Polymer coating for powder-free elastic strands

Abstract

The present invention is directed to a coated elastomeric sheet or strands having a polymeric coating applied to both sides. The powder-free polymer coating provides good release and anti-blocking properties to elastic strands, as well as adding to the machinability and end-use properties of the strands. The polymer-coated elastic strands are useful in the manufacture of diapers and other disposable articles requiring flexible elastic-lined openings.

Description

[0001] The benefit of the earlier filing date of provisional application No. 60 / 467,382 is claimed.FIELD OF THE INVENTION [0002] The present invention relates to the use of a polymeric coating on powder-free natural or synthetic rubber elastomeric strands and sheets. The polymer coating provides good release and anti-blocking properties to the elastic strips, as well as adding to the machinability and end-use properties of the strands. BACKGROUND OF THE INVENTION [0003] Natural and synthetic rubber is an elastic material that is very tacky and has a low glass transition temperature (Tg). Because of its tackiness, the material adheres to itself and other materials during the manufacturing process, especially prior to curing. A surface coating must be applied to the elastic material to prevent blocking, which is the adhering together of two rubber surfaces, and also to serve as a release coating to prevent the rubber from sticking to objects during manufacture. [0004] In current pract...

AI Technical Summary

Benefits of technology

[0041] One particular advantage of the present invention is that the polymer-coated elastic strips show good bonding with standard hot-melt adhesives. Hot-melt adhesives are often used to attach the elastic strip to a substrate, such as in the use of the elastic strip at the leg opening of a disposable diaper. The presence of a powder coating in the current process hinders the contact between the adhesive and rubber, decreasing bonding efficiency. As a result, high amounts of hot melt adhesive are required. The bonding between the polymer-coated elastic strip and adhesive is excellent, resulting in much better bonding. This results in the use of much less adhesive in the assembly process.

[0042] During the assembly process, the elastic strands are often in direct contact with the adhesive application head. The presence of powder can build-up on, and clog the head, shutting down a production line. The polymer-coated elastic strands of the present invention overcome this process problem.

[0043] Polymer-coated elastic strands may also be used in products such as medical and industrial protective wear such as, for example, gloves, and facemasks. The powder-free polymer coated elastic can be made into strands, threads, and tapes useful in, but not limited to, said listed products.

[0044] The following examples are presented to further illustrate and explain the present invention and should not be taken as limiting in any regard.

Problems solved by technology

Unfortunately, the presence of powder on rubber strands can present problems to both the manufacturer of the rubber strands, and also the manufacturer of end-use products containing the rubber strands.

First, the powders are dusty and easily come off.

Air-borne powder contaminates the air, substrate surfaces, and machinery surfaces.

The dust is an explosion hazard, and build-up on machinery can result in downtime for cleaning.

The powders also tend to adsorb proteins found in natural rubber latex, then when the powder contacts skin or is inhaled, it can cause allergies and other negative effects.

The presence of powder on elastic strips is detrimental to the bonding of those strips to manufactured articles during the end-use assembly process.

The presence of powder on the strands hinders direct contact between the adhesive and the rubber, decreasing bond efficiency.