MXPA99001610A - Single extruder multiportion fiber - Google Patents

Abstract

A method of producing a fiber is provided where a liquefied polymer is divided into at least two streams. The streams are directed separately to a point of recombination, and extruded through, for example, a spinneret, and fiberized to form a single fiber having portions of each stream. The divided polymer streams are treated substantially identically from the point of division to the point of recombination.

Description

FIBER OF MULTIPLE PARTS OF UNIQUE EXTRUDER BACKGROUND OF THE INVENTION This invention relates generally to a non-woven fiber and to fabrics or fabrics which are formed of such fibers, and laminates using such a fabric as a component. The fibers are made of a thermoplastic resin.

For several years, thermoplastic resins have been extruded to form fibers, fabrics and fabrics. The most common thermoplastics for this application are polyolefins, particularly polypropylene. Other materials such as polyesters, polyetheres esters, polyamides, and polyurethanes are also used to form non-woven spunbonded fabrics.

Non-woven fabrics or fabrics are useful for a wide variety of applications such as diapers, hygiene products for women, towels, recreational or protective fabrics and geotextiles and filter media. The non-woven fabrics used in these applications can be simply spun-bonded fabrics but are often in the form of non-woven laminates such as spin-linked / spin-bonded laminates (SS) or melt-bonded spin / bonded laminates. by spinning (SMS).

Spunbond fibers are commonly monocomponent fibers but may also be multi-component. The multi-component fibers may be conjugated or biconstituent fibers, or a combination of the two. The term "conjugated fibers" has traditionally referred to fibers formed from more than one polymer of more than one extruder wherein the polymer portions remain essentially unmixed and continuous along the length of the fiber. The term "biconstituent fibers". has referred, traditionally. to fibers formed from a mixture or combination of polymers wherein each polymer is not continuous along the length of the fiber.

At. rte are known, conjugate and biconstituent fibers. Some good examples of these can be found in the patent of the United States of America? 5,382,400 granted to Pike and others, commonly assigned. A good example of biconstituent fibers can be found in U.S. Patent No. 5,534,335 issued to Everhart et al.

Many of the above efforts to produce conjugated or biconstituent fibers have been focused on combining polymers which are not normally especially compatible, such as polyolefins and polyamides, or different polyolefins such as polypropylene and polyethylene. Little attention has been directed to producing a conjugated fiber, for example, from the same polymer and those who have researched this area have used the traditional conjugate production mechanism of using an extruder for each part of the fiber. U.S. Patent No. 5,318,552 issued to Shiba, for example, provides a conjugate fiber wherein both parts are made of the same type of polymer, polyester, however the chosen polyesters must have a melting temperature of at least 50oC. U.S. Patent No. 4,551,378 issued to Carey, Jr., like that of Shiba, teaches conjugated fibers having parts which can be formed of the same class of polymers but which have a difference in the melting point. The patent of the-. United States of. North America No. 5,451 ^ 462 awarded, "to Taniguchi" and • others teaches one. Fiber, .conjugate made only of polypropylene but uses polypropylenes having different proportions of isotactic pentada. U.S. Patent Application No. 08 / 375,196, commonly assigned, teaches the production of conjugated fibers from separate extruders but using the same polymer, without modification in any way. U.S. Patent No. 3,780,149 issued to Keuchel et al. Teaches the production of a fiber having multiple portions of only one extruder and using the same starting polymer. Keuchel and others, however, divide the polymer and subject the divided currents to different cutting and thermal environments before the fiberization in order to improve the curling potential of the fiber.

Apparently it has appeared to be unsuccessful to produce a multi-part fiber using the same polymer from the same extruder, perhaps due to the cost involved or the skepticism about the quality of the fiber, and it is the object of this invention to produce such fiber. It is a further object of this invention to produce a non-woven tel-a made of such fiber--, SYNTHESIS OF THE INVENTION The objects of this invention are achieved by a method to produce a fiber-in-a-one. Olimer is liquefied, divided into at least two parts, recombined, and extruded to form a single fiber. The streams are directed separately to the recombination point and are then extruded through, for example, a spinning organ, and are fiberized to form a single fiber having portions of each stream. The divided polymer streams are treated essentially identically from the point of cleavage to the point of recombination. The fiber thus produced can be continuous or discontinued and can be processed into a short fiber by cutting. The fiber can be a microfiber or much larger. Any polymer which can be liquefied and successfully extruded can be used in the practice of this invention.

DEFINITIONS As used herein the term "non-woven fabric or fabric" means a fabric having a structure of individual threads or fibers which are interlocked, but not in an identifiable manner as in a woven fabric. Non-woven fabrics or fabrics have been formed from many processes such as, for example, melt blowing processes, spinning processes and the processes of bonded carded fabric. The 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 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, The microfibers can have an average diameter of from about 2 microns to about 40 microns. Another frequently used expression of fiber diameter is the denier which is defined as grams per 9000 meters of a fiber and can be calculated as the fiber diameter in square microns, multiplied by the density in grams / cc, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a polypropylene fiber given as 15 microns can be converted to denier by squaring, multiplying the result by .89 g / cc and multiplying by .00707. Therefore, a polypropylene fiber of 15 microns has a denier of about 1.42 (152 x 0.89 x .00707 = 1.415). Outside the United States of America, the unit of measurement is more "commonly" and "tex ^ f" 'hl cii l It is defined as grams per kilometer of fiber. The tex can be calculated as the denier / 9.

As used herein, the term "spunbond fibers" refers to small diameter fibers formed by extruding the thermoplastic material-sold as filaments of a plurality of usually circular and fine capillaries of a spinner organ with the diameter of the extruded filaments then being rapidly reduced as by, for example, in U.S. Patent No. 4,340,563 issued to Appel et al., and in U.S. Patent No. 3,692,618 granted to Dorschner et al., in United States of America Patent No. 3,802,817 issued to Matsuki et al., in United States of America No. 3 patents, 338,992 and 3,341,394 issued to Kinney, United States Patent No. 3,502,763 issued to Hartman, and United States Patent No. 3,542,615 issued to Dobo and others. Spunbonded fibers are not generally sticky when they are deposited on a collecting surface. Spunbond fibers are generally continuous and have average diameters (of a sample of at least 10) greater than 7 microns, more particularly, between about 10 and 20 microns.

As used herein, the term "meltblown fibers" means fibers formed by extruding a melted thermoplastic material through a plurality of capillaries of matrix, usually circular and thin like melted threads or filaments into gas streams. (for example -of air), usually hot, ...- of, - at the speed and converging which attenuate -the filaments of thermoplastic material- melted to reduce its diameter which can be a microfiber diameter. 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 a process is described, for example, in United States Patent No. 3,849,241 issued to Butin et al. The fibers formed by meltblowing are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in average diameter, and are generally sticky when deposited on the collecting surface.

As used herein, "multilayer laminate" means a laminate wherein some of the layers are spunbonded and some are formed by meltblowing such as a meltblown / spunbonded (SMS) spin-bonded laminate. and others as described in U.S. Patent No. 4,041,203 to Brock et al., U.S. Patent No. 5,169,706 to Collier et al., U.S. Pat. No.5, 145, 727 granted to Potts and others, United States Patent No. 5,178,931 to Perkins, and others, and to the United States of America No. - 5,188,885 granted; to Timmons-: and ~ others -.-- Tai-laminate can be made by sequentially depositing on a mobile forming band first a layer of spunbonded cloth, then a layer of melt-blown fabric and finally another bonded layer by spinning and then attached to the laminate in a manner as described below. Alternatively, the fabric layers can be made individually, collected in rolls, and combined in a separate bonding step. Such fabrics usually have a basis weight of from about 6 to 400 grams per square meter, or more particularly from about 0.75 to about 3 ounces per square yard. The multi-layer laminates may also have several numbers of layers formed by meltblown or multiple spin-bonded layers in many different configurations and may include other materials such as films (F) or coform materials, for example, SMMS, SM, SFS, etc.

As used herein, the term "polymer" generally includes but is not limited to homopolymers, copolymers, such as, for example, block copolymers? grafted, random and alternating, terpolymers, etc. and the mixtures and modifications thereof. In addition, unless specifically limited otherwise, the term "polymer" will include all possible geometric configurations of the molecule. These configurations include, but are not limited to * syntactic, syntactic, and random symmetries. - ... --- As used herein the term "monocomponent" fiber refers to a fiber formed from one or more extruders using only one polymer. This is not intended to exclude fibers formed from a polymer to which small amounts of additives have been added for coloring, antistatic properties, lubrication, hydrophilicity, etc. These additives, for example, titanium dioxide for coloration, are generally present in an amount of less than 5 percent by weight and more typically of about 2 percent by weight.

As used herein the term "conjugated fibers" refers to fibers which have been formed from at least two polymers extruded from separate extruders but spun together to form a fiber. Conjugated fibers are also sometimes referred to as bicomponent or multi-component fibers. The polymers are usually different from one another even though the conjugated fibers can be made from monocomponent fibers. The polymers are arranged in distinct zones placed essentially constantly across the cross section of the conjugated fibers and continuously extending along the length of the conjugated fibers. The configuration of such conjugated fiber can beFor example, a pod / core arrangement in which one polymer is surrounded by another or can be a side arrangement, on the side, a cake arrangement or an arrangement of islands, and the sea. -Conjugated fibers are taught in the patent of the United States of North America No. 5,108,820 issued to Kaneko et al., In United States Patent No. 4,795,668 issued to Krueger et al., And in United States Patent No. 5,336,552 issued to Strack et al. Conjugated fibers are also taught in the patent of the United States of America? O. 5,382,400 issued to Pike et al., And can be used to produce a ripple in the fibers by employing the different rates of expansion and concentration of two polymers (or more). The crimped fibers can also be produced by mechanical means and through the process of the German patent DT 25 13 251 Al. For the bicomponent fibers, the polymers can be present in the proportions of 75/25, 50/50, 25/75 or any other desired proportions. The fibers may also have shapes such as those described in US Patents No. 5,277,976 States granted to Hogle et al in Patent United States No. 5,466,410 issued to Hills and 5,069,970 and 5,057,368 issued to Largman and others, which describes fibers with unconventional shapes. - - ~ >; -..-. i.; ----- - = - ..--- "•. ---.-... £ .. - __-: _- x_ 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 ^ "mixtures" - "is defined abjo!" The "fibras" - "biconstituent" no, have many different polymer components arranged in different zones placed relatively constant across the sectional area. The fiber cross section and the various polymers are usually not continuous along the entire length of the fiber, instead of usually forming fibrils or protofibrils which start and end at random.The biconstituent fibers are sometimes also mentioned as Multi-constituent fibers Fibers of this general type are discussed in, for example, US Pat. Nos. 5,108,827 and 5,294,482 issued to Gessner. The biconstituent and component fibers are also discussed in the text "Mixtures and Polymer Compounds "by John A. Manson and Leslie H. Sperling, copyright 1976 by Plenum Press, a division of the 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 immutable but have been compatibilized.

As used herein the term "single extruder multi-fiber fibers" means fibers made from only one extruder and one polymer but having portions as a conjugated fiber. The configuration of such a fiber can be, for example, a pod / core arrangement where a part is surrounded by another - or it can be a side-by-side arrangement, - a cake arrangement, or an arrangement of "islands in the sea".

TEST METHODS Melt Flow Rate: The melt flow rate (MFR) is a measure of the viscosity of a polymer. The melt flow rate is expressed as the weight of material which flows from a capillary with known dimensions at a specified cut-off rate or load for a measured period of time and is measured in grams / 10 minutes at a temperature and load fixed according to, for example, the ASTM 1238-90b test.

DETAILED DESCRIPTION The process of this invention can be made to produce fibers, including short fibers and continuous fibers which can be further processed into nonwoven, woven or woven fabrics. The common processes for-- the, production. from . Man-made fibers include meltblowing processes, spinning bonding process, spinning solution, various carpet yarn manufacturing processes and others known to those with skill in the art.

. A very familiar process is the process of union with-spinning. The spinning process generally uses a hopper which supplies the polymer to a heated extruder which melts the polymer. The extruder supplies the liquefied polymer to a spinning organ where the polymer is fiberized as it passes through the fine orifices or 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 or collected on a foraminous mat, band or "forming wire" to constitute the non-woven fabric. The polymers useful in the spinning process generally have a process melting temperature of between around The fibers produced in the spinning process are usually in the range of from about 10 to about 50 microns in average 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 larger diameter fibers. Changes in the cooling fluid temperature and the pneumatic pulling pressure can also affect the diameter of the fiber. The fibers produced through the spinning bond process usually have average diameters in the range of about 7 to about 35 microns., more particularly from-about 10 to about 25 microns while those produced by other methods can be larger. Carpet threads, for example, are much longer than 50 microns in diameter in the range of 100 to 200 denier and larger.

The fiber of this invention can be formed into a multilayer laminate which can be formed through a number of different techniques including but not limited to adhesive, needle perforation, stitch bonding, ultrasonic bonding, thermal calendering and any other method known in the art. Such a multilayer laminate may be a mode wherein some of the layers are produced through the spinning method and some are produced through the meltblowing method such as the melted / bonded spin / melt laminate. by spinning (SMS) as described in United States Patent No. 4,041,203 issued to Brock et al. and in United States Patent No. 5,169,706 issued to Collier et al. or as a spin-linked laminate. / joined by spinning. An SMS laminate can be made by depositing sequences on a moving conveyor belt or a forming wire first a layer of spin-knitted fabric, then a layer of melted blown fabric and at the last another layer spun-bonded and then joining the laminate into a manner described above. Alternatively,:, the "three new layers of fabric can be made individually, collected in rolls, and combined in a separate bonding step.

The polymers used to produce the fibers of this invention can be any of which can be liquefied and extruded such as polyamides, polyurethane, polyvinyl chloride, polytetrafluoroethylene, polystyrene, polyethylene terephthalate, polycarbonates, methyl-l-pentene, rayon, acetates, polyesters and polyolefins, particularly polypropylene and polyethylene. The elastomeric thermoplastic polymers can be processed in the manner of the invention as well. The polymer can be made liquid by melting or by a chemical reaction, or by other means known in the art.

Many polyolefins are available for fiber production, for example, polyethylenes such as linear low density polyethylene from Dow Chemical ASPUN®6811A, high density polyethylene 2553 LLDPE and 25355 and 12350 are suitable polymers. The polyethylenes have melt flow rates, respectively, of about -26, 40; 25 ~? 12. Fiber-forming polypropylenes include Escorene® PD 3445 polypropylene from Exxon Chemical Company, numerous polypropylenes from Shell Chemical Company and Montell Chemical Co PF-304. Many other polyolefins are available commercially - ~ ?: - - ... - _. = =. - - -- - , -1 _•-- _ -- .

The elastomeric thermoplastic polymers useful in the practice of this invention may be those of block copolymers such as polyurethanes, copolieter esters, block copolymers of polyamide polyether, ethylene vinyl acetates (EVA), block copolymers having the general formula AB-A'o AB as copoly (styrene / ethylene-butylene), styrene-poly (ethylene-propylene) -styrene, styrene-poly (ethylene-butylene) -styrene, (polystyrene / poly (ethylene-butylene) / polystyrene, oli (styrene / ethylene-butylene / styrene) and the like.

Useful elastomeric 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 styrene group such as poly (vinyl arene) and wherein B is a middle block of elastomeric polymer such as a conjugated diene or a lower alkene polymer. Block copolymers of type A-B-A 'can have 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 regard, radial block copolymers can be designated (A-B) m-X, where X is a polyfunctional atom or a molecule and in which (A-B) m-radiates from X into a form-which A is-an extremeblock-,, In the block copolymer. radial, X must be im: atom-o = olifunctional-organic or inorganic molecular and m is an integer having the same value as the functional group originally present in X. This is usually at least 3, and this is frequently 4 or 5, but it is not limited to this. Therefore, in the present invention the term "block copolymer" and particularly block copolymer "ABA '" and "AB", is intended to encompass all block copolymers having such rubberized blocks and thermoplastic blocks as discussed above. which can be extruded (for example by blowing melted) and without limitation as to the number of blocks. The elastomeric non-woven fabric may be formed of, for example, block copolymers (polystyrene / poly (ethylene-butylene) / polystyrene) elastomeric. 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 Nos. 4,663,220, 4,323,534, 4,834,738, 5,093,422 and 5,304, 599, incorporated herein by reference.

Polymers composed of an elastomeric tetrablock A-B-A-B copolymer can also be used in the practice of this invention :. Such polymers are discussed in U.S. Patent No. 5,332,613 issued to Taylor et al. In such polymers, A is a block of thermoplastic polymer and B is a unit of isoprene monomer hydrogenated to a unit of poly (ethylene-propylene) monomer essentially. An example of such a tetrablock copolymer is an elastomeric block copolymer of styrene-poly (ethylene-propylene) -styrene-poly (ethylene-propylene) or an elastomeric block copolymer SEPSEP available from Shell Chemical Company of Houston, Texas under the designation of trade KRATON® G-1657.

Other exemplary elastomeric materials which may be used include polyurethane elastomeric materials such as, for example, those available under the trademark ESTAÑE® from B.F. Goodrich & Co. or MORTHANE® from Morton Thiokol Corp., elastomeric polyester materials such as, for example, those available under the trade designation HYTREL® from E.l. duPont De Nemours & Company, and those known as ARNITEL®, formerly available from Akzo Plastics of Amhem, The Netherlands and now available from DSM of Sittard, The Netherlands.

Another suitable material is a polyester block amide copolymer having the formula: O O HO- E - C-PA - C --- 0 - PE - 0-] n - H Where n is a positive integer, PA represents a polyamide polymer segment and PE represents a polyether polymer segment. In particular, the polyether block amide copolymer has a melting point of from about 150 ° C to about 170 ° C, as measured in accordance with ASTM D-789; a melt index of from about 6 grams per 10 minutes to about 25 grams per 10 minutes, as measured in accordance with ASTM D-1238, condition Q (235 C / lKg load); a flexural modulus of flexure from about 20 Mpa to about 200 Mpa, as measured in accordance with ASTM D-790; a tensile strength at breaking from about 29 Mpa to about 33 Mpa as measured in accordance with ASTM D-638 and an ultimate elongation at break from about 500 percent to about 700 percent as it is measured by the ASTM D-638 standard. A particular interpretation of the amide copolymer of the polyether block has a melting point of about 152 ° C as measured in accordance with ASTM D-789; a melt index of about 7 grams per 10 minutes, as measured in accordance with ASTM D-1238, condition Q (235 C / lKg load); a modulus of elasticity in flexion of about 29.50 MPa, as measured in accordance with ASTM D-790; a tensile strength at breaking of about 29 MPa, one-measure of agreement in ASTM.D-639; and a -broad extension to about 650 percent as measured in accordance with ASTM D-638. Such materials are available in various classes and under the trade designation PEBAX® from Atochem Inc. Polyers Division (RILSAN®), of Glen Rock, New Jersey. Examples of the use of such polymers can be found in U.S. Patent Nos. 4,724,184, 4,820,572 and 4,923,742, incorporated herein by reference, to Killian et al and assigned to the assignee of this invention.

The elastomeric polymers also include copolymers of ethylene and at least one vinyl monomer such as, for example, vinyl acetates, unsaturated aliphatic monocarboxylic acids, and esters of such monocarboxylic acids. The elastomeric copolymers and the formation of the non-woven elastomeric fabrics of those elastomeric copolymers as described in U.S. Patent No. 4,803,117.

The thermoplastic copolyester elastomers include the copolieter esters having the general formula: OR ü-0- (CH) -a-OH "- -: -v 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 including 2, 4 and 6," m "and" n "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 350oF to about 400oF (176o to 205oC) when measured in accordance with ASTM D-2117. Commercial examples of such copolyester materials are, for example, those known as ARNITEL® formerly available from Akzo Plastics of Amhem, The Netherlands and now available from DSM of Sittard, The Netherlands, or those known as HYTREL® which is available from E.l. duPont de Nemours of Wilmington, Delaware. The formation of an elastomeric non-woven fabric of polyester elastomeric materials as discussed in, for example, U.S. Patent No. 4,741,949 issued to Morman and U.S. Patent No. 4,707,398 issued to Boggs, incorporated here by reference.

The polyamides which can be used in the practice of this invention can be any known polyamide by those skilled in the art including copolymers and mixtures thereof. Examples of polyamides and their synthesis methods can be found in the book "Polymer Resins" by Don E. Floyd (Library of Congress Catalog number 66-20811 Reinhold Publishing NY, 1966). Useful polyamides in commercial form are particularly nylon-6, nylon 6,6, nylon-11 and nylon-12. These polyamides are available from a number of sources such as Nyltech North America of Manchester, NH, Emser Industries of Sumter, South Carolina (nylons Grilon® &Grilamid®) and Atochem Inc. Polymers Division of Glen Rock, New Jersey (nylos Rilsan®) among others.

Thermoplastic polymers also include a new class of polymers which is mentioned herein as metallocene polymers or as produced according to the metallocene process. The metallocene process generally uses a metallocene catalyst which is activated, for example, ionized by a co-catalyst.

The metallocene process, and particularly the catalysts and systems,. Support- = catalyst are the subject of numerous patents. The United States patent of North America No. 4,542,199 issued to Kaminsky et al. Describes a process wherein MAO is added to toluene, the metallocene catalyst of the general formula (cyclopentadienyl) 2MeRHal where- Me is a de-transition metal, Hai is a. Halogen and R is cyclopentadienyl or an alkyl radical Cl to C6 or a halogen is added the ethylene is then added to form the polyethylene. U.S. Patent No. 5,189,192 issued to LaPointe et al. And assigned to Dow Chemical discloses a process for preparing the addition polymerization catalysts through metal center oxidation. The United States patent of , North America No. 5,352,749 granted to Exxon Chemical Patents, Inc. describes a method for polymerizing monomers in fluidized beds. U.S. Patent No. 5,349,100 discloses chiral metallocene compounds and the preparation thereof by creating a chiral center by enantioselective hydride transfer.

The co-catalysts are materials such as methylaluminoxane (MAO) which is the most common, other compounds containing 1 qui 1 to 1 um i n s and boron as t r i s (pen t a f luor of eni lo) bor, lithium tetrak (pentafluorophenyl) boron, and dimethylanilinium tetrakis (pentafluorophenyl) boron. The research is continuing on other co-catalytic systems or the possibility of minimizing or even eliminating alkylaluminiums due to problems of product contamination and handling. The important point is that the metallocene catalyst can be activated or ionized to a catiponic form by reaction with the monomer (s). that are going to be polymerized - - - - -...-.....]. -., -.

Polymers produced using metallocene catalysts have the unique advantage of having a very narrow molecular weight range. Polydispersity numbers (Mw / Mn) below 4 and still as low as 2 are possible for metallocene-produced polymers. These polymers also have a narrow short chain branching distribution when compared to similarly produced Ziegler-Natta type polymers.

It is also possible to use a metallocene catalyst system to control the isotacticity of the very close polymer when the selective stereo metallocene catalysts are employed. In fact, the polymers have been produced having an isotacticity of in excess of 99 percent. It is also possible to produce a highly syndiotactic polypropylene using this system.

-The control of the isotacticity of a polymer-can also result in the production of a polymer which contains isotactic blocks and blocks of atactic material alternating over the length range of the polymer chain. This construction results in an elastic polymer by virtue of the atactic part, .. Such synthesis-of-polymer is discussed -, in the journal Science, - ^ vol. 267,. (13-January 1995) page 191 an article by K.B. Wagner Wagner, in the discussion of his work of Coates and Waymouth, explained that the catalyst oscillates between the stereochemical forms resulting in a polymer chain that has continuous stretches of isotactic sterocenters connected to current lengths of atactic centers. Isotactic dominance is reduced by producing elasticity. Geoffrey W. Coates and Robert M. Waymouth, in an article entitled "Oscillating Esterocontrol: A Strategy for the Synthesis of Thermoplastic Elastomeric Polypropylene" page 217 in the same issue, discusses their work in which they use metallocene bis (2-phenylidene) ) zirconium dichloride in the presence of methylaluminoxane (MAO), and by varying the pressure and temperature in the reactor, oscillating the polymer form between isotactic and atactic.

Commercial production of metallocene polymers is somewhat limited but growing. Such polymers are available from Exxon Chemical Company of Baytown, Texas under the trade name EXXPOL® for polymers based on polypropylene and EXACT® for polymers based on polyethylene. Dow Chemical Company of Midland, Michigan has polymers commercially available under the name ENGAGE®. These materials are believed to be produced using selective non-stereo metallocene catalysts. Exxon generally refers to its catalytic technology as "catalysts of" single site "__ as long as _Dow it is, -refie-r -, as its" constrained geometry catalysts "under the name of INSIGHT ® to distinguish them from traditional Ziegler-Natta catalysts which have multiple reaction sites. Other manufacturers such as Fina Oil, BASF, Amoco, Hoechst and Mobil are active in the area and it is believed that the availability of the polymers produced according to this technology will essentially grow over the next decade. In the practice of this invention, elastic polyolefins such as those of polypropylene and polyethylene are preferred, more especially elastic polypropylene.

In addition, a compatible adhesive resin can be added to the extrudable compositions described above to provide self-bonding adhesive materials. Any adhesive resin can be used which is compatible with the polymers and can withstand the high processing temperatures (for example extrusion). If the polymer is mixed with processing aids such as, for example, polyolefins or extension oils, the adhesive resin must also be compatible with those, processing aids. Generally, hydrogenated hydrocarbon resins are resins preferred adhesives due to their better temperature stability. The adhesives of the REGALREZ® and ARKON®P series are examples of hydrogenated hydrocarbon resins. Z0NATAC®5í) -lita is an example of a terpene hydrocarbon. REGALREZ® hydrocarbon resins are available from Hercules Incorporated. Resins from the ARKON®P series are available from Arakawa Chemical (USA) Incorporated. Adhesive resins as described in the patent of the United States of America No. 4, 787,699, incorporated herein by reference are suitable. Other adhesive resins can also be used which are compatible with the other components of the composition and can withstand the high processing temperatures.

It is also possible to have other materials mixed in smaller amounts with the polymers used to produce the fiber layer according to the invention as the fluorocarbon chemicals to improve the chemical repellency which can be, for example, any of those mentioned in U.S. Patent No. 5,178,931, fire retardants, photostability improving chemicals or ultraviolet radiation resistance, and pigments to give each layer the same or different colors. Fire retardants and pigments for melt blown and spin-jointed thermoplastic polymers are known in the art and are internal additives. A pigment, for example Ti02, if used, is generally present in an amount of less than 5 percent by weight of the layer while other materials may be present in a cumulative amount of less, 25% by weight. ., .. • -_- • -'-.? - -_---: - Ú? .... -V -. ":: .- The chemicals for improving resistance to ultraviolet radiation can be, for example, hindered amines and other commercially available compounds. The hindered amines are discussed in U.S. Patent No. 5,200,443 issued to Hudson and examples of such amines are Hostavin TMN 20 from American Hoechst Corporation of Somerville, New Jersey, Chimassorb®944 FL from Ciba-Geigy Corporation of Hawthorne, New York, Cyasorb UV-3668 from the American Cyanamid Company of Wayne, New Jersey, and Uvasil-299 from Enichem Americas, Ine. from New York.

The fabrics of this invention may also have topical treatments applied to these for more specialized functions. Such topical treatments and their methods of application are known in the art and include, for example, alcohol repellency treatments, anti-static treatments and the like, applied by spraying, embedding, etc. An example of such topical treatment is the application of the Zelec® antistatic (available from E.l. duPont, of Wilmington, Delaware). .,. -. " ,,.

The sheath / core fibers have been successfully produced using this process with Shell E5D47 polypropylene, a polymer melt flow rate of 38 measured at 230 ° C and 2060 grams, at around 2_per cent by weight, TiOz, product code 41438, - of Ampacet Corp.,; -6-60- White Plains Rd., Tarrytown, NY 10591-5130. The polymer was liquefied by melting at a temperature of about 228 ° C in a single extruder which pumped the product through a metering pump.The metering pump served to precisely control the flow and to reduce fluctuations. A metering pump may not be necessary in other installations or may be replaced with other measurement means known in the art.The polymer then enters a polymer pond from which it passes to a breaker plate, also called a distribution plate, which It divides the polymer stream into two parts and directs the parts to each capillary vessel of the individual spinning organ.The two parts were subjected to the same process conditions while they were separated.The polymer parts were recombined in the spinning organ and They fiberized to produce fibers having an average diameter of around 20 microns at a rate of about r of 0.8 grams / hole / minute. The divider plate was located on one side of (directly above) the spinning organ. The fibers were collected on a foraminous mat to "form-a fabric of about 7" onz per square yard.

Another, though more expensive, method for producing the single-component extruder multi-fiber of this invention is to split the "polymer stream" -n-. Parts later-, from which it exits the extruder, control the individual parts with individual dosing pumps or other dosing means, and direct the parts separately through a conventional conjugate fiber distribution plate until they are recombined in an extrusion orifice or spinner organ. conventional ones accept two or more separate polymer streams and keep them separate until they combine in the spinner organ Such conventional conjugate fiber distribution plates do not divide the polymer stream.

The sheath / core fibers were also successfully produced using a biconstituent blend of about 2 weight percent nylon 6 of Nyltech polypropylene Shell E5D47.

It has therefore been shown that it is possible to produce fibers according to this process in a single extruder and the same polymer resulting in a single polymer multiple-portion fiber. The process is simpler and less expensive than traditional conjugate fiber systems since it uses only one extruder. Such fibers should have the improved distribution of crystallinity through the fiber found in the conjugate fibers of two traditional extruders using the same polymer but at a lower operating and capital cost.

Although only a few example embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without departing materially from the novel teachings and advantages of this invention. Therefore, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, the media clauses plus function are intended to cover the structure described herein as carrying out the recited function and not only the structural equivalents but also the equivalent structures. Therefore even when a screw and a nail may not be structural equivalents in the sense that a nail employs a cylindrical surface to secure wooden parts together, while a screw employs a helical surface, in the environment of the fastening of the parts of wood, a nail and a screw can be equivalent structures.

Claims (21)

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

1. A process for producing a fiber comprising the steps of; liquefying a polymer, divide said polymer into at least two parts, recombining said polymer parts, and; extruding said polymer portions to form a single fiber, wherein said polymer portions have been treated in essentially identical fashion. -r _-_ ._ í.

2. The process as claimed in clause 1, characterized in that it comprises the step of cutting said fibers to form the short fibers.

3. The process as claimed in clause 2, characterized in that it comprises the step of collecting said fibers on a surface to form a short fiber fabric.

4. The process as claimed in clause 2 characterized in that said polymer is a polyester.

5. The process as claimed in clause 1 characterized in that it comprises the step of collecting said fibers on a surface to form a non-woven fiber fabric.

6. The process as claimed in clause 5 characterized in that it comprises the step of joining said fabric by a method selected from the group consisting of needle perforation, coh stitch stitching, bonding with adhesive, ultrasonic bonding and thermal bonding.

7. The process as claimed in clause 1 characterized in that it comprises the step of weaving said fibers to form = woven fiber. : - - - •• ".- .- < ~ - 'Az- ----.--. 3-c I!"': .-. "- • -" "'" i, - ~ •• ---. 'i' -: -: - -. - .-

8. The process as claimed in clause 1 further characterized because it comprises the step of weaving said fibers to form a woven fabric.

9. The process as claimed in clause 1 characterized in that said polymer is selected from the group consisting of polyamides, polyurethanes, polyvinyl chlorides, polytetrafluoroethylene, polystyrene, polyethylene terephthalate, polycarbonates, 4-methyl-1-pentene, rayon, acetates, polyesters, polyolefins, copolieter esters, block copolymers of polyether polyamide, block copolymers having the general formula ABA ', the block copolymers having the general formula AB, the ABAB tetrablock copolymers, and the polymers having polydispersity numbers below of 4.

10. The process as claimed in clause 9 characterized in that said polymer is a polyolefin and said polyolefin is an ethylene polymer.

11. . The process as claimed in clause 9 characterized in that said polymer is a polyolefin and said polyolefin is a propylene polymer.

12. The process as claimed in clause 9 characterized in that said polymer is selected from the group consisting of polyurethanes.

13. The process as claimed in clause 9 characterized in that said polymer further comprises a compatible adhesive resin.

1 . The process as claimed in clause 9 characterized in that said polymer further comprises additives selected from the group consisting of chemical repellency additives, fire retardants, photostability additives and pigments.

15. The process as claimed in clause 1 characterized in that said single fiber is in a configuration selected from the group consisting of sheath / core, islands at sea and side by side.

16. The process as claimed in clause 1 characterized in that said single fiber is a microfiber having a diameter of between about 0.5 microns and about 50 microns.

17. The process as claimed in clause 1 characterized in that said single fiber is a microfiber having a diameter of between about 10 microns and about 2-5 = raLcras .. ------: -. . ... ..-,, .._-- .-.

18. The process as claimed in clause 1 characterized in that said single fiber has a denier of between about 100 and 200.

19. A process for producing a fiber comprising the steps, in this order, of: liquefying a polymer, pumping said polymer, dividing said polymer into at least two parts, collect said polymer parts, extruding said polymer parts through a spinning organ, and; form a unique multi-part microfiber, wherein said polymer portions have been treated in essentially identical manner.

20. The process as claimed in clause 19 characterized in that it comprises the steps of collecting said fibers on a surface and thermally bonding said fibers to form a non-woven fiber fabric, wherein said polymer is propylene polymer.

21. The process as claimed in clause 19 characterized in that said division step occurs in a distribution plate adjacent to said spinning organ. SUMMARY A method is provided for producing a fiber wherein a liquefied polymer is divided into at least two streams. The streams are directed separately to a recombination point, and are extruded through, for example, a spinning organ, and are fiberized to form a single fiber having portions of each stream. The divided polymer streams are treated essentially in identical form from the point of cleavage to the point of recombination.