The invention, footwear midsole, method of manufacture and mould for the manufacture thereof, relates to a footwear midsole, footware such as sandals or closed shoes, and a method for manufacturing a footwear midsole obtained by moulding. The midsole has a first body with a hollow or recess that determines perimeter walls in said first body, made of a first material preferably composed of a mixture of rubber, or polyurethane, and cork, with an intermediate filling of a second material that extends above the perimeter walls and a third material, acting as a lining, overlaid on the second material, such that the second material, between the walls of the first material and the lining determines a variable geometric design or shape depending on the design of the midsole. The method uses a special mould which, in addition to a lower part and an upper part, is equipped with an intermediate piece, such that the method presents a casting phase between the aforementioned walls of a filling layer of said second material, preferably polyurethane.
The field of application of the present invention is within the sector of the footwear industry, focusing specifically on the area of the manufacture of midsoles for any type of footwear, such sandals or closed shoes.
As a reference to the current state of the art, it should be noted that footwear midsoles that have at least one essential part made of a material that combines rubber with cork, and that have a main characteristic of making the midsoles lighter, usually being intended for summer footwear, are known.
The main drawback of these midsoles is that they are usually composed of said rubber with cork material that has two densities, a higher density in the outer area of the midsole, which is therefore harder, to provide stiffness and solidity to the midsole, and an inner area, which is therefore softer than the previous one, to provide elasticity and comfort to the user on the part that supports the sole of the foot the most. Said first material is covered with a lining. The presence of a material with two densities means that in the area where the two materials meet, usually on the periphery, there is a support area of the sole of the foot that is more uncomfortable than the inner area because the foot will rest on a softer area on the inside of the midsole but also on a harder area on the outside area of the midsole. Although the difference in densities of the material between the inner and outer areas of the midsole may vary, providing greater comfort to the user by supporting the sole of their foot on the footwear midsole, there is always that difference in density between the two areas which causes a place on the footwear midsole to be uncomfortable for the foot that rests on it. Although the foot is mostly supported on the inside of the footwear midsole, there is always a part of the foot, no matter how small, resting on the harder outer area, which is therefore more uncomfortable. Alternatively, the material can have a single density, which must be rigid in order to maintain the stability of the midsole, for example, with the exterior stiffness of the midsole described above, which results in a more uncomfortable midsole for the user due to the aforementioned stiffness.
The present invention allows the entire sole of the foot to rest on a surface with the same density, thus providing greater comfort to the user and overcoming the existing problems in the sector.
For the purposes of the present invention, a footwear has:
The leather or upper part of the footwear can be attached to the midsole by different means and to different parts of it. For example, in the case of a sandal, the leather strip, acting as upper part of the footwear, that covers the instep of the foot can be attached between the midsole and the sole, or glued to the sides, or both.
The first object of the present invention is a footwear midsole according to claim 1.
Specifically, this footwear midsole incorporates:
The aforementioned midsole, in addition to solving the existing drawbacks in the midsoles of the state of the art, presents an aesthetic advantage since it allows the geometric shape formed by the second material in that intermediate layer or area, between the first body and the lining, on the periphery of the midsole, to vary depending on the desired design.
The second material, introduced in the hollow of the first body by casting, is preferably polyurethane, while the lining of the midsole is made of a third material, which may be natural or synthetic, according to the needs. The hollow in the first body may have different shapes and different depths.
Although the first preferred material has a cork base, for the manufacture of lighter midsoles, it is also possible to use other types of materials that give solidity and stiffness to said first body, these materials may be TPU (thermoplastic polyurethane), TR (thermoplastic rubber), polyurethane, rubber, among others.
Likewise, although this description makes reference to midsoles for footwear, which may be any kind of footwear, such as sandals or closed shoes, said midsoles may constitute footwear outsoles when they also incorporate a base under the first body of the midsole which makes them suitable for use as an outsole. In addition, the midsole may or may not be anatomical, depending on the shape of the upper part of the midsole on which the foot rests. Additionally, it is possible to obtain a complete shoe, i.e., an midsole with an outsole, a lining and even the leather of the footwear, depending on the method of manufacture used after the manufacturing of the midsole object of the invention.
The design of the second material in the intermediate area of the midsole, between the walls of the first body and the lining, can vary between the upper side of the wall of the first body and the upper side of the second material, which coincides with the lining, and can also have variations in the side surface of the second material in said intermediate area. Consequently, the upper side of the perimeter wall, as well as the upper side of the intermediate area, may incorporate straight lines, curved lines, wavy lines or zigzag lines, among other shapes, and the side surface of this intermediate area can incorporate any embossed shape, such as, for example, the logo or brand of the footwear manufacturer, as well as any other design. Likewise, the aforementioned intermediate area may itself be embossed such that the entire intermediate area may protrude with respect to the perimeter wall of the first body or be recessed with respect to said perimeter wall.
A second object of the invention is a method for the manufacture of an midsole like the one described above according to claim 4.
Specifically, the method for manufacturing footwear midsoles, obtained by moulding, with a first hollow lower body of a first material, preferably, rubber with cork or polyurethane with cork, an upper lining and an intermediate filling, preferably polyurethane, comprises the following steps:
At least two alternatives are considered for the arrangement of the lining on the upper part of the mould, that is, for step c):
After the second material has expanded and cured, the complete midsole is extracted with the perimeter tab on the first body and the lining with dimensions larger than those of the midsole, to subject this intermediate midsole to a process of manual die-cutting or refining of the surplus from the lining, from the tab of the first material and even of the second material that may sometimes be present, in order to adjust the dimensions of the lining, tab or second material to the perimeter dimensions of the midsole.
After removing the surplus, the finished midsole is available according to the characteristics mentioned above. This midsole may be subjected to other processes, such as cleaning, and then incorporated into footwear, a sandal or a closed shoe. For this, it will be necessary to add the leather and the sole to the midsole and thus constitute the footwear. The sole can be added later to the manufacturing of the midsole or it can be attached to the lower surface, the surface opposite the hole or recess, of the first body of the midsole, prior to its introduction into the mould, so that in the latter case the midsole would be manufactured with the sole already incorporated. Likewise, the leather of the footwear is added to the midsole after the latter is manufactured:
A third object of the present invention is a mould according to claim 6. The mould of the invention for the manufacture of footwear midsoles, according to the method described above, comprises:
Preferably, and to facilitate the positioning of a lining in the mould, the edge of the intermediate plate comprises at least two holes and the protrusion of at least two points, sharp elements or nails from the upper part, positioned to correspond to one another so that when the upper part of the mould is positioned on the intermediate plate, the points, nails or sharp elements are inserted into the holes in said plate.
In addition to incorporating the lining, it will be necessary to add to the midsole with the lining incorporated the leather of the footwear, shoe or sandal.
It should be noted that the design of the midsole on its periphery, in particular in the intermediate layer of the second material, is determined by the side wall of the intermediate plate of the mould, i.e., the side wall that determines the through opening of said plate. Said side wall may have a smooth surface or a concave or convex surface. In addition, different types of embossing or bas-reliefs with different designs can be arranged on this surface, such as, for example, the brand or logo of the footwear for which the midsole is intended, or other figures, such as animals, flowers, geometrical figures, etc.
Likewise, the upper surface of the lower part of the mould is complementary to the lower surface of the intermediate plate, and depending on the shapes of these surfaces, will result in different shapes on the lower side of the intermediate layer of the second material, such as, for example, flat, wavy or sloping lines.
The height of the intermediate layer of the second material is determined by the height of the wall of the intermediate plate.
The main advantages of the present invention are:
As a complement to the description of the present invention, and for the purpose of helping to make the features of the invention more readily understandable, this specification is accompanied by a set of drawings which form an integral part of it and, by way of illustration and not limitation, represent the following:
In view of the aforementioned figures, an exemplary embodiment of the midsole, mould and method objects of the invention are described below.
As shown in
The mould further comprises an intermediate plate (4), which is placed on the lower part (2) of the mould and which has a through opening (4a) approximately coinciding with the void or hollow of the first body (11). Likewise, said intermediate plate has a side wall that delimits the through opening (4a) and a perimeter edge (4b) that will determine the shape of the upper surface of the midsole (10). The lower surface of the intermediate plate is located on the perimeter tab of the first body (11) of the midsole (11). In this preferred form, said intermediate plate also has a recess (4c) over the perimeter edge (4b) determined by a second wall on the perimeter of the edge (4b). Alternatively, the intermediate plate may possibly not include the recess (4c) with the wall on its perimeter, i.e., it may be a plate without said second wall that determines the aforementioned recess. The intermediate plate (4) may incorporate slots (7) for the outlet of air or gases.
The last part of the mould is the upper part (3) of the mould, preferably comprising a protrusion (3a) intended to be inserted into the recess (4c) of the intermediate plate. In addition, the protrusion (3a) of the upper part (3) of the mould (1) has several points (5), or pointed elements, preferably at least two, such that when the upper part (3) of the mould is lowered or placed on the intermediate plate (4), they fit into holes (6) made to coincide with the perimeter edge (4b) of said intermediate plate (4). If the intermediate plate does not have the second side wall, i.e., if it does not have the recess, the upper part of the mould may not incorporate the aforementioned protuberance.
To use the aforementioned mould (1), the first body (11), preferably of a first material that is rubber with cork, is inserted tightly in the recess (2a) of the lower part (2) of the mould, such that the perimeter tab of said first body rests on the upper surface of the lower part (2) of the mould.
Next, the intermediate plate (4) is lowered or placed on the lower part (2) of the mould, such that the lower surface of the plate (4) rests on the perimeter tab of the first body (11).
The lining (13) of the footwear midsole, made of a third material, which may be natural, leather, synthetic, or microfibre, is then placed on the plate (4), covering the central opening (4a) of the plate. The upper part (3) of the mould is then lowered or positioned on the intermediate plate (4), causing the points (5) of the protrusion (3a) to pass through the lining (13), to fix its position in the mould, with said points (5) being inserted into the holes (6) on the edge (4b) of the intermediate plate while the protrusion (3a) is inserted into the recess (4c) of the plate (4). After this operation, the upper part (3) of the intermediate plate (4) is raised or separated again.
The next step is to cast the second material (12), preferably polyurethane, as filler material for the midsole (10), inside the first body (11), through the opening (4a) of the intermediate plate (4). Once said polyurethane (12) has been cast, the upper part (3) of the mould is again lowered or positioned on the intermediate plate (4) and the polyurethane is allowed to expand and cure.
Once the polyurethane (12), or second material, has cured, the upper part (3) and the intermediate plate (4) of the mould (1) are raised and the footwear midsole (10) is removed, which has several surplus areas (10a) generated by the perimeter tab of the first body (11), to the excess lining (13) and sometimes to the excess of the second material (12). These surplus areas are removed by manual or refined die-cutting.
Said midsole will have a first body (11) of a first material, preferably a rubber material with cork, with a perimeter wall of said material, an intermediate layer of a second material (12), preferably polyurethane, arranged immediately on the perimeter wall of the first body (11) and a lining (13) of a third material, preferably leather or microfibre, overlaid on the second material (12).
The design of the intermediate layer of the second material (12) is defined by the configuration of the side wall of the opening (4a) of the intermediate plate (4). This side wall may be, for example, concave, convex, flat, among other options, and in addition, may incorporate embossing or bas-reliefs, which may have different designs, such as animals, trademarks, flowers, geometric patterns, etc. The height of this wall will provide the height to the intermediate layer (12) of the second material.
Additionally, the lower surface of the intermediate plate (4) is complementary to the upper surface of the lower part (2) as well as to the shape of the perimeter tab of the first body (11). Consequently, by alternating the shapes of said surfaces, the shape of said intermediate layer of the second material (12) is modified.
Preferably, all of the parts (2, 3 and 4) of the mould (1) are joined together by a joint (8) and, in addition, they are equipped with closure elements (9) to seal the mould (1) prior to casting between the lower part (2) and the intermediate plate (4) and subsequently during the expansion and curing of the second material (12) after lowering the upper part (3) of the mould.
Number | Date | Country | Kind |
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20382118.6 | Feb 2020 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/ES2021/070113 | 2/18/2021 | WO |