MX2008005396A - Multi-layer, pre-stretched elastic articles - Google Patents

Abstract

In one embodiment the invention is an article comprising at least two layers, a first or low crystallinity layer comprising a low crystallinity polymer and a second or high crystallinity layer comprising a high crystallinity polymer. The high crystallinity polymer has a melting point as determined by differential scanning calorimetry (DSC) that is about the same or within less than 25C of the melting point of the low crystallinity polymer. The article is elongated at a temperature below the melting point of the low crystallinity polymer in at least one direction to an elongation of at least about 50%of its original length or width, to form a pre-stretched article. Preferably, the high crystallinity layer is capable of undergoing plastic deformation upon the elongation.

Description

ELASTIC ARTICLES PRE-STRETCHED, OF SEVERAL LAYERS Reference to related request This application claims the benefit, pursuant to 35 USC section 1 1 9 (c), of provisional application No. 60 / 730,338, filed on October 26, 2005. Field of the invention This invention relates to items such as movies, fabrics and fibers. In one aspect, the invention relates to elastic articles; while, in another aspect, the invention relates to pre-stretched, multilayer elastic articles. In still another aspect, the invention relates to pre-stretched, multilayer elastic articles, which comprise a low crystallinity layer comprising a low crystallinity polymer and a high crystallinity layer comprising a high crystallinity polymer. In still another aspect, the invention relates to said articles, wherein the melting point of the low crystallinity polymer is within approximately less than 25 ° C of the melting point of the high crystallinity polymer. BACKGROUND OF THE INVENTION The known co-extrusion processes involve the fusion of at least two separate polymer compositions and their simultaneous extrusion, and the immediate combination. The product of the extrusion can be cooled until the polymers have solidified, and can be rolled mechanically on a roller. He Rolling the extrusion product around a cooled roller can accelerate cooling. The extrusion product can be oriented in a controlled degree in the direction of the machine and / or in the direction transverse to it. This stretching can be effected at temperatures below the melting point of the joint extrudate. In that way articles can be formed that combine the desired properties of different polymer compositions. Generally coextruded films are formed from compositions that develop considerable mechanical strength upon cooling, by the formation of crystalline phases. Said polymeric compositions are also capable of developing increased resistance by orientation of the compositions and better alignment of the crystalline regions. Elasticity is desired in films for many applications. Examples of such applications are: in personal care products, such as diaper support sheets, diaper waist bands and diaper grip lugs; in medical applications, such as gowns and bags; and in apparel applications, such as in disposable garments. In use in the final structure, the elastic articles may provide desirable characteristics, such as helping to obtain the fit of the garments to an underlying shape. In the diaper belt bands, for example, the high elastic recovery ensures the return of the waistband to its original shape. all the use of the diaper. Elasticity is generally obtained by the use of amorphous, elastomeric polymer compositions. However, there are many difficulties and many problems associated with the processing of said compositions into articles, such as films and fibers. For example, the elasticity limits the linear speed, in particular during processing at high linear speeds, due to the tension applied to the film, which causes the film to extend, sometimes in an unstable manner. Additionally, elastic polymers are generally amorphous, high molecular weight polymers that can be difficult to process into articles such as films, fabrics and fibers. Another difficulty in processing elastic films is the thickness of the films on the roller, which causes "blockages", that is, adhesion of the film to itself. This limits the storage of the item after it has been produced. Elastic polymers can also have poor aesthetic appearance, including, for example, poor surface appearance and a hullous or sticky feel or feel. Various approaches have been made to alleviate these problems. U.S. Patent 6,649,548 describes laminated structures of non-woven fabrics with films, to impart a better feel. U.S. Patent 4,629,643 and U.S. Patent 5,814,41 3, as well as the publications of WO WO 99/47339 and WO 01/05574 describe various mechanical and of processing used to emboss or texture the surface of the film in order to increase the surface area and improve the feel. U.S. Patents 4,714, 735 and 4,820,590 disclose films comprising an elastomer, ethylene / vinyl acetate (EVA) and processing oil, which are prepared by orienting the film at an elevated temperature and fixing the film to freeze the stresses. Then the film is heated, which shrinks and forms an elastic film. In one embodiment, these references also describe films having layers of ethylene polymers or copolymers on each side of the elastic film, to reduce tackiness. By thermal stabilization of the film, it can be stabilized in its extended condition. When heat is applied, above the thermal stabilization temperature, thermal stabilization is eliminated and the film returns to its original length and remains elastic. Two heating steps are involved, which increases costs and complexity. U.S. Patent 4,880,682 discloses a multilayer film comprising an elastomeric core layer and one or more layers of thermoplastic skin (s). The elastomers are ethylene / propylene (EP), monomeric ethylene / propylene / diene (EPDM), and butyl rubber, in a structure laminated with EVA as the outer layer. After molding, these films are oriented to produce films that have a micro-undulated surface that provides a film with low luster.

Laminated, micro-textured elastomeric films having at least one adhesive layer are described in US Patents 5,354,597 and 5,376,430. U.S. Patent 4,476,180 describes blends of styrenic block copolymers based on elastomers with ethylene-vinyl acetate copolymers to reduce stickiness without excessively degrading mechanical properties. WO 2004/063270 describes an article that includes a layer of low crystallinity and a layer of high crystallinity, capable of undergoing plastic deformation when it is lengthened. The crystallinity layer includes a low crystallinity polymer and, optionally, an additional polymer. The high crystallinity layer includes a high crystallinity polymer having a melting point of at least 25 ° C above the melting point of the low crystallinity polymer. The low crystallinity polymer and the high crystallinity polymer may have compatible crystallinity. BRIEF DESCRIPTION OF THE INVENTION In one embodiment, the invention is an article comprising at least two layers: a first layer, or layer of low crystallinity, comprising a polymer of low crystallinity, and a second layer or layer of high crystallinity , which comprises a polymer of high crystallinity. The high crystallinity polymer has a melting point that is determined by differential scanning calorimetry (DSC) which is about the same, or that it is within less than 25 ° C, preferably that it is approximately equal, or is within less than 20 ° C, of the melting point of the low crystallinity polymer. The article is stretched at a temperature below the melting point of the low crystallinity polymer, at least in one direction, to an elongation of at least about 50 percent, preferably at least about 100 percent; more preferably, at least about 1 50 percent and up to as much as 300 percent or more of its original length or width, to form a pre-stretched article. Preferably the high crystallinity layer is capable of undergoing plastic deformation when it is stretched. Each layer can be a film or a non-woven article. In a second embodiment, the invention is also an article comprising at least two layers: a first layer or low crystallinity layer comprising a polymer of low crystallinity, and a second layer or layer of high crystallinity comprising a polymer of high crystallinity. However, in this embodiment, the high crystallinity polymer has a melting point, when determined by DSC, which is lower than the melting point of the low crystallinity polymer, preferably less than the melting point of the polymer. low crystallinity polymer at no more than about 50 ° C. The article is stretched at a temperature below the melting point of the low crystallinity polymer in at least one direction, at an elongation of at least about 50 percent, preferably at least about 1 00 percent, and, more preferably, at least about 1 50 percent, of its original length or width, to form a pre-stretched article. In a third embodiment, the invention is a pre-stretched, multilayer film, comprising: A. A central layer comprising: (i) first and second flat, opposite surfaces; and (ii) an elastic polymer, of low crystallinity; and B. First and second outer layers, each of which comprises: (i) first and second flat, opposite surfaces; and (ii) a polymer of high crystallinity; the second flat surface or lower surface of the first outer layer being in intimate contact with the first surface or upper planar surface of the central layer, and the first surface or upper planar surface of the second outer layer being in intimate contact with the surface bottom flat or second flat surface of the central layer; with the proviso that: (i) the melting point of the high crystallinity polymer is lower than the melting point of the low crystallinity polymer; or (ii) the melting point of the high crystallinity polymer is not more than 25 ° C above the melting point of the low crystallinity polymer. The high crystallinity polymer of the first outer layer may be equal to or different from the high crystallinity polymer of the other outer layer. Preferably, the polymer of the core layer is a copolymer of propylene, and the polymer of the outer layer is typically a polyolefin. Typically, the polymer of the outer layer of the first and second outer layers is the same. When preparing, the film is stretched or activated, typically at an elongation of at least about 50 percent, preferably at least about 1 00 percent and, more preferably, at least about 1 50 percent and up to 300 percent or more of its original length or width. In a fourth embodiment, the invention is a process for forming a pre-stretched, multilayer film comprising at least two layers: a first layer or low crystallinity layer comprising a low polymer. crystallinity, and a second layer, or layer of high crystallinity, comprising a polymer of low crystallinity. The high crystallinity polymer has a melting point, as determined by DSC, which is approximately equal to the melting point of the low crystallinity polymer, or which is within less than 25 ° C of said melting point. The process comprises the steps of: (1) forming the film; and (2) lengthening the film by at least n one direction to at least about 50 percent, preferably at least about 1 00 percent; more preferably, at least about 1 50 percent and up to 300 percent or more of its original length or width. Preferably, the film is stretched at a temperature below the melting point of the high crystallinity polymer; more preferable, at a temperature lower than melting point of the low crystallinity polymer. The lengthening step produces a film with a storiness value of more than zero percent; typically at least 10 percent; more typically, at least 25 percent; and still more typically, of at least 50 percent. In a fifth embodiment, the invention is the article described in the first and second embodiments in the form of a fiber, preferably a two-component fiber. Preferably, the low crystallinity polymer comprises at least a portion of the surface of the fiber, especially in fibers having a sheath / core configuration, side by side, crescent, trilobal, islands at sea, or flat . Fibers in which the high crystallinity polymer has been plastically deformed are particularly preferred. Other embodiments of the invention include the article in the form of a woven fabric, a non-woven fabric, or a woven / non-woven mixed media.; films comprising four or more layers; garments and other structures made from the articles, for example, diaper support sheets and elastic ears for diapers, hospital clothes, etc.; interlaced items; articles that contain charges and the like. Methods for forming a non-woven laminate structure are known in the art, for example, from US Patents 5,336,545 and 5,514,470. In all embodiments of this invention, preferably the percentage difference in weight of the crystallinity between the polymers of high crystallinity and low crystallinity, is at least about 1 percent, preferably at least about 3 percent and, more preferably, at least about 5 percent. It is preferred that the percentage difference in weight of the crystallinity between the polymers of high crystallinity and low crystallinity be not more than about 90 percent; preferably, not greater than about 80 percent and, more preferably, not greater than about 70 percent. Brief description of the drawings Figure 1 is a graph of the previous stretch level on permanent deformation, after a 50 percent hysteresis test. Figure 2 is a graph of the effect of the previous stretch level on permanent deformation, after a hysteresis test at 1 00 percent. Figure 3 is a graph of the effect of the previous stretch level on permanent deformation, after a 150 percent hysteresis test. Figure 4 is a schematic representation of a three layer film of this invention. Figure 5 is a schematic representation of a five-layer film embodiment of this invention, comprising a core layer, two inner skin layers and two outer skin layers.

Figure 6 is a schematic representation of an alternative embodiment of a five-layer film of the present invention, comprising two outer skin layers and two center layers, separated by a layer of inner skin. Detailed description of the invention "Low crystallinity", "high crystallinity" and other similar terms, are not used in an absolute sense; rather, they are used in a sense that relates them to one another. Typical polymers of high crystallinity include: linear low density polyethylene (LLDPE), low density polyethylene (LDPE), high density polyethylene (H DPE), homopolypropylene (h PP), propylene random copolymer (RC P) and others Similar. The low crystallinity propylene copolymers, which are of particular interest, include: propylene / ethylene, propylene / 1-butene, propylene / 1-hexene, propylene / 4-methyl-1-pentene, propylene / 1-ketene, propylene / ethylene / 1-butene, propylene / ethylene / EN B, propylene / ethylene / 1-hexene, propylene / ethylene / 1-ketene, propylene / styrene and propylene / ethylene / styrene. Representative of these copolymers are the VERSI FY ™ propylene elastic copolymers, manufactured and sold by The Dow Chemical Company. These copolymers are made using a metal-centered heteroaryl ligand catalyst, in combination with one or more activators, for example, an alumoxane. In certain embodiments, the metal is one or more of hafnium and zirconium. The VERSI FY ™ propylene elastic copolymers and copolymers made in a similar way are described more completely in US Patents 6,906, 160, 6,91 9,407 and 6,927,256. This annotation is made in an article comprising two layers, one of which comprises a polymer h PP with a crystallinity of 50 percent, and another layer comprising a polymer h PP with a crystallinity of 65 percent, the layer and the polymer having a crystallinity of 50 percent in the low crystallinity layer, and the polymer in relation to the layer and polymer with a crystallinity of 65 percent, which is the layer and the polymer of high crystallinity. The term "polymer" includes, in general, but not limited to, homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers; the terpolymers, etc. , and the mixtures and modifications of them. Additionally, unless specifically limited otherwise, the term "polymer" will include all possible geometric configurations of the material. These configurations include, but are not limited to,, the isotactic, syndiotactic and random symmetries. The terms "polypropylene-based plastomers" (PBP) or "propylene-based elastomers" (PBE) include propylene copolymers, with reactor quality, having a heat of fusion less than about 10 J / g and one MWD. greater than 3.5. In general, PBPs have a heat of fusion less than about 1000 J / g, while PBE generally have a heat of fusion less than about 40 J / g. The PBPs typically have a weight percent ethylene in the range of about 3 to about 15 percent by weight; the elastomeric PBEs having from about 10 to about 15 weight percent ethylene. All percentages specified here are percentages by weight, unless otherwise specified. The copolymer is a PBP or a PBE having an MWD of less than about 3.5, and having a heat of fusion of less than about 90 J / g, preferably less than about 70 J / g; more preferable, less than about 50 J / g. When ethylene is used as the comonomer, the reactor-grade propylene-based elastomer or plastomer has from about 3 to about 1 5 percent ethylene, preferably from about 5 to about 14 percent ethylene; more preferable, about 9 to about 14 percent ethylene, by weight of the propylene-based elastomer or plastomer. Suitable propylene-based elastomers and / or plastomers are taught in WO 03/040442. They are of particular interest for use in the present invention PBE of reactor quality that have MWD less than about 3.5. The term "reactor quality" is defined in U.S. Patent 6,010, 588 and, in general, refers to a polyolefin resin whose molecular weight distribution or polydispersity has not been substantially altered after the polymerization. Although the remaining units of the propylene copolymer are derived from at least one comonomer, such as ethylene, an α-olefin of 4 to 20 carbon atoms, a diene of 4 to 20 carbon atoms, a styrenic compound and the like , preferably the comonomer is at least one of ethylene and an alpha-olefin of 4 to 12 carbon atoms, such as 1 -hexene or 1-ketene. Preferably the remaining units of the copolymer are derived solely from ethylene. The amount of comonomer other than ethylene, present in the propylene-based elastomer or plastomer, is a function, at least in part, of the comonomer and the desired fusion heat of the copolymer. If the comonomer is ethylene, then typically the units derived from the comonomer constitute no more than about 1.5 percent by weight of the copolymer. The minimum amount of units derived from ethylene is typically at least about 3, preferably, at least about 5 and, more preferably, at least about 9 percent, based on the weight of the copolymer. If the copolymer comprises at least one other comonomer other than ethylene, then the composition would have a heat of fusion which would be approximately on the scale of a propylene-ethylene copolymer with about 3 to 20 percent ethylene. Polymers with approximately similar crystallinity, and with approximately equal crystal morphology, are preferred for use them in a non-woven. The propylene-based elastomers or plastomers of this invention can be made by any process, and include copolymers made by Ziegler-Natta catalysis, CGC (catalysed of restricted geometry), metallocene and of metallocene-free heteroaryl ligand, centered on the metal. Exemplary propylene copolymers include the propylene / ethylene copolymers obtainable from The Dow Chemical Company. The density of the propylene-based elastomers or plastomers, used in the practice of this invention, is typically at least about 0.850, or at least about 0.860, or at least about 0.865 grams per cubic centimeter (g / cm3). , when measured by ASTM D-792. The weight average molecular weight (Mw) of the propylene-based elastomers or plastomers of the present invention can vary widely; but it is typical that it is between approximately 10,000 and 1,000,000 (it being understood that the only limit on the minimum or maximum Mw is fixed by practical considerations). For homopolymers and copolymers used in the manufacture of films, the melt flow rate (M FR), when measured by ASTM D-1 238, condition L (2.1 6 kg, 230 ° C), typically goes from about 0.1 0 to 1 0 for the blown film processes, and about 0.50 to 50 for the molded film processes.

The polydispersity of the propylene-based elastomers or plastomers of the present invention is typically between about 2 and about 3.5. "Narrow polydispersity", "narrow molecular weight distribution", "narrow MWD" and other similar terms, mean a ratio (Mw / M n) of weight average molecular weight (Mw) to number average molecular weight (Mn) of less than about 3.5, or less than about 3.0 or less than about 2.8, or less than about 2.5, or less than about 2.3. In aspects of several layers of this invention, it is generally desirable that the viscosity of the various layers be approximately equal for given shear rates and given temperatures. Gel Permeation Chromatography The molecular weight and molecular weight distribution of the polymers are determined using gel permeation chromatography (G PC) in a high temperature chromatography unit PL-G PC-220 from Polymer Laboratories, eq. uipada with four columns of mixed, linear bed (Polymer Laboratories (particle size of 20 micras)). The oven temperature is 1 60 ° C, with the hot zone of the auto-sampler at 1 60 ° C and the warm zone at 145 ° C. The solvent is 1, 2,4-trichlorobenzene containing 200 ppm of 2,6-di-tert-butyl-4-methylphenol. The flow rate is 1.0 milliliter / min uto, and the injection size is 1000 microliters. Approximately 0.2 percent by weight solutions of the samples for injection, dissolving the sample in 1,2,4-trichlorobenzene purged with nitrogen, containing 200 ppm of 2,6-di-tert-butyl-4-methylphenol, for 2.5 hours at 160 ° C, with moderate mixing. The molecular weight determination is derived using ten polystyrene standards, with narrow molecular weight distribution (from Polymer Laboratories, EasiCel PS1, ranging from 580 to 7,500,000 g / mol), together with their elution volumes. The equivalent molecular weights of polypropylene are determined using Mark-Houwink coefficients for polypropylene (as described by Th. G. Scholte, NIJ Meijerink, HM Schoffeleers and AMG Brands, J. Appl. Polym. Sci., 29, 3763- 3782 (1984)) and for polystyrene (as described by EP Otocka, RJ Roe, NY Hellman, PM Muglia, Macromolecules, 4, 507 (1971)) in the Mark-Houwink equation:. { N.}. = KMa where Kpp = 1.90E-04, app = 0.725 and Kps = 1.26E-04, aps = 0.702. The PBE for use in the present invention ideally have an MFR of 0.1 to 600 g / 10 minute. The MFR is measured for the copolymers of propylene and ethylene and / or one or more alpha-olefins of 4 to 20 carbon atoms according to ASTM D-1238, condition L (2.16 kg, 230 ° C). For a molded film, preferably the melt flow rate of at least one of the layers is at least about 2 g / 10 minutes and, more preferably, approximately 5 to 50 g / 1 0 minutes. For blown films, preferably at least one of the layers has a melt flow rate of less than about 9 g / 10 minutes and, more preferably, less than about 6 g / 10 minutes. The article A mode of the invention includes an article comprising a layer of low crystallinity and a layer of high crystallinity; the high crystallinity layer being capable of undergoing plastic deformation by elongation. The "elongation" is a uniaxial or biaxial stretching of the article in a sufficient gage to cause the plastic deformation of the high crystallinity layer. The degree of plastic deformation and the amount of elongation required to plastically deform an article can be determined with ease by determining the amount of surface roughness and / or increasing the turbidity value. The total amount of polymer of low crystallinity and high crystallinity in the article can be varied conveniently; but typically the article consists mainly (more than 50 weight percent) of the two polymers. In one embodiment, the article comprises at least about 75 weight percent; while in another embodiment it comprises at least about 90 weight percent. In certain embodiments of the invention the article consists, except for various low levels of additives, of essentially 1 00 weight percent of the two polymers. The high crystallinity polymer is typically present in the article, in relation to the combined weight of the polymers of high low crystallinity, to less than about 20 percent, preferably, less than about 10 percent; more preferably, less than about 6 percent, and up to a low level of about 2 percent by weight. The high crystallinity polymer is typically present in the article, relative to the combined weight of the high and low crystallinity polymers, in an amount of at least about 45 percent, preferably at least about 60 percent, more preferably, at least about 80 percent and up to a high level of about 98 weight percent. Before stretching, the article has poor elastic and hysteresis characteristics, due to the influence of the layer or layers of high crystallinity. However, when the article is stretched beyond the plastic deformation point of the layer or the high crystallinity layers, the elastic and hysteresis properties are improved, for example, the effect of the pre-stretching of the films above 50 ° C. percent of effort, gives as a result a lower posterior permanent deformation (see Figures 1 to 3).

The dimensional profile (surface roughness) and the increase in the value of your texture can be used by someone who has experience in the matter, to determine if an article is plastically deformed. The turbidity is measured according to ASTM D 1 003, using a HazeGard PLUS gauge, obtainable from BYK Gardner, from Melville, New York, E. U. A., with a light source C I É lluminant C. The plastically deformed articles according to the invention have a haze value of more than about 70 percent, or more than about 80 percent, or more than about 90 percent. The plastically deformed articles have an increased turbidity value, compared to the article before being elongated. Although not wishing to be limited to one theory, it is believed that the change (increase) in turbidity is caused by an increase in surface roughness. It is believed that the surface roughness is caused by the differential recovery behavior, after deformation. During deformation, it is believed that the high crystallinity and low crystallinity layers extend in a similar manner, but that, upon release, there is a differential recovery behavior between the higher and lower crystallinity layers. It is believed that the lower recovery (greater permanent deformation) of the layer of greater crystallinity, and the retraction force of the layer of lower crystallinity produce a mechanical instability and result in a structure that can be described as corrugated, micro-corrugated , micro-textured or large ulosa. The surface roughness of the article can be measured by several instruments, capable of accurate surface roughness measurements. One of these instruments is the Su rfcom 1 1 0B, manufactured by Tokyo Seimitsu Company. The instrument Your rfcom contains a Diamond tip that moves across the surface of the sample. The sample can vary in its hardness from metal to rubber, going through the plastic. The instrument records the surface irregularities in the section through which the tip moves. The surface roughness is quantified using a combination of three factors: Ra (pm), the arithmetic mean, which represents the distance of the surface profile of the extruded product from a midline; Ry (m), the sum of the height of the maximum peak from a median line, and the depth of the deepest valley, from a median line; and Rz (um), the sum of two means that are the average height of the five highest peaks from a median line, and the average depth of the five deepest valleys, from a midline. The combination of Ra values, Ry and Rz characterizes the surface profile of the film. When comparing the values of the non-elongated film, against the values of the plastically deformed films, the increase in the roughness of the film surface and, therefore, the effectiveness of the orientation process can be determined. In some embodiments the article is extended in at least one direction to at least about 1 00 percent, or to at least about 1 50 percent of its original length or width. In general, the article is extended to a temperature below the melting temperature of the low crystallinity polymer or the high crystallinity polymer. This "pre-stretch" step is accomplished by any means known to the subject matter experts; however, they are particularly suitable in particular for the methods of activating the MD orientation (in the machine direction and / or CD (in the transverse direction), including ring bearing, MD orientation (M OD) and a bonded lamination process This stretch is a "pre-stretch" in the context that the film will probably retract in its final use, for example, in packaging or boarding or hygiene applications. In the case of articles of the invention alone, or in the articles of the invention in laminated form, this process can also be used in elastic non-wovens.The article is typically formed using any manufacturing process, such as a film-coated process. extrusion or a molded film process, separated or recovered from that process, and then pre-stretched, preferably the article is pre-stretched after the article has solidified (more preferable, though not necessarily, crystallized). It does not favor the present invention to operate at the melting point of the layer of lower crystallinity, nor above that point, as is typical, for example, in the double bubble orientation process (Pahike) and because, in general, , will not produce the desired structures. Preferably the layer of lower crystallinity has reached its maximum crystallinity before the pre-stretching process. The present invention is especially useful for film converters which must store the elastic film in rolls, before assembly to laminated structures. A particular challenge for conventional elastic film is the formation of blockers. This invention serves to remedy that problem. The present invention is also useful during the conversion to reduce the coefficient of friction and to increase the stiffness of the film during transportation, cutting, assembly and other steps. Other applications include support sheets for elastic diapers, feminine hygiene films, elastic strips, elastic structures in gowns, sheets and the like. In a particular embodiment, the article is formed by coextruding the low crystallinity layer and the high crystallinity layer, before elongation. The article can be oriented optionally in the machine direction (M D) or in cross direction (TD) or in both directions (biaxially) using conventional equipment and processes. The orientation can be carried out in a separate step, before the elongation step described below. In this way an article oriented as an intermediary product can be prepared, which is then lengthened later in a separate step. In this embodiment, the orientation is preferably carried out in such a way that a minimum of plastic deformation of the high crystallinity layer occurs. Alternatively, the orientation and elongation can be carried out until the plastic deformation, in a single step. In some embodiments, the low crystallinity layer is in contact or in intimate contact with the high crystallinity layer. The term "in contact" means that there is sufficient interfacial adhesion provided, for example, by compatible crystallinity, so that the adjacent polymer layers do not delaminate even after orientation and / or elongation. The term "in intimate contact" means that essentially a complete flat surface of one layer is in adherent relation with a flat surface of another layer. Typically, the two flat surfaces are coterminal with each other. In certain embodiments, the low crystallinity layer adheres to the high crystallinity layer by the use of conventional materials, such as adhesives. Certain embodiments of the invention are generally described with reference to Figures 4 to 6. The purpose of these figures is to illustrate certain modalities only, and are not intended to limit the scope of the invention. In the drawings, similar numbers are used to designate similar parts in all of them. Figure 4 is a schematic drawing of a three layer film 1 0, comprising a first layer, or outer layer 1 1, the second surface or lower surface of which is in intimate contact with the upper flat surface or first flat surface of the center or interior layer 12. The lower surface or second plane surface of the center layer 1 2, which is opposite to the upper flat surface of the center layer 12, is in intimate contact with an upper surface or first flat surface of the second skin layer or outer layer 1 3.

The term "flat surface" is used differently from "edge surface". If it has a rectangular shape or configuration, a film will comprise two opposite flat surfaces, bordered by four edge surfaces (two opposite pairs of edge surfaces, intersecting each pair with the other pair, at right angles). The lower planar surface of the first skin layer is adapted to join or adhere to the upper planar surface of the center layer, and the upper planar surface of the second skin layer is adapted to be attached or ad injured to the lower planar surface of the center layer. In practice, the first and second skin layers are typically of the same composition and, as such, are interchangeable. Likewise, the upper and lower flat surfaces of both the skin layers and the center layers, in functional sense, are essentially the same and, in such a way, each layer can be "turned over", ie the upper flat surface can serve r as a lower flat surface, and vice versa. The films can be of any size and shape and, therefore, the flat and edge surfaces can be, for example, thin or thick, polygonal or circular, etc. Typically, the film is in the form of an extended ribbon. Figure 5 illustrates a film of the present invention in a five layer format. In this embodiment, the central layer 1 2 and the skin layers 1 1 and 1 3 remain in the same relationship as illustrated in Figure 4, except that the upper flat surface of the skin layer 1 1 is in intimate contact with the flat surface I Bottom of the first outer skin layer 14; and the lower full surface of the skin layer 1 3 is in intimate contact with the upper flat surface of the second outer skin layer 1. Figure 6 illustrates a five layer alternative film of the present invention. In this embodiment, the central layers 1 2 and 1 3 are separated by the inner skin layer 1 3; while the upper flat surface of the central layer 1 2 is in intimate contact with the lower flat surface of the outer skin layer 1 1, and the lower flat surface of the central layer 1 6 is in intimate contact with the flat surface thereof. above the outer skin layer 1 7.

Other film constructions are possible, for example, from 4 layers, 6 layers, 7 layers and more (none of which is shown), and are included within the scope of the present invention. In each film construction of this invention, each core layer is joined to its flat surfaces by a skin layer. The films of the present invention can be prepared by any conventional process and, typically, are formed by separately extruding the individual layers, using conventional extrusion equipment; and then the respective flat surfaces of the individual layers are joined or laminated, with each other, using conventional techniques and equipment, for example, by feeding the individual layers together, in aligned form, through a set of pressure rollers. Skin layers typically comprise less than 30 per one hundred (%) by weight; preferably less than 20 weight percent and, more preferably, less than 10 weight percent; of a three-layer film consisting of a center layer and two layers of skin. Each layer of skin is typically the same as the other layer of skin in thickness and weight, although one layer of skin may vary from the other of either or both of those measurements. In another embodiment, the article is a film in which the high crystallinity layer forms a skin layer. In a different embodiment, the high crystallinity layer is intermediate between the low crystallinity layer and another type of skin layer, such as any conventional polymeric layer. In yet another embodiment, high crystallinity layers are present on both sides of the low crystallinity layer. In this modality, the two layers of high crystallinity can be the same or different in their composition, and equal or different in their thickness. In another embodiment, the article includes, in sequence: a high crystallinity layer, a low crystallinity layer and an additional layer of low crystallinity. In this embodiment, the two layers of low crystallinity can be the same or different in their composition and equal or different in their thickness. The article can comprise as many layers as desired. The high crystallinity layer, or one or more layers of low crystallinity may also form a skin layer, and may be adapted to be melt bonded onto a substrate. The skin layers, different from the high crystallinity layer and the layer of low crystallinity, they can also be adapted for fusion adhesion on a substrate. Non-polymeric additives that can be added to one or more layers include: processing oil, flow improvers, fire retardants, antioxidants, plasticizers, pigments, vulcanizing or curing agents, vulcanization or cure accelerators; Curing retarders, processing aids, flame retardants, thickener resins, and the like. These compounds may include fillers and / or reinforcing materials. These include: smoke smoke, clay, talcum, calcium carbonate, mica, silica, silicate and combinations of two or more of these materials. Other additives that can be used to increase the properties include anti-blocking agents and coloring agents. Lubricants, mold release agents, nucleating agents, reinforcements and fillers (including granular, fibrous or powder materials) can also be used. Nucleating agents and fillers tend to improve the stiffness of the article. The exemplary lists provided above are not exhaustive of the various classes and the various types of additives that may be employed with the present invention. The overall thickness of the article is not particularly limited, but is typically less than 20 thousandths of a pound (508 microns), often less than 10 thousandths of an inch (254 microns). The thickness of any of the individual layers can vary widely, and are typically determined by the process, use and economic considerations. In a particular embodiment, the high crystallinity layer comprises medium density or high density polyethylene, and the low crystallinity layer comprises a plastomer. In another particular embodiment, the high crystallinity layer and the low crystallinity layer comprise syndiotactic copolymers having relatively high and low crystallinity. In another particular embodiment the high crystallinity layer comprises isotactic polypropylene and the low crystallinity layer comprises a polypropylene elastomer having relatively low levels of isotactic crystallinity. The low crystallinity layer The low crystallinity layer has a level of crystallinity that can be detected by differential scanning calorimetry (DSC), but has elastomeric properties. The low crystallinity layer is sufficiently elastic to allow the extension of the high crystallinity layer up to and beyond the point of plastic deformation, without substantial loss of its elastic properties. The low crystallinity layer comprises a polymer of low crystallinity and, optionally, at least one additional polymer. In certain embodiments, the low crystallinity layer may be stretched 50 percent, 1 00 percent, 1 50 percent, 300 percent and up to 500 percent or more of its length or width before stretching. The low crystallinity polymer The low crystallinity polymer of the present invention is a soft, elastic polymer with a moderate level of crystallinity due to the stereo-regular propylene sequences. The low crystallinity polymer may be: (A) a homopolymer of propylene, in which the stereo-regularity is interrupted in some way, such as by regio-inversions; (B) a random copolymer of propylene, wherein the stereo-regularity of propylene is altered at least in part by comonomers; or (C), a combination of (A) and (B). In a particular embodiment, the low crystallinity polymer is a copolymer of propylene and one or more comonomers selected from: ethylene, alpha-olefins of 4 to 12 carbon atoms, and combinations of two or more such comonomers. In a particular aspect of this embodiment, the low crystallinity polymer includes units derived from the comonomer or the comonomers, in an amount ranging from a lower limit of about 2 percent, 5 percent, 6 percent, 8 percent, or 10 percent by weight, to an upper limit of about 28 percent, 25 percent or 20 percent by weight. This embodiment also includes units derived from propylene, which are present in an amount ranging from a lower limit of about 72 percent, 75 percent or 80 percent by weight, to an upper limit of approximately 98 percent, 95 percent. one hundred, 94 percent, 92 percent or 90 percent by weight. These percentages by weight are based in the total weight of the units derived from propylene and the units derived from the comonomer, that is, based on the sum of the percentage by weight of the units derived from propylene and the percentage by weight of the units derived from the comonomer that is equal at 1 00 percent. The embodiments of the invention include low crystallinity polymers having a heat of fusion, when determined by DSC, ranging from a lower limit of about 1 July / g bouquet (J / g) or 3 J / g or 5 J / go 1 0 J / go 1 5 J / go 20 J / g, up to an upper limit of approximately 1 25 J / go 1 00 J / go 75 J / go 57 J / go 50 J / go 47 J / go 37 J / g or 30 J / g. The "heat of fusion" is measured using DSC which can be measured using the following method: Without wishing to be bound by any theory, it is believed that the low crystallinity polymeric embodiments of the invention have generally isotactic crystalline propylene sequences, and He believes that the previous heats of fusion are due to the fusion of these crystalline segments. The crystallinity of the low crystallinity polymer can also be expressed in terms of percent crystallinity. The thermal energy for the maximum order of polypropylene is measured as 1 65 J / g. That is, it is taken as if the 1 00 percent crystallinity equals 1 65 J / g. In that way, the heats of fusion previously discussed suggest that the low crystallinity polymer has a polypropylene crystallinity within the scale that has an upper limit of about 35 percent, or 26 percent, or 22 percent, or 1 7.5 percent; and a lower limit of approximately 2.6 percent, or 4.4 percent or 6.1 percent, or 7 percent. The level of crystallinity at the melting point can be reflected.

The "melting point" is determined by DSC, as previously discussed. The low crystallinity polymer, according to one embodiment of the present invention, has one or more melting points. Typically, a sample of the polypropylene copolymer will show multiple melting peaks, adjacent to the main peak, which are considered jute as a single melting point. The maximum thermal flow rate of these peaks is considered the melting point. The low crystallinity polymer can have a melting point, determined by DSC, which varies from an upper limit of about 1 30 ° C or 1 05 ° C or 90 ° C or 80 ° C or 70 ° C, up to a limit lower of approximately 20 ° C or 25 ° C or 30 ° C or 35 ° C or 40 ° C or 45 ° C. The low crystallinity polymer can have a weight average molecular weight (Mw) of from about 1,000,000 to about 5,000,000 g / mol, or from about 20,000 to about 1,000,000 g / mol, or from about 80,000 to about 500,000 g / mol, and a molecular weight distribution Mw / M n (MWD) sometimes called "polydispersity index" (FDI) ranging from a lower limit of about 1.5 or 1.8, to an upper limit of about 40 or 20 or 1 0 or 5 or 3. The Mw and the MWD can be determined by a variety of methods, including those of U.S. Patent 4,540,753 of Cozewith and co-inventors, and references cited by Cozewith and co-inventors, or methods found in Verstrate and co-authors, Macromolecules, volume 21, page 3360 (1988). In some embodiments of the present invention the low crystallinity polymer has a Mooney viscosity M L (1 + 4) 1 25 ° C of about 1000 or less, or 75 or less, or less, or 30 or less. The Mooney viscosity is measured as M L (1 +4) 1 25 ° C in accordance with ASTM D 1646, unless otherwise specified. In a preferred embodiment of the present invention, the propylene-based elastomers or plastomers are further characterized by having at least one of the following properties: (i) 13C NMR peaks which correspond to a regio-error of approximately 14.6 and approximately 5.7 ppm; the peaks being of approximately equal intensity; (ii) a DSC curve with a Tme which remains essentially the same and a Tmax decreasing as the amount of comonomer increases, ie the units derived from ethylene and / or the comonomer or the unsaturated comonomers present in the copolymer; (iii) a B value, when measured according to the Koen ig method (described below) greater than about 1.03, when the comonomer content, ie the units derived from the comonomer different from propylene, is at least about 3 weight percent; and (iv) an asymmetry index, Six, greater than approximately -1.20. Typically, the copolymers of this embodiment are characterized by at least two, preferably three, and more preferably the four properties mentioned. In another embodiment of this invention, these copolymers are further characterized by having also (v) an X-ray diffraction pattern, when the sample is slowly cooled, which reports more crystals in gamma form than a comparable copolymer, prepared with a catalyst of Ziegler-Natta (ZN). Each of these properties and their respective measures is described in detail in U.S. Patent 6,943,21 5, although, for the purposes of this invention, the B value and the 13C RM N are described below. The value B "Value B" and other similar terms mean the ethylene units of a copolymer of propylene and ethylene, or a copolymer of propylene, ethylene and at least one unsaturated comonomer, which are distributed through the polymer chain, a non-random way. The B values vary from 0 to 2. The higher the value B, the more alternating will be the comonomer distribution in the copolymer. The smaller the B value, the more blocker or rupada will be the comonomer distribution in the copolymer. The high B values of the polymers made using a metal-centered heterolarilic ligand catalyst, without metallocene, such as described in US Patent No. 6,960, 635, typically they are at least about 1.03, when determined according to the Koenig method (Spectroscopy of Polymers, American Chemical Society, Washington, DC, E.U. A., 1 992), preferably at least about 1.04; more preferable, at least about 1.05 and, in some cases, at least about 1.06. This is very different from propylene-based copolymers, typically made with metallocene catalysts, which generally exhibit B-values less than 1.00, typically, less than 0.95. There are several ways to calculate the B value; The method described below uses the method of Koenig, J. L., in which a B value of 1 designates a perfectly random distribution of comonomer units. The B value, as described by Koenig, is calculated as follows. B is defined for a propylene / ethylene copolymer, as follows: where f (EP + PE) = the sum of the fractions of the EP and PE dyads; and Fe and Fp = the mole fraction of ethylene and propylene in the copolymer, respectively. The daily fraction of the triad data can be derived according to: f (EP + PE) = [EPE] + [EPP + PPE] / 2 + [PEP] + [EEP + PEE] / 2. The B values for other copolymers can be calculated analogously, by assigning the dyads of copolymer. For example, the calculation of the B value for a propylene / 1-ketene copolymer uses the following equation: B 2 • Fo »ft» For propylene polymers made with a metallocene catalyst, B values are typically between 0.8 and 0.95. In contrast, the B values of the propylene polymers made with a metallocene-free, metallocene, heteroaryl ligand catalyst (as described below), are above about 1.03, typically between about 1.04 and approximately 1 .08. In turn, this means that, for any propylene-ethylene copolymer made with said metallocene-free, metal-centered heterocaryl ligand catalyst, not only the length of the propylene block is relatively short, for a given percentage of ethylene, but There are very few, if any, long sequences of three or more sequential ethylene insertions present in the copolymer, unless the ethylene content of the polymer is very high. The data in the following table is illustrative. The data for table A below, were made in a solution circuit polymerization process, similar to that described in U.S. Patent No. 5,977,251, Kao and co-inventors, using a metal-centered heteroaryl ligand catalyst, without metallocene, activated, as described in its generality in U.S. Patent No. 6,960,635. It is interesting that the B values of the polymers of propylene made with the metallocene-centered heteroaryl ligand catalyst, remain elevated, even for polymers with relatively large amounts of ethylene, for example, more than 30 mole percent. 13C NMR Propylene-ethylene copolymers, suitable for use in this invention, typically have substantially isotactic propylene sequences. "Substantially isotactic propylene sequences" and other similar terms mean that the sequences have an isotactic triad (mm), measured by 3C RM N, of more than about 0.85, preferably, more than about 0.90; more preferably, more than about 0.92 and, most preferred, more than about 0.93. Isotactic triads are well known in the art and are described, for example, in U.S. Patent Nos. 5,504,172 and in WO 00/01 745, which refer to the isotactic sequence in terms of a triad unit in the molecular chain of the copolymer, determined by 13C NMR spectra. The 13 C NMR spectra are determined as follows: 13 C NMR spectroscopy is one of numerous techniques known in the art, which measure the incorporation of comonomer into a polymer. An example of this technique is described for the determination of the comonomer content for ethylene / alpha-olefin copolymers in Randall (Journal of Macromolecular Science, Reviews in Macromolecular Chemistry and Physics, C9 (2 and 3), 201 -31 7 (1989)). The basic procedure for determining the comonomer content of an olefin interpolymer involves obtaining the 3C RM N spectrum under conditions in which the intensity of the peaks corresponding to the different carbons present in the sample is directly proportional to the total number of contributing nuclei of the sample. Methods to ensure this proportionality are known in the art and involve the granting of sufficient time for relaxation after a pulse, the use of gate uncoupling techniques, relaxing agents, and the like. In practice, the relative intensity of a peak or a peak g from its computer-generated integral is obtained. After obtaining the spectrum and integrating the peaks, those peaks that are associated with the comonomer are assigned. This assignment can be effected by reference to known spectra or literature, or by means of the synthesis and analysis of model compounds, or by the use of an isotopically-labeled comonomer. The molar percentage of the comonomer can be determined by the proportion of the integrals corresponding to the number of moles of the comonomer, with respect to the integrals corresponding to the number of moles of all the monomers present in the interpolymer, as described, by example, in Randall. The data are collected using an NM N Varian U N ITY Plus 400 MHz spectrometer, which corresponds to a frequency of 13C resonance of 1 00.4 MHz. The acquisition parameters are selected to guarantee the acquisition of quantitative 1 3C data in the presence of the relaxant agent. The data are acquired using controlled decoupling with 1 H, 4000 transients per data file, pulse repetition delay of 7 secs, spectral amplitude of 24,200 Hz, and a file size of 32 K data points, with the head of probe heated to 1 30 ° C. The sample is prepared by adding about 3 mL of a 50/50 mixture of tetrachloroethane-d2 / orthodichlorobenzene, which has 0.025 M chromium acetylacetonate (relaxant) for a 0.4 g sample in a 10 mm N M RM tube. . The upper space of the tube is purged of oxygen by displacement with pure nitrogen. The sample is dissolved and homogenized by heating the tube and its contents at 150 ° C with periodic reflux, initiated by a heat gun. After the data collection, the internal reference of the chemical displacements to the pentameter is made mmmm to 21 .90 ppm. Isotacticity is determined at the triad (mm) level from the methyl integrals, which represent the mm triad (22.5 to 21.28 ppm), the mr triad (21.28-20.40 ppm) and the rr triad (20.67-1). 9.4 ppm). The percentage of tacticity mm is determined by dividing the intensity of the mm triad by the sum of the mm, mr and rr triads. For the propylene-ethylene copolymers, made with catalyst systems, such as the metal-centered, metallocene-free heteroaryl ligand catalyst (described above), the m r region is corrected. for ethylene and regio-error subtracting the contribution of PPQ and PPE. for propylene-ethylene copolymers, the rr region for ethylene and regio-error is corrected, subtracting the contribution of PQ E and EPE. For copolymers with other monomers that produce peaks in the regions of mm, n and rr, the integrals for those regions are corrected in a similar manner, subtracting the interfering peaks using common techniques and nuclear magnetic resonance currents, once They have identified the peaks. This can be achieved, for example, by analyzing a series of copolymers of various levels of monomer incorporation, by allocations of the literature, by isotopic labeling or by other means that are known in the art. For copolymers made using a metallocene-free, metal-centered heteroarilic ligand catalyst, such as described in US Patent No. 6,960,635, it is believed that the 13 C NM N peaks corresponding to a regio-error of approximately 14.6. and approximately 5.7 ppm, are the result of errors in the stereo-elective 2, 1 insertion of propylene units in the growing polymer chain. In general, for a given content of comonomer, the higher levels of regio-errors lead to a decrease in the melting point and the polymer modulus; while lower levels lead to a higher melting point and a larger modulus of the polymer. The matrix method to calculate the B values according to Koenig J. L. For the propylene / ethylene copolymers the following procedure can be used to determine the composition of the comonomer and the sequence distribution. The integral areas are determined from the 1 3 C NM N spectrum and entered into the matrix calculation to determine the mole fraction of each triad sequence. The then is used. matrix assignment with the integrals to produce the mole fraction of each triad. The matrix calculation is a linear implementation of the minimum squares of Randall's method (Journal of Macromolecular Chemistry and Physics, Reviews in Macromolecular Chemistry and Physics, C29 (2 and 3), 201 -31 7, 1 989), modified to include the peaks and the additional sequences for the regio-error in 2, 1. Table A shows the integral regions and triad designations used in the allocation matrix. The numbers associated with each carbon indicate in which region of the spectrum they will resonate. Mathematically, the matrix method is a vector equation s = fM, where M is an assignment matrix; s is a spectrum row vector, and f is a composition vector of the mole fraction. The successful implementation of the matrix method requires that M, fys be defined in such a way that the resulting equation is determined, or overdetermined (equations equal to or more independent than the variables), and the solution to the equation contains the molecular information needed to calculate the desired structural information. The first step in the method of matrix is to determine the elements of the composition vector f. The elements of this vector must be selected molecular parameters to provide structural information about the system that is being studied. For copolymers, a reasonable series of parameters would be any odd n-ad distribution. Normally the peaks obtained from the individual triads are reasonably well resolved, and are easy to assign; thus, the distribution of triads is the most frequently used in this composition vector f. The triads for the E / P copolymer are: EEE, EEP, PEE, PEP, PPP, PPE, EPP and EPE. For a polymer chain of reasonably high molecular weight (greater than or equal to 10,000 g / mol), the 13C RM N experiment can not distinguish EPP from PEE or PPE from EPP. Since all the Marcovian E / P copolymers have the molar fractions PEE and EPP equal to each other, the equality constraint for the implementation was also selected. The same treatment was carried out for PPE and EPP. The two previous equality constraints reduce the eight triads to six independent variables. For reasons of clarity, the composition vector f is still represented by the eight triads. The equality constraints are implemented as internal constraints, when the matrix is resolved. The second step in the matrix method is to define the spectral vector s. Usually the elements of this vector will be the well-defined integral regions in the spectrum. To ensure a given system, it is necessary that the number of integrals be as large as the number of independent variables. The third step is to determine the assignment shade M. The matrix is constructed by finding the contribution of the carbons of the central monomeric unit in each triad (column) to each integral region (row). It is necessary to be consistent about the direction of propagation of the polymer when deciding which carbons belong to the central unit. A useful property of this allocation matrix is that the sum of each row must equal the number of carbons in the central unit of the triad, which is the one that contributes to the row. This equality can be easily checked and, in this way, common errors in data entry are prevented. After building the assignment matrix, it is necessary to carry out a redundancy check. In other words, it is necessary that the number of linearly independent columns be greater than, or equal to, the number of independent variables present in the product vector. If the nuance does not pass the undancia network test, then it is necessary to return to the second step and the distribution of the integral regions, and then redefine the allocation matrix, until the reduction check is approved. In general, when the number of columns plus the number of additional restrictions or constraints is greater than the number of rows in the matrix M, the system is overdetermined. The greater this difference, the more overdetermined the system will be. The more the system is overdetermined, the more you can correct the matrix method, or the more you can identify the data inconsistent that could arise from the integration of data with low signal to noise ratio (S / N), or partial saturation of some resonances. The final step is to solve the matrix. This is easily executed in M icrosoft Excel, using the solve function. Solving works by first assuming a solution vector (molar proportions between different triads) and then iteratively assuming to minimize the sum of the differences between the calculated product vector and the product vector s entered. Solve also explicitly allows restrictions or constraints in an introduction. The contribution of each carbon on the central unit of each triad, to different integral regions, with P = propylene, E = ethylene and Q = propylene inserted in 2, 1, is reported in the following table: Guímico displacement ranges A B C D E F G H I 4 $ M 43.30 3S > , 00 37.25 35.80 35.00 34? 0 33.60 32. »45.60 43.40 37.30 3i.95 35.40 34.50 33.60 33.00 3250 3 KMNOPQ 31 JO 3G.20 2930 I? M 25.00 22.00 16.00 15.00 3030 29.80 28.20 27.10 24.50 19.50 15.00 14.00 The propylene composition inserted in 1, 2 is calculated by adding all the molar fractions of the triad sequence centered on the stereo-regular propylene; the composition (Q) of propylene inserted in 2, 1 is calculated by summing all the molar fractions of the triad sequence centered on Q. The molar percentage is calculated by multiplying the molar fraction by 1 00. The composition of C2 is determined by subtracting from 1 00 the values of molar percentage of P and Q. The asymmetry index is calculated from the data obtained from the fractionation with elution that raises the temperature (TREF). The data is expressed as a normalized graph of the weight fraction, as a function of the elution temperature. The separation mechanism is analogous to that of ethylene copolymers, so that the molar content of the crystallizable component (ethylene) is the primary factor that determines the elution temperature. In the case of propylene copolymers, the molar content of isotactic propylene units determines primarily the elution temperature.

The shape of the metallocene curve arises from the inherent random incorporation of the comonomer. A prominent feature of the shape of the curve is the drag at the lower elution temperature, as compared to the precision or predictedness of the curve at higher elution temperatures. A statistic that reflects this type of asymmetry is what is known as "asymmetry". Equation 1 mathematically represents the asymmetry index Smax as a measure of this asymmetry: Equation 1 The value Tmax is defined as the temperature of the maximum fraction of weight that elutes between 50 and 90 ° C in the TREF curve. Tj and wj are the elution temperature and the weight fraction, respectively, of an arbitrary fraction that occupies the "i" position in the TREF distribution. The distributions have been normalized (the sum of the ws is equal to 1 00 percent) with respect to the total area of the curve that elutes above 30 ° C. In that way, the index only reflects the shape of the crystallized polymer. Any uncrystallized polymer (the polymer that is still in solution at 30 ° C or below that temperature) has been omitted from the calculations shown in equation 1. Some of the copolymers of this invention are characterized by a DSC curve with a Tme that remains essentially the same, and a Tmax that decreases as increases the amount of unsaturated comonomer present in the copolymer. Tme means the temperature at which the fusion ends. max means the peak melting temperature. In one embodiment, the low crystallinity polymer additionally includes a non-conjugated diene monomer, to assist vulcanization and other chemical modification of the polymer blend composition. In a particular aspect of this embodiment, the amount of diene may be less than about 10 percent by weight (% by weight) or less than about 5 percent by weight. The diene may be any non-conjugated diene which is commonly used for the vulcanization of ethylene / propylene rubbers, including, but not limited to: ethylidene norbornene, vinylnorbornene or dicyclopentadiene. The low crystallinity polymer can be produced by any process that provides the desired properties of the polymer, in the heterogeneous polymerization on a support, such as a suspension or gas phase polymerization, or under homogeneous conditions in the bulk polymerization, in a medium comprising mainly monomer, or in solution with a solvent, as a diluent for the monomers. For industrial use, continuous polymerization processes are preferred. For homogeneous polymers, the polymerization process is preferably a one-stage, sustained-state polymerization carried out in a polymerization reactor with continuously mixed feed. Polymerization can be carried out in solution, although other polymerization processes are contemplated, such as gas phase or suspension polymerization, which satisfy the polymerization requirements in a single stage and in reactors with continuous feeding. The continuous polymerization n solution described in WO 02/34795 can make the polymers of low crystallinity, optionally in a single reactor and recovered by separation of the liquid phase of the alkane solvent. The low crystallinity polymers of the present invention can also be produced in the presence of a chiral metallocene catalyst, with an activator and an optional scavenger. The use of single site catalysts can be effected to increase the homogeneity of the low crystallinity polymer. Since only limited tacticity is needed, many different forms of the single-site catalyst can be used. Possible single-site catalysts are metallocenes, such as those described in U.S. Patent 5,026,798, having a single cyclopentadienyl ring, optionally substituted and / or forming part of a polycyclic structure, and a heteroatom, generally a n-atom. itrogen, but possibly also a phosphorus atom or a phenoxy group, connected to a transition metal of the group 4, such as titanium, zirconium or hafnium. Another example is MeSCpTiMe3, activated with B (CF) 3, which is used to produce elastomeric polypropylene, with an M n of up to 4 million. See Sassmannshausen, Bochmann, Rosch, Lilge, J. Organomet. Chem., (1 997), volume 548, pages 23-28. Other possible single-site catalysts are metallocenes which are bis-cyclopentadienyl derivatives, which have a transition metal of group 4, such as hafnium or zirconium. Said metallocenes may not have bridges, as in US patents 4,522, 982 or 5,747,621. The metallocene may be adapted to produce the low crystallinity polymer comprising predominantly propylene derived units, as in US Pat. No. 5,969,070, which uses a bis (2-phenyl-indenyl) zirconium dichloride without bridges, to produce a polymer. homogeneous that has a melting point of more than 79 ° C. The cyclopentadienyl rings may be substituted and / or form part of polycyclic systems, such as described in the patents cited above. Other possible metallocenes include those in which two cyclopentadienyls are connected by means of a bridge, generally a bridge of a single atom, such as a silicon or carbon atom, with a selection of groups to occupy the two remaining valences. Said metallocenes are described in U.S. Patent 6,048,950, which discloses bis (indenyl) bis (dimethylsilyl) zirconium dichloride and methyl aluminoxane (MAO); WO 98/271 54, which describes a bisindenyl-hafnium-dimethyl bridged dimethylsilyl, together with a non-coordinating anion activator; E P 1 070087, which describes a bridged biscyclopentadienyl catalyst, which has elements of asymmetry between the two ligands of cyclopentadienyl, to give a polymer with elastic properties, and the metallocenes described in U.S. Patents 6,448,358 and 6,265,212. In the mode using a single-site catalyst, the manner of activating the single-site catalyst may vary at convenience. Alumoxane, such as methyl alumoxane, can be used. Larger molecular weights can be obtained by using non-coordinating or slightly coordinating anion activators (NCA) derived and generated in any of the ways widely described in the art published in patents, such as EP 277 004, EP 426 637, and many others. In general, it is believed that activation involves the abstraction of an anionic group, such as the methyl group, to form a metallocene cation; although, according to a certain literature, hybrid ions can be produced. The NCA precursors may be a pair of ions of a borate or an aluminate, in which the precursor cation is removed by activation in some manner, for example, trityl or ammonium derivatives of tetrakis-pentafluorophenyl boron (see EP 277 004). The NCA precursor can be a neutral compound, such as a borane, which is formed into a cation by the abstraction of the anionic g rupe and the incorporation of the abstract group of the metallocene (see EP 426 638).

In a particular embodiment, the low crystallinity polymer is described in detail as the "second polymeric component (SPC)" in WO 08/69963, WO 00/01 766, WO 99/07788, WO 02/083753, and describes in more detail how "propylene-olefin copolymer" in WO 00/01 745. Infrared spectroscopy with Fourier transformation (FTI R) can measure the comonomer content of discrete molecular weight scales, together with the samples collected by G PC. U of such methods is described in Wheeler and Willis, Applied Spectroscopy (1 993), volume 47, pages 1 1 28-1 1 30. Different but similar methods are equally functional for this purpose, and are well known to those with experience. in the matter . The comonomer content and the sequence distribution of the polymers can be measured by 13C RM N. In some embodiments, the low crystallinity polymer is present in the article in a quantity ranging from a lower limit of about 5 percent or 1 0 percent or 20 percent or 30 percent or 60 percent or 70 percent or 75 percent, up to an upper limit of about 98 percent or 90 percent or 85 percent or 80 percent, by weight, based on the total weight of the item. The remainder of the article includes the high crystallinity polymer, optional additional polymer and various additives, as described hereinabove. Additional Polymers In some embodiments, the low crystallinity layer optionally comprises one or more additional polymers. The optional additional polymer can be the same high crystallinity polymer of the high crystallinity layer, or it can be different from him. In a particular embodiment, the additional polymer has a crystallinity that is between the crystallinity of the low crystallinity polymer and that of the high crystallinity polymer. In a particular embodiment, the low crystallinity layer is a mixture comprising a continuous phase including the polymer of low crystallinity described above, and a dispersed phase, which includes a relatively more crystalline additional polymer. Minor amounts of the additional polymer may be present in the continuous phase. In a particular aspect of the present embodiment, the dispersed phase is composed of individual domains less than 50 microns in diameter. In some embodiments, these individual domains of the dispersed phase can be maintained during processing, even without interlacing. In one embodiment, the additional polymer is a copolymer of ethylene with propylene, an alpha-olefin of 4 to 20 carbon atoms, or combinations thereof; wherein the amount of ethylene and / or alpha-olefin (s) of 4 to 20 carbon atoms present in the additional polymer is less than the amount of ethylene and / or alpha-olefin (s) of 4 to 20 carbon atoms present in the low crystallinity polymer. In a particular embodiment, the low crystallinity polymer and the additional polymer have polypropylene sequences with the same stereoregularity. In a non-restrictive example, the low-cristallity polymer and the additional polymer include isotactic polypropylene segments; in which more than 50 percent of the adjacent polypropylene segments are isotactic. In one embodiment the low crystallinity layer is a blend comprising from about 2 percent to about 95 percent by weight of an additional polymer, and from about 5 percent to about 98 percent by weight of the polymer of low crystallinity, with base on the total weight of the mixture; wherein the additional polymer is more crystalline than the low crystallinity polymer. In a particular aspect of this embodiment, the additional polymer is present in the mixture in an amount from a lower limit of about 2 percent or 5 percent, to an upper limit of about 30 percent or 20 percent or 1 5 per percent in weight, based on the total weight of the mixture. In another particular aspect of this embodiment, the additional polymer is isotactic polypropylene and has a melting point of more than about 10 ° C, and the low crystallinity polymer is a random copolymer produced by copolymerizing propylene and at least one of ethylene or an alpha-olefin having less than six carbon atoms, using a chiral metallocene catalyst system. In addition, in this embodiment, the low crystallinity polymer has a crystallinity from about 2 percent to about 50 percent of the isotactic polypropylene sequences; a propylene content of from about 75 percent to about 90 weight percent, and a melting point of about 25 ° C up to about 1 05 ° C. The mixture of the low crystallinity layer can be distinguished from the commonly obtainable reactor products, which frequently consist of a mixture of isotactic polypropylene and propylene and ethylene copolymers, having only a single phase, without prominent or continuous discontinuous phases. The mixture herein can also be distinguished from impact copolymers, thermoplastic olefins and thermoplastic elastomers produced by metallocene q-catalysts which, when combined with a second polymer, have a heterophasic morphology. Typically, in those materials, the most crystalline polymer is part of the continuous phase and not of the dispersed phase. The mixture herein can also be distinguished from other multi-phase mixture compositions in which it is not necessary to add a preformed compatibilizer., or formed in situ to reach and retain the morphology between the continuous phase of low crystallinity and the dispersed phase of high crystallinity. The high crystallinity layer The high crystallinity layer has a sufficient level of crystallinity to allow recoverable deformation and plastic deformation during elongation. The high crystallinity layer can be oriented in the direction of the machine, in cross direction to it, or in the oblique direction only, or in two or more of those directions, as can be detected by microscopy.

The orientation can lead to subsequent frangibility of the high crystallinity layer. The high crystallinity polymer The high crystallinity layer includes a high crystallinity polymer. The high crystallinity polymers of the present invention are defined as polymeric components, including mixtures, including homopolymers or copolymers of ethylene or propylene or an alpha-olefin having 1 2 carbon atoms or less, with minor amounts of olefinic monomers including olefins of 3 to 30 carbon atoms, linear, branched or ring-containing, capable of insertion polymerization, or combinations of these olefins. In one embodiment, the amount of alpha-olefin present in the copolymer has a scale of about 9 weight percent or 8 weight percent or 6 weight percent, and a lower scale of about 2 weight percent, based on the total weight of the high crystallinity polymer. Examples of minor olefinic monomers include, but are not limited to: linear or branched alpha-olefins of 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexen, 1-ketene, 4-methyl -1-pentene, 3-methyl-1-pentene and 3,5,5-trimethyl-1-hexen, and ring-containing olefinic monomers, containing up to 30 carbon atoms, such as cyclopentene, vinylcyclohexane, vinylcyclohexene, norbornene and methyl-norbornene. Suitable monomers containing aromatic group they may contain up to 30 carbon atoms and may comprise at least one aromatic structure such as a phenyl, indenyl, fluorenyl or naphthyl moiety. The monomer containing the aromatic group additionally includes at least one polymerizable double bond, such that, after polymerization, the pendant aromatic structure of the polymer backbone. The polymerizable olefinic portion of the monomer containing the aromatic group can be linear, branched, containing ring, or a mixture of those structures. When the polymerizable olefinic portion contains a cyclic structure, the cyclic structure and the aromatic structure may share 0, 1 or 2 carbons. The polymerizable olefinic portion and / or the aromatic group can also have from one to all hydrogen atoms substituted with linear or branched alkyl groups, containing from 1 to 4 carbon atoms. Examples of aromatic monomers include, but are not limited to: styrene, alpha-methylstyrene, vinyltoluenes, vinylnaphthalene, allylbenzene and indene; especially styrene and allylbenzene. In one embodiment, the high crystallinity polymer is a polypropylene homopolymer or copolymer with isotactic propylene sequences, or mixtures of such sequences. The polypropylene used can vary widely in its form. The propylene component can be a combination of homopolymeric polypropylene and / or random copolymers and / or block copolymers. In a particular embodiment, the elevated polymer Crystallinity is a copolymer of propylene and one or more comonomers, selected from ethylene and alpha-olefins of 4 to 12 carbon atoms. In a particular aspect of this embodiment, the comonomer is present in the copolymer in an amount of up to about 9 weight percent, or from about 2 weight percent to about 8 weight percent, or from about 2 weight percent to about 6 weight percent. percent by weight, based on the total weight of the copolymer. In another embodiment, the high crystallinity polymer is a homopolymer or a copolymer of ethylene and one or more comonomers selected from alpha-olefins of 3 to 20 carbon atoms. In a particular aspect of this embodiment, the comonomer is present in the copolymer in an amount of about 2 weight percent to about 25 weight percent, based on the total weight of the copolymer. In certain embodiments of the invention, the high crystallinity polymer has a weight average molecular weight (Mw) of from about 1,000,000 to 5,000,000 g / mol, or from about 20,000 to 1,000,000 g / mol, or from about 80,000 to 500,000 g / mol, and a molecular weight distribution Mw / M n (sometimes referred to as the "polydispersity index" (PDI)) ranging from a lower limit of about 1 5-1 .8 to an upper limit of about 40 or 20 or 1 0 or 5 or 3. In one embodiment, the polymer of high crystallinity is produced with metallocene catalysis and exhibits distribution narrow molecular weight; which means that the ratio of the weight average molecular weight to the number average molecular weight will be equal to, or less than, about 4; very typically, on the scale of about 1.7 to 4.0, preferably about 1.8 to 2.8. In another embodiment, the high crystallinity polymer is produced with a single-site catalyst (in the context of this embodiment, the term "single site" includes single-site catalysts without metallocene) and exhibits a narrow distribution of molecular weight, which means that the ratio of average molecular weight to number average molecular weight will be equal to, or less than, about 4; very typically, on the scale of 1.7-4.0, preferably from about 1.8 to 2.8. In another embodiment, the high crystallinity polymer is produced with a Zieg ler-Natta or chromium catalyst, and exhibits a medium to broad molecular weight distribution, which means that the ratio of average molecular weight to number average molecular weight will be equal to, or less than, about 60, more typically, on the scale of about 3.5 to 50; preferably, in the range of about 3.5 to 20. The high crystallinity polymers of the present invention may optionally contain long chain branches. These can be optionally generated using one or more a, tp-dienes. Alternatively, the high crystallinity polymer may contain small amounts of at least one diene, and preferably at least one of the dies is a non-conjugated diene to aid vulcanization or other chemical modification. The amount of diene preferably is not greater than about 10 percent by weight; more preferably, no greater than about 5 weight percent. Preferred dienes are those used for the vulcanization of ethylene / propylene rubbers, including, but not limited to: ethylidene norbornene, vinyl norbornene, dicyclopentadiene and 1,4-hexadiene. The embodiments of the invention include polymers of high crystallinity having a heat of fusion, when determined by DSC, with a lower limit of about 60 J / g or 80 J / g. In one embodiment, the high crystallinity polymer has a heat of fusion higher than the heat of fusion of the low crystallinity polymer. The embodiments of the invention include polymers of high crystallinity which have a melting point with a lower limit of about 1 00 ° C or 1 1 0 ° C or 1 1 5 ° C or 1 20 ° C or 1 30 ° C . In one embodiment, the high crystallinity polymer has a higher crystallinity than the low crystallinity polymer. The degree of crystallinity can be determined based on the heat of fusion of the polymer components. In one embodiment, the low crystallinity polymer has a lower melting point than the high crystallinity polymer; and the additional polymer, if used, has an intermediate melting point, between that of the low polymer crystallinity and that of the high crystallinity polymer. In another embodiment, the low crystallinity polymer has a lower heat of fusion than that of the high crystallinity polymer; and the additional polymer, if used, has an intermediate heat of fusion between the low crystallinity polymer and the high crystallinity polymer. The compatible crystallinity In some embodiments, the low crystallinity polymer and the high crystallinity polymer have compatible crystallinity. Compatible crystallinity can be obtained by using polymers for high crystallinity and low crystallinity layers, having the same type of crystallinity, or the same stereo-regular sequences, i.e., isotactic or syndiotactic. For example, compatible crystallinity can be obtained by providing both layers with methylene sequences of sufficient length, as achieved by the incorporation of units derived from ethylene. Compatible crystallinity can also be obtained by using polymers with stereo-regular alpha-olefin sequences. This can be obtained, for example, by providing syndiotactic sequences or isotactic sequences in both layers. In one embodiment, both the high crystallinity polymer and the low crystallinity polymer, including any mixed therein, contain polypropylene sequences which are substantially isotactic. In another embodiment, both the high crystallinity polymer and the low crystallinity polymer, including any mixed therein, contain polypropylene which are substantially syndiotactic. For the purposes of the present invention, "isotactic" refers to a polymer sequence in which more than 50 percent of the adjacent monomers, which have groups of atoms that are not part of the structure of the skeleton, are located totally above or totally below the atoms of the skeleton chain, when the latter is completely in a plane. For the purposes of the present invention, "syndiotactic" refers to a polymer sequence in which more than 50 percent of the adjacent monomers having groups of atoms that are not part of the skeleton structure are located u symmetrically above and below the atoms of the skeleton chain, when it is totally in a plane. Applications of the article The articles of the present invention can be used in a variety of applications. In one embodiment, the article is a film having at least two layers, which can be used in support sheets for diapers and similar absorbent garments, such as incontinence garments. In other embodiments, the article has the form of a cloth or a fiber. The fabric can be woven or non-woven. The fiber may be of any size or shape, and may be homogeneous or heterogeneous. If it is heterogeneous, it can be double component or double constituent.

The central layer or layers of the film of this invention comprise a propylene copolymer of low crystallinity. If the film of the present invention comprises two or more central layers, then the composition of each central layer may be the same or different with respect to the composition of the other central layer (s). The skin layers of the film of this invention comprise a high crystallinity, preferably non-tacky, homopolymer or polyolefin copolymer. "Not sticky" and other similar terms mean that it is not sticky to the touch. The composition of each skin layer may be equal to or different from the composition of the other skin layer (s). The particular combination of the core and skin layers is selected to ensure that the melting point of the core polymer is no greater than about 24 ° C more than the melting point of the skin polymer having the lowest melting point. Specific modalities Measuring methods Density method: Test samples were molded by compression (1 pu lgada x 1 inch x 0.125"= 2.54 cm x 2.54 cm x 3.1 7 mm) at 1 90 ° C in accordance with ASTM D4703-00 and cooled using procedure B. Once the sample was cooled to 40-50 ° C After the sample reached 23 ° C, its dry weight and weight were measured in isopropanol, using an Ohaus AP21 0 scale (Ohaus).

Corporation, Pine Brook N H, E. U. TO.) . Density was calculated as prescribed in ASTM D792, procedure B. DSC method: Differential scanning calorimetry (DSC) is a common technique that can be used to examine the fusion and crystallization of semi-crystalline polymers. The general principles of DSC measurements and DSC applications for studying semi-crystalline polymers are described in ordinary texts (for example, in EA Turi, ed., Thermal Characterization of Polymeric Materials, Academic Press, 1 981 ). Some of the copolymers used in the practice of the present invention are characterized by a DSC curve with a Tme that remains essentially the same and a Tmax that decreases as the amount of unsaturated comonomer present in the copolymer increases. Tme means the temperature at which the fusion ends. Tmax means the peak melting temperature. The analysis by differential scanning calorimetry (DSC) is determined using a DSC model Q 1 000 of TA I nstruments, I nc. The calibration of the DSC is carried out in the following manner. First a basic line is obtained operating the DSC from -90 ° C to 290 ° C, without any sample in the aluminum tray of the DSC. A sample of 7 milligrams of fresh indium is then analyzed, heating the sample to 1 80 ° C, cooling the sample to 140 ° C, at a cooling rate of 10 ° C / minute, followed by conservation of the sample isothermally at 140 ° C. "C during a minute, and then by heating the sample from 140 ° C to 1 80 ° C, at a heating rate of 1 0 ° C / minute. The heat of fusion and the beginning of the fusion of the indium sample is determined, and it is verified that it is within 0.5 ° C of 1 56.6 ° C for the beginning of the fusion, and within 0.5 J / g of 28.71 J / g for the heat of fusion. The deionized water is then analyzed, cooling a small drop of the fresh sample in the DSC tray, from 25 ° C to -30 ° C, at a cooling rate of 1 0 ° C / minute. The sample is isothermally maintained at -30 ° C for two minutes and heated to 30 ° C at a heating rate of 10 ° C / minute. The start of the melting is determined and checked to be within 0.5 ° C of 0 ° C. The samples are pressed to a thin film at a temperature of 1 90 ° C. 5 to 8 mg of the sample are weighed and placed in the DSC tray. A lid is curled on the tray to ensure a closed atmosphere. The tray with the sample is placed in the cell of the DSC and heated at a high speed of about 1 00 ° C / minute, to a temperature of about 60 ° C above the melting temperature. The sample is maintained at that temperature for about 3 minutes. The sample is then cooled at a rate of 1 0 ° C / minute to -40 ° C, and isothermally maintained at that temperature for 3 minutes. The sample is then heated at a rate of 1 0 ° C / min until the fusion is complete. The enthalpy curves are analyzed for the peak melting temperature, start and peak temperatures of crystallization, heat of fusion and heat of crystallization, Tme and any other DSC analysis of interest. The temperature is taken at the maximum rate of thermal fl ow within the melting scale, without reference to a baseline, such as the peak melting point. The mechanical test was carried out using an I nstron apparatus (model 5564) obtained from Itrontron Corporation (Norwood, MA, E. U. A). The copolymers used in the following examples of the invention and comparative are described in Table I. These copolymers follow the description of the preferred embodiments described above. These copolymers were produced according to U.S. Patent No. 6,960,635. Table I Resins The melt flow rate (MFR) and the melt index (M l), as used herein, were measured by ASTM D-1238 at 230 ° C and 1 90 ° C, respectively. Mixtures of low crystallinity polymer and high crystallinity polymer and other components can be prepared by any method that ensures intimate mixing of the components. For example, components can be combined by melting the components together in a Carver press at a thickness of approximately 0.5 millimeter (20 mils) and a temperature of approximately 1 80 ° C, in rolling the resulting plate, bending the ends to just them and repeating the pressing, rolling and bending operation approximately 1 0 times. Internal mixers are particularly useful for mixing in solution or in melting. Mixing at a temperature of about 1 80-240 ° C in a Brabender plastometer for about 1 to 20 minutes has been found satisfactory. Yet another method that can be used to mix the components involves mixing the polymers in an internal Banbury mixer, at a temperature above the flow temperature of all the components, for example, about 1 80 ° C for about five minutes. utos. A complete mixture of the polymeric components is indicated by the uniformity of the morphology of the low crystallinity polymer dispersion and the high crystallinity polymer. Continuous mixing can also be used. These processes are well known in the art and include mixer extruders of a single screw and double screw; static mixers for mixing molten polymer streams, low viscosity; impact mixers, as well as other machines and processes designed to disperse the low crystallinity polymer and the high crystallinity polymer, in intimate contact. Those with experience in the field will be able to determine the appropriate procedure for mixing the polymers to balance the need to intimately mix the component components with the desire for economy in the process. The components of the mixture are selected based on the desired morphology for a given application. The high crystallinity polymer can be co-continuous with the low crystallinity polymer in the film formed from the mixture; however, a polymer phase of high crystallinity, dispersed, is preferred in a continuous phase of low crystallinity polymer. Who have experience in the matter can select the volumetric fractions of the two components to produce a dispersed morphology of polymer of high crystallinity in a continuous matrix of polymer of low crystallinity, based on the proportion of viscosity of the components (see S. Wu, Polymer Engineering and Science, volume 27, page 335, 1987). The three-layer blown film line used to prepare the examples of the invention and the comparative examples is described as follows. There are three extruders [a 60-horsepower extruder, equipped with a high-effort screw Cutter, with a diameter of 2.5 inches (6.35 cm) (Davis-Standard Film &Coating Systems, Somerville, NJ, USA), a 75-horsepower extruder, equipped with a 2.5-inch (6.35 cm) screw ( Davis-Standard Film &Coating Systems) and a Joh nson 20-horsepower extruder, equipped with a one-step screw, with a diameter of 2 inches (5.08 cm)] that feed a multilayer die, 6 inches in diameter (15.24 cm) (Macro Engineering and Technology I nc., Mississauga, Ontario, Canada). For the examples of the invention and the comparative examples, a die separation of 70 mils (1778 mm) was used. The height of the frozen line was 24 to 30 inches (60.96-76.2 cm). The examples of the invention and the comparative examples were extruded according to the conditions described in Table I I. Col and Co2 are the comparative films. Ex1 and Ex2 are the films of the invention. Table II Blowing conditions of the film The test specimens with the required geometry were removed from the films, after at least seven days from the manufacture of the film, and were evaluated in an Instron 5564, equipped with Merlin software, obtainable from Instron Corporation (in Canton, MA, USA), to produce the data of mechanical deformation. The Instron 5564 and associated equipment can be obtained from The Instron Corporation. All data are reported in terms of engineering stress and strain, with uncorrected stress values for the contraction in the cross section of the sample being tested. Pre-stretching Micro-tensile samples were taken (ASTM D-708) using a die oriented in the machine direction of the film. The caliber length was taken as 22.25 mm. The samples were subjected to a pre-stretching step by loading the samples in the Instron and pulling them at 0 (control) or 100 or 300 or 500 percent effort at a rate of 500 percent / min u (1 1 1. 25 mm / minute) and then immediately returning to 0 percent effort at the same speed. The new gauge length was measured after waiting at least 10 minutes after the pre-stretch step. Hysteresis tests at 50. 100, 1 50 percent The pre-stretched samples were then re-stretched (first stretch step) at 0 or 50 or 1 00 or 1 50 percent stress in relation to the new length of gauge of the sample pre-stretched at 500 percent / minute, and then immediately returning to 0% effort at the same speed. The new sample was immediately extended to 500 percent / minute until the start of the positive tensile force. The effort corresponding to the beginning of the positive force was taken as the deformation effort. At least three samples were measured for each pre-stretched condition, and the one corresponding to the first stretched condition. The average deformation effort and the average norm and the corresponding deviation from the norm are reported in table III. Table III - Examples Example * A? TA Capa Capa Capa lmJl ¡w? Pre-stretch- (1) (2) (3) ft »« lie (1) = First stretch (2) Average deformation (3) Deviation from the norm * Ex denotes an example of the invention. Co denotes a comparative example (compression molded at 1 90 ° C). Ref denotes reference not previously stretched. Figure 1 shows the immediate deformation behavior for the hysteresis test at 50 percent of the examples of the invention and comparatives that have undergone pre-stretching from 0 percent (comparative control) to 1 00 percent, up to 300 percent cent, up to 500 percent effort. The data show that the immediate deformation behavior can be significantly improved by pre-stretching. A significant improvement is also shown for hysteresis behavior at 1 00 percent and 1 50 percent (Figures 2 and 3, respectively). The resulting, immediate deformation behavior of the pre-stretched examples of the invention is shown to be comparable with, or better than, SBC or polyethylene-based resins. SBC is an SEBS obtainable from Kraton Polymers (Houston, TX, E. U. A.). While illustrative embodiments of the invention have been described in detail, various other modifications will be apparent, and can be easily realized by those with experience in the art, without departing from the spirit or scope of the invention. Accordingly, the scope of the following claims is not limited to the examples or to the descriptions Rather, the claims should be considered covering all aspects of the patentable novelty that reside in the present invention, including all aspects that would be treated as equivalents of those aspects, by those who are experts in the art to which the invention belongs. When the lower numerical limits and the upper numerical limits are listed above, the scales are contemplated from any lower limit to any upper limit. All issued US patents and all US patent applications granted, cited above, are incorporated herein by reference.

Claims (52)

1. REIVI N DICACIONES 1 . An article that has at least two layers; the article comprising: (a) a low crystallinity layer, which comprises a low crystallinity polymer having a melting point; and (b) a high crystallinity layer comprising a polymer of high crystallinity having a melting point, when determined by DSC, which is approximately equal to, or which is within less than 25 ° C of, the melting of the low crystallinity polymer; the article being elongated below the melting point of the low crystallinity polymer, in at least one direction, to an elongation of at least 50 percent of its original length or width.
2. 2. An article that has at least two layers; the article comprising: (a) a low crystallinity layer comprising a polymer of low crystallinity having a melting point; and (b) a high crystallinity layer comprising a polymer of high crystallinity with a melting point, as determined by DSC, which is less than that of the low crystallinity polymer; the article being elongated below the melting point of the low crystallinity polymer, at least in one direction, to an elongation of at least 50 percent of its original length or width. 3. The article according to claim 1, wherein the low crystallinity polymer and the high polymer crystallinity have a percent difference in weight of crystallinity of at least about 1 percent. 4. The article according to claim 1, wherein the low crystallinity polymer and the high crystallinity polymer have compatible crystallinity. The article according to claim 1, wherein the high crystallinity polymer is present in the article at a level of less than about 20 weight percent, based on the combined weight of the high and low polymers. low crystallinity 6. The article according to claim 1, wherein the high crystallinity polymer is present in the article at a level of less than about 10 weight percent, based on the combined weight of the polymers of high and low crystallinity 7. The article according to claim 1, wherein the low crystallinity polymer is present in the article at a level of at least about 45 percent, based on the combined weight of the polymers of high and low crystallinity 8. The article according to claim 1, wherein one of the layers comprises a nonwoven, and wherein the nonwoven comprises the high crystallinity polymer. 9. The article according to claim 1, wherein one of the layers comprises a film, and wherein the layer of The film comprises the high crystallinity polymer. 1. The article according to claim 1, wherein each layer comprises a film. eleven . The article according to claim 1, wherein one of the layers comprises a film, and wherein the film layer comprises the low crystallinity polymer. 12. The article according to claim 1, wherein the low crystallinity layer additionally comprises an additional polymer.
3. 3. The article according to claim 1, wherein the additional polymer has a higher crystallinity than that of the low crystallinity polymer. 14. The article according to claim 1, wherein the additional polymer is present in an amount of about 2 weight percent to about 30 weight percent, based on the weight of the low crystalline layer. idad. The article according to claim 1, wherein the low crystallinity polymer is a copolymer of propylene and one or more comonomers, selected from ethylene and alpha-olefins of 4 to 20 carbon atoms, and in which The units derived from the comonomer or the comonomers are present in the low crystallinity polymer in an amount of about 2 weight percent to about 25 weight percent, based on the weight of the low crystallinity polymer. The article according to claim 1, wherein the low crystallinity propylene copolymer has an M FR, when measured by ASTM D-1 238, condition L, from about 0.2 to about 90 g / 1. 0 minutes 7. The article according to claim 16, wherein the low crystallinity polymer has a heat of fusion, when determined by DSC, from about 3 J / g to about 50 J / g, and a weight distribution. molecular weight from about 2 to about 4.5. The article according to claim 17, wherein the high crystallinity polymer is a homopolymer or a copolymer of propylene and one or more comonomers selected from ethylene and alpha-olefins from 4 to 20 carbon atoms. 9. The article according to claim 17, wherein the high crystallinity polymer is a homopolymer or a copolymer of ethylene and one or more comonomers selected from ethylene and alpha-olefins of from 3 to 20 carbon atoms. 20. The article according to claim 1 9, wherein the low crystallinity layer is in contact with the high crystallinity layer. twenty-one . The article according to claim 1, wherein the article comprises a film, and the film comprises an additional layer, in contact with the layer of high crystallinity. 22. The article according to claim 1, wherein the article comprises a film and the film comprises a additional layer, in contact with the low crystallinity layer. 23. The article according to claim 22, wherein the additional layer is more crystalline than the low crystallinity layer. 24. The article according to claim 1, wherein the high crystallinity layer is plastically deformed. 25. The article according to claim 1, wherein both layers are elongated by at least about 50 percent. 26. The article according to claim 1, wherein the high crystallinity layer is a non-woven layer. 27. The article according to claim 1, wherein the low crystallinity layer is a non-woven layer. 28. The article according to claim 24, comprising a film, and the film has a haze value of more than about 70 percent. 29. The film according to claim 28, having a permanent deformation of less than about 30 percent, after a 50 percent hysteresis test. 30. The film according to claim 28, which comprises three or more layers. 31 A portion of garment comprising the article of claim 28, adhered to a substrate of the garment. The article according to claim 1, wherein at least one additional layer comprises at least one of between a load and an additive. 33. The article according to claim 32, wherein the additive is at least one of: calcium carbonate, talc, titanium dioxide, carbon black, diatomaceous earth and an antiblock, a lubricating additive and an antioxidant. . 34. A process for forming the article of claim 1 in the form of a film; comprising the process: (1) forming the film and (2) lengthening the film. 35. The process according to claim 34, wherein the elongation step comprises elongating the film in at least one direction, at an elongation of at least about 50 percent of its original length or width. 36. The process according to claim 35, wherein the elongation step comprises elongating the film at least in one direction to obtain a turbidity value of at least about 10 percent. 37. The article according to claim 1, in the form of a fiber. 38. The fiber according to claim 37, in the form of a double component fiber, wherein the high crystallinity polymer comprises at least a portion of the surface of the fiber. 39. The fiber according to claim 38, in the form of a double component fiber, wherein the low crystallinity polymer comprises at least a portion of the surface of the fiber. 40. The fiber according to claim 38, having a configuration selected from the group consisting of sheath / core, side by side, crescent, trilobal, islands at sea, and flat. 41 The fiber according to claim 39, having a configuration selected from the group consisting of sheath / core, side by side, half moon, trilobal, islands at sea and flat. 42. The fiber according to claim 37, wherein the high crystallinity polymer has been plastically deformed. 43. A web comprising the fiber of claim 37. The web according to claim 43, wherein at least a portion of the fibers are bonded together. 45. The process according to claim 36, wherein the elongation step is effected below the melting point of the high crystallinity polymer. 46. The process according to claim 36, wherein the elongation step is effected below the melting point of the low crystallinity polymer. 47. The fiber according to claim 42, wherein the high crystallinity polymer further comprises succinic acid functionality or succinic anhydride functionality. 48. The fiber according to claim 42, in the that the high crystallinity layer comprises at least one polyolefin catalyzed by Ziegler-Nata, metallocene or single-site catalyst; and the low crystallinity layer comprises a propylene-based polymer. 49. The article according to claim 1, in the form of a multilayer article comprising at least one skin layer and at least one core layer, wherein at least one core layer comprises the polymer. of low crystallinity. 50. The article according to claim 1, in the form of a multilayer article, comprising at least one layer of skin and at least one central layer, wherein at least one layer of skin comprises the high crystallinity polymer. 51 The article according to claim 1, in the form of an interlaced film. 52. The article according to claim 1, wherein at least one layer does not have a different melting point. SUMMARY In one embodiment, the invention is an article comprising at least two layers: a first layer or layer of low crystallinity, comprising a polymer of low crystallinity, and a second layer or layer of high crystallinity, comprising a high polymer. crystallinity. The high crystallinity polymer has a melting point, when determined by differential scanning calorimetry (DSC), which is approximately equal to the melting point of the low crystallinity polymer, or is within less than 25 ° C of that point. The article is elongated at a temperature below the melting point of the low crystallinity polymer, at least in one direction, at an elongation of at least about 50 percent of its original length or width, to form a pre-coated article. -stretched. Preferably the high crystallinity layer is capable of undergoing plastic deformation with elongation.