TOE BOX

Abstract

A toe box installed in a shoe tip of work footwear for protecting a toe includes a toe box body integrally formed by a shell body to cover the toe. The shell body connects a tip wall, a left side wall, a right side wall, and an upper wall with a smoothly curved surface. The tip wall, the left side wall, the right side wall, and the upper wall are made of a synthetic resin material. A front surface and a back surface of the upper wall are formed as a smooth surface, and the front surface of the upper wall is provided with a woven fabric formed of nylon resin fiber through an adhesive layer.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims priority to Japanese patent application No. 2016-169728, filed on Aug. 31, 2016, the disclosure of which is hereby incorporated by reference herein in its entirety.

This disclosure relates to a toe box for work footwear such as safety footwear.

BACKGROUND

Patent Literature 1 (PTL 1), JP 3,094,797 U teaches a thin-layered reinforcement structure in which a reinforcement layer is applied to a base layer body. The thin-layered reinforcement structure of PTL 1 includes the base layer body such as a toe cap for safety footwear made of fiber-reinforced thermosetting resin, and the base layer body is provided in the base layer body. The reinforcement layer is manufactured by impregnating a fiber woven fabric of thermoplastic resin into thermosetting resin. The reinforcement layer may be formed as a single layered structure or a multilayered structure in which a plurality of the reinforcement layers are provided inside the base layer body. The base layer body is manufactured by adding a fiber such as a glass fiber onto the thermosetting resin such as epoxy resin and phenol resin. For the fiber woven fabric of thermoplastic resin, a woven fabric having a melting point of 160 to 260 degrees and 900 to 4800 denier (for example, Nylon or PET fiber) is preferable.

The thin-layered reinforcement structure is to reinforce the strength of the toe cap by providing the reinforcement layer on the surface of the base layer body. The reinforcement layer is formed of the base layer body manufactured by the fiber-reinforced thermosetting resin, and is manufactured by impregnating the fiber woven fabric of thermoplastic resin into the thermosetting resin. That is, the fiber woven fabric of thermoplastic resin is impregnated with the thermosetting resin such as epoxy resin and phenol resin to form the base layer body so as to harden the thermosetting resin and to integrally provide the reinforcement layer in the base layer body.

SUMMARY

The above-described thin-layered reinforcement structure integrally provides the reinforcement layer in the resin constituting the base layer body. Thus, it is necessary to inject the resin constituting the base layer body after placing the reinforcement layer inside the mold. Further, the above thin-layered reinforcement structure is hardened in the manner of which the thermosetting resin constituting the base layer body is impregnated into the cloth of the woven fabric constituting the reinforcement layer. Accordingly, the surface of the hardened thermosetting resin has small irregularities. That is, the small irregularities such as stitch patterns are formed on the surface of the base layer body (i.e., the border between the reinforcement layer and the base layer body). However, it is preferable not to have such irregularities on the surface of the base layer body to suppress generation of a crack when receiving an impact.

To measure the performance of the toe box for safety footwear, an impact resistance test may be carried out. In the test, a striker is dropped freely on and collided with the toe box. For the impact resistance test, there are several standards such as Japanese Industrial Standards (JIS), H-division (100 J), S-division (70 J), and L-division (30 J). Additionally, there is a known standard called Canadian Standards Association (CSA; 120 J). Here, “J” denotes a unit for the falling energy (i.e., impact energy) of the striker. Here, the toe box may be made of steel or resin including glass fiber and the toe box made of glass fiber is required to satisfy CSA standards (120 J) in addition to the JIS S-division (70J).

In view of the above, an object of the present disclosure is to provide a resin toe box for safety footwear that has an impact resistance performance satisfying the CSA standards (120 J) without a significant change of the external shape and/or the weight of the conventional toe box which still satisfies the JIS standards, S-division.

To achieve the above object, an aspect of the present disclosure provides a toe box installed in a shoe tip of work footwear for protecting a toe. The toe box includes a toe box body integrally formed by a shell body to cover the toe. The shell body connects a tip wall, a left side wall, a right side wall, and an upper wall with a smoothly curved surface. The tip wall, the left side wall, the right side wall, and the upper wall are made of a synthetic resin material. A front surface and a back surface of the upper wall are formed as a smooth surface, and the front surface of the upper wall is provided with a woven fabric formed of nylon resin fiber through an adhesive layer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an external perspective view of a toe box according to an embodiment of the present disclosure. FIG. 2 is a plan view of the toe box according to the embodiment. FIG. 3 is a bottom view of the toe box according to the embodiment. FIG. 4A is an external photograph of a front surface of a toe box showing a result of an impact resistance test on a sample A. FIG. 4B is an external photograph of a back surface of the toe box showing the result of the impact resistance test on the sample A. FIG. 5A is an external photograph of a front surface of a toe box showing a result of an impact resistance test on a sample B. FIG. 5B is an external photograph of a back surface of the toe box showing the result of the impact resistance test on the sample B. FIG. 6A is an external photograph of a front surface of a toe box showing a result of an impact resistance test on a sample C. FIG. 6B is an external photograph of a back surface of the toe box showing the result of the impact resistance test on the sample C. FIG. 7A is an external photograph of a front surface of a toe box showing a result of an impact resistance test on a sample D. FIG. 7B is an external photograph of a back surface of the toe box showing the result of the impact resistance test on the sample D. FIG. 8 is an explanatory view for explaining a method of the test.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure is described with reference to the accompanying drawings. FIG. 1 is an external perspective view of a toe box 1 for work footwear such as safety footwear in accordance with an embodiment of this disclosure. FIG. 2 is a plan view of the toe box 1, and FIG. 3 is a bottom view of the toe box 1. Here, FIGS. 1-3 only show a toe box installed in a shoe for a left foot and the description for a toe box installed in a shoe for a right foot is omitted since the toe box in the left shoe is formed in a symmetrical shape and the technical effect is identical to that of the right shoe.

The toe box 1 includes a toe box body 2. The toe box body 2 is a shell body integrally formed by heat-pressure molding or heat-compression molding synthetic resin including a glass fiber. Here, the synthetic resin should be resin that has an excellent impact resistance and is easy to mold. For example, the synthetic resin may be polycarbonate, PC alloy (i.e., copolymer resin of polycarbonate and PBT resin, for example), ABS, or PET. More preferably, the synthetic resin may be a resin further having an excellent chemical resistance. For example, the synthetic resin may be polypropylene or nylon. The toe box body 2 is formed as a shell body constituting the shoe tip part of the footwear and is installed in the tip of an upper leather to protect the toes. The toe box body 2 includes a tip wall 3 constituting the shoe tip part, a left side wall 4 extending rearward from the shoe tip part, a right side wall 5, and an upper wall 6 covering above the shoe tip part. Each wall is connected with a smoothly curved surface such that the toe box body 2 is formed as the shell body having a bowl shaped part. The inside of a mold for molding the toe box body 2 does not have an irregularity on the surface such that the inside of the mold does not have a sharp corner or edge. The external surface of the toe box body 2, therefore, is formed as a smooth surface having no scratch or irregularities.

An edge portion having a predetermined width is extended from the tip wall 3, the left side wall 4, and the right side wall 5. The edge portion then forms a skirt 7 by bending and folding the lower end edge inward. The skirt 7 is provided to suppress deformation of the toe box 1 when the toe box 1 receives load or shock. Further, the skirt 7 prevents the toe box 1 from sinking to the shoe sole made of a plastic material such as rubber and urethane. Accordingly, the skirt 7 prevents the space for accommodating the toes from being narrowed and reduced so as to prevent the toes from being squeezed.

The toe box body 2 is configured such that the rear end of the side wall close to the foot little finger is extended rearward compared to the rear end edge 11 of the upper wall. Accordingly, the toe box body 2 is able to protect the little finger. Here, the extended side wall portion 8 does not include an upper wall such that the extended side wall portion 8 does not disturb the finger bending movement during walking and during bending knees.

On the upper surface of the upper wall 6 of the toe box body 2, a woven fabric (first woven fabric) is attached through an adhesive layer. Here, the woven fabric is made of nylon. It is suitable and preferable for the first woven fabric 9 to be a high density fabric such that the first woven fabric 9 is applicable to a vehicle air bag. For example, the first woven fabric 9 may be made of fibers formed of the nylon 66 or the nylon 6. The woven fabric is attached to the upper surface of the upper wall 6 of the toe box body 2 by an adhesive agent. The adhesive agent is a urethane-based adhesive as urethane-based adhesives have an excellent flexibility and excellent impact peeling resistance. Further, the back side of the upper wall of the toe box body 2 is also attached with a woven fabric (second woven fabric) 10. It is suitable and preferable for the second woven fabric 10 to be a high density fabric such that the second woven fabric 10 is applicable to a vehicle air bag. For example, the second woven fabric 10 may be made of fibers formed of the nylon 66 or the nylon 6. The second woven fabric 10 is formed in a substantially semicircular shape in accordance with a shape of the back surface of the upper wall 6. To be specific, the second woven fabric 10 is attached to the back side of the toe box body 2 such that the straight line of the second woven fabric 10 substantially matches the rear end edge 11 of the upper wall 6. Further, the center of the semicircular part substantially matches the center of the rear end edge 11 in the width direction.

The first woven fabric 9 and the second woven fabric 10 are bonded or adhered to the toe box body 2 with the adhesive agent. The adhesive agent should be made of a component that will not dissolve or damage the nylon-made first woven fabric 9 and the second woven fabric 10. Further, in this embodiment, neither a heating process nor a pressurizing process, which may change the composition of the woven fabrics, is executed to bond the woven fabrics to the toe box body 2. Therefore, the reinforcing action on the toe box body 2 can sufficiently be achieved without deteriorating or impairing the strength and the mechanical performance of the woven fabrics.

The first woven fabric 9 is formed in a substantially semicircular shape in accordance with a shape of the upper surface of the upper wall 6. To be specific, the first woven fabric 9 is attached to the toe box body 2 such that the straight line of the second woven fabric 10 substantially matches the rear end edge 11 of the upper wall 6 and the center of the semicircular part substantially matches the center of the rear end edge 11 in the width direction. On the upper wall 6, the center or around the center of the rear end edge 11 is formed as the highest point and the surface thereof slightly and downwardly tilts forward and sideways such that the upper wall 6 forms a smooth surface with a gentle curved surface. The shoe tip wall 3, the left side wall 4, and the right side wall 5 are connected to the outer circumference of the upper wall 6 through a curved portion 12 without forming an angular portion.

As described above, the first woven fabric 9 is bonded or adheres to the upper surface of the upper wall 6 without covering the curved portion 12 connecting the upper wall 6 and the other walls (i.e., the shoe tip wall 3, the left side wall 4, and the right side wall 5). Here, the outer skin constituting the appearance of the footwear and is attached to the shoe sole is referred to as an upper. The upper is configured by sewing a sheet such as leather and is formed in a three-dimensional bag shape in accordance with a foot shape by using a shoe last (wooden last) and an insole. When forming the upper, the lower end portion of the upper is pulled to and fixed to the shoe sole (i.e., lasting), and then the upper is tightened to the shoe last installed with the toe box 1 so as to shape a foot insertion part.

During the above mentioned lasting process, the outer circumference part of the outer skin (also referred to as “upper leather”) including the toe part is pulled to the shoe sole. Accordingly, the outer skin is made contact with the surface of the toe box 1. At this moment, the outer skin is pulled to the shoe sole so as to prevent a wrinkle from being formed on and around the toe part. Accordingly, the lasting process is executed to keep the appearance of and around the shoe tip and to hold the toe box 1. When the outer skin placed on the surface of the toe box 1 is pulled and tightly made contact with the toe box 1, a resistance force against the tension caused by the pulling may be generated due to the friction thereon. That is, if the toe box 1 has a smooth surface, the outer skin may easily slip and therefore a resistance force against the tension is relatively low. On the other hand, if the toe box 1 has a rough and irregular surface, the resistance force against the tension increases and therefore the lasting process may become insufficient. Especially, the curved portion 12 connecting the tip wall 3, the left side wall 4, the right side wall 5, and the upper wall 6 may have a too strong pressing force. Thus, if the toe box 1 has a rough surface, the lasting process may become insufficient. Therefore, in order to avoid having a rough surface on the curved portion 12, the curved portion 12 is not covered by the first woven fabric 9. In other words, the first woven fabric 9 is provided on the upper surface of the upper wall 6 except for the curved portion 12.

Next, results of the impact resistance test on the above-described toe box 1 are described. The test is carried out to determine whether the toe box 1 meets the requirements for the CSA standards (120 J). In the test, a cylindrical striker ST that has a hemispherical tip of 25.4 mm (i.e., 1 inch) radius and is attached with a weight of 12 kg is dropped from a height of 1 m. Here, the diameter of the cylindrical part of the striker ST is 25.4 mm (i.e., 1 inch). A Table 1 shows the results of the impact resistance tests carried out on toe box bodies (samples A to D). Each of the toe box bodies used as the samples A to D has the same shape and is made of the same material as each other, but is attached with different woven fabrics from each other, as shown in the Table 1. Note that the toe box body is made of a material obtained by adding glass fibers to the nylon 6 at the volume ratio of 40%.

TABLE 1
			DEFORMATION
			AMOUNT/
SAM-	FABRIC	THICKNESS/	DEFORMATION
PLE	MATERIAL	DIAMETER	RATE	CRACK
A	NYLON	0.3 mm/	18.8 mm/42.7%	NO
		0.021 mm
B	NYLON	0.3 mm/	19.0 mm/43.2%	NO
		0.043 mm
C	POLYESTER	0.2 mm/	19.9 mm/45.2%	YES
		0.028 mm
D	NONE	—	22.1 mm/50.2%	YES

The test result for each of the samples is explained below.

In the sample A, a woven fabric formed of nylon resin fibers having a wire diameter of 0.021 mm (actual value) was attached to the front and back surfaces on the upper wall of the toe box body with the adhesive agent. The thickness of the woven fibers was 0.3 mm For the test, a cylindrical oil clay N was put inside the toe box body (having a height of 44 mm for the inner surface of the opening part), and the striker was dropped onto the toe box body. During the test, a deformation amount of the oil clay N (i.e., inner surface height 44 mm—remaining height of oil clay N) and a presence of damage on the toe box body were examined (see FIG. 8). As the test results of the sample A, the deformation amount of the toe box body, which was determined from the deformation amount of the oil clay N, was 18.8 mm That is, the deformation rate relative to the total height 44 mm was about 42.7%. Through the impact resistance test on the sample A, the toe box body did not have a physical damage, as shown in FIGS. 4A, 4B. Note that FIG. 4A shows an external view of the front surface of the sample A, while FIG. 4B shows an external view of the back surface of the sample A.

In the sample B, a woven fabric formed of nylon resin fibers having a wire diameter of 0.043 mm (actual value) was attached to the front and back surfaces on the upper wall of the toe box body with the adhesive agent. The thickness of the woven fibers was 0.3 mm Similar to the sample A, the sample B was attached with the woven fabric of nylon resin fibers, but the wire diameter of the nylon resin fibers is thicker than that of the sample A. As the test results of the sample B, the deformation amount of the toe box body, which was determined from the deformation amount of the oil clay N, was 19.0 mm. That is, the deformation rate relative to the total height 44 mm was about 43.2%. Through the impact resistance test on the sample B, the toe box body did not have a physical damage, as shown in FIGS. 5A, 5B. Note that FIG. 5A shows an external view of the front surface of the sample B, while FIG. 5B shows an external view of the back surface of the sample B.

In the sample C, a woven fabric formed of polyester fibers (Product Number: T5110S, NT251) having a wire diameter of 0.028 mm (actual value) is attached to the front and back surfaces on the upper wall of the toe box body with the adhesive agent. The thickness of the woven fiber was 0.2 mm As the test results of the sample C, the deformation amount of the toe box body, which was determined from the deformation amount of the oil clay N, was 19.9 mm That is, the deformation rate relative to the total height 44 mm was about 45.2%. Through the impact resistance test on the sample C, the toe box body was cracked, as shown in FIGS. 6A, 6B (see Cl in FIG. 6A and C2 in FIG. 6B). Note that FIG. 6A shows an external view of the front surface of the sample C, while FIG. 6B shows an external view of the back surface of the sample C.

The sample D was formed such that the JIS standards, S-division (70 J) are satisfied. Here, the sample D was a bare toe box body having no woven fabric attached thereto. As the test results of the sample D, the deformation amount of the toe box body was 22.1 mm That is, the deformation rate relative to the total height 44 mm was about 50.2%. Through the impact resistance test on the sample D, the toe box body was cracked, as shown in FIGS. 7A, 7B (see D1 in FIG. 7A and D2 in FIG. 7B). This means, the sample D can bear the impact load of the JIS standards, S-division (70 J), but cannot bear the impact load of the CSA standards (120 J), which exceeds the impact load of the S-division by 50 J. Note that FIG. 7A shows an external view of the front surface of the sample D, while FIG. 7B shows an external view of the back surface of the sample D.

As mentioned above, the deformation rate of the sample A was about 42.7% and of the sample B was about 43.2%, and in these cases, the toe box bodies did not have a physical damage. However, the deformation rate of the sample C was 45.2% and of the sample D was about 50.2%, and in these cases, the toe box bodies had the cracks on the toe box body. The results insist that, compared to other woven fabrics, the woven fabric made of the nylon resin fibers can reduce a deformation amount against an impact load, and therefore can prevent the toe box from being damaged.

The tensile strength of the non-reinforced nylon 66 is 48 to 67 MPa, and the tensile strength of the nylon 6 is 41 to 166 MPa. The tensile strength of polyethylene is 23 to 31 MPa. This means, in terms of the mechanical properties considered to be involved in deformation resistance, nylon is about twice better than polyethylene. In other words, since nylon has relatively a high tensile strength, the nylon (woven fabric) attached to the toe box body acts like a trampoline against an impact load. Accordingly, it is possible to reduce the deformation amount of the toe box body attached with a woven fabric of nylon resin fibers.

In the toe box 1 of the disclosure, the woven fabric made of the nylon resin fibers is simply attached by the adhesive agent. Thus, the toe box body does not receive any structural influence which may damage the surface of the toe box body, and therefore the toe box 1 of the disclosure does not impair the strength and properties of the toe box body. Here, in order to attach the woven fabric on the toe box body, it is possible to place the woven fabric inside the mold prior to molding and then form the toe box body by injection molding, or form the toe box body by pressure molding or compression molding the heated resin like forging. However, with the above methods, the woven fabric placed inside the mold may be moved by the applied pressure. Thus, it makes difficult to integrally provide the woven fabric to the toe box body during the molding process. In this embodiment, the toe box body is made of the nylon resin containing the glass fibers. If the nylon resin is heated to be melted or softened, the performance of the woven fabric made of the nylon resin is deteriorated or impaired. Therefore, it is not preferable to provide the woven fabric on the toe box body through a molding process. Further, if the woven fabric is attached to the toe box body through a heating process, the surface of the toe box body may become rough and uneven due to the texture of the woven fabric, resulting in a decrease of the strength or hardness of the toe box.

The disclosure relates to the toe box installed in the shoe tip of work footwear such as safety footwear for protecting a toe, and provides a structure and a manufacturing method of a resin toe box having a high impact resistance. Specifically, in the disclosure, the embodiment includes the toe box body formed to have the impact resistance that can satisfy the JIS standards, S-division (70 J), and the upper wall of the toe box body is attached or covered with nylon resin fibers. Accordingly, the toe box has an excellent and reinforced impact resistance. It should be noted that the mechanical properties of the toe box body are not deteriorated or impaired by attaching the nylon resin fiber thereon. Further, as shown in the test results, the impact resistance of the toe box body is significantly improved only by attaching the nylon resin fiber. The toe box body of the embodiment is made of the resin reinforced by adding the glass fibers. However, if the surface of such a toe box has a rough and/or uneven surface, cracks are likely to occur on the surface due to an impact. Therefore, the surface of the toe box body in this embodiment is formed to have a smooth surface having no sharp edge or irregularities. Additionally, the toe box of this disclosure is obtained by simply attaching the woven fabric of the nylon resin fibers by the adhesive agent. Therefore, it will not damage the surface of the toe box body. Further, the embodiment does not use a solvent or an adhesive agent that affects the composition of the toe box body. Therefore, attaching the woven fabric to the toe box body according to this embodiment will not impair the strength inherent to the toe box body.

In the disclosure, the woven fabric made of the nylon resin fibers is attached to the toe box body by the urethane-based adhesive which is applicable and preferable to attach a nylon-based material. As both of the toe box body and the woven fabric attached thereto are made of nylon, the urethane-based adhesive can improve the adhesive strength between the toe box body and the woven fabric.

In the impact resistance test of this disclosure, the side wall of the toe box 1 on the little finger side is extended rearward so as to form the extended side wall portion 8. However, it should be understood that similar results should be available even if a normal-shaped toe box (e.g., a toe box formed in accordance with the “JIS T 8101” of the Japanese Industrial Standard (JIS)) is used in the impact resistance test.

In this embodiment, as one of preferable examples to improve the impact resistance performance, the woven fabric made of nylon resin fibers is attached to the front and back surfaces on the upper wall of the toe box body through an adhesive layer formed by the adhesive agent. Further, it is possible to form the upper wall as a multi-layered structure with the simple process and without a large facility. Owing to the strength of each layer in the multi-layered structure and owing to the interaction between the each layer, the impact resistant performance of the toe box is improved.

Although the present invention has been described in terms of an exemplary embodiment, it should not be limited thereto. It should be appreciated that variations or modifications may be made in the embodiment described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims.

Claims

1. A toe box installed in a shoe tip of work footwear for protecting a toe, comprising:

a toe box body integrally formed by a shell body to cover the toe, the shell body connecting a tip wall, a left side wall, a right side wall, and an upper wall with a smoothly curved surface, and the tip wall, the left side wall, the right side wall, and the upper wall being made of a synthetic resin material,

wherein a front surface and a back surface of the upper wall are formed as a smooth surface, and

wherein the front surface of the upper wall is provided with a woven fabric formed of nylon resin fiber through an adhesive layer.

2. The toe box according to claim 1, wherein the back surface of the upper wall is provided with a woven fabric formed of the nylon resin fiber through an adhesive layer.

3. The toe box according to claim 1, wherein the toe box body is formed of nylon resin reinforced by a glass fiber.

4. The toe box according to claim 2, wherein the toe box body is formed of nylon resin reinforced by a glass fiber.