Injection-molding method

Abstract

The invention concerns a method of producing an article of footwear comprising: providing an upper; providing a mold and opening the mold; inserting the upper into the open mold; closing the mold; and injecting a pressurized molten resin, wherein, after the injecting, there is a gap filled with the resin between a side wall of the mold and an outer surface of at least a first portion of the upper, wherein the gap is essentially zero at a contacting point, wherein the gap increases gradually from the contacting point in at least a first region of the mold.

Claims

1. A method of producing an article of footwear comprising: providing an upper; providing a mold and opening the mold; inserting the upper into the open mold; closing the mold; and injecting a pressurized molten resin, wherein, after the injecting, there is a gap filled with the resin between a side wall of the mold and an outer surface of at least a first portion of the upper, wherein the gap is essentially zero at a contacting point between the side wall of the mold and the outer surface of at least the first portion of the upper, wherein the gap increases gradually from the contacting point in at least a first region of the mold, wherein the resin forms a coating along the outer surface of the first portion of the upper, and the resin forms at least a part of a sole element disposed along an outer surface of a bottom region of the upper, wherein the first portion of the upper is disposed along a side of the upper, and the bottom region of the upper is disposed below the first portion of the upper and extends from a lateral side to a medial side of the upper, and wherein closing the mold compresses at least a second portion of the upper, and wherein the second portion of the upper is compressed by a first compression distance at a first part of the second portion of the upper and by a second compression distance at a second part of the second portion of the upper, wherein the first compression distance is smaller than the second compression distance.

2. The method of claim 1, wherein injecting the pressurized molten resin further compresses at least a third portion of the upper such that a gap opens between an outer surface of the third portion of the upper and the side wall of the mold.

3. The method according to claim 1, wherein the gap increases by less than 1 mm per mm of a distance from the contacting point in at least the first region of the mold, wherein the distance is measured along the outer surface of the first portion of the upper.

4. The method according to claim 1, wherein the side wall contacts the outer surface of the first portion of the upper at the contacting point at an angle of less than 30 degrees.

5. The method according to claim 1, wherein the first region of the mold is arranged within 5 mm below the contacting point.

6. The method according to claim 1, wherein the upper is arranged on a shoe last, prior to inserting the upper into the open mold.

Description

SHORT DESCRIPTION OF THE FIGURES

(1) In the following, exemplary embodiments of the invention are described with reference to the figures.

(2) FIG. 1 shows an exemplary article of footwear according to the present invention;

(3) FIGS. 2A-E shows an exemplary article of footwear according to the present invention;

(4) FIG. 3 shows another exemplary article of footwear according to the present invention;

(5) FIG. 4 shows another exemplary article of footwear according to the present invention;

(6) FIG. 5 shows another exemplary article of footwear according to the present invention;

(7) FIGS. 6A-D show exemplary molds and illustrate methods for operation thereof;

(8) FIGS. 7A-B illustrate pinching and flashing in a conventional shoe;

(9) FIG. 8 shows another exemplary article of footwear according to the present invention;

(10) FIG. 9 shows another exemplary article of footwear according to the present invention;

(11) FIG. 10 shows another exemplary article of footwear according to the present invention; and

(12) FIG. 11 shows another exemplary article of footwear according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(13) In the following some embodiments of the invention are described in detail. It is to be understood that these exemplary embodiments can be modified in a number of ways and combined with each other whenever compatible and that certain features may be omitted in so far as they appear dispensable.

(14) FIG. 1 shows an exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises: an upper 11; an injection-molded region comprising a resin, wherein the resin at least partly coats an outer surface of the upper 11, wherein the resin coating 12 ceases at a first position, and wherein a thickness of the resin coating 12 increases gradually in at least a first region of the upper 11. The resin is for forming a sole element 13 and additionally acts as a coating 12 applied on the upper 11. The article of footwear 10 further comprises a tongue 15 and shoe laces. In this example the article of footwear 10 is a running shoe.

(15) The thickness of the resin coating 12 increases by less than 1 mm per mm of a distance from the first position 20 in at least the first region 19 of the upper 11, wherein the distance is measured along the outer surface 17 of the upper 11. The distance is a height determined from the first position 20 towards a bottom region of the upper 11.

(16) In this example, the upper 11 is weft-knitted. The upper 11 shown in FIG. 1 may be produced by any method disclosed herein using a mold 21 as disclosed herein.

(17) FIGS. 2A-E show a schematic of an article of footwear 10 according to the present invention. FIG. 2A shows a lateral view, while FIGS. 2B-E show a cross-sectional view through the sections indicated with E-E, D-D, C-C, and B-B, respectively, in FIG. 2A.

(18) The article of footwear 10 comprises: an upper 11; an injection-molded region comprising a resin, wherein the resin at least partly coats an outer surface 17 of the upper 11, wherein the resin coating 12 ceases at a first position, and wherein a thickness of the resin coating 12 increases gradually along a height, in at least a first region 19 of the upper 11, wherein the height is measured from the first position 20 towards a bottom region of the upper 11 along the outer surface 17 of the upper 11. The height is measured on the surface 17 of the upper 11, i.e. below any resin coating 12, if present.

(19) The resin forms a sole element 13 of the article of footwear 10. The injection-molded region, which comprises the coating 12 and the sole element 13 is devoid of any pinching. The sole element 13 is a midsole of the article of footwear 10 and an additional outsole 16 is attached by infrared welding.

(20) A first exemplary first region 19a is shown in the cross-sectional cut from E-E shown in FIG. 2B. The thickness of the resin coating 12 increases approximately symmetrically on both sides by about 0.6 mm per mm of height, an average angle formed by the surface 18 of the coating 12 with the outer surface 17 of the upper 11 is therefore about 31°, i.e. the arctan(0.6 mm/1 mm).

(21) The outer surface 18 of the resin coating 12 forms an angle of about 35° with an outer surface 17 of the upper 11 at a first exemplary first position 20a.

(22) A second exemplary first region 19b is shown in the cross-sectional cut from D-D shown in FIG. 2C. The thickness of the resin coating 12 increases approximately symmetrically on both sides by about 0.4 mm per mm of height, an average angle formed by the surface 18 of the coating 12 with the outer surface 17 of the upper 11 is therefore about 22°, i.e. the arctan(0.4 mm/1 mm). However, in this cut, the coating 12 extends significantly higher on a left side than on a right side of the exemplary upper 11.

(23) The outer surface 18 of the resin coating 12 forms an angle of about 30° with an outer surface 17 of the upper 11 at a second exemplary first position 20b.

(24) A third exemplary first region 19c is shown in the cross-sectional cut from C-C shown in FIG. 2D. The thickness of the resin coating 12 increases on a left side by about 0.9 mm per mm of height and on a right side by about 0.6 mm per mm of height, an average angle formed by the surface 18 of the coating 12 with the outer surface 17 of the upper 11 is therefore about 42° on a left side, i.e. the arctan(0.9 mm/1 mm) and about 31° on a right side. In this cut, the coating 12 extends to approximately the same level on a left side as on a right side of the exemplary upper 11.

(25) The outer surface 18 of the resin coating 12 forms an angle of about 50°, i.e. more than 45°, with an outer surface 17 of the upper 11 at a third exemplary first position 20c on a left side and about 40° in a right side.

(26) In the exemplary cuts shown in FIGS. 2B-D, the first region 19a-c of the upper 11 extends to 10 mm below the first position.

(27) A fourth exemplary first region 19d is shown in the cross-sectional cut from D-D shown in FIG. 2C. The thickness of the resin coating 12 increases approximately symmetrically on both sides by about 0.35 mm per mm of height, an average angle formed by the surface 18 of the coating 12 with the outer surface 17 of the upper 11 is therefore about 19°, i.e. the arctan(0.35 mm/1 mm). However, in this cut, the coating 12 extends significantly higher on a left side than on a right side of the exemplary upper 11.

(28) The outer surface 18 of the resin coating 12 forms an angle of about 19° with an outer surface 17 of the upper 11 at a fourth exemplary first position 20d.

(29) A smaller angle may be preferred to generate a unique look mimicking a fused single-piece shoe where the upper and midsole are indistinctive. In combination with the upper this effect can be enhanced as the upper could have a specific topography allowing the PU to flash up in some parts (thinner upper) or restrict the PU flow in other parts. The unique look could then be reinforced with different upper types or/and zonings of a customized knit structure.

(30) In the exemplary cut shown in FIG. 2E, the first region 19d of the upper 11 extends from the fourth exemplary first position 20d to 4 mm below the first position.

(31) The upper 11 shown in FIGS. 2A-E may be produced by any method disclosed herein using a mold 21 as disclosed herein.

(32) FIG. 3 shows another exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises an upper 11; an injection-molded region comprising a resin, wherein the resin at least partly coats an outer surface of the upper 11, wherein the resin coating 12 ceases at a first position 20, and wherein a thickness of the resin coating 12 increases gradually, in at least a first region of the upper 11. The resin is for forming a sole element 13 and additionally acts as a coating 12 applied on the upper 11.

(33) In this example, a thickness of the resin coating 12 increases gradually also along a lateral direction 40 at least in a toe region of the upper. In addition, a thickness of the resin coating 12 increases gradually along a height in the toe region of the upper and a lateral region of the shoe upper, beginning just behind the toe region.

(34) As can be seen from FIG. 3, the injection-molded region, comprising the resin coating 12 and the sole element 13 is devoid of any pinching.

(35) The exemplary upper 11 is weft knitted. In this example, a wale direction 30 is arranged substantially perpendicular to a longitudinal direction of the upper 11 in a least a fourth portion 37 of the upper 11. A channel 14a is formed between adjacent wales in the fourth portion 37. Therefore, the pressurized molten resin may flow in a controllable manner in the fourth portion 37 within the channel 14a during the injection molding, allowing a desired amount of flashing further, i.e. preventing unintended flashing.

(36) Additionally, a course direction 29 is arranged substantially perpendicular to a longitudinal direction of the upper 11 in a least a fifth portion 38 of the upper 11. A channel 14b is formed between adjacent wales, arranged substantially perpendicular to the course direction, in the fifth portion 38. Therefore, the pressurized molten resin cannot flow easily into the channel 14b during the injection molding, since the walls on the edges of the channel 14b may prevent flow into the channel, reducing the amount of unintended flashing further.

(37) It is therefore possible to create a fourth portion 37 with deliberate, controlled amount of coating but not indeliberate flashing and a fifth portion 38 with little or no flashing. In this example, the fourth portion is located in a toe region while the fifth portion is located in a lateral region of the shoe upper, beginning just behind the toe region.

(38) FIG. 4 shows another exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises an upper 11; an injection-molded region comprising a resin, wherein the resin at least partly coats an outer surface of the upper 11, wherein the resin coating 12 ceases at a first position 20, and wherein a thickness of the resin coating 12 increases gradually, in at least a first region of the upper 11. The resin is for forming a sole element 13 and additionally acts as a coating 12 applied on the upper 11.

(39) The exemplary upper 11 is weft knitted. A course direction 29 is arranged substantially perpendicular to a longitudinal direction of the upper 11 in a least a fifth portion 38 of the upper 11. Therefore, a wale direction 30 is arranged substantially parallel, i.e. between 0 to 30°, to a longitudinal direction of the upper 11 in a least the fifth portion 38 of the upper 11. A channel 14b is formed between adjacent wales, arranged substantially perpendicular to the course direction, in the fifth portion 38. Therefore, the pressurized molten resin cannot flow easily into the channel 14b during the injection molding, since the walls on the edges of the channel 14b may prevent flow into the channel, reducing the amount of unintended flashing further. However, as can be seen from FIG. 4, the amount of coating can still be controlled and a coating 12a may, for example, form a pocket. In this example, the fifth portion 38 is arranged in a lateral region of the upper just ahead of a heel region.

(40) FIG. 5 shows a schematic of another exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises an upper 11; an injection-molded region comprising a resin, wherein the resin at least partly coats an outer surface of the upper 11, wherein the resin coating ceases at a first position, and wherein a thickness of the resin coating increases gradually, in at least a first region of the upper 11. The resin is for forming a sole element 13 and additionally acts as a coating applied on the upper 11.

(41) The exemplary upper 11 is weft knitted. Knitted loops are indicated with reference sign 28. A wale direction 30 is arranged substantially perpendicular to a longitudinal direction of the upper 11 in a least a fourth portion 37 of the upper 11. A channel 14 is formed between adjacent wales in the fourth portion 37. Therefore, the pressurized molten resin may flow in a controllable manner in the fourth portion 37 within the channel 14 during the injection molding. This is illustrated by the vertical arrows.

(42) FIG. 6A shows a cross-section of a mold 21 according to the present invention comprising: a side wall 25 forming a cavity for receiving a shoe upper 11, wherein the side wall 25 is configured to contact the upper 11 at a contacting point 24 and wherein, after injecting a pressurized molten resin into the mold 21, there is a gap 22 filled with the resin between a side wall 25 of the mold 21 and an outer surface 17 of the upper 11, wherein the gap 22 is essentially zero at a contacting point 24, wherein the gap 22 increases gradually from the contacting point 24, in at least a first region 39 of the mold 21; and at least a first injection channel 23 for injecting a pressurized molten resin.

(43) Another way of describing the shape of the mold 21 according to the present invention is to say that a bite line of the mold is not a narrow sharp line, unlike in conventional molds, but instead, the bite line is relatively flat and gradually sloping.

(44) An upper 11 is arranged on a last (not shown separately) and placed inside the mold 21. The cavity comprises both the gap 22 and the upper 11 arranged on a last.

(45) The gap 22 increases by less than 1 mm per mm of a distance from the contacting point 24 in at least the first region of the mold 21, wherein the distance is measured along the outer surface of the upper 11. The distance is a height determined from the contacting point 24 towards a bottom region of the upper 11.

(46) The first region 39 of the mold 21 is arranged at least 2 cm above a floor 26 of the cavity, with respect to the orientation of the shoe upper 11.

(47) In this example, the side wall 25 of the mold 21 has a substantially convex shape. The side wall 25 may have a texture in order to impart a texture on the resin, although in this case, the side wall 25 does not comprise a texture. The mold 21 comprises a first part 27a and a second part 27b and the first part 27a and the second part 27b are joined in a heel and a toe region.

(48) The first injection channel 23 is arranged in a heel region of the mold 21. The first injection channel 23 is arranged underneath the upper 11, in a heel region.

(49) The mold 21 may further comprise at least a second injection channel, although in this example, there is only a single injection channel 23.

(50) The resin may be produced by the reaction of one or more compositions in the mold. For example, the resin may comprise a polyurethane and be produced by injecting a polyol into the mold at a temperature of about 35° C. and further injecting an isocyanate into the mold at a temperature of about 50° C. The polyol and isocyanate undergo an exothermic reaction forming polyurethane and may raise the temperature of the mold, for example to about 60° C. In this case, foaming of the polyol and the isocyanate may be the main source of pressure around the contacting point 24, where the pressure due to the injection pressure of the polyol and the isocyanate may be negligibly small.

(51) FIG. 6B in contrast shows a cross-section of a mold 31 as known in the art. A difference between a mold 31 as known in the art and a mold 21 according to the present invention is that at a contacting point 34, the gap 22 does not increase gradually from the contacting point 34. Instead, the contacting point 34 defines a sharp boundary with the disadvantages described herein.

(52) FIG. 6C shows how a mold 21 as shown in FIG. 6A may be opened. The mold 21 may be opened by moving the first part 27a and the second part 27b in opposite directions along a left 36a and a right 36b sideways direction. Geometrically, this arrangement is advantageous since it allows a great variety of shapes to be molded, for example so-called “undercuts” 35, which would not be possible for some alternative mold layouts, e.g. a mold where a top and a bottom portion are moved relative to each other to open the mold, as the mold will get stuck while being opened on an area of the sole element that is projecting outwards. An undercut may, for example, be part of a ground-engaging profile of a shoe and may improve the grip of a sole.

(53) FIG. 6D illustrates an aspect of a method according to the present invention. FIG. 6D shows a cross-sectional outline of an upper, arranged on a last 43. The last 43 is in tight contact with an inner surface of the upper. According to this exemplary aspect, closing the mold causes the upper to be compressed. In other words, the mold is smaller than the lasted upper. The solid line 41 indicates an outer surface of the upper when the upper is not compressed. The dotted line 42 indicates the outer surface of the upper, when the upper is compressed by the mold, prior to injection of the resin. Therefore, the dotted line 42 indicates essentially also the side wall of the mold for this cross-sectional cut. An uncompressed thickness of the upper is the distance between the surface of the last 43, since the upper is tightly arranged on the last 43, and the outer surface 41 of the uncompressed upper. A compressed thickness of the upper is the distance between the surface of the last 43 and the outer surface 42 of the compressed upper.

(54) The compression distance is the distance between the uncompressed outer surface and the compressed outer surface of the upper, since the inner surface of the upper is arranged tightly on an essentially incompressible last 43. The material of the upper is compressed by a first compression distance 48 in a first part 44 of the upper and a second compression distance 49 in a second part 46 of the upper, wherein the first compression distance 48 is smaller than the second compression distance 49.

(55) The first part 44 of the upper is arranged in a toe region 44. A similar compression is effected in a heel region 45. The second part 46 of the upper is arranged in a medial region 46. The upper is compressed by a third compression distance in a lateral region 47 of the upper, wherein the third compression distance is greater than the first compression distance 48 but smaller than the second compression distance 49. In this example, the first compression distance 48 is 0.3 mm, the second compression distance 49 is 1 mm and the third compression distance is 0.5 mm.

(56) FIG. 7A shows an exemplary shoe 50 comprising an upper 51 as known in the art. The shoe 50 further comprises a sole. The sole 53 is injection molded and displays a pinching effect 52 wherein some resin is pinched, in this example in the forefoot area, between separate parts of the mold during the molding process. The resulting pinching has an un-attractive visual appearance and presently needs to be removed manually.

(57) FIG. 7B shows another view of the exemplary shoe 50 of FIG. 7A. The upper 51 displays a flashing effect 54, which is an undesired spillover of the resin into areas of the upper where it is not desired. During injection molding, the resin crept into parts of the upper 51 unintentionally, giving the upper a defective and unclean look.

(58) FIG. 8 shows another exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises an upper 11, which is weft-knitted and coated by a coating 12 comprising a resin by a method according to the present invention. A plurality of channels 14 is formed in the knitted structure, of which an exemplary two channels are indicated with reference numeral 14. The channels 14 are one example of a knit-opening 61 which is at least partially filled by resin. The exemplary article of footwear 10 also comprises a sole element 13, comprising a rear part 13b and a front part 13a, wherein the front part 13a is formed by the resin, i.e. the resin comprised in the coating 12.

(59) FIG. 9 shows another exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises an upper 11, which is also weft-knitted and coated by a coating 12 comprising a resin by a method according to the present invention. A plurality of channels 14 is formed in the knitted structure in-between strongly pronounced ribs 62. An exemplary two channels are indicated with reference numeral 14 and an exemplary two ribs are indicated with reference numeral 62. The channels 14 are one example of a knit-opening 61 which is at least partially filled by resin. FIG. 9 shows an example of how the resin may adapt to the knitted structure. Part of the ribs 63 is also coated by the resin. However, the structure of the coated ribs 63 is still visible through the coating 12. A thickness of the resin coating is sufficiently thin for the knitted structure of the ribs 63 to remain visible through the resin coating.

(60) FIG. 10 shows another exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises an upper 11, which is weft-knitted and coated by a coating 12 comprising a resin by a method according to the present invention. A plurality of knit-openings 61 is formed in the knitted structure. The knit-openings 61 are partial holes. Some knit-openings 64 are coated by the resin. The resin thus takes a pattern of the knitted upper 11, i.e. visually replicating the texture of the knitted upper 11. The exemplary article of footwear 10 also comprises a sole element 13, comprising the resin.

(61) FIG. 11 shows another exemplary article of footwear 10 according to the present invention. The article of footwear 10 comprises an upper 11, which is weft-knitted and coated by a coating 12 comprising a resin by a method according to the present invention. An edge 65 of the coating is essentially flush with an outer surface of the upper. The exemplary article of footwear 10 also comprises an outsole 16, which is not formed with the resin but instead attached in a separate step.

(62) Some embodiments described herein relate to method of producing an article of footwear comprising providing an upper; providing a mold and opening the mold; inserting the upper into the open mold; closing the mold; and injecting a pressurized molten resin, wherein, after the injecting, there is a gap filled with the resin between a side wall of the mold and an outer surface of at least a first portion of the upper, wherein the gap is essentially zero at a contacting point, wherein the gap increases gradually from the contacting point in at least a first region of the mold.

(63) In any of various embodiments described herein, the side wall of the mold has a substantially convex shape.

(64) In any of various embodiments described herein, the material of the upper is compressed by a first compression distance in a first part of the upper and a second compression distance in a second part of the upper, wherein the first compression distance is smaller than the second compression distance, wherein the first part of the upper is arranged in a heel or a toe region and the second part of the upper is arranged in a lateral or a medial region of the upper.

(65) In any of various embodiments described herein, the mold comprises at least a first part and a second part, and wherein the first part and the second part are joining in a heel region and a toe region.

(66) In any of various embodiments described herein, wherein the mold further comprises at least a first injection channel for injecting the pressurized molten resin, and wherein the first injection channel is arranged in a heel region of the mold.

(67) In any of various embodiments described herein, the mold further comprises at least a second injection channel

(68) In any of various embodiments described herein, the upper is warp-knitted or weft-knitted

(69) In any of various embodiments described herein, the method further comprises at least partially filling at least one knit-opening in the warp-knitted or weft-knitted upper with the resin.

(70) In any of various embodiments described herein, the resin forms at least a part of a sole element of the article of footwear, wherein the sole element is a midsole of the article of footwear.

(71) In any of various embodiments described herein, the resin forms at least a part of a sole element of the article of footwear, wherein the sole element is the entire sole of the article of footwear.

(72) Some embodiments described herein relate to a mold for producing an article of footwear comprising a side wall forming a cavity for receiving a shoe upper, wherein the side wall is configured to contact the upper at a contacting point and wherein, after injecting a pressurized molten resin into the mold, there is a gap filled with the resin between a side wall of the mold and an outer surface of the upper, wherein the gap is essentially zero at the contacting point, wherein the gap increases gradually from the contacting point, in at least a first region of the mold; and at least a first injection channel for injecting a pressurized molten resin.

(73) In any of various embodiments described herein, the mold further comprising at least a second injection channel.

(74) Some embodiments described herein relate to an article of footwear comprising: an upper; an injection-molded region comprising a resin, an injection-molded region comprising a resin, wherein the resin coating ceases at a first position, and wherein a thickness of the resin coating increases gradually, in at least a first region of the upper.

(75) In any of various embodiments described herein, the resin forms a sole element of the article of footwear.

(76) In any of various embodiments described herein, the resin forms a sole element of the article of footwear, wherein the sole element is a midsole of the article of footwear.

(77) In any of various embodiments described herein, the resin forms a sole element of the article of footwear, wherein the sole element is the entire sole of the article of footwear.

(78) In any of various embodiments described herein, wherein the injection-molded region is devoid of any pinching.

REFERENCE SIGNS

(79) 10: article of footwear 11: upper 12: coating 13: sole element 14: channel 15: tongue 16: outsole 17: outer surface of the upper 18: surface of the coating 19: first region of the upper 20: first position 21: mold 22: gap 23: injection channel 24: intersection point 25: side wall 26: floor 27a: first part 27b: second part 28: loop 29: course direction 30: wale direction 31: mold as known in the art 34: intersection point for mold as known in the art 35: undercut 36: sideways direction 37: fourth portion 38: fifth portion 39: first region of the mold 40: lateral direction 41: uncompressed outer surface of upper 42: compressed outer surface of upper 43: last 44: toe region 45: heel region 46: medial region 47: lateral region 48: first compression distance 49: second compression distance 50: conventional shoe 51: conventional upper 52: pinching 53: conventional sole 54: flashing 61: knit-opening 62: rib 63: coated rib 64: coated knit-opening 65: edge