The instant invention relates to a method for producing plastic film, more particularly reinforced stretch film or plastic films used for stretch wrapping, and even more particularly, reinforced stretch film employed in pallet wrapping and other applications. The invention also encompasses the reinforced stretch film.
Stretch films are well known and such films are commonly employed, for example, to wrap goods and products of various types positioned on a pallet, the film wholly or partially covering the goods or products and also typically applied to the pallet itself to secure the pallet to the items positioned thereon. The films themselves are typically made of polyethylene, although other stretch film sheet materials can be employed as well.
To reduce packaging costs, it may be desired to use as little stretch film as possible. In addition, to reduce shipping costs by keeping the shipping weight as low as possible and minimizing the space required for shipping, it may be desired for the film to be as light weight and as thin as possible. However, for obvious safety concerns of both the product being shipped and the humans and equipment used in shipping, stretch films need to have high strength. These problems are all interrelated as typically the less film you use, or the lighter and thinner the stretch film is, the less strength it will have. This is especially true for heavier loads (like bricks, cement blocks, bags, drums, steel tubes, pipes etc.) where stretch films are being continuously wrapped around the pallets to achieve load retention. Currently, the safety concerns are strong enough that the stretch film has to be wrapped with heavier gauge material, like straps, bags or stretch hoods, or an immense amount of film with low pre-stretch is used to keep the heavy product secure. However, both of these options clearly increase packaging and/or shipping costs.
Thus, there is clearly a need to create a light weight thin stretch film that has high strength and can create a high force to load. The instant invention is designed to provide a reinforced stretch film that addresses at least some of the above mentioned problems.
The instant invention is directed toward a reinforced stretch film and its method of production. The method of producing the reinforced stretch film includes the steps of: providing an elongated base sheet of plastic stretch film having a longitudinal axis; forming a plurality of cord-like, elongated reinforcement members from a sheet of plastic stretch film other than the elongated base sheet; forming a plurality of plastic film strip overlays from a sheet of plastic stretch film other than the elongated base sheet; positioning the plurality of cord-like, elongated reinforcement members to the elongated base sheet where the cord-like, elongated reinforcement members extend along the longitudinal axis of the elongated base sheet; positioning a plurality of plastic film strip overlay over each of the cord-like, elongated reinforcement members where the plastic film strip overlays being parallel and spaced from one another; folding each edge of the elongated base sheet of plastic stretch film inward toward a center of the elongated base sheet to further strengthen and reinforce each edge; and attaching the plastic film strip overlays and/or the folded edges to the cord-like, elongated reinforcement members and to the elongated base sheet to fixedly sandwich the cord-like, elongated reinforcement members between the elongated base sheet and the narrow plastic film strip overlays. Whereby, the narrow plastic film strip overlays, the folded edges and the cord-like, elongated reinforcement members comprising parallel, elongated reinforcement strips defining elongated spaces therebetween.
The reinforced stretch film includes the elongated base sheet and the plurality of elongated reinforcement strips. The elongated base sheet is made of plastic stretch film and has a longitudinal axis. The plurality of elongated reinforcement strips extend along the longitudinal axis of the elongated base sheet, are disposed substantially parallel to one another, and define elongated spaces therebetween. Each elongated reinforcement strip includes: a cord-like, elongated reinforcement member made from a sheet of plastic stretch film other than the elongated base sheet attached to the elongated base sheet and extending along the longitudinal axis of the elongated base sheet and a narrow plastic film strip overlay made from a sheet of plastic stretch film other than the elongated base sheet positioned over the cord-like, elongated reinforcement member. The reinforcement members are attached to the elongated base sheet and extend along the longitudinal axis of the base sheet. Each of the narrow plastic film strip overlays are positioned over the cord-like, elongated reinforcement members thereof. Each edge of the elongated base sheet of plastic stretch film is folded inward, and over at least one cord-like elongated reinforcement member to further strengthen and reinforce each edge. The narrow plastic film strip overlay and each edge may be attached to the cord-like, elongated reinforcement member and to the elongated base sheet at opposed sides of the cord-like, elongated reinforcement member to fixedly sandwich the cord-like, elongated reinforcement member between the elongated base sheet and the narrow plastic film strip overlay.
For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
The present invention now will be described more fully hereinafter in the following detailed description of the invention, in which some, but not all embodiments of the invention are described. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well as the singular forms, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one having ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In describing the invention, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and the claims.
Referring to the drawings, wherein like numerals, indicate like elements, there is shown in the Figures an embodiment of a reinforced stretch film 1 (see
One embodiment of the instant invention discloses a reinforced stretch film 10 obtained by a method of producing a reinforced stretch film 10 comprising the steps of:
The above method may further include the reinforced stretch film 10 further comprising a plurality of slits through the elongated base sheet 20, the reinforcement strips 50, the folded edges 28, or a combination thereof, which expand into holes when stretched making the reinforced stretch film ventilated. In another embodiment, the above method may further include pre-stretching the reinforced stretch film 10, the elongated base sheet 20, the master material 30 the reinforcement member(s) 35, the overlay(s) 40, the reinforcement strip(s) 50, or a combination thereof. Pre-stretching may be achieved by any means known in the art. In one embodiment of the above method, the pre-stretching may be achieved by passing the above materials through a device in which the level of pre-stretch is adjusted by altering the transmission ratio of two or more power transmission gears operationally associated with a first pre-stretching roller and a second pre-stretching roller, wherein the level of pre-stretch is achieved by passing the materials over the rollers while set at a desired gear ratio.
The elongated base sheet 20 may have a longitudinal axis and be made of any suitable material for a stretch film, including any suitable plastic stretch films. See
Each of the elongated reinforcement strips 50 may be made from a reinforcement member 35 and an overlay 40 (See
The instant invention further includes an additional reinforcement element mentioned previously and now described in more detail. An elongated base sheet 20, as mentioned above includes a longitudinal axis and be made of any suitable material for a stretch film, including any suitable plastic stretch films. An elongated base sheet 20 also includes a pair of edges 25 running parallel to the longitudinal axis and located on each side of the base sheet 20. After one or more elongated reinforcement members 35 are attached to the elongated base sheet 20, extending along the longitudinal axis of the elongated base sheet 20, one or both of the edges 25 of the elongated base sheet may be folded over leaving a folded edge 28 on one or both sides of the elongated base sheet 20. The edges 25 may be folded either prior to or after one or more overlays 40 are attached to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 at opposed sides of the cord-like, elongated reinforcement member 35 to fixedly sandwich the cord-like, elongated reinforcement member 35 between the elongated base sheet 20 and narrow plastic film strip overlay 40 resulting in additional reinforcement of each folded edge 28.
The folded edges 28 and the reinforcement strips 50 of the elongated base sheet 20 may be attached to the base sheet 20 by any means. See
One embodiment of the instant invention discloses a reinforced stretch film 10 comprising an elongated base sheet 20 of plastic stretch film having a longitudinal axis; and a plurality of elongated reinforcement strips 50 extending along the longitudinal axis of the elongated base sheet 20, disposed substantially parallel to one another, and defining elongated spaces 52 therebetween, each elongated reinforcement strip 50 comprising a cord-like, elongated reinforcement member 35 made from a sheet of plastic stretch film other than the elongated base sheet 20 attached to the elongated base sheet 20 and extending along the longitudinal axis of the elongated base sheet and a narrow plastic film strip overlay 40 made from a sheet of plastic stretch film other than the elongated base sheet 20 positioned over the cord-like, elongated reinforcement members 35, where, the narrow plastic film strip overlays 40 are attached to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 at opposed sides of the cord-like, elongated reinforcement members 35 to fixedly sandwich the cord-like, elongated reinforcement members 35 between the elongated base sheet 20 and narrow plastic film strip overlays 40, where each edge 25 of the elongated base sheet 20 of plastic stretch film is folded inward, and over at least one cord-like, elongated reinforcement member 35 creating a folded edge 28 to further strengthen and reinforce each edge, where, each edge 25 of the elongated base sheet 40 is attached to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 to fixedly sandwich the cord-like, elongated reinforcement members 35 between the elongated base sheet 20 and folded edge 28 and wherein the stretch percent of the reinforced stretch film 10 is increased over the stretch percent of the elongated base sheet 20 of plastic stretch film.
In one embodiment of the instant invention, the plurality of cord-like, elongated reinforcement members 35 are a randomly compressed flat, narrow plastic film strips 32 and spaced from one another and parallel. In another embodiment of the instant invention, the base sheet 20 is uncovered in the elongated spaces 52 between the parallel, elongated reinforcement strips 50 defined by the narrow plastic film strip overlays 40, the folded edges 28 and the cord-like, elongated reinforcement members 35. In still another embodiment, the reinforced stretch film 10 may further comprise a plurality of glue bead lines for attaching the cord-like, reinforcement members 35 to the base sheet 20. In still another embodiment, the narrow plastic film strip overlay 40 and each of the edges 25 are attached to the cord-like, elongated reinforcement member 35 and to the elongated base sheet 20 by a bond which is a lamination bond of the plastic film strip overlays 40 and/or the folded edges 28 to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 and a static electric seal of the plastic film strip overlays 40 and/or the folded edges 28 to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20. In yet another embodiment, the stretch percent of the reinforced film 10 is increased over the stretch percent of the elongated base sheet 20 of plastic stretch film by up to 400 percent.
The above embodiments may further include a reinforced stretch film 10 further comprising a plurality of slits through the elongated base sheet 20, the reinforcement strips 50, the folded edges 28, or a combination thereof, which expand into holes when stretched making the reinforced stretch film ventilated. The above embodiments may further include pre-stretching the reinforced stretch film 10, the elongated base sheet 20, the master material 30 the reinforcement member(s) 35, the overlay(s) 40, the reinforcement strip(s) 50, or a combination thereof. Pre-stretching may be achieved by any means known in the art. In one embodiment of the above method, the pre-stretching may be achieved by passing the above materials through a device in which the level of pre-stretch is adjusted by altering the transmission ratio of two or more power transmission gears operationally associated with a first pre-stretching roller and a second pre-stretching roller, wherein the level of pre-stretch is achieved by passing the materials over the rollers while set at a desired gear ratio.
Referring to
The method of producing reinforced stretch film 10 may include a step of forming a plurality of cord-like, elongated reinforcement members 35 (See
Referring specifically to
Referring back to
A step of positioning the plurality of cord-like, elongated reinforcement members 35 to the elongated base sheet 20 may be included in the method of producing the reinforced stretch film 10. The step of positioning the reinforcement members 35 may include any steps for positioning the reinforcement members on base sheet 20. In one embodiment, this step may include attaching the plurality of cord-like, elongated reinforcement members 35 to the elongated base sheet 20, where the cord-like, elongated reinforcement members 35 may be spaced from one another and disposed substantially parallel to one another. In another embodiment, the step of positioning the plurality of cord-like, elongated reinforcement members 35 on the elongated base sheet 20 may include attaching the plurality of cord-like, elongated reinforcement members 35 to the elongated base sheet 20 via a line of adhesive beads, sonic weld, and/or a static charge.
A step of attaching the plastic film strip overlays 40 and/or the folded edges 28 to the cord-like reinforcement members 35 and base sheet 20 may be included in the method of producing the reinforced stretch film 10. This step of attaching the overlays 40 to the reinforcement members 35 and base sheet 20 may include any steps for attaching the overlays 40. In one embodiment, this step may include: a step of holding the plastic film strip overlays 40 and/or the folded edges 28 onto the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 via static electricity; a step of laminating the plastic film strip overlays 40 and/or the folded edges 28 to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20; a step of sealing the plastic film strip overlays 40 and/or the folded edges 28 to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 via a sonic welder; or combinations thereof. In one embodiment, the step of attaching the overlays 40 and/or the folded edges 28 to the reinforcement members 35 and base sheet 20 may include a combination of: a step of holding the plastic film strip overlays 40 and/or the folded edges 28 onto the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 via static electricity; a step of laminating the plastic film strip overlays 40 and/or the folded edges 28 to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20; and a step of sealing the plastic film strip overlays 40 and/or the folded edges 28 to the cord-like, elongated reinforcement members 35 and to the elongated base sheet 20 via a sonic welder.
Immediately thereafter, plastic film strip overlays 40, which also may be polyethylene or other like material, may be applied to the base sheet 20. Plastic film strip overlays 40 may be flat and narrow. In one embodiment, the plastic film strip overlays 40 may be made from linear low-density polyethylene, also known as LLDP. In one embodiment, plastic film strip overlays 40 may be similar to base plastic film strips 32, including, being cut from the same master material 30. The plastic film strip overlays 40 may be laid over to thereby cover the cord-like reinforcement members 35. The film strip overlays 40 may be on and in engagement with the elongated base sheet 20 on opposed sides of the reinforcement members 35. In one embodiment, a second idler roll 45 may be employed for such purpose and may also establish a firm interconnection between the base sheet 20, the reinforcement members 35, and the narrow film strip overlays 40. In another embodiment, one or more press rollers 47, 48 may be employed to establish a firm interconnection between the base sheet 20, the reinforcement members 35, and the narrow film strip overlays 40.
Immediately prior to, during, or immediately after the plastic film strip overlays 40, are applied to the base sheet 20 as described above, the edges 25 of the base sheet 20 are folded over in the manner described previously creating one or two folded edges 28. The folded edges 28 may be flat and narrow. The plastic film strip overlays 40 may be laid over to thereby cover the cord-like reinforcement members 35. The folded edges 28 may be on and in engagement with the elongated base sheet 20 on opposed sides of the reinforcement members 35. In one embodiment, a second idler roll 45 may be employed for such purpose and may also establish a firm interconnection between the base sheet 20, the reinforcement members 35, and the folded edges 28. In another embodiment, one or more press rollers 47, 48 may be employed to establish a firm interconnection between the base sheet 20, the reinforcement members 35, and the folded edges 28.
The reinforcement members 35, the folded edges 28 and/or the film strip overlays 40 may form any number of elongated reinforcement strips 50 on base sheet 20. In one embodiment, the reinforcement members 35, the folded edges 28 and/or the film strip overlays 40 may form three elongated reinforcement strips 50. In another embodiment, the reinforcement members 35, the folded edges 28 and/or the film strip overlays 40 may form five elongated reinforcement strips 50, as shown in the arrangement illustrated in
The above method may further include the step of passing the reinforced stretch film 10 over a device which cuts a plurality of slits through the elongated base sheet 20, the reinforcement strips 50, the folded edges 28, or a combination thereof, which expand into holes when stretched making the reinforced stretch film ventilated. The plurality of slits may be made by any device known in the art. In another embodiment, the above method may further include pre-stretching the reinforced stretch film 10, the elongated base sheet 20, the master material 30 the reinforcement member(s) 35, the overlay(s) 40, the reinforcement strip(s) 50, or a combination thereof. Pre-stretching may be achieved by any means known in the art. In one embodiment of the above method, the pre-stretching may be achieved by passing the above materials through a device in which the level of pre-stretch is adjusted by altering the transmission ratio of two or more power transmission gears operationally associated with a first pre-stretching roller and a second pre-stretching roller, wherein the level of pre-stretch is achieved by passing the materials over the rollers while set at a desired gear ratio.
The reinforced stretch film 10 may provide an increase in the stretch percent over the stretch percent of just providing elongated base sheet of plastic stretch film. In one embodiment, the reinforced stretch film may provide an increase in the stretch percent over the stretch percent of just providing elongated base sheet of plastic stretch film by up to 400 percent. In another embodiment of the present invention, the reinforced stretch film may provide an increase in the stretch percent over the stretch percent of just providing elongated base sheet of plastic stretch film by between 150 and 400 percent. In still another embodiment of the present invention, the reinforced stretch film may provide an increase in the stretch percent over the stretch percent of just providing elongated base sheet of plastic stretch film by between 250 and 400 percent. In yet another embodiment of the present invention, the reinforced stretch film may provide an increase in the stretch percent over the stretch percent of just providing elongated base sheet of plastic stretch film by between 300 and 400 percent.
Any method described herein may incorporate any design element contained within this application and any other document/application incorporated by reference herein. Any design element contained within this application may be incorporated into any embodiment contained within this application.
In describing the invention, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and the claims.
The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention. The invention illustratively discloses herein suitably may be practiced in the absence of any element which is not specifically disclosed herein.
Number | Name | Date | Kind |
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4588463 | Barber | May 1986 | A |
Number | Date | Country | |
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20170313020 A1 | Nov 2017 | US |