MXPA00003541A - Anisotropic elastic films and webs - Google Patents

Abstract

An anisotropic elastic web, particularly an anisotropic elastic film layer having a machine direction and a cross direction and having a thickness of from 20 to 300 microns formed of an extruded blend of a block copolymer elastomer portion and a polyolefin polymer portion blended in a ratio of from 10:1 to 0.4:1, respectively. The elastomer portion generally is a block copolymer elastomer formed of A blocks and B blocks, the A blocks are formed predominately of monoalkenyl arene and the B blocks are formed predominately of conjugated diene. The polyolefin portion is comprised predominately of an inelastic fiber forming polyolefin polymer, copolymer or blend. The anisotropic film layer has a F10 force Ratio (MD to CD) of at least 1.5. This anisotropic elastic web is usable in a variety of garment applications where an elastic is supplied in roll form and requires strength in a machine direction and elastic properties in a cross direction.

Description

ENTRAMADOS AND ELASTIC ANISOTROPIC FILMS Background and Field of the Invention The invention concerns elastic film materials and laminated products containing elastic film materials.

Elastic film materials, non-woven materials and other lattice-like materials are used with increasing frequency in the area of personal or disposable clothing products, by garment refers to a product that is used in, or in association with, a body (human or animal). Specifically, such uses include disposable diapers, exercise pants, incontinence articles, sanitary napkins, bandages, curtains and surgical gowns, non-interspersed medical materials, masks, sports bandages and the like. Generally, these elastomeric materials are formed with conventional elastomers that generally exhibit elastic properties in substantially all directions, particularly if it is in the form of a REF .: 119358 elastic film. However, for some specific applications, it is desired to have materials that are primarily elastic only in one direction, ie, anisotropically elastic materials. A large number of patent applications have been directed towards this problem, providing a wide variety of solutions. The most common approach in the art is to laminate an elastic material in a second web material that is easily stretched in one direction but not in the transverse direction. PCT Application No. 96/10481 discusses this version of this approach stating that a common practice is to produce the so-called "elastic-bonded laminate product". In these elastic-bonded laminated products, an elastic film or non-stretched material, or similar elastic material, elongates in one direction only. While elongated, the elastic lattice either joins continuously or in point with inelastic web material. Then, the tension is released and the elastic lattice is allowed to recover in the opposite direction to its elongation. Then the fixed non-elastic web material is gathered causing the elastic-bonded laminate to be easily stretchable in the direction of elongation of the elastic web but not in the transverse direction. The rolled product can then be re-stretched to the point of pre-elongation of the elastic framework. However, it is indicated that this puckering is undesirable for some applications. In order to overcome the problem of shirring, the application WO 96/10481 proposes to use an inelastic non-woven mesh material with a large number of substantially parallel cuts. Then this non-woven and cut mesh material is attached to an unstretched elastic mesh material. When the rolled product is stretched in a direction perpendicular to the direction of the cuts the rolled product is stretched and recovered without the formation of wrinkles or collected in the non-woven inelastic mesh.

Some patent documents that discuss or address the prior art methods described in the above PCT application include European Patent Application No. 693585 A2 and Patents of E. U. A. Nos. 4, 413, 623; 4, 606, 964 and 4, 720, 515 all of which stretch an elastic mesh material and then bind it to the stitches, or otherwise bind the stretched elastic mesh to a relatively inelastic mesh material, and this inelastic mesh material Subsequently, it is collected when it is allowed to recover the tension elastic mesh. In a variant of this, U.S. Patent No. 4, 525, 407 together with elastic and inelastic mesh materials while the elastic mesh is not tensioned. The rolled product is stitched together and then stretched under a tension strong enough to cause the inelastic mesh material to deform permanently. Whose deformed inelastic material is then gathered or gathered at the time of recovery of the elastic material. It reveals a method similar to this in, for example, the numbers of U.S. Patents 5,527,304 and 5, 167, 897. The materials formed in these patents have been called "zero stress" elastic materials in which the inelastic and elastic mesh materials come together either without being under tension. The one or more inelastic mesh materials and the elastic mesh materials are then subjected to particular forms of increased tension between the corrugated rolls in mesh. Other materials collected in a dailizing manner can also be produced using heat shrinkable elastic materials such as those disclosed in U.S. Patent Nos. 3, 819, 404 and 3, 912, 565.

It also reveals a non-woven corrugated non-woven between interlocking teeth or corrugated rolls. While the inelastic web is corrugated, it is attached to an elastic web material by extrusion lamination or adhesive lamination as disclosed, respectively, in PCT Application No. WO 95/34264 and Japanese Kokai No. HEI 7-213554. These laminated materials have relatively large, and uniform gathers compared to other methods described above. These materials also have uniform elastomeric properties and are aesthetically pleasing. However, these elastic rolled products are generally very thick and as such may not be suitable for certain types of applications that require a flatter profile elastic material.

Elastic anisotropic materials having elasticity in the cross-linked direction are disclosed, for example, in US Pat. Nos. 5, 514, 470; 4, 965, 122; 5, 226, 992; 4, 981, 747 and European Patent No. 707106. In these patents, a "shrinkable" non-woven non-woven web material is used. Suitable nonwoven shrinkable frameworks include carded webs glued by rotation or blown. Non-woven shrinkable webs are stretched in the grain direction in a way that causes the inelastic webs to narrow (i.e., decrease in width) in the cross direction. While the non-woven webs are narrowed in this way, they are joined to an elastic web such as a film or non-woven material, either continuously or in the form of a point connection. The resulting laminate is generally inelastic in the direction of the grain while being substantially elastic in the cross direction to the width of the cross dimension of the original of the reversibly constricted material.

A non-woven inelastic web material exhibiting elastic-like properties is disclosed in US Patent No. 3,949, 128. In this patent, a continuous filament non-woven web, as produced by a spin bonding process, is unites by point and then either stretches in the grain direction or is microreliefed in the direction of the grain and then subjected to thermal fixation. Depending on whether the thermally fixed web material is stretched or microreliefed, it exhibits a similar elastic property to the CD or an elastic property similar to the MD, respectively.

U.S. Patent No. 5, 366, 793 discloses an anisotropic elastomeric non woven fibrous web of blown elastomeric fibers. The anisotropic behavior is obtained by aligning the fibers with a current of air to produce a lattice with a greater tension of maximum weight in the direction of the orientation of the fibers.

In the Patents of E. U. A. Nos. 5, 344, 691; 5, 501, 679 and 5, 354, 597 include multilayer elastomeric films that include shells having an elastomeric centered layer and one or two layers of outer film of a relatively inelastic material. The multi-layer films are co-extruded to produce thin layers of inelastic film and a reluctantly thick elastic pallet layer. These co-extruded film materials are called elastic stretch-activated materials (SAE) and are substantially inelastic when formed but when stretched in one direction and allowed to recover exhibit uniaxial elastic properties in the direction in which the rolled product has been stretched and recovered. Materials that have been stretched uniaxially exhibit substantially anisotropic elastic behavior. The anisotropic elastic behavior in these co-extruded laminated products can be set as described in US Patent No. 5, 462, 708 by subjecting a uniaxially stretched laminate to a deactivating heat treatment., while in the stretched condition. The heat treatment is such that the elastic force of recovery of the elastic material is allowed to dissipate without substantially affecting the orientation of the elastic coating materials. The thermally treated laminate is then stretched in a second crossed direction and allowed to recover as described above. The resulting material is extremely strong in the direction of the original and elastic elasticity in the cross direction. Generally, these SAE materials are extremely advantageous where a low elastic profile type framework is required, wherein the elasticity may have either isotropic or elastic anisotropic properties as may be required.

A single layer film elastic material is disclosed in Japanese Patent Kokai No. 5-186611, this patent discloses the extrusion of a combination of a block ABA copolymer with polystyrene wherein the polymers are exemplified by being combined in a ratio of 50 to 99% block copolymer of 1 to 50% polystyrene. The resulting material that is produced exhibits anisotropic elastic behavior. Polypropylene is exemplified by not functioning to produce anisotropic behavior. Materials of the type disclosed in this Kokai have been found to have a relatively low tear resistance and unless properly treated with an antiblocking agent or the like tend to exhibit a highly blocking behavior.

There is a continuing need for other forms of anisotropic elastic frameworks suitable for use in a wide variety of potential applications where the framework materials are easy to manufacture, from easily rolling up and subsequently unrolling easily without blocking, to handle and become their final form for use in a limited-use garment and the like.

Brief Description of the Invention Anisotropic elastic web material comprising an anisotropic film layer containing a grain direction and a cross direction and having a thickness from about 20 to 300 microns is formed from an extruded combination of a portion of a block copolymer elastomer and a portion of a polyolefin polymer combined in a ratio of from about 10: 1 to 0.4: 1, respectively. The elastomer portion comprises a block copolymer elastomer formed from blocks A and blocks B, blocks A are formed predominantly from monoalkenyl sand and blocks B are predominantly formed from conjugated diene and the polyolefin portion comprises predominantly an inelastic polyolefin polymer , copolymer or a mixture. The anisotropic film layer has a ratio of FIO (MD to CD) of at least 1.5, preferably greater than ^ 2.0. this elastic anisotropic film can be integrated into a roll of film that can be unwound without blocking.

In a second embodiment, the anisotropic elastic film may comprise a multilayer film of this anisotropic elastic film layer and at least one other layer of polymer film. The other film layer is generally a relatively inelastic film layer compared to this elastic film layer and these film layers are co-extruded.

Generally, the anisotropic elastic web has an average tear strength of at least 20 g / 25 μ and the permanent array of the anisotropic elastic film layer in the CD direction is less than about 80% when the film layer is stretched 200% Generally the film is not stressed but can be stressed in the grain direction for additional anisotropic properties.

Description of the Preferred Modalities The present invention relates generally to non-blocking anisotropic thin elastic films and elastic laminates using these films. Anisotropic elastic films are characterized by having a grain direction and a substantially perpendicular cross direction. The elastic properties of the film are substantially anisotropic in that the films are substantially less elastic in grain direction relative to the cross direction, i.e. the film as it is formed is substantially more elastic in the cross direction than in the cross direction. grain direction, as defined here. Generally, in the cross direction, the film of the invention, as it is formed, when initially stretched by approximately 200% is recovered and holds a permanent fix at the time of relaxation and is generally less than 80% and preferably less than 50% of the original length of the elastic film or the laminated product of the film. Although the direction of the grain may exhibit elastomeric properties, the force required for the increased elongation in the grain direction is substantially greater than in the cross direction, at least at low elongation levels of less than 5 to 10%.

The anisotropic elastic film of the invention is formed by extruding the film material from a combination of a portion of block copolymer elastomers with an olefinic portion of relatively inelastic polymer material. The anisotropic film of the invention generally demonstrates improved tear strength relative to single layer anisotropic elastic films as discussed in Japanese Patent Application Kokai No. 5-186611. However, this improved tear strength can be obtained without substantially reducing the anisotropic elastic properties of the film or significant reductions in the overall elasticity of the film of the invention.

The block copolymer elastomers in the elastomer portion are generally formed of blocks A and B wherein the block A is formed predominantly of monoalkenyl halides, preferably of styrenic and more preferably styrene moieties, having a molecular weight distribution of block of between 4,000 and 50,000. The B blocks are predominantly formed from conjugated dienes, and have an average molecular weight of between about 5,000 to 500,000, these B-block monomers can then be hydrogenated or functionalized. Blocks A and B are conventionally configured in linear, radial or stellar configuration, among others, wherein the block copolymer contains at least one block A and one block B, but preferably contains multiple blocks A and / or blocks B, whose blocks can be the same or different. A preferred block copolymer of this type is a linear ABA block copolymer wherein the A blocks can be the same or different. Other copolymers are also preferred in multiple blocks (block copolymers having more than 3 blocks) and predominantly terminal blocks A. These preferred multi-block copolymers may also contain a certain proportion of the dual block copolymer AB. However, the amount of double AB block copolymers is generally limited as it tends to form a more sticky elastomeric film which has an increased tendency to block, unless it is in its laminated form. Generally the amount of dual blocks is less than 50%, preferably less than 20% of the elastomer portion of the anisotropic elastic film. To a certain degree, minor proportions of other elastomers can be combined with the block copolymer elastomer provided that they do not unfavorably affect the anisotropic elastomeric properties of the elastic film material as defined above. Apart from polystyrene, blocks A can be formed of alphamethyl styrene, t-butyl, styrene and other predominantly alkylated styrene, as well as mixtures and copolymers thereof. Block B can be formed preferably from isoprene, 1,3-butadiene or ethylene-butylene monomers, however, isoprene is preferred.

The portion of the inelastic polymer material combined with the elastomer portion of the block copolymer is generally predominantly a fiber-forming polyolefin, the exemplary polyolefins include polypropylene, polyethylene, ethylene-propylene copolymers, impact copolymers, polypropylene copolymers, butene polymers and copolymers and combinations thereof. The ratio of the portion of the elastomer to the portion of the inelastic polyolefin polymer is generally from 10: 1 to 0.4: 1, preferably from 5: 1 to 0.6: 1. A smaller portion of the inelastic polymer portion of the combination of the invention includes non-olefinic materials, generally from zero to 20%, preferably from 0 to 10% of the inelastic polymer portion provided that additional monoolefinic materials are substantially incompatible with the block copolymer portion they are preferably similar in their fiber formation or compatible with the copolymer of the material portion of the inelastic polymer.

The general thickness of the anisotropic elastic film formed is generally from 20 to 300μ, preferably from 25 to 100μ. If the thickness of the elastic material is greater than 300 μ the material is too difficult to elongate in the cross direction making it unsuitable for use in garments and the like for which the film material of the invention is designated. If the thickness of the film is less than 20μ, generally the elastic force provided by the films of the invention is insufficient. Generally the force required to stretch the film in the cross direction of greater elasticity by 10%, as defined in the examples, is less than about 60 kg / cm2, preferably less than 40 kg / cm2, and greater preference less than 20 kg / cm2. In addition, the proportion (FIO ratio) of this force of 10% in the grain direction (MD) to the cross direction (CD) is generally greater than 1.5, preferably greater than 2.0 and more preferably greater than 2.5. this proportion of the FIO force is a quantification of the anisotropic elastic behavior of the film of the invention.

Films of the invention may exhibit improved tear resistance when compared to films that are formed only from the elastomer portion. This is really less than an improvement of 50%, preferably an improvement of 100%, with a range of up to 10 times more improvement or depending more on the materials and their relative proportions. Usually. This improvement is noted after the ratio of the portion of the elastomer to the polymer portion is greater than 3 down to approximately 2. The tear resistance as defined in the examples is preferably at least 20-25 μ and more preferably at least 30-25 μ. The non-blocking behavior is generally noted when the ratio of the portion of the elastomer to the polymer portion is less than about 2.5: 1.

Generally, the anisotropic film of the invention can be integrated into a roll for subsequent use without substantial blocking or stretching of the elastic film in the grain direction when it is unwound from the roll. The blocking in this invention refers to the relative tendency of the laminated film or product to adhere to itself when in the form of a roll. If this self-adhesion is very high, the film either does not unroll or unwind with great difficulty and possibly the film is damaged. Generally, the unwinding force for a roll of the elastic film material should be 300 g / 2.54cm or less, preferably 200g / 2.54cm, or less in average strength in any event less than the FIO force in the direction of the grain. Although not generally needed, A, or coated in anti-blocking agents or releasing agent modifiers may be added to the film of the invention or laminate of the invention if desired, suitable anti-blocking products include particulate additives such as calcium carbonate and the like. The releasing agents include materials such as silicones, fluoropolymers, stearates. Other conventional additives such as dyes, pigments, antioxidants, antistatic agents, adhesion aids, thermal stabilizers, photostabilizers, foaming agents, glass bubbles and the like can be used when required in any portion of the incompatible combination.

The anisotropic film material of the invention may also be the elastic layer in a multilayer film structure as disclosed in U.S. Patent Nos. 5, 501, 675; 5, 462, 708; 5, 354, 597 or 5, 344, 691 whose substances are substantially incorporated herein by reference. These references teach various forms of elastic laminated products co-extruded in multiple layers, at least with an elastic central layer and towards one or two relatively inelastic coating layers. The coating layers can be stretched beyond an elastic limit of these layers (ie, are permanently deformed) and the coextruded rolled product is subsequently recovered in the direction opposite to the direction of the stretch by the relatively higher elastic recovery of the central elastic layer. The result of the formation of a material that is selectively elastic only in those directions in which it stretches and recovers.

The coating layers recover little or at least less from the elastic center and are selected so that they form a microtexture or microstructure. The microtexture or microstructure means that the coating layer contains crest and valley irregularities or folds that are large enough to be perceived by the human eye without help as they cause an increased opacity on the opacity of a rolled product before stretching and recovering. The irregularities are small enough to be perceived as smooth or soft on human skin and magnification is required to see the details of microtexturing.

The coating layers are generally in the form of any semicrystalline or amorphous polymer that is less elastomeric than the elastic core layer and which experiences relatively greater permanent deformation than the core layer in the percentage by which the elastic laminate is stretched. Slightly elastomeric materials such as olefinic elastomers, for example, ethylene-propylene elastomers, ethylene propylene diene polymer elastomers, metallocene polyolefin elastomers or ethylene vinyl ethylene elastomers may be used as long as the coating layers provided are substantially less elastomeric than the elastic center layer. Preferably, these coating layers are polyolefinically formed of predominantly polymers such as polyethylene, polypropylene, polybutylene, and polyethylene-polypropylene copolymer, however, these coating layers may also be partially or entirely of polyamide, such as nylon, polyester, such as polyethylene peraphatalate, or the like, and suitable combinations thereof. Generally, the material of the coating layer after stretch and elastic recovery is in contact with the elastic material of the core layer in at least one of three suitable ways; first, continuous contact between the elastic central layer and the microtexturized coating layer, second, the continuous contact between the layers with cohesive failure of the core layer material under the folds of the microtexturized coating and third, adhesive failure of the coating layer to the central layer under the microtextured folds with the intermittent contact of the coating layer towards the central layer in the valleys of microtextured folds. Generally, in the context of the present invention, all 3 coating-to-center contact forms are acceptable. However, preferably the coating and core layers are in substantially continuous contact to minimize the possibility of delamination of the coating layers of the elastic core layer.

Generally, the ratio of the thickness of the core layer to the coating layer is at least 3. preferably at least 5, but less than 100, and more preferably from 5 to 75. Generally, the general caliper of the multilayer film is as described above for the anisotropic elastic film material.

The addition of the coating layer materials, as described in the above references, generally tends to further strengthen the material layer of the anisotropic elastic film in the grain direction. Also a stretch and subsequent recovery in the cross direction (CD), the multi-layer film material exhibits elastic properties CD substantially identical to the central layer of elastic film itself. As such, the stretched and recovered CD version of this multilayer film exhibits an enhanced anisotropic elastic behavior. However, before stretching and recovering the film is generally elastic in both MD and CD directions.

The anisotropic elastic behavior in these co-extruded laminates using the anisotropic film layers of the invention can be accentuated as described in the Patent of E. U. A. No. 5, 462, 708 by subjecting the stretched uniaxially rolled product to a heat deactivating treatment, while in the stretched condition. The heat treatment is such that the elastic force of recovery of the elastic material is allowed to dissipate without substantially affecting the orientation of the inelastic coating materials. The thermally treated laminate is then stretched in a second crossed direction and allowed to recover as described above. The resulting material is excessively strong in the original elastic direction and is elastic in the cross direction. The orientation of the grain direction can also be used in other embodiments, with or without heat treatment, to provide additional anisotropic behavior to the material of the anisotropic film of the invention. This orientation of the grain direction can be up to the natural proportion of the trace of the fiber-forming polyolefins of the inelastic portion of the polymer. Generally this can be an orientation of up to six (6) times the original length of the film, although preferably from 2 to 5 times the original length of the film.

In a further embodiment, an extremely thin coating layer can be employed in such a manner that the multilayer elastomeric material exhibits substantially complete elastic properties when initially stretched in the CD direction, rather than requiring stretching and initial recovery. The use of such a thin coating layer generally decreases the potential of the anisotropic film to block when formed on a roll, however, generally these coating layers are not required for this purpose. If the coating layers are used, the elastic film layer may contain additional materials in the portion of the elastomer which increases the adhesion of the film layers and as such their tendency to block. Such additives include dual block copolymers as discussed above, other adhesion modifying elastomers such as polyisoprenes, adhesives, oils, liquid or low molecular weight resins and the like. Adhesion modifying materials can assist in the adhesion of the coating layer to the core layer or can be used to modify the elastomeric properties, extrusion properties that can be used as expanders.

The anisotropic elastic film of the invention can also be used extensively in laminated products with other film layers or woven nonwoven materials or other lattices such as are known in the art. For example, the anisotropic elastic film can be bonded by extrusion directly to a non-woven material which is extensible in at least the cross direction or alternatively either adhesive or thermally bonded continuously or glued to such patterned material. Examples of such cross-directionally sensitive sensitive nonwoven webs include the rotatable, glue-bonded, stick-bonded, stretchable webs disclosed in U.S. Patent No. 5,514,470.

These non-woven webs are stretchable in the direction of the grain, for example, at an elongation of 150%, such that the lattice or lattice reversibly and substantially narrows the cross direction and then attaches to the elastic film layer while It is narrowed. The resulting laminate is generally tensioned in the direction of the grain while it is generally elastically extensible in the cross direction. In turn, a nonwoven web film may be corrugated in the cross direction by the use of corrugating rollers and subsequently joined to the anisotropic elastic film of the invention. Other certain non-woven materials such as some nonwoven materials wound by rotation or rotating non-woven materials formed of wrinkled or wrinkled fibers exhibit a natural tendency to elongate in the cross direction.

The anisotropic elastic film of the invention, whether a single-ply film, or a multilayer film, or a laminate can be used extensively in disposable or limited-use garments and the like that requires elasticity of elastic display generally in cross direction For example, the material can be used extensively, as an elastic in a disposable diaper such as an elastic waistband, elastic side panels or elastic auditory portions as in disposable sports pants that require specific zones of elasticity in order to create a comfortable fitting garment. tight. When used, the anisotropic elastic film material of the invention is generally unwound from a roll and cut into shapes and sizes suitable for use in the elastication of the disposable garment. The relatively inelastic behavior of the anisotropic film in the direction of the grain allows the film to be handled more easily and cut in specific ways with conventional film handling machinery without unwanted elongation of the elastic (for example, causing loss of the line). of manufacture) in the grain direction. The material of the invention when cut into appropriate shapes can be applied in a conventional manner as is known in the art.

The material of the invention can be formed by conventional methods of film exclusion either as a single layer or as a multiple layer in such a manner as specifically described in the examples. The materials are generally fed into one or more rotary pin extruders that are fed to a die or feed block through which the tip of the die forms the extruded elastic film. If the material is coated by extrusion directly into a non-woven material the non-woven material generally approaches in less than two seconds after the film is extruded into the die die so as to contact the non-woven material while in a been substantially softened by heat.

Methods of Analysis 1. Tear resistance One end of a sample approximately 75mm long and exactly 63mm wide is placed in a vertical plane with the long dimension extending horizontally, with the ends of the sample held between a pair of horizontally fixed pliers spaced at 2.5mm from a pair of mobile tongs that grip the other end of the sample to be analyzed. A 20mm cut is made in the lower flange of the test sample between the two pairs of pliers. A pendulum, which transports a graduated circumferential scale, is then allowed to fall freely, tearing the pre-cut test sample along a continuation of the cut. A pointer mounted by friction on the scale indicates the resistance in grams of the sample to tearing. Commonly it refers to the analysis as the resistance to tearing Elmendorf (ASTM S1922) and the values are reported in grams per thousand (25 microns).

Each of the elastic films of the present invention were quantified 6 times. A normalized value was calculated by dividing the analysis sample by the thickness of the sample. The normalized values thus obtained are averaged. The quantifications are made in such a way that the tearing of the sample of the analysis propagates along the direction of the grain (MD). 2. FIO and FIO ratio Strips of the elastomeric film measuring 2.54cm by 15cm are cut along both the grain direction (MD) and the cross direction (CD) with an extruded film sheet.

The FIO force required to stretch each of the samples by 10% is quantified using a standard voltage analysis configuration as described in ASTM D 882-95 a. Each of the quantifications was made in three samples. The force obtained is then divided by the thickness of the sample in mils to give a normalized value of the force. Each quantification was done 3 times and the results of the normalized force are averaged.

The FIO force required to stretch the elastomeric film by 10% of its original length in the direction of the grain in the cross direction, respectively, is compared to one another in a proportion and refers to them as the FIO ratio in the tables of data in the following examples. The proportion is a number without dimension.

The FIO force normalized by cross-sectional area (CD) is also reported for the films in the tables. 3. Permanent Fixed Specifically, samples of elastomeric film having a thickness of 2.54cm and a length of 15cm are cut into strips.

The elastomeric films of the present invention are stretched to a given percentage of their original length and then allowed to recover. This tendency to fully recover to remain partially extended after stretching is determined quantitatively by quantifying the permanent fixation in percentages. The analysis was carried out using a tension tester and an array of test samples as described in ASTM D 882-95 a, Tensile Properties of Thin Plastic Sheet Formation. The samples of elastomeric film extend up to 200% of their original length, they are maintained at that extension for 5 seconds, they are allowed to relax, they are quantified again after 5 seconds. Each elastomeric film is quantized 3 times in the cross direction and then the data is averaged.

The difference in length before and after the extension is divided by the original length that is expressed as a percentage. materials Elastomers Styrene-isoprene-styrene block copolymer, 15% styrene, 83% triple block, available as Kraton 1107 from Shell Chemical Co, Houston, Texas. E2 Styrene-butadiene block copolymer. styrene, 31% styrene, available as Kraton 1101 from Shell Chemical Co, Houston, Texas. E3 Styrene-ethylene / butylene-styrene block copolymer, 13% styrene, 65% triple block, available as Kraton 1657 from Shell Chemical Co, Houston, Texas.

E4 Styrene-isoprene-styrene block copolymer, 20% styrene, 100% of the triple block available as Vector 4111 from Dexco Polymers, Houston, Texas. E5 Styrene-isoprene-styrene block copolymer, 29% styrene, 100% triple blkoque, available as Vector 4211 from Dexco Polymers, Houston, Texas.

Fiber Formation Materials F21 High density polyethylene (HDPE), available as LT6186, 0.96 d, 0.8 MFI, from Quantum Chemicals, Cincinnati, OH. F22 High density polyethylene (HDPE), available as 1288 from Fina Oil and Chemical, Dallas, TX. F23 Polypropylene (PP) available as 5 A95, MFI 9.5, from Union Carbide, Danbury, CT. F24 Polypropylene (PP) available as 5D45, MFI 0.8, from Union Carbide, Danbury, CT. F25 Polypropylene (PP) available as Escoreno 3085, MFI , by Exxon Chemical, Houston, TX. F26 Polypropylene (PP) available as Escoreno 1012, MFI , Exxon Chemical, Houston, TX. F27 Polypropylene (PP) available as Dypro 3857, MFI 70, Fina Oil and Chemical, Dallas, TX.

F29 Polypropylene (PP) available as Dypro 3860 MFI 100, Fina Oil and Chemical, Dallas, TX. F30 Polypropylene (PP) available as Escoreno 3505, MFI 400, Exxon Chemical, Houston, TX. F31 Polypropylene (PP) available as 442H, 1000 MFI, from Montell North America, Wilmington, Delaware. F32 Propylene and ethylene random copolymer (P-co-E), melt flow index (MFI) 1.5, available as EOD95-08 of FinaOil and Chemical, Dallas, TX. F33 Polypropylene / ethylene-propylene rubber (PP / EPR), block impact copolymer, MFI 8, available as 7C50 from Union Carbide, Danbury, CT. F34 General purpose crystalline polystyrene (PS), mfr 4, available as 535BP1 from Fina Oli and Chemical, Dallas, TX. F35 Polystyrene (PS), available as G18, MFI 18, from Oco Polymers, Alpharetta, Georgia. F36 Polypropylene / ethylene-propylene rubber (PP / EPR), block impact polymer, available as WRD-5-1057, 12 MFI, available from Union Carbide, Danbury, TX. F37 Polypropylene (PP), 2.5 MFI, available as 3374 from FinaOil and Chemicals, Dallas, TX. F38 Polypropylene (PP), MFI 3.9, available as 5 A97 from Union Carbide, Danbury, TX.

F39 Polypropylene (PP), MFI 12, available as 5-1057 of Union Carbide, Danbury, TX. F40 Random copolymer of propylene and ethylene (P-co-E), 3. 2% ethylene, 1.9 MFI, available as 6D20, from Union Carbide, Danbury, TX.

Additives / Others A51 Calcium Carbonate (CaC03), commercially available as G200 CaC03 with 80:20 ethylene propylene rubber, from Omya, GmbH, Cologne, Germany. A52 Processing oil, available as Shellflex 371, from Shell Chemical Co, Houston, Texas. A53 Impact polypropylene copolymer, available as SRD-7-560, MFI 30, from Union Carbide, Danbury, CT. This material is used in multi-layer films as a "coating" layer.

General methods of film extrusion Method 1 - Single layer film extrusion Single layer films are prepared by extrusion using a single bolt extruder having a bolt diameter of 1.9cm and a length / diameter ratio of 24: 1, commercially available from Haake (paramus, NJ). The barrel is heated in 3 zones at temperatures of 163 ° C, 182 ° C and 218 ° C, respectively, the temperature increases in the direction of the die.

The materials are combined by mixing compressed or crumbled versions of commercially available products and feeding these mixtures by gravity into the extruder. The exit of the extruder was adapted with a slot in the die of 2cm wide that was adapted to extrude the thickness of the film to generally approximately 100 microns.

The films are formed by emptying them in a cutout creating a roll coated with silicone rubber, a roll of stainless steel with a matte finish, of which both are cooled approximately 10 ° C with chilled water.

The finished films are wound on a roll at a speed of approximately 3m / min and stored in roll form at approximately 22 ° C. In cases where it is anticipated that the films may have the tendency to irreversibly adhere to themselves, a release liner of silicone-coated paper is wound together with the film on the roll. The resulting films were not stressed.

All example films and comparative examples are prepared by this method unless otherwise indicated.

Method 2 - Extrusion of multi-layer films A continuous co-extrusion was carried out to prepare the 3-layer laminates with 2 layers of external coating and one core layer. A Davis Standard extrusion with a bolt diameter of 6.3 cm is used to feed the core layer and a Davis Standard extrusion with a bolt diameter of 3.8 cm (available from Davis Standard Corp., Pawcatuck, CT) is used to feed the two coating layers in the Cloeren (TM) feed block. The three layers are extruded through a single 46cm wide multiple film die. The resulting films do not get stressed.

Method 3 - Extrusion of single layer films with orientation Single layer films are prepared by continuous extrusion using an extruder and with a bolt diameter of 4.4cm and a L / D ratio of 24: 1. Four barrel zones of the extruder are heated to 171 ° C, 193 ° C, 204 ° C and 216 ° C, respectively and the die groove at 216 ° C. The films are formed by emptying them in a cut formed by a hole covered in silicone rubber and a metal roll with a matt finish. Both are cooled with water at 10 ° C. Then the movies are enrolled in a roll.

In a subsequent step, the film is oriented in the grain direction first by preheating to 104 ° C and then stretching the softened film between the 2 cut-outs, n where the second cut is running at a higher speed than the first cut.

Examples Comparative Example 1 and Example 1 Comparative Example 1 is prepared by extruding a single layer of synthetic rubber from isomer-isoprene-styrene, denoted as El (styrene-isoprene-styrene copolymer block, 15% styrene, 83% block triple, available as Kraton 1107 from Shell Chemical Co, Houston, Texas), using the technique described in Method 1.

Example 1 is prepared in the same manner as Comparative Example 1, except that 50 parts of high density polyethylene (HDPE) are added to 50 parts of an elastomer based on styrene-isoprene-styrene while being fed into the extruder . High density polyethylene (HDPE) referred to as F21, is available as LT6186, 0.96 d, 0.8 MFI, from Quantum Chemicals, Cincinnati, OH.

The chemical composition of the films of the examples is expressed as a percentage by weight unless indicated otherwise.

Extruded films are evaluated by the above methods of analysis: FIO ratio (ratio of the force required to stretch the film to 10% in the grain direction against the cross direction), permanently fixed after elongation to 200% and the torn Elmendorf. The results of the analysis are also recorded in Table 1.

Comparative Example 2 and Examples 2 to 4 A second Comparative Example is prepared in an identical manner to Comparative Example 1, except that a different styrene-isoprene-styrene elastomer is employed. The elastomer used in this example, designated as E4 in the Tables, is 20% styrene, 80% isoprene and 100% triple ABA block, available as vector 4111 from Dexco Polymers Houston, Texas.

Examples 2 to 4, respectively, are prepared using Method 1 by adding a high density polyethylene (HDPE) with the type quantities described in Table 1 for the base E4 elastomer. The samples are analyzed in the previous examples and the results are recorded in Table 1.

Table 1 The addition of HDPE to the SIS elastomer produces anisotropic elastic films whose films also exhibit a substantially improved tear strength in grain direction.

Examples 5 to 17 Examples 5 to 17 are also prepared by the general method (Method 1) for extruding single layer films, again using styrene-isoprene-styrene block polymers denoted as El and E4 as elastomeric bases. In this group of Examples, however, various polypropylenes having various melt indexes were used as fiber-forming additives. In Examples 6 to 9, respectively, an ethylene-propylene copolymer denoted as F32, used in Example 15, a high density polymer (HDPE), denoted as F21, is added.

This set of Examples is started under very similar conditions during a period of several consecutive hours.

The material compositions and the results of the analysis are summarized in Table 2.

Table 2 All elastomer films in these Examples exhibit an anisotropic behavior with higher strength values than the isolated base elastomer. Extremely low MFI polypropylene, less than 1, does not provide an anisotropic behavior as high as higher MFI polypropylenes (greater than 2.0).

Examples 18 to 28 The elastomeric films of the invention are prepared in Examples 18 through 26 by extruding a styrene-isoprene-styrene block copolymer elastomer in combination with a series of polypropylenes having a wide range of melt flow rates.

Another Example 27 is prepared using a random copolymer of ethylene and propylene, commercially available as EOD95-08 from Fina Oil & Chemical.

Another Example 28 is prepared using an impact copolymer available as Tc50 from Union Carbide.

Comparative Examples 1 and 2 are included in Table 3 for reference. The compositions of the materials and the results of the analysis are shown in Table 3 Table 3 Generally all polypropylenes worked but those in a preferred MFI range of about 2.5 to 40 exhibit the best combination of anisotropic behavior and tear resistance.

Examples 29 to 30 The elastomeric films of the invention are prepared using two different types of block polymer in combination with an isolated polypropylene in the form of a fiber material. Example 29 is prepared using the styrene-isoprene-styrene block polymer, denoted as El. Example 30 is prepared in the same manner as Example 29, except that the block polymer is styrene-butadiene-styrene is used as an elastomer base material. The compositions of the films and the results of the analysis are summarized in Table 4. Table 4 Examples 31 and 32 The elastomeric films of the invention are prepared by adding a random copolymer of propylene and ethylene (P-co-E) to two different block polymers. Example 31 employs a styrene-isoprene block polymer. styrene, denoted as El.

Example 32 employs the fiber-forming propylene-ethylene copolymer in the same amount as the Example 31, but in combination with a different elastomer, a styrene-ethylene / butylene-styrene block copolymer, denoted as E3.

The compositions of the film and the results of the analysis are summarized in Table 5. Table 5 Example 33 Example 33 is prepared by combining a SIS block polymer in a manner denoted as E5 (60 parts) and a polypropylene denoted as F23 (35 parts) in a processing oil denoted as A52 (5 parts), commercially available as Shellflex 371 from Shell Chemical, Houston, TX.

The quantifications of the analysis show the proportion of FIO as 5.47, a tear of 81 g / 25μ, and a permanent fix of 20.9%.

Examples 34 to 36 The elastic films of the present invention are excluded using Method 1 except that the calcium carbonate commercially available as Omya G200 from Omya was added to the polymer blends of Examples 35 and 36 as they were fed into the extruder Example 34 does not contain calcium carbonate.

The chemical composition of the films as well as the results of the analysis are summarized in Table 6. Table 6 All the films can be unrolled but the addition of calcium carbonate dramatically decreased the force needed to unwind the films.

Comparative Examples 3 to 6 Comparative Examples 3 to 6 are prepared to demonstrate the effects of using polystyrene as a fiber-forming material as disclosed in Japanese Kokai Application No. 5-186611.

Comparative Examples 1 and 2, previously described, showing the base materials of elastomers that do not have a fiber-forming polymer material, are included in Table 7 for comparative purposes.

The compositions of the films and the results of the analysis are summarized in Table 7.

Table 7 Adjacent layers in the roll adhered permanently to one another. No unwinding value could be quantified.

Although these films (C3-C6) exhibit very good anisotropic elastic qualities the tear resistance is poor and the films can not be unrolled or unrolled with great difficulty.

Comparative Examples 7 to 12 These Comparative Examples are prepared as in Comparative Examples 3 to 5 above. The C7 film of the isolated elastomer base material is prepared on the same day with the same batch of the polymer to ensure an internal consistency of the results of the analysis.

The compositions of the film and the results of the analysis are summarized in Table 8 Table 8 These films are not analyzed for unwinding but generally they were quite sticky and improbably not unrolllable. The tear results are uniformly poor, decreasing with the increased addition of polystyrene.

Examples 37 to 40 and Comparative Example 13 Examples 37 to 40 are prepared using the coextrusion technique described above above in Method 2 of the General Methods.

Examples 37 to 40 consist of 1) a core comprising an elastomer and fiber-forming materials and 2) two thinner coating layers, one on both sides of the thicker-sided core, resulting in the 3-layer structure coating-core-coating. The coating layers comprise the polymer denoted as A53, the impact polypropylene polymer, available as SRD-7-560, MFI 30, from Union Carbide, Danbury, CT.

A comparative example having coatings, but not having a fiber-forming polymer in the center, is included as Comparative Example 13. The composition as well as the results of the analysis are summarized in Table 9. Table 9 The coating layers themselves are somewhat oriented in the coextrusion process and as such create anisotropic behavior in the C13 film. The addition of polypropylene to the core layer increased the anisotropic behavior more.

Examples 41 to 47 and Comparative Examples 14 and 15 A series of examples are prepared wherein the amount of fiber-forming material varies in a wide range from about 0% to 100%.

Comparative Example 2 described above and represents the base of the elastomer with material that does not form fibers, is included again for comparative purposes.

Comparative Example 15 represents polypropylene in its pure state or without a base elastomer material.

Examples 41 to 47 show the styrene-isoprene-styrene base elastomer, denoted as E4, in combinations with propylene (PP), denoted as F23, in amounts in a range from 20% to 60%, with the Comparative Example 14 having 75% polypropylene.

The compositions of the materials as well as the results of the corresponding analyzes are shown in Table 10. Table 10 Improvements in tear strength do not occur, with this particular combination of elastomer and polypropylene, until after 35% polypropylene is added. Although the tear strength is improved with respect to this combination of materials at 35% polypropylene in Example 34. This variability is often noted and is probably due to variations in processing conditions such as mixing, conditions of extrusion, or similar or variability in the polymer batch. However, generally the same propensities are noted with any given selection of materials processed under identical low conditions in terms of properties such as tear resistance and anisotropic elastic behavior. (generally the addition of a polyolefin did not adversely affect the tear whereas polystyrene generally did adversely affect tear resistance). And hit level improved tear resistance. The addition of polyolefins also generally resulted in a maximum anisotropic behavior at a certain level (generally 30 to 50% polyolefins) with decreases on either side of the maximum value. The amount of permanent setting also generally increased linearly with the addition of polyolefins until it became unacceptable (generally at a ratio of 0.4: 1 to 0.6: 1 portion of elastomer to polyolefin portions).

Examples 48 to 51 Examples 48 to 51 were characterized using an identical polymer composition, containing 50% styrene-isoprene-styrene block polymer (E4) as the base elastomer, 50% by weight of the random copolymer of propylene and ethylene (P-) co-E) '(F32).

Example 48 represents the elastomeric film extruded in a disoriented state.

In Examples 49 to 51, the extruded polymeric films are extracted in the directions of the grain according to Method 3 in the amounts of 1.5 times, 2.0 times and 2.5 times, respectively.

The composition of the film and the results of the analysis are summarized in Table 11.

Table 11 The orientation after extrusion improved the elastic anisotropic properties of the films. Generally, the tear strength was not significantly affected during orientation of the grain direction.

Claims (11)

1. An anisotropic elastic lattice characterized in that it comprises an anisotropic elastic film layer having a grain direction and a cross direction of a thickness of 20 to 300 microns formed by an extruded combination of the portion of a block copolymer elastomer and a portion of polyolefin polymer combined in a ratio of 10: 1 to 0.4: 1, respectively, the elastomer portion comprises a block copolymer elastomer formed by A blocks and B blocks, A blocks are predominantly formed of monoalkenyl arene and B blocks are predominantly formed of isoprene, the polyolefin portion comprises predominantly of an inelastic fiber-forming polymer comprising a propylene polymer, copolymer or combination of a combination of high density polyethylene, wherein the anisotropic film layer has an FIO ratio ( MD to CD) of at least 2.0 and a permanent fix to 200% stretch less than 50%.

2. The anisotropic elastic framework according to claim 2, characterized in that it comprises a roll of a monolayer film having an unwinding force of less than 300 g / 2.54cm, and wherein the FIO fierce in the grain direction is larger than the unwinding force.

3. The anisotropic elastic framework according to claim 1, characterized in that the framework comprises a multi-layer film of this cpa of anisotropic elastic film and at least one other layer of polymer film wherein at least one other layer of polymer film is a relatively inelastic film layer compared to this layer of elastic film.

4. The anisotropic elastic framework according to claim 3, characterized in that at least one other layer of polymer film is a layer of polyolefin film.

5. The anisotropic elastic framework according to claim 3, characterized in that at least one other layer of polymer film comprises two of these layers of film one on either side of this layer of anisotropic elastic film, wherein these layers of film coextruyen.

6. The anisotropic elastic framework according to claim 1, characterized in that this polyolefin portion is a copolymer of propylene polymer or combination having an MFI of at least 1.0, and wherein this proportion of the elastomer portion to the portion of Polyolefin is from 5: 1 to 0.6: 1.

7. The anisotropic elastic framework according to claim 6, characterized in that this portion of the block copolymer elastomer is predominantly a multi-block copolymer wherein this multi-block copolymer comprises from 50 to 100% by weight of the block copolymer and the portion of the elastomer and this polyolefin portion has an MFI of 2.5 to 40.

8. The anisotropic elastic framework according to claim 6, characterized in that this layer of anisotropic elastic film has an average tearing strength of at least 20g / 25μ at an FIO ratio of at least 2.5.

9. The anisotropic elastic framework according to claim 1, characterized in that this anisotropic elastic framework comprises a laminated product of this layer of anisotropic elastic film at least a second non-woven sharp fabric which is extensible in at least the cross direction of the anisotropic elastic film layer to which the second lattice sticks.

10. The anisotropic elastic framework according to claim 1, characterized in that the anisotropic elastic film is oriented in the grain direction up to the natural proportion of the fiber-forming polyolefin trace, wherein the anisotropic elastic film has an FIO force in the cross direction of less than about 60 kg / cm2.

11. The anisotropic elastic framework according to claim 1, characterized in that the anisotropic elastic film has an FIO force in the cross direction of at least about 20 kg / cm2. ENTRAMADOS AND ANISOTROPIC ELASTIC FILMS SUMMARY An anisotropic elastic lattice, particularly an anisotropic elastic film layer having a grain direction and a cross direction and having a thickness from 20 to 300 microns formed from an extruded combination of a portion of a block copolymer elastomer and a portion of polyolefin polymer mixed in a ratio from 10: 1 to 0.4: 1, respectively. The elastomer portion is generally a block copolymer elastomer formed of blocks A and B blocks, blocks A are predominantly monoalkenin arene and blocks B are predominantly conjugated diene. The polyolefin portion is predominantly comprised of an inelastic polyolefin polymer, fiber-forming polymer, copolymer or blend. The anisotropic film layer has a FIO force ratio (MD to CD) of at least 1.5. This elastic anisotropic film lattice is usable in a variety of garment applications where an elastic material is provided in rolled form and requires strength in grain direction and elastic properties in the cross direction.