Polyurethane injected boot assembly and associated manufacturing method

A footwear assembly having an upper that comprises a neoprene sock with a foot portion integrally connected to a leg portion. The foot portion has heel, vamp and under-foot portions. The leg portion has front shin, side wall, and rear calf-side portions. The upper has a unitary, outer, injection molded layer molded directly onto the foot and shin portions of the neoprene sock, while the sidewall and rear calf-side portions remain substantially uncovered by the injection molded layer. The injection molded layer encases the foot portion of the neoprene sock. The injection molded layer on the shin portion defines a shin guard portion having a necked down area integrally connected to the injection molded layer at the vamp portion, wherein the shin guard extends upwardly from the necked-down portion in an outwardly diverging shape away from the vamp.

TECHNICAL FIELD

Embodiments of the present invention are directed to waterproof footwear, such as neoprene-based boots, and associated manufacturing methods.

BACKGROUND

Waterproof footwear, such as boots, are used in outdoor recreational activities as well as in a number of industrial and professional uses. For example, waterproof boots are often used in hunting and fishing to ensure that the sportsman's feet remain dry during the recreational activity. Additionally, waterproof boots are used in the animal husbandry and farming environments, as well as many other professional environments.

One type of waterproof boots includes over-the-calf boots made entirely of rubber. Other conventional waterproof boots include an outer rubber waterproof layer over an inner layer of supporting material. The use of rubber as the waterproof material can provide a number of functional benefits, because rubber of sufficient thickness is strong, resilient, puncture resistant, and fairly durable. Such rubber boots, however, are typically inflexible, heavy, and do not fit the wearer's foot and/or leg very well.

Other waterproof boots have been developed that include a neoprene inner layer fully covered by an outer layer of rubber vulcanized onto the neoprene. This neoprene and vulcanized rubber construction provides a light weight boot that fits better and is more comfortable than the all-rubber boots. The manufacturing process of laying up the rubber and vulcanizing it onto the outside of the neoprene sock is a fairly laborious manufacturing process, which can increase the boot's manufacturing cost. The heat applied to the boot assembly during the vulcanization process can also have a negative effect on the inner neoprene sock. For example, the neoprene may be susceptible to taking a set and losing elasticity during the vulcanization process. Accordingly, there is a need for an improved light weight, waterproof boot and associated method of manufacture.

SUMMARY

Boot assemblies and associated manufacturing methods in accordance with the present disclosure provide waterproof boots that overcome drawbacks of the prior art and that provide other benefits. In at least one embodiment, a boot assembly includes a neoprene sock having inner and outer surfaces, and an outer layer of injection molded material on selected portions of the neoprene sock's outer surface including on the heel area, the ankle area, the vamp area, the under-foot area, and the shin area. Other portions of the neoprene sock's outer surface remain uncovered by the injection molded material.

An aspect of the present disclosure provides a footwear assembly having an outsole and an upper connected to the outsole. The upper comprises a neoprene sock having foot and leg portions, and the foot portion is integrally connected to the leg portion. The foot portion has a heel portion, a vamp portion and an under-foot portion. The leg portion has a front shin portion, side wall portions, and a rear calf-side portion. The upper has a unitary outer injection molded layer molded directly onto the foot portion and the shin portion of the neoprene sock, while the sidewall portions and rear calf-side portion remain exposed and substantially uncovered by the injection molded layer. The injection molded layer encases the foot portion of the neoprene sock. The injection molded layer on the shin portion defines a shin guard portion having a necked down area integrally connected to the injection molded layer at the vamp portion, wherein the shin guard extends upwardly from the necked-down portion in an outwardly diverging shape away from the vamp.

Another aspect of the disclosure provides a lightweight, waterproof footwear assembly combineable with an outsole. The footwear assembly has an upper connectable to the outsole, and the upper comprises a neoprene sock having a foot portion integrally connected to a leg portion. The foot portion has an ankle portion, a heel portion, a vamp portion, and an under-foot portion. The leg portion has a front shin portion, side wall portions and a rear calf-side portion. The upper comprises a unitary outer injection molded layer molded directly onto the foot portion and a first portion of the leg portion of the neoprene sock while second portions of the leg portion remain exposed and substantially uncovered by the injection molded layer. The injection molded layer encases the foot portion of the neoprene sock. The injection molded layer at the foot portion has a plurality of integral convertible channels of reduced thickness around the ankle portion in a configuration conforming to a top edge of a boot. The convertible channels define cut lines along which the upper can be cut during manufacture to define a top edge of a boot of a selected height.

Another aspect of the disclosure provides a method of making a waterproof footwear assembly. The method comprises enclosing a neoprene sock in an injection molding assembly, wherein the neoprene sock comprises an interior area and an exterior surface facing away from the interior area. The neoprene sock has a foot portion integrally connected to a leg portion. The foot portion has a heel portion, a vamp portion and an under-foot portion. The leg portion has a front shin portion, side wall portions and a rear calf-side portion. The method includes injecting a flowable, injection moldable material into the molding assembly adjacent to the foot portion of the neoprene sock. The method includes forming an injection molded layer of the injection moldable material directly on a portion of the exterior surface of the neoprene sock, wherein the injection molded layer covers the foot portion and the front shin portion, and wherein the sidewall portions and the rear calf-side portion remain exposed and substantially uncovered by the injection molded layer. The method includes molding the injection moldable material onto a portion of an outsole connecting the outsole to the neoprene sock, wherein an under-foot portion of the injection moldable material interconnects the neoprene sock to the outsole.

DETAILED DESCRIPTION

The present disclosure describes waterproof boot assemblies and methods of manufacturing the boot assemblies in accordance with certain embodiments of the present invention. Several specific details of the invention are set forth in the following description and the Figures to provide a thorough understanding of certain embodiments of the invention. One skilled in the art, however, will understand that the present invention may have additional embodiments, and that other embodiments of the invention may be practiced without several of the specific features described below.

As seen inFIGS. 1-3, a waterproof boot assembly10in accordance with an embodiment of the present disclosure includes an upper12integrally connected to an outsole14. The upper12is an over-the-calf upper that includes a leg portion16with an ankle portion17integrally connected to a foot portion18, which has a heel portion20and a vamp portion22. The upper12includes a full-foot neoprene sock24shaped and sized to receive the wearer's foot and to extend upwardly over the ankle and cover the wearer's shin and calf. The neoprene sock24has an inner layer26, an outer layer28, and a neoprene layer30sandwiched between the inner layer26and the outer layer28. The inner layer26defines the interior area of the entire boot from the foot portion18, through the ankle portion17and to the top of the leg portion16. The inner layer26can be a fabric material, such as nylon, cotton, canvas, fleece, insulation, wool, mesh, or other selected materials.

The neoprene layer30carries the inner layer26and the outer layer28. The neoprene layer of the illustrated embodiment has a thickness of approximately 3.5 mm. Other embodiments can include a neoprene layer with a thickness of approximately 7.0 mm. Yet other embodiments can include a neoprene layer with other thicknesses or a combination of thicknesses. The neoprene layer30of the illustrated embodiment is formed from two pieces of neoprene material. One piece forms the floor region upon which a wearer's foot is supported, and the second piece of neoprene is shaped to cover the vamp, heel, ankle and lower leg regions. The two pieces of neoprene can be connected to each other via stitching or other conventional techniques for joining pieces of neoprene together. In one embodiment, the floor region of the neoprene sock24is formed by a puncture resistance insole board, such as a LENZI® insole board or the like, to which the rest of the neoprene layer30is attached and/or stitched. In the illustrated embodiment, the second piece of the neoprene is stitched to itself to close the heel, ankle, and leg portions of the neoprene sock24. In this arrangement, the neoprene sock24has a stitched seam32that extends vertically along the back side of upper (i.e., along the calf-side34of the leg portion16) between the heel portion20and the top of the leg portion16. Other embodiments can have a seam in other locations, such as along the top of the vamp portion22and along the front or shin-side36of the leg portion16. In yet other embodiments, other configurations of the neoprene can be used to provide a seam in other locations.

The outer layer28can also be a fabric material securely affixed to the outer surface of the neoprene layer30. The outer layer28can cover the entire neoprene layer. In other embodiments, the outer layer28can cover only selected portions of the neoprene layer, such as those portions of the neoprene sock24exposed and visible from exterior of the boot assembly10, as discussed in greater detail below. The outer layer28can be a durable fabric material, such as Spandura®, nylon, cotton, canvas, fleece, wool, mesh, or other selected materials. The outer layer can also be one or more selected colors, and/or it can include camouflage, designs, images, indicia, or other visual features.

The upper12includes an outer polyurethane (PU) layer40injection-molded directly onto portions of the neoprene sock24, while other portions of the neoprene sock remain uncovered (i.e., PU-free). The PU material can be injection molded directly onto the outer surface of the neoprene layer30, or onto the outer surface of the outer layer28, or both. The PU material is lightweight, durable, and has better insulative properties than vulcanized rubber. The injection-molded PU layer40is also permanently connected to the outsole14so as to fixedly connect the outsole14to the upper12. In the illustrated embodiment, the injection-molded PU layer40fully covers the neoprene sock24in the vamp portion22, the heel portion,18and the ankle portion17. Other portions of the neoprene sock24, such as the calf-side34and sidewalls of the leg portion16, remain uncovered and exposed.

As shown inFIGS. 4 and 5, the injection-molded PU material is molded around the entire foot portion of the neoprene sock24, such that the PU material extends under the bottom of the neoprene sock between the sock's bottom panel25and the outsole14. This “under-foot” layer of PU material between the neoprene sock24and the outsole14is sufficiently thick to define a cushioning and/or shock attenuation layer under the wearer's foot, so as to effectively act as an integrated midsole portion29to which the outsole14is attached. The integrated PU midsole portion29can have varying thicknesses under the foot to achieve selected performance or comfort objectives. In one embodiment, the integrated PU midsole portion29can be thicker in the heel area to absorb or otherwise reduce impact loads at heel strike of the wearer's gait cycle. The integrated PU midsole portion29can be configured in the arch area to essentially encapsulate a shank positioned under the neoprene sock's bottom panel25in the arch area. In another embodiment, the shank can be positioned between the outsole14and the midsole portion29. In yet another embodiment can include the shank fully encapsulated within the midsole portion29. Accordingly, the injection molded PU material on the neoprene sock24can also include the integral midsole portion underfoot, which is formed in the same single injection molding process, discussed in greater detail below.

The injection molded PU material can also be configured with a selected thickness over the vamp portion22to provide impact protection to the instep and/or metatarsal regions of the wearer's foot. In one embodiment, each of the neoprene layer and the PU material have cushioning and shock attenuation characteristics. The combination of the neoprene layer and the PU material layer at the vamp portion22can be configured with a selected thickness to form an integrated metatarsal guard construction that provides sufficient shock absorption and impact abatement to meet or exceed the ANSI and/or ASTM metatarsal guard requirements for footwear. Accordingly, the resuling footwear assembly10can be a certified metatarsal guard footwear assembly. In one embodiment, such metatarsal guard protection can be provided using a neoprene sock with a thickness of approximately 3.5 mm and the PU material having a thickness of approximately 4 mm-8 mm at least at the vamp portion. In one embodiment, the PU material has a thickness of approximately 6 mm at the vamp portion and/or the shin guard portion. Other embodiments can use other thicknesses of the neoprene sock and/or the PU material to provide the selected metatarsal guard construction.

In another embodiment, a metatarsal guard insert can be provided over the vamp portion22of the neoprene sock prior to injection molding the PU material onto the neoprene sock24. When the PU material is injection molded onto the neoprene sock24, the metatarsal guard insert is fully covered and/or encapsulated within the PU material. In this construction, the metatarsal guard insert may or may not be visible from the exterior of the footwear assembly10.

A similar construction may be provided with a toe guard insert covered by the PU material. A toe guard insert, such as a certified non-metallic toe cap, can be positioned over the toe area of the neoprene sock24prior to injecting the PU material onto the neoprene sock24. When the PU material is injected onto the neoprene sock24, the toe Insert Is fully covered and/or encapsulated by the PU material layer. The result is a lightweight, highly insulative, boot or shoe having the certified toe guard protection.

In yet another embodiment, a puncture resistant layer can be provided along the bottom of the neoprene sock (i.e., under foot). The puncture resistant layer can be a metallic or nonmetallic material that provides sufficient puncture resistance in accordance with the ANSI or ASTM standards or other similar performance standard for footwear. At least one embodiment includes a puncture resistant material manufactured by LENZI®. The puncture resistant material can be part of an insole board. The puncture resistant layer can be positioned adjacent to the bottom of the neoprene sock24, and then the PU material is injection molded onto the neoprene sock, so the puncture resistant material is fully covered and/or encapsulated by the PU material. The result is a lightweight, durable, certifiable puncture-resistant footwear assembly that meets or exceeds manufacturing, performance and safety requirements and regulations for footwear.

The PU layer40also forms a shin guard42on the shin side36of the leg portion16. The shin guard42has a narrow or necked-down area44integrally connected to the PU material on the front of the ankle portion17above the vamp portion22. The shin guard42extends upwardly from the necked-down area44in an outwardly diverging shape to the top edge of the leg portion16. The integral shin guard42terminates along side edge portions46so that the front of the upper12protects the wearer's shin, while the sides of upper12are PU-free with the neoprene sock24uncovered and exposed. The necked-down portion44at the bottom of the shin guard42helps maintain flexibility and comfort of the boot's leg portion16, while providing a path through which the PU material can flow from the vamp and ankle portions to the shin guard area during the injection molding process, discussed in greater detail below. In one embodiment, the PU material is injected into the mold (discussed below) near the toe portion of the neoprene sock24so the PU material substantially simultaneously flows around the foot portion of the neoprene sock and along the shin portion. In other embodiments, the PU material can be initially injected into the mold adjacent to a different portion of the neoprene sock during the molding process.

The embodiment(s) described herein and shown in the figures include the layer of PU material injection molded onto the selected portions of the neoprene sock. Other embodiments can utilize other suitable flowable, injection moldable materials, such as thermoplastic polyurethane (TPU), Styrene Ethylbutylene Styrene (SEBS), or other suitable flowable injection-moldable material that can be injection molded directly onto selected portions of the neoprene sock24in a single molding process.

The injection molded layer40can be any of a range of colors or combination of colors. The PU layer40in other embodiments can include a selected camouflage pattern. In yet other embodiments, the injection-molded layer40other may be transparent or semi-transparent, so that portions of the neoprene sock24under the injection molded layer can be visible. As an example, one embodiment the neoprene sock24includes a camouflage pattern over most of its outer surface, and the injection molded layer is made of a clear TPU or clear SEBS material so virtually all the camouflage pattern of the neoprene sock24is visible to the user, including through the injection molded layer.

In the illustrated embodiment, the leg portion16of the upper12includes a gusset48on the calf-side34of the leg portion. The rest of the neoprene sock24above the ankle portion17on the calf-side34is exposed and not covered by the injection-molded PU material. The gusset48can be formed of a neoprene material, rubber, or other suitable flexible material to accommodate the stresses and folding forces applied to the gusset. The edges of the gusset48can be stitched directly to the top area of the leg portion, thereby creating a one or more seams between the gusset and the upper's leg portion. The seam(s)32along the calf-side34of the leg portion16can be sealed by a strip of vulcanized rubber, waterproof tape or other suitable waterproof covering. In another embodiment, a flowable sealant, such as a flowable rubber, can be applied to the seam and allowed to dry or cure to provide a waterproof covering over the seam(s). In another embodiment, a strip of PU material can be injection molded directly onto to neoprene sock24during the single-shot injection-molding process so as to cover and waterproof the entire seam32. This seam-covering strip of PU material is integrally connected to the injection-molded PU material of the ankle portion17above the heel portion20. While the illustrated embodiment includes the gusset48, the upper12in other embodiments does not include a gusset48. In such a configuration, the seam-covering strip of PU material can extend all the way to the top edge of the upper. In other embodiments, the leg portion16can include a zipper or other expandable/closeable entry system at the top of the leg portion that can help facilitate taking the boot assembly on and off of the wearer's foot/leg. Such entry system can be gusseted systems or gusset-free systems.

As seen inFIGS. 1-4, the injection molded PU layer40has a plurality of channels50formed into the PU material. The channels50are provided in the vamp portion22, the ankle portion17, the heel portion20, and the shin guard42. These channels50define areas of the PU material having reduced thicknesses, which decreases the overall weight of the boot assembly. In one embodiment, the PU layer at the channels has a thickness of approximately 2 mm, and the thickness of approximately 4 mm away from the channels50. Other embodiments can have injection-molded PU material with different thicknesses. The channels50can also define flex grooves51in portions of the upper12that allow the upper12to bend or flex during use. For example, the flex grooves51in the vamp portion22and in the front of the ankle portion17allow the upper12to flex easily to accommodate for the movement of the wearer's lower leg, ankle, and foot while walking or running.

The boot assembly10of the illustrated embodiment is a full, over-the-calf boot having a height of, as an example, sixteen or eighteen inches from the bottom of the outsole14to the top edge53of the leg portion16. The boot assembly10is configured as a convertible boot assembly that can be finished during the manufacturing process as either the full over-the-calf boot or as a shorter boot/shoe. The injection-molded PU layer40is formed over the neoprene sock24with a plurality of the channels50being convertible channels52extending around the upper12. The convertible channels52define areas along which the upper12can be cut to shorten the upper and then finished during the manufacturing process to form shorter footwear. For example,FIGS. 3 and 6show the convertible channels52that include a lower convertible channel54formed in the PU layer40around the upper12just below the ankle portion17. After the PU layer40is injection molded onto the neoprene sock24, the upper12can be cut along the lower convertible channel54and the top edge of the upper is finished, such as with a binding stitch, to form a 4.5-inch slip-on waterproof shoe (FIG. 6), referred to as a “camp moc.”

FIGS. 3 and 7show the convertible channels52that include a 7-inch convertible channel56formed in the PU layer40around the upper12just below the shin guard42(FIG. 3) and along the top edge of the rest of the injection molded PU layer24. The upper12can be cut along the 7-inch convertible channel56and the top edge of the upper is finished with a binding stitch or the like to form a 7-inch slip-on waterproof boot (FIG. 7).FIGS. 3 and 8show the convertible channels52that include a 12-inch convertible channel58formed in the PU layer40in the shin guard42between the necked portion44and the top edge53of the leg portion16. The upper12can be cut along the 12-inch convertible channel58and the top edge of the remaining upper12is finished with a binding stitch or the like to form a 12-inch waterproof boot (FIG. 8). The 12-inch waterproof boot of the illustrated embodiment includes portions of the neoprene sock24above the PU layer40that remain exposed and uncovered by the PU material.

While the illustrated embodiments are shown with convertible channels52that include at least the lower convertible channel 5.4-inch, the 7-inch convertible channel56, and the 12-inch convertible channel58, the boot assembly10can include a greater or fewer number of convertible channels52in different positions and/or orientations along which the upper12can be cut and finished to form footwear of different heights. This configuration allows the same mold to be used in the manufacturing of a plurality of boot assemblies having different heights, which can increase efficiency and reduce the manufacturing cost.

The boot assembly10of the illustrated embodiment is manufactured by forming the entire neoprene sock24having the selected inner layer26and the outer layer28. In the illustrated embodiment, the outer layer28is a layer of Spandera™ that includes a camouflage pattern, but other outer layers can be used. The neoprene sock24is securely positioned over a rigid last60of a mold assembly62, shown inFIG. 9. The last60is connected to and extends from a vertical support64in a cantilevered arrangement. The mold assembly62includes a pair of side die plates66pivotally attached to the support64. The side die plates66are movable from an open position (FIG. 9) and a closed position (FIG. 10). In the open position, the side die plates66are spaced away from the last60so as to expose and provide access to the last60. In the closed position, shown inFIG. 10, the side die plates66enclose the last60and closely conform to the neoprene sock on the last.

The mold assembly62can be configured for use with neoprene socks having different thicknesses, such as for different models of the boot assembly. In one embodiment, the last60is sized and configured to receive the thickest neoprene sock in the different models of the upper. When a thinner neoprene sock is needed for a different model, a spacer can be placed on the last to accommodate for the thickness variations of the neoprene material. As an example, the mold assembly62of one embodiment is constructed for use with a neoprene sock24having a thickness of about 7 mm. The last60for the mold assembly62is for a predetermined foot size, such as a size US9, using the 7 mm sock. The same mold assembly62is also used for a boot having a neoprene sock with a 3.5 mm thickness, by inserting a 3.5 mm thick spacer (such as a spacer sock) on the last60before the 3.5 mm thick neoprene sock24is placed on the last. Accordingly, the 3.5 mm neoprene sock is slipped onto the last60over the spacer sock. In one embodiment, the spacer sock is a 3.5 mm thick neoprene spacer sock.

In this embodiment using the 3.5 mm thick neoprene sock over the last60and the spacer sock, the resulting boot assembly10will have a larger interior area than the boot with the 7 mm thick neoprene sock made using the same mold assembly62. The mold assembly62is specifically designed, however, so that the boot with the 3.5 mm thick neoprene sock will be a larger size (e.g., approximately size US10) than the boot with the 3.5 mm thick neoprene sock (e.g., approximately size US9). Accordingly, the exact same mold assembly62can be used to make two different versions of a boot with different neoprene thicknesses and with different boot sizes. This decreases manufacturing costs by using the same mold assembly62during the injection molding of a plurality of models or versions of the boot assemblies without having to change or revise the mold, other than by using spacer socks or other spacer devices. Other embodiments include a plurality of molds with lasts that are specifically sized to accommodate neoprene socks having different thicknesses with out needing to use a spacer or the like.

The mold assembly62also has an outsole die plate68configured to securely retain and position the outsole14(FIG. 3) immediately adjacent to the bottom of the neoprene sock24(FIG. 3). The outsole die plate68of the illustrated embodiment is pivotally attached to the end portion of one of the side die plates66. In one embodiment, the outsole die plate68can be removeable from the side die plate66and replaced with a different outsole die plate. This allows the mold assembly62to be used with different outsoles or different outsole patterns or materials. For example, a run of boots with a first construction or outsole pattern can be made using the mold assembly, and then outsole die plate68can be quickly and easily removed and replaced with a different outsole die plate. The mold assembly62with the new outsole die plate68can then be used to make another run of boots having different outsoles from those of the first run. In other embodiments, the outsole die plate68can be changed to modify the configuration (i.e., thickness, arrangement, distribution, etc.) of the integrated PU midsole portion29without having to use a completely different mold. The removeable outsole die plates68can also be configured to accommodated outsoles made of different materials. One outsole die plate68can be used with rubber outsoles, and another outsole die plate can be used for an injection molded outsole or an other type or style of outsole.

The outsole die plate68releasably locks onto the bottom of the other side die plate66when in the closed position to fully enclose the outsole14and the neoprene sock24within the mold assembly62. The mold assembly62securely retains the neoprene sock24in a position so that the PU material can be injected into the mold so as flow over and cover only the selected portions of the outsole and neoprene sock, while the remaining portions of these components remain free of the injection molded PU materials. The mold assembly62is also configured to precisely hold the outsole14apart from the bottom panel of the neoprene sock24such that PU material will flow and fill the entire space between the sock's bottom panel and the outsole14to securely fix the outsole14to the upper12. In at least one embodiment, the outsole14may include an adhesive material that adheres the outsole14directly to the bottom of the neoprene sock24as the PU material is injected into the mold and over the selected portions of the outsole14and the neoprene sock24.

The side die plates66have contoured interior surfaces70that correspond in negative relief to the shape and arrangement of the boot assembly10. For example, the contoured interior surfaces70have vamp, heel, ankle, and shin guard portions spaced a selected distance from the outer surface of the neoprene sock24in the corresponding vamp, heel, ankle and shin guard areas. Accordingly, during the injection molding process, the flowable PU material is injected into the mold assembly62, when in the fully closed position, and uniformly flows over the selected outer surfaces of the neoprene sock24into only the spaces between the die plates66and the neoprene sock24to form the PU layer24.

The contoured interior surfaces70of the side die plates66also include a plurality of ridges72in selected locations that define the flex grooves51and the convertible channels52in the PU layer40during the injection molding process. The contoured interior surfaces70also include one or more dam portions74that firmly and sealably engage the neoprene sock along the edges of the area to which the PU is allowed to flow. The dam portions74prevent the flowing PU material from bleeding onto the outer surface of the neoprene sock24that is to remain exposed and PU-free. The dam portions74must be carefully sized and controlled so as to press against the neoprene sock24firmly enough to prevent leakage of the PU material but not enough to crush and damage the neoprene material. In at least one embodiment, the dam portions74are carefully shaped and sized as a function of the characteristics of the PU material (i.e., the viscosity, etc.) and the characteristics of the neoprene material (i.e., its crush resistance) to ensure proper control of the flowing PU material without damaging the neoprene sock.

The dam portions74of the side die plates66also define the shape of the shin guard42and the necked down portion44between the bottom of the shin guard and the ankle portion of the upper12. The side die plates66are configured at the shin guard area and the necked down area so that the PU material injected into the bottom of the mold assembly62, when in the closed position, will smoothly and uniformly flow over the foot and ankle areas of the neoprene sock42, and through the necked down portion and fully fill the space in the mold that defines the shin guard area. This shin guard area is shaped, sized, and configured in the diverging arrangement so that the injected PU material will consistently fill the entire space to form the entire shin guard42to the top edge of the neoprene sock without leaving any air holes, bubbles or other areas of incomplete dispersal of the PU material. Accordingly, the mold assembly62is configured for uniform repeatability of forming the boot assembly10.

In operation, the empty mold assembly62is moved to the open position, and the neoprene sock24is securely positioned onto the last60. An outsole14is positioned on the outsole die plate68, and the mold assembly is moved to the closed position with the outsole die plate68and the side die plates66fully enclosing the neoprene sock. In this arrangement, the outsole14is also held in firm engagement with the bottom of the neoprene sock to allow a layer of adhesive to permanently adhere the two components together.

The mold assembly62is then locked in the closed position, and a selected volume of heated, flowable PU material is injected into the mold assembly at a selected rate so as to flow over and bond to only the desired areas of the neoprene sock24to form the PU layer. The PU material also flows around selected portions of the outsole14to help hold the outsole in place and to provide a smooth transition between the outsole14and the upper12. The dam portions74on the die plates completely block the PU material from bleeding onto portion of the neoprene sock24that are to remain uncovered and exposed. The injected PU material is allowed to cure and cool, and then the mold assembly62is unlocked and moved to the open position to expose the boot assembly10on the last60. The boot assembly10can then be removed from the last60, and another neoprene sock24positioned on the last60in preparation for forming another boot assembly10. This configuration allows all of the PU material to be applied to the neoprene sock in a single injection molding operation, which can greatly reduces manufacturing time and associated costs. Other embodiments, however, can include a manufacturing process wherein PU material may be injection molded onto various portions of the neoprene sock in more than one step.

If the boot assembly10being manufactured is the full-height, over-the-calf boot, the top edge of the upper12is finished, such as by binding stitching the top edge, after the boot assembly is removed from the mold assembly62. A foot bed, insole, or other insert may be positioned into the interior area of the boot assembly after the boot assembly is removed from the mold assembly62. If the boot assembly10being manufactured is a shorter model, the upper12can be cut along the selected convertible channel52, such as the lower convertible channel54, the 7-inch convertible channel56, the 12-inch convertible channel58, or another convertible channel. After the upper12has been cut along the selected convertible channel52to the desired height, the top edge of the upper's remaining portion is finished to complete the shorter, waterproof footwear assembly, such as the 4.5-inch “camp muc” shoe, the 7-inch boot, or the 12-inch boot. The upper portion of the neoprene sock24and any of the associated PU layer cut from the upper is manufacturing waste that can be recycled or thrown away.

In another embodiment, the boot assembly10made on the mold assembly62can include inserts between the neoprene sock24and a portion of the injection molded layer. For example, a shank can be positioned under the bottom of the neoprene sock as discussed above. Another embodiment can include a protective toe cap (i.e., a safety toe) that fits over the toe of the neoprene sock and is essentially encapsulated in the layer of injection molded material. Other embodiments can include other protective features such as a metatarsal guard, a puncture proof layer under foot, a snake guard layer associated with some or all of the upper, and/or other protective features.

From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the invention. Additionally, aspects of the invention described in the context of particular embodiments or examples may be combined or eliminated in other embodiments. Although advantages associated with certain embodiments of the invention have been described in the context of those embodiments, other embodiments may also exhibit such advantages. Additionally, not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.