Patent Publication Number: US-2013232825-A1

Title: Stretchable Insole

Description:
RELATED APPLICATION 
     The present application is a non-provisional application which claims the benefit of U.S. Provisional Application No. 61/607,927 filed Mar. 7, 2012. 
    
    
     BACKGROUND 
     The art is replete with attempts at making waterproof, breathable footwear. Early attempts for making such footwear included making footwear consisting of upper materials such as leather treated to make it water resistant and soles made of rubber. Thus, some breathability was achieved. However, several problems arose with this type of footwear construction. If the upper material was to be made truly waterproof, it would lose its ability to breathe. Moreover, the connecting region between the waterproof sole and the upper became a major source of leakage as there was no effective way to make the connecting region waterproof. 
     An alternative approach to the goal of achieving comfortable waterproof footwear involved employing a waterproof insert or bootie into the shoe. This method is particularly useful in machine lasted footwear, as known in the art. This waterproof insert, if constructed of appropriate materials had the additional advantage of being permeable to water vapor so that there was no buildup of water vapor within the shoe over the time when the shoe was being worn. In the footwear art materials which are both waterproof and water vapor permeable are commonly referred to as “functional” materials. Exemplary of such a functional material is a microporous, expanded polytetrafluoroethylene membrane material available from W. L. Gore and Associates, Inc., Elkton, Md., under the tradename GORE-TEX°. Other functional materials have also been developed and are well known in the art. 
     Further approaches have included securing, by a lasting process, a waterproof, breathable liner material to the inside of the footwear upper and sealing the liner material to a waterproof gasket or insole. There have been many different attempts at providing a durable, waterproof seal or connection at the region where the liner material is joined with the waterproof gasket or insole. These attempts have resulted in varying degrees of success. 
     One problem which often results when forming such waterproof, breathable footwear is that the insertion of the liner or bootie will often result in a poor fitting shoe (i.e., a smaller fit due to the liner being inserted into the already sized shoe upper) and/or poor attachment between the liner or bootie and the shoe upper material, which results in, among other things, a less than desirable appearance of the inside of the footwear (i.e., the liner appears wrinkled or pulls away from the upper). 
     An additional problem is that because of the multiple extra layers typically needed for manufacturing an article of waterproof footwear, flexibility may be severely compromised. In other words, the typical prior art waterproof shoe is much less flexible than prior art non-waterproof footwear. 
     Thus, the search continues for waterproof breathable footwear that is both durably sealed and flexible, yet economical to manufacture. 
     DEFINITIONS 
     Stretchable Insole—An insole that may be elongated up to about 285% in the cross machine direction (cross-web) at a maximum load of about 8 lbf and about 55% in the machine direction (down-web) at a maximum load of about 21 lbf without breaking. 
     Standard Footwear Construction—Footwear made substantially in accordance with the method described in Comparative Example 1. 
     Forefoot Area 5—The area of the footwear located between the front of the footwear to the beginning of the arch. 
     Rearfoot Area 15—The area of the footwear located between the end of the arch and rear of the footwear. 
     SUMMARY OF INVENTION 
     Various constructions and methods of manufacture of waterproof footwear and booties are described herein. The waterproof footwear includes a liner material having at least a waterproof, water vapor permeable functional layer and optionally at least one textile layer. During construction, the liner material is secured to an upper material. Additionally, the waterproof footwear construction includes a stretchable insole attached to the liner. The stretchable insole may include a plurality of layers including at least one polymer layer. It may also include at least one textile layer. The strobel board is attached beneath the stretchable insole and closes the upper. Additionally, the forefoot area of the waterproof footwear exhibits a reduction in stiffness in comparison to a standard footwear construction when subjected to the Mechanical Cushioning Test. As a final step, an outer sole is secure to the footwear. 
     In an embodiment, the stretchable insole comprises at least two polymeric layers and at least one of the at least two polymeric layers comprises an adhesive adapted to adhere the liner material together by use of a seam tape, for example. The textile may comprise a nonwoven material. Additionally, the waterproof, water vapor permeable functional layer may comprise a polymeric membrane material. This polymeric membrane material may be polyurethane, polyester, polyether, polyamide, polyacrylate, copolyether ester, and copolyether amide, or microporous, expanded polytetrafluoroethylene. 
     In an embodiment, the stretchable insole includes polyurethane as the one or more polymeric layers. Additionally, the liner material includes at least one waterproof, water vapor permeable functional layer and at least one textile layer. 
     In an embodiment, the forefoot area of the waterproof footwear exhibits a reduction of stiffness of at least about 6% in comparison to a standard footwear construction. 
     In an additional embodiment, the cross-web elongation at break is at least twice the length of the down-web elongation at break, desirably at least three time the length, and even more desirably at least five times the length. 
     In yet another embodiment, the cross-web elongation at break is at least 100% the down-web elongation at break, desirably at least 150%, and even more desirably at least 200% 
     Methods for making waterproof footwear are also described herein. The method includes providing upper material, providing a liner material having at least a waterproof, water vapor permeable functional layer and an open bottom portion  210 . The method also includes securing a stretchable insole material to the open bottom portion  210  of the liner material  20  at a perimeter edge portion  90  to form a bootie and subsequently locating a strobel board underneath a stretchable insole and attaching it to the upper material. 
     In this regard, the liner material is joined together in a manner to waterproof the liner, for example, by a seam tape, which may, in embodiments, contain adhesive on both the outside surface and inside surface of the seam tape. The is allows the seam tape to waterproof the liner and bond the stretchable insole to the strobel board. It is also contemplated that other mechanisms for joining the liner, other than seam tape, may be utilized. 
     Next, a shoe last is located within the bootie to form a bottom portion of the bootie and form the upper shape of the footwear. Finally, an outsole  100  is attached to the bottom surface of the strobel board to form waterproof footwear. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view of waterproof footwear containing a stretchable insole. 
         FIG. 2  is a perspective view of waterproof footwear containing a stretchable insole. 
         FIG. 3  illustrates the attachment of the individual components of waterproof footwear to each other. 
         FIG. 4  illustrates the layers of the stretchable insole. 
         FIG. 5  illustrates the cushioning properties of waterproof footwear comprising a stretchable insole. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure relates to waterproof footwear and methods for making the same. The footwear utilizes a stretchable insole  80  rather than a traditional insole material. The flexible insole contributes to an increase in comfort and flexibility for the wearer of waterproof footwear. 
     Turning to  FIGS. 1-2 , as a preliminary matter, the waterproof footwear described herein includes a liner material  20 . It also includes a stretchable insole  80  attached to the liner material  20 . 
     Turning to  FIG. 3 , described herein is a liner material  20  having an open top portion  200  and an open bottom portion  210 . Optionally, seams may be joined together to form the liner material into the general corresponding shape of a shoe upper. Pieces of liner material can be joined together by sewing, welding, gluing, etc. When pieces of liner are sewn together, the seams can be made waterproof by sealing the seams with known sealing materials, such as seam tape  25 . A seam tape may be used such as GORE-SEAM® tape (available from W. L. Gore and Associates, Inc.). Other sealants may be applied to the seams to render them waterproof if they are not inherently waterproof due to welding or gluing. The liner material  20  includes at least one layer of material which is waterproof and water vapor permeable (i.e., a functional material), such as a breathable polymeric membrane. As used herein, “water vapor permeable” and “breathable” are used interchangeably and mean that the functional layer has a water vapor coefficient Ret of less than 200 m 2  Pa W −1 . 
     Breathable polymeric membranes may be breathable by virtue of pores in the membrane or through a solution diffusion mechanism. Breathable polymeric membranes may be selected from polyurethane, polyester, polyether, polyamide, polyacrylate, copolyether ester and copolyether amides. In an aspect of the invention the waterproof, water vapor permeable membrane is a membrane of microporous polytetrafluoroethylene. In a further aspect of the invention, the microporous polytetrafluoroethylene membrane is a membrane of expanded polytetrafluoroethylene as taught in U.S. Pat. Nos. 3,953,566 and 4,187,390, to Gore. Such membranes of expanded polytetrafluoroethylene are commercially available from W. L. Gore and Associates, Inc., Elkton, Md., under the tradename GORE-TEX® fabric. 
     The liner material contains at least the above described functional material. Optionally, it may contain at least one other material attached thereto. In this regard, the liner can include the functional material  30  and a textile material  40  laminated or otherwise joined to at least one side, and often times joined to both sides thereof. Lamination is generally carried out with the use of a discontinuous pattern of suitable adhesive. Thus, water vapor permeability is not significantly affected. The at least one other material can be a textile fabric. Textile fabrics can be woven, knit, mesh, nonwoven, felt constructions, etc. Textiles can be produced from natural fibers such as cotton, or from synthetic fibers such as polyesters, polyamides, polypropylenes, polyolefins, or blends thereof. In an aspect of the invention a textile fabric is laminated to the side of the functional material which will be in contact with the upper material. In a further aspect of the invention a textile fabric is laminated to the side of the functional material which will face the inside of the footwear. In a still further aspect of the invention, textile fabric is laminated to both sides of the functional material, thus providing a three layer liner material. 
     A stretchable insole material  80  is also described herein. The stretchable insole material may be in the shape, generally, of the bottom of a foot. However, it can take the form of numerous shapes and can include multiple pieces. 
     The insole material can be any suitable stretchable material which is capable of being secured to the bottom portion of the laminate liner material to form a bootie. The insole material can be a woven or nonwoven material; or EVA or other polymer foam materials. For example, the first insole material can be polyester, nylon, polyacrylic, polyolefin, polyurethane, polyvinyl, cotton, acetate, rayon, olefin, acrylic, wool, spandex, metallic, etc. 
     A film is included as part of the stretchable insole. The film is desirably an extruded film, PVC, rubbers, neoprene, polyurethane or any other film capable of being stretched in the machine (down-web) and transverse (cross-web) directions to impart flexibility in the insole. In an embodiment, as seen on  FIG. 4 , the stretchable insole includes at least one polymeric layer  510  and at least one textile  505 , whose relative positions may be interchangeable, or alternatively at least two polymeric layers  510 ,  515  and at least one textile  505 . It is also contemplated that the stretchable insole  80  may include multiple textiles and polymeric layers. 
     The stretchable insole  80  can be secured to the liner material by any suitable means. For example, the stretchable insole can be secured to the liner material by stitching, stapling, ultra sonic welding, etc., with stitching being preferred. Upon securing the stretchable insole to the liner material, a bootie is obtained which is formed to be capable of accepting a wearer&#39;s foot. Additionally, seam tape  25  or other mechanisms for adhesion attach the strobel board to the    
     Thereafter, the bootie can be secured to the shoe upper  10  shown in  FIG. 3 . Any suitable durable material can be used to form shoe upper such as leather or fabric. Any suitable means can be used for securing the bootie to the shoe upper. In an aspect of the invention, the open top portion  200  of the bootie is secured to a collar portion or any other suitable portion of the shoe upper by stitching. 
     Upon attaching the bootie to a shoe upper, a strobel board  50  is then located under the bottom surface of the bootie. The strobel board may be constructed of a variety of materials including but not limited to: plastics, rubbers, elastomers, polyvinylchlorides, thermoplastics, polyethylene, polypropylene, ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), and may be attached by any suitable attachment means known in the art, such as for example application of adhesive or stitching. Regardless of the type of strobel board used, the strobel board is attached by seam tape  25  or other mechanisms to the upper material  10  of the footwear (See  FIG. 1 ). 
     Upon completion of this step, outer sole is attached using conventional methods known in the art. 
     In contrast to prior art constructions, this construction has a stretchable insole within a shoe construction. This assists in advantageously providing flexibility and cushioning believed to previously be found in only standard footwear constructions. These flexibility and cushioning are further illustrated in the Examples. 
     The foregoing discussion has been presented for purposes of illustration and description. Consequently, variation, modification, and combination commensurate with the above teachings, within the skill and knowledge of the relevant art, are within the scope of the present invention, including, for example, elongation and loads beyond those described in the definition of stretchable insole. 
     It is intended that the appended claims be construed to include alternative embodiments. 
     EXAMPLES 
     Test Methods 
     Centrifuge Waterproofness Test 
     Waterproofness for each sample was determined by use of the Centrifuge test described in U.S. Pat. No. 5,329,807 assigned to W.L. Gore and Associates, Inc. and incorporated by reference herein in its entirety. The centrifuge tests were carried out for 30 minutes. 
     Flexibility Testing 
     Flexibility testing for each sample was carried out in accordance with International Sports Engineering Association&#39;s flexibility test described in the article entitled “Development and reliability quantification of a novel set-up for measuring footwear bending stiffness. 
     Mechanical Cushioning Test 
     Cushioning testing for each sample was generally carried out in accordance with the testing method described in the article entitled “Polyurethane-foam Midsoles in Running Shoes—Impact Energy and Damping”. Specific variables in the test protocol are as follows. The forefoot part of the test samples were perpendicular loaded from 20 N to 1722 N using the hydraulic testing device and the forefoot intender. The rearfoot of the test samples were perpendicular loaded from 20 N to 1255 N using the hydraulic testing device and the rearfoot intender. The used load-time-shapes were derived from biomechanical studies and simulated running at a velocity of 3.5 m/s. One cycle lasts 0.7 s. 
     Example 1 
     Waterproof footwear was made with upper material available from God Speed, DONGGUAN CITY, China, part number GS14-721 Mesh non-wicking. The upper materials were stitched together to form the upper of the waterproof footwear. Liner materials were then made. The liner materials were made of expanded polytetrafluroroethylene and a textile, part number KBHX 600A available from W.L. Gore and Associates, Inc in Elkton, Md. The liner parts were stitched together to form a partial bootie. A 0.8 mm stretchable insole material from W.L. Gore and Associates, Ink in Elkton, Md., part number GSBM001 was attached to the bottom of the partial bootie to form a bootie construction. 
     The bootie was then joined to the upper by stitching the bootie to the upper at the collar portion of the upper. 
     A single layer textile strobel board 180 GSM Vildona Strobel board available from Jinjiang Chenxu Shoes Material Trade Co. Ltd. Jinjiang City, Fujian Province, China was then stitched to the bottom of the upper to form a closed upper to form a partial footwear construction. 
     A shoe last, as known in the art, was then placed inside the partial footwear construction. 
     Finally an outsole  100  made of rubber available from Zhanhui in DONGGUAN CITY, China, part number MRS-865-1 rubber outsole was attached to the bottom of the upper by use of adhesive available from Nanpao in Huang Jiang Town, China, part number WA17 Adhesive Cement Glue. 
     The footwear construction was tested for waterproofness according to the test for waterproofness described above. The footwear construction met the waterproofness standard. 
     The footwear was then tested for flexibility according to the test for flexibility described above. Test results indicated a mean stiffness of 0.073 Nm/°. 
     The footwear was then tested for cushioning according to the Mechanical Cushioning Test described above. Test results indicated a mean stiffness of 117.0 N/mm in the forefoot area of the footwear while increasing the load from 200 N to 400 N. This indicates substantially more cushioning in this footwear containing a stretchable insole than in the comparative examples detailed below, specifically about 3% as compared to comparative Example 2 and 6% as compared to Comparative Example 1. It is believed that this is possible because of more equal load distribution due to the flexibility of the stretchable insole attached to the upper. It is also believed that because of the differing dimensions in the heel area (higher amount of standard cushioning material, e.g. EVA or PU), the impact on rearfoot cushioning is not as great, as further illustrated in  FIG. 5 . 
     Comparative Example 1 
     Non-waterproof footwear was made with upper material available from God Speed, DONGGUAN CITY, China, part number GS14-721 Mesh non-wicking. The upper materials were stitched together to form the upper of the non-waterproof footwear. Liner materials were then made. The liner materials were made of textile, part number GS11-C+2 mm Foam+20 gram Tricot available from Godspeed Industrial Group, Dongguan, China. The liner is stitched together. 
     The liner was then joined to the upper by stitching the liner to the upper at the collar portion of the upper. 
     A strobel board 180 grams/m̂2 Vidona Strobel available from Jinjiang Chenxu Shoes Material Trade Co., Ltd, Jinjiang City, Fujian Province, China was then stitched to the bottom of the upper to form a closed upper A shoe last, as known in the art, was then placed inside the partial footwear construction. 
     Finally an outsole made of rubber available from Zhanhui in DONGGUAN CITY, China, part number MRS-865-1 rubber outsole was attached to the bottom of the upper by use of adhesive available from Nanpao in Huang Jiang Town, China, part number WA17 Adhesive Cement Glue. 
     The footwear was tested for flexibility according to the test for flexibility described above. Test results indicated a mean stiffness of 0.067 Nm/°. 
     The footwear was then tested for cushioning according to the Mechanical Cushioning Test described above. Test results indicated a mean stiffness of 124 Nm/° in the forefoot area of the footwear. 
     Comparative Example 2 
     Waterproof footwear having a non-stretchable insole were made substantially in accordance with the teachings of U.S. Pat. No. 6,935,053 assigned to W.L. Gore and Associates, Inc and hereby incorporated by reference in its entirety. The footwear was tested for flexibility according to the test for flexibility described above. Test results indicated a mean stiffness of 0.083 Nm/°. 
     The footwear was then tested for cushioning according to the Mechanical Cushioning Test described above. Test results indicated a mean stiffness of 121.2 Nm/° in the forefoot area of the footwear. 
     Tensile Test Method 
     A 4 inch (10.16 cm) length and 0.5 inch (1.27 cm) wide sample is firmly held in place between two air clamps which have previously been set at a gap length of 2 inches (5.08 cm). Using an Instron® 5500R material test equipment available from Instron® (825 University Avenue, Norwood, Mass. 02062-2642, U.S.A.) fitted with a 2001b (90.8 kg) load cell and at a room temperature of 73F (22.7° C.), the samples were tensile tested at a rate of 10 inch/min (25.4 cm/min) and the applied load and % strain recorded until the textile is fractured. The maximum load and elongation at break are noted for both down-web (also known as machine direction) and cross-web (also known as transverse direction) samples. 
     Example A 
     The stretchable insole, as a barrier layer, was manufactured substantially in accordance with the stretchable insole in above Example 1, except it exhibited a thickness of 6 mil. It was tested in accordance with the Tensile Test method described above. 
     Example B 
     The stretchable insole was manufactured substantially in accordance with the stretchable insole in above Example 1, except it includes two layers, a 3 mil barrier layer, and a 3 mil adhesive layer. It was tested in accordance with the Tensile Test method described above. 
     Comparative Example A 
     The insole was manufactured substantially in accordance with the non-stretchable insole in Comparative Example 2 above. It was tested in accordance with the Tensile Test method described above. 
     Test Results 
     Example A 
     Down-Web 
     Maximum load=22.064 lbf (10.017 kg) 
     Elongation at Break=70.8% 
     Cross-Web 
     Maximum load=8.766 lbf (3.979 kg) 
     Elongation at Break=197.5% 
     Example B 
     Down-Web 
     Maximum load=20.673 lbf (9.385 kg) 
     Elongation at Break=54.2% 
     Cross-Web 
     Maximum load=7.958 lbf (3.612 kg) 
     Elongation at Break=281.7% 
     Comparative Example A 
     Down-Web 
     Maximum load=13.253 lbf (6.016 kg) 
     Elongation at Break=50% 
     Cross-Web 
     Maximum load=9.967 lbf (4.525 kg)
 
Elongation at Break=91.7%