NZ196651A - Leg guard production and product thereof - Google Patents

Description

1 96 6 Priority Dsts(s): . Ift.'fb.'&t, Complete Specification Filed: Ciass: PubKcation Date: .... 1 .M.au&wbJ P.O. Journal No: ... 1^1 NEW ZEALAND Patents Act, 1953 COMPLETE SPECIFICATION "IMPROVEMENTS IN OR RELATING TO LEG GUARDS . " We, STAFFORD RUBBER COMPANY LIMITED, a British company of Ringway Industrial Estate, Eastern Avenue, Lichfield, Staffordshire WS137SF ENGLAND do hereby declare the invention, for which we pray that a Patent may be granted to us , and the method by which it is to be performed, to be particularly described in and by the follbwing statement (Followed by 1A.) 1 966 5 1 IMPROVEMENTS IN OR RELATING TO LEG GUARDS This invention relates to leg guards, in particular to leg guards for protecting the ankles, shins, knees or other parts of the legs of games players. The invention is concerned particularly with cricket pads, and it is with reference to cricket pads that the following description particularly relates.

The conventional form of cricket pad provides adequate protection for the players but is of a structure whose production is labour-intensive and therefore expensive. 10 There is, in consequence, a demand for a pad that can be produced simply and cheaply and yet provide satisfactory protection for the player.

Various proposals have been made to manufacture cricket pads from plastics materials but none of these have gone very far in challenging the superiority of the conventional pad, despite the expense of the latter. One of the principal disadvantages of the pads of plastics materials hitherto proposed is that, where they have been of sufficient strength to withstand continual impact with the ball, they have not v been sufficiently flexible to permit the user easily to bend his leg, and therefore they have not been comfortable to wear0 1966 5 1 The present invention nov; provides a cricket pad or other leg guard which is of sufficient robustness and yet which is flexible enough to permit the user easily to bend, his knee and therefore to wear the guard with comfort.

Accordingly, in one aspect the invention provides a cricket pad or other leg guard formed from plastics material, comprising a first, outer layer which provides an impact-resistant surface; and a second, inner layer which provides a resilient padding for the leg of a user of the guard.

In a second aspect, the invention provides a cricket pad or other leg guard, which comprises a lower portion to protect, in use, at least the shin of the user; and an upper portion to protect, in use, at least the lower part of the thigh of the user; and the lower and upper portions are disposed with reference to. the overall dimensions of the leg guard so that, in use, the knee of the user is behind a knee zone connecting, or comprising contiguous border zones of, said lower and upper portions, the leg guard having flexibility in said knee zone to permit hinge-like movement of said lower and upper portions. n In the preferred embodiments of the invention the inner \ layer serves the dual purpose of absorbing energy from the ball when it strikes the pad and also of providing a comfortable surface to bear against the leg of the user. 1 96 6 5 1 Flexibility of the pad in the region adjoining the upper and lower portions can be provided, for example, by the use of slots or other re-entrant means extending inwardly from the side edges of the pad. Another means is to have a reduced thickness of pad (for example by having a reduced thickness of the inner layer) in the knee zone of the pad. A further means of providing enhanced flexibility, which can be used with either or both of the features referred to above, is the use of relief lines or other relief zones extending across the pad in the knee zone (for example. between the inner ends of opposed re-entrant means referred to above). These zones (which can, for example, be grooves or other areas of reduced thickness in the outer surface of the pad) can, if deep enough, facilitate bending of the pad in the knee zone.

The inner and outer layers can be layers of a laminate of plastics material providing, on one face thereof, an impact or wear-resistant surface and on the other face a resilient comfortable material for the leg of the user.

These laminates can be of two, three or more layers. In a preferred form of the invention the outer or outermost layer consists of a wear-resistant flexible thermoplastic material. 1 96 6 5 1 This material is conveniently a polymer of an alpha-olefin, for example a polyethylene or a polypropylene. The material comprising the inner or innermost layer of the pad is conveniently a cellular or foam plastics material; and in one form of the invention this plastics material is a polymer of an alpha-olefin, for example a polyethylene or a polypropylene. In between these two layers, if desired, there can be a further layer or layers, for example a layer of a cellular or foam plastics material (for example of a poljrethylenejpolypropylene or other polyolefin) securely bonded to each of the other two layers or to the adjacent layers, as the case may be. In a preferred form of the invention this intermediate layer is of a polymer having the same chemical constitution as that of the inner layer.

In a preferred form of cricket pad according to the present invention the thickness of the outer layer, any intermediate layer and inner layer are of progressively increasing amounts. For example,where the laminate or other multi-ply material consists of two layers, the ratio of thickness of the outer and inner layers is conveniently in the range 1:12 to 1:8, for example 1:11 to 1:9; and where the laminate has three layers, the ratio of the thickness of the inner lavef to the total thickness of the outer and intermediate layers is preferably in the range 3:1 to 3:2, for example 2:1 to 3:2, and the intermediate layer is preferably of greater thickness than the outer layer, a suitable ratio being in the range 10:1 to 2:1, for example 6:1 to 3:1.

There is nov; described, by way of example and with reference to the accompanying drawings, a cricket pad according to one embodiment of the present invention.

In the drawings: Figure 1 is a front elevation of the pad shown, for the sake of convenience, in a flat configuration prior to being shaped into a leg-embracing configuration; and Figure 2 is a perspective view of the pad in its leg-embracing configuration.

The pad comprises a laminate of first (outer) and second (inner) layers 10, 11 of thermoplastics material. The pad further comprises lower portion 10a, 11a and upper portion 10b, lib. The lower portion, in use, protects the shin and ankle of the user and the upper portion protects the lower part of his thigh. The outer layer 10, that is the layer facing outermost when the pad is in its leg-embracing configuration, comprises an elongate sheet of polyethylene having an overall shape which is generally rectangular and having two opposed side edges 12, 13, a top edge 14 and a bottom edge 15. The bottom edge has formed therein a centrally disposed recess 16 to receive the upper part of the foot of the user whereby the two adjacent salient 1 % 6 5 portions 17, 18 can provide protection for his ankle bones. In the side edges 12, 13 thnre are two symmetrically disposed re-entrant slots 19,20 having enlargements 21, 22 at their inner ends. outer The Aayer 10 is of non-cellular polyethylene having a thickness of 1.5 mm, and the inner layer is of cellular or foam polyethylene having a thickness of 15 mm. The laminate providing layers 10 and 11 is one made by a process of flame bonding.

The polyethylene used for the outer layer conveniently has a specific gravity in the range 0.91 to 0.99, Examples of suitable polyethylenes are the low density polyethj'-lene sold under the Trade Mark Lintacell (specific gravity 0.93) and the high density polyethylenes sold under the Trade Mark Prelen (specific gravity 0.96) and Hilex sold by British Celenese Limited (specific gravity 0.96 ).

The cellular polyethylene used for the inner layer conveniently is one having a closed cell structure. It can *2 have, for example, a density in the range 30 to 60 kg/m . Examples of suitable cellular polyethylenes are Frelen 30/06 (density 30 kg/m^), Prelen 50/06 (density 50 kg/m^), Lintacell 30/06 (density 30_kg/m^) and Alveolit of the 2000 •z range, for example 2015 (density 50 kg/m \ 1 966 5 1 A summary of the mechanical and physical properties of Alveolit 2000 is given below.

DIN Standard Unit Apparent density Tensile strength lengthwise crosswise (Specimen thickness 3mm) Elongation lengthwise crosswise (Specimen thickness 3 mm) Tear resistance lengthwise crosswise (Specimen thickness 3mm) Compressive strength 20$ deflection 50$ deflection Thermal conductivity at 0°C Working temperature range Water vapour transmission (Thickness 2mm) 53 420 53 571 53 571 53 575 53 577 kg/m-5 kp/c m kp/cm kp/cm' 50 ,6 4,0 280 210 2,8 1,8 0,45 1.2 53 122 kcal/m.h/b 0,037 °C -80 up to + 80 g/m2.24h 1,2 1 s f o 5 A summary of the mechanical and physical properties of Hilex is as follows.

Test Density - Tensile yield stress ISO R 527 Tensile modulus BS 4618 Izod notched impact strength BS 2782 Melt index BS 3412 Unit g/cm kg/cm kg/cm J/m g/10 mins. 0.96 310 11,200 480 0.6 Another suitable polyethylene for the outer layer is that sold under the trade mark RIG-IDEX "by B.P. Chemicals Limited. 1 966 5 1 The shape and dimensions of the inner and outer layers is the same in the embodiment shovm in the drawings.

The location of the re-entrant slots 19,20 in relation to the length of the guard is such that,when the pad is fitted to a leg of the user, his knee is in the region of the zone 23 between the two slots. It is, therefore, necessary that the pad should bend in that region, and this bending is facilitated by the re-entrant slots. Bending of the pad is further facilitated by arranging that the curvature of the upper portion of the pad is less than that of the lov/er portion, thereby permitting the side edges of the upper portion to pass outside the side edges of the lower portion when the user bends his knee. Moreover, the upper pad portion is disposed at an angle to the lov/er pad portion so that, after thermo forming, the border zones 24, 25 of the upper portion overlie the corresponding border zones 26, 27 of the lower portions. The purpose of this is to ensure that when the knee of the user is bended the upper portion passes over the lower portion v/ithout the edges fouling each other.

The contiguous border zones of the lower and upper pad portions have formed therein aligned, spaced apart slots 28, 29 and 30, 31 disposed on opposite sides of the re-entrant slots 19,20. These slots accommodate, edge protectors 32, 33, 34, 35 disposed so that adjacent pairs contact each other and prevent wear of the border zones containing them„ 1 966 5 1 The drawings show a single pad suited for a user's right leg. A pair of pads can, for example, comprise two identical pads as shown, for instance,in Figures 1 and-2, or a pair can consist of two like, though not identical, pads having such differences as may "be necessary or desirable to suit right and le"t legs.

The pad of the drawings has a series of slots 36, 36a in the respective side margins of the pad to receive straps for securing the pad on the user's leg; and two of the straps 37, 38 are shown, strap 37 being a buckle strap and strap 38 a tongue strap for engagement with buckle strap 37. Figures 1 and 2 are to be regarded as having a buckle strap attached to each of slots 36 and a tongue strap in each of slots 36a.

The straps shown in the drawings are of a novel construction in that, instead of being adapted for attachment to the pad by stitching or by riveting, they are provided with press-studs and associated stud-receiving recesses by means of which they can be fixed in place.

The pad has formed in the surface of outer layer 10 shallow grooves 39 "to simulate the stitching of a conventional canvas pad. t 966 5 1 The pad can be provided with slits or other ventilation means (not shown), preferably passing through both the inner and outer sheets, to enhance the comfort of the user, especially in hot climates.

The cricket pad described above with reference to the drawings can be made by the following method. From a sheet of a flame-bonded laminate of the non-cellular and cellular polyethylene there is cut a pad, the cutting operation . providing at the same time the slots 28, 29, 30, 31, strap- "A receiving slots 36, 36a and stitching simulating grooves 39. The resulting planar pad is subjected to a thermo-forming process to give it the desired degrees of curvature to provide the leg-embracing shape required of the pad, the radius of curvature of the upper portion of the pad being greater, preferably, than that of the lower portion for the reason given above. The edge protectors 32, 33, 34, 35 and straps 38, 39 can then be fitted in the respective slots to complete the pad.

The pad described above v/ith reference to the drawings has substantial advantages over a conventional canvas pad. a First, it is/weight of about half that of a conventional pad of senior grade. Secondly, it transmits through the pad a much smaller proportion of the force of a cricket ball striking its outer surface.

The following results (expressed in kilo-newtons)° have been obtained using the procedure described in the Second t 96 6 5 Draft of British Standard Leg Guard dated June 1980.

Part of pad struck Pad of the Conventional "by the ball Invention Canvas pad Instep 0.5 - 0.8 1.7 - 1.9 Shin 0.5 - 0.8 1.3 - 1.4 Knee 0.5 - 0.8 1.0 - 1.2 19665!

Claims (13)

WHAT WE CLAIM IS:-

1. A method of producing a leg guard which comprises forming a laminate comprising at least a first,impact-resistant layer of a non-cellular plastics material and a second resilient layer of a plastics material, parting from the laminate a flat blank and shaping the blank to the desired shape of the guard, said first layer providing an impact-resistant, outer layer of the guard and said second layer providing a resilient padding for the leg of the user of the guard.

2. A method according to claim 1 in which the guard is a cricket pad.

3. A method according to claim 1 or 2 in which the said laminate consists of said first and second layers.

4. A method according to claim 1, 2 or 3 in which said first layer is of a non-cellular polyethylene or polypropylene.

5. A method according to claim 4 in which the first layer is of polyethylene having a specific gravity in the range from 0.91 to 0.99.

6. A method according to any of the preceding claims in which the said second layer is of a cellular polyethylene or polypropylene.

7. A method according to claim 6 in which said second layer is of polyethylene having a density in the range from 30 to 60 kg/m^.

8. A method according to any one of the preceding claims in which the ratio of the thickness of said first and second layers is in the range from 1:12 to 1:8. 13 19 AUG 1983 196651

9. A method according to any/(of the preceding claims in which said shaping of the blank is effected under the influence of heat and moulding.

10. A method according to claim 1 or 2 in which the laminate is formed by flame-bonding together the first and second layers; the first layer is of non-cellular polyethylene haying a specific gravity in the range from 0.9 2. to 0.99; the second layer is of closed-cell cellular polyethylene having a density 3 in the range from 30 to 60 kg/m ; and the ratio of the thickness of the first layer to that of the second layer after said bonding is in the range from 1:9 to 1:11.

11. A method according to claim 1 substantially as described herein with reference to the accompanying drawings.

12. A leg guard obtained as the product of the method of any one of the preceding claims.

13. A cricket pad obtained as the product of the method according to claim 1 substantially as described herein and substantially as in the accompanying drawings. STAFFORD RUBBER COMPANY LIMITED By Their Attorneys HENRY HUGHES LIMITED - 14 - PJ.Z. PATENT OFFICE 19 AUG 1983