What Is Copier/Printer Toner Made Of?

Dry xerographic toners consist of a colorant in a binder resin. Beyond these essential ingredients, a particular toner design may contain charge control additives to control the charge level, surface additives to control flow and cleaning properties, magnetic additives to aid in toner control, and waxes to promote toner release from the fuser roll.

  1. Resin

    Several different families of resin (polymers) have found frequent application in xerography depending on the fixing technique selected. The role of the resin in a toner is to bind the pigment to rhe paper or transparency material to form a permanent image. This is typically done by selecting a polymer that will melt at a reasonable temperature when heat is applied in any of a number of ways or one that can be forced into the paper fibers at high pressure without additional heat.

  2. Colorants

    The most common colorant for xerographic toner is carbon black. Most manufacturers offer a range of blacks that differ in such properties as tinting strength and acdity. Important properties of carbon blacks for xerographic applications are their dispersibility in the resin in hot melt mixing and their tendency to charge either positive or negative. Carbon blacks are usually used in toner at a loading of 5 to 15% by weight.

    Besides carbon black there are serveral other materials that can be used to make black toners. Magnetite is often used in toner to allow for magnetic control of the toner. The substance is typically black and is seldom used as pigment per se, but often the loadings for magnetic properties are sufficiently high that additional pigment is not necessary.

  3. Charge Control Additives

    Charge control additives are often added to a toner when the pigment (chosen for its color) blended into the polymer (chosen for its fusing performance) does not give an adequate charge level or rate of charging. This can occur in both positive and negative charging applications.

  4. Surface Additives

    The multifunctional benefits of surface additives such as silicas and titanias have received increased attention in recent years. When materials such as fumed silica are added to the surface of a toner, the flow properties often improve dramatically (Veregin and Bartha,1998). The silicas can also improve transfer from the photoreceptor to paper by lowering the adhesion of the toner to the photoreceptor surface (Akagi et al., 1993) while improving the charge stability of the toner and carrier mixture (Nash and Bickmore, 1988; Stuebbe, 1991). The chemical treatment of silica surfaces has been found to have a profound influence on the properties of toner make with them (Julien et al., 1993; Veregin et al., 1997). In particular, amine treatmens convert silicas from negative to positive charging materials (Takenouchi, 1986; Heinemann and Epping, 1993).

  5. Other Additives

    Fuser rolls typically require the use of a release agent such as silicone oil to prevent the adhesion of the toner to the hot roll surface (Seanor, 1978). Hardware design is simplified if this release agent management system can be eliminated. This both lowers the cost of the machine and eliminates the need for the customer to handle fuser oil. It is possible to do this by incoporating a low molecular weight polyethylene or polypropylene wax into the toner itself (Gruber et al., 1986). This is flows very readily at temperatures sufficient for toner fusing and fills the role of the silicone oil. Partial cross-linking of the polymer in the toner also helps prevent adhesion to the fuser roll (Inoue et al., 1985). This technology is now being used for color toners (Kawaji et al., 1997).