Silanol containing photoconductors

Abstract

A photoconductor containing an optional supporting substrate, a photogenerating layer, and at least one silanol containing charge transport layer.

Description

COMPARATIVE EXAMPLE 1

An imaging member was prepared by providing a 0.02 micrometer thick titanium layer coated (the coater device) on a biaxially oriented polyethylene naphthalate substrate (KALEDEX™ 2000) having a thickness of 3.5 mils, and applying thereon, with a gravure applicator, a solution containing 50 grams of 3-amino-propyltriethoxysilane, 41.2 grams of water, 15 grams of acetic acid, 684.8 grams of denatured alcohol, and 200 grams of heptane. This layer was then dried for about 5 minutes at 135° C. in the forced air dryer of the coater. The resulting blocking layer had a dry thickness of 500 Angstroms. An adhesive layer was then prepared by applying a wet coating over the blocking layer using a gravure applicator, and which adhesive layer contains 0.2 percent by weight based on the total weight of the solution of the copolyester adhesive (ARDEL™ D100 available from Toyota Hsutsu Inc.) in a 60:30:10 volume ratio mixture of tetrahydrofuran/monochlorobenzene/ methylene chloride. The adhesive layer was then dried for about 5 minutes at 135° C. in the forced air dryer of the coater. The resulting adhesive layer had a dry thickness of 200 Angstroms.

A photogenerating layer dispersion was prepared by introducing 0.45 grams of the known polycarbonate LUPILON™ 200 (PCZ-200) or POLYCARBONATE Z™, weight average molecular weight of 20,000, available from Mitsubishi Gas Chemical Corporation, and 50 milliliters of tetrahydrofuran into a 4 ounce glass bottle. To this solution were added 2.4 grams of hydroxygallium phthalocyanine (Type V) and 300 grams of ⅛ inch (3.2 millimeters) diameter stainless steel shot. This mixture was then placed on a ball mill for 8 hours. Subsequently, 2.25 grams of PCZ-200 were dissolved in 46.1 grams of tetrahydrofuran, and added to the hydroxygallium phthalocyanine dispersion. This slurry was then placed on a shaker for 10 minutes. The resulting dispersion was, thereafter, applied to the above adhesive interface with a Bird applicator to form a photogenerating layer having a wet thickness of 0.25 mil. A strip about 10 millimeters wide along one edge of the substrate web bearing the blocking layer and the adhesive layer was deliberately left uncoated by any of the photogenerating layer material to facilitate adequate electrical contact by the ground strip layer that was applied later. The photogenerating layer was dried at 120° C. for 1 minute in a forced air oven to form a dry photogenerating layer having a thickness of 0.4 micrometer.

The resulting imaging member web was then overcoated with a two-layer charge transport layer. Specifically, the photogenerating layer was overcoated with a charge transport layer (the bottom layer) in contact with the photogenerating layer. The bottom layer of the charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 1:1 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, and MAKROLON® 5705, a known polycarbonate resin having a molecular weight average of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G. The resulting mixture was then dissolved in methylene chloride to form a solution containing 15 percent by weight solids. This solution was applied on the photogenerating layer to form the bottom layer coating that upon drying (120° C. for 1 minute) had a thickness of 14.5 microns. During this coating process, the humidity was equal to or less than 15 percent.

The bottom layer of the charge transport layer was then overcoated with a top layer. The charge transport layer solution of the top layer was prepared as described above for the bottom layer. This solution was applied on the bottom layer of the charge transport layer to form a coating that upon drying (120° C. for 1 minute) had a thickness of 14.5 microns. During this coating process, the humidity was equal to or less than 15 percent.

EXAMPLE I

An imaging member was prepared by repeating the process of Comparative Example 1 except that the top layer of the charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 1:1:0.1 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, MAKROLON® 5705, a polycarbonate resin having a weight average molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G., and phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.). The resulting mixture was dissolved in methylene chloride to form a solution containing 15 percent by weight solids.

EXAMPLE II

An imaging member was prepared by repeating the process of Comparative Example 1 except that the top layer of the charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 1:1:0.2 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, MAKROLON® 5705, a polycarbonate resin having a weight average molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G., and phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.). The resulting mixture was dissolved in methylene chloride to form a solution containing 15 percent by weight solids.

EXAMPLE III

An imaging member was prepared by repeating the process of Comparative Example 1 except that the top layer of the charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 1:1:0.4 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, MAKROLON® 5705, a polycarbonate resin having a weight average molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, and phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.). The resulting mixture was dissolved in methylene chloride to form a solution containing 15 percent by weight solids.

EXAMPLE IV

An imaging member is prepared as in Comparative Example 1 except that the top layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 1:1:0.2:0.1 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, MAKROLON® 5705, a polycarbonate resin having a molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, the silanol phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.), and the antioxidant IRGANOX) 1010, tetrakis methylene(3,5-di-tert-butyl-4-hydroxy hydrocinnamate), available from Ciba Specialty Chemical. The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids.

EXAMPLE V

An imaging member is prepared by repeating the process of Comparative Example 1 except that the bottom layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 1:1:0.4 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, MAKROLON® 5705, a polycarbonate resin having a weight average molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G., and the silanol phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.). The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids.

Electrical Property Testing

The above prepared photoreceptor devices (Comparative Example 1 and Examples I, II, and III) were tested in a scanner set to obtain photoinduced discharge cycles, sequenced at one charge-erase cycle followed by one charge-expose-erase cycle, wherein the light intensity was incrementally increased with cycling to produce a series of photoinduced discharge characteristic curves from which the photosensitivity and surface potentials at various exposure intensities are measured. Additional electrical characteristics were obtained by a series of charge-erase cycles with incrementing surface potential to generate several voltage versus charge density curves. The scanner was equipped with a scorotron set to a constant voltage charging at various surface potentials. The devices were tested at surface potentials of 500 with the exposure light intensity incrementally increased by means of regulating a series of neutral density filters; the exposure light source was a 780 nanometer light emitting diode. The xerographic simulation was completed in an environmentally controlled light tight chamber at ambient conditions (40 percent relative humidity and 22° C.). The devices were also cycled to 10,000 cycles electrically with charge-discharge-erase. Eight photoinduced discharge characteristic (PIDC) curves were generated, one for each of the above prepared photoconductors at both cycle=0 and cycle=10,000, and where V equals volt. The results are summarized in Table 1.

	TABLE 1
	V (3.5 ergs/cm2) (V)
	Cycle = 0	Cycle = 10,000
	Comparative Example 1	60	115
	Example I	33	53
	Example II	27	38
	Example III	18	24

In embodiments, there is disclosed a number of improved characteristics for the photoconductive members as determined by the generation of known PIDC curves, such as minimization or prevention of V_r cycle up by the physical doping of the silanol in the charge transport layer. More specifically, V (3.5 ergs/cm²) in Table 1 represents the surface potential of the device when exposure is 3.5 ergs/cm² (V), and is used to characterize the PIDC. Incorporation of the silanol into the charge transport layer reduces V (3.5 ergs/cm²) as shown and prevents photoconductor cycle up with extended cycling.

Scratch Resistance Testing

R_q, which represents the surface roughness, can be considered the root mean square roughness as the standard metric for the scratch resistance assessment with a scratch resistance of grade 1 representing poor scratch resistance, and a scratch resistance of grade 5 representing excellent scratch resistance as measured by a surface profile meter. More specifically, the scratch resistance is grade 1 when the R_q measurement is greater than 0.3 microns; grade 2 for R_q between 0.2 and 0.3 microns; grade 3 for R_q between 0.15 and 0.2 microns; grade 4 for R_q between 0.1 and 0.15 microns; and grade 5 being the best or excellent scratch resistance when R_q is less than 0.1 microns.

The above prepared four photoconductive belts (Comparative Example 1 and Examples I, II and III) were cut into strips of 1 inch in width by 12 inches in length, and were flexed in a tri-roller flexing system. Each belt was under a 1.1 lb/inch tension, and each roller was ⅛ inch in diameter. A polyurethane “spots blade” was placed in contact with each belt at an angle of between 5 and 15 degrees. Carrier beads of about 100 micrometers in size diameter were attached to the spots blade by the aid of double tape. These beads struck the surface of each of the belts as the photoconductor rotated in contact with the spots blade for 200 simulated imaging cycles. The surface morphology of each scratched area was then analyzed.

Incorporation of the above silanol into the charge transport layer improved scratch resistance by from about 30 percent to about 50 percent.

For example, after the scratch resistance test, the comparative imaging member with no silanol had an R_q value of 0.3 microns; the imaging members with the silanol had an R_q value of from 0.15 to 0.2 microns depending on loading of the silanol. Thus, a scratch resistance improvement of from about 30 percent to about 50 percent was realized with incorporation of the silanol into charge transport layers.

The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.

Claims

1. An imaging member comprising an optional supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and at least one silanol.

2. A photoconductor comprising an optional substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and at least one silanol, and wherein said silanol is selected from the group comprised of the following formulas/structures

3. A photoconductor in accordance with claim 2 wherein R and R′ are phenyl, methyl, vinyl, allyl, isobutyl, isooctyl, cyclopentyl, cyclohexyl, cyclohexenyl-3-ethyl, epoxycyclohexyl-4-ethyl, fluorinated alkyl, methacrylolpropyl, or norbornenylethyl.

4. A photoconductor in accordance with claim 2 wherein said silanol is selected from a group comprised of isobutyl-polyhedral oligomeric silsesquioxane cyclohexenyidimethylsilyldisilanol, cyclopentyl-polyhedral oligomeric silsesquioxane dimethylphenyidisilanol, cyclohexyl-polyhedral oligomeric silsesquioxane dimethylvinyldisilanol, cyclopentyl-polyhedral oligomeric silsesquioxane dimethylvinyldisilanol, isobutyl-polyhedral oligomeric silsesquioxane dimethylvinyldisilanol, cyclopentyl-polyhedral oligomeric silsesquioxane disilanol, isobutyl-polyhedral oligomeric silsesquioxane disilanol, isobutyl-polyhedral oligomeric silsesquioxane epoxycyclohexyldisilanol, cyclopentyl-polyhedral oligomeric silsesquioxane fluoro(3)disilanol, cyclopentyl-polyhedral oligomeric silsesquioxane fluoro(13)disilanol, isobutyl-polyhedral oligomeric silsesquioxane fluoro(13)disilanol, cyclohexyl-polyhedral oligomeric silsesquioxane methacryldisilanol, cyclopentyl-polyhedral oligomeric silsesquioxane methacryldisilanol, isobutyl-polyhedral oligomeric silsesquioxane methacryldisilanol, cyclohexyl-polyhedral oligomeric silsesquioxane monosilanol, cyclopentyl-polyhedral oligomeric silsesquioxane monosilanol, isobutyl-polyhedral oligomeric silsesquioxane monosilanol, cyclohexyl-polyhedral oligomeric silsesquioxane norbornenylethyldisilanol, cyclopentyl-polyhedral oligomeric silsesquioxane norbornenylethyldisilanol, isobutyl-polyhedral oligomeric silsesquioxane norbornenylethyidisilanol, cyclohexyl-polyhedral oligomeric silsesquioxane TMS disilanol, isobutyl-polyhedral oligomeric silsesquioxane TMS disilanol, cyclohexyl-polyhedral oligomeric silsesquioxane trisilanol, cyclopentyl-polyhedral oligomeric silsesquioxane trisilanol, isobutyl-polyhedral oligomeric silsesquioxane trisilanol, isooctyl-polyhedral oligomeric silsesquioxane trisilanol, and phenyl-polyhedral oligomeric silsesquioxane trisilanol.

5. A photoconductor in accordance with claim 2 wherein said silanol is selected from at least one of the group comprised of dimethyl(thien-2-yl)silanol, tris(isopropoxy)silanol, tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol, tris(o-tolyl)silanol, tris(1-naphthyl)silanol, tris(2,4,6-trimethylphenyl)silanol, tris(2-methoxyphenyl)silanol, tris(4-(dimethylamino)phenyl)silanol, tris(4-biphenylyl)silanol, tris(trimethylsilyl)silanol, and dicyclohexyltetrasilanol.

6. A photoconductor in accordance with claim 2 wherein said charge transport component is comprised of aryl amine molecules, and which aryl amines are of the formula

7. A photoconductor in accordance with claim 6 wherein said alkyl and said alkoxy each contains from about 1 to about 12 carbon atoms, and said aryl contains from about 6 to about 36 carbon atoms; and wherein said R-and R′ alkyl and alkoxy contain from 1 to about 12 carbon atoms, and said aryl contains from 6 to about 36 carbon atoms; and wherein the photoconductor contains a supporting substrate.

8. A photoconductor in accordance with claim 6 wherein said aryl amine is N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine.

9. A photoconductor in accordance with claim 2 wherein said charge transport component is comprised of aryl amine molecules, and which aryl amines are of the formula

10. A photoconductor in accordance with claim 9 wherein alkyl and alkoxy each contains from about 1 to about 12 carbon atoms, and aryl contains from about 6 to about 36 carbon atoms.

11. A photoconductor in accordance with claim 9 wherein said aryl amine is selected from at least one of the group consisting of N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-m-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-o-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2-ethyl-6-methylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-diphenyl-N,N′-bis(3-chlorophenyl)-[p-terphenyl]-4,4″-diamine, and wherein said photoconductor further comprises a supporting substrate.

12. A photoconductor in accordance with claim 2 wherein said silanol is present in from 1 to about 4 transport layers in an amount in each layer of from about 0.1 to about 40 weight percent, wherein said charge transport contains hole transport molecules and a resin binder, and wherein said photogenerating layer contains a photogenerating pigment and a resin binder.

13. A photoconductor in accordance with claim 2 further including in at least one of said charge transport layers an antioxidant optionally comprised of hindered phenolics and hindered amines.

14. A photoconductor in accordance with claim 2 wherein said photogenerating layer is comprised of a photogenerating pigment or photogenerating pigments, and said photoconductor further includes a supporting substrate.

15. A photoconductor in accordance with claim 14 wherein said photogenerating pigment is comprised of at least one of a metal phthalocyanine, a metal free phthalocyanine, a titanyl phthalocyanine, a halogallium phthalocyanine, a perylene, or mixtures thereof.

16. A photoconductor in accordance with claim 14 wherein said photogenerating pigment is comprised of a titanyl phthalocyanine.

17. A photoconductor in accordance with claim 14 wherein said photogenerating pigment is comprised of chlorogallium phthalocyanine.

18. A photoconductor in accordance with claim 14 wherein said photogenerating pigment is comprised of hydroxygallium phthalocyanine.

19. A photoconductor in accordance with claim 2 further including a hole blocking layer, and an adhesive layer, and wherein said substrate is present.

20. A photoconductor in accordance with claim 2 wherein said photoconductor is a flexible belt, and said silanol possesses a weight average molecular weight Mw of from about 700 to about 2,000.

21. A photoconductor in accordance with claim 2 wherein said at least one charge transport layer is from 1 to about 7 layers, and said substrate is present.

22. A photoconductor in accordance with claim 2 wherein said at least one charge transport layer is from 1 to about 3 layers.

23. A photoconductor in accordance with claim 2 wherein said at least one charge transport layer is comprised of a top charge transport layer and a bottom charge transport layer, and wherein said top layer is in contact with said bottom layer and said bottom layer is in contact with said photogenerating layer, and wherein said photocoductor includes a supporting substrate.

24. A photoconductor in accordance with claim 23 wherein said top layer is comprised of a hole transport component, a resin binder, an optional antioxidant, and said silanol; and said bottom layer is comprised of at least one charge transport component, a resin binder, and an optional antioxidant.

25. A photoconductor in accordance with claim 23 wherein said top layer is comprised of a hole transport component, a resin binder, and an antioxidant; and said bottom layer is comprised of at least one charge transport component, a resin binder, an antioxidant, and said silanol.

26. A photoconductor in accordance with claim 2 wherein said silanol is present in an amount of from about 0.1 to about 40 weight percent.

27. A photoconductor in accordance with claim 2 wherein said silanol is present in an amount of from about 1 to about 30 weight percent.

28. A photoconductor comprised in sequence of a substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and at least one silanol, wherein said silanol is selected from the group comprised of the following formulas/structures

29. A photoconductor in accordance with claim 28 wherein said silanol is present in an amount of from 1 to about 30 weight percent, said hydrocarbon is alkyl and alkoxy each containing from 1 to about 12 carbon atoms, and aryl containing from 6 to about 36 carbon atoms.

30. A photoconductor in accordance with claim 28 wherein at least one of said charge transport layers contains a resin binder; said photogenerating layer is situated between said at least one charge transport and said substrate, and which layer contains a resin binder; said silanol is present in an amount of from about 1 to about 30 weight percent; and wherein said at least one is from 1 to about 4.

31. A photoconductor in accordance with claim 28 wherein said R and R′ hydrocarbon are independently alkyl, alkoxy, aryl, or substituted derivatives thereof, or mixtures thereof wherein said silanol is present in an amount of from about 1 to about 10 weight percent, and wherein said at least one is from 1 to about 5.

32. A photoconductor in accordance with claim 2 wherein said at least one is at least two, and wherein one of said charge transport layers is free of said silanol.