FOOTWEAR AND THE MANUFACTURE THEREOF

Abstract: An item of footwear such as a shoe comprises an outer sole (16) which may include an intermediate mid sole (17), an upper (12) having an insole (20) with a cavity (18) between the outer sole (16) or mid sole (17) and insole (20). The cavity (18) receives injected into it cushioning resilient foam material (19) which may extend into a heel portion (15) of or to the outer sole (16) of a multi-layer sole and heel unit (14). In the method of manufacture and after the assembly of the shoe with the empty cavity (18), the resilient material (19) is subsequently injected into the cavity (18) e.g. through a small bore (22) in the outer sole (16) or elsewhere. Vent holes (24, 26) enable air to escape from the cavity (18) to ensure full and intimate filling of the cavity (18) with the foam material (19). The upper (12) may be retained on a last during injection to maintain a desired profile of the insole (20). Quantity and/or pressure of the injected material may be varied for obtaining different degrees of cushioning.

Description: Title: Footwear and the Manufacture thereof The present invention relates to footwear such as shoes. Some shoe designs have a cavity between the outer sole and the shoe upper which normally contains a piece of synthetic material placed in the cavity during manufacture of the shoe. Whilst providing some cushioning for the wearer, the synthetic piece does not always effectively extend throughout the outer sole such as into the heel portion of the shoe and since it is a discrete piece of material it is not possible to vary the cushioning effect in a range of shoes. The present invention seeks to provide an improved item of footwear and a method of manufacturing such an item of footwear. The present invention provides an item of footwear such as a shoe comprising an outer sole and an upper having an insole, and at least one cavity between the outer sole and insole having inserted therein by injection a resilient material which provides cushioning between the outer sole and insole. The invention also provides a method of manufacture of footwear such as a shoe comprising the assembly of securing an outer sole to an upper to provide at least one empty cavity between said outer sole and an insole of said upper, and subsequent to said assembly, injecting into said at least one cavity a resilient material to provide cushioning between the outer sole and the insole. In a preferred form of the invention the material is a synthetic material, preferably a plastics foam. The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings which are each a longitudinal section through a preferred form of shoe according to the present invention. Referring to the drawings, there is shown a shoe 10 having a shoe upper 12 of leather or synthetic material secured to a multi-layered sole and heel unit 14. The assembly has an outer sole 16 and a heel 15 of resilient, lightweight synthetic material, an intermediate layer or mid sole 17 which may or may not be integral w h the outer sole 16 and heel 15, and an insole 20. In the illustrated embodiments the intermediate layer 17 has a cavity 18 extending the full length of the shoe from the toe portion to the heel portion between the outer sole 16 (or mid sole 17) and the insole 20. Normally, during manufacture of the shoe a discrete piece or pieces of a resilient material such as a synthetic foam would be inserted into the cavity in order to provide some cushioning effect for the user. However, in the preferred process according to the present invention, during manufacture of the shoe the cavity 18 is left empty. Then, once assembly of the shoe has been completed, ie after the outer sole 16 and heel unit 15 is attached to the upper 12, a synthetic foam material 19 is subsequently injected under pressure into the cavity 18 to fill the whole of the cavity from the toe portion to the heel portion of the shoe. The synthetic material is conveniently injected through a small bore 22 which extends through the outer sole 16. Air which is trapped in the cavity 18 is allowed to escape through breather holes 24 and 26 to enable the synthetic material to fully and intimately fill the whole of the cavity. The cavity 18 and foam material 19 are shown extending into a recess 150 in the heel 15 which recess is further shown of extended depth in Figure 2. The shoe is conveniently retained on a last or other support for the insole 20 during injection, the last serving to maintain the desired profile of the insole of the shoe. The pressure injection oζ for example, a reactive, high resilience chemical foam into the cavity 18 is particularly suited to Goodyear welted footwear. It is also suited to other construction methods of manufacture where units (i.e. the combined heel and sole) have a cavity in the fore part waist and heel as shown. Variation of the quantity of synthetic material injected and/or the pressure at which the material is injected allows the cushioning effect of the material to be varied easily, enabling a range of footwear providing different cushioning to be produced. By injecting a synthetic foam material one can ensure that the whole of the cavity 18 is filled by the material to provide a full cushioning effect between the outer sole and the insole. Injection can be effected using, for example, specialist low pressure metering apparatus. In trials, a mixture of base resin and hardening agent (typically Diphenylmethane 4,4' Di-isocyanate) at a ratio of 3:1 was injected into the cavity 18 of a shoe at ambient temperature. Table I below sets out the details of the quantities used to inject five different shoes, all of which provided a noticeable improvement in comfort in the footwear. Ideally, a foam density of 0.2 - 0.3g/cm is employed. The mix used also resulted in a "skin" forming on the outside of the injected material, this skin restricting water penetration into the body of the foam material. TABLE I Injected Injection Material Rate Injection Weight (g) (g sec) Time 60 14.5 4.2 65 14.5 4.5 70 14.5 4.8 75 14.5 5.2 80 14.5 5.5 In a further form of the invention, the sole 14 is a single layer sole and the cavity or cavities 18 are formed in the single layer sole. Although the bore 22 is described as being provided in the outer sole 16, it will be appreciated that the synthetic material can be injected into the cavity at any convenient location, for example through the shoe insole 20.

Claims: Claims 1. An item of footwear such as a shoe comprising an outer sole and an upper having an insole, and at least one cavity between the outer sole and insole having inserted therein by injection a resilient material which provides cushioning between the outer sole and insole. 2. An hem of footwear according to claim 1 wherein the resilient material is of foam texture. 3. An hem of footwear according to claim 1 or 2 wherein a heel unit or portion of or to the outer sole also receives the injected resilient material between it and the inner sole to provide cushioning between the heel unit or portion and the insole. 4. An item of footwear according to claim 3 wherein the heel unit or portion is internally recessed to receive the injected resilient material between it and the inner sole. 5. An hem of footwear such as a shoe substantially as herein described with reference to the accompanying drawings. 6. Manufacture of footwear such as a shoe comprising :- (a) the assembly of securing an outer sole to an upper to form at least one empty cavity between said outer sole and an insole of said upper, and (b) subsequent to said assembly injecting into said at least one cavity a resilient material to provide cushioning between the outer sole and the insole. 7. Manufacture of footwear according to claim 6 wherein the injection of the resihent material into said at least one cavity is such that the resihent material fully and intimately extends throughout the cavity. 8. Manufacture of footwear according to claim 6 or 7 wherein the upper is retained on a last or other support for the insole during injection of the resihent material mto said at least one cavity, the last or other support serving to maintain a desired profile of the insole. 9. Manufacture of footwear according to any of claims 6,7 or 8 wherein the quantity of the resilient material and/or the pressure at which it is injected into the said at least one cavity can be varied for readily providing a desired degree of cushioning eg in providing a range of footwear having different cushioning characteristics. 10. Marαufacture of footwear according to any of claims 6 to 9 wherein the resilient material is of foam texture, or assumes such texture, after injection into the said at least one cavity. 11. Manufacture of footwear according to claim 10 wherein the foam density of the resihent material is of the order of 0.2 to 0.3g/cm. 12. Manufacture of footwear according to claim 10 or 11 wherein the resihent material of foam texture and any hardening agent therewith has the property of forming a skin thereabout after injection into the said at least one cavity, which skin resists water penetration into the body of the foam texture resihent material. 13. Manufacture of footwear according to any of claims 6 to 12 wherein the resihent material is injected into said at least one cavity through any convenient part of the assembly of the footwear such as through a small bore in the outer sole or through the insole. 14. Manufacture of footwear according to any of claims 6 to 13 wherein one or more vent holes are provided to the said at least one cavity through a convenient part of the footwear assembly such as through the outer sole to allow escape of air which would otherwise be trapped in the cavity and so permit full and intimate filling of the latter by the resihent material. 15. Manufacture of footwear according to any of claims 6 to 14 wherein a heel unit or portion of or to the outer sole also receives the resihent material between it and the insole during the injection of said resi ent material. 16. Manufacture of footwear such as a shoe when substantially as herein described with reference to the accompanying drawings. 17. Footwear such as a shoe when manufactured by the method of manufacture according to any of claims 6 to 16.

Inventors: GEE HARRY HOWARD, GEE, HARRY, HOWARD
Applicants: GEE HARRY HOWARD, WHITE & CO EARLS BARTON LIMITE, GEE, HARRY, HOWARD, WHITE & CO. (EARLS BARTON) LIMITED
Application year: 1995
Main classification: B29D31
IPC codes: A43B9, A43B13, A43B21, B29D31