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Elimination of Coating Voids Resulting from Dip Coating Process

IP.com Disclosure Number: IPCOM000102999D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Merten, RA: AUTHOR [+3]

Abstract

Disclosed is a method to eliminate small coating voids which occur while dip-coating transport layer on organic photoconductor drums. The use of a low viscosity dimethyl siloxane flow agent has been found to be very effective in reducing these imperfections in the coated film.

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Elimination of Coating Voids Resulting from Dip Coating Process

      Disclosed is a method to eliminate small coating voids which
occur while dip-coating transport layer on organic photoconductor
drums.  The use of a low viscosity dimethyl siloxane flow agent has
been found to be very effective in reducing these imperfections in
the coated film.

      Dip-coating of organic coatings is considered a low shear
application technique.  Because of the low shear stress applied to
the fluid being coated, the liquid remains in a higher viscosity
state during the coating process than normally occurs with other
coating processes, such as spray, brush or roller coat.  The
combination of low shear on the liquid and higher viscosity results
in a lower "spreading force" when dip-coating.  As a consequence,
surface areas which are more difficult to wet because of
contamination or planar irregularities, are more susceptible to the
formation of voids, fisheyes, etc., when dip-coated.

      The use of silicone flow agents to eliminate coating
nonuniformities has been known for some time.  However, it has not
been realized that the lower viscosity dimethyl siloxane flow agents
are more effective in low-shear dip-coating applications than the
higher viscosity flow agents.  Specifically, 100 centistokes grade
DC-200 (Trademark of Dow Corning Corp.) has been found to be much
more effective in the elimination of coating voids in dip-coating
applications of high molecular weig...