The present invention relates to papermachine clothing and particularly but not exclusively to shoe press belts.

One form of papermachine clothing comprises a woven or non woven base cloth to which a coating of polymer is applied. In one method of manufacture an endless base cloth is fed around a series of rollers and around a part of a horizontally mounted rotatable drum. As the belt passes around the drum heat-softened polymer is applied into the nip between the belt and the drum.

In this process there is a tendency for the heat softened polymer to slump as it approaches the base of the drum. This is undesirable in that the polymeric layer applied to the belt is of non uniform thickness.

The present invention has been made from a consideration of this problem.

According to a first aspect of the present invention there is provided a method of making papermachine clothing comprising the step of feeding a base cloth over a rotating body and applying a polymer coating to the base cloth as the base cloth is fed over the rotating body, wherein the polymer coating is impregnated with a thixotrope. The thixotrope acts to increase the viscosity of the "fluid" polymer once applied to the base cloth.

Surprisingly the toughness, modulus and abrasion resistance of the papermachine clothing is significantly improved by incorporation of the thixotrope into the polymer coating.

According to a second aspect of the present invention there is provided papeptiachine clothing comprising a base cloth having a coating of polymer thereon, wherein the polymer is impregnated with a thixotrope.

Aramid fibres such as KEVLAR (RTM) (para-phenylene terephthalamide) are preferred. The fibres are preferably-chopped into lengths in the range from 0.8mm to 4.00mm and preferably have a diameter in the order of 12uιι. KEVLAR (RTM) is particularly preferred in that the random orientation and physical entanglement of the fibres and fibrils thereof align in the direction of applied shear thus increasing the viscosity of the polymer. Alternatively fused silica may be used as a thixotrope.

The polymer is preferably thermoset. Polyurethane is preferred.

In order that the present invention may be more readily understood a specific embodiment thereof will now be described by way of example only with reference to the single accompanying drawing which shows one apparatus for making papermachine clothing in accordance with the present invention.

Referring to the drawing an apparatus 10 for

making papermachine clothing such as a shoe press belt comprises a horizontally mounted rotatable drum 11 and a plurality of rollers 12 which define a path over which an endless base cloth 13 travels. A series of infra-red heaters 14 are provided adjacent the drum 11 on the side of the base cloth 13 which is remote from the drum 11. A polyurethane coating may be applied to the base cloth 13 by utilising a feed nozzle to project the heat softened polymer into the nip 15 between the base cloth 13 and the top of the drum 11. The polyurethane coating is impregnated with chopped aramid fibres in order to prevent sagging of the polymer on the drum and to improve the abrasion resistance of the belt.

In order to impregnate the polyurethane coating with the chopped aramid fibres the fibres are added in substantially equal amounts to the thermoset precursor material. The aramid containing precursors (e.g. polyol and isocyanate) are mixed immediately prior to applying the impregnated coating to the base cloth. The amount of aramid fibre added is preferably less than 3% by weight.

The strength of a prior art polyurethane coated belt "A" was tested. Similarly the strength of a belt incorporating 0.17% KEVLAR (RTM) was tested. The results are set out below.

Average Strength (Kg/2.5cm)

"A* Polyurethane (Prior Art) 91.3 ^• B' Polyurethane 94.5

+ 0.17% Kevlar

It can be seen that the incorporation of very small amounts of KEVLAR fibres significantly increases the strength of the press belt.

It is to be understood that the above described embodiment is by way of illustration only. Many modifications and variations are possible.