MXPA99012050A - Ethylene polymer compositions and article fabricated from the same - Google Patents

Abstract

The subject invention was directed to polymer compositions having improved bond performance, to a method for improving the bond performance of a polymer composition, and to fabricated articles, such as fibers and fabrics which exhibit an improved bond performance, and to other fabricated articles, including but not limited to rotationally molded articles, prepared from polymer compositions of the invention.

Description

COMPOUNDS OF ETHYLENE POLYMER AND MANUFACTURED ARTICLE THEREOF This invention relates to polymer compositions that have improved binding performance. In particular, the object of the invention also relates to a polymer composition comprising a mixture of an ethylene / α-olefin interpolymer and a high density polymer. The object of the invention further relates to the use of polymer compositions having improved bonding performance in various end-use applications, such as fibers, non-woven fabrics and articles made therefrom (eg, disposable garments or incontinence diapers, and rotationally molded articles.The fabrics have good spinnability, and result in a fabric having good bond strength and good elongation.Rotationally molded articles have good ESCR, flexible modules, Dart B Impact, and Izod impact The fiber was usually classified according to its diameter.The monofilament fiber was generally defined as having an individual fiber diameter greater than 15 denier, usually greater than 15 denier per filament.The fine denier fiber is generally refers to a fiber that has a diameter of less than 15 denier per filament.The microdenier fiber was generally defined as a fiber that has about 100 microns in diameter. The fiber can also be classified by the process by which it is manufactured, such as monofilament, fine filament of continuous winding, short fiber or of small cuts, nonwoven fused fabric, and fiber blown by fusion. A variety of fibers and fabrics have been manufactured from thermoplastics, such as polypropylene, highly branched low density polyethylene (LDPE), usually formed in a high pressure polymerization process, heterogeneously linear branched polyethylene (e.g., linear low density polyethylene). made using Ziegler's catalysis), mixtures of polypropylene and branched polyethylene, heterogeneously linear, mixtures of heterogeneously linear branched polyethylene, and ethylene / vinyl alcohol copolymers. Of the different polymers that are known to be extruded into fiber, the highly branched LDPE has not been successfully melted in the fine denier fiber. The heterogeneously linear branched polyethylene has been made in monofilament, as described in U.S. Patent 4,076,698 (Anderson et al.), The disclosure of which was incorporated herein by reference. The heterogeneously linear branched polyethylene has also been successfully produced in fine denier fiber, as described in the U.S. Patent. 4,644,045 (Foweils), U.S. Patent. 4,830,907 (Sawyer et al.), U.S. Patent. 4,909,975 (Sawyer et al.) And Patent of E.U.A. 4,578,414 (Sawyer et al.), The descriptions of which are incorporated herein by reference. Mixtures of such heterogeneously branched polyethylenes have also been made successfully in fine denier fiber and fabrics, as described in the US Patent. 4,842,922 (Krupp et al.), Patent of E.U.A. 4,990,204 (Krupp et al.) And U.S. Patent. 5,112,686 (Krupp et al.), The descriptions of which are all incorporated herein by reference. The Patent of E.U.A. No. 5,068,141 (Kubo et al.) Also discloses the manufacture of non-woven fabrics of filaments bonded by continuous heat of certain heterogeneously branched PEBDL having specific heats of melting. While the use of branched polymer blends heterogeneously produces improved fabrics, the polymers were more difficult to spin without fiber breakage. U.S. Patent 5,549,867 (Gessner et al.) Describes the addition of a low molecular weight polyolefin. A polyolefin with a molecular weight (Mz) of 400,000 to 580,000 to improve spinning. The examples shown in Gessner et al. Were directed to mixtures of 10 to 30 weight percent of a metallocene polypropylene of lower molecular weight than 70 to 90 weight percent of a higher molecular weight polypropylene using a Ziegler catalyst. Natta WO 95/32091 (Stahl et al.) Describes a reduction of bonding temperatures using mixtures of fibers produced from polypropylene resins having different melting points and which are produced by different fiber manufacturing processes, for example, melt blown and spun fibers. Stahl, et al., Claims a fiber comprising a blend of an isotactic propylene copolymer with a superior melt thermoplastic polymer. However, while Stahl et al. Provide some teachings regarding the manipulation of bonding temperature using mixtures of different fibers, Stahl, and others, do not provide guidance as to means to improve the strength of fabrics made of fabrics made of fibers that have the same melting point. U.S. Patent Application Serial No. 544,497, in the name of Lai, Knight, Chum, and Markovich, incorporated herein by reference, discloses blends of substantially linear ethylene polymers with heterogeneously branched ethylene polymers, and the use of such mixtures in a variety of end-use applications, including fibers. The fibers described preferably comprise a substantially linear ethylene polymer having a density of at least 0.89 grams / centimeters3. However, Lai et al. Describe manufacturing temperatures only above 165 ° C. In contrast, to preserve the integrity of the fibers, the fabrics were often bonded at lower temperatures, such that all crystalline materials did not fuse before or during melting. European Patent Publication (EP) 340,982 discloses two component fibers comprising a first component core and a second cover component, said second component further comprising a mixture of an amorphous polymer with at least one partially crystalline polymer. The scale described from the amorphous polymer to the crystalline polymer was from 15:85 to 00 [sic, 90]: 10. Preferably, the second component will comprise crystalline and amorphous polymers of the same general polymeric type • that the first component, with polyester being preferred. For example, the examples describe the use of an amorphous polyester and a crystalline polyester as the second component. EP 340,982, in Tables I and II, indicates that as the melt index of the amorphous polymer decreases, the mesh strength also decreases detrimentally. The polymer compositions of interest include linear low density polyethylene and high polyethylene. density that has a melt index generally in the range of 0.7 to 200 grams / 10 minutes. While such polymers have had good market success in fiber applications, fibers made from such polymers would benefit from an improvement in the strength of the fibers. union, which would lead to more resistant fabrics, and consequently, to the increase of the value of the non-woven fabrics and to the manufacturers of • articles, as well as the final consumer. However, any benefit in bond strength should not be at the cost of a detrimental reduction in spinning or a detrimental increase in gluing the fibers or fabrics to the equipment during the process. It has been found that the inclusion of a low melting point homogeneous polymer to a higher melting point polymer having an optimum melt index, can ultimately provide a calendered fabric having an improved bonding performance, while which maintains the proper fiber spinning performance. Accordingly, the object of the invention provides a fiber having a diameter of a scale of 0.1 to 50 denier which was prepared from a mixture of polymers, wherein the mixture of polymers comprises: a. from 0.5 percent to 25 weight percent (by weight of the polymer mixture) of a first polymer which was a homogeneous ethylene / α-olefin interpolymer having: i. a melt index of 0.5 to 100 grams / 10 minutes, and ii. a density of 0.855 to 0.950 grams / centimeters3, and b. a second polymer which was an ethylene homopolymer or an ethylene / α-olefin interpolymer having: i. a melt index of 0.5 to 500 grams / 10 minutes, and ii. a density which was at least 0.01 grams / centimeters3 higher, preferably at least 0.03 grams / centimeters3 higher, more preferably at least 0.05 grams / centimeters3 higher, and even more preferably at least 0. 07 grams / centimeters3 greater than the density of the first polymer, where the fiber could be joined at a temperature lower than 165 ° C. Preferably, the fiber of the invention will be prepared from a polymer composition comprising: a. at least one substantially linear ethylene / α-olefin interpolymer having: i. a melt flow ratio l? 0 l2 l 5.63, ii. a molecular weight distribution, Mp Mn, defined by the equation: Mp / Mn < (l10 / l2) -4.63, iii. a regime of critical shear stress at the onset of surface melt fracture at least 50 percent greater than the critical shear rate at the beginning of the surface melt fracture of a linear ethylene polymer having about the same l2 and Mp / Mn, and iv. a lower density of around 0.90 grams / centimeters3, and b. at least one ethylene polymer having a density greater than 0.935 grams / centimeters3. The object of the invention further provides a method for improving the bond strength of an ethylene homopolymer or an ethylene / α-olefin interpolymer having a density of at least 0.935 grams / centimeters3 and a higher melt index 0.5 to 500 grams / 10 minutes, comprising the provision in an intimate mixture therewith of 0.5 to less than 10 weight percent of a linear homogeneous or substantially linear ethylene / α-olefin interpolymer having a density of 855 at 890 grams / centimeters3 and a melt index of 0.1 to 100 grams / 10 minutes. The object of the invention further provides a polymer composition having improved bond strength, comprising: a. from 0.5 percent to less than 10 weight percent (by weight of the polymer mixture) of a first polymer which was a homogeneous ethylene / α-olefin interpolymer having: ii. a melt index of 0.1 to 100 grams / 10 minutes, and ii. a density of 0.855 to 0.890 grams / centimeters3; and b. a second polymer which was an ethylene homopolymer or an ethylene / α-olefin interpolymer, which has: i. a melt index of 0.5 to 500 grams / 10 minutes, and ii. a density which was at least 0.01 • 10 grams / centimeters3 higher, preferably at least 0.03 grams / centimeters3 higher, more preferably at least 0.05 grams / centimeters3 higher, and even more preferably at least 0.07 grams / centimeters3 higher than the density of the first polymer. The object of the invention also provides a fiber having a diameter on the scale of 0.1 to 0.5 denier which is • prepared from a polymer composition characterized by having a soluble fraction at 30 ° C, as determined from a CRYSTAF crystallization kinetic curve, of at least 0.5 percent by weight, and where the fiber could be attached at a temperature of less than 165 ° C. The object of the invention further provides a polymer composition of the invention, in the form of a fiber, cloth, nonwoven article, rotomolded article, film layer, injection molded article, blow molded article, blow molded article of injection, or extrusion coating composition. The fibers and fabrics of the invention can be produced on conventional synthetic fiber or fabric processes (eg, carded staple, fused nonwoven fabric, meltblowing, and fast spinning) and these can be used to produce fabrics having high elongation and strength. to stress, without significant sacrifice in spinning the fiber, particularly when the polymer composition contains a first polymer having an optimum melt index for the application in which it is used. The compositions of the polymer of the invention have excellent processability, preparation training of the fibers and fabrics of the invention using conventional equipment. These and other embodiments were described more fully in the detailed description, together with the following figures. Brief description of the drawings. FIGURE 1 is a bar graph illustrating the bond strength of the fabric. The elongation of the fabric and the spinning of the fibers of examples of the invention and comparative examples. FIGURE 2 is a bar graph illustrating the bond strength of the fabric, the elongation of the fabric and the spinnability of the fibers of the examples of the invention and comparative examples. FIGURE 3 is a bar graph illustrating the spinning of the fibers of the examples of the invention and a comparative example.

FIGURES 4a, 4b, 4c, and 4d are CRYSTAF crystallization kinetic curves for polymer compositions used in the preparation of the fibers of Comparative Example A, and Examples 8c, 7c, and 2b of the invention. The substantially linear branched ethylene polymers homogeneously used in the polymer compositions described herein may be interpolymers of ethylene with at least one C3-C20 α-olefin. The terms "interpolymer" and "ethylene polymer" used herein indicate that the polymer can be a copolymer, a terpolymer. Monomers usefully copolymerized with ethylene to make the substantially linear or linear branched ethylene polymers homogeneously include the C3-C20 α-olefins, especially pentane, 1-hexane, 4-methyl-1-pentane, and 1-octane. Especially preferred comonomers include 1-pentane, 1-hexane and 1-octane. Copolymers of ethylene and an α-olefin were especially preferred. The term "substantially linear" means that the base structure of the polymer substituted with 0.01 long chain branches / 1000 carbons to 3 long chains / 1000 carbons, more preferably 0.01 long chain of branches / 1000 carbons to 1 long chain of branches / 1000 carbons, and especially of 0.05 long chain of branches / 1000 carbons to 1 long chain of branches / 1000 carbons.

The long chain branches were defined herein as a branch having a greater branch length than any short chain branch which were a result of the comonomer incorporation. The long chain branching can be as long as about the same length as the length of the polymer bond. The long chain branching can be determined using 13C nuclear magnetic resonance (NMR) spectroscopy and quantified using the Randall method (Rev. Macromol. Chem. Phys C29 (2 and 3), p. 275-287) the description of which was incorporated herein by reference. In the case of substantially linear ethylene polymers, such polymers can be characterized as having: a) a melt flow ratio, 10/12 = .5.63, b) a molecular weight distribution, Mp / Mn, defined by the equation: Mp / Mn <(l10 / l2) -4.63, and c) a critical shear stress at the start of the coarse melt fracture greater than 4 x 106 dynes / cm2 or a combination thereof a critical shear rate at the beginning of the surface melt fracture at least 50 percent greater than the critical shear rate at the onset of the surface melt fracture of any linearly heterogeneously branched or heterogeneously branched linear ethylene polymer having approximately the same l2 and Mp / Mn.

In contrast to substantially linear ethylene polymers, the linear ethylene polymers lack long chain branching, ie they have less than 0.01 long chain branches / 1000 carbons. The term "linear ethylene polymers" therefore does not refer to high pressure branched polyethylene, ethylene / vinyl acetate copolymers, or ethylene / vinyl alcohol copolymers which are known to those skilled in the art to have numerous long chain branches. Linear ethylene polymers include, for example, linearly heterogeneously branched linear low density polyethylene polymers or linear high density polyethylene polymers made using Ziegler polymerization processes (e.g., US Patent 4,076,698 (Anderson et al.)) description of which was incorporated herein by reference), or homogeneous linear polymers (e.g., U.S. Patent 3,645,992 (Elston) the description of which was incorporated by reference). Both homogeneous linear and linear homogeneous ethylene polymers used to form the fibers having homogeneous branching distributions. The term "homogeneous branching distribution" means that the comonomer was randomly distributed within a given molecule and that substantially all of the copolymer molecules have the same ethylene / comonomer ratio. The homogeneous ethylene / α-olefin polymers used in this invention essentially lack a measurable "high density" fraction, as measured by the TREF technique (ie, the branched ethylene / α-olefin polymers). # homogeneous were usually characterized having less than 15 weight percent, preferably less than 10 weight percent, 5 and more preferably less than 5 weight percent of a polymer fraction with a degree of branching less than or equal to 2 methyl. / 1000 carbons). The homogeneity of the branching distribution can be measured in a variety of ways, including the measurement of SCBDI, by its acronyms in English (Short Chain Branching Distribution Index) or CDBI, for its acronym in English (Branch Distribution Distribution Index). The SXBDI or CBDI was defined as the weight percentage of the polymer molecules having a comonomer contained within 50 percent of the total average of the Molar monomer content. The CDBI of a polymer was easily calculated by a data obtained from known techniques in • the technique, such as, for example, temperature elevation elusion fractionation (abbreviated herein as "TREF") as described for example, in Wild and others, Journal of Polymer Science, Polv. Phvs. Ed., Vol 20, p. 441 (1982) (Spenadel et al.), Both descriptions of which are incorporated herein by reference. The technique for calculating CDBI was described in the U.S. Patent. 5,322,728 (Davey et al.) And the U.S. Patent. 5,246,783 (Spenadel and others) both descriptions which were incorporated herein by reference. The SCBDI and CDBI for linearly and sub-linearly homogeneously branched linear ethylene polymers were usually greater than 30 percent, and preferably greater than 50 percent, more preferably greater than 60 percent and even more preferably greater than 70 percent. percent, and more preferably greater than 90 percent. The substantially homogeneous linear and linear ethylene polymers used to make fibers of the present invention usually have a single melting peak, as measured using the differential scanning calorimetry (CBD) technique, in contrast to linearly branched heterogeneous linear ethylene polymers. , which have 2 or more melting peaks, due to the distribution of the broad branches of the branched polymer heterogeneously. The substantially linear ethylene polymers exhibit a highly unexpected flow property wherein the value of l -t or 12 of the polymer was essentially independent of the polydispersity index (i.e., Mp / Mn) of the polymer. This was in contrast to homogeneous linear ethylene polymers and heterogeneously branched linear polyethylene resins, which is why the polydispersity index should be increased in order to increase the value of 110/12 - The substantially linear ethylene polymers also exhibit good capacity of processing and low pressure drop through a spin pack, even when high shear filtration is used.

The homogeneous linear ethylene polymers useful for making the fibers and fabrics of the invention were a known class of polymers which have a linear polymer spine, without long chain branches and narrow molecular weight distribution. Such polymers were interpolymers of ethylene with at least one a-olefin comonomer of 3 to 20 carbon atoms, and were preferably copolymers of ethylene with a C3-C20 α-olefin, and were preferably copolymers of ethylene with propylene, -butane, -hexane, 4-methyl-1-pentane or 1-octane. This class of polymers is described, for example, by Elston in the U.S. Patent. 3,645,992 and subsequent processes for producing such polymers using metallocene catalysts that have been developed, as shown, for example, in PE 0 129368 E.U.A 4,937,301; Patent of E.U.A. 4,935,397; Patent of E.U.A. 5,055,438; and WO 90/07526, and others. The polymers can be made by conventional polymerization processes (e.g., gas phase, slurry, solution, and high pressure). The first polymer will be a substantially homogeneous linear or linear ethylene polymer, having a density, measured in accordance with ASTM D-792, of at least 0.850 grams / centimeters3, preferably at least 0.855 grams / centimeters3, and more preferably of at least 0.860 grams / centimeters3; and which was usually not greater than 0.920 grams / centimeters3, preferably not greater than 0.900 grams / centimeters3, more preferably not greater than 0.880 grams / centimeters3. When the second polymer was an ethylene polymer, the second polymer will have a density which was at least 0.01 grams / centimeters3, preferably at least 0.03 grams / centimeters3, more preferably at least 0.05 grams / centimeters3, and more preferably of at least 0.07 grams / centimeters3 will have a density of at least 0.880 grams / centimeters3, preferably of at least 0.900 grams / centimeters3, more preferably of at least 0.935 grams / centimeters3, still more preferably at least 0.940 grams / centimeters3 and still more preferably at least 0.950 grams / centimeters3. The molecular weight of the first and second polymers used to make the fibers and fabrics of the present invention was conveniently indicated using a melt index measurement according to ASTM D-1238, Condition 190 ° C / 2.16 kg (formally known as "Condition (E)") and also known as l2. The melt index was inversely proportional to the molecular weight of the polymer. Therefore, the higher the molecular weight, the lower the melting index, although the relationship is not linear. The melt index for the first polymer was generally at least 0.1 grams / 10 minutes, more preferably no greater than 100 grams / 10 minutes, preferably no more than 30 grams / 10 minutes, more preferably no more than 10 grams / 10 minutes, even more preferably not greater than 5 grams / 10 minutes, and more preferably not greater than 1.5 grams / 10 minutes. The melt index for the second polymer was generally at least 0.5 grams / 10 minutes, preferably 3 grams / 10 minutes, and more preferably at least 5 grams / 10 minutes. In the case of meltblown fibers, the melt index for the second polymer was preferably at least 50 grams / 10 minutes, more preferably at least 100 grams / 10 minutes, preferably not more than 1000 grams / 10 minutes. minutes, more preferably not greater than 500 grams / 10 minutes. For spunbond fibers, the melt index of the second polymer was preferably at least 15 grams / 10 minutes, more preferably at least 25 grams / 10 minutes; preferably not greater than 100 grams / 10 minutes, more preferably not greater than 35 grams / 10 minutes. For the staple fibers, the melt index of the second polymer was preferably at least 8 grams / 10 minutes, more preferably at least 10 grams / 10 minutes; preferably not greater than 35 grams / 10 minutes, more preferably not greater than 25 grams / 10 minutes. For the instant spinning fibers, the melt index of the second polymer was preferably at least 0.1 grams / 10 minutes, more preferably at least 0.5 grams / 10 minutes; preferably not more than 3 grams / 10 minutes, more preferably just 2 grams / 10 minutes. In the case of the polymer compositions for use in spin-molded articles, the melt index of the first polymer was preferably at least grams / 10 minutes, and was preferably at least 1.0 grams / 10 minutes; preferably not greater than 20 grams / 10 minutes, more preferably not greater than 10 grams / 10 minutes, even more preferably not greater than 5 grams / 10 minutes. In the case of polymer compositions for use in spin-molded articles, the melt index of the second polymer was preferably at least 3 grams / 10 minutes, more preferably at least 5 grams / 10 minutes; preferably not greater than 50 grams / 10 minutes, more • preferably not greater than 20 grams / 10 minutes, and even more preferably not greater than 10 grams / 10 minutes. Another useful measurement in characterizing the molecular weight of ethylene polymers was conveniently indicated using a melt index measurement in accordance with ASTM D-1238, Condition 190 ° C / 10 kg (formally known as "Condition (N)" • and also known as l10). The relationship of these two melting index terms was the melt flow ratio and was designated l10 / l2. For the substantially linear ethylene polymers used In compositions of polymers useful in the manufacture of fibers of the invention, the ratio lO / l2 indicates the degree of long-chain branching, that is, the larger the ratio of l or l2, the longer the long chain branch in the polymer. Substantially linear ethylene polymers may have I10 I2 variable relationships, while maintaining a low molecular weight distribution (ie, Mp / Mn from 1.5 to 2.5). Generally, the ratio of 10.0 / 2 of the substantially linear ethylene polymers was at least 5.63, preferably at least 6, more preferably at least 7, and especially at least 8. Generally, the The upper limit of the ratio of l-? 0 / l2 for homogeneously branched substantially linear ethylene polymers was 50 or less, preferably 30 or less, and especially 30 or less. Additives such as antioxidants (for example, clogged phenolics (ie, Irganox® 1010 made by Ciba-Geigy Corp.), phosphites (ie, Irgafos®) 168 made by Ciba-Geigy Corp.), additives of accumulation (by example, polyisobutylene (PIB)), antiblock additives, pigments, may also be included in the first polymer, the second polymer, or the complete polymer composition useful for making the fibers and fabrics of the invention, to the extent that they do not interfere with the properties of the improved fiber and fabric discovered by applicants. All samples of the interpolymer product and individual interpolymer components were analyzed by gel permeation chromatography (CPG) on a Waters 150 ° C high temperature chromatography unit equipped with columns of mixed porosity operating at a system temperature. of 140 ° C. The solvent was 1, 2,4-trichlorobenzene, of which 0.3 percent by weight solutions of the samples were prepared by injection. The flow rate was 1.0 milliliters / minute and the injection size was 100 microliters. Molecular weight determination was deduced using normal polystyrene narrow molecular weight distribution (from Polymer Laboratories) together with their elution volumes. The equivalent polyethylene molecular weights were determined using appropriate Mark-Houwink coefficients for polyethylene and polystyrene (as described by Williams and Ward in Journal of Polymer Science, Polymer Letters, Vol. 6, (621) 1968) to derive the following equation : IVI olietilene - a IVIpo | styrene. In this equation, a = 0.4316 and b = 1.0. The weight average molecular weight Mp and the number average molecular weight Mn were calculated in the usual manner according to the following formula: Mp = (? W, (M,)), J where W, was the fraction of weight of molecules with molecular weight Mi eluting from the column of CPG in fraction i and J = 1 when calculating Mp and j = -1 when calculating Mn. Mp / Mn of homogeneously substantially linearly branched ethylene polymers was defined by the equation: Mp / Mn < (l10 / l2) -4.63 Preferably, the Mp / Mn for both linearly homogeneous linear homogeneous ethylene polymers was from 1.5 to 2.5, and especially from 1.8 to 2.2.

A plot of apparent shear stress versus apparent shear rate was used to identify the • phenomenon of fusion fracture. According to Ramamurthy in the Journal of Rheology, 30 (2), 337-357, 1986, above a certain critical flow regime, the observed extrusion irregularities can be broadly classified into two main types: surface fusion fracture and fracture of coarse fusion. The surface melting fracture occurs under seemingly resting flow conditions and varies in detail of loss of brightness speculate for the most severe form of "shark skin". In this • description, the onset of the surface melt fracture was characterized initially by the loss of extrudate gloss in which the roughness of the extrusion surface can only be detected by increasing 40X. The regime of critical shear at the beginning of the surface fusion fracture by a substantially linear ethylene polymer was at least 50 percent • greater than the critical shear rate regime at the beginning of the surface melt fracture of a homogeneous linear ethylene polymer having the same l2 and Mp / Mn. 20 The coarse melt fracture occurs under conditions of flow at rest and varies in detail from regular (alternating rough and smooth, helical, etc.) to random distortions. For commercial acceptability (for example, in blown film products), surface defects should be minimal, if not absent.

The regime of critical shear stress at the beginning of the surface melting fracture (OSMF) and the start of the melting thickness fracture (OGMF) will be used in the present in the surface roughness changes and extrusion configurations extruded by a GER, for its acronym in English. The gas extrusion rheometer was described by M. Shida, R.N. Shroff and L.V. Cancio in Polymer Engineering Sciencie, Vol, 17, No. 11, p. 770 (1977), and in "Rheometers for Molten Plastics" by John Dealy, Published by Van Nostrand Reinold Co. (1982) on page 97, both publications which are in the present in their entirety. All the GER experiments were performed at a temperature of 190 ° C, at nitrogen pressures between 369 to 35.15 kg / cm2 using a diameter of 0.075 cm, given L / D 20: 1. A graph of apparent shear stress versus apparent shear rate was used to identify the melting fracture phenomenon. According to Ramamurthy in the Journal of Rheology, 30 (2), 337-357,1986, above a certain critical flow regime, the observed extrusion irregularities can be broadly classified into two main types: surface fusion fracture and fusion fracture gross. For the polymers described herein, Pl was the apparent viscosity (in Kpoise) of a material measured by GER at a temperature of 190 ° C, with nitrogen pressure of 175.75 kg / cm2 using a diameter of 0.19 cm, given L / D 20: 1, or corresponding apparent shear stress of 2015 x 10 dyne / cm2. The processing index was measured at a temperature of 190 ° C, under nitrogen pressure of 175.75 kg / cm2 using a diameter of 0.19 cm, given L / D 20: 1, having an angle of entry of 180 °. Exemplary constrained geometry catalysts for use in the polymerization of branched substantially linear ethylene polymers homogeneously used to make the fibers preferably include catalysts of constrained geometry as described in the application of E.U.A. Series No. 545, 403, filed on July 3, 1990; 758,654, now U.S. Patent 5,132,380; 758,660, now abandoned, filed on September 12, 1991; and 720,041, now abandoned, filed June 24, 191, and is U.S. Patent 5,272,236 and U.S. Patent 5,278,272. The polymers can be produced via a continuous controlled polymerization process (as opposed to a batchwise form) using at least one reactor, but can also be produced using multiple reactors (e.g., using a multiple reactor configuration as described in US Patent 3,914,342 (Mitchell), incorporated herein by reference), with the second polymer of ethylene polymerized at least a constructed geometry catalyst employed in at least one of the reactors at a polymerization temperature and pressure sufficient to produce the ethylene polymers having the desired properties. According to a preferred embodiment of the present process, the polymers were produced in a continuous process, as opposed to a process in the form of batches. Preferably, the polymerization temperature was from 20 ° C to 250 ° C, using restricted geometry catalyst technology. If desired, a narrow molecular weight distribution polymer (Mp / Mn of 1.5 to 2.5) having a ratio of greater than or equal to 2 (for example, 10 / l2 of 7 or more, preferably of at least 8, especially of at least 9), the concentration of ethylene in the reactor is preferably not greater than 8 weight percent of the contents of the reactor, especially not more than 4 weight percent of the reactor contents. Preferably, the polymerization was carried out in a solution polymerization process. Generally, the handling of 1 or 2 while having a relatively low Mp / Mn to produce the substantially linear polymers described herein was a function of the reactor temperature or ethylene concentration or a combination thereof. The reduced ethylene concentration and the higher temperature generally produces a greater l10 / l2. The polymerization conditions for the manufacture of substantially homogeneous linear or linear polymers used to form the fibers of the present invention were generally those useful in the solution polymerization process. Although the application of the present invention was not limited thereto. The slurry and the phase polymerization processes were also believed to be useful, as long as the catalysts and the appropriate polymerization conditions were employed. A technique for polymerizing the homogeneous linear ethylene polymers useful herein is described in U.S. Patent 3,645,992 (Elston), the disclosure of which was incorporated herein by reference. In general, the continuous polymerization according to the present invention can be completed under conditions well known in the prior art for polymerization reactions of the Ziegler-Natta or Kaminsky-Sinn type, ie, at temperatures of 0 to 250 ° C and pressures of the atmospheric at 1000 atmospheres (100 MPa). The compositions described herein may be formed by any convenient method, including dry blending of the individual components and subsequently melt mixing or premixing in a separate extruder (e.g., Banbury mixer, Haake mixer, Brabender internal mixer , or a double screw extruder). Another technique for forming the in-situ compositions was described in pending application USSN 08 / 010,958, entitled Ethylene Interpolymerizations, which was filed on January 29, 1993 in the name of Brian WS Kolthammer and Roberts S. Cardwell, the description of the which was incorporated herein by reference in its entirety. USSN 08 / 010,958 describes, inter alia, C3-C20 ethylene and alpha-olefin interpolymerizations using a homogeneous catalyst in at least one reactor and a heterogeneous catalyst in at least one other reactor. The reactors can be operated sequentially or in parallel. The compositions can also be made by fractionating a heterogeneous ethylene / α-olefin polymer into specific polymer fractions with each fraction having a narrow composition distribution (ie, branching), selecting the fraction having the specific properties, and mixing the fraction selected in the appropriate amounts with another ethylene polymer. This method was obviously not economical like the in-situ interpolymerizations of USSN 08/010, 958, but can be used to obtain the compositions of the invention. The polymer compositions described herein can be characterized by CRYSTAF crystallization techniques, more fully described together with the examples. Preferably, the polymer compositions will be characterized as having a soluble fraction of CRYSTAF at 30 ° C of at least 0.5, preferably at least 1, and more preferably at least 3 percent; preferably not greater than 20, more preferably not greater than 15, and even more preferably not greater than 10, and more preferably not greater than 8. Preferably, the fiber of the invention will be a homophilic fiber, sometimes referred to as monofilament fibers: the homophilic fibers were these fibers which have a single region (domain) and do not have other distinct polymer regions (such as bicomponent fibers). These homophilic fibers include staple fibers, spunbond fibers, meltblown fibers (using, for example, systems as described in U.S. Patent 4,340, 563 (Appel et al.), U.S. Patent 4,663,220 (Wisneski et al. ), U.S. Patent 4,669,566 (Braun), U.S. Patent 4,322,027 (Reba), U.S. Patent 3,860,369, which are hereby incorporated by reference), the gel spun fibers (e.g., the system described in the U.S. Pat. from US 4,413,110 (Kavesh et al.), incorporated herein by reference), and instant spin fibers (for example, the system described in US Patent 3,860,369). As defined in The Dictionary of Fiber & Textile Technology by Hoechst Celanese Corporation, gel spinning refers to "[a] spinning process in which the primary mechanism of solidification was gelation of the polymer solution by cooling to form a gel filament consisting of precipitated polymer and solvent The solvent removal was completed following solidification by washing in a liquid bath The resulting fibers can be drawn to give a product with high tensile strength and modules. " As defined in The Nonwoven Fabrics Handbook, by John R. Starr, Inc. produced by INDA, Association of the Nonwoven Fabrics Industry, instant spinning refers to "a modified spinning method in which the polymer solution is It extruded and the rapid evaporation of the solvent occurs in such a way that the individual filaments were separated into a form with a large amount of fibers and were recovered in a sieve to form a mesh. " The staple fibers can be melt-spun (ie, they can be extruded into the diameter of the final fiber directly without further extraction), or they can be melt-spun into a longer diameter and subsequently heated or cooled by extraction to the desired diameter using conventional techniques of fiber extraction. The novel fibers described herein can also be used as binding fibers, especially when the novel fibers have a lower melting point than the surrounding matrix fibers. In an application of the binding fibers, the bond fiber usually blends with other matrix fibers and the entire structure is subjected to heat, wherein the bond fiber fuses and joins the surrounding matrix fiber. Common matrix fibers that benefit from the use of novel fibers include, but are not limited to: poly (ethylene terephthalate) fibers; cotton fibers; nylon fibers; polypropylene fibers; other branched polyethylene fibers heterogeneously; and linear polyethylene homopolymer fibers. The diameter of the matrix fiber can vary depending on the end use application. The bicomponent fibers can also be made from the polymer compositions described herein, such bicomponent fibers have the polymer composition described herein in at least a portion of the fiber. For example, in a bicomponent cover / core fiber (i.e., in which the shell concentrically surrounds the core), the ethylene polymer blend can be either the shell or the core. Different mixtures of ethylene polymers can also be used independently as the shell and the core in some fibers and especially when the shell component has a lower melting point than the core component. Other types of bicomponent fibers were within the scope of the invention as well, and include such structures as the side-by-side (e.g., fibers having separate regions of polymers, wherein the ethylene polymer blend comprises at least one surface of the fiber). One embodiment was in a bicomponent fiber where the polymer composition described herein was provided in the shell, and a higher melting polymer, such as polyester terephthalate or polypropylene, was provided in the core. The shape of the fiber was not limited. For example, the usual fiber has a circular cross-sectional shape, but sometimes the fibers have different shapes, such as a trilobal shape, or a flat shape (ie similar to "ribbon"). The fiber described herein was not limited by the shape of the fiber. The diameter of the fiber can be measured and reported in a variety of ways. Generally, the diameter of the fiber was measured in denier per filament. Denier is a textile term which is defined as grams of fiber per 9000 meters of fiber length. Monofilaments generally refer to an extruded yarn having a denier per filament greater than 15, usually greater than 30. Fine denier fiber generally refers to a fiber having a denier of 15 or less. The microdenier (aka 5 microfiber) generally refers to fibers that have a diameter no greater than 100 micrometers. For the novel fibers described herein, the diameter can be widely varied. However, fiber denier can be adjusted to suit the capabilities of the finished article and as such, preferably will be: 0.5 to 30 denier / filament for meltblowing; from 1 to 30 denier / filament • for joining by spinning; and from 1 to 20,000 denier / filament for continuous winding filament. Fabrics made from such novel fibers include both woven and non-woven fabrics. Non-woven fabrics can be made from varied form, including linked (or hydrodynamically knotted) fabrics as described in the U.S. Patent. 3,485,706 • (Evans) and U.S. Patent 4,939,016 (Radwanski et al.), The descriptions of which are incorporated herein by reference; cardando and thermally joining the discontinuous fibers; spinning the continuous fibers in a continuous operation; or blowing by melting the fibers into fabrics and subsequently calendering or thermally bonding the resulting mesh. These different techniques of manufacturing non-woven fabrics were well known to those skilled in the art and the description was not limited to any method in particular. Other structures made from such fibers were also included within the scope of the invention, including, for example, blends of these novel fibers with other fibers (eg, poly (ethylene terephthalate) PET) or cotton). Useful non-limiting additive materials include pigments, antioxidants, stabilizers, surfactants (e.g., as described in U.S. Patent 4,486,552 (Niemann), U.S. Patent 4,578,414 (Sawyer et al.) Or U.S. Patent 4,835,194 (Bright and others), the descriptions of all of which are incorporated herein by reference). In preferred embodiments of the invention, the fabrics prepared from fabrics of the invention will exhibit an elongation of the fabric which was at least 20 percent, more preferably at least 50 percent, and more preferably at least 1200 percent greater than the fabric prepared with fibers prepared from the second non-modified polymer. In preferred embodiments of the invention, fabrics made of fibers of the invention will exhibit fabric strength which at least 5 percent, more preferably at least 10 percent, and still more preferably at least 20 percent of fabrics prepared of the prepared fiber of the second non-modified polymer. In preferred embodiments of the invention, the fibers of the invention will exhibit a yarn (maximum rpms extraction) which was not greater than 25 percent less than, preferably not more than 15 percent less than the yarn (maximum rpms extraction) of fiber prepared from the second non-modified polymer. The rpms extraction can also be correlated with the extraction pressure on a process of fused nonwoven fabric. Useful articles which can be made of polymer compositions described herein include films, fibers, and molded articles (e.g., blow molded articles, injection molded articles and rotomolded articles). The object of the invention was particularly useful in the preparation of fabrics joined in calendering rolls. Exemplary end-use items include, but are not limited to, diaper and other components of personal hygiene items, disposable clothing (such as hospital garments), durable clothing (such as insulated outer clothing), disposable towels, tablecloths, etc. . The object of the invention was also finally used in the joining of carpets or upholstery components, and in the joint or a combination thereof reinforcing other meshes (such as industrial shipping piles, enclosure and ropes, knitted wraps, pool covers) , geo-textiles and waxes). The object of the invention can also find utility in adhesive formulations, optionally in combination with one or more thickeners, plasticizers, or waxes. The first polymer and the second polymer were dry blended in the amounts indicated in the following Table One. The two components were then fed to a WPZSK30 30 mm twin screw extruder and melt blended. The spinning was conducted on a laboratory-scale spinning apparatus by Alex James (available from Alex James, Inc,). The resins to be tested were fed to a single screw extruder of 2.54 cm. X 60.96 cm, with a variation of fusion temperature from 195 ° C to 220 ° C. The fused polymer feeds a Zenith gear pump at 1,752 cc / rev. The polymer flows through a triple screen configuration (20/400/20 mesh) for all tests, for example, spinning, fabric elongation, and fabric strength except for the yarn test shown in FIG. FIGURE 3, wherein the polymer flows through a triple screen configuration (20/200/20 mesh). The polymer then exits through a rotary impeller containing 108 holes, each with a diameter of 400 μm, where L / D of the gap was 4/1. The fused polymer was extruded at 0.37 grams / minute from each well, and cooled in air by an extinguishing chamber. The fibers of the extruder move downwards 3 meters to 15.24 cm of pulley feed diameter of 15.54 cm (Ix extrusion, that is, cold extraction did not occur), then on a winder pulley with a diameter of 15.24 cm. The pulleys were graduated at 200-2200 rotations per minute (rmp). The fibers were 3.0 to 3.5 denier at these conditions. A sample was collected for 2 minutes on the second pulley, then cut from the pulley. The sample was then cut into lengths of 2.54 to 3.81 cm, known as staple fibers, and allowed to stand for a minimum of 24 hours. The aged fiber, while not required for the production of the fabrics, was used to promote the consistency of the laboratory. The spinning of the fiber samples was determined as follows. At the same temperature and pressure conditions as described for spinning to make fabric fibers, the additional fibers were drawn on the 15.24 cm diameter pulley rollers. The number of rotations of the pulley rollers per minute (rpm) was increased to 3 to 5 fiber breaks intended in the die. The rpm break was recorded as the maximum rpm at which the polymer could spin, and was repeated once or twice, with the average value reported in the Tables. This, then, was the finest denier that could be spun before the degradation in the spinning occurred from the breaking of fibers. The staple fibers were weighed as specimens of 1.25 grams, usually 4-8 specimens per sample. The 1.25 g specimens were fed to a SpinLab 580 Rotor Ring at maximum speed for 45 seconds to carder and orient the mesh, then removed, fed and re-carded for another 45 minutes. After the second carding, the 8.75 cm mesh was removed and placed on a metal feed tray of 8.75 cm by 30 cm. The thermal bonding equipment was Calendered from Laboratory Model 700 Wheeler Beloit with two rollers. The upper roller was made of a hardened chromium-plated heated steel roller with a diameter of 12.7, face of 30 cm, formed in relief in a square pattern to cover 20 percent. The lower roller was the same, except it was not formed in relief. The bonding rolls were exhibited at 70.3 kg / cm2, which were equivalent in this equipment at 153 kg per linear centimeter (pcl). (70.3 kg / cm2-28.12 kg / cm2 for lower roll to overcome the spring force = 42.18 kg / cm2 x 5,049 square centimeter cylindrical area / 8.89 cm mesh width-863.6 cm). The temperatures of the bonding rollers were separated by -15.55 ° C, with the upper rollers always being colder so that they do not cause the roller to stick in relief. The bonding rolls were exhibited at a temperature regime of 108.88 ° C to 121.11 ° C (top roll temperature) and 111.11 ° C to 139.44 ° C (lower roll temperature). The rollers rotate at 7.17 m / minute. The fiber meshes were then passed between the two rollers and removed from the opposite side of the feed area. The resulting non-woven fabrics were then cut into 2.54 cm x 10.16 cm fabric specimens. Before the analysis, each specimen was weighed, and the full weight in a computer program. The 2.54 cm x 10.16 cm specimens were placed longitudinally in a Sintech 10D with a 90 kg load cell, such that 1 cm at each end of the specimen were clamped in the upper and lower clamps. The specimens were then pulled, one at a time, in 12.5 centimeters / minutes to their breaking point. The computer then used the dimensions of the specimen and the force exerted to calculate the percentage stress (elongation) experienced by the specimen, as well as the normalized force for rupture in grams. The values were then averaged against the percentage of tension and the temperature against the normalized breaking force after plotting on the x-y axes to determine the improvements in the existing resins. For the polymer compositions of each of the Examples, except Examples 10b and 12 *, the second polymer was the polymer of Comparative Example A, a high density ethylene / octene copolymer prepared with a Ziegler Natta catalyst and having a density of 0.955 grams / centimeters3 and a melt index (12) of 29 grams / 10 minutes. For the polymer composition of Example 10b, the second polymer was the polymer of Comparative Example E, an ethylene / octane copolymer prepared with a Zigler Natta catalyst and having a density of 0.955 grams / centimeters3 and a melt index (l2). ) of 25 grams / 10 minutes. CRYSTAF crystallization kinetic curves were generated using an available CRYSYTAF instrument from Polymer Chain (Valencia, Spain). The polymer sample was dissolved, the solution was cooled to 30 ° C in the 0.2 ° C / minute regime. During cooling, the instrument takes a sample of the solution at regular intervals, and with an infrared detector measures the concentration of the polymer in the solution. A curve expressing polymer concentration against temperature was obtained. The derivative of the curve was the distribution of short chain branching. The soluble fraction reported in Table One was the amount of polymer in the solution at 30 ° C. With respect to the data shown in Table One, the overall melt index was calculated according to the following formula: l2 = [[percent by weight? * (L2) l] "1 / 3'5 + [ weight percent2 * (l2) 2]] "In addition, with respect to the data shown in Table One, the overall density was calculated according to the following formula: Density = 1 / [weight percent ^ l / density ^ + percent by weight2 * 1 / density2]. rO N3 O Ul Ül Table One • • n or n cn Table One (cont) or * Two separate experiments The second polymer was a branched heterogeneously directed ethylene / octene to have 12 of 13 grams / minute and a density of 0.951. • ro cn o cn n Table two: Comparative Examples -fc- O Several aspects of the claimed invention are further illustrated together with the figures. In particular, FIGURE 1 illustrates the improved bond performance of the fibers of the invention on fibers formed of high density polyethylene. For this FIGURE, the values reported were the average of the three values corresponding to measurements taken at the three highest temperatures before the start of stickiness of the calender roller. Table One shows the addition of 5 weight percent of a substantially linear ethylene / octene copolymer having a density of 0.870 grams / centimeters3 and a melt index (12) of 1 gram / 10 minutes (Example 7c); 5 weight percent of a substantially linear ethylene / octene copolymer having a density of 0.868 grams / centimeters3 and a melt index (12) of 0.5 grams / 10 minutes (Example 9c), and 5 weight percent of a heterogeneous ethylene / octene copolymer having a density of 0.905 grams / centimeters3 and a melt index (12) of 0.8 grams / 10 minutes (Comparative Example C) to 95 weight percent of Comparative Example A, all improved to bonding performance relative to Comparative Example A. However, as shown in FIGURE 3, 15 weight percent blends of an ethylene / octene copolymer having substantially a density of 0.870 grams / centimeters3 and an index 1 gram / 10 minute melt (Example 7b), and 15 weight percent of a substantially linear ethylene / octene copolymer having a density of 0.868 grams / centimeters3 and a melt index (12) of 0.5 grams / 10 minutes (Example 9b) with 85 percent by weight of the polymer of Comparative Example B (the same polymer of Comparative Example A, extruded through a 200 mesh screen instead of a 400 mesh screen), better retained the good spinnability of Comparative Example B than a corresponding mixture of 15 weight percent of a heterogeneous ethylene / octene copolymer having a density of 0.905 grams / centimeters3 and a melt index of 0.8 grams / 10 minutes (Ex. Comparative D) with 85 weight percent of Comparative Example B. Examples 7c, 8c and Comparative Example A of FIGURE 2 show that for manufacturing temperatures below 165 ° C, for example, the characteristics of bonding temperatures of Calender rolls, the properties were controlled by the difference of the melting point of two components, with the maximum difference that gives the maximum bond strength. For FIGURE 2, the values reported were temperatures before the start of stickiness to the calender roll. A comparison of the Examples in FIGURE 1 shows that as the melt index of the first component decreases, the strength of the fabric generally increases. FIGURE 1 further shows that incorporation of higher levels of the lower melting point components generally improves bond strength and elongation. FIGURE 1 also shows comparisons of the performance of fused nonwoven fabric that can be used to optimize a resin for yarn performance performance of fabrics. Examples 5a, 5b, and 5c exhibited a better combination of fabric strength, elongation and fiber spinning than those examples 2a, 2b, and 10. In addition, Examples 7a, 7b and 7c, exhibited a better fabric strength combination. , elongation, and fiber spinnability than those of Examples 5a, 5b, and 5c. Examples of Rotationally Molded Articles Certain compositions of the invention have further found utility in rotationally molded articles. For the Examples shown in Table Three, the compositions of the mixture were prepared by centrifugal mixing of the resin components for 30 minutes. For each of the Examples, the first polymer was a substantially linear ethylene / octene copolymer prepared in accordance with the teachings of the U.S. Patent. 5,272,236 and the Patent of E.U.A. 5,278,272, the teachings of which were incorporated herein by reference, and the second polymer was an ethylene / octene copolymer catalyzed by Ziegler Natta having a density of 0.941 grams / centimeters3 and a melt index (12) of 4.0 grains /10 minutes. The mixed compositions were processed through a 6.35 cm single screw NRM extruder to carry out a homogeneous melt blend. The extruder was set at a temperature of 176.66 ° C. The fusion mixtures were cut into pellets on a gala under a die of water pellet formation and then dried by centrifugation.

Samples of the pellet mixture were formed into molded plates according to ASTM D-1928, Method C as follows. Press platens were set at 190 ° C. When the platinums reached this temperature, the sample was placed in the press. The pressure was increased to 703 kg / cm2, said pressure was maintained for 5 minutes. While maintaining the platinum at 190 ° C, the pressure was increased to 2109 kg / cm2, this pressure was maintained for 1 minute. While the pressure of 2109 kg / cm2 is maintained, the temperature decreased at a rate of 4.62 ° C / minute. When the temperature reached 15.55 ° C, that temperature was maintained for 1 minute. The pressure was then released, the plates opened, and the sample was removed. The sample rested at normal temperature and pressure for 40 hours. The compression molded plates were tested for various physical properties, with the results shown in the following Table Three. The flexible modules were measured in accordance with ASTM D-790.

ESCR, 10 percent Igepal, was measured according to ASTM D-1693. The Izod impact (-40 percent C) was measured in accordance with ASTM D-256. The impact of Dart B was measured in accordance with ASTM D-1709.

TABLE THREE

Claims (32)

1. CLAIMS 1. A fiber having a diameter on a scale of 0.1 to 5.0 denier which was prepared from a polymer blend, wherein the polymer blend comprises: A. 0.5 to 25 weight percent (by weight of the polymer mixture) of a first polymer which was a homogeneous ethylene / α-olefin interpolymer having: i. a melt index of 0.5 to 100 grams / 10 minutes, ii. a density of 0.850 to 0.920 grams / centimeters3, and B. a second polymer which was an ethylene homopolymer or an ethylene / α-olefin ether polymer having: i. a melt index of 0.5 to 500 grams / 10 minutes, and ¡i. a density was at least 0.01 grams / centimeters3 greater than the density of the first, where the fiber could be attached at a temperature of less than 165 ° C.
2. 2. The fiber of claim 1, wherein the first polymer was provided to the mixture in an amount of 0.5 to 15 weight percent.
3. The fiber of claim 1, wherein the first polymer was an interpolymer of ethylene and at least one of C3-C20-
4. 4. The fiber of claim 1, wherein the first polymer has a density of 0.855. at 0.880 grams / centimeters3.
5. 5. The fiber of claim 1, wherein the first polymer has a melt index of 0.5 to 10 grams / 10 minutes.
6. 6. The fiber of claim 1, wherein the first polymer was a substantially linear ethylene / α-olefin interpolymer having from 0.01 to 0.3 long chain branches / 1000 carbons.
7. 7. The fiber of claim 1, wherein the first polymer was a substantially linear ethylene / α-olefin interpolymer which was further characterized as having: a. a melt flow ratio (l? o / l2) > 5.63, b. a molecular weight distribution, Mu / Mn, defined by inequality: Mp / Mn < (l10 / l2) -4.63, and c. a regime of critical shear stress at the beginning of the surface melt fracture which was at least 50 percent greater than the critical shear rate at the start of the surface melt fracture of an ethylene / a-interpolymer linear olefin having the same l2 and Mp / Mn 8.
8. The fiber of claim 1, wherein the second polymer was an ethylene polymer characterized by having: a. a molecular weight distribution, Mp / M "which was from 1.5 to 3.0, and b. when the second polymer was an ethylene / α-olefin interpolymer having a CDBI of at least 50 carbons.
9. The fiber of claim 1, wherein the second polymer was a substantially linear ethylene polymer characterized to have from 0.01 to 0.3 long chain branches / 1000 carbons.
10. 10. The fiber of claim 1, wherein the second polymer was a substantially linear ethylene polymer characterized by having: a. a melt flow ratio (I10 / I2) > 5.63, b. a molecular weight distribution, Mp / Mn, defined by the inequality: Mp / Mn < (l? o / l2) -4.63 c. a regime of critical shear stress at the beginning of the surface melt fracture which was at least 50 percent greater than the critical shear rate at the onset of the surface melt fracture of a linear ethylene polymer having the same l2 and Mp / Mn.
11. The fiber of claim 1, wherein the second polymer has a density which was at least 0.03 grams / centimeters3, greater than the density of the first polymer.
12. 12. The fiber of claim 1, wherein the second polymer has a density which was at least 0.05 grams / centimeters3 greater than the density of the first polymer.
13. The fiber of claim 1, wherein the fibers were prepared by a melt spinning process such that the fibers were meltblown fibers, meltbond fibers, carded staple fibers or flash yarns.
14. The fiber of claim 1, wherein the fibers were bicomponent fibers and the polymer blend comprises at least one outer layer of the bicomponent fiber.
15. 15. A method for improving the bond strength of an ethylene homopolymer or an ethylene / α-olefin interpolymer having a density of at least 0.935 grams / centimeters3 and a melt index of 0.5 to 500 grams / 10 minutes comprising the provision in an intimate mixture therewith of 0.5 to less than 10 weight percent of a substantially linear ethylene / α-olefin interpolymer or homogeneous linear having a density of 0.855 to 0.890 grams / centimeters3 and a melt index of 0.1 to 10 grams / 10 minutes.
16. 16. A polymer composition having improved bond strength, comprising: a. from 0.5 percent to less than 10 weight percent (by weight of the polymer blend) of a first polymer which was a homogeneous ethylene / α-olefin interpolymer having: i. a melt index of 0.1 to 100 grams / 10 minutes, ii. a density of 0.855 to 0.890 grams / centimeters3, and b. a second polymer which was an ethylene homopolymer or an ethylene / α-olefin interpolymer having i. a melt index of 0.5 to 500 grams / 10 minutes, and ¡i. a density which was at least 0.01 grams / centimeters3 greater than the density of the first polymer.
17. 17. The polymer composition of claim 16, wherein the first polymer has a density of 0.855 to 0.870 grams / centimeters3.
18. 18. The polymer composition of claim 16, wherein the second polymer has a melt index of 0.05 to 10 grams / 10 minutes.
19. 19. The polymer composition of claim 16, wherein the second polymer has a melt index of 10 to 500 grams / 10 minutes.
20. The polymer of claim 16, wherein the first polymer was a substantially linear ethylene / α-olefin interpolymer which was further characterized as having: a. a melt flow ratio (l10 / l2) > 5.63, a molecular weight distribution, Mp / Mn defined by the inequality: Mp / Mn < (l10 / l2) -4.63, and c. a regime of critical shear stress at the beginning of the surface melt fracture which was at least 50 percent greater than the critical shear rate the beginning of the melt fracture of the surface of an ethylene interpolymer / a- linear olefin that has the same l2 and Mp / Mn.
21. 21. The polymer composition of claim 16, wherein the second polymer was a homogeneous ethylene polymer characterized by having: a. a molecular weight distribution, Mp / Mn, which was from 1.5 to 3.0, and b. when the second polymer was an ethylene / α-olefin interpolymer having a CDBI of at least 50 percent.
22. 22. The polymer composition of claim 16, wherein the second polymer was a substantially linear ethylene polymer characterized by having: a. a melt flow ratio (l10 / l2) > 5.63, b. a molecular weight distribution, Mp / Mn defined by the inequality: Mp / M "< (l10 / l2) -4.63, and c. a regime of critical shear stress at the beginning of the surface melt fracture which was at least 50 percent greater than the critical shear rate at the onset of the surface melt fracture of a linear ethylene polymer having the same l2 and Mp / Mn.
23. 23. The polymer composition of claim 16, wherein the second polymer has a density which was at least 0.03 grams / centimeters3 greater than the density of the first polymer.
24. 24. The polymer composition of claim 16, wherein the second polymer has a density which was at least 0.05 grams / centimeters3 greater than the density of the first polymer.
25. 25. The polymer composition of claim 16, in the form of a fiber, rotomolded article, film layer, injection molded article, blow molded article, blow molded article of injection, or extrusion coating composition.
26. 26. A fiber having a diameter on a scale of 0.1 to 50 denier which was prepared from a polymer composition characterized by having a soluble fraction at 30 ° C, as determined from a kinetic crystallization curve of GRYSTAF, of at least 0.5 weight percent, and where the fiber could be bound at a temperature of less than 165 ° C.
27. 27. The fiber of claim 26, wherein the soluble fraction at 30 ° C was at least 1.0 weight percent.
28. 28. The fiber of claim 26, wherein the soluble fraction at 30 ° C was at least 3.0 weight percent.
29. The fiber of claim 26, wherein the polymer composition was a mixture of a first polymer which was a homogeneous ethylene / α-olefin interpolymer having a melt index of 0.5 to 40 grams / 10 minutes and a second polymer which was an ethylene homopolymer or an ethylene / α-olefin interpolymer.
30. 30. The fiber of claim 29, wherein the melt index of the first polymer was 0.5 to 10 grams / 10 minutes.
31. 31. A rotationally molded article comprising a polymer composition having improved bond strength which in turn comprises: a. from 0.5 percent to less than 15 weight percent (by weight of the polymer mixture) of a first polymer which was a homogeneous ethylene / α-olefin interpolymer having: i. a melt index of 0.1 to 100 grams / 10 minutes, ii. a density of 0.855 to 0.890 grams / centimeters3, and b. a second polymer which was an ethylene homopolymer or an ethylene / α-olefin interpolymer having i. a melt index of 0.5 to 500 grams / 10 minutes, and ii. a density which was at least 0.01 grams / centimeters3 greater than the density of the first polymer.
32. 32. The rotationally molded article of claim 31, wherein the melt index of the first polymer was 0.5 to 5 grams / 10 minutes.