Joining tape

Abstract

Tape or patch material for making joints which have good tensile strength includes a reinforcing array of yarns arranged within a narrow range of angles around the direction of application of probable stress on the joint. The distribution of yarns angles within a small range rather than exactly parallel to each other gives the joint greater splitting resistance with very little loss in strength, and it permits toleration of less precise alignment of tape when the joint is made. The patch material is particularly useful for joining coated abrasives into endless belts. For such joints, it has long been known that better results are achieved if the joint makes an angle other than perpendicular with the edges of the belt. Patch material particularly convenient for making such angled joints can be made by laying out the reinforcing yarns between two parallel carrier strips, with the yarns symmetrically disposed around a smaller angle with the strips which is the same as the smaller angle which the desired joint will make with the edges of the belt, then encapsulating the array of yarns in adhesive and processing the adhesive to give it cohesion. The adhesive-encapsulated, yarn-containing web can then be slit on a conventional straight slitter to the proper width for reinforcing the joints to be formed. Lengths of the web thus slit, when applied to the angled joints to be formed, will have their reinforcing yarns symmetrically disposed around the running direction of the belts made. For best results, the yarn array should be compressed after encapsulating it with adhesive, so that the final patch material has at least as high a volume of yarn as of adhesive.