Method and apparatus for quantifying pigment dispersion quality by paint drawdown

US7639862B2 · kind B2 · utility

Assignee

• E.I. DU PONT DE NEMOURS AND COMPANY · US

Inventors

• Robert Vincent Canning, Jr. · Bear, US
• Scott Richard Mehr · Dickson, US
• Barry Rubin · Glen Mills, US
• Thomas Simpson · Rochester, US
• Douglas Ray Stilwell · Wilmington, US

Key dates

• Filing date: Dec 9, 2005
• Grant date: Dec 29, 2009
• Expiry date: Jan 22, 2028

Classification

• Technology area (CPC G): Physics
• CPC primary: G06T2207/30108
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An automated computer-controlled method and apparatus for measuring the quality or fineness of a pigment dispersion sample, comprising placing the pigment dispersion at the deep end of the tapered path of a Hegman gage block, placing the Hegman gage block in a holder in a motorized drawdown device that draws the scraper along the length of the tapered path at an angle and to at a contact pressure and at a controlled rate, thereby creating a tapered film sample of paint whose thickness tapers from a maximum thickness of 100 micrometers to a minimum thickness of zero. An illuminator assembly illuminates the sample with a substantially collimated light source at an intensity level and the light reflected from the sample is collected by a lens onto a photodetector array in a digital camera. After a time interval the camera acquires an image of the sample. The image is digitized and stored in a memory in the computer and then a portion of the image within a region of interest corresponding to the sample in the tapered path is analyzed to detect and count pigment agglomerates that protrude above the surface of the sample.