Not applicable.
1. Field of the Invention
The present invention relates to improvements to the structure, composition, and manufacture of polymeric films. Specifically, the present invention relates to improvements to polymeric sheets, particularly those used to cover items and surfaces for protective purposes such as drop cloths used when painting.
2. Description of the Related Art
Polymeric sheets are used in a variety of applications. One particular use of polymeric sheets, also referred to as polymeric sheeting, is as a drop cloth or protective sheet. Polymeric sheeting drop cloths are particularly useful compared to fabric drop cloths when the prevention of liquid penetration is particularly important. For example, it is particularly important to prevent the penetrations of liquids in the context of polymeric sheeting drop cloths used as protective covers during painting or staining.
Polymeric sheeting commercially available today is frequently thin and lightweight. The success of lighter, thinner polymeric sheeting is due, in part, to improvements over the last few decades in both manufacturing and polymer resin technology. The lightweight polymeric sheeting minimizes costs for the consumer and makes the polymeric sheeting easier to transport and simpler to deploy. However, lightweight polymeric sheeting is also more susceptible to movement caused by external forces including, but not limited to, persons walking across the film or when a polymeric sheeting drop cloth is used in drafty or windy conditions. Consequently, it is sometimes desirable to secure the film over or onto an area or surface using adhesive tape or weights along the perimeter of the polymeric sheeting.
One example of a weighted cover cloth is disclosed in U.S. Pat. No. 3,862,876 entitled “Protective Edge Weighted Cover Cloth.” The '876 Patent discloses a protective cover cloth having continuous, flexible weights along at least two opposed edges of the cover cloth. The '876 Patent discloses that the cover cloth may be made from woven, natural, or synthetic fibers, but also suggests that continuous sheet material such as synthetic plastic film may be used. The '876 Patent discloses that sand, shot, or other particulate matter is inserted in a hem or tubes attached along the edges of the cover. To form the hems, the opposed edges are folded back and sewn together to form an elongated pocket or wide hem. According to the '876 Patent, the elongated pocket or hem is subsequently filled with sand, shot, or other granular or particulate weighted material, which is intended to keep the edges of the cover cloth marginally flexible. However, granular fill as disclosed would be time-consuming to load into the cover cloths and construction of the disclosed cover cloth would be generally inefficient in a streamlined manufacturing process. The granular fill would also make the protective covers heavier to transport and more difficult to deploy than other cover cloths. Additionally, the abrasiveness of the granular fill could lead to product failures when used with thin polymeric sheeting films. Moreover, in the event of such failure, the abrasive, granular fill could end up damaging the surface that the cover cloth was meant to protect.
U.S. Pat. No. 4,580,372 provides an example of polymeric sheeting products having apertures with grommets disposed within the apertures. In the '372 patent, the polymeric sheeting product is used in combination with one or more weighted structure secured to the grommets, thereby holding the polymeric sheeting product in place. While the external weight structures serve the desired function, they are bulky and heavy to transport and require significant labor to deploy properly. Additionally, when granular fill is used for the external weight structures, there still exists a real risk of damaging not only the polymeric sheet itself, but also the surface that is intended to be protected.
United States Published Patent Application No. 2010/0154943 entitled “Drop Cloth” also discloses polymeric sheeting products. The '943 Publication discloses using a polyethylene film with hems running along at least one edge of the film. More importantly, the '943 Publication discloses the inclusion of a metal conformable shape retaining member within the hems running along at least one edge of the film, with an aluminum strip being prominently highlighted as a desirable choice for the conformable shape retaining member. The purpose of the conformable shape retaining member is to hold the plastic film in place by creating a rigid structure that is pliable by a consumer. However, such structures are not cost-effective to manufacture, cannot be easily manufactured, and are not easily deployed by a consumer, who must ensure that the conformable shape member in fact conforms to the required shape.
In view of the foregoing, it is desired to provide a solution that addresses the need for plastic drop cloths with enhanced perimeters that are lightweight, easy to manufacture, and can be deployed easily without adding significantly to the cost or complexity of the product.
The present invention is directed to an enhanced perimeter polymeric sheet. The enhanced perimeter polymeric sheet may be comprised of a polymeric film substrate and a first enhanced perimeter region proximate to a first edge of the polymeric film substrate. The first enhanced perimeter region may further comprise an area extending generally along at least a portion of said first edge of the polymeric film substrate. A primary region of the enhanced perimeter plastic sheet may be defined by the polymeric film substrate. The primary region may be located generally inward from the first enhanced perimeter region and the primary region will have a set of attributes. Additionally, the first enhanced perimeter region will have a set of attributes. In such cases, at least one attribute of the set of attributes of the first enhanced perimeter region may differ from a corresponding attribute of the set of attributes of the primary region.
In other embodiments of the present invention, the first enhanced perimeter region may comprise a first enhancement strip disposed on the polymeric film substrate. Additionally, the first enhanced perimeter strip may have a distal edge defining a first perimeter edge of the enhanced perimeter polymeric sheet. In some embodiments, the first enhanced perimeter strip may have a distal edge located inward from the first edge of the polymeric film substrate and the first edge of the polymeric film substrate may define a first perimeter edge of the enhanced perimeter polymeric sheet. In other embodiments, the first enhancement strip may be welded to the polymeric film substrate.
In another embodiment of the present invention, the first enhanced perimeter region may comprise a first enhancement portion integrally provided with the polymeric film substrate. Additionally, the first enhancement portion may be extruded with the polymeric film substrate. Moreover, in another embodiment of the present invention, a first edge of the polymeric film substrate may be folded over to define a first hem. In some cases, a first enhanced perimeter tape may be disposed within the hem. The first hem and the first enhanced perimeter tape may define the first enhanced perimeter region. Additionally, in certain embodiments of the present invention, the set of attributes of the primary region and the first enhanced perimeter region may include at least one of the following: average thickness, weight per unit area, stiffness, color, or texture.
In another embodiment of the present invention, a second enhanced perimeter region may be proximate to a second edge of the polymeric film substrate. Additionally, the second enhanced perimeter region may comprise an area extending generally along at least a portion of said second edge. Moreover, the primary region may be located generally inward from the first enhanced perimeter region and from the second enhanced perimeter region as well. The second enhanced perimeter region will have a set of attributes. At least one attribute of the set of attributes of the first enhanced perimeter region may differ from a corresponding attribute of the set of attributes of the primary region.
In other embodiments of the present invention, a third enhanced perimeter region may be proximate to a third edge of the polymeric film substrate. The third enhanced perimeter region may comprise an area extending generally along at least a portion of said third edge. Additionally, a fourth enhanced perimeter region may be proximate to a fourth edge of the polymeric film substrate. The fourth enhanced perimeter region may comprise an area extending generally along at least a portion of said fourth edge. In such embodiments, the primary region may be located generally inward from the first enhanced perimeter region, the second enhanced perimeter region, the third enhanced perimeter region, and the fourth enhanced perimeter region. Additionally, the third enhanced perimeter region and fourth enhanced perimeter region will each have a set of attributes. At least one attribute of the respective third enhanced perimeter region and fourth enhanced perimeter region may differ from a corresponding attribute of the set of attributes of the primary region.
A full and complete understanding of the present invention may be obtained by reference to the detailed description of the present invention and described embodiments when viewed with reference to the accompanying drawings. The drawings can be briefly described as follows.
The present disclosure illustrates one or more embodiments of the present invention. It is not intended to provide an illustration or encompass all embodiments contemplated by the present invention. In view of the disclosure of the present invention contained herein, a person having ordinary skill in the art will recognize that innumerable modifications and insubstantial changes may be incorporated or otherwise included within the present invention without diverging from the spirit of the invention. Therefore, it is understood that the present invention is not limited to those embodiments disclosed herein. The appended claims are intended to more fully and accurately encompass the invention to the fullest extent possible, but it is fully appreciated that certain limitations on the use of particular terms is not intended to conclusively limit the scope of protection.
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The first enhanced perimeter region 120 and second enhanced perimeter region 122 have one or more enhancements or contrasting attributes when compared to the primary region as described herein. Specifically, in some embodiments of the present invention, the enhancements or contrasting attributes of the one or more enhanced perimeter regions 120, 122 offer visual contrast with the primary region 110 of the enhanced perimeter polymeric sheet 100 by featuring contrasting color, or contrasting color combinations, within the one or more enhanced perimeter regions 120, 122. It would be desirable that the color, or color combinations, of the one or more enhanced perimeter regions 120, 122 visually contrast with the color of the primary region 110 under a variety of lighting and use conditions. In some embodiments, the one or more enhanced perimeter regions 120, 122 may be opaque while the primary region 110 may be clear, translucent, or even opaque with a different color. Furthermore, in other embodiments, the one or more enhanced perimeter regions 120, 122 may be tinted with a color but remain partially transparent or translucent.
In another embodiment of the present invention, one or more enhanced perimeter regions 120, 122 may be thicker than the primary region 110 of the enhanced perimeter plastic sheet 100. For example, in some embodiments of the present invention, the average thickness of one or more enhanced perimeter regions 120, 122 may have an average thickness that is 200% or more than the average thickness of the primary region 110. To wit, in one embodiment of the present invention, the primary region 110 may have an average thickness of approximately 0.5 mils while the one or more enhanced perimeter regions 120, 122 may have an average thickness of 1 mil or greater. Furthermore, in other embodiments of the present invention, the average thickness of the one or more enhanced perimeter regions 120, 122 may have an average thickness that is at least 500% of the average thickness of the primary region 110.
In yet another embodiment of the present invention, the one or more enhanced perimeter regions 120, 122 may have a texture that contrasts with the surface texture (or lack thereof) of the primary region 110. For example, the one or more enhanced perimeter regions 120, 122 may be embossed with a texture or pattern while the primary region 110 of the enhanced perimeter plastic sheet 100 may be substantially smooth. In other embodiments, the primary region 110 of the enhanced perimeter polymeric sheet 100 may be embossed or otherwise textured with a first pattern while the one or more enhanced perimeter regions 120, 122 are embossed or textured with a second pattern that is visually distinguishable from the first embossing pattern. In some embodiments, the one or more enhanced perimeter regions 120, 122 may be distinguishable from the primary region 110 based upon the tactile feel of the respective one or more enhanced perimeter regions 120, 122 in relation to the primary region 110. In other embodiments, the textural differences may be provided through the use of foaming or blowing agents present in one or more enhanced perimeter regions 120, 122 during the extrusion process. However, in other embodiments, the textural differences may be provided during a converting process including, but not limited to, using an embossing wheel on the one or more enhanced perimeter regions 120, 122.
In yet another embodiment of the present invention, the one or more enhanced perimeter regions 120, 122 may be heavier versus the primary region 110 of the enhanced perimeter polymeric sheet 100. In such embodiments, the weight of the one or more enhanced perimeter regions 120, 122 may be greater per unit area than the primary region 110 of the enhanced perimeter polymeric sheet 100. The increased weight per unit area of the one or more enhanced perimeter regions 120, 122 may be accomplished by various methods including, but not limited to, increasing the thickness of the one or more enhanced perimeter regions 120, 122, using materials of increased density within said one or more enhanced perimeter regions 120, 122, or a combination of the foregoing.
In yet another embodiment of the present invention, the one or more enhanced perimeter regions 120, 122 may be stiffer and less flexible than the primary region 110 of the enhanced perimeter polymeric sheet 100. In such embodiments, the one or more enhanced perimeter regions 120, 122 may be thicker, use different materials, or use textures or embossing to modify or change the stiffness within the one or more enhanced perimeter regions 120, 122.
In certain embodiments of the present invention, the one or more enhanced perimeter regions 120, 122 may have two or more of the enhancement attributes described compared to the primary region 110. For example, in certain embodiments, the enhanced perimeter regions 120, 122 may be colored, heavier, and thicker to distinguish the enhanced perimeter regions 120, 122 from the primary region 110.
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The first enhancement strip 220 and the second enhancement strip 222 may be provided on the film substrate 210 using any of several different processes. In some embodiments, the first and second enhancement strips 220, 222 may be extruded, in a supplemental extrusion process, directly onto the film substrate 210 after the film substrate 210 is formed and cooled. In other embodiments of the present invention, the first and second enhancement strips 220, 222 may be co-extruded with the film substrate 210 using a multi-layer die, using die blockers, modified die designs, or a combination of these and other techniques known in the art.
In another embodiment of the present invention, the first enhancement strip 220 and the second enhancement strip 222 may be separately provided and subsequently laminated onto the film substrate 210 through a lamination process that may use adhesives, heat, pressure, or a combination of the foregoing. In other embodiments of the present invention, the first enhancement strip 220 and the second enhancement strip 222 may be separately provided and welded onto the film substrate 210.
In yet another embodiment of the present invention, the first enhancement strip 220 and the second enhancement strip 222 may be provided using a coating or spraying process where the first and second enhancement strips 220, 222 are applied directly to the film substrate 210.
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