Composition and process for durably modifying surfaces of normally hydrophobic solid synthetic polymers and cured paints to facilitate spreading of aqueous liquids over the surfaces
AssigneeHenkel Corporation
InventorWalter N. Opdycke
Life of this patent
Estimating the term…
Abstract
Dispersions in water of “poly{vinyl alcohol}” (“PVA”), preferably those types resulting from about 90 mole % hydrolysis and/or ester interchange of polymers of vinyl carboxylates and having a molecular weight of about 155,000, are particularly effective for modifying the surfaces of plastic materials to cause water and/or other specified liquids to spread more readily over the treated surfaces than over the untreated surfaces. A biocide to repress the growth of micro-organisms in the dispersions is preferred.
Claims1
A process for durably improving the spontaneous spreading tendency of at least one specified liquid over a plastic or painted surface, said process comprising steps of:
- (I) maintaining contact for a specified time between the plastic or painted surface and a liquid composition comprising water and at least 0.0040 ppt of poly{vinyl alcohol} (“PVA”), so as to produce a modified plastic or painted surface;
- (II) after completion of step (1), separating the modified plastic or painted surface from any of said liquid composition other than that which fails to drain from the plastic or painted surface under the influence of natural gravity;
- and at least one of:
- (III.1) drying the painted or plastic surface as separated at the end of step (II) or
- (III.2) rinsing the painted or plastic surface as separated at the end of step (II) with a sufficient amount of solvent that any liquid which fails to drain from the surface under the influence of natural gravity after such rinsing has a concentration of PVA that is no greater than 1.0% as much as the concentration of PVA in the liquid composition contacted with the plastic or painted surface in step (I),
- wherein the specified time in step (I) is sufficiently long that at least one of the following two conditions is satisfied:
- (i) a fresh sample of the specified liquid has an advancing contact angle on the modified plastic or painted surface that is smaller than the advancing contact angle that a separate sample of the specified liquid has on a sample of the same plastic or painted surface before modification;
- and (ii) when the modified plastic or painted surface is immersed in the specified liquid and then withdrawn and allowed to drain under the influence of natural gravity for at least one time that is at least 30 seconds in the natural atmosphere at 25° C. with a relative humidity of at least 50%, the fraction of the surface after draining that is covered by the largest single continuous substantially evenly thick covering of the specified liquid on the entire surface is larger than that observed in an otherwise identical test on an unmodified sample of the same plastic surface.
Dependencies are inferred from the claim text.