Coating processes – Measuring – testing – or indicating
Utility Patent
1999-11-22
2001-01-02
Bareford, Katherine A. (Department: 1762)
Coating processes
Measuring, testing, or indicating
C427S345000, C427S421100, C137S004000, C137S007000, C137S092000, C239S075000, C239S101000
Utility Patent
active
06168824
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for regulating the viscosity of a liquid paint in an automotive vehicle paint application system. In particular, the present invention relates to a method wherein the viscosity of the liquid paint in an automotive vehicle paint application system is continuously monitored and may be continuously regulated on a real time basis.
BACKGROUND OF THE INVENTION
In automotive coating, the so-called clear coat technique (sometimes referred to as two-coat one-bake technique) is employed which comprises applying a metallic base paint composition, called a top coat, containing a metallic pigment, to a steel substrate or other material. The steel substrate or other material is provided in advance with undercoat and intermediate coat primers. Then, without curing of the resulting top coat paint film, a clear paint composition is applied over the top coat in a wet-on-wet manner. The top coat and clear paint are then cured simultaneously.
The prior art paints used in said two-coat one-bake technique are mostly organic solvent based. However, from the viewpoints of safety during coating, reduction of environmental pollution and preserving resources, among others, water-based paints have been earnestly desired in recent years. For this purpose, various water-based paints have been developed for automobile coating.
Various curing systems for water-based clear coating paints have been proposed. They include, curing systems containing a hydroxyl group (including a blocked hydroxyl group), a carboxyl group (including a blocked carboxyl group wherein the hydroxyl group of the carboxyl group is blocked), a phosphoric acid group (including a blocked phosphoric acid group wherein the hydroxyl group of the phosphoric acid group is blocked) or an acid anhydride group; curing systems containing such a group as described above and also a silyl group (including a hydrolyzable silyl group blocked with a hydrolyzable group) and/or an epoxy group; curing systems containing an acetoacetyl group and a vinyl ether group or a vinyl thio ether group (hereinafter referred to simply as a vinyl (thio) ether group); curing systems containing a vinyl (thio) ether group and a carboxyl group or a silyl group; curing systems containing an alicyclic epoxy group and a silyl group; and curing systems containing a silyl group or an alicyclic epoxy group singly. In such curing systems, a curing catalyst is usually used to accelerate the curing reaction of the functional groups.
In the clear coat technique, the clear coat paint and the base coat paint (top coat) are stored separately in storage vessels until immediately before the coating thereof of the automotive vehicle.
In most auto plant assembly paint systems a plurality of colors are available for instant use. Each color requires a separate base coat application system and conventionally, each application system includes a circulation network wherein a circulation pump causes the base paint to flow through the network conduits. The network includes a plurality of base paint distributors, such as spray guns or spray nozzles, which may be fixed, robotically operated or hand held, and one or more of the paint distributors may be in operation at a time. It is necessary to design the application system to be capable of handling sufficient paint if all the distributors are in operation simultaneously, but usually only a small percentage of the capacity of the application network is used at any one time.
The base paint application system is basically “closed” wherein the base paint circulates in a loop, and it is necessary to add base paint to the loop to replace that ejected from the nozzles. The circulation of the base paint in the application system is at a high rate and the base paint will be cycled many times if usage is low. Problems have been experienced with existing paint circulation systems with respect to paint particles settling within the network conduits, and degradation of the base paint occurs during extended circulation, including the degradation of metallic flakes and the like which may be added to the paint for aesthetic purposes. Additionally, existing paint application systems do not permit a ready indication of the viscosity of the base paint. As viscosity changes, the quality of the applied paint will change, and to provide optimum results, viscosity of the paint must be continuously known.
As mentioned previously, quality automotive paint finishing requires precise control of all parameters, paint viscosity being the highest priority. Prior to the present invention, to insure uniform paint viscosity, the paint application operator would measure and adjust the viscosity by adding various solvents as required. The viscosity was typically measured manually using either a Brookfield Viscometer or a #4 Ford Cup after taking a sample from the automotive vehicle paint application system's batch tank. Specialized instruments are available for measuring viscosity without utilizing a Brookfield Viscometer or #4 Ford Cup. However, such instruments are expensive and typically require frequent calibration. It is desirable to provide a method of continuously monitoring the viscosity of paint in an automotive vehicle body paint application system which does not require manual operation or the utilization of very expensive instrumentation requiring frequent calibration.
SUMMARY OF THE INVENTION
To meet the above-noted and other unfulfilled desires, the revelation of the present invention is brought forth. The present invention makes manifest a freedom of continuously monitoring the viscosity of liquid paint in an automotive vehicle paint application system without manual intervention. The present inventive viscosity monitoring method provides liberty from expensive instrumentation requiring frequent calibration. In a preferred embodiment the present invention additionally provides a method of regulating the viscosity of a liquid paint in an automotive vehicle paint application system. The method includes delivering paint to the paint application system with a pump. Continuously monitors the pressure that the paint is delivered to the paint application by the pump. Returning the paint which is not applied to the automotive vehicle by the paint application system through a return line. Continuously monitoring the pressure of the paint flowing through the return line. Continuously measuring the flow rate of the paint returning through the return line. Continuously calculating the viscosity from the pressure differential between the delivery pressure and the return line pressure and the flow rate in the return line and the fluid resistance of the paint application system to determine the viscosity of the paint. Delivering the paint from the return line to a sump. Adding thinners to the paint to cause the paint to have a predetermined regulated level of viscosity.
It is an object of the present invention to continuously monitor the viscosity of a liquid paint in an automotive vehicle paint application system.
It is an object of the present invention to provide a method of regulating the viscosity of a liquid paint in an automotive vehicle paint application system.
The above noted and other objects of the present invention will become apparent to those skilled in the art from a review of the invention as it is provided in the accompanying drawing and detailed description of the preferred embodiment.
REFERENCES:
patent: 2762652 (1956-09-01), Carter
patent: 3282323 (1966-11-01), Katz et al.
patent: 4263091 (1981-04-01), King
patent: 4278205 (1981-07-01), Binoche
patent: 4592305 (1986-06-01), Scharfenberger
patent: 4738219 (1988-04-01), Fujisawa
patent: 4878649 (1989-11-01), Baba et al.
patent: 5096120 (1992-03-01), Luckarz
patent: 5330783 (1994-07-01), Saidman et al.
patent: 5433587 (1995-07-01), Bankert et al.
Barlow Timothy A.
Rozan Wayne T.
Bareford Katherine A.
DaimlerChrysler Corporation
Shurupoff Lawrence J.
LandOfFree
Paint viscosity measuring system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Paint viscosity measuring system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Paint viscosity measuring system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2491542