This invention concerns methods and materials for the production of polymeric compositions, particularly, though by no means exclusively, suitable for use in the formation of impact absorbing surfaces or substrates to sports or play areas.

Known such impact absorbing surfaces comprise crumbs of a natural or synthetic rubber, such as EPDM for ex»ample, in a matrix of polymer, such as polyurethane for example.

The matrix may completely fill the spaces between the crumbs to give a non-porous composition or may simply coat the surfaces of the crumbs to cause them to adhere leaving the interstices between the crumbs void to give a porous product.

Either kind of composition may be laid to form a sports or play surface or to form a -substrate to another surface such as that provided by synthetic turf for example, or a composite surface may be formed by a base layer of porous material topped by a non-porous layer.

The compositions are prepared on site immediately before use by mixing crumb, liquid polymer and if

necessary a catalyst, to enable them to be laid, in the manner of asphalt, before polymerization has advanced sufficiently to render them unworkable. Advantageously polymerization times are short to reduce the risk of damage to the finished surface before it has set.

The on site preparation and short setting time neccessitates expensive equipment and highly trained operators regardless of the size of the project.

It is an object of the present invention to provide a method and materials for production of a porous composite which overcomes the disadvantage aforesaid.

According to the present invention there is provided a method of producing a porous composite comprising the steps of :-

forming a shaped mass of particulate material whose surfaces have been pre-wetted with a liquid polymer which will not readily polymerise by the action of air or water vapour; and

treating the particle/polymer mix with a liquid curing agent medium to initiate polymerization of the liquid polymer, either immediately before or after formation of said mass.

The shaped mass may be a horizontal layer.

The liquid polymer may include an inhibitor or retarder to give extended shelf life.

The liquid medium may contain a catalyst or a chemical to neutralise any inhibitor or retarder present in the liquid polymer.

Both the rubber particle/polymer mix and the liquid medium may be prepared at a central facility and transported to application sites as required. The particle/polymer mix will without curing agent have a sufficiently long polymerization time to enable such transport and laying by relatively unskilled labour.

The particulate material may be a natural or synthetic rubber crumb.

The particle/polymer mix may be immersed in the liquid medium for a predetermined short period before formation of the shaped mass.

The liquid medium may be applied to the laid crumb surface by spraying or pouring.

The invention also includes compositions for use in practising the methods aforesaid.

The invention will be further apparent from the following description, which concerns, by way of example only, the laying of a running-track in accordance with one method thereof.

Onto a suitable sub-base a base coat comprising a mix of rubber crumb wetted with a suitable resin which does not readily polymerise by the action of air or water vapour is laid using conventional concrete or asphalt laying techniques and equipment.

A liquid medium is then sprayed over the crumb surface so as to pass through the interstices of the mix and effect rapid polymerization of the resin to join the crumbs into a coherent mass. Excess liquid disperses into the sub-base.

Both the crumb mixture and liquid medium can be prepared off-site and safely stored for a period before being transported for use.

The resin may consist of a liquid glycidyl ether resin such as a polyglycidylether prepared by the reaction of bisphenol with epichlorohydrin, available from Shell Chemicals under the Trade name EPIKOTE.

Such resins may be cured with a polyamine such as a phenol-amine-formaldehyde condensation product for

example those available from Shell Chemicals under the Trade name EPIKURE, or a polyaminoamide such as Casamid.

Examples of preferred formulations will now be given,

Example I

Base Coat w/w

EPIKOTE 828 8.5

Rubber Crumb 86.0

Liquid Medium Curing Agent

EPIKURE DX 138 5.15

Ancamine 0.15

Example II

Base Coat w/w

EPIKOTE 255 9.2

Rubber Crumb 86.0

Liguid Medium Curing Agent

Casamid 360 9.2

Antifoam 0.4

Water 1.2

Propyl alcohol 2.3

In an alternative approach the crumb/polymer mix is immersed in the liquid medium curing agent for a predetermined short time to initiate polymerisation before the mix is laid. Typically a soak time of around 30 minutes might be used leaving a mixture with a working life of around 3-4 hours, but this can be adjusted by varying the formulations and/or the soak time.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible, without departing from the scope thereof as defined by the appended claims.

Thus, for example, the particulate material may comprise cork crumb, gravel, chipped bark or any other material suited to the intended application.

Again, for example, the composition may include fillers, colouring materials or other known additives.