is a product for personal care and said personal care product is a diaper.

17. The laminate as claimed in clause 15 characterized in that said product is a product for personal care and said personal care product is a product for the hygiene of women.

18. The laminate as claimed in clause 15 characterized in that said product is a medical product and said medical product is a surgical gown.

19. The laminate as claimed in clause 15 characterized in that said product is a medical product and said medical product is a mask for the face.

20. The laminate as claimed in clause 15 characterized in that said product is a medical product and said medical product is a cleaner.