Short dwell time coater and method
OwnerWayne A. Damrauinventor
Life of this patent
Estimating the term…
Abstract
An improved short dwell type coater and method are provided. The coater can coat a web directly or a moving roll surface as in a film coater or size press. The flow path in the coater includes a flow modifier shaped to have the introduced coating first turn upstream relative to the web or roll surface, then turn across a curved surface toward the web or roll and around the flow modifier. The flow then converges toward the top of the flow modifier and passes the tip of the flow modifier. Some flow remains on the web or roll and is subsequently doctored, while most is turned away from the web or roll and merged with the incoming flow. A gap filled with coating overflow provides a liquid seal. This coater and method use coating, reduce vortices and streaking, and can operate at higher speeds.
Claims88
A method for applying a coating to a moving surface, comprising the steps of supplying coating under pressure to a coater head, causing the coating to flow downstream against the direction of moving surface travel, causing the coating to flow toward the moving surface, applying some of the coating to the surface, the other of the coating turning away from the moving surface toward the local where the coating first flowed in a direction downstream of the moving surface, merging the returning coating with the coating flowing in a downstream moving direction, directing the coating applied to the moving surface toward a doctor, removing some of the coating applied to the moving surface with the doctor and permitting the remainder of the coating of a desired coat weight to pass by the doctor, whereby the coating applied to the moving surface has a reduced tendency to form vortices therein and streaking.
A coater for applying a coating to a moving surface, comprising a coater head for supplying coating under pressure to the moving surface, said coater having a flow path for causing the coating to flow downstream against the direction of moving surface travel, said flow path turning toward the moving surface for causing the coating to flow toward the moving surface, said coater head having an application zone adjacent the moving surface for applying at least some of the coating to the moving surface, the coater head having a return path flowing from the application zone toward the flow path where the coating first flowed in a direction downstream of the moving surface, the return path merging into the flow path and the returning coating flowing in a downstream direction away from the moving surface, a doctor at the rear of the application zone for removing some of the coating applied to the moving surfaces with the doctor and permitting the remainder of the coating of a desired coat weight to pass by the doctor, whereby the coater can apply coating to the moving surface with a reduced tendency to form vortices therein and streaking.
A method for applying a coating to a moving surface, comprising the steps of supplying coating under pressure to a coater head, causing the coating to flow from downstream against the direction of moving surface travel, causing the coating to flow toward the moving surface, causing an overflow of coating from that headed toward the moving surface to wet the moving surface before it enters the coater, adjusting the amount of overflow to a desired level, applying some of the coating to the surface, flowing the coating downstream of the direction of web travel, and returning the same applied coating to said local, comprises the step of causing the coating to turn around a flow member, the other of the coating turning away from the moving surface toward said local where the coating first flowed in a direction downstream of the moving surface, merging the returning coating with the coating flowing in a downstream moving direction, causing the coating to flow upstream of the direction of web travel includes the step of passing the coating by supports for locating a flow member, directing the coating applied to the moving surface toward a doctor, removing some of the coating applied to the moving surface with the doctor and letting the remainder of the coating of a desired coat weight pass by the doctor, whereby the coating applied to the moving surface has a reduced tendency to form vortices therein and streaking.
A coater for applying a coating to a moving surface, comprising a coater head for supplying coating under pressure to the moving surface, said coater head having a flow path for causing the coating to flow downstream against the direction of moving surface travel, said flow path turning toward the moving surface for causing the coating to flow toward the moving surface, said coater head having an application zone adjacent the moving surface for applying at least some of the coating to the moving surface, the coater head having a return path flowing from the application zone toward the flow path where the coating first flowed in a direction downstream of the moving surface, the return path merging into the flow path and the returning coating with the coating flowing in a downstream moving surface direction, a flow member generally surrounded by the flow path, the application zone and the return path, whereby the coating can flow around said flow member, a spaced gap between the moving surface and coater head for permitting an overflow of coating from that headed toward the moving surface to wet the moving surface as it enters the coater, means for adjusting the amount of overflow through the gap to a desired level, supports for locating a flow member in said application zone, said support being attached with said coater head, a doctor at the rear of the application zone for removing some of the coating applied to the moving surface with the doctor and letting the remainder of the coating of a desired coater weight pass by the doctor, whereby the coater can apply coating to the moving web with a reduced tendency to form vortices therein and streaking.
Dependencies are inferred from the claim text.