PROCESS FOR MANUFACTURING A FOOTWEAR AND FOOTWEAR PARTS

Abstract

The invention is directed to a process for producing a outsole or inner sole of a footwear comprising the following steps (a) providing a first form negative mould of the outsole or inner sole comprising of at least one formed plastic sheet as obtained by thermoforming using a first master mould corresponding with the shape of a first side of the outsole or inner sole, (b) adding a liquid curable composition to the first form negative mould, and (c) solidifying the curable composition wherein a solidified outsole or inner sole is obtained and wherein the first form negative mould is removed from the solidified outsole or inner sole.

Claims

1. Process for producing an outsole or inner sole of a footwear comprising the following steps (a) providing a first form negative mould of the outsole or inner sole comprising of at least one formed plastic sheet as obtained by thermoforming using a first master mould corresponding with the shape of a first side of the outsole or inner sole, (b) adding a liquid curable composition to the first form negative mould, and (c) solidifying the curable composition wherein a solidified outsole or inner sole is obtained and wherein in step (c) the solidified outsole or inner sole as obtained is removed from the first form negative mould.

2. Process according to claim 1, wherein after performing step (b) a second form negative mould of the outsole or inner sole comprising of at least one formed plastic sheet as obtained by thermoforming is placed on top of the partly cured liquid curable composition.

3. Process according to claim 1, wherein in step (a) an outsole or inner sole is produced and wherein during step (c) a further layer of a different liquid curable composition is added on top of the partly cured curable composition and wherein the second form negative mould if present or the planar sheet if present are removed prior to adding the different liquid curable composition-.

4. Process according to claim 1, wherein in step (a) the first form negative mould is combined with a third form negative mould of the outsole or inner sole comprising of at least one formed plastic sheet as obtained by thermoforming using a third master mould corresponding with the shape of a second side the outsole or inner sole to obtain a full mould of the outsole or inner sole and that in step (b) the liquid curable composition is added to the full mould via a gating opening.

5. Process according to claim 4, wherein in step (c) the solidified outsole or inner sole as obtained is removed from the first and third form negative mould.

6. Process according to claim 1, wherein the first form negative mould is supported by the first master mould or by an equally shaped support when performing step (b).

7. Process according to claim 6, wherein in step (b) the master mould or the equally shaped support is cooled when the temperature of the liquid curable composition added in step (b) is higher than the softening point of the formed plastic sheet of the first form negative mould.

8. Process according to claim 1, wherein the formed plastic sheet of the first form negative mould is obtained by thermoforming using a thermoforming packaging machine in a continuous process.

9. Process according to claim 2, wherein the formed plastic sheet of the second form negative mould is obtained by thermoforming using a thermoforming packaging machine in a continuous process.

10. Process according to claim 1, wherein the first master mould of step (a) is obtained by 3D printing.

11. Process according to claim 10, wherein the thickness of the master mould is between 0.5 and 5 mm.

12. Process according to claim 10, wherein the material of the master mould is ABS Plastic manufactured using Fused Deposition Modelling FDM, Selectively Laser Sintered SLS Nylon or Selectively Laser Sintered SLS Alumide®.

13. Process according to claim 1, wherein the liquid curable composition is cold pour curing composition.

14. Process according to claim 13, wherein the cold pour curing composition comprises liquid TPU or liquid PU.

15. Process according to claim 13, wherein the liquid curable composition further comprises regrind injection moulded EVA foam particles and/or regrind injection moulded PU particles.

16. Process according to claim 1, wherein the liquid curable composition comprises a polymer in its molten state.

17. Process to manufacture a footwear comprising the following steps, (i) manufacture of an outsole according to the process according to claim 1, (ii) placing an upper on top of the outsole obtained in step (i) and (iii) connecting the upper to the outsole.

18. Process according to claim 17, wherein in step (i) a further midsole is provided on top of the outsole according to the process of claim 5 and wherein in step (iii) the upper is connected to the obtained outsole and midsole.

19. Process according to claim 17, wherein an inner sole as obtained by a process according to claim 1 is placed in the footwear obtained in step (iii).

20. Process according to claim 17, wherein the upper is obtained by a thermoforming process.

21. Process according to claim 17, wherein the connecting in step (iii) is at least one of gluing, welding, high frequency welding, ultrasonic welding, laser welding, pressing, sewing, screwing, riveting, melting together, clipping together, sealing, subjecting to a heat and pressure treatment, or subjecting to a steaming treatment.

Description

[0046] The invention will be illustrated by FIG. 1. FIG. 1 is a schematic representation of a possible continuous process to manufacture an outsole for a footwear. In the upper drawing of FIG. 1a roll (1) is shown from which a plastic sheet (4) runs to the left hand of the figure. The sheet (4) runs between an upper tooling part (2) and a lower tooling part (3) of a thermoforming forming station. The lower tooling part (3) comprises a master mould at its upper side. In the lower figure upper and lower tooling parts sandwich the plastic sheet (4) resulting in that a form negative mould (5) of the outsole is obtained. This mould (5) is filled with a liquid curable composition from container (6). The mould with the curing composition is shown as filled mould (7). The mould with the fully cured composition is shown as mould (8). The outsole (7a) may be separated from the mould or remain in the mould to be combined with other footwear parts as shown in FIG. 3.

[0047] FIG. 2 shows a well known roll stock thermoforming process to make an upper. From roll (10) a sheet (13) of for example EVA foam is drawn to the left. The sheet (13) runs between an upper tooling part (11) and a lower tooling part (12) of a thermoforming forming station. The lower tooling part (12) comprises a master mould at its upper side. In the lower figure upper and lower tooling parts sandwich the sheet (13) resulting in that an upper (13) is obtained.

[0048] FIG. 3 shows the line-up as in FIG. 1 as part of a footwear manufacturing process. The mould (8) with the cured outsole (7a) is combined with a midsole (14) midsole (14) on top of the outsole (7a). The outsole (7a) does not have to be fully cured when the midsole (14) is fixed on to the outsole (7a). On top of the stack of outsole (7a) and midsole (14) as shown in FIG. 4, an upper (13) is placed (see also FIG. 5). The upper (13) may be any upper or one as prepared by the process illustrated in FIG. 2. In a sealing station (15) the upper (13) is connected to the outsole.

[0049] FIG. 6 shows different packaged outsoles (7a) as sandwiched between a first form negative mould (23) and a second form negative mould (28).

[0050] The invention will be further illustrated by the following non-limiting example.

EXAMPLE

[0051] In this example reference will be made to FIGS. 7-10 which Figures schematically show the different steps and moulds used in this example. In this example an outsole (29) is prepared according to the process of this invention. A first master mould (22) made of ABS was prepared using Fused deposition modelling (FDM). The master mould (22) was printed in four separate parts and assembled to one piece. The first master mould (22) resembles the form negative shape of the bottom of the outsole (29). The mould (22) is only slightly larger than the exact form negative shape of the desired outsole (29). Also a second master mould (27) was made of ABS using Fused deposition modelling (FDM). Again the second master mould (27) was printed in four separate parts and assembled to one piece. The second master mould (27) resembles the form negative shape of the upper end of the outsole (29) to be prepared. The first and second master mould were prepared within 12 hours. When using quicker and more printers one can imagine that such a process may even be performed in a shorter time span. Using larger printers will enable one to make the first and second mould in one piece by means of 3D printing.

[0052] A first form negative mould (23) of the outsole consisting of one formed plastic sheet (21) of a thermoplastic elastomer having a thickness of 0.22 mm was obtained by thermoforming using the above first master mould (22). The mould (23) has a planar surface (23a) and a recess (23b) within the planar part (23a) corresponding with the bottom of the outsole (29) and the sides of the outsole (29).

[0053] A second form negative mould (28) of the outsole (29) consisting of one formed plastic sheet (25) of a thermoplastic elastomer having a thickness of 0.22 mm was obtained by thermoforming using the above second master mould (27). The master mould (27) has a planar part (27a) and a recess (27b) within the planar part (27a) corresponding with the upper end of the outsole (29) and part of the sides of the outsole (29).

[0054] The first (23) and (28) second form negative moulds were produced at a rate of 6 per minute using a standard thermoforming packaging machine. This could be improved by using more master moulds simultaneously and/or by making use of larger thermoforming packaging machine.

[0055] The first form negative mould (23) was placed back into a first support (30) which was equally shaped as the first master mould (22). To the recess (23b) of the first form negative mould (23) a cold pour industrial liquid rubber product called PMC-770 as obtained from FormX in Amsterdam, The Netherlands was poured in at room temperature and ambient pressure. The volume (29a) added was about the volume of the desired outsole (29). After adding the cold pour curable composition the second form negative mould (28) was placed on top of the filled first form negative mould such that the planar surfaces (23a, 28a) contact each other and wherein the second form negative mould (28) presses the top surface (29b) of the cold pour liquid slightly downwards. Any excess liquid may escape via a purge line (not shown) in one or both planar surfaces (23a,28a). On top of the second form negative mould (28) a second support (31) is placed and the entire stack as obtained is pressed together. Because the second form negative mould has extensions, namely the recess (28a), which penetrate the partly cured liquid (see e.g. FIG. 10) the support (31) is also a form negative of the second master mould (27).

[0056] After 15 minutes the first and second supports (30,31) were removed from the stack and after 12 hours the fully cured outsole (29) was removed from the filled set (34) of the two thermoplastic elastomer moulds (23,28). This clearly shows the advantages of this process, namely that the time required to use complex master moulds (22,27) or shaped supports (30,31) in the curing process is relatively short. The longer curing period is performed making use of cheap and disposable thermoplastic elastomer moulds (23,28). The moulds (23,28) may after use be recycled to a sheet of material which can be reused in the thermoforming process.

[0057] In this example the moulds (22) or supports (30,31) were not cooled or heated. But if required this may be performed by the gas or liquid flows (33,32) as shown in FIGS. 9 and 10. Instead of the above referred to cold pour industrial liquid rubber similar shaped products have been prepared by this method using an urethane rubber PMC-780 WET, urethane rubber PMC-780 DRY and urethane TASK 16 adhesive.

[0058] In this example a outsole was prepared having a shaped bottom and upper side. This procedure may also be applied for the manufacture of other objects or multilayer objects. The invention is thus also directed to a Process for producing any product comprising the following steps [0059] (a) providing a first form negative mould of one end of the product comprising of at least one formed plastic sheet as obtained by thermoforming using a first master mould corresponding with the shape of the one end of the product, [0060] (b) adding a liquid curable composition to the first form negative mould, [0061] (b1) placing a second form negative mould of the other side of the product comprising of at least one formed plastic sheet as obtained by thermoforming on top of the partly cured liquid curable composition and [0062] (c) solidifying the curable composition wherein a solidified product is obtained.

[0063] Preferred embodiments are those described for the outsole and innersole above.