Method for coating a five-sided container with sag-resistant water-based coating compositions

Patent metadata

Field	Value
Publication number	US-9815083-B2
Application number	US-201615046554-A
Country	US
Kind code	B2
Filing date	Feb 18, 2016
Priority date	Mar 8, 2011
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

The present invention provides a water-based coating and/or coating system used to form sag resistant wet layers or coatings on a wide range of substrates. The coating system is effective for protecting metal-containing substrates, such as intermodal cargo containers, against corrosion. As an overview, the present invention provides water-based compositions as primer coats on substrates, and methods for applying the same to substrates. The method includes steps of applying a water-based paint to the interior surfaces of a substrate and drying the substrate by continuously forcing heated air onto the substrate as it moves through a drying chamber. Desirably, the primer incorporates a high level of one or more CAS agents for excellent sag resistance while drying in a broad range of relative humidity environments. Alternatively, modifications can be made to control temperature and humidity during spray application and drying as a way to increase sag resistance of the coating.

First claim

What is claimed is:

1. A method, comprising:
providing a five-sided container, the container including an open side, a first steel wall opposite the open side, and four steel side walls connected to the first wall, wherein the side walls extend in a first direction with respect to the first wall, and wherein each of the first wall and the four side walls have an interior surface;
applying a water-based paint to the interior surfaces of the first wall and the side walls of the container; and
continuously forcing heated air at a temperature of about 50 to 200° C. and a velocity of about 0.1 to 10 m/s into the open side of the container as the container moves through a drying chamber to at least partially dry the paint on the interior surfaces of the container, wherein the heated air is directed such that the heated air:
travels in a second direction opposite to the first direction to contact an interior surface of the first wall and flows in a third direction and a fourth direction thereover, wherein the third direction and the fourth direction are substantially opposite one another and substantially normal to the second direction and the first direction;
flows in the first direction along the interior surfaces of the walls of the container; and
exits the container.

2. The method of claim 1 , wherein the heated air is forced into the container for less than about 20 minutes.

3. The method of claim 1 , wherein applying a water-based paint comprises:
applying at least one primer coat to the interior surfaces of the container, wherein the primer coat comprises a dried coating prepared from a coating composition including
an aqueous carrier;
a first resin component comprising polyvinylidene chloride in admixture with the aqueous carrier;
at least one aqueous epoxy-functional compound; and
one or more fillers; and

optionally, applying at least one topcoat over the primer coat.

4. The method of claim 3 wherein the primer coat has dry film thickness of about 20 to 100 μm.

5. The method of claim 1 , wherein the five-sided container is an intermodal cargo container.

6. The method of claim 5 , wherein the intermodal cargo container substantially conforms to ISO R-668.

7. The method of claim 1 , wherein the partially dry paint has a film thickness of 20 to 100 μm.

8. A method, comprising:
providing a five-sided container substantially conforming to ISO R-668, the container including an open side, a first steel wall opposite the open side, and four steel side walls connected to the first wall, wherein the side walls extend in a first direction with respect to the first wall, wherein each of the first wall and the four side walls have an interior surface, and wherein the interior surfaces of the first wall of the container and the interior surfaces of at least two side walls of the container intersect to form corner regions;
applying a water-based paint to the interior surfaces of the first wall and the side walls of the container; and
allowing the paint to dry to a film thickness of about 20 to 100 μm in an environment having a relative humidity in the range of up to about 95% by forcing heated air into the open side of the container as the container moves through a drying chamber for about 10 to 30minutes, wherein the heated air is directed such that the heated air:
travels in a second direction opposite to the first direction and enters the open side of the container at a velocity sufficient to provide substantially laminar flow along the interior surface of the first wall of the container, and flows in a third direction and a fourth direction thereover, wherein the third direction and the fourth direction are substantially opposite one another and substantially normal to the second direction and the first direction;
flows in the first direction along the interior surfaces of the walls of the container; and
exits the container.

9. The method of claim 8 , wherein the relative humidity is in the range of 50% to 85%.

10. The method of claim 8 , wherein the relative humidity is in the range of 50% to 75%.

11. A method, comprising:
providing a five-sided container substantially conforming to ISO R-668, the container including an open side, a first steel wall opposite the open side, and four steel side walls connected to the first wall, wherein the side walls extend in a first direction with respect to the first wall, and wherein each of the first wall and the four side walls have an interior surface;
applying a water-based paint as a primer coat to the interior surfaces of the first wall and the side walls of the container in process conditions modified to control humidity and temperature, wherein the water-based paint comprises
an aqueous carrier;
a first resin component comprising polyvinylidene chloride in admixture with the aqueous carrier;
one or more aqueous epoxy-functional compounds;
one or more fillers; and
one or more CAS agents dispersed in the aqueous carrier, wherein the one or more CAS agents are present in a sufficient amount to provide the water-based paint with sag resistance at 80% relative humidity and 25° C. that is at least 60% of the sag resistance of the water-based paint at 50% relative humidity and 25° C.; and

forcing heated air into the open side of the container as the container moves through a drying chamber to at least partially dry the paint to a film thickness of about 20 to 100 μm on the interior surfaces of the container, wherein the heated air is directed such that the heated air
(i) travels in a second direction opposite to the first direction to contact an interior surface of the first wall and flows in a third direction and a fourth direction thereover, wherein the third direction and the fourth direction are substantially opposite one another and substantially normal to the second direction and the first direction;
(ii) flows in the first direction along the interior surfaces of the walls of the container; and
(iii) exits the container.

12. The method of claim 11 , wherein the one or more CAS agents comprise hydrophilic clay and are present in an amount greater than 0.12 kg per 100 L of the water-based paint.

13. The method of claim 11 , wherein the one or more CAS agents comprise bentonite.

14. The method of claim 11 , wherein the one or more CAS agents have average particle size less than 1 μm.

15. The method of claim 11 , wherein the water-based paint is substantially free of associative thickener(s).

Assignees

• Valspar Sourcing Inc

Inventors

• Beaudry Channing Charles
• Nowack William C
• Prevost James A
• Zhang Feng
• Wetzel Wylie H

Classifications

• C09D5/024

  characterised by the additives · CPC title

• C09D5/04

  Thixotropic paints · CPC title

• F26B21/006

  with the air or gases passing through hollow spaces or cores within the materials or objects to be dried, e.g. tubes, pipes or bottles · CPC title

• C09D127/08 Primary

  Homopolymers or copolymers of vinylidene chloride · CPC title

• B05D2520/00

  Water-based dispersions · CPC title