MXPA01013179A - Stretchable, conformable protective covers. - Google Patents

Abstract

The present invention provides a flexible cover (10) comprising at least one sheet of flexible sheet material assembled to form a semi-enclosed container having a periphery. The cover (10) is expandable in response to forces exerted by an article, item, or material over which the cover is placed to provide an increase in volume of the cover such that the cover accommodates the articles, items, or material placed therein.

Description

ADJUSTABLE, EXTENDABLE PROTECTIVE COVERS FIELD OF THE INVENTION The present invention relates to flexible covers of the type commonly used for the protection of various articles and / or materials.

BACKGROUND OF THE INVENTION Flexible covers, particularly those made of comparatively cheap polymeric materials, have been widely employed for the protection of various articles and / or materials partially or completely, by themselves or in combination with other covers or opposing surfaces. As used herein, the term "flexible" is used to refer to materials that can bend or bend, repeatedly, such that they are manageable and ductile in response to forces applied externally. Therefore, "flexible" is substantially the opposite in meaning to the terms inflexible, rigid or firm. The materials and structures that are flexible, therefore, can be altered in form and structure to adapt external forces and adjust to the shape of objects with which they make contact without losing their integrity. Flexible covers of the commonly available type are typically formed of materials that have consistent physical properties throughout the roof structure, such as spreading, tensioning and / or elongation properties. With such flexible covers, it is often difficult to provide covers that precisely fit the dimensions and volume of the article to be placed therein. An incomplete cover inevitably leaves part of the article or material unprotected against the elements. As a general proposition, where the precise dimensions are not known in advance and / or where it is desired to have a given cover that suits more than one type or size of article, the covers are typically manufactured in dimensions greater than the foreseeable need, to ensure that the item or material can be completely covered. Another consequence that is frequently found is that the covers that fit the article loosely can slip or the wind can cause it to be walked on the article and / or be completely removed from the article. Therefore, it would be desirable to provide a flexible cover that is capable of solidly conforming to the volume and / or dimensions of the articles and / or materials to be protected.

SUMMARY OF THE INVENTION The present invention provides a flexible cover comprising at least one plate of flexible laminar material assembled to form a semi-enclosed container having a periphery. The cover expands in response to forces exerted by an article or material on which the cover is placed, to provide an increase in the volume of the cover such that the cover conforms to the articles or materials where it is placed.

BRIEF DESCRIPTION OF THE DRAWINGS While the specifications conclude with the claims that particularly indicate and claim the present invention, it is believed that the present invention will be better understood from the following description and taking into account the figures of the accompanying drawings, wherein the reference numbers are retained the same when dealing with identical elements or with similar functions, and wherein: Figure 1 is a plan view of a representative flexible cover in accordance with the present invention; Figure 2A is a perspective, segmented illustration of the flexible film polymer film material of the present invention in a substantially tensionless condition; Figure 2B is a perspective, segmented illustration of the flexible film polymer film material in accordance with the present invention in a partially tensioned condition; Figure 2C is a perspective, segmented illustration of the flexible film polymer film material in accordance with the present invention in a higher voltage condition; Figure 3 illustrates a plan view of another embodiment of a sheet material useful in the present invention; and Figure 4 illustrates a plan view of a polymer network material of Figure 3 in a partially stressed condition similar to the representation of Figure 2B.

DETAILED DESCRIPTION OF THE INVENTION CONSTRUCTION OF THE FLEXIBLE BAG Figure 1 represents a currently preferred embodiment of a flexible cover 10 in accordance with the present invention. In the modality represented in Figure 1, the flexible cover 10 includes a cover body 20 formed of a piece of flexible sheet material having an edge 30. The cover 10 is convenient for containing and protecting a wide variety of articles and / or materials, and may initially be flat or preformed in the general two or three dimensional form of the article or material that is intended to be covered. Depending on the desired application and the articles or materials to be protected, the cover 10 may include a closure to form a completely closed cover or may include an elasticised edge to engage an edge of the article. Means may also be included as Velero® type mutual fixation fasteners, unlocked, activatable or protected adhesive systems, rings, cords or the like to secure the cover to the article or around it by external means. Figure 1 shows a variety of regions extending across the surface of the cover. The regions 40 comprise rows of deeply embossed deformations in the flexible sheet material of the body of the cover 20, while the regions 50 comprise interposed regions without deforming. According to the present invention, the body part 20 of the flexible cover 10 comprises a flexible sheet material having the ability to elongate elastically to adapt the forces exerted externally by the articles and / or materials to be protected, in combination with the ability to impart additional strength to the elongation before the material stress limits are reached. This combination of properties allows the cover to initially expand easily in response to external forces exerted by the protected articles and / or materials, controlling the elongation in respective directions. These elongation properties increase the internal volume of the roof by expanding the length of the roofing material. Therefore, the cover exhibits the ability to adapt to the size, shape and geometry of an item and / or material to be covered, expanding where necessary and to the extent necessary to conform to the geometry and surface topography of the article or material to be covered. Additionally, while it is currently preferred to substantially build the entire body of a sheet material having the structure and features of the present invention, it may be desirable under certain circumstances to provide such material in only one or more parts or areas of the body of the cover and not in its entirety. For example, a band of said material having the desired extension orientation could be provided by forming a complete circular band around the body P1413 of the roof to provide a more localized extension property. Product applications for the covers of the present invention, for example: covers for motor vehicles such as automobiles, vans, boats, aircraft, farm equipment and railroad equipment; bicycle covers; covers for application in equipment for cooking outdoors such as gas or charcoal grills; outdoor and indoor furniture; personal protective clothing, including hairdresser's gowns; bandages; covers and coats to paint; sanitary or sterilized items such as surgical or dental tools; table cloths; child seat covers; reconnaissance table covers, covers for automobile windshields; covers for bicycle and motorcycle seats; umbrella type covers; spotlights covers; Sanitary seat covers; aircraft seat covers; covers for motor vehicle components that are exposed during transit; insulated covers for beverage containers; covers for firewood or sawn wood; etc. In the sense of limitation, the sheet material may have sufficient extension or elongation properties to form a deeply stretched cover of convenient size from a flat plate of material, instead of P1413 form a cover by sealing and folding operations.

REPRESENTATIVE MATERIALS To better illustrate the structural characteristics and performance advantages of the flexible covers according to the present invention, Figure 2A provides a partial, highly enlarged perspective view of a segment of sheet material 52 suitable for forming the body 20 of the cover as depicted in Figure 1. Materials such as those illustrated and described herein as being convenient for uses in accordance with the present invention, as well as methods for making and characterizing it, are described in greater detail in the Patent. from the USA No. 5,518,801 of May 21, 1996 for Chappell, et al., The disclosure of which is presented here for reference. Referring now to Figure 2A, the sheet material 52 includes a "stretchable network" of different regions. As used herein, the term "stretchable network" refers to an interconnected and interconnected group of regions that are enabled to extend to some useful degree in a predetermined direction, providing the sheet material with a rubber-like behavior in response to an elongation applied and subsequently released. The stretchable network includes at least one first P1413 region 64 and a second region 66. The sheet material 52 includes a transition region 65 which is at the interface between the first region 64 and the second region 66. The transition region 65 will exhibit complex combinations of the behavior of the first region and of the second region. It is recognized that each embodiment of said sheet materials suitable for use in accordance with the present invention will have a transition region; however, said materials are defined by the behavior of the sheet material in the first region 64 and the second region 66. Therefore, the following description will be with respect to the behavior of the sheet material in the first and second regions only, since it does not depend on the complex behavior of the sheet material in the transition regions 65. The sheet material 52 has a first surface 52a and a second opposing surface 52b. In the preferred embodiment shown in Figure 2A, the stretchable network includes a diversity of first regions 64 and a diversity of second regions 66. The first regions 64 have a first axis 68 and a second axis 69, wherein the first axis 68 is preferably longer than the second axis 69. The first axis 68 of the first region 64 is substantially parallel to the longitudinal axis "L" of the sheet material 52, while second axis 69 is P1413 substantially parallel to the transverse axis "T" of the sheet material 52. Preferably, the second axis of the first region, the width of the first region, is 0.01 inches to 0.5 inches, and more preferably 0.03 inches to 0.25 inches. The second regions 66 have a first axis 70 and a second axis 71. The first axis 70 is substantially parallel to the longitudinal axis of the sheet material 52, while the second axis 71 is substantially parallel to the transverse axis of the sheet material 52. Preferably, the second axis of the second region, the width of the second region, is 0.01 inches to 2.0 inches, and more preferably 0.125 inches to 1.0 inches. In the preferred embodiment of Figure 2A, the first regions 64 and the second regions 66 are substantially linear, continuously extending in a direction substantially parallel to the longitudinal axis of the sheet material 52. The first sheet region 64 has a coefficient of elasticity and a cross-sectional area Al. The second region 66 has a coefficient E2 and a cross-sectional area A2. In the illustrated embodiment, the sheet material 52 has been "formed" such that the sheet material 52 exhibits a resistive force along an axis, which in the case of the illustrated embodiment is substantially parallel to the P1413 longitudinal axis of the network, when subjected to an axial elongation applied in a direction substantially parallel to the longitudinal axis. As used herein, the term "formed" refers to the creation of a desired structure or geometry on a sheet material that will substantially retain the desired structure or geometry when not subject to any elongations or externally applied forces. A sheet material of the present invention consists of at least one first region and a second region, wherein the first region is visually distinct from the second region. As used herein, the term "visually distinct" refers to characteristics of the sheet material that are readily discernible to the naked eye when the sheet material or the objects that shape the sheet material are subject to normal use. As used herein the term "surface longitudinal path" refers to a measurement along the topographic surface of the region in question, in a direction substantially parallel to an axis. The method for determining the surface longitudinal path of the respective regions can be found in the Patent Test Methods section of Chappell et al. incorporated and referenced above. Methods for forming such sheet materials useful in the present invention include P1413 unrestricted way enhanced with plates or rollers coupled, thermoformed, formed with high hydraulic pressure or emptying. While the entire network 52 has been subjected to a forming operation, the present invention can also be carried out by subjecting only part of the network to the forming operation, for example, a part of the material consisting of the body of the bag. 20, as will be described in detail below. In the preferred embodiment shown in Figure 2A, the first regions 64 are substantially planar. That is, the material within the first region 64 is in substantially the same condition before and after the forming step experienced by the network 52. The second region 66 includes a variety of raised elements similar to ribs 74. The elements similar to ribs can be highlighted high or low relief or a combination of these. The rib-like elements 74 have a first axis or major axis 76 that is substantially parallel to the transverse axis of the network 52 and a second or minor axis 77 that is substantially parallel to the longitudinal axis of the network 52. The length parallel to the first axis 76 of the rib-like elements 74 is at least equal and preferably longer than the length parallel to the second axis 77. Preferably, the ratio of the first axis 76 to the second axis 77 is at least 1: 1 or greater and more preferably at least 2: 1 or greater. The rib-like elements 74 in the second region 66 can be separated from one another by amorphous areas. Preferably, the rib-like elements 74 are adjacent to each other and are separated by amorphous areas of less than 0.10 inches, measured perpendicular to the major axis 76 of the rib-like elements 74, and more preferably the rib-like elements 74 they are contiguous and essentially have no amorphous areas between them. The first region 64 and the second region 66 each have a "projected longitudinal path". As used herein the term "projected longitudinal trajectory" refers to the length of a shadow of a region that would be projected by a parallel light. The projected longitudinal path of the first region 64 and the projected longitudinal path of the second region 66 are equal to each other. The first region 64 has a surface longitudinal trajectory, Ll, smaller than the longitudinal longitudinal trajectory, L2, of the second region 66 measured topographically in a direction parallel to the longitudinal axis of the network 52, while the network is in a condition without tension. Preferably, the surface longitudinal trajectory of the second region 66 is at least 15% greater than that of the first region, more preferably at least 30% greater than that of the first region, and more preferably at least 70% greater than that of the first region. region. In general, the greater the surface longitudinal trajectory of the second region, the greater the elongation of the network before finding the force wall. Convenient techniques for measuring the longitudinal path of said materials are described in Chappell et al. incorporated and already mentioned. The sheet material 52 exhibits a modified "Poisson's lateral contraction effect" substantially less than that of a base network which, with this one difference, is of similar material composition. The method for determining the Poisson's lateral contraction effect of a material can be found in the Test Methods section of the Chappell et al. Patent. referred and incorporated. Preferably, the Poisson lateral contraction effect of networks suitable for use in the present invention is less than 0.4 when the network is subject to 20% elongation. Preferably, the networks exhibit a Poisson lateral contraction effect of less than 0.4. when the network is subject to 40, 50 or even 60% elongation. More preferably, the Poisson's lateral contraction effect is less than 0.3 when the net is subject to 20, 40, 50 or 60% elongation. The Poisson's lateral contraction effect of said network is determined by the amount of network material that is occupied by the first and second regions, respectively. As the area of the laminar material occupied by the first region increases, the Poisson's lateral contraction effect also increases. Conversely, as the area of the laminar material occupied by the second region increases, the Poisson's lateral contraction effect decreases. Preferably, the percentage of area of the sheet material occupied by the first area is from 2% to 90% and more preferably from 5% to 50%. Prior art sheet materials having at least one layer of an elastic material will generally have a large Poisson lateral contraction effect, that is, they "narrow" as they elongate in response to an applied force. Network materials useful in accordance with the present invention can be designed to moderate or substantially eliminate the Poisson lateral contraction effect. For the sheet material 52, the direction of the applied axial elongation, D, indicated by arrows 80 in Figure 2A, is substantially perpendicular to the first axis 76 of the rib-like elements 74. The rib-like elements 74 are enabled to straighten or deforming geometrically in a direction substantially perpendicular to its first axis 76, to allow its extension in the network 52. Referring now to Figure 2B, as the network of the sheet material 52 is subjected to an applied axial elongation, D, indicated by arrows 80 in Figure 2B, the first region 64 having a shorter longitudinal surface path, Ll, provides more initial resistive force, Pl, as a result of deformation in the molecular domain, versus the applied elongation. In this step, the rib-like elements 74 in the second region 66 undergo geometric deformation or straightening and offer minimal resistance to the applied elongation. In transition to the next stage, the rib-like elements 74 are aligned with (ie, in the same plane with) the applied elongation. That is, the second region exhibits a change in geometric deformation in the molecular domain. This is the load of the wall of force. In the stage seen in Figure 2C, the rib-like elements 74 in the second region 66 have substantially aligned with (ie, in the same plane with) the plane of the applied elongation (i.e., the second region has reached its limit of geometric deformation) and begins to resist the subsequent elongation by the deformation in the molecular field. The second region 66 now contributes, P1413 as a result of deformation in the molecular field, to a second resistive force, P2, before the elongation applied later. The resistive forces to the elongation that are provided by the deformation in the molecular field of the first region 64 and the deformation in the molecular field of the second molecular region 66, generate a total resistive force, PT, which is greater than the resistive force which is provided by the deformation in the molecular domain of the first region 64 and the geometric deformation of the second region 66. The resistive force Pl is substantially greater than the resistive force P2 when (Ll + D) is less than L2. When (Ll + D) is less than L2, the first region provides the initial resistive force Pl and generally satisfies the equation: Pl = (Al x The x D) Ll When (Ll + D) is greater than L2 the first and second regions provide a total resistive force PT before the applied elongation, D, and generally satisfies the equation: PT = (Al X The x D) + (A2 x E2 x | Ll + D - L21) Ll L2 P1413 The maximum elongation occurs while in the stages corresponding to Figures 2A and 2B, before reaching the stage described in Figure 2C, and consists of the "available extension" of the network material formed. The available extension corresponds to the distance over which the second region undergoes geometric deformation. The range of available extension can be varied from 10% to 100% or more, and can be largely controlled by the extent to which the longitudinal longitudinal trajectory L2 in the second region exceeds the longitudinal longitudinal trajectory Ll in the first region and the composition of the base movie. The term "extension available" is not intended to imply a limit to the elongation to which the network of the present invention can be subjected, since there are applications where an elongation beyond the available extension is desired. When the sheet material is subject to an applied elongation, the sheet material exhibits a behavior similar to the elastic as it extends in the direction of the applied elongation and returns to its substantially stress-free condition, once the applied elongation is removed, unless that the laminar material extends beyond the point of elasticity limit. The laminar material is able to withstand multiple cycles of applied elongation without losing its ability to P1413 recover substantially. Therefore, the network is able to return to its condition substantially without tension once the applied elongation is removed. While the sheet material can be easily and reversibly extended in the direction of the applied axial elongation, in a direction substantially perpendicular to the first axis of the rib-like elements, the network material is not so easily extended in a substantially parallel direction to the first axis of the rib-like elements. The formation of rib-like elements allows the rib-like elements to be geometrically deformed in a direction substantially perpendicular to the first or greater axis of the rib-like elements, while a deformation in the molecular domain is required to extend in one direction substantially parallel to the first axis of the rib-like elements. The amount of applied force required to extend the network depends on the composition and cross-sectional area of the sheet material and the width and spacing of the first regions, where the first narrower and more widely spaced regions require the application of additional minor forces to achieve the desired elongation, for a composition and an area P1413 cross section given. The first axis, (i.e., the length) of the first regions is preferably greater than the second axis, (i.e., the width) of the first regions with a preferred length-to-width ratio of 5: 1 or greater. The depth and frequency of the rib-like elements can also be varied to control the available extent of a network of laminar material suitable for use in accordance with the present invention. The available extension is increased if for a given frequency of rib-like elements, the height or degree of training imparted on the elements similar to ribs increases. Similarly, the available extension is increased if for a given height or degree of formation, the frequency of the rib-like elements increases. There are several functional properties that can be controlled through the application of said flexible cover materials of the present invention. The functional properties are the resistive force exerted by the sheet material against an applied elongation and the available extension of the sheet material before the force wall is found. The resistive force exerted by the sheet material against an applied elongation is a function of the material (ie, composition, molecular structure and orientation, etc.) and the P1413 area of the cross section and the percentage of the projected surface area of the sheet material that is occupied by the first region. The higher the percentage of the covered area of the sheet material by the first region, the greater the resistive force that the net will exert against an elongation applied for a given composition of material and cross-sectional area. The covered percentage of the laminar material for the first region is determined partly, if not completely, by the widths of the first regions and the adjacent separations between the first regions. The available extension of the network material is determined by the longitudinal trajectory of the second region. The surface longitudinal trajectory of the second region is determined, at least in part, by the spaces of the rib-like elements, the frequency of the rib-like elements and the depth of formation of the rib-like elements measured perpendicularly to the plane of the ribs. material of the network. In general, the greater the surface longitudinal trajectory, the greater the available extension of the network material. As discussed above with respect to Figures 2A-2C, the sheet material 52 initially exhibits a certain resistance to elongation provided by the P1413 first region 64 while the rib-like elements of second region 66 support geometric movement. As the rib-like elements pass into the plane of the first regions of the material, an increased resistance to elongation is exhibited, while the entire sheet material supports deformation in the molecular domain. Therefore, sheet materials of the type shown in Figures 2A-2C and described in the patent for Chappell et al. incorporated and referenced, provide the advantages of the performance of the present invention when they conform to covers of the present invention. An additional benefit achieved by using the aforementioned materials in constructing flexible covers in accordance with the present invention is the increase in visual and tactile attraction of said materials. The polymer films commonly used to form such flexible covers are typically and comparatively thin and frequently have smooth and shiny surface finishes. While some manufacturers use a small degree of high relief or other surface textures, covers made of such materials still tend to exhibit a slippery and faint touch impression. The materials assembled with substantially surfaces of P1413 two-dimensional geometry also tend to leave the consumer with an exaggerated impression of weakness, which causes him to perceive a lack of durability of such flexible covers made of polymers. In contrast, the sheet materials useful in accordance with the present invention as depicted in Figures 2A-2C exhibit a three-dimensional cross-sectional profile, wherein the sheet material is (in a tensionless condition) deformed away from the predominant plane of the material laminate. This provides an additional surface area to be able to take the material by hand and dissipates the brilliance normally associated with smooth, flat surfaces. The three-dimensional rib-like elements also provide a "cushioned" tactile impression when the cover is held in the person's hand, also contributes to a desirable tactile impression with respect to conventional cover materials and provides a reinforced perception of thinness and durability . The additional texture also reduces the noise associated with certain types of film materials, leading to an improved aural impression. Suitable mechanical methods for forming the base material in a network of laminar material suitable for use in the present invention are well known in this art and are set forth in the aforementioned patent of P1413 Chappell et al. No. 5,650,214 of July 22, 1997 of Anderson et al., The exhibits of which are incorporated herein for reference. Another method for forming the base material in a network of laminar material suitable for use in the present invention is that formed by vacuum. An example of a method for forming by vacuum is set forth in U.S. Pat. No. 4,342,314, by Radel et al. of August 3, 1982. Alternatively, the network formed of sheet material can be formed hydraulically in accordance with the teachings of U.S. Pat. No. 44,609,518 to Curro et al. of September 2, 1986. Exhibits of each of the patents are incorporated herein by reference. The forming method can be performed in a static mode, where a discrete part of the base film is deformed at the same time. Alternatively, the forming method can be carried out using a continuous dynamic pressure, to intermittently contact the moving web and form the base material in a network material formed in accordance with the present invention. This and other convenient methods for forming the network material of the present invention are described in more detail in the incorporated and referenced patent of Chappell et al. The flexible covers are P1413 can be manufactured from formed sheet material or alternatively the flexible covers can be manufactured and then subjected to the methods to form the sheet material. Referring now to Figure 3, other patterns may also be employed for the first and second regions, such as sheet materials 52 suitable for use in accordance with the present invention. The sheet material 52 is shown in Figure 3 in its substantially stress-free condition. The sheet material 52 has two center lines, a longitudinal center line, referred to herein as an axis, line or "L" direction and a lateral or transverse center line, here also referred to as an axis , line or "T" address. The transverse center line "T" is generally perpendicular to the longitudinal centerline "L". The materials of the type shown in Figure 3 are described in greater detail in the aforementioned patent of Anderson et al. Cone was discussed above with respect to Figure 2A-2C, the sheet material 52 includes a "stretchable network" of different regions. The stretchable network includes a diversity of first regions 60 and a diversity of second regions 66 that are visually distinct from one another. The sheet material 52 also includes regions of P1413 transition 65 which are located at the interface between the first regions 60 and the second regions 66. The transition regions * 65 will exhibit complex combinations of the behavior of both the first and second regions, as discussed above. The sheet material 52 has a first surface, (seeing the observer in Figure 3), and a second opposing surface (not shown). In the preferred embodiment shown in Figure 3, the stretchable network includes a variety of first regions 60 and a diversity of second regions 66. A portion of the first regions 60, generally indicated as 61, are substantially linear and extend in a first address. The remaining first regions 60, indicated generally as 62, are substantially linear and extend in a second direction that is substantially perpendicular to the first direction. While it is preferred that the first direction be perpendicular to the second direction, other angular relationships between the first direction and the second direction may be desirable as long as the first regions 61 and 62 intersect with each other. Preferably, the angles between the first and second directions vary from 45 ° to 135 °, with 90 ° being most preferred. The intersection of the first regions 61 and 62 forms a boundary, indicated by shaded lines 63 in P1413 Figure 3, which completely surrounds the second regions 66. Preferably, the width 68 of the first regions 60 is 0.01 inches to 0.5 inches, and more preferably 0.03 inches to 0.25 inches. However, other width dimensions for the first regions 60 may be convenient. Because the first regions 61 and 62 are perpendicular to each other and have the same spacing, the second regions have a square shape. However, other shapes for the second regions 66 are convenient and can be achieved by changing the spacing between the first regions and / or aligning the first regions 61 and 62 with each other. The second regions 66 have a first axis 70 and a second axis 71. The first axis 70 is substantially parallel to the longitudinal axis of the material of the network 52, while the second axis 71 is substantially parallel to the transverse axis of the material of the network 52 The first regions 60 have a coefficient of elasticity El and a cross-sectional area Al. The second regions 66 have a coefficient of elasticity E2 and a cross-sectional area A2. In the embodiment shown in Figure 3, the first regions 60 are substantially planar. That is, the material within the first 60 regions is in P1413 substantially the same condition before and after the forming step to which the network 52 is subjected. The second regions 66 include a plurality of similar elements at raised ribs 74. Rib-like elements 74 may be formed by a high or bas-relief or by a combination of them. The rib-like elements 74 have a first or major axis 76 that is substantially parallel to the longitudinal axis of the net 52 and a second or minor axis 77 that is substantially parallel to the transverse axis of the net 52. The rib-like elements 74 in the second region 66 can be separated from each other by amorphous areas, essentially without forming high relief they are simply formed as spacing areas. Preferably, the rib-like elements 74 are adjacent to each other and are separated by an amorphous area of less than 0.10 inches measured perpendicular to the major axis 76 of the rib-like elements 74, and more preferably, the rib-like elements 74 are contiguous and essentially do not have amorphous areas between them. The first regions 60 and the second regions 66 have a "projected longitudinal path". As used herein the term "projected longitudinal trajectory" refers to the length of a shadow of a region that would be projected by a parallel light. The P1413 projected longitudinal trajectory of the first region 60 and the projected longitudinal trajectory of the second region 66 are equal to each other. The first region 60 has a surface longitudinal path, Ll, smaller than the longitudinal longitudinal path, L2, of the second region 66 measured topographically in a parallel direction, while the network is in a non-voltage condition. Preferably, the surface longitudinal path of the second region 66 is at least 15% greater than that of the first region 60, more preferably at least 30% greater than that of the first region, and more preferably at least 70% greater than that of the first region. the first region. In general, the greater the longitudinal surface trajectory of the second region, the greater the elongation of the network before finding the force wall. For the sheet material 52, the applied axial elongation direction, D, indicated by arrows 80 in Figure 3, is substantially perpendicular to the first axis 76 of the rib-like elements 74. This is due to the fact that rib-like elements. 74 are enabled to straighten or deform geometrically in a direction substantially perpendicular to their first axis 76, to allow their extension in the network 52.

P1413 Referring now to Figure 4, as the network 52 is subjected to an applied axial elongation, D, indicated by arrows in Figure 4, the first regions 60 having the shortest longitudinal trajectory, Ll, impart more initial resistive force, Pl, as a result of the deformation in the molecular field, before the applied elongation corresponding to stage I. Whereas in stage I, the rib-like elements 74 in the second regions 66 undergo geometric deformation or unfolding and offer minimal resistance to the applied elongation. Further, the shape of the second regions 66 changes as a result of the movement of the lattice structure formed by the intersections of the first regions 61 and 62. Therefore, as the lattice 52 is subjected to the applied elongation, the first regions 61 and 62 undergo geometric deformation or bending, thereby changing the shape of the second regions 66. The second regions extend or lengthen in a direction parallel to the direction of the applied elongation and collapse or contract in a direction perpendicular to the direction of the applied elongation. In addition to the aforementioned elastic-like properties, a sheet material of the type shown in Figure 3 and 4 is believed to provide a softer, more similar texture similar to the fabric and the fabric.

P1413 used does not generate as much noise. Several convenient compositions for building the flexible covers of the present invention include substantially impermeable materials such as polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyethylene (PE), polypropylene (PP), aluminum foil and coated paper (waxed, etc.) and uncoated, coated nonwovens, etc., and substantially permeable materials such as cotton, mesh, woven, non-woven or perforated fabrics or porous films, whether predominantly two-dimensional natural structures or formed in three dimensions. Said materials may comprise a simple composition or layer or may be a composite structure of multiple materials. Once the desired sheet materials are manufactured in any desirable and convenient manner, comprising all or part of the materials to be used by the body of the cover, the cover can be constructed in any known and convenient manner, such as those known in US Pat. This technical field for making said covers have a commercially useful form. Heat sealing, mechanical sealing or adhesive technologies can be used to join various components or elements of the cover to themselves or to each other. In addition, the bodies of the covers can be processed by P1413 thermoformed, blown or molded, instead of using folding and joining techniques to build the bodies of the covers of a network or sheet material. While the particular embodiments of the present invention have been illustrated and described, it will be obvious to those with the technical skills in this area that various other changes and modifications may be made without departing from the scope and spirit of the invention. It is therefore intended to cover in the appended claims all those changes and modifications that are within the scope and spirit of this invention.

P1413

Claims (10)

1. CLAIMS: 1. A cover characterized by at least one plate of flexible laminar material assembled to form a semi-enclosed container having a periphery, the cover expands in response to the forces exerted by an article or material on which the cover is placed, to provide an increase in the volume of the cover such that the cover is adapted to the articles or materials placed there. 2. The flexible cover according to claim 1, wherein the flexible cover has an elasticized edge. 3. The flexible cover according to any of the preceding claims, wherein the sheet material includes a first region and a second region comprising the same composition of materials, the first region suffers a deformation in the molecular domain and the second region suffers initially a geometric deformation when the sheet material is subjected to an elongation applied along at least one axis. 4. The flexible cover according to claim 3, wherein the first region and the second region are visually different from one another. 5. The flexible cover as a rule with claim 3 or 4, wherein the second region includes P1413 a diversity of elements similar to ribs. 6. The flexible cover according to claim 3, 4 or 5, wherein the first region is substantially free of rib-like elements. The flexible cover according to any of the preceding claims, wherein the sheet material exhibits at least two significantly different stages of resistive forces to an axial elongation applied along at least one axis, when subjected to the applied elongation in a direction parallel to the axis, in response to a force applied externally on the flexible cover when shaped to give a closed container; The sheet material comprises: a stretchable network including at least two visually distinct regions, one of the regions being configured to exhibit a resistive force in response to the axial elongation applied in a direction parallel to the axis, before a substantial portion of the other of the regions develops a resistive force to the applied axial elongation, at least one of the regions has a longitudinal surface trajectory that is greater than those of the other regions, measured parallel to the axis, while the sheet material is in a condition without tension; The region exhibiting a longer longitudinal surface path includes one or more similar elements P1413 at ribs; the sheet material exhibits a first resistive force to the applied elongation until the elongation of the sheet material is much larger to cause a substantial part of the region to have a longer longitudinal surface path to enter the plane of the applied axial elongation, with the As the sheet material exhibits a second resistive force to the axial elongation applied thereafter, the sheet material exhibits a total resistive force greater than the resistive force of the first region. The flexible cover according to any of the preceding claims, wherein the sheet material exhibits at least two stages of resistive forces to an applied axial elongation, D, along at least one axis, when subjected to elongation axial applied along the axis in response to a force applied externally on the flexible cover, when it is formed as a closed container; the sheet material comprises: a stretchable network of visually distinct regions, the stretchable network includes at least a first region and a second region, the first region has a first surface longitudinal path, Ll, measured parallel to the axis, while the sheet material is in a condition without tension; the second region that has a second surface longitudinal trajectory, L2, P1413 measured parallel to the axis, while the material of the network is in a condition without voltage; , the first superficial longitudinal trajectory, Ll, is smaller than the second superficial longitudinal trajectory, L2; the first region produces by itself a resistive force, Pl, in resp to an applied axial elongation, D; the second region produces by itself a resistive force, P2, in resp to an applied axial elongation, D; the resistive force Pl is substantially greater than the resistive force P2 when (Ll + D) is less than L2. 9. The flexible cover according to any of the preceding claims, wherein the sheet material exhibits a rubber-like behavior along at least one axis, the sheet material comprising: at least a first region and a second region, the The first region and the second region comprise the same composition of the material and each has a longitudinal trajectory projected without tension, the first region supports a deformation substantially in the molecular domain and the second region initially supports a substantially geometric deformation, when the material of the network is subject to an elongation applied in a direction substantially parallel to the axis in resp to a force applied externally on the flexible cover, when it is shaped as a container P1413 closed, the first region and the second region substantially return to their longitudinal trajectory projected without tension when the applied elongation is released. The flexible cover according to claims 3, 7, 8 or 9, wherein the sheet material includes a variety of first regiand a variety of second regicomprising the same material composition, a portion of the first regibeing extends in a first direction while the rest of the first regiextend in a direction perpendicular to the first direction to interconnect with each other, the first regiforming a boundary completely surrounding the second regi P1413