WO1997019609A1

WO1997019609A1 - Toe caps for footwear

Info

Publication number: WO1997019609A1
Application number: PCT/AU1996/000764
Authority: WO
Inventors: Norman William Macleod
Original assignee: Norman William Macleod
Priority date: 1995-11-28
Filing date: 1996-11-28
Publication date: 1997-06-05

Abstract

A toe cap for a safety boot is disclosed. The toe cap is formed from a blank comprising a laminate of thermosetting resin which is shaped and hardened by a pressure moulding operation. The laminate comprises two layers of polyester or epoxy resin having a layer of fibre sandwiched therebetween. In one form the toe cap is formed from two such laminates superimposed on each other. The fibre is glass fibre, carbon fibre or metallic fibre which is either randomly distributed, linearly distributed, or in the form of a mat. A method of making the toe cap is also disclosed.

Description

TOE CAPS FOR FOOTWEAR

This invention relates to toe caps for footwear.

This invention relates particularly to protective toe caps for safety boots and it will be convenient to hereinafter describe the invention with reference to this example application. It is to be clearly understood however that the invention is capable of broader application

A feature of the safety boots required to be worn by workers in many industries is that they must have a strong rigid toe cap for resisting injury to the toes of a wearer should a heavy object fall thereon. Toe caps for safety boots are required to satisfy certain objective strength criteria, for example European Standard BS EN 334:1993 and Australian Standard AS 2210.2, the contents of which are incorporated herein by reference.

Protective toe caps for boots have up to now been made of a single unitary piece of steel. Steel confers on the toe cap the strength that enables it to effectively fulfil its protective function. Such steel toe caps however suffer from the drawback that they are relatively heavy.

While plastic toe caps for shoes are known, these plastic toe caps, which are generally manufactured by injection moulding, comprise a single unitary article of homogeneous plastic material. It is not possible to incorporate two discrete plastic articles into an injection moulded toe cap. Such injection moulded plastic toe caps suffer from the disadvantage that they are generally not strong enough to act as protective toe caps for safety shoes.

It would be advantageous to be able to provide a toe cap which had a strength comparable to that of a one piece unitary steel toe cap but which was also substantially lighter than such a steel toe cap. According to an aspect of this invention there is provided a toe cap for an item of footwear, the toe cap including a laminate including at least two layers of plastic laminated to each other.

By laminating at least two layers of plastic together, a plastic toe cap having a greater strength is obtained than that achieved where the toe cap is made of a single piece of injection moulded plastic.

The laminate preferably comprises two layers of plastic having a layer of fibre sandwiched therebetween.

Optionally the toe cap comprises a further layer of fibre laminated to said laminate. In one embodiment, the further layer of fibre is metallic fibre, e.g. fly wire.

Further optionally the toe cap comprises two or more said laminates in a superimposed relationship, e.g. to provide a toe cap with four layers of plastic and two layers of fibre.

Typically the toe cap contains a total of two to eight layers of plastic and one to three layers of fibre. Preferably the toe cap contains a total of two to four layers of plastic and one to two layers of fibre.

Preferably the layers of plastic are made of thermosetting resin, e.g. polyester or epoxy resin. The different layers may be made of different plastic material or else they may be made of the same plastic material.

The fibre may be either randomly distributed, linearly distributed, or in the form of a woven or non-woven mat. Further the fibre may be glass fibre, carbon fibre, e.g. KEVLAR, or metallic fibre, e.g. fly wire. ln one embodiment, where the fibre is in the form of a woven mat, the warp strands are of one material, e.g. metallic fibre, and the weft strands are of another material, e.g., non-metallic fibre.

In an alternative embodiment, the toe cap may further include a metal insert together with said laminate.

The metal insert acts to increase the strength of the toe cap. More specifically, it increases the resistance of the toe cap to collapse when a heavy object is dropped onto it.

The metal insert may be substantially planar or it may be shaped. Typically the insert only extends across a portion of the toe cap so as to reduce the costs associated with the shaping thereof.

Typically the metal insert is a carbon steel which optionally may be hardened and tempered. Advantageously the metal insert is corrugated so as to increase the strength thereof in a load direction.

Further alternatively the laminate may contain at least one layer of fibre reinforced plastics and at least one layer of plastics without fibre. Layers of fibre reinforced plastic material are generally stronger than layers of plastic without fibre reinforcing. However fibre reinforcing is expensive and thus one or more of the plastic layers will only be fibre reinforced if this is necessary to confer the necessary strength on the toe cap.

In one embodiment the toe cap comprises a layer of fibre reinforced plastic laminated to a layer of plastic which is free of fibre. In an alternative embodiment, the toe cap comprises a layer of fibre reinforced plastic sandwiched between two layers of plastic which are free of fibre. Where appropriate adhesive may be used to bond the various plastic layers to each other. Any suitable adhesive may be used. The adhesive may also bond the metal insert to the plastic layers.

This invention also extends to an item of footwear having a toe cap including a laminate including at least two layers of plastic laminated together.

Typically the item of footwear is a boot, for example a safety boot. The toe cap of the boot may incorporate any one or more of the features of the toe cap described above with reference to the first aspect of the invention.

According to another aspect of this invention there is provided a method of forming a toe cap including the steps of providing a blank including a laminate having at least two plastic layers, and then forming the blank into a toe cap.

Advantageously the method includes the further step of forming the laminate.

The step of forming the laminate may include the step of forming separate layers of plastic from resin paste prior to the step of laminating the layers to each other.

Preferably the step of forming the laminate includes: forming one layer of plastic material from a resin paste; applying a layer of fibre to said one layer; forming a further layer of plastic material from a resin paste; and applying said further layer to said one layer such that the layer of fibre is sandwiched between said one and further layers.

Advantageously said one and further layers of plastic material are made of thermosetting resin, e.g. polyester or epoxy resin. The fibre may be either randomly distributed, linearly distributed, or in the form of a woven or non-woven mat.

Typically said step of forming the blank into a toe cap includes a pressure molding operation to shape and harden the blank which includes said laminate.

Optionally the blank may include a layer of fibre in addition to said laminate.

Further optionally the blank may comprise two to four said laminates superimposed on each other.

Advantageously, the laminated plastic layers are heated to a temperature of 120 - 140°C during the pressure moulding operation.

Alternatively the method may include extruding one layer through an extrusion die, applying a particulate plastic to the extruded layer, and then applying heat and pressure to the particulate plastic layer to fuse such plastic layer and thereby laminate it to the extruded plastic layer.

Further, alternatively the method may include the step of extruding a layer of plastic through an extrusion die and then laminating the layer of plastic directly onto a pre-formed layer of fibre reinforced plastic.

Instead of extruding the separate layers, the method may include pre¬ heating and shaping the individual layers, e.g. from thermosetting plastics, and then allowing them to set in hot or cold moulds.

A toe cap in accordance with this invention may come in a variety of forms. It will be convenient to hereinafter describe in detail several example embodiments of the invention with reference to the accompanying drawings. It is to be clearly understood however that the specific nature of this description does not derogate from the generality of the preceding statements of invention. In the drawings:

Fig. 1 is sectional side elevation of a toe cap in accordance with the invention;

Fig. 2 is top plan view of the toe cap of Fig. 1 ;

Fig. 3 is a sectional view of part of a toe cap in accordance with one embodiment of the invention;

Fig. 4 is a sectional view of part of a toe cap in accordance with another embodiment of the invention;

Fig. 5 is sectional view of part of a toe cap in accordance with another embodiment of the invention;

Fig. 6 is a schematic flow sheet of a process for making a laminate for use in making the toe cap of Fig. 1 ;

Fig. 7 is a schematic sectional front elevation of a press for molding a toe cap from a blank;

Fig. 8 is a front three-dimensional view of a toe cap in accordance with this invention;

Fig. 9 is an exploded rear three-dimensional view of the toe cap of Fig. 8;

Fig. 10 is a sectional view through part of the toe cap of Fig. 8, section through X - X; Fig. 11 is a sectional view of part of a toe cap in accordance with another embodiment of the invention, the section being of the same general nature as that in Fig. 10;

Fig. 12 is a front three-dimensional view of a toe cap in accordance with another embodiment of this invention;

Fig. 13 is a front three-dimensional view of a toe cap in accordance with another embodiment of this invention; and

Fig. 14 is a three-dimensional view of a toe cap in accordance with another embodiment of this invention.

Fig. 1 is a cross sectional profile of a toe cap 1 in accordance with a preferred embodiment of the invention. The front of the toe cap 1 is indicated by the numeral 2 and the rear by the numeral 3. Fig. 2 shows a plan view of the same toe cap 1. The drawings indicate the design configuration of a preferred embodiment of the toe cap. However, no details of the laminate construction of the toe cap are shown in these schematic drawings. It is to be appreciated that the shape of the toe cap will vary according to aesthetic and fashion requirements.

Fig. 3 illustrates a cross section of part of a toe cap in accordance with one embodiment of the invention. The cross section shows details of the laminate 4 making up the toe cap 1. Specifically the laminate comprises an inner layer 5 of epoxy or polyester thermosetting resin and an outer layer 6 of polyester or epoxy thermosetting resin with a layer of fibre 7 sandwiched therebetween. The fibre 7 is either randomly distributed, linearly distributed, or in the form of a mat. Typically the fibre 7 is glass fibre but it could also be carbon fibre, e.g. KEVLAR or a combination of any of these fibres. Fig. 4 illustrates a cross-section of the laminate making up a toe cap in accordance with another embodiment of the invention. The only difference between this laminate and that illustrated in Fig. 3, is the further layer of fibre 9 super-imposed on the laminate of the Fig. 3 toe cap. This layer of fibre 9 may be a metallic fibre, e.g. a fly wire.

Fig. 5 illustrates a cross section of the laminate making up another embodiment of the toe cap. This laminate is very similar to that illustrated in Figs. 3 and 4. The only difference is that the toe cap is formed from two super- imposed laminates 4 of the type shown in Fig. 3. Thus in this embodiment there are two pairs of plastic layers 5 and 6 each of which has a layer of fibre 7 sandwiched therebetween.

The process for manufacturing the toe cap comprises two discrete steps, namely the manufacture of the molding compound or basic laminate from which the toe cap is formed, and then the pressure molding operation which shapes the actual toe cap from the molding compound.

Fig. 6 illustrates apparatus 20 for forming the sheet molding compound or laminate. The apparatus 20 comprises broadly two tanks 21 and

22 for dispensing resin paste and a fibre dispenser 23 for dispensing fibre. A layer of resin 24 from the resin tank 21 is guided by a carrier film 25 underneath the fibre dispenser 23 where it receives a layer of fibre 27. The layer of resin

24 is then passed into engagement with a layer of resin 28 from the resin tank 22 by a further carrier film 26 to form the basic laminate 29 which forms the molding compound. The laminate 29 comprising layers of plastic 24 and 28 with a layer of fibre 27 sandwiched therebetween is then passed through the nip region of four pairs of rollers 30 arranged in series. This performs an appropriate degree of compaction. The laminate 29 is then typically rolled into rolls for storage prior to use in the actual molding operation which shapes the toe cap. The resin tanks 21 and 22 contain in addition to the thermosetting resins, fillers, catalyst and optionally colouring agents. The resins in the tank are typically slightly above ambient temperature.

Fig. 7 illustrates the molding press 40 for forming the toe cap 1 from the molding compound. The mold 40 includes a male component 41 and a female component 42 which receives the male component 41. The male component 41 is powered by a hydraulic press 43 which can typically generate a hydraulic pressure of 1000 psi.

In use, a blank 44 including at least one appropriately shaped piece of molding compound is placed in the female component 42. Most typically the blank 44 comprises a piece of molding compound superimposed on a layer of fibre, e.g. steel fibre, or two pieces of molding compound superimposed on each other. Naturally the carrier films 25 and 26 on each side of the molding compound are removed prior to the compound being placed in the female component 42.

The female component 42 is heated to a temperature of 120°C to 140°C to render the plastic of the laminate malleable. The male component 41 is then urged into deforming engagement with the blank under pressure to cause the thermosetting plastics to deform then set and form the toe cap.. At the appropriate time the male component 41 is withdrawn from the female component 42 and the formed toe cap is removed from the press.

Figs. 8 to 10 illustrate a further embodiment of a toe cap 51. The cap 51 comprises two layers of plastic laminated to each other, namely an inner layer 52 and an outer layer 53.

The inner layer 52 is made of a fibre reinforced plastic such as fibre glass, carbon fibre and/or KEVLAR. The outer layer 53 comprises a plastic layer which is free of fibre, the plastic typically being a polycarbonate. As shown in the drawings, each of the layers is formed into the shape of a toe cap prior to being laminated together. Typically the layers 52 and 53 are formed by extrusion although other forming operations are also possible. Each layer comprises broadly a vertically extending wall portion 54, a horizontally extending top portion 55, and an inwardly projecting flange-like anchoring portion 56 at the bottom of the wall portion 54. The layers 52 and 53 are firmly laminated together, typically by means of an adhesive. Suitable adhesives would be well known to persons skilled in the art and will not be described in further detail here.

The toe cap illustrated in Fig. 11 is basically the same as that illustrated in Fig. 10. The main difference is that this toe cap 51 comprises three layers rather than two. The same reference numerals will be used to refer to the same components unless otherwise specified. In Fig. 11 a layer of fibre reinforced plastic 52 is sandwiched between inner and outer layers of plastic which do not contain fibre. As with the Fig. 8 embodiment the fibre reinforced plastic will typically be fibre glass, carbon fibre or KEVLAR. The plastic without fibre will typically be a polycarbonate.

The toe caps illustrated in Figs. 12 to 14 are very similar to the toe caps illustrated in Figs. 8 to 10. The main difference is that the toe caps include a shaped metal insert 56 sandwiched between the two plastic layers 52 and 53.

The different embodiments illustrated in Figs. 12 to 14 have metal inserts of differing configurations. The metal insert in Fig. 12 extends across the horizontally extending top portion of the toe cap. The insert in Fig. 13 extends around the vertically extending wall portion of the toe cap. The insert in Fig. 14 has a hoop-like configuration and is positioned with the hoop extending vertically towards the leading edge of the toe cap. The metal inserts have a relatively simple shape to reduce the costs of machining thereof. A carbon steel which has been hardened and tempered is the most preferred material for the insert. The steel has corrugations extending in the directions indicated in the drawings to increase the strength thereof. The purpose of the metal insert is to increase the resistance of the toe cap to collapse or deformation when heavy objects are dropped thereon from above.

It is an advantage of the toe caps described above that they are sufficiently strong to form a toe cap for fitting to a safety boot. The toe caps described above are substantially stronger than the known unitary one-piece plastic toe caps formed by injection moulding.

In some applications it is necessary for all components of a boot to be non-metallic. For example, it is highly desirable that army boots do not contain any metallic components, one reason being that boots containing metal may unwittingly set off magnetically activated land mines. Some of the embodiments described above do not contain any metal and thus would be suitable for this application.

It is to be understood that various alterations, modifications, and/or additions may be introduced into the constructions and arrangements of the components previously described without departing from the ambit of the invention disclosed herein.

Claims

1. A toe cap for an item of footwear including a laminate including at least two layers of plastic laminated to each other.

2. A toe cap according to claim 1 , wherein the laminate includes two layers of plastic having a layer of fibre sandwiched therebetween.

3. A toe cap according to claim 2, wherein the fibre is randomly distributed, linearly distributed, or in the form of a woven or non-woven mat.

4. A toe cap according to claim 2 or claim 3, wherein the fibre is glass fibre, carbon fibre, or metallic fibre.

5. A toe cap according to any one of claims 1 to 4, wherein the layers of plastic are made of polyester or epoxy resin.

6. A toe cap according to claim 2 or claim 3, wherein the fibre is in the form of a woven mat, the warp strands of which are of one material and the weft strands of which are of another material.

7. A toe cap according to any one of claims 1 to 5, wherein two or more said laminates are superimposed on each other and laminated to each other.

8. A toe cap according to any one of claims 1 to 5, wherein said laminate is superimposed on one or more layers of fibre and laminated thereto.

9. A toe cap according to claim 1 , wherein the toe cap contains a total of two to four layers of plastic and one to two layers of fibre.

10. A method of forming a toe cap including the steps of providing a blank including a laminate having at least two plastic layers, and then forming the blank into a toe cap.

11. A method of forming a toe cap according to claim 10, wherein the method includes the further step of forming the laminate.

12. A method of forming a toe cap according to claim 11 , wherein the step of forming the laminate includes the step of forming separate layers of plastic from resin paste prior to laminating the layers to each other.

13. A method of forming a toe cap according to claim 11 , wherein the step of forming the laminate includes: forming one layer of plastic material from a resin paste; applying a layer of fibre to said one layer; forming a further layer of plastic material from a resin paste; and applying said further layer to said one layer such that the layer of fibre is sandwiched between said one and further layers.

14. A method of forming a toe cap according to any one of claims 10 to 13, wherein said one and further layers of plastic material are made of polyester or epoxy thermosetting resin.

15. A method of forming a toe cap according to any one of claims 10 to 14, wherein the fibre is either randomly distributed, linearly distributed, or in the form of a woven or non-woven mat.

16. A method of forming a toe cap according to any one of claims 10 to 15, wherein said step of forming the toe cap includes a pressure molding operation to shape and harden the blank which includes said laminate.

17. A method of forming a toe cap according to claim 16, wherein the blank includes a layer of fibre in addition to said laminate.

18. A method of forming a toe cap according to claim 16, wherein the blank comprises two said laminates superimposed on each other.

19. A method of forming a toe cap according to claim 16, wherein the blank comprises two to four said laminates superimposed to each other.

20. A method of forming a toe cap according to any one of claims 16 to 19, wherein the laminate is heated to a temperature 120°C to 140°C during the pressure molding operation.

21. A toe cap for an item of footwear substantially as herein described with reference to any one of the embodiments illustrated in the accompanying drawings.

22. A method of forming a toe cap substantially as herein described with reference to any one of the embodiments illustrated in the accompanying drawings.