GEL INSOLE

Abstract

An insole for insertion into footwear, comprising a forefoot portion, a midfoot portion and a heel portion; the midfoot portion connecting together the forefoot portion and the heel portion; said insole comprising a cushioning layer of a viscoelastic gel material which provides a cushioning function; and wherein the midfoot portion and the heel portion comprise a peripheral edge that curves upwards.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to shoe insoles or inserts, and more particularly, to gel insoles particularly adapted to provide greater stability within a shoe and to provide greater support to the wearer.

Various types of insoles are known which fit within shoes in order to correct various foot problems, alleviate pain and otherwise provide more comfort to the wearer. Examples of such insoles are those sold by the assignee of the present invention under the trademark Dr. SCHOLL'S®, in particular those comprised of gel materials as described and claimed in U.S. Pat. No. 6,598,321.

However, it would be useful and desirable to have a full length insole formed of gel material that includes an upwardly curved edge that contacts the outside edge of the foot without constricting the forefoot. In particular, it would be useful and desirable to construct such a full length insole where the upwardly curved edge begins at a point behind where the ball of the foot contacts the insole, so as to assist in maintaining contact between the foot and the insole and prevent side-to-side movement of the foot on the insole when pressure is exerted on the insole by the foot.

Because of the viscous nature of the gel, the gel insoles provide shock absorption and consequently protection to the foot. One reason that gel insoles are popular is that they can be made sufficiently thin to fit in shoes. The most common materials used for making gels are polyurethane, silicone, and thermoplastic rubber. However, because the materials used to make the gel insoles typically exhibit a high coefficient of friction upon final manufacture, the resulting insoles have a sticky feel at the surface. Although this property is beneficial on lower surfaces of insoles to keep them in place in shoes, a sticky top surface, which contacts the foot, interacts unfavorably with skin or hosiery materials. Fabric can be attached to the top surface of the gel material as a means to eliminate the problem. However, the additional step of adding the fabric adds cost to the process of making the insole. If a non-fabric coated gel insole is desired, the gel material can alternatively be dusted, usually with talc, to lower the amount of friction. However, the dusting method is a temporary solution, as the dusting material typically separates from the gel material after a prolonged period of use, leaving the sticky surface exposed. The dusting method also adds cost to the production of insoles.

Moreover it has been surprisingly discovered that an arch support insert comprising a gel material of a different hardness than the gel material of the remainder of the insert provides an improvement in arch support, shock absorption and overall comfort.

These and other objectives are satisfied by the invention described and claimed herein.

SUMMARY OF THE INVENTION

The present invention provides an insole for insertion into footwear, said insole comprising a forefoot portion, a midfoot portion and a heel portion; the midfoot portion connecting together the forefoot portion and the heel portion; said insole comprising a cushioning layer of a viscoelastic gel material which provides a cushioning function; and wherein the midfoot portion and the heel portion comprise a peripheral edge that curves upwards.

The invention also provides an insole for insertion into footwear comprising a forefoot portion, a midfoot portion and a heel portion; said insole comprising a cushioning layer of a viscoelastic gel material which provides a cushioning function; wherein at least one of the forefoot portion and heel portion comprising at least one substantially dome shaped pillow protruding from the cushioning layer; and wherein the insole comprises a peripheral edge that curves upwards at the midfoot portion and the heel portion.

In accordance with another aspect of the invention, the insole comprises a forefoot portion, a mid-foot portion, and a heel portion, said forefoot portion, mid-foot portion and heel portion being formed by a cushioning layer of a resilient material having a first hardness and which provides a cushioning function, and a cushioning insert comprised within a recess in said cushioning layer and extending down from said cushioning layer; said cushioning insert comprising a resilient material having a second hardness that is less than the hardness of said cushioning layer.

In accordance with another aspect of the present invention, an insole for insertion into footwear is provided which includes a forefoot portion, a mid-foot portion and a heel portion and has a cushioning layer having upper and lower surfaces; which cushioning layer comprises a first elastomeric gel material having a first hardness and within a recess in the bottom surface of the cushioning layer a second elastomeric gel material having a second hardness different from the hardness of the first elastomeric gel material, the second elastomeric gel material located substantially in the mid-foot portion to be positioned below the arch of the foot.

The insole of the invention is a full length insole formed from the forefoot portion, the heel portion and a mid-foot portion connecting together the forefoot portion and the heel portion. Preferably, the cushioning layer extends through the forefoot portion, heel portion and mid-foot portion. Preferably, at least one of the forefoot portion and heel portion includes at least one substantially dome shaped pillow protruding down from the cushioning layer thereat.

Preferably the cushioning layer and the pillow(s) are formed from the same viscoelastic gel material as a unitary, one-piece structure. In an alternative embodiment, the pillow(s) are formed from a foam material.

The insole further may comprise an arrangement for maintaining the insole in position in the footwear when the insole is in use. The arrangement can comprise, for example, an adhesive at a lower surface of the insole, for example a non-permanent adhesive that permits removal of the insole from the footwear and repositioning the insole in the footwear, or alternatively, a high friction lower surface of the insole.

In another embodiment, the arrangement for maintaining the insole in position includes a tackifier added to the gel material. Preferably, the gel material forming the dome shaped pillow(s) comprises a plurality of spaced apart spring walls formed from the viscoelastic gel, the spring walls extending from a lower surface of the cushioning layer. In one embodiment, the spring walls have a height which is greatest at a center of the pillow and which tapers in height toward edges of the pillow. Preferably, each of the spring walls is formed in a generally sinusoidal wave shape.

Preferably, the cushioning layer has a substantially uniform thickness of about 2 mm and the pillow(s) have a height less than about 3 mm above the uniform layer.

The invention further comprises a top cover which can be secured to an upper surface of the cushioning layer. Preferably the top cover is a made of a low friction film material, which preferably comprises a styrenic block copolymer.

The invention also provides a method for constructing a gel insole comprising a viscoelastic gel material to comprise a low friction top surface, which method comprises the steps of placing a film material comprising a styrenic block copolymer and having top and bottom surfaces in an injection mold, and injecting viscoelastic gel material into the mold to form the gel insole on the bottom surface of the film material, thereby providing the low friction top surface for the gel insoles.

The above and other features of the invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a left insole according to one embodiment of the present invention;

FIG. 2 is a top plan view of the left insole;

FIGS. 3A and 3B are bottom plan views of the left and right insoles, respectively, according to one embodiment;

FIG. 4 is a side elevational view of the right insole;

FIG. 5 is perspective view of one embodiment of a right insole showing combination of gel film top cover and cloth top cover;

FIG. 6 is top and bottom view of an embodiment of insoles showing first and second gels of different hardness;

FIG. 7 is perspective view of one embodiment of a right insole showing combination of gel film top cover and cloth top cover;

FIG. 8 is perspective view of one embodiment of a left insole showing combination of gel film top cover and cloth top cover.

DETAILED DESCRIPTION

Referring to the drawings in detail, and initially to FIGS. 1-4 thereof, a left insole 10 according to a first embodiment of the present invention is adapted to be placed in an article of footwear, as is well known. A right insole (depicted in FIG. 3B) is identical to left insole 10 and is a mirror image thereof.

As depicted in FIGS. 1 and 2, insole 10 is designed to fit the shape of a human left foot and therefore includes a curved toe or forefoot portion 12, a heel portion 14, and a mid-foot portion 16 which connects forefoot portion 12 and heel portion 14 together. Cushioning layer 18, preferably generally planar throughout most of the insole, curves upward at the peripheral edges of the midfoot portion 30 and heal portion 32 of the insole in order to create a cradle for the side, heel and arch of the foot.

In one embodiment shown in FIGS. 3A and 3B, insole 10 comprises a pillow 20 extending from the lower surface of cushioning layer 18 at forefoot portion 12 and a generally dome shaped, lower pillow 22 extending from the lower surface of cushioning layer 18 at heel portion 14. Preferably, pillows 20, 22 are generally dome shaped.

As depicted in FIG. 4, cushioning layer 18 and pillows 20 and 22 are formed as a unitary, one-piece layer of the same viscoelastic gel material. In an alternative embodiment, the pillows 20 and 22 are formed from a different material that the viscoelastic gel material of the cushioning layer 18. Specifically, in said alternative embodiment, pillows 20 and 22 can be made from a resilient foam material that provides a conventional cushioning function. As such, pillows 20 and 22 form a typical foam mechanical spring, shock absorption layer that cushions the foot, in order to decrease pressure. Cushioning layer 18 is preferably made from non-foam elastomers such as the class of materials known as viscoelastic gel polymers as described in U.S. Pat. No. 6,598,321, which show high levels of damping when tested by dynamic mechanical analysis performed in the range of −50° C. to 100° C. Because the mechanical properties of the gel are more viscous than elastic, the gel provides a high energy absorption. Gels that can be used according to the present invention are thermoplastic elastomers (elastomeric materials), such as materials made from many polymeric families, including but not limited to the Kraton family of styrene-olefin-rubber block copolymers, thermoplastic polyurethanes, thermoplastic poly olefins, polyamides, polyureas, polyesters and other polymer materials that reversibly soften as a function of temperature. The preferred elastomer is a Kraton block copolymer of styrene/ethylene-co-butylene/styrene or styrene/butadiene/styrene with mineral oil incorporated into the matrix as a plasticizer. In one embodiment, cushioning layer 18 can be a laminate construction, that is, a multilayered composite of any of the above materials. Multilayered composites are made from one or more of the above materials such as a combination of polyethylene vinyl acetate and polyethylene (two layers), a combination of polyurethane and polyvinyl chloride (two layers) or a combination of ethylene propylene rubber, polyurethane foam and ethylene vinyl acetate (3 layers).

When made of a different material than cushioning layer 18, pillows 20 and 22 can be made from any suitable material including, but not limited to, any flexible material which can cushion and absorb the shock from heel strike on the insole. Suitable shock absorbing materials can include any suitable foam, such as but not limited to, cross-linked polyethylene, poly(ethylene-vinyl acetate), polyvinyl chloride, synthetic and natural latex rubbers, neoprene, block polymer elastomer of the acrylonitrile-butadiene-styrene or styrene-butadiene-styrene type, thermoplastic elastomers, ethylenepropylene rubbers, silicone elastomers, polystyrene, polyurea or polyurethane; most preferably a polyurethane foam made from flexible polyol chain and an isocyanate such as a monomeric or prepolymerized diisocyanate based on 4,4′-diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI). Such foams can be blown with freon, water, methylene chloride or other gas producing agents, as well as by mechanically frothing to prepare the shock absorbing resilient layer. Such foams advantageously can be molded into the desired shape or geometry.

The materials of cushioning layer 18 and pillows 20 and 22 can be prepared by conventional methods such as heat sealing, ultrasonic sealing, radio-frequency sealing, lamination, thermoforming, reaction injection molding, and compression molding and, if necessary, followed by secondary die-cutting or in-mold die cutting. Representative methods are taught, for example, in U.S. Pat. Nos. 3,489,594; 3,530,489 4,257,176; 4,185,402; 4,586,273, in the Handbook of Plastics, Herber R. Simonds and Carleton Ellis, 1943, New York, N.Y., Reaction Injection Molding Machinery and Processes, F. Melvin Sweeney, 1987, New York, N.Y., and Flexible Polyurethane Foams, George Woods, 1982, New Jersey, whose preparative teachings are incorporated herein by reference. For example, the innersole can be prepared by a foam reaction molding process such as taught in U.S. Pat. No. 4,694,589.

In the embodiment shown in FIGS. 3A and 3B and FIG. 4, pillows 20 and 22 extend downwardly below the lower surface of cushioning layer 18 to provide extra cushioning at the ball of the foot area of forefoot portion 12 and at heel portion 14. In equally preferred embodiments, the arrangement of the material can result in the pillows protruding upward from the surface of cushioning layer 18. Preferably, cushioning layer 18 has a constant thickness throughout. For example, cushioning layer 18 can have a thickness of about 2 mm and the pillow 20 or 22 preferably having a thickness of about 3 mm. Thus, the combined thickness of cushioning layer and any pillow 20 or 22 would preferably have a thickness of about 5 mm.

As depicted in FIG. 5 top cover layer 24 can be secured to the upper surface of cushioning layer 18, although such a top cover layer 24 is not required. In such case, top cover layer 24 can be made from any suitable material including, but not limited to, fabrics, leather, leatherboard, expanded vinyl foam, flocked vinyl film, coagulated polyurethane, latex foam on scrim, supported polyurethane foam, laminated polyurethane film or in-mold coatings such as polyurethanes, styrene-butadiene-rubber, acrylonitrile-butadiene, acrylonitrile terpolymers and copolymers, vinyls, or other acrylics, as integral top covers. Desirable characteristics of top cover layer 24 include good durability, stability and visual appearance. It is also desirable that top cover layer 24 have good flexibility, as indicated by a low modulus, in order to be easily moldable. The bonding surface of top cover layer 24 should provide an appropriate texture in order to achieve a suitable mechanical bond to the upper surface of cushioning layer 18. Preferably, the material of top cover layer 24 is a fabric, such as a brushed knit laminate top cloth (brushed knit fabric/urethane film/non-woven scrim cloth laminate) or a urethane knit laminate top cloth. Preferably, top cover layer 24 is made from a polyester fabric material, and preferably has a thickness of about 0.02 inch.

Preferably the insoles of the present invention comprise a top cover 24 comprising a self adhesive low friction film material 26. The film material is chosen to be compatible with the gel material that comprises the remainder of the insole, described above. In one embodiment, the film material comprises a polyurethane when the gel material in the insole comprises polyurethane. In another embodiment, the film material comprises a styrenic block copolymer, such as the Kraton block copolymer of styrene/ethylene-co-butylene/styrene (SEBS) or styrene/butadiene/styrene (SBS) described above for the cushioning layer 18 when the gel material in the insole comprises styrenic block copolymers. As explained above, these copolymers comprise mineral oil incorporated into the matrix as a plasticizer, typically in high content of the gels, such as greater than 50%, and in some embodiments greater than 70% by weight and can be difficult to mechanically attach woven top cloth to the upper surface. It has been found that a gel film material comprising a styrenic block copolymer such as SEBS with mineral oil and polypropylene produces a suitable film material that can be added to an injection mold before the mold is loaded with the gel material to form the cushioning layer 18, thereby providing the low friction gel film top cover for the gel insoles of the invention. In certain embodiments, the gel film top cover can cover the entire top surface of the gel insole or can comprise only portions of the top surface. Thus, for example, as depicted in FIGS. 5-8, the gel film top cover can be used in addition to the other top surface material described above, whereby part of the top surface of the insole is a woven fabric or other material and part of the top surface is a gel film top cover. In certain embodiments, the gel film top cover will comprise only certain higher pressure points such as those areas of the insole 10 that will come in contact with the toes, ball of foot, and/or heel. Because the gel material of certain embodiments of insole 10 and the gel film top covers are substantially translucent, the arrangement of partial gel film top cover portions can be made to provide a decorative pattern as well.

As depicted in FIG. 6, in a further embodiment of the invention, cushioning layer 18 comprises a first elastomeric gel material 40 having a first hardness and within a recess in the bottom surface of the cushioning layer a second elastomeric gel material 42 having a second hardness different from the hardness of the first elastomeric gel material, the second elastomeric gel material located substantially in the mid-foot portion, preferably to be positioned below the arch of the foot. In a preferred embodiment, the first elastomeric gel material has a greater hardness than the second elastomeric gel material. For example the first elastomeric material may have a Shore OO hardness of between about 50 to about 65, preferably between about 55 to about 65, most preferably about 55. The second elastomeric gel material may have a Shore OO hardness of between about 30 to about 45, preferably between about 40 to about 45, most preferably about 45.

It will be appreciated that insole 10 is a full length insole extending along the entire foot. Typically, insole 10 would be sized corresponding to shoe sizes and would be provided in sized pairs. Alternatively, insole 10 may be trimmed to the requirements of the user. In this regard, arcuate pattern trim lines (not shown) may be formed on the lower surface of forefoot portion 12 of insole 10, which are representative of various sizes of the human foot. The pattern trim lines may be imprinted by conventional printing techniques, silkscreening and the like. As an alternative, the pattern trim lines may be formed as shallow grooves, or be perforated, so that a smaller size insole may be separated by tearing along the appropriate trim lines, which tearing operation is facilitated by the inclusion of perforations. Thus, forefoot portion 12 can be trimmed so that forefoot portion 12 fits within the toe portion of open style footwear.

Alternatively, a pattern trim line can be provided on the lower surface of cushioning layer 18 to cut around the thong of some types of open style footwear, if necessary.

In order to secure insole 10 to footwear, an area of adhesive 26, for example, by a double sided adhesive tape, is formed along the length of the lower surface of cushioning layer 18, and is covered by a release sheet 28. In this manner, a user merely removes release sheet 28 and adheres insole 10 to the footwear. Adhesive 26 can be a permanent adhesive or a release adhesive that permits removal and reapplying or repositioning of insole 10 in the footwear.

Alternatively, lower surface of cushioning layer 18 can be provided as a high friction surface to maintain insole 10 in position in the footwear. For example, synthetic rubber adhesive coating (not shown) can be added to lower surface 18a of cushioning layer 18 for this purpose.

Accordingly, with insole 10, cushioning pillows 20 and 22 are provided at the ball of the foot area of forefoot portion 12 and at heel portion 14 where most of the impact and forces occur during a gait. Further, such insole 10 fits within footwear, and will remain in position in such open style footwear during wearing by the user. Moreover, because of the upward curvature of the peripheral edges, the wearer experiences a more secure fit between the foot and insole, thereby enhancing comfort to the wearer.

Insole 10 can be also be secured to the footwear by using the tack properties of the gel. In this regard, it is preferred that the tack of the gel is enhanced by incorporating a tackifier into the gel composition to increase the friction/tack of the gel surface. Suitable tackifiers include a petroleum hydrocarbon resin sold under the designation I-Mark V by Idemitsu Kosan Co., Ltd. of Tokyo, Japan; the rosin sold under the trademark ASYLVALITE® under designation RE 80 for SEBS gels; and phenolsulfonic acid ester sold under the trademark AMESAMOLL® for a polyurethane (PU) gel. The desired tack is preferably between 120 and 250 grams, as determined by a probe tack tester sold under the trademark APOLYKEN®, at one second contact time.

Although the present invention uses the term insole, it will be appreciated that the use of other equivalent or similar terms such as innersole or insert are considered to be synonymous and interchangeable, and thereby covered by the present claimed invention.

Having described specific preferred embodiments of the invention with reference to the accompanying drawings, it will be appreciated that the present invention is not limited to those precise embodiments and that various changes and modifications can be effected therein by one of ordinary skill in the art without departing from the scope or spirit of the invention as defined by the appended claims.

Claims

1.-45. (canceled)

46. An insole for insertion into footwear, said insole comprising a forefoot portion, a midfoot portion and a heel portion; the midfoot portion connecting together the forefoot portion and the heel portion; said insole comprising a cushioning layer of a viscoelastic gel material which provides a cushioning function; wherein the cushioning layer is formed as a one-piece structure; wherein the midfoot portion and the heel portion comprise a peripheral edge that curves upwards; and wherein at least one of said forefoot portion and said heel portion contains a substantially dome shaped pillow protruding from said cushioning layer thereat wherein said substantially dome shaped pillow(s) comprise a plurality of spaced apart spring walls formed from said viscoelastic gel, said spring walls extending from a lower surface of said cushioning layer wherein said spring walls each have a height which is greatest at a center of said pillow and which tapers in height toward edges of said pillow.

47. An insole according to claim 46, wherein said cushioning layer and said substantially dome shaped pillow(s) are formed from the same viscoelastic gel material as a unitary, one-piece structure.

48. An insole according to claim 46, wherein said insole contains an arrangement for maintaining said insole in position in said footwear during use.

49. An insole according to claim 48, wherein said arrangement comprises providing a high friction material on a surface of the insole that contacts said footwear.

50. An insole according to claim 49, wherein said high friction material comprises an adhesive applied to at least a portion of a surface of the insole that contacts the footwear.

51. An insole according to claim 50, wherein said adhesive is a release adhesive that permits removal of the insole from the footwear and repositioning the insole in the footwear.

52. An insole according to claim 49, wherein said high friction material comprises tackifier material added to said viscoelastic gel material.

53. An insole according to claim 46, wherein each of said spring walls is formed in a generally sinusoidal wave shape.

54. An insole according to claim 46, wherein said cushioning layer has a substantially uniform thickness of about 2 mm

55. An insole according to claim 46, wherein said substantially dome shaped pillow(s) have a height less than about 3 mm.

56. An insole according to claim 46, further comprising a top cover secured to an upper surface of said cushioning layer.

57. An insole according to claim 56, wherein the top cover comprises a low friction film material.

58. An insole according to claim 57, wherein the low friction film material comprises a styrenic block copolymer.

59. The insole according to claim 58, wherein the low friction film material comprises a copolymer chosen from the group consisting of styrene/ethylene-co-butylene/styrene (SEBS), styrene/butadiene/styrene (SBS) and mixtures of styrene/ethylene-co-butylene/styrene (SEBS), styrene/butadiene/styrene (SBS).

60. An insole according to claim 57, wherein the low friction film material consists essentially of SEBS, mineral oil and polypropylene.

61. An insole comprising a forefoot portion, a mid-foot portion, and a heel portion, said forefoot portion, mid-foot portion and heel portion forming a cushioning layer comprising a resilient material having a first hardness and which provides a cushioning function, and a cushioning insert comprised within a recess in said cushioning layer and extending down from said cushioning layer; said cushioning insert comprising a resilient material having a second hardness that is less than the hardness of said cushioning layer.

62. An insole for insertion into footwear comprising a forefoot portion, a mid-foot portion and a heel portion forming a cushioning layer having upper and lower surfaces; which cushioning layer comprises a first elastomeric gel material having a first hardness and a second elastomeric gel material having a second hardness less than the hardness of the first elastomeric gel material, said second elastomeric gel material disposed within a recess in the bottom surface of the cushioning layer, the recess located substantially in the mid-foot portion positioned below the arch of the foot.

63. An insole according to claim 57, wherein the insole comprises said low friction film material on at least one of said forefoot portion, said midfoot portion and said heel portion.

64. The insole according to claim 46 wherein said gel material curves upward at the peripheral edge.