GB2060350A

GB2060350A - Safety footwear

Info

Publication number: GB2060350A
Application number: GB7925248A
Authority: GB
Original assignee: Orme Polymer Engineering Ltd
Current assignee: Orme Polymer Engineering Ltd
Priority date: 1979-07-19
Filing date: 1979-07-19
Publication date: 1981-05-07

Abstract

A safety boot, to protect a wearer's foot from injury owing to piercing or crushing of the boot, is made by forming a casing (10) by rotational moulding a PVC plastisol material, positioning a perforated steel toe-cap (12) within the casing after the material of the casing has gelled but before it has fully cured, and rotationally moulding a lining (14) from a PVC plastisol material over the inside of the casing to wholly enclose the toe-cap. After introduction of a smoothing layer (16) into the bottom of the boot shell so formed, a steel insole plate (22) is positioned and an insole coating (24) applied to cover the insole plate. <IMAGE>

Description

SPECIFICATION Safety footwear This invention is concerned with safety footwear, in particular boots and shoes which are constructed with some reinforcement, for example of steel, to protect a wearer's foot from injury owing to piercing or crushing of the footwear.

Safety boots are known which comprise reinforcement in the form of steel toe-caps and insole plates. The boots are made of leather or synthetic leather materials by essentially conventional shoemaking techniques, and the steel reinforcement is incorporated in the soles and uppers of the boots during construction.

In order to meet certain safety standards, it is desirable that reinforcing members in safety footwear are wholly enclosed by the remaining structure of the footwear. Furthermore, where the reinforcement comprises both a toe-cap reinforcing member and an insole reinforcing member it may be specified that the two members be incorporated into the footwear separately and not joined together; one known practice, which is unacceptable by this standard, is to incorporate two steel members which are joined together by spot welding.

According to the invention there is provided a method of manufacturing an article of safety footwear comprising the steps of moulding a casing of the article of a plastics material, positioning a reinforcing member within the casing, and moulding a lining of a plastics material over an inside surface of the casing so that the reinforcing member becomes wholly enclosed by the casing and the lining.

The casing and the lining may each be formed by any suitable plastics moulding process, but are pref erablyformed buy a rotational moulding process or a slush moulding process. To avoid problems of air entrapment between the reinforcing member and the casing, it may be found necessary to employ a reinforcing member that is porous or perforated to permit the passage of air thereth rough. Perforations may be in the range of 1 mm to 6 mm in diameter.

The casing, and the lining, may be of a PVC plastics material and be moulded from a PVC plastisol material. Where the moulding material is a PVC plastisol, the reinforcing member is preferably positioned within the casing after the material of the casing has gelled but before it has fully cured.

In one prefered method, two reinforcing members are incorporated into the article, one member being in the form of a toe-cap and the other in the form of an insole plate. The toe-cap is inserted after moulding the casing, so as to be wholly enclosed by the casing and the lining. After moulding the lining a smoothing layer is formed on an inside bottom surface of the lining, to smooth irregularities (including, for example, a heel cavity) in the bottom surface, and the insole plate is positioned on the smoothing layer.

An insole coating is then applied over the insole plate so that the insole plate becomes wholly enclosed by the insole coating and the smoothing layer, or the insole coating, the smoothing layer and a portion of the lining. Each of the smoothing layer and the insole coating may be of a cold-setting polyurethane material.

The reinforcing member, or members, may be of a metal, which metal may be steel.

There now follows a description, to be read with reference to the accompanying drawing, of a method which illustrates the invention by way of example.

The accompanying drawing shows, in crosssection, a safety boot made by the illustrative method.

An electro-formed, copper-nickel, boot mould (not shown) is procured. The mould is in two parts, with one part, a closure plate, secured to the remainder of the mould around a welt-forming region of the mould. With the closure plate removed the mould is charged with a quantity of a PVC plastisol material, and the closure plate is then secured to close the mould. Formation of an outer casing 10 of a boot by a conventional rotational moulding process is then commenced, the mould being heated and rotated to about two axes (which extend transversely of one another) to spread the plastisol over the inside surface of the mould.

When the plastisol has gel led, but before it has fully cured, the mould is opened, whilst still hot, by removal of the closure plate. The material of the outer casing 10, which still adheres to the mould, has to be torn at the region of the welt to allow the closure plate to be removed. A reinforcing member in the form of a perforated steel toe-cap 12 is primed with a priming paint, to improve the adhesion of PVC, and then dip-coated with a PVC plastisol material. The primed and dip-coated toe-cap is then positioned within the outer casing 10 to adhere to an inside surface of a toe portion of the casing. Before re-closure of the mould a further charge of a PVC plastisol material is put into the mould, and the closure plate is then replaced to close the mould.

The perforations in the toe-cap 12 are small, i.e.

around 3 mm in diameter, as otherwise the toe-cap would not provide adequate protection against piercing of the boot. However some perforation of the toe-cap is desirable in moulding the boot in order to avoid problems of gas entrapment between the toe-cap and the outer casing.

Rotational moulding is then continued, curing of the outer casing 10 proceeding and the further charge of PVC plastisol put into the mould forming a lining 14 over the inside surface of the casing 10 and the toe-cap 12. The torn welt region of the outer casing quickly mends. The toe-cap becomes wholly enclosed by the casing and the lining, the lining becoming homogeneous with the casing owing to its application before the casing is fully cured.

When moulding of the casing 10 and the lining 14 is complete, with the PVC material fully cured, the mould is opened and the boot moulding removed. A portion of the moulding is cut away to open the neck of the boot moulding. A cold-setting polyurethane composition is then poured in liquid form into the bottom of the moulding to form a smoothing layer 16 on an inside bottom surface of the lining. The smoothing layer fills a heel cavity 18 and other irregularities, for example irregularities 20 resulting from a tread pattern moulded into the outer casing 10.

When the material of the smoothing layer has set to a solid state, a second reinforcing member, in the form of a steel insole plate 22, is coated on both sides with a metal-bonding adhesive and positioned on the smoothing layer 16. An insole coating 24 of a liquid, cold-setting, polyurethane composition is then applied over the insole plate so that the insole plate becomes wholly enclosed by the insole coating, the smoothing layer 16, and a portion of the lining 14. The insole coating sets to a solid state.

Claims

1. A method of manufacturing an article of safety footwear comprising the steps of moulding a casing of the article of a plastics material, positioning a reinforcing member within the casing, and moulding a lining of a plastics material over an inside surface of the casing so that the reinforcing member becomes wholly enclosed by the casing and the lining.

2. A method according to Claim 1 in which the casing is formed by a rotational moulding process or a slush moulding process.

3. A method according to either of Claims 1 and 2 in which to permit the passage of air therethrough the reinforcing member is porous or perforated.

4. A method according to Claim 3 in which the reinforcing member is perforated with perforations in the range of 1 mm to 6 mm in diameter.

5. A method according to any one of Claims 1 to 4 in which the casing is of a PVC plastics material.

6. A method according to Claim 5 in which the casing is moulded from a PVC plastisol material, and the reinforcing member is positioned within the casing after the material of the casing has gelled but before it has fully cured.

7. A method according to any one of Claims 1 to 6 in which the reinforcing member is in the form of a toe-cap.

8. A method according to Claim 7 in which after moulding the lining a smoothing layer is formed on an inside bottom surface of the lining and a reinforcing member in the form of an insole plate is positioned on the smoothing layer.

9. A method according to Claim 8 in which an insole coating is applied over the insole plate so that the insole plate becomes wholly covered by the insole coating.

10. A method of manufacturing an article of safety footwear, which method is substantially as hereinbefore described with reference to the accompanying drawing.

11. An article of safety footwear manufactured by a method according to any one of Claims 1 to 9.

12. An article of safety footwear substantially as hereinbefore described with reference to the accompanying drawing.