Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1996-07-25
1998-12-15
Raimund, Christopher
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
428196, 442 76, 442148, 427244, 427288, B32B 2714
Patent
active
058493956
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to industrial fabrics such as papermachine clothing or like fabrics.
When in use industrial fabrics suffer from the problems of fibre shedding and wear. The present invention seeks to address these problems.
One known method of surface modification for industrial fabrics such as corrugator belts comprise the lick-roll application of water-based acrylic polymer. This process is not particularly reliable.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a method of making an industrial fabric including the steps of providing a textile substrate, providing a film forming polymer affixed to a release sheet, applying said polymer to a surface of the base cloth, curing the polymer and removing the release sheet so as to provide an industrial fabric having a textile substrate, at least one surface of which is coated with the film forming polymer wherein the polymer coating is reticular. The coatings of the invention may involve impregnating the base cloth. Examples of suitable film forming polymers include epoxy resins, plastisols (i.e. a polymer dissolved in the bare minimum of solvent) or aqueous polyurethane systems.
The fabrics of the present invention have particular application as press felts. The fabrics may also be used in corrugator belts in which the polymer coating is applied at the edge regions of the fabric to increase the abrasion resistance of these areas. The fabrics are also suitable as filter cloths where the improved smoothness of the fabric surface resulting from the coating gives improved cake release.
The polymer film provides a harder more wear resistant surface having improved abrasion resistance. It also prevents fibre shedding. A further advantage, when used as a coating for papermakers fabrics, is that the improved surface smoothness reduces the start-up time required on the paper machine. Normally a fabric has initially to be run on a machine for a certain amount of time to smoothen the surface before it can be put into action.
The reticular polymer coatings referred to herein are coatings comprising a network of two dimensional pores thus providing permeability.
According to a second aspect of the present invention there is provided an industrial fabric comprising a textile substrate, wherein at least one surface of the textile substrate is coated with and/or is impregnated by a film forming polymer, the polymer coating being reticular.
The use of the release paper method of resin application enables the fabric heat-setting step to be combined with the resin treatment if desired, and whereas conventional coating processes utilise aqueous resin emulsion systems which require a large energy input to remove water, the method according to the invention consumes only a small amount of energy. The reticulated resin coating ensures that fibre shedding is reduced due to a more effective bedding down of protruding surface fibres. This method is also advantageous in that the absence of waste effluent or solvents means that the process is more ecologically acceptable. Further refinements include the utilisation of a more uniform of lower denier fibre batt surface. The greater fibre density at the surface, controlled by known methods such as choice of batt fibre denier and/or needling technique, enables a more uniform resin application to be achieved, thereby reducing brittleness by reducing the opportunity for resin-rich areas to form. Toughness can be improved by increasing cure time at the expense of cure temperature.
The release sheet may typically comprise silicone release paper, aluminium foil or polyethylene or PTFE-coated non-woven fabrics. The polymer would be in the form of a film.
The textile substrate may be fed over at least one roller. The release sheet would be fed into the nip between the textile and one of the rollers. The paper is held under tension to prevent creasing. The angle of application of the release sheet to the substrate/roller is preferably in the range from 3
REFERENCES:
patent: 4689258 (1987-08-01), Slosberg et al.
patent: 4772504 (1988-09-01), Andresen
Sayers Ian C.
Valentine Craig
Raimund Christopher
Scapa Group PLC
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