Toner formulations containing extra particulate additives
The present invention relates to toner compositions containing extra particulate additives. The additives may include a mixture of silica particles having differing BET surface areas and may include an acicular inorganic oxide. The control of such additives may be relied upon to control toner performance with respect to functional performance considerations such as filming and/or overall print quality.
1. A toner for an image forming apparatus comprising:
a chemically processed toner including a resin having a particle size in the range of 1 micron to 25 microns and particle additive comprising:
(a) silica particles having a BET surface area greater than 100 m 2/ g which are present in the range of about 0.1 to about 2.0% (wt) of the toner composition, said silica particles having a BET surface area less than 100 m 2/ g which are present at a level of greater than 0.5% (wt); and
(b) acicular inorganic oxide particles present at a level of about 0.5 to about 5.0% (wt) and have a diameter of between about 0.01 to about 10 microns and length of between 1 to 100 microns.
2. The toner of claim 1 wherein said toner particles are present in the range of 1-10 microns in diameter.
3. The toner of claim 1 further comprising a release agent at a concentration greater than 3.0% (wt).
4. The toner of claim 1 further comprising a colorant wherein said colorant is present between about 2-12% (wt.).
5. The toner of claim 1 wherein said resin has a softening point between about 90 to 130° C.
6. The toner of claim 1 wherein said resin comprises a relatively low molecular weight resin and a relatively high molecular weight resin wherein said relatively low molecular weight resin has a Mw of between about 10,000 to 30,000 and said relatively high molecular weight resin comprises a bimodal sample having a Mw of greater than 30,000.
7. The toner of claim 6 wherein said relatively low molecular weight resin is present at greater than 50% (wt) and said relatively high molecular weight resin has a polydispersity index between about 7.1-75.
8. The toner of claim 6 wherein said relatively low molecular weight resin has a polydispersity index between about 1-7 and said relatively high molecular weight resin has a polydispersity index between about 71.-75.
9. The toner of claim 1 wherein said toner comprises a release agent, wherein said release agent has a DSC onset melting temperature of greater than about 40 20 C. and a peak melting point temperature of between about 75 to 105° C.
10. The toner of claim 1 wherein said toner has a complex viscosity ({acute over (η)}) of between about 500 to 1500 Pa·s.
11. The toner of claim 9 wherein said release agent comprises a mean domain size of between about 0.10 to 1.20μm.
12. A method of controlling filming of a CPT toner having a particle size in the range of about 1-25 microns in an image forming apparatus comprising:
(a) adjusting the concentration of silica particles having a BET surface area>100 m 2/ g to a concentration between about 0.1-2.0% (wt);
(b) adjusting the concentration of silica particles have a BET surface area of<100 m 2/ g to a concentration greater than 0.5% (wt);
(c) adjusting the concentration of acicular inorganic oxide particles to a concentration between about 0.5-5.0% (wt).