A fuser member useful for heat-fixing an electrographic toner to a substrate. The fuser member has a core and a layer overlying the core. That layer includes a cured fluorocarbon random copolymer having subunits with the general structures:
where x is from 30 to 90 mole percent, y is from 10 to 70 mole percent, and z is from 0 to 34 mole percent. The layer incorporates particulate filler. The filler includes aluminum oxide and a material selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, and combinations thereof. The filler has a total concentration in the layer of from about 25 to 50 percent of the total volume of the layer. The aluminum oxide has a concentration of from 20 to 40 percent of the total volume of the layer.
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0. 14. A fuser member comprising a core and a layer overlaying said core, said layer comprising: a cured fluorocarbon random copolymer comprising subunits having the general structures:
wherein
x is from 30 to 90 mole percent, y is from 10 to 70 mole percent, and z is from 0 to 34 mole percent, said layer further comprising particulate filler, said particulate filler including aluminum oxide and a material selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, and combinations thereof; said layer having a thermal conductivity in the range of about 0.15 to 0.40 BTU/hr·ft·°CF.
1. A fuser member comprising a core and a layer overlying said core, said layer comprising: a cured fluorocarbon random copolymer comprising subunits having the general structures:
wherein
x is from 30 to 90 mole percent, y is from 10 to 70 mole percent, and z is from 0 to 34 mole percent; said layer further comprising particulate filler, said particulate filler including aluminum oxide and a material selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, and combinations thereof; said particulate filler having a total concentration in said layer of from about 25 to 50 percent of the total volume of said layer, said aluminum oxide having a concentration of from 20 to 40 percent of the total volume of said layer.
0. 22. A fuser member useful for heat-fixing an electrographic toner to a substrate, said fuser member comprising: a core, a base cushion superimposed on said core and an outer layer superimposed on said base cushion, said outer layer comprising a bisphenol cured fluorocarbon random copolymer comprising subunits having the general structures:
wherein
x, y, and z are selected such that fluorine atoms represent at least 70 percent of the total formula weight of said subunits; said outer layer having filler particles dispersed therein, said filler particles further comprising: particles selected from the group consisting of alkaline earth metal oxides and alkaline earth metal hydroxides; and aluminum oxide particles;
said outer layer having a thermal conductivity in the range of about 0.15 to 0.40 BTU/hr·ft·°CF.
0. 24. A fuser member useful for heat-fixing an electrographic toner to a substrate, wherein the roll comprises a core, a base cushion layer overlying said core, and an outer layer superimposed on said base cushion, said outer layer comprising a cured fluorocarbon random copolymer comprising subunits having the general structures: subunits having the general structures:
wherein
x is from 10 to 90 mole percent, y is from 10 to 70 mole percent, and z is from 0 to 34 mole percent; said outer layer further comprising particulate filler, said particulate filler including aluminum oxide and a material selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, and combinations thereof; and said outer layer having a thermal conductivity in the range of about 0.15 to 0.40 BTU/hr·ft·°CF.
9. A fuser member useful for heat-fixing an electrographic toner to a substrate, said fuser member comprising: a core, a base cushion superimposed on said core and an outer layer superimposed on said base cushion, said outer layer comprising a bisphenol cured fluorocarbon random copolymer comprising subunits having the general structures:
wherein
x, y, and z are selected such that fluorine atoms represent at least 70 percent of the total formula weight of said subunits; said outer layer having filler particles dispersed therein, said filler particles further comprising: particles selected from the group consisting of alkaline earth metal oxides and alkaline earth metal hydroxides in a concentration of from about 5 to 20 percent of the total volume of said outer layer; and aluminum oxide particles in a concentration of from 20 to 40 percent of the total volume of said outer layer.
12. A fuser member useful for heat-fixing an electrographic toner to a substrate, wherein the roll comprises a core, a base cushion layer overlying said core, and an outer layer superimposed on said base cushion, said outer layer comprising a cured fluorocarbon random copolymer comprising subunits having the general structures:
wherein
x is from 10 to 90 mole percent, y is from 10 to 70 mole percent, and z is from 0 to 34 mole percent; said outer layer further comprising particulate filler, said particulate filler including aluminum oxide and a material selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, and combinations thereof; said particulate filler having a total concentration in said outer layer of from about 25 to 50 percent of the total volume of said outer layer, said aluminum oxide having a concentration of from 20 to 40 percent of the total volume of said outer layer.
2. The fuser member of
5. The fuser member of
6. The fuser member of
10. The fuser member of
11. The fuser member of
13. The fuser member of
0. 15. The fuser member of
0. 16. The fuser member of
0. 17. The fuser member of
0. 18. The fuser member of
0. 19. The fuser member of
0. 20. The fuser member of
0. 21. The fuser member of
0. 23. The fuser member of
0. 25. The fuser member of
0. 26. A method which comprises using a fuser member according to
0. 27. A method which comprises using a fuser member according to
0. 28. A method which comprises using a fuser member according to
0. 29. A method which comprises using a fuser member according to
0. 30. A method which comprises using a fuser member according to
0. 31. A method which comprises using a fuser member according to
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alkali
The fuser roll of the invention has a core, a base cushion superimposed on the core and an outer layer superimposed on the base cushion.
The outer or "overcoat" layer comprises a cured fluorocarbon random copolymer having subunits with the following general structures:
In these formulas, x, y, and z are mole percentages of the individual subunits relative to a total of the three subunits (x+y+z), referred to herein as "subunit mole percentages". (The curing agent can be considered to provide an additional "cure-site subunit", however, the contribution of these cure-site subunits is not considered in subunit mole percentages.) In the fluorocarbon copolymer, x has a subunit mole percentage of from 30 to 90 mole percent, y has a subunit mole percentage of from 10 to 70 mole percent, and z has a subunit mole percentage of from 0 to 34 mole percent. In a currently preferred embodiment of the invention, subunit mole percentages are: x is from 40 to 80, y is from 10 to 60, and z is from 0 to 34; or more preferrably x is from 42 to 75, y is from 14 to 58, and z is 0. In the currently preferred embodiments of the invention, x, y, and z are selected such that fluorine atoms represent at least 70 percent of the total formula weight of the VF, HFP, and TFE subunits.
The outer layer includes particulate filler comprising aluminum oxide and additional particulate selected from alkaline earth metal oxides, alkaline earth metal hydroxides, and combinations of alkaline earth metal oxides and hydroxides. In a currently preferred embodiment of the invention, the additional particulate is a mixture of magnesium oxide and calcium hydroxide. The particulate filler has a total concentration in the outer layer of from about 25 to 50 percent of the total volume of the outer layer. The aluminum oxide has a concentration of from about 20 to 40 percent of the total volume of the outer layer. The aluminum oxide particles comprise from 20 to 40 percent of the total volume of the base cushion layer. Concentrations of aluminum oxide of less than 20 volume percent may not provide the degree of stability desired to the layer. Concentrations of aluminum oxide of greater than 40 volume percent will render the layer too hard to provide the desired area of contact with the toner-bearing receiver sheet. In a particular embodiment of the invention, the outer layer has 3 volume percent MgO, 6 volume percent Ca(OH)2 and from 20 to 40 volume percent aluminum oxide. The aluminum oxide particles comprise from 20 to 40 percent of the total volume of the base cushion layer.
The aluminum oxide particles employed as filler in the base cushion layer of a fuser member of the invention can be obtained from any convenient commercial source, e.g., Magnesium Electron, Inc. of Flemington, N.J. The particle size does not appear to be critical. Particle sizes anywhere in the range of 0.1 to 100 micrometers have been found to be acceptable. In the examples presented below the aluminum oxide particles were from 1 to 40 micrometers in diameter.
To form the outer layer, the filler particles are mixed with the uncured polymer, crosslinking agent, and any other additives, such as an accelerator; shaped over the base cushion, and cured. The fluorocarbon is cured by crosslinking with basic nucleophile. Basic nucleophilic cure systems are well known and are discussed, for example, in U.S. Pat. No. 4,272,179. One example of such a cure system combines a bisphenol as the crosslinking agent and an organophosphonium salt, as an accelerator. An example bisphenol is:
An example organophosphonium salt is:
The crosslinker is incorporated into the polymer as a cure-site subunit, for example, bisphenolic residues. Other examples of nucleophilic addition cure systems are sold commercially as DIAK No. 1 (hexamethylenediamine carbamate) and DIAK No. 3 (N,N'-dicinnamylidene-1,6-hexanediamine) by E. I. duPont de Nemours & Co.
Suitable uncured polymers are available commercially. In a particular embodiment of the invention, a vinylidene fluoride-co-hexafluoropropylene was used which can be represented as -(VF)75-(HFP)25-. This material is marketed by E. I. duPont de Nemours and Company under the designation "Viton A" and is referred to herein as "Viton A". In another embodiment of the invention, a vinylidene fluoride-co-hexafluoropropylene was used which can be represented as -(VF)42-(HFP)58-. This material is marketed by Minnesota Mining and Manufacturing, St. Paul, Minn., under the designation "Fluorel FX-2530" and is referred to herein as "FX-2530". Other suitable uncured vinylidene fluoride-co-hexafluoropropylenes and vinylidene fluoride-co-tetrafluoroethylene-co-hexafluoropropylenes are available, for example, Fluorel FX-9038.
The molecular weight of the uncured polymer is largely a matter of convenience, however, an excessively large or excessively small molecular weight would create problems, the nature of which are well known to those skilled in the art. In a preferred embodiment of the invention the uncured polymer has a number average molecular weight in the range of about 100,000 to 200,000.
In cases where it is intended that the fuser member be heated by an internal heater, it is desirable that outer layer have a relatively high thermal conductivity, so that the heat can be efficiently and quickly transmitted toward the outer surface of the fuser member that will contact the toner intended to be fused. (Depending upon relative thicknesses, it is generally even more desirable that the base cushion layer and any other intervening layers have a relatively high thermal conductivity. Suitable materials for the base cushion layer are discussed below.) The outer layer of the fuser member of the invention has a thermal conductivity in the range of about 0.15 to 0.40 BTU/hr·ft·°CF. This is comparable to previously known base cushion layer formulations, such as the above discussed EC4952.
Some fusing systems use a release oil, such as a PDMS oil, to prevent offset, that is, to aid the roll in releasing from the toner it contacts during the fusing operation. During use, the oil is continuously coated over the surface of the fuser member in contact with the toner image. The fuser member of the invention can be used with polydimethylsiloxane or mercapto functionalized polydimethylsiloxane release oils at normally used application rates or at reduced application rates, from about 0.5 mg/copy to 10 mg/copy (the copy is 8.5 by 11 inch 20 pound bond paper.
The outer layer of the fuser member of the invention is substantially resistant to release oil induced swelling. In a preferred embodiment of the invention, the change in size due to swelling is less than 0.1 to 1.0 percent. In an even more preferred embodiment of the invention, the change in size due to swelling is less than 0.01 to 0.1 percent.
The thicknesses of the base cushion and outer layers and the composition of the base cushion layer can be chosen so that the base cushion layer can provide the desired resilience to the fuser member, and the outer layer can flex to conform to that resilience. The thickness of the base cushion and outer layers will be chosen with consideration of the requirements of the particular application intended. Usually, the outer layer would be thinner than the base cushion layer. For example, base cushion layer thicknesses in the range from 0.6 to 5.0 mm have been found to be appropriate for various applications. In some embodiments of the present invention, the base cushion layer is about 2.5 mm thick, and the outer layer is from about 25 to 30 micrometers thick.
Suitable materials for the base cushion layer include any of a wide variety of materials previously used for base cushion layers, such as the condensation cured polydimethylsiloxane marketed as EC4952 by Emerson Cuming. An example of a condensation cured silicon rubber base cushion layer is GE 4044 marketed by General Electric of Waterford, N.Y. An example of an addition cured silicone rubber is Silastic J RTV marketed by Dow Corning applied over a silane primer DC-1200 also marketed by Dow Corning.
In a particular embodiment of the invention, the base cushion is resistant to cyclic stress induced deformation and hardening. Such materials when subjected to cyclic stress using an MER, as above discussed, exhibit changes in length and hardness (storage modulus) of less than about 20 percent. Examples of suitable materials are filled condensation-crosslinked PDMS elastomers disclosed in U.S. Pat. No. 5,269,740 (copper oxide filler), U.S. Pat. No. 5,292,606 (zinc oxide filler), U.S. Pat. No. 5,292,562 (chromium oxide filler), U.S. patent application Ser. No. 08/167,584 (tin oxide filler), U.S. patent application Ser. No. 08/159,013 (nickel oxide filler). These materials all show reasonable heat conductivities and much less change in hardness and creep than EC4952 or the PDMS elastomer with aluminum oxide filler. Additional suitable base cushions are disclosed in U.S. patent application Ser. No. 268,136, entitled "Zinc Oxide Filled Diphenylsiloxane-Dimethylsiloxane Fuser Roll for Fixing Toner to a Substrate", filed contemporaneously with this application, by John J. Fitzgerald et al; U.S. patent application Ser. No. 268,141, entitled "Tin Oxide Filled Diphenylsiloxane-Dimethylsiloxane Fuser Roll for Fixing Toner to a Substrate", filed contemporaneously with this application, by John J. Fitzgerald et al; U.S. patent application Ser. No. 268,131, entitled "Tin Oxide Filled Dimethylsiloxane-Fluoroalkylsiloxane Fuser Roll for Fixing Toner to a Substrate", filed contemporaneously with this application, by Wayne Thomas Ferrar et al. The patents and patent applications mentioned in this paragraph are hereby incorporated herein by reference.
The core of the fuser member is usually cylindrical in shape. It comprises any rigid metal or plastic substance. Metals are preferred when the fuser member is to be internally heated, because of their generally higher thermal conductivity. Suitable core materials include, e.g., aluminum, steel, various alloys, and polymeric materials such as thermoset resins, with or without fiber reinforcement. The core can be a support which has been conversion coated and primed with metal alkoxide primer in accordance with a U.S. patent application filed by Allen Kass, Oct. 21, 1993, entitled "FUSING MEMBER FOR ELECTROSTATOGRAPHIC REPRODUCING APPARATUS AND METHOD FOR PREPARING FUSING MEMBER"; the specification of which is hereby incorporated by reference herein.
The fuser member is mainly described herein in terms of embodiments in which the fuser member is a fuser roll having a core, a base cushion layer overlying the core, and an outer layer superimposed on the base cushion. The invention is not, however, limited to a roll, nor is the invention limited to a fusing member having a core bearing two layers: the base cushion layer and the outer layer. The fuser member of the invention can have a variety of outer configurations and layer arrangements known to those skilled in the art. For example, the base cushion layer could be eliminated or the outer layer descibed herein could be overlaid by one or more additional layers.
The invention is further illustrated by the following Examples and Comparative Examples.
A cylindrical stainless steel core was cleaned with dichloromethane and dried. The core was then primed with a uniform coat of a metal alkoxide type primer, Dow™ 1200 RTV Prime Coat primer, marketed by Dow Corning Corporation of Midland, Mich.; which contains: light aliphatic petroleum naptha (85 weight percent), tetra (2-methoxyethoxy)-silane (5 weight percent), tetrapropyl orthosilicate (5 weight percent), and tetrabutyl titanate (5 weight percent). Silastic™ J RTV room temperature vulcanizing silicone rubber, marketed by Dow Corning Corporation of Midland, Mich.; was then mixed with catalyst and injection molded onto the core and cured at 232°C C. for 2 hours under 75 tons/inch2 of pressure. The roller was then removed from the mold and baked in a convection oven with a temperature ramp increasing to 232°C C. substantially uniformly over 24 hours and then maintaining that temperature for an additional 24 hours. After air cooling, EC4952 marketed by Emerson Cumming Division of W. R. Grace and Co. of Conn. was blade coated directly onto the Silastic J layer, then cured for 12 hours at about 210°C C., followed by 48 hours at 218°C C. in a convection oven. After air cooling, the EC4952 was ground to a thickness of 20 mils. The cured EC4952 was corona discharged for 15 minutes at 750 watts and an outer layer was applied.
Fluorocarbon polymer was mixed as indicated in Table 1, as a 25 weight percent solids solution in a 1 to 1 mixture of methyl ethyl ketone and methyl isobutyl ketone. The resulting material was ring coated onto the cured EC4952 layer, air dried for 16 hours, baked with ramping for 4 hours to 205°C C. and then maintaining at 205°C C. for 12 hours. The Silastic J layer had a thickness of 380 mils. The resulting outer layer of fluorocarbon polymer had a thickness of 1 mil.
The storage modulus determination was done in accordance with the method of calculation described in Fitzgerald, et al., "The Effect of Cyclic Stress on the Physical Properties of a Poly(dimethylsiloxane) Elastomer", Polymer Engineering and Science, Vol. 32, No. 18 (September 1992), pp. 1350-1357. Six of the circular disks were stacked, one upon the other, weighed, and then placed in a test instrument called a Mechanical Energy Resolver (also referred to herein as an "MER"), commercially available from Instrumentors, Inc. Strongsville, Ohio, U.S.A. The instrument heated the stack to 218°C C. and imposed a static compressive force of 8 kg on the stack. The length of the stack under the initial compressive force was then measured, as was the initial hardness (expressed in terms of "Initial storage modulus"). The MER then imposed cyclic stress on the sample stack by sinusoidally varying the initial compressive force by 4 kg rms at a frequency of 30 Hz for 60 hours, while maintaining the 218°C C. temperature. After 60 hours, the final hardness ("Final storage modulus") and length of the six-disk stack under the static 8 kg compressive force were measured, as was the final weight of the sample stack. Results are presented in
A sample slab of fluorocarbon elastomer was prepared in substantially the same manner as in Example 1 except aluminum oxide was added to provide a volume concentration of 35 volume percent. A slab was prepared and circular disks (12 mm diameter) were cut from the slab. Thermal conductivity of the disks was measured in accordance with ASTM F433-77 and was found to be 0.24 BTU/hr·ft·°CF.
Substantially the same procedures were followed as in Example 1, except that the fluorocarbon polymer was changed as indicated in Table 1. Results are presented in
| TABLE 1 | |||
| Example or | |||
| Comparative | |||
| Example | Fluorocarbon | Additional filler | |
| Ex 1 | Viton A | 30 vol % aluminum oxide | |
| Ex 2 | FX-2530 | 30 vol % aluminum oxide | |
| Comp Ex 1 | Viton A | 30 vol % zinc oxide | |
| Comp Ex 2 | Viton A | 30 vol % tin oxide | |
| Comp Ex 3 | FX-2530 | 30 vol % zinc oxide | |
| Comp Ex 4 | FX-2530 | 30 vol % tin oxide | |
| Comp Ex 5 | Viton A | 35 vol % chromium oxide | |
| Comp Ex 6 | Viton A | 35 vol % copper oxide | |
| Comp Ex 7 | Viton A | 35 vol % titanium oxide | |
| Comp Ex 8 | Viton A | 35 vol % zirconium oxide | |
| Comp Ex 9 | Viton A | 35 vol % calcium oxide | |
| Comp Ex 10 | FX-2530 | 35 vol % calcium oxide | |
| Comp Ex 11 | FX-2530 | 35 vol % copper oxide | |
| Comp Ex 12 | FX-2530 | 35 vol % chromium oxide | |
| TABLE 1 | |||
| Example or | |||
| Comparative | |||
| Example | Fluorocarbon | Additional filler | |
| Ex 1 | Viton A | 30 vol % aluminum oxide | |
| Ex 2 | FX-2530 | 30 vol % aluminum oxide | |
| Comp Ex 1 | Viton A | 30 vol % zinc oxide | |
| Comp Ex 2 | Viton A | 30 vol % tin oxide | |
| Comp Ex 3 | FX-2530 | 30 vol % zinc oxide | |
| Comp Ex 4 | FX-2530 | 30 vol % tin oxide | |
| Comp Ex 5 | Viton A | 35 vol % chromium oxide | |
| Comp Ex 6 | Viton A | 35 vol % copper oxide | |
| Comp Ex 7 | Viton A | 35 vol % titanium oxide | |
| Comp Ex 8 | Viton A | 35 vol % zirconium oxide | |
| Comp Ex 9 | Viton A | 35 vol % calcium oxide | |
| Comp Ex 10 | FX-2530 | 35 vol % calcium oxide | |
| Comp Ex 11 | FX-2530 | 35 vol % copper oxide | |
| Comp Ex 12 | FX-2530 | 35 vol % chromium oxide | |
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it should be appreciated that variations and modifications can be effected within the scope of the invention.
Fitzgerald, John J., Chen, Jiann H., Staudenmayer, William J., Ferrar, Wayne T., Vreeland, II, William B., Roberts, Gary F.
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