EP0378944B1 - Preform of orthopaedic insole - Google Patents

Description

The subject of the invention is a method of manufacturing blanks for orthopedic soles, or plantar orthotics.

The blanks thus manufactured must be worked in such a way as to be adapted to the affection from which the patient suffers and to his mode of fitting.

The existing methods use corrective elements glued flat to a base leather, which results in a loss of height of the therapeutic reliefs by deformation of the orthopedic sole when it is used in the shoe. These corrective elements are generally made of cork or agglomerate, materials without flexibility, often poorly tolerated by suffering feet or not allowing at all the fitting of particularly susceptible feet.

Document DE-A-3,700,094 relates to a sole with a flat underside: this sole, a finished product, has no medical function since its sole role is to absorb perspiration from the arch of the foot. The heat-crosslinkable plastic material with open cells is effectively absorbent for liquids.

Document GB-A-542.551 relates to the insole of a shoe, which sole comprises two superposed layers: the non-deformable lower layer comprising rubber and have a flat lower face; the upper layer, which can be shaped by the user's foot, also includes rubber. The assembly is vulcanized at a temperature such that the vulcanization accelerator present in the lower layer reacts, while that present in the upper layer does not react. Consequently, the lower layer develops all of its characteristics while the upper layer remains deformable and develops all of its characteristics after a certain time.

The document AU-B-443.678 relates to a composition based on cork and a polyurethane resin, which can be used for the production of an insole for shoes: cork and natural rubber which is vulcanizable by expansion, unlike synthetic rubbers.

Document US-A-2,404,731 relates to a sole comprising a sponge rubber layer caught between two upper and lower layers. The latter is flat.

Document DE-A-1 616 154 describes an orthopedic sole comprising a relatively thick inner layer covered on each side by a thin layer of cork. The bottom layer, consisting mainly of rubber and cork, also includes soft spots formed from vulcanized sponge rubber.

The blanks for orthopedic soles which are the subject of the present invention are produced transversely curved and arched longitudinally at physiological heel heights, for example for men 2.5 cm, women 4.5 cm and children 1.5 cm. The orthopedic insoles obtained after adaptation to each particular case perfectly coincide with the relief of the shoe, avoiding any loss of efficiency since there is no deformation of the therapeutic elements. In addition, it is possible to choose the density of the material best suited to the pathology of the case to be fitted, thus providing the patient with maximum relief and comfort.

These blanks are obtained by a hot vulcanization process in molds of a microcellular material essentially consisting of a mixture of natural rubber and cork in the proportions described below.

• des ébauches vulcanisées sur un cuir de base ayant subi un tannage spécial et un traitement de pré-chauffe,
• des ébauches vulcanisées sans cuir de base, le matériau lui-même tenant lieu de base sous toute la longueur du pied.

Thanks to this process, two types of blanks can thus be obtained:

• vulcanized blanks on basic leather that has undergone special tanning and preheating treatment,
• vulcanized blanks without base leather, the material itself serving as the base under the entire length of the foot.

By the same vulcanization process, plates of the same material are obtained, in different thicknesses and different densities, serving to make subsequent rectifications.

The accompanying drawings illustrate, by way of example, the blanks for orthopedic insoles and the molds according to the present invention.

Figure 1 shows a vulcanized blank on a basic leather, in profile view.

Figure 2 shows the same blank in section along the axis AA.

Figure 3 shows the same blank from above.

FIG. 4 represents a blank vulcanized directly, in profile view.

FIG. 5 represents the same blank in section along the axis BB.

Figure 6 shows the same blank from above.

FIG. 7 represents a mold to be vulcanized in longitudinal section.

FIG. 8 represents a mold to be vulcanized in cross section along the axis DD.

The composition of the mixture used to obtain the microcellular material is as follows: natural rubber 50 to 70 kg, titanium oxide 3 to 4.2 kg, zinc oxide 3 to 4.2 kg, antioxidant 0.4 to 0, 8 kg, carbonate of magnesia 2.5 to 3.5 kg, olein 4 to 6 kg, stearin 5 to 7 kg, baking soda 2 to 3 kg, blowing agent 2 to 3 kg, accelerator 1 to 3 kg, sulfur 0 , 5 to 2 kg, cork 6 to 35 kg.

The respective amounts of the constituents vary according to the density to be obtained. For example, the following mixture is used to obtain the so-called "normal" density or reference density: natural rubber 60 kg, titanium oxide 3.6 kg, zinc oxide 3.6 kg, antioxidant 0.6 kg, carbonate of magnesia 3 kg, olein 4.5 kg, stearin 5.4 kg, baking soda 2.5 kg, blowing agent 2.5 kg, accelerator 1.8 kg, sulfur 0.9 kg, cork 11.6 kg, for a mixture final weight of 100 kg.

In addition, the material described in the present invention does not cause any allergy. It is light, airy and rot-proof.

The implementation of the invention is done as follows: after kneading and cylindering, quantities of mixture (1) are dosed and cut then placed in molds (3) in two parts whose internal shape is curved and arched at physiological heel heights, either on a leather base (2) placed in the lower part of the mold or directly, the material filling the entire length of the mold.

The molds thus loaded are introduced into an oven and heated.

The mixture vulcanizes and, after cooling and demoulding, blanks of one-piece orthopedic soles are obtained, that is to say of which the relief is continuous and does not have isolated and independent parts from each other. These blanks can include in their structure one or more different densities of the microcellular material described.

The plates of material for grinding the soles with progressive correction are obtained by the same process using molds with a strictly flat bottom and cover.

A large set of molds makes it possible to obtain a wide variety of blanks.

Different types of corrective reliefs are produced with or without basic leather, for men from size 38 to size 46, for women from size 36 to size 44, for children from size 21 to size 38, each of these sizes itself being available in two different widths and in several densities.

The different shapes and densities of the blanks of orthopedic insoles thus obtained allow, after adaptation by a specialist (orthopedist, podo-orthotist, pedicure-podiatrist, pharmacist-orthopedist, supplier of large devices ...) all fitting techniques and all the types of custom-made foot orthotics, whether for correction, compensation or isolation.

These one-piece, curved and cambered blanks work perfectly with the sanding drum. There is no risk of the micro-cellular material being torn off which adheres perfectly to the base leather.

The orthopedic insoles thus obtained adapt perfectly to the relief of the shoe, avoiding any loss of efficiency since there is no deformation of the therapeutic elements.

The rectification material presented in plates is the essential complement to the evolution of corrections.

Claims (3)

1. A preform of an orthopaedic one-piece insole, comprising a microcellular material (1), characterised in that its lower face is cambered (C) longitudinally and curved (G) transversely and in that the microcellular material (1) comprises a mixture of cork and natural hot-vulcanized rubber.
2. A preform of an orthopaedic one-piece insole, for the purpose of the medical clothing of feet, comprising a microcellular material (1), characterised in that the microcellular material (1) is produced from the mixture of the following components: natural rubber 50 to 70 kg, titanium oxide 3 to 4.2 kg, zinc oxide 3 to 4.2 kg, antioxidant 0.4 to 0.8 kg, magnesium carbonate 2.5 to 3.5 kg, olein 4 to 6 kg, stearin 5 to 7 kg, sodium bicarbonate 2 to 3 kg, swelling agent 2 to 3 kg, accelerator 1 to 3 kg, sulphur 0.5 to 2 kg, cork 6 to 35 kg, the respective quantities of these components varying according to the density of the material to be obtained after a hot vulcanization.
3. A preform according to claim 1 or claim 2, characterised in that it has, on its lower face, a base of leather (2).

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