WO2006056764A1

WO2006056764A1 - Synthetic recreational surface

Info

Publication number: WO2006056764A1
Application number: PCT/GB2005/004492
Authority: WO
Inventors: Frank Bowers; Jacqueline Mary Bowers
Original assignee: Frank Bowers; Jacqueline Mary Bowers
Priority date: 2004-11-25
Filing date: 2005-11-23
Publication date: 2006-06-01
Also published as: GB2434991A; GB0425903D0; GB2434991B; GB0708051D0

Abstract

A method of forming a free draining impact absorbing recreational surface with natural foot-feel that protects sportpeople from injury due to falling and training comprises the steps of mixing rubber granules with a liquid polymer, laying the mixture onto a prepared sub-base before polymerization of said polymer is complete so as to form a compliant mass having substantial voidage therein, and allowing said polymer to polymerise. The substantial voidage is filled with a particulate material. The compliant mass may also be covered with a particulate material.

Description

SYNTHETICRECREATIONALSURFACE

This invention relates to methods and materials for the production of

impact absorbing synthetic recreational surfaces, particularly, though

by no means exclusively, for rugby, soccer, and as a horse racing

track.

An ideal recreational surface will absorb the relatively high energy

impacts associated with falling sportspeople and repeated low energy

impacts associated with heel impacts during training. The surface will

allow controlled sliding of an impacted foot during sudden stopping

and turning thus preventing excessive stress on the sportsperson's

muscular-skeleton system. The surface will also exhibit a natural foot-

feel response similar to natural turf in a dry but yielding condition.

Importantly, the ideal surface will be free draining and will not water¬

log during prolonged heavy rain conditions.

Known impact absorbing surfaces comprise of granules of a natural or

synthetic rubber, such as EPDM for example, in a matrix of polymer,

such as polyurethane for example. The granules are usually sized from lmm to 5mm. These surfaces are laid onto a prepared substrate of

crushed stone or asphalt. Such surfaces have serious disadvantages

if used as a sporting surface. If the surface has a natural foot-feel

response, it requires a surface that is too thin or too stiff to absorb

the energy associated with falling sportspeople. Moreover, prolonged

use on such a surface will result in stress-related injuries, viz shin

splints etc. On the other hand, if the surface is thick and/or resilient

enough to absorb the low and high energy impacts associated with

sporting activity, the foot-feel will be too 'bouncy' and will inhibit

sporting activity. The coefficient of friction of the surface for normal

sporting footwear is extremely high. Sudden stopping or pivot turning

will cause considerable stress on the sportsperson's muscular-skeleton

system - particularly knees, ankles and shins.

The present invention seeks to obviate the above and other

disadvantages of known impact absorbing surfaces by providing

an improved impact absorbing surface having varying characteristics

suitable for particular sporting applications. According to one aspect of the present invention there is provided a

method of forming a free draining impact absorbing recreational

surface with natural foot-feel that protects sportspeople from injury

due to falling and training comprising the steps of mixing rubber

granules with a liquid polymer, laying the mixture onto a prepared

sub-base before polymerization of said polymer is complete so as to

form a compliant mass having substantial voidage therein, and

allowing said polymer to polymerise.

Preferably, the method will include the further step of filling said

substantial voidage with a particulate material

The method will preferably include the still further step of covering

the filled rubber/polymer matrix with a particulate material to affect

controlled foot slippage.

Preferably, the liquid polymer will be polyurethane or epoxy based,

and the rubber granules will preferably be natural or synthetic rubber. According to another aspect of the present invention there is

provided a free draining impact absorbing recreational surface with

natural foot-feel that protects sportpeople from injury due to falling

and training comprising a compliant mass having substantial voidage

therein, said compliant mass consisting of rubber granules bound

together with a polymer.

Preferably, said substantial voidage will be filled with particulate

material, and said compliant mass will preferably be covered with

particulate material to affect controlled foot slippage.

Preferably, the compliant mass comprises a mixture of rubber

granules and liquid polymer, the liquid polymer preferably being

polyurethane or epoxy based

The particulate material will preferably be river washed sand, clay

court tennis top dressing, small rubber granules or any suitable

mixture or other material suited to the intended application. In general terms of the present invention, the compliant mass or

shockpad comprises of granules of a natural or synthetic rubber

such as SBR and/or EPDM for example, in a mixture of polymer. The

granules may be sized from 2mm to 15mm. The shockpad may have a

thickness from 10mm to 50mm. The interstice between the granules in

the body of the shockpad is filled with a particulate material of an

essentially round profile which ensures that the particles do not

consolidate to form a non-permeable membrane, thus ensuring long-

term hydraulic conductivity. The particulate material also

mechanically dampens the response to deformation and restoration

due to impacting forces, thus absorbing both high and low energy

impacts without creating an unnatural foot bounce. The playing

surface is formed by broadcasting a specified amount of particulate

material onto the upper surface of the shockpad to ensure optimum

slippage for a specific sport and associated footwear. The thickness

and composition of this top dressing will depend on the specific

sporting application and may be from 0mm to 15mm thick. The

particle size of the top dressing may be from 0mm to 2mm. The invention will be further apparent from the following description,

which concerns by way of example only, the preparation of one form

of recreational surface embodying same, and with reference to the

accompanying drawing, the single figure of which is a cross-section

therethrough.

An area of land is treated to destroy any plant seeds therein and

covered with a layer of graded crushed stone 1 which may incorporate

land drains if required.

A shockpad comprising of rubber granules bonded together by

polyurethane 2 is laid on top of the crushed stone 1 to a depth of

35mm. The shockpad is formed by mixing the rubber granules with a

liquid polymer and laying it before polymerization is complete, to

form a coherent but compliant mass having substantial voidage

therein. The granules may be SBR derived from vehicle tyres and

may have sizes in the range from 6mm to 10mm. The liquid polymer

may be moisture-curing polyuretrhane based pre-polymer at a concentration of 18% by weight. After approximately eight hours the

moisture-curing polyurethane polymerises and an impact absorbing

water permeable shockpad is formed.

Slurry comprising of water and river-washed sand is dispersed over

the upper surface of the shockpad 2. The slurry is 'worked' with a

suitable tool to force it through the interstice of rubber granules/

polyurethane matrix. After a few hours the water drains from the

slurry leaving the voidage in the shockpad filled with the river- washed

sand and a mechanically damped impact absorbing water permeable

shockpad is so formed.

Tennis court red clay top dressing is broadcast over the upper surface

of the shockpad 2 and raked to a depth of 2mm. The playing surface 3

may be watered from time to time to facilitate ideal foot traction and

foot slippage.

After each playing session, the playing surface may be raked to ensure an even covering of the shockpad 2.

It will be understood that the playing surface will drain even during

heavy rainfall. Moreover, the surface will protect the sportspeople

from high and low energy impacts whilst providing ideal foot traction

and feel.

It will be appreciated that it is not intended to limit the invention to

the above example. Many variations, such as might readily occur to

one skilled in the art, are possible, without departing from the scope

of the invention as defined by the appended claims.

Whilst the specific example is concerned with incorporating SBR into

the shockpad, it will be understood that other rubbers, both natural

and synthetic, might be used. Moreover, small rounded stone might be

mixed with the rubber granules to modify the mechanical properties of

the shockpad. Whilst the specific example incorporated tennis court red clay top

dressing as the playing surface, many other types of particulate

materials might be employed as a top dressing, for example small

rubber granules, sharp or round sand, or any material suited to the

intended application. These particulate materials might also be used

to fill the interstice of the shockpad.

Whilst the specific example employed slurry to fill the interstices of

the shockpad, other methods may be employed, such as broadcasting

dry powder over the upper surface and brushing the powder and

vibrating the surface to affect penetration into the interstices.

Yet again, for example, the shockpad may be laid onto a sub-base

of porous asphalt or any other suitable water permeable sub-base.

Yet again, for example, the resin system used in the shockpad may be

an epoxy resin system or any polymer system suited to the intended

application.

Claims

CLAIMS:

1. A method of forming a free draining impact absorbing

recreational surface with natural foot-feel that protects sportpeople

from injury due to falling and training comprises the steps of mixing

rubber granules with a liquid polymer, laying the mixture onto a

prepared sub-base before polymerization of said polymer is complete

so as to form a compliant mass having substantial voidage therein,

and allowing said polymer to polymerise.

2. A method according to Claim 1, including the further step of

filling said substantial voidage with a particulate material.

3. A method according to Claim 1 or Claim 2, including the still

further step of covering the filled rubber/polymer matrix with a

particulate material to affect controlled foot slippage.

4. A method according to any of Claims 1 to 3, wherein the polymer is polyurethane or epoxy based, and the rubber granules are

of natural or synthetic rubber.

5. A method according to any of Claims 2 to 5, wherein said

particulate material is tennis court red clay top dressing, sand, small

rubber granules, or other suitable material.

6. A free draining impact absorbing recreational surface with

natural foot-feel that protects sportpeople from injury due to falling

and training comprises a pliant mass having substantial voidage

therein, said compliant mass consisting of rubber granules bound

together with a polymer.

7. A recreational surface according to Claim 6, wherein said

substantial voidage is filled with a particulate material.

8. A recreational surface according to Claim 6 or Claim 7, wherein

said compliant mass is covered with particulate material to affect controlled foot slippage.

9. A recreational surface according to any of Claims 6 to 8,

wherein said liquid polymer is polyurethane or epoxy based.

10. A recreational surface according to any of Claims 7 to 9,

wherein said particulate material is river washed sand, clay court

tennis top dressing, small rubber granules or other suitable material.

11. A recreational surface according to any of Claims 6 to 10,

wherein said compliant mass is water permeable.