US 4,515,836 A · Process for coating substrates with aqueous polymer dispersions

Abstract

A process for providing a substrate such as a polyethylene terephthalate container with a gas barrier coating of a copolymer of vinylidene chloride is disclosed. The process includes locating the container to be coated in close proximity to one or more airless spray nozzles and impacting the outside surface of the container with a stream of a stabilized aqueous polymer dispersion such as an aqueous polyvinylidene chloride dispersion. The impacting force of the stable polyvinylidene chloride dispersion on the surface of the container is sufficient to cause selective destabilization of the dispersion at the surface interface to form a gel layer containing the polymer in the continuous phase. This gel layer serves as an adhesive layer for an overlying layer of the aqueous polymer dispersion as a continuous uniform coating. The resulting wet coating does not sag or run off. The coating on the container is then dried in a controlled atmosphere to complete the gel formation throughout its thickness whereupon it is further dried to remove the water from the coating and to collapse the gel to form a film without distoring the container. The dried coating is smooth, uniform and uniformly transparent. In operation, the overspray can be collected and returned to achieve greater than 95% material efficiency. The process can be carried out in a continuous manner to provide a continuously moving series of containers with a uniformly transparent, gas barrier polyvinylidene chloride coating at production rates suitable for commercial applications.

Claims28

Dependent claims

A process for coating a substrate with a uniform polymeric coating comprising

providing a substrate having a surface to be coated,
impacting said surface with a stream of a stabilized dispersion of polymer in water,
initially forming on said surface a gel coating layer bonded to said surface and caused by destabilization of said dispersion upon said impact,
thereafter continuing to expose the gelled coating layer to said stream of stabilized polymer dispersion to produce a wet integral coating including a covering layer of polymer dispersion completely covering said gel layer, said gel layer serving as an interfacial layer to adhere said covering layer of polymer dispersion to said substrate,
heating said wet integral coating to form a substantially completely gelled coating throughout its thickness on said surface, and
further heating said gelled coating to coalesce said polymer into a substantially uniform coating on said substrate.

3 more elements

Dependencies are inferred from the claim text.

Process for coating substrates with aqueous polymer dispersions

Life of this patent

Process for coating substrates with aqueous polymer dispersions

Life of this patent

Abstract

Claims28