Patent Application
20050181164
A floor, stair step, ladder rung, or a sporting device, such as a skateboard or scooter, and other structures and devices presenting a substrate upon which a user steps, may be improved in the friction provided to the user's foot or shoe by applying a grip tape over the substrate. The tape is typically provided with a friction-enhanced upper surface, for example, by a layer of grit that covers the upper surface of the tape.
The tape typically includes a lower surface coated with an adhesive to attach the tape to the substrate, and it is desirable that the tape adhere uniformly and conformably to the substrate. Sometimes, however, uniform and conformal adherence of the tape to the substrate is not achieved. This tends to happen particularly in the case where the substrate is not a simple flat plane, but is curved or angled in one or more directions, with either a simple linear curve or angle or a more complex shape, and where the area to be covered is relatively large, that is, several inches in width and/or length. The tape, as it is lowered onto the substrate and pressed into place, may trap air bubbles between the tape and the substrate.
At the location of each air bubble, the tape is typically not adhered to the substrate and is raised in a hemispherical shape. Such conditions, when the user's shoe is pressed onto and slided along or across the tape and/or moved rotationally with respect to the tape, tend to overcome the tensile strength of the tape in the area adjacent the bubble and to cause the tape to fail by tearing.
When the tape fails, a portion of the tape may tear completely away or become deformed to the point that the tape in that area provides no improvement in traction. The torn tape, and the air bubbles, even when not torn, create a non-uniform, undesirable surface, which in addition to the degradation in traction performance, may obscure a design, wording, or other graphic material printed on the tape. The air bubbles may be removed by popping each bubble, but this is time-consuming and may tear the tape because of the pressure of the air bubble on the tape.
A grip tape is provided that can be applied to a substrate without substantially entrapping air bubbles between the tape and the substrate. The grip tape may be made up of a sheet of film with a layer of grit material fixed on one side of the sheet and an adhesive layer on the opposite side of the sheet. The adhesive layer, grit layer, and sheet may be provided with a plurality of perforations extending therethrough. These perforations may be distributed over the area of the sheet surfaces. These perforations each define a cross-sectional area, and in combination the plurality of perforations defines a cumulative area, which typically is no more than about 1% of the sheet surface area over which the perforations are distributed.
The film sheet of the grip tape may be substantially comprised of a thermoplastic material, and may be formed with two plies for improved tensile strength. The perforations are typically regularly distributed over the tape and are spaced apart and provided with a sufficient cross-sectional area to allow sufficient fluid passage therethrough to substantially prevent the entrapping of air bubbles between the tape and the substrate.
A method for making the grip tape may include providing a length of film, applying an adhesive layer to one side of the film, applying a layer of grit to the other side of the film, and perforating the film, adhesive layer, and grit layer with a plurality of pinholes distributed over the length and width of the film. The perforation may be carried out by running the tape through rollers, using a die, or other suitable methods.
As shown in
Film sheet 12 includes a first or upper surface 18 and a second or lower surface 20 opposite to and coextensive with the first surface. The surfaces have a width W and a length L defining an area A (
The tape also includes a layer 22 of grit material 24 fixed on upper surface 18, typically by a binder material 26 that has been spread over surface 20. Grit material 24 may be further fixed in place by an adhesive layer 28 (shown partially cutaway in
Typically grit material 24 includes one or more of crushed glass particles, silicon carbide, or aluminum oxide or other suitable mineral-based or other type of grit material. Typically the grit material is screened or otherwise selected to a mesh size of between about 60 and about 100. Preferably a hard material, such as silicon carbide is used, although materials having a greater or lesser hardness and greater or lesser mesh size may be selected, depending on the desired performance characteristics for the tape's expected application. Typically the grit material or other friction-enhancing feature of the tape extends substantially over the entire upper surface of film sheet 12, but alternatively the friction-enhancing may cover only a portion of the upper surface and may be arranged in any shape or pattern.
The tape also includes an adhesive layer 30 coated or otherwise affixed on lower surface 20 of film sheet 12. Layer 30 is preferably a pressure-sensitive adhesive but alternatively may be a moisture activated or other type of adhesive. Furthermore, adhesive layer 30 may be left off of tape 10, and the tape attached to a substrate by application of an adhesive at the time of use to either the tape of the substrate, or by other means of affixing the tape to the substrate. Typically, adhesive layer 30 covers substantially the entire lower surface 20 of sheet 12, but alternatively may cover only a portion depending on the desired characteristic of the tape.
As shown in
Film sheet 12 is preferably provided in a planar, uniform, continuous sheet, and grit layer 22 and adhesive layer 30 are fixed on the opposing surfaces of film sheet 12 also in a planar, uniform, continuous manner, although other constructions may alternatively be used. Tape 10 thus preferably is initially provided in a planar, uniform, continuous format, and then is processed to add a plurality of perforations, such as pinholes 34 (See
Pinholes 34 are typically circular, as viewed from above in
Pinholes 34 typically are of a uniform size and shape, but may be produced in varying shapes and sizes. In any case of size, shape, and distribution, the pinholes will define a cumulative area, i.e., the sum of the cross-sectional areas of the pinholes, for the area of the sheet surface over which the pinholes are distributed. Typically the cumulative area of the pinholes is between about 0.04% and about 1.0% of the sheet surface area over which the pinholes are distributed. The pinholes are preferably sized, shaped, and distributed to provide sheet 12 with sufficient fluid passage therethrough to substantially prevent the entrapping of air bubbles between the tape and the substrate as the tape is lowered onto and adhered to the substrate.
A method for making an embodiment of the grip tape is shown in
As illustrated in
A roll 60 of release paper 32 may be applied over the adhesive side of film sheet 12 and typically is pressed onto the adhesive by a pass through a pair of pinch rollers 62. The assembled film sheet 12, adhesive layer 30, and release paper 32 may be rolled up in a roll 64. The pinch rollers provide sufficient adherence of the release paper to the adhesive so that it remains in place during subsequent processing and shipping of the tape, until the user is ready to apply the tape to the substrate. Other methods may be used of applying the release paper.
As illustrated in
Grit 24 may then be applied to the film sheet, for example by an electrostatic application wherein the film sheet passes in close proximity over a tray or other carrier 72 of grit 24 and static electricity produced by an electrode 74 or other device causes the grit pieces to be driven upwards and embedded in the layer of binder 70. Typically at this point most pieces of grit are partially embedded in binder 70, which is still wet, and a portion of each grit piece protrudes out of the binder. The binder may then be at least partially cured on film sheet 12, for example by drying the binder in an environment 76 preferably heated to between about 100° C. and about 110° C. Other methods may be used to apply the binder and grit to the tape, which may or may not make use of the curing step.
The grit pieces and binder on film sheet 12 may be overlaid with a coating of an adhesive 78 by passing the film sheet through a pair of opposed rollers 80. The upper one of rollers 80 preferably draws adhesive 78 from a tub 82 and applies it over the grit pieces and binder on upper surface 18 of film sheet 12. Adhesive 78 may then be cured on film sheet 12, for example by drying the adhesive in an environment 84 preferably heated to between about 100° C. and about 110° C. Other methods may be used to apply adhesive 78 to the tape, which may or may not make use of the curing step. The assembled tape may then be rolled up in a roll 86 for further processing.
As shown in
Another method of perforating the tape is shown in
The subject matter described herein includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions and/or properties disclosed herein. Similarly, where the claims recite “a” or “a first” element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. It is believed that the following claims particularly point out certain combinations and subcombinations that are directed to one of the disclosed embodiments and are novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the present disclosure.
