An article of footwear with adhesive-free attachments
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-07
- Publication Date
- 2026-03-25
AI Technical Summary
Conventional footwear construction methods using adhesives or stitches are prone to durability issues due to aging, require costly and complex manufacturing processes, and hinder recycling, as adhesives break down over time and stitching is time-consuming and expensive.
An article of footwear with an adhesive-free design where the outer sole is stretched over the insole to sandwich the upper, utilizing upstanding walls and engaging features like ridges and valleys for secure engagement without adhesives or stitching, facilitating easy assembly, disassembly, and recycling.
This design provides a durable, cost-effective, and easily recyclable footwear solution that maintains structural integrity without adhesives or stitching, ensuring secure attachment and easy resoling while reducing manufacturing complexity and environmental impact.
Smart Images
Figure GB2024051189_21112024_PF_FP_ABST
Abstract
Description
[0001] AN ARTICLE OF FOOTWEAR WITH ADHESIVE-FREE ATTACHMENTS
[0002] FIELD OF THE INVENTION
[0003] The present invention relates to an article of footwear. In particular, the present invention relates to an article of footwear with adhesive-free attachments.
[0004] BACKGROUND
[0005] Articles of footwear, such as shoes, boots, slippers, sandals, and the like, are generally composed of two primary elements: an upper that secures a footwear to the foot of a wearer; and a sole structure comprising at least an insole and an outer sole, that provides support underneath.
[0006] An article of footwear typically has a glue or an adhesive that attaches the insole to the outer sole. Alternatively, stitches are used to stitch an upper, the insole and the outer sole together in order to have an adhesive-free attachment.
[0007] However, there are problems associated using such attachments. For example, the adhesives used in a footwear construction can break down due to ageing, especially when exposed to ultraviolet light and moisture for a long time, leading to separation of the outer sole from the upper. This can result in footwear that is less durable and may require frequent repairs or replacement. Moreover, the adhesives are chemical compounds which may necessitate production with limited human exposure during the time of application; this can increase the cost and complexity of manufacture. Further, using stitches for the attachment of the insole and the outer sole is time-consuming and can be expensive as the stitching requires more time and advanced equipment to execute correctly. Finally, it is more difficult for users to separate footwear into its individual components for recycling.
[0008] It is an object of the present invention to address above problems. SUMMARY OF INVENTION
[0009] According to an aspect of the invention, there is provided an article of footwear. The article of footwear comprising an upper and an insole received within the upper. The article of footwear further comprising an outer sole configured to receive the insole and at least a portion of the upper, wherein upstanding walls of the outer sole are stretched over the upper where it receives the insole in order to sandwich the upper between an inner surface of the outer sole and an outer surface of the insole.
[0010] In this way, an article of footwear is achieved which does not require any glue or stitching for the construction. The outer sole is stretched over the insole which makes it easy to assemble or disassemble the article as compared to conventional articles which are glued or stitched. The sandwiching of the upper between the stretched outer sole and the insole retains the upper in the intended position, thereby keeping the article of footwear intact while in use without requiring any adhesive or stitched construction. The easy assembly and disassembly of the article of footwear facilitates easy recycling and easy resoling of the article. The stretching of the outer sole means that it applies a compression force to the upper with the insole received within, and this is enough to secure all of the elements together for normal use.
[0011] Preferably, the insole comprises a top surface and a bottom surface, opposite to the top surface, and wherein the outer surface extends around the perimeter of the insole, between the top surface and the bottom surface of the insole. This provides a secure connection between the outer sole and the upper and insole because the outer sole is secured around the full perimeter of the insole.
[0012] The insole may be in different shapes and may comprise a solid or a hollow structure inside. In one example, the outer surface of the insole may include upright walls which allows the insole to be cupped from inside. The upright walls further allow for use of a thicker looking sole structure while still having a low profile. Preferably, the walls of the outer sole are stretched so that they are hooked onto the upper and insole. Further, the upper is sandwiched at least partly between the outer sole and an upward facing surface of the insole.
[0013] The upward facing surface is preferably on the top surface of the insole. However, the upward facing surface may be defined in a notch that is between the top and bottom surfaces of the insole. The upward facing surface preferably has a normal vector that extends at least partly in a vertical direction, in normal use.
[0014] Preferably, the outer surface of the insole between the top surface and the bottom surface comprises an outward bulge. The bulbous shape of the outer surface of the insole results in an additional stress acting on the outer sole when the outer sole is stretched over the insole. This provides a force acting on the insole which allows the outer sole to tightly grip the upper.
[0015] Preferably, the bulge provides a flared shape for the insole in which, at some point, it widens from the top surface towards the bottom surface. In a similar manner, the flared shape of the outer surface of the insole allows the outer sole to tightly sandwich the upper, thereby avoiding the upper from separation during use.
[0016] Preferably, before assembly, the total length of a boundary or perimeter at a top edge of the outer sole is shorter than the total length of the boundary or perimeter of the top surface the insole. In this way, the outer sole is configured to apply an inward compressive force towards the insole when it is stretched over, which allows the outer sole to grip the upper. Additionally, when a user walks, the shorter total length of the top edge helps to ensure that the outer sole remains in position. Thus, the above configuration of the top edge of the outer sole results in a strong and a glue-less construction of an article of footwear.
[0017] The article of footwear of further comprising engaging features on the inner surface of the outer sole and corresponding engaging features on the outer surface of the insole. The engaging features further aid in stretching of the outer sole over the insole by providing an increased frictional surface between the outer sole and the insole when the article of footwear is in use, which keeps the outer sole engaged with the insole, thereby improving the sandwiching of the upper between the outer sole and the insole.
[0018] Preferably, the engaging features comprise ridges and valleys which are configured to coordinate with each other for engaging the inner surface of the outer sole and the outer surface of the insole. The coordination of the ridges and valleys of the engaging features allow surfaces of the outer sole and the insole to engage with each other. More specifically, the ridges slide inside the valleys which lock the slides and valleys together. The locking of the ridges and valleys enhances the engagement of the surfaces of the outer sole and the insole, which in turn further improves the stretch of the outer sole over the insole.
[0019] Preferably, the ridges are present on the inner surface of the outer sole and the valleys are present on the outer surface of the insole. Alternatively, the ridges are present on the outer surface of the insole and the valleys are present on the inner surface of the outer sole. The ridges and valleys could be constructed from the same material as of the outer sole and the insole. Moreover, the ridges and valleys do not require any additional adhesive or stitching to engage with each other. Thus, the engaging portions having the ridges and valleys, provide an easy and effective adhesive-free construction of the article of footwear. The ridges and valleys could be aligned substantially vertically or horizontally, in normal use. Alternatively, the ridges and valleys could be aligned in any orientation which allows the ridges and valleys to lock together.
[0020] Preferably, the upper is a tubular knit or a traditional strobal, or an alternative fabrication that allows for coverage of the foot and provides enough material to pass under the insole. In this way, a soft and closed upper is provided which gets sandwiched effectively between the outer sole and the insole. Further, the upper as constructed in this way is easy to be held in the sandwiched position between the outer sole and the insole, thereby making the adhesive-free construction of the article of footwear more effective. BRIEF DESCRIPTION OF DRAWINGS
[0021] Embodiments of the invention are now described, by way of example, with reference to the drawings, in which:
[0022] Figure 1A is a schematic cross-sectional side view of an article of footwear, in an embodiment of the present invention;
[0023] Figure 1 B is a close-up view of a rear section of the article of footwear of Figure 1A;
[0024] Figure 1 C is a close-up view of a sole structure of the article of footwear of Figure 1A;
[0025] Figure 2 is another schematic cross-sectional side view of an article of footwear, in another embodiment of the present invention;
[0026] Figure 3 is a close-up cross-sectional view of another sole structure of an article of footwear, in another embodiment of the present invention; and
[0027] Figures 4-8 are other schematic cross-sectional side views of an article of footwear, in other embodiments of the present invention.
[0028] DETAILED DESCRIPTION
[0029] Figure 1 A provides a schematic cross-sectional side view of an article of footwear 100, in an embodiment of the present invention. The article of footwear 100 comprises a foot-receiving upper 102 provided with a sole structure 104. The sole structure 104 comprises an outer sole 106 and an insole 108.
[0030] Typically, the upper 102 is constructed as a sock which is configured to receive the insole 108 within an interior void that will also receive a user’s foot. The upper 102 may be fabricated from any one or combination of a variety of materials, such as textiles, engineered foams, polymers, natural and synthetic leathers, and the like. In one example, the upper 102 may be a tubular knit or a traditional strobal. In another example, the upper 102 may include an alternative fabrication that allows for coverage of the foot and provides enough material to pass under the insole 108. The insole 108 generally has a greater stiffness than the upper 102, and it gives the upper shape and structure when it is received within.
[0031] During assembly the insole 108 is fitted into the upper 102 so that it is received within the interior void. The insole 108 is operatively located at a lower portion of the upper 102, such that the insole 108 abuts the sole of the foot and acts as a bed for the foot of a wearer. The insole 108 may incorporate one or more materials or embedded elements that enhance the comfort, performance, and / or ground- reaction-force attenuation properties of the article of footwear 100.
[0032] The outer sole 106 is stretched over the insole 108 so that the insole 108 and at least a portion of the upper 102 are received within the outer sole 106. The outer sole 106 may be formed from a natural or synthetic rubber material that enables stretching of the outer sole 106 whilst also providing a durable and wear-resistant bottom surface 110 for contacting the ground. The bottom surface 110 may additionally be contoured and textured to enhance the traction properties between the article of footwear 100 and the ground. The insole 108 is made from a material that resists deformation when it is compressed by the outer sole 106 that is stretched around it.
[0033] When the outer sole 106 receives the insole 108 and at least the portion of the upper 102, upstanding walls 112 of the outer sole 106 are stretched over the upper 102 where it receives the insole 108. In Figure 1 the upstanding walls 112 are shown at the front and rear of the shoe. However, Figure 1 is a cross-sectional view and the upstanding walls are in fact provided around the full perimeter of the article of footwear 100. Thus, the upstanding walls 112 will generally extend between points A and B so that they can hook onto the insole 108 and grip an upward facing surface 120 (shown in figure 1 B and described in detail below).
[0034] In this way, the upper 102 is squeezed between an inner surface of the outer sole 106 and an outer surface 118 of the insole 108. Due to stretching of the upstanding walls 112, a spring force is applied by the upstanding walls 112 towards the insole 108. This allows the outer sole 106 to grip the upper 102 with the relatively rigid insole 108 inside. The upstanding walls 112 of the outer sole 106 extend upwards from the bottom surface 110 of the outer sole 106, and an inner surface of the upstanding walls 112 is the inner surface of the outer sole 106.
[0035] The insole 108 comprises a top surface 114 and a bottom surface 116 which is opposite to the top surface 114.
[0036] An outer surface 118 of the insole 108 extends around the perimeter of the insole 108, between the top surface 114 and the bottom surface 116. Accordingly, when the insole 108 which has been received by the upper 102, and is further received by the outer sole 106, the upper 102 comes into contact with the outer surface 118 of the insole 108 on one side and with the inner surface of the outer sole 106 on the other side. This squeezes the upper 102 between the stretched outer sole 106 and the relatively rigid insole 108.
[0037] The upstanding walls 112 of the outer sole 106 are stretched so that they are hooked onto the upper 102 and the insole 108. The upstanding walls of the outer sole 106 are stretched so that the upper 102 is sandwiched partly between the outer sole 106 and an upward facing surface 120 of the insole 108. As illustrated in figure 1 B, the upward facing surface 120 of the insole 108 is on the outer surface 118 of the insole. Alternatively, the upward facing surface 120 may at least be partly on the top surface 114. The upward facing surface 120 preferably has a normal vector, V1 , that extends at least partly in a vertical direction, in normal use. Thus, the upward facing surface 120 is at a certain angle with respect to the top surface 114 and the outer surface 118 of the insole 108. However, the upward facing surface 120 may also be at a same angle as of the top surface 114 or the outer surface 118. The upstanding walls 112 are stretched at least on to the upward facing surface 120 so that a spring force resulting from the stretching of the upstanding walls 112 has a component in a direction opposite to the vector V1 , thereby resulting in a tight gripping of the upper 102 between an inner surface of the outer sole 106 and the upward facing surface 120.
[0038] The outer sole 106 comprises a top edge 122 which hooks to the upper 102 and the upward facing surface 120 of the insole 108, thereby allowing the upstanding walls 112 to hook onto the upper 102 and the insole 108. The perimeter of the top surface 114 of the insole 108 defines a boundary of the top surface 114 of the insole 108 and the perimeter of the outer sole 106 defines a boundary of a top edge 122 of the outer sole 106.
[0039] Before the article of footwear 100 is assembled, the outer sole 106 is in an unstretched configuration. In this configuration, the total length of the boundary of the top edge 122 of the outer sole 106 is shorter than the total length of the boundary of the top surface 114 of the insole 108. When the article of footwear 100 is assembled, the outer sole 106 is stretched over the upper 102 and the insole 108, thereby leading the outer sole 106 to be in a stretched configuration. In this configuration, the total length of the boundary of the top edge 122 of the outer sole 106 is greater than the total length of the boundary of the top surface 114 of the insole 108.
[0040] However, due to the shorter total length of the boundary of the top edge 122 in the unstretched configuration, a biasing force is applied towards the upward facing surface 120 of the insole 108 in the stretched configuration. The application of the biasing force causes the top edge 122 to hook onto the upward facing surface 120. Additionally, when a wearer of the article of footwear 100 walks, the shorter total length of the boundary of the top edge 122 stops the outer sole 106 from disassembling which in turn stops the sandwiched upper 102 from getting loose and come out of the gripped position.
[0041] As shown in figure 1 C, the outer surface 118 around the perimeter between the top surface 114 and the bottom surface 116 of the insole 108 comprises an outward bulge 124. In figure 1 C, the outward bulge 124 is shown at the front and rear of the article of footwear 100. However, figure 1C is a cross-sectional view and the outward bulge 124 is in fact provided around the full perimeter of the outer surface 118 of the insole 108. The outward bulge 124 of the outer surface 118 results in an additional stress being acting on the upstanding walls 112 when the upstanding walls 112 are stretched over the insole 108. The additional stress acting by virtue of the stretch over the bulge 124 results in a restoring force acting towards the insole 108 which urges the outer sole 106 inwards to tightly grip the upper 102 between the insole 108 and the outer sole 106.
[0042] The bulge 124 can be of any shape, such as a convex shape or a flared shape. In one example, the bulge 124 provides a flared shape for the insole 108 in which it widens from the top surface towards the bottom surface, as shown in figure 6.
[0043] Figure 2 provides another schematic side view of an article of footwear 200, in another embodiment of the present invention. The article of footwear 200 is same as the article of footwear 100 as described above. Additionally, in the present embodiment, the article of footwear further comprises engaging features 202 which further aid in sandwiching or gripping of the upper 102 between the outer sole 106 and the insole 108.
[0044] The engaging features 202 comprises a first set of engaging features present on the inner surface of the outer sole 106 and a corresponding second set of engaging features present on outer surface of the insole 108. The first set of engaging features comprises ridges 206 and the second set of engaging features comprises valleys 204, wherein the ridges 206 and valleys 204 coordinate with each other for engaging an inner surface of the outer sole 106 and the outer surface 118 of the insole 108. The ridges 206 slide inside the valleys 204 which lock the ridges and valleys together.
[0045] In one example, the ridges 206 are present on the inner surface of the outer sole 106 and valleys 204 are present on the outer surface 118 of the insole 108. Alternatively, the ridges 206 can be present on the outer surface 118 of the insole 108 and valleys 204 can be present on the inner surface of the outer sole 106.
[0046] Figure 3 is a close-up cross-sectional view of another sole structure 304 of an article of footwear 300, in another embodiment of the present invention. The article of footwear 300 is same as the article of footwear 100 as described above. However, in the present embodiment, the sole structure 304 includes an insole 308 having upright walls 302. The upright walls 302 are extending around the perimeter of the insole 308, defining an enclosed space between the upright walls 302. The enclosed space has a floor which is at a lower level relative to the height of the upright walls 302 which provides the insole 308 cupped shape from inside. The upright walls 302 further allow for use of a thicker looking sole structure 104 while still having a low profile. The insole 308 comprises an outer surface 318 having an outward bulge 324 having a convex shape.
[0047] Figure 4 provides another schematic cross-sectional side view of an article of footwear 400, in another embodiment of the present invention. The article of footwear 300 is same as the article of footwear 100 as described above. However, in the present embodiment, an insole 408 comprises an outer surface 418 having a convex shaped outward bulge 424 which is smaller in size at a rear portion of the article of footwear 400 as compared to a front portion.
[0048] Figure 5 provides another schematic cross-sectional side view of an article of footwear 500, in another embodiment of the present invention. The article of footwear 500 is same as the article of footwear 100 as described above. However, in the present embodiment, an insole 508 has a different shape than the insole 108 of the article of footwear 100 and does not include a sunken top surface. The insole 508 has a thicker structure and has a uniform outward bulge 524 all around the perimeter. However, in one example, the insole 508 may be provided with half the thickness, as shown in figure 5 The thicker insole 508 leads to the use of a thicker outer sole 506 which is stretched over the insole 508. Further, the sidewalls on the thicker insole 508 are an option if aesthetically a cup sole effect with the foot sunken has to be provided to create a lower profile whilst still maintaining high walls of the thicker outer sole 506.
[0049] Figure 6 provides another schematic cross-sectional side view of an article of footwear 600, in another embodiment of the present invention. The article of footwear 600 is same as the article of footwear 100 as described above. However, in the present embodiment, an insole 608 comprises an outer surface 618 having an outward bulge 624 which provides a flared shape to the insole 608 in which it widens from a top surface 614 towards a bottom surface 616. Figure 7 provides another schematic cross-sectional side view of an article of footwear 700, in another embodiment of the present invention. The article of footwear 700 is same as the article of footwear 100 as described above. However, in the present embodiment, an insole 708 comprises an outer surface 718 having an outward bulge 724 which includes a notch.
[0050] Figure 8 provides another schematic cross-sectional side view of an article of footwear 800, in another embodiment of the present invention. The article of footwear 800 is same as the article of footwear 100 as described above. However, in the present embodiment, an insole 808 comprises an outer surface 818 having an outward bulge 824 which provides a square ended shape to the insole 808. As shown in the figure, the insole 808 is having sharp comers on a top surface 814 and a bottom surface 816, joined by a straight line. In the present embodiment, an upward facing surface 820 is at a same angle as of the top surface 814.
Claims
CLAIMS1 . An article of footwear comprising: an upper; an insole received within the upper; and an outer sole configured to receive the insole and at least a portion of the upper, wherein upstanding walls of the outer sole are stretched over the upper where it receives the insole in order to sandwich the upper between an inner surface of the outer sole and an outer surface of the insole, wherein the insole comprises a top surface and a bottom surface, opposite to the top surface, and wherein the outer surface extends around the perimeter of the insole, between the top surface and the bottom surface of the insole, and wherein the total length of a boundary at a top edge of the outer sole is shorter than the total length of the boundary of the top surface the insole.
2. The article of footwear of any one of the preceding claims, wherein the walls of the outer sole are stretched so that they are hooked onto the upper and the insole.
3. The article of footwear of claim 2, wherein the upper is sandwiched at least partly between the outer sole and an upward facing surface of the insole.
4. The article of footwear of any of claims 1 to 3, wherein the outer surface of the insole between the top surface and the bottom surface comprises an outward bulge.
5. The article of footwear of any one of the preceding claims, further comprising engaging features on the inner surface of the outer sole and corresponding engaging features on the outer surface of the insole.
6. The article of footwear of claim 5, wherein the engaging features comprise ridges and valleys which are configured to coordinate with each other for engaging the inner surface of the outer sole and the outer surface of the insole.
7. The article of footwear of claim 6, wherein the ridges are present on the inner surface of the outer sole and the valleys are present on the outer surface of the insole.
8. The article of footwear of claim 6, wherein the ridges are present on the outer surface of the insole and the valleys are present on the inner surface of the outer sole.
9. The article of footwear of any one of the preceding claims, wherein the upper is a tubular knit.
10. The article of footwear of any one of claims 1-8, wherein the upper is a traditional strobal.11 . The article of footwear of any one of claims 1 -8, wherein the upper is an alternative fabrication that allows for coverage of the foot and provides enough material to pass under the insole.