Method of coating nylon and polyester fibers with water dispersible polyvinyl acetate and coating achieved therefrom

Abstract

An aqueous, coatable, thermally condensable composition is disclosed. The coating is based on dispersions of vinyl acetate polymers in water. Uniquely, the coating can be advantageously used for both nylon and polyester yarns. The coated yarns exhibit performance equivalent to or better than coated yarns based on traditional compositions.

Description

FIELD OF THE INVENTIONThis invention relates to an aqueous coating process for use with synthetic fibers. In particular, this invention relates to a coating process that can be effectively employed with both solution dyed nylon yarn and non-solution dyed nylon yarn as well as with polyester yarns. Specifically, this invention relates to a water dispersible coating based upon polyvinyl acetate.BACKGROUND OF THE INVENTIONNylon and polyester yarns, regardless of the number of plies, are generally not suitable for use in industrial sewing applications unless they are bonded with a polymeric coating that encircles, or encapsulates, the yarn. The coating protects the twisted yarn from breaking and unraveling into the individual cords. An uncoated yarn used in industrial sewing applications will experience fraying and a significant number of breaks due to the high line speeds, significant tension, and significant friction.Coating compositions, or bonding agents, that are employed with nylo...

AI Technical Summary

Benefits of technology

The present invention meets these and other needs by providing an aqueous coating system in which polyvinyl acetate homopolymers and copolymers are used as the bonding agent. More than one polyvinylacetate may be utilized to achieve the coating. The polyvinyl acetate system is effective for the coating of both types of nylon yarns as well as for polyester yarns.

The need to employ a separate scouring operation for the various yarns is minimized with the polyvinyl acetate and water system. The need for the separate scouring operation is further reduced by the inclusion of a coupling agent in the polyvinyl acetate / water coating emulsion.

Problems solved by technology

Nylon and polyester yarns, regardless of the number of plies, are generally not suitable for use in industrial sewing applications unless they are bonded with a polymeric coating that encircles, or encapsulates, the yarn.

An uncoated yarn used in industrial sewing applications will experience fraying and a significant number of breaks due to the high line speeds, significant tension, and significant friction.

Such systems pose fire, health, and environmental hazards and are expensive.

These organic solvents are also prone to cause leaching of dye from the yarns.

Additionally, the use of such systems may in the future become limited due to governmental regulations.

Between methanol and methylene chloride, the concomitant hazards associated with the use of methylene chloride are appreciably more severe than those associated with the use of methanol.

Unfortunately, the use of methanol systems to coat polyester yarns with common coatings, such as the aforementioned low molecular weigh nylons, has not proved to be as efficacious.

Another problem with prior art processes used for the coating of nylon and polyester fibers relates to the practice of finishing.

A problem with the finish is that if not removed from the yarn prior to the coating operation, the residual finish can prevent or substantially interfere with the bonding between the coating and the base fiber.

In non-solution dyed yarn, this problem is ameliorated due to other necessary, if not desirable, process steps.

As one might imagine however, bypassing the scouring bath also results in a solution dyed yarn having residual oil from the finishing procedure on its surface.

The traditional low molecular weight nylon coatings can not effectively displace the residual oil from the surface of the solution dyed yarn.

The resulting coating obtained without first removing the residual oil is imperfect and provides insufficient appearance retention.

This additional process step is thus inefficient and costly.