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Modified Polystyrenes for Electrophotography

IP.com Disclosure Number: IPCOM000086344D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Adams, JM: AUTHOR [+3]

Abstract

A chemical treatment or modification of polystyrene is described which increases the tribonegativity, or net negative charging ability of electrophotographic toner resins. This result can be accomplished by chemical treatment of toner resins containing polystyrene to substitute the benzene with nitro groups, or alternatively, to substitute for polystyrene with nitro-polystyrene in the homopolymer or copolymer resins used in toner manufacture.

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Modified Polystyrenes for Electrophotography

A chemical treatment or modification of polystyrene is described which increases the tribonegativity, or net negative charging ability of electrophotographic toner resins. This result can be accomplished by chemical treatment of toner resins containing polystyrene to substitute the benzene with nitro groups, or alternatively, to substitute for polystyrene with nitro-polystyrene in the homopolymer or copolymer resins used in toner manufacture.

The effects of nitration on triboelectric characters have been assessed by examining nitrated polystyrene beads (BIOBEADS* SX-2) in an electrophotographic charge/mass measuring device, which mimics the transfer of toner particles from a developer mixture to an image on the photoconductor.

SX-2 BIOBEADS (200-400 mesh spheres of polystyrene cross-linked with 2% divinyl benzene) (1g) were treated with red fuming nitric acid (86%) (10 mil) for 30, 60, or 90 minutes. The product was recovered by filtration on a sintered glass funnel followed by a water and methanol wash.

It was found to contain 1.0 nitro groups per phenyl on the basis of pyrolysis gas chromatography and elemental analysis (% N found, 9.49.6). Additionally, ESCA showed.the presence of NO groups on the surface of the particles, with an N/O ratio of 2.2. Thus, nitration occurs throughout the particles and at the surface, with predominant mononitration. The interstitial regions of the beads contained water (4.3g in 13.2g beads).

Untreated BIOBEADS (0.5g) were used as toner and agitated with carrier (50g). The toner particles were charged to 1.0 x 10/4/ esu/gram, indicating a net negative charge on the toner. After nitric acid treatment the charge measured on the toner particles was in excess of 70 x 10/4/ esu/gram. The extent to which the Q...