Environmental Project, 901 – Evaluation of alternatives for compounds under risk assessment in the EU, Bisphenol A

Evaluation of Alternatives for Compounds under Risk Assessment in the EU, Bisphenol A

6 Toners

Toners are used in copying and non-impact printing processes, i.e. in office copiers, plain paper fax machines, digital printers and copiers.

These machines print by a method called electrophotography. In electrophotography, a charge pattern replicating the light image is formed on a photoconductive film. Charged pigmented thermoplastic particles (toner) are attracted to the charged areas of the photoconductive film from where it is transferred to the paper onto which the toner is fixed by softening and fusing the toner to the paper (Ullmann, 2002).

Toners are thermoplastic particles, typically 5-25 m in size with 5-10% of pigment to give the desired colour. The function of the thermoplastic is to fix and fuse the image onto the paper, which is done by heat and/or pressure (Ullmann, 2002).

Typical thermoplastics used in toners are random copolymers of styrene with methacylates or acrylates. Some toners contain a small percentage of very large thermoplastic particles (100-700 m) called beads, which carry many small toner particles (Ullmann, 2002).

Xerox is one of the toner suppliers, from which the products contain bisphenol A. E.g. in the Xerox Cyan developer (i.e. DocuColor 12, Document Centre colorSeries 50, DocuColor 2045, DocuColor 2060, DocuColor 6060), there is <7% wt. toner of which 80-90% wt. is a bisphenol A polyester resin (CAS No. 122970-65-4) (Xerox, 2003B). An example of the structure of a bisphenol A polyester resin is shown in Figure 6.1. Whereas, in the Xerox Dry ink document centre 240DC/STx, a bisphenol A propylene oxide fumarate polymer (CAS No. 39382-25-7) constituting 60-75% (wt/wt). is used and the same polymer is used in other dry inks and magnetic toners produced by Xerox (Xerox, 2003A). Also Lexmark uses bisphenol A polyester resins in their toners (Lexmark, 2002).

Figure 6.1 Bisphenol A dimethyl terephthalate polyester resin

Figure 6.1 Bisphenol A dimethyl terephthalate polyester resin

Polyesters are macromolecules prepared from different diabasic acids (e.g. isophthalic, orthophthalic, terephthalic acids, fumaric/maleic acids) and diols (dihydric alcohol) such as ethylene glycol, propylene glycol, neopentyl glycol, bisphenol A (BPA) etc. Polyester resins are generally divided into ortho resins, iso-resins, BPA fumarates and vinyl ester resins. Due to differences in their structures different combinations of these di-acids & diols impart variation in mechanical properties like flexural strength, tensile strength and compressive strength.

Bisphenol A seems only to appear in toners as part of a polymer/resin.

There were no alternatives to the bisphenol A polymer/resins related to the production or use of toners, and thus no industrial input to the list of possible alternative substances available from the DPR (Tables 3.6 and 3.7).