PROTECTIVE MATERIAL

Abstract: A method of making a semi-rigid protective material for use on a body, comprises the steps of providing a sheet of flexible polymer material (1) of high impact strength, such as low or high density polyethylene or polypropylene, providing one or more pieces of high density polyethylene foam, placing and or attaching said high density polyethylene foam piece (3) or pieces on or to said sheet at locations where additional body protection may be required, covering said sheet and high density polyethylene foam (3) with a layer (2) of low density foamed plastics material, such as polyethylene or EVA copolymer; laminating said material by heating at a temperature between 110 and 200 DEG C for approximately 2 minutes with a vacuum blanket pressure of 0.2 bar, and then moulding said laminate to shape at a temperature between 80 DEG C and 160 DEG C for 2 minutes with a vacuum blanket pressure of 0.4 bar.

Description: PROTECTIVE MATERIAL The present invention relates to protective material and a method of making it. The material is particularly useful for body protection for both humans and animals. Examples are particularly useful for protection against sporting injuries such as in the fields of cricket, football, yachting and motorcycle racing or for protection against attack. For example, the protective material may be formed into shin pads, shoulder pads, arm pads, protective life jackets, body armour, lumbar protectors or back or chest protectors. It is known to provide protectors of the above types but in general these comprise a very rigid portion. While this may protect against some degrees of injury, there are occasions when the rigid protection snaps or breaks and in fact is likely then to aggravate any injury received. It is an object of the present invention to be able to provide body protectors of protective material which give a reasonable degree of protection and which are not harmful should they become damaged. It is the main object of the present invention to provide a method of making εuch material. According to the present invention there is provided a method of making a semi-rigid protective material for use on a body, comprising the steps of providing a sheet of flexible polymer material of high impact strength, such as low or high density polyethylene or polypropylene, providing one or more pieces of high density polyethylene foam, placing and or attaching said high density polyethylene foam piece or pieces on or to said sheet at locations where additional body protection may be required, covering said sheet and high density polyethylene foam with a layer of low density foamed plastics material, such as polyethylene or EVA copolymer; laminating said material by heating at a temperature between 110 and 200°C for approximately 2 minutes with a vacuum blanket pressure of 0.2 bar, and then moulding said laminate to shape at a temperature between 80°C and 160°C for 2 minutes with a vacuum blanket pressure of 0.4 bar. Other layers of plastics material may also be incorporated into the laminate. The invention also encompasses a laminate made according to the above method. The polymer sheet is preferably of thickness in the region of 1.5 mm. The high density polyethylene foam is preferably of thickness in the region of 3 mm. The low density foam may be of any thickness between 5 and 15 mm, depending on the intended applications of the material. One or more straps may be attached during the method and are preferably located between the high density polyethylene foam layer and the low density foamed plastics material layer. Once the laminate is formed in the mould, it will substantially retain the shape of the mould and therefore fit where appropriate around the body of the wearer. An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: FIGURE 1 shows schematically a back protector embodying the invention; FIGURE 2 shows a shin pad embodying the invention; and FIGURE 3 is a cross-section through a median portion of the shin pad of Figure 2. Referring now to the drawings, and in particular Figure 3, there is shown a cross-section of material made according to the method of the invention. An outer layer 1 comprises a film of low density polyethylene, high density polyethylene or polypropylene, generally of thickness in the region of 1.5 mm. Such materials are sold under the trade names Courthene (Registered Trade Mark) , Hilex (Registered Trade Mark) and Propylex (Registered Trade Mark) . An inner layer 2 is formed of a crosslinked closed cell low density polyethylene or EVA foam. Suitable materials are sold under the trade name Plastazote (Registered Trade Mark) and Evazote (Registered Trade Mark). This inner layer 2 may vary in thickness depending on the function the protector is to perform. For example, in the case of the shin pads it is only 5 mm thick and for the back protector it may be 10 mm thick. In fact, in some cases it may be as much as 15 mm thick. Between the inner and outer layers is a central layer 3 of high density polyethylene foam, generally of thickness in the region of 3 mm. The preferred material for thiε layer is an irradiation crosslinked polyethylene foam sold under the trade name Alveolit (Registered Trade Mark). This central layer 3 is present only over those areas which need most protection, for example over the shin and ankle bones in the shin guard or over the spine and kidneys in the back protector. The material is made by a process of lamination in a vacuum mould. The piece or pieces of high density polyethylene foam are placed onto the layer of plastics film in position as required and the low density foam is placed on top. The assembly is then placed on a flat platen and heated to 110 - 200°C depending on the material of the sheet. For polypropylene, 200° is more appropriate or for polyethylene, lower temperatures are needed. The laminate is formed after two minutes at a vacuum blanket pressure of 0.2 bar when the sheet becomes welded to the low denεity foam around itε edges. The laminate so formed may then be moulded into the required shape in an epoxy vacuum mould preferably operating at a vacuum blanket pressure of 0.4 bar. The moulding time is 2 minutes and the temperature 90°C. The laminate may incorporate other layers. For example, a laminate may incorporate a layer of polycarbonate plastics material, such as is sold under the trade names RIAG or LEXAN. This layer is dispoεed between the inner and outer layers, adjacent to one or other of them. Such a laminate may be effective as body armour, at least against stabbing with a knife or other pointed implement. In such caεeε, the layer of polycarbonate resin may be of a thickness in the region of 3mm. Another alternative, or indeed additional layer may be of a very low density closed cell polymer foam. This can give buoyancy properties to the protective material, enabling it to be used as a protective life jacket. One further layer which may be added is of a medium density open celled polyurethane foam available under the trade name CONFOR. This material is highly absorbent of energy and has a slow rate of recovery after deflection. It can be incorporated within the interior of the laminate and can be shaped to conform with the general outline of the protective article including it, even where the article is quite sharply bent.

Claims: CLAIMS : 1. A method of making a semi-rigid protective material for use on a body, comprising the steps of providing a sheet of flexible polymer material of high impact strength, such as low or high density polyethylene or polypropylene, providing one or more pieces of high density polyethylene foam, placing and or attaching said high density polyethylene foam piece or pieces on or to said sheet at locations where additional body protection may be required, covering said sheet and high density polyethylene foam with a layer of low density foamed plasticε material, εuch as polyethylene or EVA copolymer; laminating said material by heating at a temperature between 110 and 200°C for approximately 2 minutes with a vacuum blanket pressure of 0.2 bar, and then moulding said laminate to shape at a temperature between 80°C and 160°C for 2 minutes with a vacuum blanket presεure of 0.4 bar. 2. A method aε claimed in claim 1 , wherein the polymer sheet is of thickness in the region of 1.5 mm. 3. A method as claimed in either claim 1 or claim 2, wherein the high density polyethylene foam is of thickness in the region of 3 mm. 4. A method as claimed in any one of the preceding claims, wherein the low density foam is of a thickness between 5 and 15 mm. 5. A method as claimed in any one of the preceding claims, wherein the laminate is moulded to shape at a temperature in the region of 90°C. 6. A method as claimed in any one of claims 1 to 4, wherein a layer of polycarbonate resin is provided and placed on said sheet of high impact strength polymer either before or immediately after the piece or pieces of high denεity polyethylene foam are placed thereon. 7. A method aε claimed in claim 6, wherein the layer of polycarbonate resin has a thickness in the region of 3mm. 8. A method as claimed in either claim 6 or claim 7, wherein the laminate iε moulded to εhape at a temperature in the region of 150°C. 9. A method aε claimed in any one of the preceding claims, further compriεing placing a layer of open cell polyurethane foam at such a stage that it lies between the sheet of high impact strength polymer and the layer of low density foamed plastics material. 10. A method as claimed in any one of the preceding claims, further compriεing placing a layer of cloεed cell foam into the laminate, whereby the produced article haε buoyancy propertieε. 11. A method aε claimed in any one of the preceding claims, wherein one or more strapε are attached during the method and are located between the high denεity polyethylene foam layer and the low density foamed plasticε material layer. 12. A method of making a semi-rigid protective material for use on a body subεtantially as described herein with reference to the accompanying drawings. 13. A protective material made by a method as claimed in any one of the preceding claims.

Inventors: BELL KEITH MICHAEL, STANESBY GERALD REGINALD, BELL, KEITH, MICHAEL, STANESBY, GERALD, REGINALD
Applicants: SPORTS PRETECTION LTD, SPORTS PROTECTION LIMITED
Application year: 1989
Main classification: A41D31
IPC codes: A41D31, A63B71