Browse Prior Art Database

CARBON LOADED POLYMERS

IP.com Disclosure Number: IPCOM000026792D
Original Publication Date: 1993-Aug-31
Included in the Prior Art Database: 2004-Apr-06
Document File: 2 page(s) / 160K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed are electrically conductive composites of carbon black and polymers produced by free radical semi-suspension polymerization processes. Low loadings of carbon black of about (1 to 5 percent by weight of polymer) are utilized to achieve desired conductivity. Examples of polymers made via free-radical polymerization that are useful in combination with carbon black include polystyrene, polymethylmethacrylate, polyvinyl acetate, copolymers thereof, and the like.

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XEROX DISCLOSURE JOURNAL

CARBON LOADED POLYMERS

Marion H. Quinlan Denise Y. Wright

Proposed Classification US. C1.430/109
Int. C1. G03g 09/00

Disclosed are electrically conductive composites of carbon black and polymers produced by free radical semi-suspension polymerization processes. Low loadings of carbon black of about (1 to 5 percent by weight of polymer) are utilized to achieve desired conductivity. Examples of polymers made via free- radical polymerization that are useful in combination with carbon black include polystyrene, polymethylmethacrylate, polyvinyl acetate, copolymers thereof, and the like.

A useful technique for polymerization of pigmented monomer systems is a semi-suspension process. Monomer(s) and initiator($ are mixed and bulk polymerized (that is neat or without solvent) until a desired monomer to polymer conversion (10-40%) is achieved. Alternatively, the pigment could be added to the monomer and dispersed with a high shear mixer, for example, a homogenizer. The initiator(s) is added and this mixture is bulk polymerized to the desired percent conversion. If the pigment was not added prior to bulk polymerization, it is added subsequently and dispersed into the partially converted monomer polymer mixture ("latomer") with a high shear mixer. The partially polymerized pigmented mixture is then dispersed in water containing a stabilizer to form a suspension of latomer particles in water. The suspension product is then transferred to a reactor and polymerized to 100% conversion. Finally, the product is washed and dried.

Carbon black may be substituted for the pigment material in the above described process. During polymerization, the carbon black is believed to be associated with the polymer chain or crystalline domains and may form conductive networks through the polymer matrix. Because of the low loading levels, the carbon black can be easily incorporated into the monomer component without a prohibitive rise in viscosity. In addition, the low loading of carbon black will not inhibit the polymerization. With the use of high shear mixing, carbon black agglomerates can be broken down to form an ink-like dispersion of the carbon black in monomer. Traditionally, carbon black is compounded into polymers after polymerization and pelletizing using extruders, and the like. However, such methods required 15% carbon black to achieve conductivity.

XEROX DISCLOSURE JOURNAL - VOI. 18, NO. 4 July/Auest 1993 465

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CARBON LOADED POLYMERS(Cont'd)

Using semi-suspension processes of the present disclosure to prepare carbon black loaded polymeric materials, structural parts and related components with excellent surface quality, conductivity and mechanical propert...