MULTILAYER INSOLE

Abstract

Multilayer insoles made of several layers of polymeric materials and used for insertion into footwear, for example, for hygienic and orthopedic purposes. Multilayer insoles having increased manufacturability, absorption properties and low cost of environmentally friendly raw materials obtained from renewable sources.

Claims

1. A multilayer insole comprising: a base configured to fit to an inside of a shoe sole; a foam layer located above the base; and a fabric layer located above the foam layer; wherein the base comprises a rigid bio-based polyurethane; wherein the foam layer comprises a foamed bio-based polyurethane; and wherein the fabric layer comprises at least one of lyocell and bio-based polyamide.

2. The multilayer insole of claim 1, further comprising a composite layer located between the base and the foam layer, wherein the composite layer comprises a bio-based thermoplastic polymer, and wherein the composite layer is configured to support an arch portion of a user's foot.

3. The multilayer insole of claim 2, wherein the bio-based thermoplastic polymer comprises wood or cellulose fibers.

4. The multilayer insole of claim 1, wherein the fabric layer comprises a mixture of at least one of lyocell and bio-based polyamide, and coal of plant origin.

5. The multilayer insole of claim 4, wherein particles of coal of plant origin are integrated into fibers of the fabric layer.

6. The multilayer insole of claim 1, wherein the base comprises at least one elastic insert made of a bio-based polymer.

7. The multilayer insole of claim 6, wherein the bio-based polymer of the at least one elastic insert is selected from a group consisting of polyurea and a thermoplastic elastomer of copolymers of polyethylene and polypropylene.

8. The multilayer insole of claim 6, wherein an inner volume of the at least one elastic insert is filled with gel.

9. The multilayer insole of claim 1, wherein the foam layer is configured to cushion a user's foot

10. The multilayer insole of claim 1, wherein the foamed bio-based polyurethane is a shape memory foam.

11. The multilayer insole of claim 1, wherein the fabric layer has a hygienic and absorbent function.

12. The multilayer insole of claim 1, wherein the bio-based polyurethane base is selected from a group consisting of bio-based polyurethanes Pearlbond ECO (also known as Lubrizol), Renuva manufactured by Dow Chemicals, JEFFADD manufactured by Huntsman, Recypol, Econykol manufactured by Mitsui Chemicals & SKC Polyurethanes Inc.

13. The multilayer insole of claim 1, wherein the shape memory foam is Bio-Pur manufactured by Amerisleep.

14. The multilayer insole of claim 1, wherein the lyocell is tencell fiber manufactured by Lenzing Gruppe or Everest.

15. The multilayer insole of claim 18, wherein the thermoplastic polymer is selected from a group consisting of bio-based thermoplastic polyurethane Ellastolan, bio-based ethylene vinyl acetate SVT manufactured by Braschem, polystyrene thermoplastic elastomer MEGOL BIO manufactured by Trinseo and thermoplastic elastomers Terraprene manufactured by FKuR Polymers GmbH and Dryflex Green manufactured by Hexpol.

16. A method of making a multilayer insole comprising the steps of: providing a base configured to fit to an inside of a shoe sole; placing a foam layer above the base and adhering the foam layer to the base; and placing a fabric layer above the foam layer and adhering the fabric layer to the foam layer; wherein the base comprises a rigid bio-based polyurethane; wherein the foam layer comprises a foamed bio-based polyurethane; and wherein the fabric layer comprises at least one of lyocell and bio-based polyamide.

17. The method of making a multilayer insole of claim 16, further comprising the step of placing a composite layer between the base and the foam layer and adhering the composite layer to the base and the foam layer, wherein the composite layer comprises a bio-based thermoplastic polymer, and wherein the composite layer is configured to support an arch portion of a user's foot.

18. The method of making a multilayer insole of claim 16, further comprising the step of placing at least one elastic insert in the base, wherein the at least one elastic insert is made of a bio-based polymer.

19. The method of making a multilayer insole of claim 16, further comprising the step of filling an inner volume of the at least one elastic insert with gel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The design of the claimed multilayer insole is explained by the following drawings:

[0050] FIG. 1 is a schematic illustration of a longitudinal cross-sectional view of the multilayer insole of the present invention.

[0051] FIG. 2 is a schematic illustration of a longitudinal cross-sectional view of the multilayer insole of the present invention in the embodiment with a joint layer.

[0052] FIG. 3 is a schematic illustration of a longitudinal cross-sectional view of the multilayer insole of the present invention in the embodiment with elastic inserts of the base.

[0053] FIG. 4 is a bottom view of the multilayer insole of the present invention in the embodiment with elastic resilient inserts of the base.

DETAILED DESCRIPTION OF THE INVENTION

[0054] The application incorporates by reference the appendices attached herewith to the application in their entirety.

[0055] In the following description, numerous details are set forth for the purpose of explanation. However, one of ordinary skill in the art will realize that the invention may be practiced without the use of these specific details.

[0056] Bio-based polymers are derived from the biomass or issued from monomers derived from the biomass and may be, at some stage in their processing into finished products, shaped by flow. Vert, Michel (2012), Terminology for biorelated polymers and applications (IUPAC Recommendations 2012), Pure and Applied Chemistry, 84 (2):377-410. To define the bio-based part of polymer there is registered standard test described in ASTM D6866-08, Standard Test Methods For Determining The Biobased Content Of Solid, Liquid, And Gaseous Samples Using Radiocarbon Analysis. The difference between bio- and not biobased materials is typically in the content of C.sup.14 isotope in the total carbon content. This is commonly used as a marker that the polymer was produced on the base of biomass, not fossils (oil or gas) and thus is considered to be more eco-friendly because it reduces the carbon footprint of the production.

[0057] The drawings schematically show preferred but not exclusive embodiments of the claimed multilayer insole, which includes a base 1, a foam layer 2, and a fabric layer 3. In additional embodiments shown in other figures, the claimed insole may also include a composite layer 4 and elastic resilient inserts 5 of the base 1.

[0058] The base 1 may be made of rigid bio-based polyurethane, with the possibility of adhering to the inner side of the sole of the shoe and is necessary to form the structure of the claimed insole and give it a stable shape. Rigid bio-based polyurethane used in the base 1 can be, for example, bio-based polyurethanes Pearlbond™ ECO (also known as Lubrizol), Elastollan® manufactured by BASF, Renuva™ manufactured by Dow Chemicals, JEFFADD® manufactured by Huntsman, Recypol® manufactured by RAMPF, Econykol™ manufactured by Mitsui Chemicals & SKC Polyurethanes Inc, and other suitable materials. In some embodiments, the bio-based polyurethane material used for the base 1 has a Shore Hardness in the range of about 80 Hs on Shore A scale to about 80 Hs on Shore D scale.

[0059] In a preferred embodiment of the claimed insole, the base 1 comprises at least one elastic insert 5, as shown in FIGS. 3 and 4, which is made of a bio-based polymer and can be adhered to the inside of the sole of the shoe. The bio-based polymer of the elastic resilient insert 5 of the base 1 may be, for example, polyurea or a thermoplastic elastomer of copolymers of polyethylene and polypropylene, and other suitable materials. The inner volume of the elastic inserts 5 of the base 1 can be filled with gel. In the embodiment shown in FIGS. 3 and 4, the insole 1 comprises two elastic inserts 5, one positioned in the frontal areal of the insole and the other positioned in the heel area of the insole. The elastic inserts 5 perform two functions. One is to absorb the strike energy when the user concentrates his or her weight on the heel and on toes. The other is to fixate the sole inside the shoe by sticking to a surface.

[0060] The multilayer insole also includes a foam layer 2 located above the base 1. The foam layer 2 is preferably made of foamed bio-based polyurethane and is designed to cushion the user's foot. In a preferred embodiment, the foamed layer 2 takes the shape of a user's foot, and the foamed bio-based polyurethane is a so-called shape memory foam. Such foamed bio-based polyurethane can be, for example, Bio-Pur® manufactured by Amerisleep. In further embodiments, a liquid two-part composite that hardens when mixed can be used to make the foam layer 2. The first part of this composite has the main part—polyol, which may be of brands Sovernol® (BASF), Sweetch (Emery), or BiOH® (Cargill). To this part such additives as dyes, fillers, surfactants (for foam density regulation) are introduced. The second part of the composition is isocyanate. In some embodiments, the foamed bio-based polyurethane material used for the foam layer 2 has a Shore Hardness in the range of about 15 Hs to about 70 Hs on Shore A scale.

[0061] The multilayer insole further includes a fabric layer 3 located above the foam layer 2 between the foam layer and the user's foot, as seen in FIGS. 1-3. The fabric layer 3 may be made with lyocell or fibers of bio-based polyamide and has a hygienic and absorbent functions. Lyocell may be, for example, Tencell™ fiber manufactured by Lenzing, and bio-based polyamide may be, for example, bio-based polyamides known as PA11 or polyamide-11, Rilsan® manufactured by Arkema, EVO® manufactured by Fulgar, or Sorona® manufactured by DuPont. In some embodiments, lyocell and/or bio-based polyamide fibers are not used alone, but instead in mixture with cotton fibers. A percentage of cotton in the mixture may be in the range of about 25% to about 75%. A higher content provides for better absorption, whereas a lower content provides for better durability. An approximate weight of the fabric layer 3 is about 0.4 to about 0.6 grams, wherein an approximate weight of the entire multilayer insole 1 is several tens of grams. The fabric layer 3 may advantageously provide the sweat absorption characteristics to the claimed multilayer insole. Furthermore, the material used for the fabric layer 3 may include one or more suitable anti-bacterial agents to provide anti-bacterial properties to the insole.

[0062] In some preferred embodiments, the fabric layer 3 is made of a mixture of lyocell or bio-based polyamide and charcoal of plant origin. The charcoal is preferably integrated into the fibers of lyocell or the bio-based polymers during their manufacture. For example, the charcoal may be integrated inside the fibers at a stage of making those fibers from a polymer melt. It may be added there in a form of fine powder, uniformly distributed with a help of twin screw extruder, and resultant melt is directed into dies to form threads. This results in the intrinsic porosity of such fibers since the carbon particles have internal free volume, so they are absorbent, or at least more absorbent than the original polymer. This provides the advantage of this material being able to absorb sweat and other moisture. Any suitable types of charcoal of plant original may be used in accordance with the invention. For example, bamboo-based charcoal is known to have both absorption and antibacterial properties and may be used for the fabric layer.

[0063] As illustrated in FIG. 2, the insole 1 may also include a composite layer 4 that is located between the base 1 and the foam layer 2. The composite layer 4 is preferably made of a bio-based thermoplastic polymer. Suitable bio-based thermoplastic polymers may be, for example, bio-based thermoplastic polyurethane Ellastolan® manufactured by BASF, bio-based ethylene vinyl acetate SVT manufactured by Braskem, polystyrene thermoplastic elastomer Megol™ Bio manufactured by Trinseo, thermoplastic elastomer Terraprene® manufactured by FKuR Polymers GmbH, and Dryflex Green manufactured by Hexpol, as well as other suitable materials. In some embodiments, the composite layer 4 is located at least under the arch of the wearer's foot.

[0064] The composition of the bio-based thermoplastic polymer of the composite layer 4 may include wood or cellulose fibers. Any known suitable wood or cellulose fibers may be used. The advantages of adding wood or cellulose fibers to the composition of the composite layer 4 include making the layer stiffer, more resistant to dynamic loads and more eco-friendly.

[0065] The layers of the claimed multilayer insole can be bonded to each other with an adhesive, can be sewn or connected by soldering, or other similar method. For example, an acrylic adhesive may be used to provide sufficient adhesion between the composite layer 4 and the foam layer 2 to avoid their disintegration. Any other suitable types of adhesive may be used as well.

[0066] The present inventors discovered that insoles that contain TPU make a crackling sound when used with some types of shoes. This problem is caused by the “sticking” of TPU arch surface to inner surfaces of shoe, in other words, TPU can be too rubbery. To solve this problem, the present inventors developed a surface texture that assists in decreasing the contact between the show and the sole surface. In certain embodiments, the surface texture includes parts having different rigidity.

[0067] In certain embodiments, the surface is made of materials that are textured.

[0068] The claimed multilayer insole is used as follows. First, the claimed multilayer insole is placed in the shoe so that the base 1 is adjacent to the inner side of the sole of the shoe and extends over its entire area, and the fabric layer 3 is the uppermost location of the layer of the claimed insole. In an embodiment of the claimed multilayer insole with the elastic resilient inserts 5 of the base 1, as shown in FIG. 3, their location in the above-described attachment preferably corresponds to the pad of the foot and the heel of the user. Also, in the embodiment of the claimed multilayer insole with the composite layer 4, the composite layer in the above-described attachment corresponds to the arch of the user's foot and the areas of the foot close to the arch.

[0069] After inserting the claimed insole to the shoe, the user puts on the foot of the shoe. In this case, their foot is adjacent to the fabric layer 3. When wearing a shoe with the claimed insole attached to it, the fabric layer 3 absorbs sweat and, in some embodiments, disinfects the user's foot, and the foam layer 2 absorbs the load on the sole and the claimed insole. In some embodiments, the composite layer 4 is placed in the arch of the foot and forms its anatomically correct outlines. Also, in some embodiments, the elastic inserts 5 of the base 1 further absorb the load on the sole and the claimed insole, especially during intense walking or running.

[0070] In certain embodiments, the invention includes elastic inserts within recesses in the based and/or the foam layer.

[0071] In certain embodiments, the foam layer is configured to receive the base.

[0072] In certain embodiments, the base is made of rigid materials, while the foam layer is made of flexible or softer materials.

[0073] In certain embodiments, elastic inserts are made of elastic materials that have greater elasticity than the base and foam layer.

[0074] In certain embodiments, the surface structure includes materials that help decrease the squeaking of shoes.

[0075] In certain embodiments, the surface structure includes various configurations such as anisotropic, fractal anisotropic, isotropic, and others.

[0076] In certain embodiments, the direction of the texture coincides with the direction of the insole movement during use.

[0077] In certain embodiments, line thickness of not less than 0.5 mm, and the distance between the lines of not more than 0.8 mm, and depth of not less than 1 mm is provided.

[0078] The proposed technical solution is industrially applicable, as it does not contain any actions, operations or measures that cannot be reproduced at the present stage of technical development.

[0079] Other objects of the invention and its particular features and advantages will become more apparent from consideration of the following drawings and accompanying detailed description. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

[0080] Having thus described several embodiments for practicing the inventive method, its advantages and objectives can be easily understood. Variations from the description above may and can be made by one skilled in the art without departing from the scope of the invention.

[0081] Accordingly, this invention is not to be limited by the embodiments as described, which are given by way of example only and not by way of limitation.