Colourless charge controllers for use in toners

摘要

A charge-controller for use with a toner contains a polymer with a dielectric loss tangent at 100 kHz of 0.008-0.3 and a water absorption capacity of at most 10 wt.%, the polymer being based on ethylenically unsaturated monomers and being (A1) a polymer of a monomer having an aromatic ring substituted by one or more electron-attracting group such as halogen, nitrogen dioxide or cyano; and/or (A2) a copolymer of a monomer with an organic acid or salt group. Also claimed is charge controller composition comprising polymer (A1) and/or (A2) plus a salt of a perfluoroalkyl group-containing organic acid. Preferably polymer (A1) contains at least 5wt.% of units derived from the aromatic monomer which is a styrene or an aromatic ring-containing maleimide, itaconamide, (meth)acrylate, (meth)acrylamide or vinyl ether, each of these monomers being substituted as per (A1) above. The monomer for (A1) is especially a substituted phenyl-maleimide or phenylitaconamide and it can be copolymerised with 0.1-20 wt.% units derived from an organic acid (or salt)-containing monomer and/or 10-94.9 wt.% units derived from a perfluoroalkyl- or Si-group-containing monomer. Copolymer (A2) contains 0.1-20 wt.% of the organic acid-(or salt)-containing monomer and 80-99.9 wt.% units derived from another (preferably perfluoroalkyl- or Si-group-containing) monomer, the acid monomer containing a sulphonic acid, sulphaminic acid, sulphate acid, carboxylic acid or phosphate acid group (or an alkali(ne earth), amine or ammonium salt) and especially being a styrene sulphonic acid or a sulphophenyl-acrylamide.