MXPA98008631A - Fixed fabric with high resistance of polymers of flow rate of melting to - Google Patents

Abstract

The present invention relates to a spunbonded nonwoven fabric which has superior strength characteristics than conventional fabrics and yet is still comparably soft. The fabric is a laminate having a fabric made of a higher melt flow rate polyolefin polymer and a lower melt flow rate polymer. The spunbonded laminate fabric of this invention may have thereon a meltblown nonwoven fabric layer. The laminate produced according to this invention has a strength which is at least 10% greater than that of a comparable fabric made with the higher melt flow rate polymer fabric. The non-woven fabric of this invention can be used in products such as, for example, garments, personal care products, medical products, protective covers and weathering fabrics.

Description

i FIXED FABRIC OF HIGH RESISTANCE OF RATE POLYMERS OF HIGH MELTED FLOW BACKGROUND OF THE INVENTION This invention relates generally to a woven or woven fabric which is formed of spunbonded fibers of a thermoplastic resin and laminates using such fabric as a component.

Thermoplastic resins have been extruded to form fibers, fabrics and fabrics for a number of years. The thermoplastics for this application are polyolefins, particularly polypropylene. Other materials such as polyesters, polyetheresters, polyamides and polyurethanes are also used to form fabrics joined by spinning.

Non-woven fabrics or fabrics are useful for a wide variety of applications such as diapers, feminine hygiene products, towels, and recreational or protective fabrics. The non-woven fabrics used in these applications are often in the form of laminates such as spin-bonded / spin-bonded (SS) laminates or spin-bonded / spin-bonded (SMS) laminates.

One of the desired characteristics of non-woven fabrics is that they are as soft as possible. Previously, the improved softness had generally involved an exchange with other desirable tissue properties such as tensile strength. For example, polyethylene fabrics are very soft, but they are also very weak.

It is an object of this invention to provide a nonwoven fabric or fabric which is softer than that conventionally produced but which has comparable strength characteristics.

SYNTHESIS OF THE INVENTION The soft and strong non-woven spunbonded polyolefin fabric is provided which is a multilayer laminate of a first high melt flow polymer fiber fabric and a second low melt flow polymer fabric or fabric. . The polymer fabric of low melt flow polymer produces a polyolefin polymer having a melt flow rate of below 50 grams / 10 minutes according to ASTM D-1238-90b, condition L. Higher melt flow polymer fibers are produced from a polyolefin polymer having a melt flow rate of at least 50 grams / 10 minutes according to ASTM D-1238-90b, condition L wherein the Polyolefin polymer is initially produced as a reactive granule through the use of a Ziegler-Natta catalyst with a melt flow rate of below 50 grams / 10 minutes at 230 ° C subsequently modified by a method such as the addition of up to 1000 ppm of peroxide, the addition of up to 5 percent by weight of an organometallic compound and the addition of up to 5 percent by weight of a transition metal oxide. This treatment increases the melt flow rate of the polymer by a factor of at least two. Such a laminate has a tensile strength of at least 10 percent or more than a similar laminate made without a superior melt flow rate fabric but instead with a weave of the same type as that of the second weave. . The fabric of this invention may also have several layers placed between the first and second weaves.

The nonwoven fabric of this invention can be used in products such as, for example, garments, personal care products, medical products, protective coverings, outdoor fabrics.

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 an identifiable manner as in a woven fabric. Non-woven fabrics have been formed from many processes such as, for example, meltblowing processes, spinning processes, and carded and bonded tissue processes. The basis weight of non-woven fabrics is usually expressed in ounce 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 from ounces per square yard to grams per square meter, multiply ounces per square yard by 33.91).

As used herein the term "microfibers" means small diameter fibers having an average diameter of no more than about 75 microns, for example having an average diameter of from about 0.5 microns to about 50 microns, or more particularly, microfibers They can have an average diameter of from about 2 miera to about 40 microns.The diameter of, for example, a polypropylene fibr given in microns, can be converted to denies by squaring, and multiplying the result by 0.00629, by therefore, a polypropylene fiber of 15 microns has a denier of around 1.42 (152 x 0.00629 = 1.415).

As used herein, the term "spun bonded 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 fine capillaries of a spinner with the diameter of the extruded filaments then being rapidly reduced, such as, for example, in U.S. Patent No. 4,340,563 issued to Appel et al., and in U.S. Patent No. 3,692,618 issued to Dorschner and others, in the patent of the United States of North America No. 3,802,817 granted to Matsuki and others, and in those of the United States of North America No. 3,338,992 and 3,341,344 granted to Kinney, in the United States of America No. 3,502,763 and 3,542,615 granted Dobo and others. Spunbond fibers are generally continuous and longer than 7 microns, more particularly these are usually between about 15 and 50 microns.

As used herein, the term "melt blown fibers" means fibers formed by extruding a melted thermoplastic material through a plurality of capillary, usually circular and fine matrix vessels such as melted filaments or filaments into a gas stream ( for example, air), at high speed which attenuates the filaments of melted thermoplastic material to reduce its diameter, which can be to a microfiber diameter. Then, the meltblown fibers are carried by the high velocity gas stream and the collector surfaces are deposited to form a meltblown fiber fabric disbursed to the yarn. Such a process is described, for example, in the United States patent. from North America No. 3,849,241 awarded to Buti. Melt-blown fibers are microfibers which are generally smaller than 10 microns in diameter. The meltblown term used herein is intended to encompass the melt spray process.

As used herein, the term "polymer" generally includes but is not limited to homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc. and mix and modifications thereof. In addition, unless specifically limited otherwise, the term "polymer" included every possible geometric configuration of the material. These configurations include, but are not limited to, isotactic, syndiotactic and random symmetry.

As used herein, the term "bicomponent fibers" refers to fibers which have formed at least two polymers extruded from separate extruders or spun together to form a fiber. The polymers are arranged in distinct zones essentially essentially positioned across the cross section of the bicomponent fibr and extend continuously along the length of the bicomponent fibers. The bicomponent fiber configuration 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 taught in U.S. Patent No. 5,108,820 issued to Kaneko others, in U.S. Patent No. 5,336,552 issued to Strack et al., And European patent 0586924. The polymers can be present in proportions of 75/25, 50/50, 25/75 or 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 as 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 along the length of the fiber, instead of this, usually forming fibrils that start and end at random. Biconstituent fibers are sometimes referred to as multi-constituent fibers. Fibers of this general type are discussed in, for example, United States Patent No. 5,108,827 issued to Gessner. Bicomponent and biconstituent fibers are also discussed in the text Polymer and Compound Mixtures by John A. Manson and Leslie H. Sperling, copyright 1976 by Plenum Press, a division of Plenum Publishing Corporation of New York, IBSN 0-306 -30821-2, 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 "miscibility" and the "immiscibility" are defined as mixtures having negative and positive values, respectively, for the free energy of mixing. In addition, "compatibilization" is defined as the process of modifying the interfacial properties of an immiscible polymer mixture in order to make an alloy.

As used herein, the term "prodegradant" refers to materials which promote the degradation of the melt flow of a polymer from a low melt flow rate to a higher melt flow rate.

As used herein, the term "garment" means any type of garment which may be worn. This includes work clothes and coveralls, undergarments, pants, shirts, coats, gloves, socks and the like.

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

As used herein, the term "personal care product" means diapers, underpants, absorbent undergarments, adult incontinence products, and women's hygiene products.

As used herein, the term "protective cover means a cover for vehicles such as trucks, boats, airplanes, motorcycles, bicycles, golf cart, etc., covers for equipment that is often left outdoors such as grills, equipment patio and garden (mowers, rocillilladoras, etc.) and furniture for meadow, as well as covers for floor, tablecloths and covers for picnic area.

As used herein, the term "outer fabric" means a fabric which can be used primarily, even if not exclusively, in the open. Outdoor fabrics include fabrics used in protective coverings, towing cloth / tents, tarpaulins, pavilions, tents, agricultural fabrics and outdoor clothing such as head coverings, industrial workwear and overalls, pants, shirts, coats, gloves, socks, shoe covers and the like.

TEST METHODS Handle-O-Meter: The softness of a non-woven fabric can be measured according to the "Handle-O-Meter" test. The test that was used here is the standard IND lero test. 90.0-75 (R 82) with two measurements: 1. the specimen size was 4 inches by 4 inches and 2. five specimens were tested rather than two. The test was carried out with a Handle-O-Meter model number 211-5 from Thwing-Albert Instrument Co., 10960 Dutton Road, Philadelphia, Pennsylvania 19154. The reading of the Handle-O-Meter is in units of grams.

Tension: The tensile strength of a fabric can be measured according to the ASTM D-1682-64 test. This test measures the resistance in pounds and the elongation in percent of a fabric.

Melt Flow Rate: The melt flow rate (MFR) is a measure of the viscosity of some polymers.

The melt flow rate is expressed as the weight of material flowing from a capillary vessel of known dimensions under a specified load or a cutoff rate for a given period was measured in grams / 10 minutes at 230oc according to, for example, the ASTM D-1238 -90b test, condition L.

DETAILED DESCRIPTION The important properties of the polyolefin used in spinning processes are known to those skilled in the art. The melt flow rate and viscosity are interrelated and are very important to characterize a polymer. The melt flow rate is related to the viscosity of the polymer with a higher number indicating a lower viscosity. The test for the melt flow rate is defined above.

The spinning process generally employs a hopper which supplies a polymer to a heated extruder. The extruder supplies the melted polymer to a spinning organ where the polymer is fiberized as it passes through the five openings arranged in one or more rows in the spinning organ, forming a curtain of filaments. The filaments are usually cooled with air at a low pressure, pulled, usually pneumatically and deposited on a mobile foraminous mat, band or "forming wire" to form the non-woven fabric. The polymers useful in the spinning process generally have a melting temperature of between about 400OF to about 6IO0F (220to 320oC).

The fibers produced in the co-bonding process are usually in the range of from about 15 to about 50 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 decreasing the processing temperature results in longer diameter fibers. Changes in the temperature of the cooling fluid and the pneumatic pulling pressure can affect the diameter of the fiber. In this invention, the particular polymer used allows the fibers to be produced to a smaller diameter than usual for a spun bond.

The fabric of this invention is a multilayer laminate incorporating the superior melt flow polymer fiber fabric and can be formed by a number of different techniques including but not limited to the use of adhesive, needle punching, ultrasonic bonding, thermal calendering and any other method known in the art. Such a multilayer laminate may be an embodiment wherein some of the layers are spunbonded and some are meltblown such as a spunbonded / meltblown / spunbond (SMS) laminate as discussed in the patent of United States of America No. 4,041,203 issued to Brock et al., and in United States of America No. 5,169,706 issued to Collier et al. or as a spunbonded / spunbonded laminate. An SMS laminate can be made by depositing the sequence on a mobile conveyor belt or a forming wire first a layer of spunbonded cloth, then a layer of meltblown cloth, and finally another spunbonded layer and then joining the laminated in a manner described above. Alternatively, the three layers of fabric can be made individually, collected in rolls and combined in a separate joining step.

Various patterns for calendering rollers have been developed. One example is the Hansen Pennings pattern expanded with around a 15% area of union with about 100 unions / square inch as taught in U.S. Patent No. 3,855,046 issued to Hansen and Pennings. Another common pattern is a diamond pattern with slightly off-center and repetitive diamonds.

The fabric of this invention can also be laminated with films, glass fibers, short fibers, paper and other commonly used materials known to those skilled in the art.

The areas in which the fabric of this invention can find utility are garments, medical products, personal care products, fabrics for the exterior. More particularly, fabrics produced according to this invention are useful in heavier basis weight applications such as protective covers. Protective covers usually have base weights ranging from about 2 ounces per square yard (68 grams per square meter) to about 8 ounces per square yard (278 grams per square meter), therefore, a fabric produced according to this invention preferably will have basis weights ranging from about 0.2 ounces per square yard (7 grams per square meter) to about 3 ounces per square yard (102 grams per square meter).

A polyolefin polymer useful in this invention should have a higher melt flow rate and a lower viscosity. The desired melt flow rate for the polyolefin to be used in this invention is at least 50 gms / 10 minutes according to ASTM D-1238-90b, condition L, and preferably in the range of from about 50 gms (10 minutes to about 150 gms / 10 minutes according to ASTM D-1238-90b, condition L. The viscosity of the polymer was measured at 180oC and must be at least 2.5 x 103 days. / cm2 and preferably in the range of 2.5 x 103 days / second to about 6.5 x 103 seconds / cm2 The higher melt flow rate and lower viscosity allow the fibers to be pulled more highly than the which could be otherwise, producing very fine spunbonded fibers The fibers produced with the higher melt flow polyolefin employed herein are in the range of about 11 about 20 microns in diameter.

An advantage of fine spunbonded fibers can be seen in the new version where energy is applied to the fabric through various means to induce the fibers to melt slightly together. It is believed by the inventors that smaller fibers made of lower viscosity polymers allow more polymer to flow to the bonding points during bonding, thus ensuring a stronger bond, and yet the fabric retains the advantage of softness which is given by the smallest fibers.

The production of a higher melt flow rate polyolefin can be achieved when starting with a conventional lower melt flow polyolefin through the action of free radicals which degrade the melt flow polymer low to high. Such free radicals can be created and / or made more stable through the use of a prodegradant such as a peroxide, an organometallic compound or a transition metal oxide. Depending on the prodegradante chosen, the stabilizers can be useful.

An example of a way to make a higher melt flow polyolefin from a conventional melt flow polyolefin is to incorporate a peroxide into the polymer.

The addition of the peroxide of a polymer for meltblown applications is taught in U.S. Patent No. 5,213,881 issued to Timmons et al. In Timmons, up to about 3000 ppm of peroxide are added to a polymer which has been polymerized with a Ziegler-Natta catalyst. The polymer is in the form of reactor granules and has a molecular weight distribution of 4.0 to 4.5 Mw / Mn and a melt flow rate of about 400 gms / 10 minutes according to ASTM D-1238-90b. , condition L before modification. Such a polymer is modified by the peroxide to have a molecular weight distribution in the range of about 2.2 to 3.5 Mw / Mn and a melt flow rate of about 800 to 5000 gms / 10 minutes according to the ASTM D standard. 1238 -90b, condition L. The addition of the peroxide to the polymer pellets is also mentioned in United States Patent No. 4,451,589 issued to Morman et al.

The addition of peroxide to a polymer for spin bonding applications is made by adding up to 1000 ppm of peroxide to a commercially available low melt flow rate polyolefin polymer and mixing thoroughly. The resulting modified polymer will have a melt flow rate of approximately two to three times that of the starting polymer depending on the rate of peroxide addition and the mixing time.

Another way to make a higher melt flow polyolefin from a conventional low melt flow polyolefin is by adding an organo-metallic compound to the polyolefin. The organometallic compound has the effect of increasing the stability of the free radicals within the polymer which allows them to remain active for a longer period of time and therefore to degrade the polymer from the melt flow low to higher. Typically, the melt flow can be changed from about 35 to the range of about 70 to 85 using this method.

The suitable organo-metallic compound is sodium bis (para-5-butylphenyl) phosphate. An example of a suitable commercially available organo-metallic compound is that sold by Witco Chemical Company of New Jersey, under the Mark 2180 mark. When an organometallic compound is used it can be used in an amount of from about 0.1 percent by weight. weight at around 5 percent by weight. The organometallic compounds have the added benefit of giving the fabric an improved resistance to ultraviolet light, important in outdoor applications, as well as giving color to the fabric, since most of the organometallic compounds also They are pigments.

The organometallic compound can be added to the polyolefin to be spun before entering the extruder. It is important that the organometallic compound and the polyolefin are mixed as thoroughly as possible in order to provide as uniform a mixture as possible to the spinning organ. The uniformity in the composition fed to the spinning organ helps to ensure uniform fiber production and to reduce broken fibers and iridescence. A suitable method of blending the polyolefin and the organometallic compound is to add the organometallic compound, generally a powder, to the polyolefin, generally in pellet form, in a large mixing vessel prior to the addition to the hopper as previously described. Alternatively, the organometallic compound can be added to the polyolefin in the hopper.

Yet another method is to add the organometallic compound in a controlled manner at a number of points along the length of the extruder as it is melted and the polyolefin moved forward towards the spinning organ. This method would allow greater control of the process since it also provides the smallest margin of error in the rate of addition, since changes in the addition rate will more immediately affect the uniformity of the fibers produced.

Yet another way to make a higher melt flow polyolefin from a conventional low melt flow polyolefin is to add a metal acid with transition to the polymer during processing. Suitable transition metal oxides, such as, for example, ferric oxides. An example of a suitable commercially available transition metal oxide is that sold by Engelhar Corporation under the trademark Fe-0301-P. When a transition metal oxide is used it can be used in an amount of from about 0.1 weight percent to about 5 weight percent. The transition metal oxides can be added to the polyolefin in the manner described above. Transition metal oxides have the added benefit of giving the fabric improved resistance to ultraviolet light, which is important in outdoor applications, as well as giving a color to the fabrics, since most of the oxides of transition metal are also pigments.

It is also believed that a combination of a number of the above-mentioned techniques will be successful in producing a polyolefin of the desired melt flow rate.

The polyolefin useful in that invention may be polyethylene, polypropylene, polybutylene or copolymer mixtures thereof. Polypropylene is preferred.

In addition to the above-mentioned methods, higher melt flow polypropylenes are commercially available from Shell Chemical Company, of Houston, Texas co WRD5-1131, WRD5-1155 to 1157, WRD5-1160 to 1162, from Exxon Chemical Company, Baytown, Texas as PLTD-739, PLTD-766, PLTD-782, PLTD-926, PLTD-927 and others, and Himont Corporation of Wilmington, Delaware as X11029-20-1 and X1129-20-2. These materials have melt flow rates above 60 according to ASTM D-1238-90b, condition L. Commercially available polymers may or may not have been chemically treated and / or modified in order to raise their flow rates. melted.

The polymers employed in the practice of this invention provide not only a higher melt flow rate, but are also believed to be responsible for the superior strength in the resulting fabric after bonding. Therefore, it has surprisingly been found that the fabric of this invention has a tensile strength of less than 10% more than the fabric made of the same polymer without modification at a higher melt flow rate.

Although the fabric made of the above melt flow rate polymer fibers described above can be used in a laminate with only a low melt flow rate polymer fabric, it is preferred that the fabric be laminated other materials as well. Such materials include meltblown fabrics, films and other fabrics bonded together.

The films, and the meltblown fabrics bonded with spinning can be made of any material known in the art to be suitable for such applications. This includes polyamides, polyesters, polyetheresters, polyurethanes, polyolefins and copolymers, terpolymers and mixtures thereof. The fabrics can be made of fibers constructed in a bicomponent configuration as defined above. Thermoplastic elastomeric polymers can be used to form such films and fabrics as well. The elastomeric polymers are preferably selected from those made from styrenic block copolymers, polyurethanes, polyamides, copolyesters, ethylene vinyl acetates (EVA) and the like.

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

U.S. Patent No. 4,063,220 issued to Wisneski et al. Discloses a tel including microfibers comprising at least about 10 percent by weight of an ABA block copolymer where "A" and "A" are each a thermoplastic end block and which comprises a styrenic half and wherein "B" is a medium elastomeric poly (ethylene-butylene) block, and from more than percent by weight to about 90 percent by weight d a polyolefin which when mixed with an ABA 'block copolymer and subjected to an effective combination of elevated temperature and high pressure conditions, is adapted to be extruded in a form blended with the ABA' block copolymer. The polyolefins useful in Wisneski and other may be polyethylene, polypropylene, polybutene, ethylene copolymer, ethylene copolymers, propylene copolymers, butene copolymers and mixtures thereof.

Commercial examples of such elastomeric copolymers are, for example, those known with KRATON® materials which are available from Shell Chemica Company, of Houston, Texas. KRATON block copolymers are available in several different formulas, a number of which are identified in U.S. Patent No. 4,663,220 incorporated herein by reference. Particularly suitable elastomeric polymers are elastomeric poly (styrene / butylene-ethylene / styrene) block copolymers available from Shell Chemical Company of Houston, Texas under the trade designations KRATON® G-1657 and KRATON G-2740.

In the laminate of this invention it has been found that an intermediate layer, such as a meltblown layer, appreciably changes the strength and softness properties of the final laminate when compared to those without the intermediate layer.

The fall is a measure of the softness of a tel and refers to what the fabric is also shaped to an object on which it is placed. A soft fabric will fall better in conformation with the outline of the object on which it is placed than it will be by a more rigid fabric. The fall was measured by a Handle-O-Meter test which was previously defined.

The strength of a fabric was measured by the stress test which was previously defined.

Fabrics made according to this invention have been found to have a comparable drop and superior tensile properties in terms of fabrics made of conventional polypropylene.

The following control and examples show the characteristics of the fibers of the polymers that meet the requirements of this invention against those that do not. All samples were linked with the expanded Hansen-Pennings pattern described above. The results are shown in Table 1.

CONTROL A cloth was produced which was a laminate joined by spinning / spunbonded (SS). The base weight of the layers was 1 ounce per square yard (34 grams per square meter) and 1 ounce per square yard (34 grams per square meter). Both layers were made from the same low melt rate polypropylene: PF301 from Himont Chemical Co. The fibers were spun at a temperature of about 390-440oF (199-221oc). The size of the orifice of the spinning organ was 0.6 mm with a production between 0.5 and 0.7 grams / hole / minute) (ghm) to produce the fiber of 21 microns in diameter.

EXAMPLE 1 A cloth was produced which was a laminate joined by spinning / spunbonded (SS). One layer was produced from a higher melt flow rate polypropylene and the other from a conventional low melt flow rate polypropylene. The basis weight of the layers was 1 ounce per square yard for the upper melt flow rate layer and 1 ounce per square yard for the low melt flow rate layer. The higher melt flow rate polypropylene was produced by the addition of 1000 to 1500 ppm of Himont polypropylene peroxide PF-301. The melt flow rate of the polymer after the peroxide treatment was around 110 according to ASTM D-1238-90b, condition L. The fibers of the upper melt flow rate were spun at a temperature of about 390-430 ° F (199-221 ° C). The size of the orifice of the spinning organ was 0.6 mm with a production between 0.5 and 0.7 grams / hole / minute (ghm) to produce a fiber of 15 microns in diameter.

The low melt flow rate polypropylene used was PF-301 from Himont. The fabric was produced by spinning fibers at control conditions.

The laminate was produced by first depositing the low melt flow layer on a forming wire and then depositing the upper melt flow polymer layer directly on the melt flow polymer layer under the tibia.

EXAMPLE 2 A cloth was produced which was a laminate joined by spinning / spunbonded (SS). One of the layers was produced from a higher melt flow rate polypropylene and the other from a conventional low melt flow rate polypropylene. The basis weight of the layers was the same as in Example 1. The higher melt flow rate polypropylene was produced by the addition of 0.65 weight percent of an organometallic compound to the polypropylene PF-301 from Himont. The melt flow rate of the polymer after the organometallic treatment was 80, according to the standard AST D-1238-90b, condition L. The organometallic compound was a talo-Fe203-cinanine which is available as blue-gray pigment from Standridge Chemical Company of Social Circle, Georgia, as SCC6142. After the addition, the polypropylene / organometallic mixture was thoroughly combined.

The higher melt rate fibers were spun at the same conditions as in Example 1 to produce fiber of 12 microns in diameter.

The lower melt flow rate polypropylene was PF-301 from Himont. The fabric was produced by spinning fibers to the same conditions as in Example 1 to produce fibers of 19.5 microns in diameter.

The laminate was produced by first depositing the lower melt flow layer on a forming wire and then depositing the upper melted flow polymer layer directly on the warm lower melt flow polymer layer.

EXAMPLE 3 A cloth was produced which was a laminate joined by spinning / spunbonded (SS). One layer was produced from a higher melt flow rate polypropylene and the other from a conventional low melt flow rate polypropylene. The basis weight of the layers was the same as in Example 1. The higher melt flow rate polypropylene was produced by the addition of 0.65 weight percent of an organometallic compound to the polypropylene PF-301 of Himont. The melt flow rate of the polymer after organ-metal treatment was 80, according to AST standard D-1238-90b, condition L. The organo-metallic compound used was designated Fe203 / Fe and was commercially available from Engelhar Corporation. After the addition, the polypropylene / organometallic mixture was thoroughly combined. The higher melt flow rate fibers were spun to the same conditions as in Example 1 to produce quincunde fiber diameter.

The lower melt flow rate polypropylene was a mixture of PF-301 from Himont and Escorene® 3445 from Exxon Chemical Company. The fabric was produced by spinning fibers to the same conditions as in Example 1 to produce the fiber of 19.5 microns in diameter.

The lamination was produced by first depositing the low melt flow layer on a forming wire and then depositing the upper melt flow polymer layer directly on the lower melt melt flow rate polymer layer.

TABLE 1 Fiber Size Normalized Lengthening Tension Energy Handle-O-Meter # Sample Id BW (mieras) Cd Md Cd Cd Md 0 Control 2 19-25 30 60 54.3 82.8 97.7 1 Example 1 2 19-25 34 67 74 56.4 94.2 2 Example 2 2 19-25 39 78.5 78.6 89.8 82.6 3 Example 3 2 19-25 38. 5 76 76 51.1 73 The results show that the laminates made of the polyolefin spun fibers having the designated characteristics can have a higher strength than those of the unmodified polymers. The fabrics bonded by strong polyolefin spinning have not been produced to what the inventors know, with a softness comparable to that of the fabrics attached by conventional polyolefin spinning in the past.

Claims (18)

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

1. A polyolefin fabric joined by a soft and strong woven yarn comprising: a first woven of spunbonded fibers produced from a polyolefin polymer having a melt flow rate of at least 50 grams / 10 minutes where said polyolefin polymer was initially produced with a reactor pellet through the use of the catalyst Ziegle Natta with a flow rate of melted below 50 grams / minutes and subsequently modified by a method selectable from the group consisting of the addition of from a positive quantity up to 1000 ppm of peroxide, the addition of from a positive quantity up to 5 percent by weight of sodium bis (para-t-butylphenyl) phosphate and the addition of from a positive quantity up to 5 percent by weight of a transition metal oxide, in order to increase the flow rate of melted p a factor of at least two, and; a second spunbonded fabric produced from polyolefin polymer having a melt flow rate of below 50 grams / 10 minutes; wherein said fabrics are joined together to form a laminate having a strength of at least 10% greater than that of the same laminate made when said first melt flow rate of tissue polymer does not exceed 50 grams / 10 minutes at 230 ° C.

2. The fabric bonded by non-woven yarn as claimed in clause 1, characterized in that it has a basis weight of between about 0.2 ounces per square yard and about 3 ounces per square yard. 3. The non-woven fabric as claimed in clause 1, characterized in that it comprises a third layer selected from the group consisting of melt blown fabrics and films and placed between said first and second fabrics. 4. The non-woven fabric as claimed in clause 3, characterized in that said third layer is a meltblown fabric which is made of a polymer selected from the group consisting of polyurethanes, polyether esters, polyamides, polyolefins, polyolefin copolymers and mixtures thereof. 5. The non-woven fabric as claimed in clause 4, characterized in that said third layer is a meltblown fabric which is made of a styrenic block copolymer. 6. The non-woven fabric as claimed in clause 3, characterized in that said third layer is a film which is made of a film-forming polymer selected from the group consisting of polyurethanes, polyetheresters, polyamides, polyolefin polyolefin copolymers and mixtures thereof. 7. The non-woven fabric as claimed in clause 6, characterized in that said film-forming polymer is a styrenic block copolymer. 8. The non-woven fabric as claimed in clause 3, characterized in that said layers are joined together to form a laminate by a method selected from the group consisting of thermal bonding, ultrasonic bonding, bonding with needle piercing and adhesive bonding . 9. The non-woven fabric as claimed in clause 3, characterized in that it is present in a product selected from the group consisting of medical products, garments, personal care products and outdoor fabrics. 10. A diaper comprising the fabric as claimed in clause 3. 11. A product for feminine hygiene that comprises the fabric as claimed in clause 3. 12. A surgical suit comprising the fabric ta and as claimed in clause 3. 13. A mask for the face that includes the tel as claimed in clause 3. 14. A cleaner comprising the fabric as such is claimed in clause 3. 15. A polyolefin fabric bonded by strong and soft weaving yarn comprising: a first spin-bonded fiber fabric produced from polyolefin polymer having a melt flow rate of at least 50 grams / 10 minutes and a viscosity of at least 2500 dies. second / cm2 and; a second woven of spunbonded fibers produced from polyolefin polymer having a melt flow rate of below 50 grams / 10 minutes; wherein said fabrics are joined together to form a laminate having a strength of at least 10% or greater than that of the same laminate made when said first melt flow rate of woven polymer does not exceed 50 grams / 10 minutes at 230 ° C. 16. The non-woven fabric as claimed in clause 15, characterized in that it comprises a third layer selected from the group consisting of melt blown fabrics and films and placed between said first and second fabrics. 17. The non-woven fabric as claimed in clause 16, characterized in that said third layer is a meltblown fabric which is made of a polymer selected from the group consisting of polyurethanes, polyetheresters, polyamides, polyolefins, polyolefin copolymers and mixtures thereof. 18. The non-woven fabric as claimed in clause 16, characterized in that said third layer is a film which was made of a film-forming polymer selected from the group consisting of polyurethanes, polyetheresters, polyamides, polyolefins, polyolefin copolymers and mixtures thereof.

3. 6 E S U M E N A spunbonded nonwoven fabric is provided which has strength characteristics superior to those of conventional fabrics and yet is still comparably smooth. The fabric is a laminate having a fabric made of a higher melt flow rate polyolefin polymer of a lower melt flow rate polymer. The spunbond laminate of this invention may have therein a layer of co-melt blowing nonwoven fabric or film. The laminate produced according to this invention has a strength which is at least 10% greater than that of a comparable fabric made with the higher melt flow rate polymer fabric. The non-woven fabric of this invention can be used in products such as, for example, garments, personal care products, medical products, protective coverings and outdoor fabrics.