Background

[0001] An inner sole of a shoe, boot or other footwear is where the foot rests. Inner soles, also referred to as sock liners, provide comfort, warmth and support to the feet of a user. Inner soles were traditionally made of leather or rubber but now are typically made of open or closed cell synthetic foams. The use of synthetic foam allows for molding of the inner sole to provide support to the user's foot by, for example, providing arch support or heel contours.

[0002] Molding also allows the creation of sipes in the inner sole. Sipes are grooves or channels. When provided for in an inner sole, the sipe or sipes are typically located on the underside of the inner sole at the ball of the foot with the goal of allowing for greater flexibility of the inner sole and, therefore, greater comfort for the user. However, current methods of manufacturing sipes in inner soles actually result in reduced flexibility at the sipe defeating the intended goal for greater flexibility.

Summary of the Invention

[0003] The present invention is directed towards a new and non-obvious method of manufacture of the sipe(s) in inner soles. Traditionally, sipes are made in inner soles through a molding process using heat and pressure. The goal of inner sole

manufacturers is to provide maximum product output at minimal cost. Thus, speed of manufacture is an important concern to inner sole manufacturers with faster production resulting in lower production cost

[0004] The present inventors have discovered that when molding sipes in inner soles, current manufacturing methods actually result in reduced flexibility at the sipe location defeating the goal of providing increased flexibility for the user. Thus, instead of providing greater comfort for the user, current manufacturing processes actually result in the manufacture of inner soles that can decrease user comfort. [0006] The reason current manufacturing process result in reduced flexibility at the sipe location has to do with the speed at which the inner soles are produced. In order to produce inner soles at high speed, the foam is compressed quickly and under external accelerated pressure in a heated mold. The compression caused by these methods at the location of the molding bars that create the sipes in the inner sole results in the compression of the foam at that location thereby creating an area of dense foam at the sipe location. The present inventors have found that the increased density of foam at this location actually reduces flexibility of the inner sole at the sipe location.

[0006] The present inventors have solved the industry problem of producing inner soles with denser foam at the sipe location by producing inner soles in a counterintuitive manner. While not being limited to theory, the present inventors have found that if inner soles are molded slowly, rather than quickly as is the industry standard, the foam at the sipe location has time to move or flow laterally from the sipe location, thereby greatly reducing or eliminating compression of the foam at that location. In other words, this method of inner sole production was found to produce sipes without compressing the foam at the sipe location or with minimal compression of the foam at the sipe location. Thus, the method of inner sole production of the present invention, wherein the inner soies are molded slowly in sharp contrast to the prior art methods, produces inner soles with sipes that actually do provide greater flexibility for the user at the sipe location of the inner sole.

[0007] In an embodiment of the present invention, the foam at the location of the sipe (i.e., above the sipe) after the molding of the sipe is no more than 5%, 10%, 20% or 25% denser that the density of the foam prior to molding of the inner sole.

[0008] Thus, the present invention is a method of manufacture of inner soles with

improved sipes, the method comprising: providing; i) a mold comprising a top mold plate and a bottom mold plate with each of the top and bottom mold plates having molding surfaces that face each other during the molding process and one of said top or bottom mold plates having one or more raised sipe elements positioned for the creation of one or more sipes on an inner sole, said mold plates capable of being heated at the molding surface, and ii) a moldable foam sheet; heating the molding surfaces to a temperature suitable for molding the moldabte foam sheet; placing the moldable foam sheet between the top and bottom mold plates; resting the top moid plate on the moldable foam sheet so that the moJdable foam sheet substantially contacts the top mold plate and the bottom mold plate and with no external accelerated pressure applied to the top or bottom mold plates; molding the moldable foam sheet for approximately 135 - 205 seconds until the si pes form in the moldable foam sheet to create a molded foam sheet with at least one sipe per inner sole; removing the moldable foam sheet with at least one sipe per inner sole from the mold and, optionally, trimming the molded foam sheet.

[0009] Further details of the method of manufacture of the present invention are detailed herein.

Brief Description of Figures

[0010] Figure 1 A&B show A) the bottom surface of the top inner sole mold and B) the top surface of the bottom inner sole mold.

[0011] Figure 2 shows a top view of the bottom inner sole mold.

[0012] Figure 3 shows a sheet of foam sandwiched between and making substantial contact with the bottom and top molds.

[0013] Figure 4 shows the placement of the top moid onto the bottom mold.

[0014] Figure 5 is a close-up view of the sipe bars of the bottom mold.

[0015] Figure 6 shows a bottom view of a foam sheet after molding by the method of manufacture of the present invention.

[0016] Figure 7 shows a bottom view of the inner soles of the present invention after trimming.

[0017] Figure 8 shows an inner sole made by the method of manufacture of the present invention flexed at the sipe locations.

Detailed Description of the Invention

[0018] Various embodiments of the invention will now be explained in greater detail. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. Any discussion of certain embodiments or features serves to illustrate certain exemplary aspects of the invention. The invention is not limited to the

embodiments specifically discussed herein.

[0019] Unless otherwise indicated, all numbers such as those expressing temperatures, weight percent, concentrations, time periods, dimensions, and values for certain parameters used in the specification and claims are to be understood as being modified in all instances by the term "about," unless clearly stated otherwise. It should also be understood that the precise numerical values and ranges used in the specification and claims form additional embodiments of the invention.

[0020] The present invention may be understood more readily by reference to the

following detailed description of the invention taken in connection with the accompanying drawing figures, which form a part of this disclosure. K is to be understood that this invention is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed invention. Accordingly, unless explicitly stated otherwise, the descriptions relate to one or more embodiments and should not be construed to limit the embodiments as a whole. This is true regardless of whether or not the disclosure states that a feature is related to "a," "the," "one," "one or more," "some," or "various" embodiments. Instead, the proper scope of the embodiments is defined by the appended claims. Further, stating that a feature may exist indicates that the feature may exist in one or more embodiments.

[0021] Also, as used in the specification including the appended claims, the singular forms "a," "an," and "the" include the plural, and reference to a particular numerical value includes at least that particular value, unless the context dearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value and all values between, regardless as to if they have been explicitly identified. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment

[0022] In this disclosure, the terms "include," "including," "comprise," "comprising," "contain," "containing," "have," and "having" when used after a set or a system, mean an open inclusion and do not exclude addition of other, non-enumerated, members to the set or to the system. Further, unless stated otherwise or deducted otherwise from the context, the conjunction "or," if used, is not exclusive, but is instead inclusive to mean and/or. Moreover, if these terms are used, a subset of a set may include one or more than one, up to and including all members of the set.

[0023] The phrase "consisting of excludes any element, step or ingredient not specified in the claim. The phrase "consisting essentially of limits the scope of a claim to the specified materials or steps and materials or steps that do not materially affect the basic and novel characteristics of the claimed invention. It is clear from this specification which elements do and do not materially affect the basic and novel characteristics of the claimed invention. Further, any elements recited in a dependent claim, even though further limiting, are not considered to be essential to the elements recited in the identified independent claim. The present disclosure contemplates embodiments of the invention compositions and methods corresponding to the scope of each of these phrases. Thus, a composition or method comprising recited elements or steps contemplates particular embodiments in which the composition or method consists essentially of or consists of those elements or steps.

[0024] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods and materials are now described.

[0025] Methods of manufacture of the present invention of inner soles with sipes are evident from the description herein and are specifically included as part of the disclosed invention.

[0026] Now, the invention will be described in view of the appended drawings. One of ordinary skill in the art will understand that the method of manufacture of the present invention may be altered for specific purposes without deviating from the character encompassed by this invention based on the teachings of this specification and without undue experimentation.

[0027] Figure 1 A shows a perspective view of the bottom of a top mold 10 of the present invention. The top mold is flipped over so detail of the molding surface can be seen. Heal contours 12 are evident. Also shown are alignment pin receptacles 16 and fine alignment pin receptacles 18.

[0028] Figure 1 B shows a perspective view of the top surface of the bottom mold. 20 of the present invention. Visible in this view are the heal contours 22 that correspond to the heal contours of the top mold, sipe bars 24, alignment pins 26 and fine alignment pins 28

[0029] Figure 2 shows a top view of the bottom mold 20 of the present invention. Visible in this view are the heal contours 22, sipe bars 24, alignment pins 26 and fine alignment pins 28. The top surface of the bottom mold may also be designed to mold other things than sipe bars into the inner sole. For example, the manufacturer's name and/or trademark may be molded into the surface of the inner sole for identification. The present invention is not limited by the number of sipes per inner sole nor In the arrangement of sipes on the inner soles. In a preferred embodiment, number of sipe bars may be from 1 to about 10 per inner sole or 1 to 5 per inner sole. In a preferred embodiment, the sipes are contemplated to extend across the width of the inner sole. In other embodiments, the sipes may not extend continuously across the inner sole and/or may have areas of non-molded foam between two co-linear or substantially co-linear sections of a sipe. Further, sipes may extend only part of the width of the inner sole and sipes may or may not align with sipes that extend only part of the width of the inner sole from the other side of the inner sole. In other words, sipes that extend from one edge of an inner sole may be discontinuous with sipes that extend from the opposite side of the inner sole. In yet another embodiment, three rows of sipes can be molded into an inner sole of the present invention. For example, sipes may extend about 1/3 of the distance from both sides of the inner sole and discontinuous sipes may be positioned co-linear or approximately co-linear with the sipe extending from the inner sole edges. In a preferred embodiment, the sipes of the present invention run substantially from side-to-side of the inner sole and not from heal-to-toe. [0030] Figure 3 shows the foam sheet 30 of the inner sole sandwiched between the top 10 and bottom molds 20. During the molding process, the foam sheet makes contact with or makes substantial contact with the bottom surface of the top mold and the top surface of the bottom mold at least for the area of the mold associated with the inner sole being made. The tolerance of the mold in areas that do not result in the molding of the foam sheet into the inner sole of the present invention do not need to be as tight and, therefore, the foam sheet may or may not make substantial contact with the molds in these areas.

[0031] The inner sole of the present invention is molded slowly to permit the softened or melted foam time to flow laterally from the area of the sipe bars. This is in sharp contrast to prior art methods where inner soles are molded quickly to increase production speed and lower production cost However, the present inventors have found that the prior art methods result in foam being compressed at the location of the sipe creating a denser foam at the sipe location. The denser foam actually results in decreased flexibility at the location of the sipe.

[0032] The actual molding process of the present invention, i.e., the dwell time, takes from approximately 135 to approximately 205 seconds. One of ordinary skill in the art will be able to adjust the dwell time of the method of the present invention based on the type of foam used and the temperature of the molding surfaces based on the teachings of this specification without undue experimentation.

[0033] In contrast to the present invention, the molding processes used by prior art methods take only a few seconds. The high speed of molding in the prior art methods is achieved by applying accelerated pressure to the molds. Accelerated pressure can be applied by any means that helps to force the two molds together. The means for generating accelerated pressure can be manual; for example pressure applied by a user pushing down on the mold or a lever or other device or by clamping the mokte together. The means for generating accelerated pressure can also be by mechanical means such as with hydraulic presses.

[0034] In sharp contrast to the methods of manufacture of the prior art, no accelerated pressure is used in the manufacture of the inner soles of the present invention. The only pressure used in the present invention is the weight of the top molding plate being rested on the bottom mold while sandwiching the foam sheet between the two molds. In one embodiment of the present invention, each (top or bottom) molding plate weights about 22 lbs. each (or about 44 lbs. for the pair of top/bottom molding plates). (Each molding plate may weigh from about 20 to about 24 lbs. or about 21 to about 23 lbs. If the molding plates are designed to mold more than one pair of inner soles at the same time, each molding plate (top or bottom plate) weighs about 22 lbs. per inner sole pair. Since the inner soles of the present invention are molded without accelerated pressure, the weight of the mold used on the top of the foam sheet is important Therefore, the weight of the bottom mold may vary from the ranges given above without adversely affecting the methods of the present invention.

[0036] In another embodiment of the present invention, devices may be used to ensure that the inner soles of the present invention are not molded too quickly. For example, springs, slow-release hydraulics or other means known to one of skill in the art may be used to ensure that the molding process is slow enough to ensure that the si pes made by the methods of the present invention are made with the characteristics described in the next paragraph and/or to ensure consistency in manufacturing. Any such means may be subject to automatic control by, for example, computer.

[0038] The method of the present invention results in an inner sole with sipes, wherein the density of the foam at the sipe after molding ^' » no more than 5%, 10%, 20% or 25% denser than the density of the foam sheet prior to the molding of the inner sole.

[0037] The method of the present invention, in a preferred embodiment, produces sipes that are positioned in the mold such that the sipes, when molded into the inner sole, are located at or near the ball of the foot when the inner sole is used in footwear.

[0038] In the present invention, the molding surfaces of the top and bottom molds are heated from approximately 150 °C to approximately 190 °C. In the present invention, the molding surfaces are heated to approximately 170 °C. The actual temperature used is dependent upon the type of foam used and the desire to mold the sipes slowly, as described above. In a preferred embodiment, the molds are heated internally with, preferably, electrical heating elements. The heating of the molds may be controlled electronically.

[0039] The type of foam used can be selected from open cell or closed cell foam.

Representative types of open cell foam are polyurethane, foam rubber, silicon, polyether, polyester, etc. Representative types of closed cell foam are polyethylene, neoprene, cross-linked polyethylene, polystyrene and polypropylene, etc. However, any foam suitable for the use as an inner sole is contemplated to be used with the present invention. Various foams are known to one of ordinary skill in the art. One of skill in the art, with the teachings of this specification, will be able to select a suitable foam sheet for the manufacture of inner soles with the methods of this invention, without undue experimentation. Preferred foam for the present invention is open cell polyurethane. The density of the foam may range from about 2 lb/ft ³ to about 50 lb/ft ³ , about 2 lb/ft ³ - about

[0040] The foam sheets of the present invention may be covered on at least one side with a cloth material. The foam sheets of the present invention may include, for example, additives to reduce foot odor, such as activated charcoal. The foam sheets of the present invention may be made from more than one type of foam. For example, the foam sheet may be made of a moldable layer and a non-mo!dable layer, the non- moldabte layer suitable of providing impact absorbance. Further, the foam sheets of the present invention may be made from more than one type of foam with, for example, an impact absorbent foam being positioned at or near the heal and a moldable foam being positioned at or near the ball of the foot The inner soles of the present invention may also comprise "memory foam" where suitable.

[0041] The foam sheets used in the present invention may range in thickness from

approximately 2 mm - 10 mm; 2 mm - 6 mm; 3 mm - 5 mm or 4 mm thick prior to molding. The method of the present invention produces sipes that are no thicker than 1 mm less than the thickness of the foam sheet prior to molding. For example, if the foam sheet is 4 mm thick, the sipes molded into the foam sheet by the method of the present invention are no more than 3 mm thick.

[0042] Figure 4 shows the top mold being positioned over the bottom mold. The

alignment pins 26 and fine alignment pins 28 of the bottom mold are shown. The alignment pins 26 of the bottom mold are positioned in receptacles on the top mold 16. The fine alignment pins of the bottom mold are also positioned in receptacles on the top mold (see, Figure 1, no. 18).

[0043] Figure 5 shows a close-up view of the sipes 24 and a fine alignment pin 28 on the bottom mold. [0044] Figure 6 shows the bottom view of a foam sheet 30 molded with the method of the present invention. The molded sipes 34 are clearly visible. Figure 7 shows a bottom view of the inner soles 32 molded with the method of the present invention after trimming off the excess foam sheet.

[0046] Figure 8 shows an inner sole 32 molded with the method of the present invention being flexed at the location of the sipes 34.