The present invention relates to materials, systems, and/or methods for adhering layers in the assembly of shoes, apparel, equipment, or other items. More particularly, the present invention relates to hot melt adhesive films with at least one side entirely or partially coated with adhesives that permit the film to be temporarily and moveably adhered to a surface to be bonded using the film.
The assembly of shoes, apparel, and various types of accessories or equipment made of pliable materials often involves using adhesive films. Often, these adhesive films are at least partially melted during the assembly process to enable them to flow into the layers of material, such as textiles, above and/or below the adhesive film. For example, a film may be of a type sometimes referred to as a “hot melt” that will partially melt when heated, although films known as “cold melts” are also known, and some films may be activated with pressure and/or ultrasonic energy in addition to or instead of heat. A typical process of assembly may comprise stacking a base layer material, followed by an adhesive layer, followed by a top layer to be adhered to the base layer; after stacking a heat press or other device may be used to activate the adhesive layer to bond the base layer and the top layer together. While this process is straightforward in the case of a simple design, when an item being manufactured is complicated the proper alignment of numerous elements in stacking may be exceptionally challenging. Meanwhile, because the adhesive layer, once activated, cannot be deactivated, an incorrectly stacked item must ultimately be discarded, resulting in undesirable waste.
The present invention provides materials, systems, and methods that facilitate the assembly of shoes, apparel, equipment, accessories, or any other item using sheet adhesives. A tack layer may be added to one or both sides of the adhesive layer. The tack layer may be adhesive, glue or other material that is active at temperatures different than the adhesive layer. For example, the adhesive layer may be activated to flow and form a bond at a first temperature, while the tack layer may be active to form a bond at a second temperature, the second temperature being lower than the first temperature. For example, the tack layer may be activated at room temperature, enabling it to at least lightly adhere to compatible surfaces with not additional application of heat, pressure, ultrasonic energy, etc., while the adhesive layer may be activated only by the application of additional energy. Accordingly, the tack layer may be used to temporarily position the adhesive layer before the adhesive layer is activated. The strength of the bond formed by the tack layer may be considerably less strong than the bond formed by the adhesive layer, such that the bond formed by the tack layer may be readily severed if, for example, parts being temporarily assembled are discovered to be improperly aligned prior to the activation of the adhesive layer.
A tack layer may be provided on all or part of a surface of an adhesive layer. For example, a tack layer may only partially cover a side of the adhesive layer so as to not physically or chemically interfere with the flow of the adhesive layer when the adhesive layer is activated. The tack layer may be applied in a pattern of dots, stripes, a checkerboard, etc. in order to function as a temporary adhesive while still permitting the adhesive layer to flow when activated. If desired, opposing surfaces of the adhesive layer may have different types of tack layers, for example to provide different strengths of temporary bonds or to engage different types of materials, and/or opposing surfaces of the adhesive layer may have a tack layer provided in a different pattern. Further, one or both surfaces of an adhesive layer may be rendered tacky by forming the adhesive layer mixing at least two compounds, a first compound comprising an activatable adhesive and the second compound comprising a tacky material, thereby creating a combined activatable adhesive/tack layer.
The adhesive layer may be a completely separate item in the stacking process, but the adhesive layer may also be provided as integral to another sheet material intended to be a component of the finished product. For example, a layer for inclusion in an assembled item may be provided with an adhesive layer integral to one face of the sheet. The sheet may be a woven or knit textile, a film, a synthetic material, or other sheet type material. In such an example, the face of the integral adhesive layer facing away from the sheet material may have a tack layer to permit it to be temporarily adhered to a base layer or any other layer of material in the assembly process.
The present invention also provides methods of assembling an item using an adhesive layer with at least one tack layer on at least a first surface of the adhesive layer. Such a method may comprise forming or selecting the desired pieces for assembly, temporarily assembling the pieces using the tack layer(s) to temporarily secure the pieces together, inspecting the assembly, and then activating the adhesive layer if the assembly is acceptable.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
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A variety of materials may be used as a base layer and/or a second layer. For example, woven textiles, knit textiles, foams, natural leather, synthetic leather, films, non-woven reinforcing materials, meshes, and the like may be used in accordance with the present invention. Woven and/or knit textiles may comprise any type of natural or synthetic fibers, such as polyester, nylon, cotton, etc. Foams may be PU, EVAs, phylons, or of any other type. Films may comprise PU films, TPU films, or any other type of film material. While systems and methods in accordance with the invention may be used to bond two similar or different layers of pliable sheet type materials, non-pliable or non-sheet type materials may be bonded together in a layered arrangement in accordance with the present invention.
Further, a variety of materials may be used for an adhesive layer. The material used for an adhesive layer in accordance with the present invention may be selected based, at least in part, upon the types of materials to be permanently bonded together, i.e., the base and second materials as described in the examples herein, and based, at least in part, upon the strength of bond ultimately desired between the base material and the second material. Examples of acceptable materials are often referred to as “hot melt” or “PSA” or “PSA/hot melt” adhesives, although other types of activatable adhesive materials may be used as well. Different adhesive materials may require processing at different temperatures and/or pressures, for example at 110 degrees centigrade, 115 degrees centigrade, 118 degrees centigrade, 120 degrees centigrade, 122 degrees centigrade, 125 degrees centigrade, 130 degrees centigrade, etc, potentially with the temperature controlled to varying degrees, such as to within 2 degrees. Processing times may vary based upon the type of material used for the adhesive layer, the materials used for the base layer and the second layer, the thicknesses of the various materials used, the process temperature and/or pressure, the strength of bond ultimately desired, etc. Process times may be, for example, 30 seconds, 45 seconds, etc. Pressure applied may be, for example, approximately 5.5 kilograms per square centimeter, but more or less pressure may be used. An adhesive layer may have any thickness, such as between 0.1 and 0.5 millimeters, such as 0.2 or 0.3 millimeters.
Similarly, the amount of temporary bonding strength provided by the tack layer may be varied both by the selection of the material(s) used to form the tack layer and the arrangement of that material upon the adhesive layer. A material for the tack layer may be selected to provide the desired flexibility throughout the expected life of the item and to not create marking on a base layer or second layer of an item when a layer is repositioned if such marking is not acceptable in a finished item. A tack layer may comprise a pressure sensitive adhesive (“PSA”) a glue or other adhesive that is active under conditions that do not activate the adhesive layer. Depending upon the types and configurations of materials to be temporarily bonded using a tack layer, different bonding strengths may be desired. Further, different patterns may be desired for the tack layer to permit different bonding behaviors by the adhesive layer upon ultimate activation. If an adhesive layer is provided separate from the base layer and the second layer, the adhesive layer may have two tack surfaces, one to engage the base layer and one to engage the second layer; in such an example, different materials and different patterns may be used for the different tack layers. A few examples of the potentially infinite arrangements of a tack layer are illustrated and described herein.
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Cross sections of some examples of activatable adhesives with surface tack are illustrated in
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Systems and methods of assembling layers of items in accordance with the present invention may depart from the examples illustrated and described herein. For example, various arrangements, configurations, shapes, and materials may be used. Further, steps of the methods in accordance with the present invention may be performed in orders departing from those illustrated herein.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.
This application is a continuation-in-part of U.S. patent application Ser. No. 13/545,681, filed Jul. 10, 2012, entitled “Temporarily Positionable Meltable Adhesives For Shoe And Apparel Assembly,” which is herein incorporated by reference.
Number | Date | Country | |
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Parent | 13545681 | Jul 2012 | US |
Child | 13549025 | US |