U.S. patent application number 12/898782 was filed with the patent office on 2012-04-12 for sulfonamide-doped undercoat for imaging device.
This patent application is currently assigned to XEROX CORPORATION. Invention is credited to Nancy L. Belknap, Helen R. Cherniack, Yuhua Tong, Jin Wu.
Application Number | 20120088872 12/898782 |
Document ID | / |
Family ID | 45925630 |
Filed Date | 2012-04-12 |
United States Patent
Application |
20120088872 |
Kind Code |
A1 |
Tong; Yuhua ; et
al. |
April 12, 2012 |
Sulfonamide-doped undercoat for imaging device
Abstract
A photoreceptor undercoat for an electrostatographic imaging
device containing a film-forming material, such as, a phenolic
resin; a metal oxide, such as, a titanium oxide; and a sulfonamide,
including that such sulfonamide facilitates removal of the
undercoat from the photoreceptor substrate.
Inventors: |
Tong; Yuhua; (Webster,
NY) ; Wu; Jin; (Webster, NY) ; Belknap; Nancy
L.; (Rochester, NY) ; Cherniack; Helen R.;
(Rochester, NY) |
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
45925630 |
Appl. No.: |
12/898782 |
Filed: |
October 6, 2010 |
Current U.S.
Class: |
524/169 ;
106/287.23 |
Current CPC
Class: |
C08K 3/22 20130101; G03G
2215/00957 20130101; C08K 5/435 20130101; B08B 3/08 20130101; G03G
5/142 20130101; Y02P 20/582 20151101; G03G 5/144 20130101; G03G
5/102 20130101 |
Class at
Publication: |
524/169 ;
106/287.23 |
International
Class: |
G03G 15/00 20060101
G03G015/00; C09D 5/00 20060101 C09D005/00; C08K 5/435 20060101
C08K005/435; G03G 5/00 20060101 G03G005/00 |
Claims
1. A photoreceptor undercoat comprising a film-forming material, a
metal oxide and a sulfonamide, wherein said sulfonamide is N-butyl
benzene sulfonamide or N-(2-hydroxylpropyl) benzene
sulfonamide.
2. The undercoat of claim 1, wherein said metal oxide comprises
titanium oxide.
3. The undercoat of claim 1, wherein said sulfonamide is N-butyl
benzene sulfonamide.
4. The undercoat of claim 1, wherein the undercoat is readily
removed from a substrate by a buffer comprising an aprotic polar
solvent and a weak organic acid as compared to an undercoat without
said sulfonamide.
5. A photoreceptor comprising the undercoat of claim 1.
6. An imaging device component comprising the photoreceptor of
claim 5.
7. An imaging device comprising the component of claim 6.
8. A photoreceptor undercoat comprising a phenolic resin, a metal
oxide and a sulfonamide, wherein said sulfonamide is N-butyl
benzene sulfonamide or N-(2-hydroxylpropyl) benzene
sulfonamide.
9. The undercoat of claim 8, wherein the undercoat is readily
removed from a substrate by a buffer comprising an aprotic polar
solvent and a weak organic acid as compared to an undercoat without
said sulfonamide.
10. The undercoat of claim 8, wherein said metal oxide comprises
titanium oxide.
11. The undercoat of claim 8, wherein said metal oxide comprises
from about 20 wt % to about 80 wt % of said undercoat.
12. A photoreceptor comprising the undercoat of claim 8.
13. An imaging device component comprising the photoreceptor of
claim 12.
14. An imaging device comprising the component of claim 13.
15. The imaging device of claim 14, comprising electrical
properties, ghosting levels or coating layer adherence to a
substrate, comparable to that of an imaging device comprising a
photoreceptor comprising an undercoat lacking a sulfonamide.
16. The imaging device of claim 15, wherein said undercoat is
readily removed by striping with an aprotic polar buffer comprising
a weak acid at atmospheric pressure and/or at a temperature less
than about 100.degree. C. as compared to an undercoat without said
sulfonamide.
17. A photoreceptor undercoat comprising a film forming material
selected from the group consisting of a casein, a phenolic resin, a
polyol, an aminoplast resin, a polyvinyl alcohol, a nitrocellulose,
an ethylene-acrylic acid copolymer, a polyamide, a polyurethane, a
gelatin, and combinations thereof; a titanium oxide; and a
sulfonamide, wherein the sulfonamide is N butyl benzene
sulfonamide, or N-(2-hydroxylpropyl) benzene sulfonamide, and
wherein the undercoat is readily removed from a substrate by a
buffer comprising an aprotic organic polar solvent and a weak
organic acid as compared to an undercoat without said
sulfonamide.
18. A photoreceptor comprising the undercoat of claim 17.
19. An imaging device component comprising the photoreceptor of
claim 18.
20. An imaging device comprising the component of claim 19.
Description
FIELD
[0001] A novel undercoat for an electrostatographic imaging device
component is provided. The imaging device can be used in
electrophotographic or electrostatographic devices, such as,
xerographic devices.
BACKGROUND
[0002] Reclaiming, recycling or reconditioning of devices heavily
used; of components of devices; or of devices containing rare or
toxic materials can be environmentally sound, economically
advantageous and/or required.
[0003] In the electrostatographic imaging arts, the photoactive
portions of most photoreceptors are composed of organic materials.
The rigor and repetitive use command durability of the
photoreceptors. Thus, reconditioning or reclaiming organic
photoreceptors requires costly materials, and inefficient and/or
time consuming methods.
[0004] Hence, a problem to be solved is developing photoreceptors
which are durable and yet more amenable to reclamation by the ready
deconstruction of the various components and materials comprising
organic photoreceptors. That problem was solved by developing an
undercoat that is easily removed from the substrate of a
photoreceptor.
SUMMARY
[0005] According to aspects disclosed herein, there is provided a
photoreceptor undercoat composition comprising a film-forming
material, such as, a phenolic resin; a metal oxide, such as, a
titanium oxide; and a sulfonamide.
[0006] One disclosed feature of the embodiments is a photoreceptor
comprising an undercoat comprising a film-forming material, such
as, a phenolic resin; a metal oxide, such as, a titanium oxide; and
a sulfonamide.
[0007] Another disclosed embodiment is an imaging or printing
device comprising a photoreceptor comprising an undercoat
comprising a film-forming material, such as, a phenolic resin; a
metal oxide, such as, a titanium oxide; and a sulfonamide.
DETAILED DESCRIPTION
[0008] As used herein, the term, "electrostatographic," or
grammatic versions thereof, is used interchangeably with the terms,
"electrophotographic" and "xerographic." The terms, "charge
blocking layer" and "blocking layer," are used interchangeably with
the terms, "undercoat layer" or "undercoat," or grammatic versions
thereof. "Photoreceptor," is used interchangeably with,
"photoconductor," "imaging member" or "imaging component," or
grammatic versions thereof.
[0009] For the purposes of the instant application, "about," is
meant to indicate a deviation of 20% or less of a stated value or a
mean value.
[0010] In electrostatographic reproducing or imaging devices,
including, for example, a digital copier, an image-on-image copier,
a contact electrostatic printing device, a bookmarking device, a
facsimile device, a printer, a multifunction device, a scanning
device and any other device, a printed output is provided, whether
black and white or color, or an image of an original is recorded in
the form of an electrostatic latent image on an imaging device
component, such as, a photoreceptor, which may be present as an
integral component of an imaging device or as a replaceable
component or module of an imaging device, and that latent image is
rendered visible using electroscopic, finely divided, colored or
pigmented particles, or toner. The imaging device component or
photoreceptor can be used in electrophotographic (xerographic)
imaging processes and devices, for example, as a flexible belt or
in a rigid drum configuration. Other components may include a
flexible intermediate image transfer belt, which can be seamless or
seamed.
[0011] The imaging device component, the photoreceptor, generally
comprises one or more functional layers. Certain photoreceptors
include a photoconductive layer or layers formed on an electrically
conductive substrate or surface. The photoconductive layer is an
insulator in the dark so that electric charge is retained on the
surface thereof, which charge is dissipated on exposure to light.
In some embodiments of interest, a photoreceptor includes an
undercoat layer comprising a sulfonamide.
[0012] One type of composite photoconductive layer used in
xerography is illustrated in U.S. Pat. No. 4,265,990 which
describes an imaging device component having at least two
electrically operative layers, a photoconductive layer which
photogenerates holes and injects the photogenerated holes into a
charge transport layer (CTL). The photoreceptors can carry a
uniform negative or positive electrostatic charge to generate an
image which is visualized with finely divided electroscopic colored
or pigmented particles.
[0013] Embodiments of the present imaging device component or
photoreceptor can be used in an electrophotographic image forming
device or printing device. Hence, the imaging device component or
photoreceptor is electrostatically charged and then is exposed to a
pattern of activating electromagnetic radiation, such as light,
which dissipates the charge in the illuminated areas of the imaging
device component while leaving behind an electrostatic latent image
in the non-illuminated areas. The electrostatic latent image then
is developed at one or more developing stations to form a visible
image, for example, by depositing finely divided electroscopic
colored, dyed or pigmented particles, or toner, for example, from a
developer composition, on the surface of the imaging component. The
resulting visible image on the photoreceptor is transferred to a
suitable receiving member, such as a paper. Alternatively, the
developed image can be transferred to an intermediate transfer
device, such as a belt or a drum, and the image then is transferred
to a receiving member, such as a paper, or various other receiving
members or substrates, such as, a cloth, a polymer, a plastic, a
metal and so on, which can be presented in any of a variety of
forms, such as a flat surface, a smooth surface, a textured
surface, a sheet or a curved surface. The transferred colored
particles are fixed or fused to the receiving member by any of a
variety of means, such as, by exposure to elevated temperature
and/or pressure.
[0014] Thus, a photoreceptor can include a support or substrate;
which may comprise a conductive surface or a conductive layer or
layers (which may be referred to herein as a ground plane layer) on
an inert support; an undercoat; a charge generating layer (CGL);
and a CTL. Other optional functional layers that can be included in
a photoreceptor include a hole blocking layer; an adhesive
interface layer; an overcoat or protective layer; a ground strip;
and an anti-curl back coating layer. It will be appreciated that
one or more of the layers may be combined into a single layer.
The Substrate
[0015] The imaging device component substrate (or support) may be
opaque or substantially transparent, and may comprise any suitable
organic or inorganic material having the requisite mechanical
properties. The entire substrate can comprise an electrically
conductive material, or an electrically conductive material can be
a coating on an inert substrate. Any suitable electrically
conductive material can be employed, such as, copper, brass,
nickel, zinc, chromium, stainless steel, conductive plastics and
rubbers, aluminum, semitransparent aluminum, steel, cadmium,
silver, gold, indium, tin, zirconium, niobium, tantalum, vanadium,
hafnium, titanium, tungsten, molybdenum and so on; or a paper, a
plastic, a resin, a polymer and the like rendered conductive by the
inclusion of a suitable conductive material therein; metal oxides,
including tin oxide and indium tin oxide; and the like. The
conductive material can comprise a single of the above-mentioned
materials, such as, a single metallic compound, or a plurality of
materials and/or a plurality of layers of different components,
such as, a metal or an oxide, plural metals and so on.
[0016] The substrate can be an insulating material including
inorganic or organic polymeric materials, such as a commercially
available biaxially oriented polyethylene terephthalate, a
commercially available polyethylene naphthalate and so on, with a
ground plane layer comprising a conductive coating comprising one
or more of the materials provided hereinabove, including a titanium
or a titanium/zirconium coating, or a layer of an organic or
inorganic material having a semiconductive surface layer, such as
indium tin oxide, aluminum, titanium and the like. Thus, a
substrate can be a plastic, a resin, a polymer and so on, such as a
polycarbonate, a polyamide, a polyester, a polypropylene, a
polyurethane, a polyethylene and so on.
[0017] The substrate may have a number of many different
configurations, such as, for example, a plate, a sheet, a film, a
cylinder, a drum, a scroll, a flexible belt, which may be seamed or
seamless, and the like.
[0018] The thickness of the substrate can depend on any of a number
of factors, including flexibility, mechanical performance and
economic considerations. The thickness of the substrate may range
from about 25 .mu.m to about 3 mm. In embodiments of a flexible
imaging belt, the thickness of a substrate can be from about 50
.mu.m to about 200 .mu.m for flexibility and to minimize induced
imaging device component surface bending stress when a imaging
device component belt is cycled around small diameter rollers, for
example, 19 mm diameter rollers, in a machine belt support
module.
[0019] Generally, a substrate is not soluble in any of the solvents
used in the coating layer solutions, can be optically transparent
or semi-transparent, and can be thermally stable up to a
temperature of about 150.degree. C. or more.
The Conductive Layer
[0020] When a conductive ground plane layer is present, the layer
may vary in thickness depending on the optical transparency and
flexibility desired for the electrophotographic imaging device
component. When an imaging flexible belt is used, the thickness of
the conductive layer on the substrate, for example, a titanium
and/or a zirconium conductive layer produced by sputtering,
typically ranges from about 2 nm to about 75 nm in thickness to
allow adequate light transmission for proper back erase. In other
embodiments, a conductive layer can be from about 10 nm to about 20
nm in thickness for a combination of electrical conductivity,
flexibility and light transmission. For rear erase exposure, a
conductive layer light transparency of at least about 15% can be
used. The conductive layer may be an electrically conductive metal
layer which may be formed, for example, on the substrate by any
suitable coating technique, such as a vacuum depositing, dipping or
sputtering and so on as taught herein or as known in the art, and
the coating dried on the substrate using methods taught herein or
known in the art. Typical metals suitable for use in a conductive
layer include aluminum, zirconium, niobium, tantalum, vanadium,
hafnium, titanium, nickel, stainless steel, chromium, tungsten,
molybdenum, combinations thereof and the like. The conductive layer
need not be limited to metals. Hence, other examples of conductive
layers may be combinations of materials such as conductive indium
tin oxide as a transparent layer for light having a wavelength
between about 4000 .ANG. and about 9000 .ANG. or a conductive
carbon black dispersed in a plastic binder as an opaque conductive
layer.
The Hole Blocking Layer
[0021] An optional hole blocking layer may be applied, for example,
to the undercoat. Any suitable positive charge (hole) blocking
layer capable of forming an effective barrier to the injection of
holes from the adjacent conductive layer or substrate to the
photoconductive layer(s) or CGL may be used. The charge (hole)
blocking layer may include polymers, such as, a polyvinyl butyral,
epoxy resins, polyesters, polysiloxanes, polyamides, polyurethanes,
methacrylates, such as hydroxyethyl methacrylate (HEMA),
hydroxylpropyl celluloses, polyphosphazines and the like, or may
comprise nitrogen-containing siloxanes or silanes, or
nitrogen-containing titanium or zirconium compounds, such as,
titanate and zirconate. The hole blocking layer may have a
thickness of from about 0.2 .mu.m to about 10 .mu.m, depending on
the type of material chosen as a design choice. Typical hole
blocking layer materials include, for example, trimethoxysilyl
propylene diamine, hydrolyzed trimethoxysilyl propyl ethylene
diamine, N-.beta.-(aminoethyl)-.gamma.-aminopropyl trimethoxy
silane, isopropyl 4-aminobenzene sulfonyl di(dodecylbenzene
sulfonyl) titanate, isopropyl di(4-aminobenzoyl)isostearoyl
titanate, isopropyl tri(N-ethylaminoethylamino)titanate, isopropyl
trianthranil titanate, isopropyl
tri(N,N-dimethylethylamino)titanate, titanium-4-amino benzene
sulfonate oxyacetate, titanium 4-aminobenzoate isostearate
oxyacetate, (.gamma.-aminobutyl)methyl diethoxysilane,
(.gamma.-aminopropyl)methyl diethoxysilane and combinations
thereof, as disclosed, for example, in U.S. Pat. Nos. 4,338,387;
4,286,033; 4,988.597; 5,244,762; and 4,291,110, each incorporated
herein by reference in entirety.
[0022] The blocking layer may be applied by any suitable
conventional technique, such as, spraying, dip coating, draw bar
coating, gravure coating, silk screening, air knife coating,
reverse roll coating, vacuum deposition, chemical treatment and the
like. For convenience in obtaining thin layers, the blocking layer
may be applied in the form of a dilute solution, with the solvent
being removed after deposition of the coating by conventional
techniques, such as, vacuum, heating and the like. A weight ratio
of blocking layer material and solvent of from about 0.05:100 to
about 5:100 can be used for spray coating. Such deposition and
forming methods for forming layers can be used for making any of
the herein described layers.
The Adhesive Interface Layer
[0023] An optional adhesive interface layer may be employed. An
interface layer may be situated, for example, intermediate between
the hole blocking layer and the CGL. The interface layer may
include a polyurethane, a polyester and so on. An example of a
polyester includes a polyarylate, a polyvinyl butyral and the
like.
[0024] Any suitable solvent or solvent mixture may be employed to
form an adhesive interface layer coating solution. Typical solvents
include tetrahydrofuran, toluene, monochlorobenzene, methylene
chloride, cyclohexanone and the like, as well as mixtures thereof.
Any suitable and conventional technique may be used to mix and
thereafter to apply the adhesive interface layer coating mixture to
the photoreceptor under construction as taught herein or as known
in the art. Typical application techniques include spraying, dip
coating, roll coating, wire wound rod coating and the like. Setting
of the deposited wet coating may be accomplished by any suitable
conventional process, such as oven drying, infrared drying, air
drying and the like.
[0025] The adhesive interface layer may have a thickness of from
about 0.01 .mu.m to about 900 .mu.m after drying. In certain
embodiments, the dried thickness is from about 0.03 .mu.m to about
1 .mu.m.
The Charge Generating Layer
[0026] The CGL can comprise any suitable charge generating binder
or film-forming material including a charge
generating/photoconductive material suspended or dissolved therein,
which may be in the form of particles and dispersed in a
film-forming material or binder, such as an electrically inactive
resin. Examples of charge generating materials include, for
example, inorganic photoconductive materials, such as, azo
materials, such as, certain dyes, such as, Sudan Red and Diane
Blue, quinone pigments, cyanine pigments and so on, amorphous
selenium, trigonal selenium and selenium alloys, such as,
selenium-tellurium, selenium-tellurium-arsenic, selenium arsenide
and mixtures thereof, germanium and organic photoconductive
materials, including various phthalocyanine pigments, such as, the
X form of metal-free phthalocyanine, metal phthalocyanines, such
as, vanadyl phthalocyanine and copper phthalocyanine,
hydroxygallium phthalocyanines, chlorogallium phthalocyanines,
titanyl phthalocyanines, quinacridones, dibromo anthanthrone
pigments, benzimidazole perylene, substituted 2,4-diaminotriazines,
polynuclear aromatic quinones and the like dispersed in a
film-forming material, such as, a polymer, or a binder. Selenium,
selenium alloy and the like and mixtures thereof may be formed as a
homogeneous CGL. Benzimidazole perylene compositions are described,
for example, in U.S. Pat. No. 4,587,189, the entire disclosure
thereof being incorporated herein by reference. Multi-charge
generating layer compositions may be utilized where a
photoconductive layer enhances or reduces the properties of the
CGL. The charge generating materials can be sensitive to activating
radiation having a wavelength from about 400 nm to about 900 nm
during the imagewise radiation exposure step forming an
electrostatic latent image. For example, hydroxygallium
phthalocyanine absorbs light of a wavelength of from about 370 nm
to about 950 nm, as disclosed, for example, in U.S. Pat. No.
5,756,245.
[0027] Any suitable film-forming material may be employed in a CGL,
including those described, for example, in U.S. Pat. No. 3,121,006,
the entire disclosure thereof being incorporated herein by
reference. Typical film-forming materials include thermoplastic and
thermosetting resins, such as, a polycarbonate, a polyester, a
polyamide, a polyurethane, a polystyrene, a polyarylether, a
polyarylsulfone, a polybutadiene, a polysulfone, a
polyethersulfone, a polyethylene, a polypropylene, a polyimide, a
polymethylpentene, a polyphenylenesulfide, a polyvinyl butyral, a
polyvinyl acetate, a polysiloxane, a polyacrylate, a
polyvinylacetal, an amino resin, a phenyleneoxide resin, a
terephthalic acid resin, an epoxy resin, a phenolic resin, an
acrylonitrile copolymer, a polyvinylchloride, a vinylchloride, a
vinyl acetate copolymer, an acrylate copolymer, an alkyd resin, a
cellulosic film former, a poly(amideimide), a styrene-butadiene
copolymer, a vinylidenechloride/vinylchloride copolymer, a
vinylacetate/vinylidene chloride copolymer, a styrene-alkyd resin
and the like. Another film-forming material is PCZ-400
(poly(4,4'-dihydroxy-diphenyl-1-1-cyclohexane) with a
viscosity-molecular weight of about 40,000. A copolymer can be a
block or a graft, random or alternating, and so on.
[0028] The charge generating material can be present in the
film-forming material or binder composition in various amounts.
Generally, from about 5% by volume or weight to about 90% by volume
or weight of the charge generating material is dispersed in about
10% by volume or weight to about 95% by volume or weight of the
film-forming material or binder, or from about 20% by volume or
weight to about 60% by volume or weight of the charge generating
material is dispersed in about 40% by volume to about 80% by volume
of the film-forming material or binder composition.
[0029] The CGL containing the charge generating material and the
binder or film-forming material generally ranges in thickness from
about 0.1 .mu.m to about 5 .mu.m, for example, or from about 0.3
.mu.m to about 3 .mu.m when dry. The CGL thickness can be related
to film or binder content, higher film or binder content
compositions generally employ thicker layers for charge
generation.
[0030] In some embodiments, the CGL may comprise a charge transport
molecule or component, as discussed below in regard to the CTL. The
charge transport molecule may be present in some embodiments in an
amount from about 1% to about 60% by weight of the total weight of
the CGL.
The Charge Transport Layer
[0031] The CTL generally is superior or exterior to the CGL and may
include any suitable film-forming material, such as, a transparent
organic polymer or non-polymeric material capable of supporting the
injection of photogenerated holes or electrons from the CGL and
capable of allowing the transport of the holes/electrons through
the CTL to selectively discharge the charge on the surface of the
imaging device component. In one embodiment, the CTL not only
serves to transport holes, but also to protect the CGL from
abrasion or chemical attack and may therefore extend the service
life of the imaging device component. The CTL can be a
substantially non-photoconductive material, but one which supports
the injection of photogenerated holes from the CGL. The CTL
normally is transparent in a wavelength region in which the
electrophotographic imaging device component is to be used when
exposure is effected therethrough to ensure that most of the
incident radiation is utilized by the underlying CGL. Thus, the CTL
exhibits optical transparency with negligible light absorption and
negligible charge generation when exposed to a wavelength of light
useful in xerography, e.g., from about 400 nm to about 900 nm. In
the case when the imaging device component is prepared with
transparent materials, imagewise exposure or erase may be
accomplished through the substrate with all light passing through
the back side of the substrate. In that case, the materials of the
CTL need not transmit light in the wavelength region of use if the
CGL is sandwiched between the substrate and the CTL.
[0032] The CTL may include any suitable charge transport molecule
or activating compound useful as an additive molecularly dispersed
in an electrically inactive polymeric film-forming material to form
a solid solution and thereby making the material electrically
active. The charge transport molecule may be added to a
film-forming polymeric material which is otherwise incapable of
supporting the injection of photogenerated holes from the charge
generation material and incapable of allowing the transport of the
holes therethrough. The charge transport molecule typically
comprises small molecules of an organic compound which cooperate to
transport charge between molecules and ultimately to the surface of
the CTL, for example, see U.S. Pat. Nos. 7,759,032 and
7,704,658.
[0033] For example,
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4' diamine
can be used as a charge transport molecule. Other charge transport
molecules include pyrazolines, diamines, hydrazones, oxadiazoles,
stilbenes, carbazoles, oxazoles, triazoles, imidazoles,
imidazolones, imidazolidines, bisimidazolidines, styryls,
oxazolones, benzimidazoles, quinalolines, benzofurans, acridines,
phenazines, aminostilbenes, aromatic polyamines, such as aryl
diamines and aryl triamines, such as, aromatic diamines, including,
N,N'-diphenyl-N,N'-bis(alkylphenyl)-1,1'-biphenyl-4,4-diamines;
N,N'-diphenyl-N,N'-bis[3-methylphenyl]-[1,1'-biphenyl]-4,4'-diamines;
N,N'-diphenyl-N,N'-bis(chlorophenyl)-1,1'-biphenyl-4,4'-diamines;
N,N'-bis-(4-methylphenyl)-N,N'-bis(4-ethylphenyl)-1,1'-3,3'-dimethylbiphe-
nyl)-4,4'-diamines; N,N'-bis-(3,4-dimethylphenyl)-4,4'-biphenyl
amines; and combinations thereof. Other suitable charge transport
molecules include pyrazolines, such as,
1-[lepidyl-(2)]-3-(p-diethylaminophenyl)-5-(p-diethylaminophenyl)pyrazoli-
ne, as described, for example, in U.S. Pat. Nos. 4,315,982,
4,278,746, 3,837,851, and 6,214,514; substituted fluorene charge
transport molecules, such as,
9-(4'-dimethylaminobenzylidene)fluorene, as described in U.S. Pat.
Nos. 4,245,021 and 6,214,514; oxadiazole transport molecules, such
as 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole, pyrazolines,
imidazoles and triazoles, as described, for example, in U.S. Pat.
No. 3,895,944; hydrazones, such as p-diethylaminobenzaldehyde
(diphenylhydrazone), as described, for example, in U.S. Pat. Nos.
4,150,987 4,256,821, 4,297,426, 4,338,388, 4,385,106, 4,387,147,
4,399,207, 4,399,208, and 6,124,514; and tri-substituted methanes,
such as, alkyl-bis(N,N-dialkylaminoaryl)methanes, as described, for
example, in U.S. Pat. No. 3,820,989. The disclosure of each of
those patents is incorporated herein by reference in entirety.
[0034] The charge transport molecule may be present in some
embodiments from about 1% to about 60% by weight of the total
weight of the CTL or in other embodiments in an amount from about
10% to about 60% by weight of the total weight of the CTL.
[0035] Any suitable electrically inactive film-forming material or
binder may be used to form the CTL. Typical inactive film-forming
materials or binders include, a polycarbonate resin, a polystyrene,
a polyester, a polyarylate, a polyacrylate, a polyether, a
polysulfone and the like. Molecular weights can vary, for example,
from about 20,000 to about 150,000. Examples of film-forming
materials or binders include a polycarbonate, such as,
poly(4,4'-isopropylidene-diphenylene)carbonate (also referred to as
bisphenol-A-polycarbonate or PCA),
poly(4,4'-cyclohexylidine-diphenylene) carbonate (referred to as
bisphenol-Z-polycarbonate or PCZ),
poly(4,4'-isopropylidene-3,3'-dimethyl-diphenyl)carbonate (also
referred to as bisphenol-C-polycarbonate or PCC) and the like and
mixtures thereof.
[0036] Any suitable and conventional technique may be used to mix
and thereafter to apply the CTL coating mixture to the
photoreceptor under construction. Typical application techniques
include spraying, dip coating, roll coating, wire wound rod coating
and the like. Drying of the deposited coating may be obtained by
any suitable conventional technique such as oven drying, infrared
drying, air drying and the like.
[0037] Crosslinking agents can be used to promote polymerization of
the polymer or film-forming material of the CTL. Examples of
suitable crosslinking agents include an acrylated polystyrene, a
methacrylated polystyrene, an ethylene glycol dimethacrylate, a
bisphenol A glycerolate dimethacrylate, a
(dimethylvinylsilyloxy)heptacyclopentyltricycloheptasiloxanediol
and the like and mixtures thereof. The crosslinking agent can be
used in an amount of from about 1% to about 20%, or from about 5%
to about 10%, or from about 6% to about 9% by weight of total
polymer or film-forming material content.
[0038] The CTL can be an insulator to the extent that the
electrostatic charge placed on the CTL is not conducted in the
absence of illumination at a rate sufficient to prevent formation
and retention of an electrostatic latent image thereon. In general,
the ratio of the thickness of the CTL to the CGL is from about 2:1
to about 200:1 and in some instances as great as about 400:1.
[0039] The CTL can contain variable amounts of an antioxidant, such
as, a hindered phenol. A hindered phenol that can be used is
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrociannamate. Other
suitable antioxidants are described, for example, in U.S. Pat. No.
7,018,756, incorporated herein by reference in entirety. The
hindered phenol may be present in an amount up to about 10 weight %
based on the concentration or amount of the charge transport
molecule.
[0040] The thickness of the CTL can be from about 5 .mu.m to about
200 .mu.m, or from about 15 .mu.m to about 40 .mu.m. The CTL may
comprise dual layers or plural layers, and each layer may contain a
different concentration of a charge transporting component or
different components.
The Ground Strip Layer
[0041] Another possible layer is a ground strip layer, including,
for example, conductive particles dispersed in a film-forming
material or binder, which may be applied to one edge of the imaging
device component to promote electrical continuity with the
conductive layer or the substrate. The ground strip layer may
include any suitable film-forming material, polymer or binder and
electrically conductive particles as taught herein. Typical ground
strip materials include those enumerated in U.S. Pat. No.
4,664,995, the entire disclosure of which is incorporated by
reference herein.
The Overcoat Layer
[0042] An overcoat layer also may be used to provide imaging device
component surface protection, improved cleanability, reduced
friction as well as improved resistance to abrasion.
[0043] An overcoat may comprise a dispersion of nanoparticles, such
as silica, metal oxides, waxy polyethylene particles, a
polytetrafluoroethylene (PTFE) and the like. The nanoparticles may
be used to enhance lubricity, scratch resistance and wear
resistance of an overcoat layer. In some embodiments, the
nanoparticles are comprised of nanopolymeric gel particles of
crosslinked polystyrene-n-butyl acrylate dispersed or embedded in a
film-forming material, binder or polymer matrix.
[0044] In some embodiments, an overcoat layer may comprise a charge
transport molecule or component. The charge transport molecule may
be present in some embodiments in an amount from about 1% to about
60% by weight of the total weight of an overcoat layer.
[0045] An overcoat layer can include at least a film-forming
material or binder, such as, a resin, and optionally, can include a
hole transporting molecule, such as, a terphenyl diamine hole
transporting molecule. The overcoating layer can be formed, for
example, from a solution or other suitable mixture of the
film-forming material or binder, such as, a resin.
[0046] The film-forming material or binder, such as, a resin, used
in forming the overcoating layer can be any suitable film-forming
material or binder, such as, a resin, including any of those
described herein. The film-forming material or binder, such as, a
resin, can be electrically insulating, semi-conductive or
conductive, and can be hole transporting or not hole transporting.
Thus, for example, suitable film-forming materials or binders, such
as, resins, can be selected from, but are not limited to,
thermoplastic and thermosetting resins such as polycarbonates,
polyesters, polyamides, polyurethanes, polystyrenes,
polyarylethers, polyarylsulfones, polysulfones, polyethersulfones,
polyphenylene sulfides, polyvinyl acetates, polyacrylates,
polyvinyl acetals, polyamides, polyimides, amino resins, phenylene
oxide resins, phenoxy resins, epoxy resins, phenolic resins,
polystyrenes, acrylonitriles, copolymers, vinyl acetate copolymers,
acrylate copolymers, alkyd resins, styrenebutadiene copolymers,
styrene-alkyd resins, polyvinylcarbazoles and the like. A copolymer
may be block, graft, random or alternating.
[0047] In some embodiments, the film-forming material or binder,
such as, a resin, can be a polyester polyol, such as a branched
polyester polyol. The prepolymer is synthesized using a significant
amount of a polyfunctional monomer, such as, trifunctional
alcohols, such as triols, to form a polymer having a significant
number of branches off the main polymer chain or backbone. That is
distinguished from a linear prepolymer that contains only
difunctional monomers, and thus little or no branches off the main
polymer chain or backbone. As used herein, "polyester polyol" is
meant to encompass such compounds that include multiple ester
groups as well as multiple alcohol (hydroxyl) groups in the
molecule, and which can include other groups such as, for example,
ether groups, amino groups, sulihydryl groups and the like.
[0048] Examples of such suitable polyester polyols include, for
example, polyester polyols formed from the reaction of a
polycarboxylic acid, such as, a dicarboxylic acid or a
tricarboxylic acid (including acid anhydrides) with a polyol, such
as, a diol or a triol. The number of ester and alcohol groups, and
the relative amount and type of a polyacid and a polyol, are
selected such that the resulting polyester polyol compound retains
a number of free hydroxyl groups, which can be used for subsequent
crosslinking or derivatization in forming the overcoat. For
example, suitable polycarboxylic acids include, but are not limited
to, adipic acid, pimelic acid, suberic acid, azelaic acid, sebasic
acid and the like. Suitable polyols include, but are not limited
to, difunctional materials, such as glycols or trifunctional
alcohols, such as, triols and the like, including propanediols,
butanediols, hexanediols, glycerine, 1,2,6-hexane triol and the
like. Reference is made to U.S. Pub. No. 2009/0130575.
[0049] In forming the film-forming material or binder for the
overcoating layer in embodiments where the film-forming material or
binder is a polyester polyol, a polyol, or a combination thereof,
any suitable crosslinking agent, a catalyst and the like can be
included in known amounts for known purposes. For example, a
crosslinking agent or an accelerator, such as a melamine
crosslinking agent or an accelerator, can be included with a
polyester polyol reagent to form an overcoating layer.
Incorporation of a crosslinking agent or accelerator provides
reaction sites to interact with the polyester polyol to provide a
branched, crosslinked structure. When so incorporated, any suitable
crosslinking agent or accelerator can be used, including, for
example, trioxane, melamine compounds and mixtures thereof. Where
melamine compounds are used, they can be suitably functionalized to
be, for example, melamine formaldehyde, methoxymethylated melamine
compounds, such as glycouril formaldehyde, benzoguanamine
formaldehyde and the like.
[0050] Crosslinking can be accomplished by heating in the presence
of a catalyst. Thus, the solution of the polyester polyol also can
include a suitable catalyst. Typical catalysts include, for
example, oxalic acid, maleic acid, carbollylic acid, ascorbic acid,
malonic acid, succinic acid, tartaric acid, citric acid,
p-toluenesulfonic acid, methanesulfonic acid and the like and
mixtures thereof.
[0051] If desired or necessary, a blocking agent also can be
included. A blocking agent can be used to "tie up" or block an acid
effect to provide solution stability until an acidic catalyst
function is desired. Thus, for example, the blocking agent can
block an acid effect until the solution temperature is raised above
a threshold temperature. For example, some blocking agents can be
used to block an acid effect until the solution temperature is
raised above about 100.degree. C. At that time, the blocking agent
dissociates from the acid and vaporizes. The unassociated acid is
then free to catalyze polymerization. Examples of such suitable
blocking agents include, but are not limited to, pyridine and
commercial acid solutions containing such blocking agents.
[0052] Any suitable alcohol solvent may be employed for the
film-forming material. Typical alcohol solvents include, for
example, butanol, propanol, methanol, 1-methoxy-2-propanol and the
like and mixtures thereof. Other suitable solvents that can be used
in forming the overcoating layer solution include, for example,
tetrahydrofuran, monochlorobenzene and mixtures thereof. The
solvents can be used in addition to, or in place of, the above
alcohol solvents.
[0053] A suitable hole transport material may be utilized in the
overcoat layer to improve charge transport mobility of the layer.
The hole transport material can be a terphenyl hole transporting
molecule, such as, a terphenyl diamine hole transporting molecule.
In some embodiments, the hole transporting molecule is soluble in
alcohol to assist in application along with the polymer or
film-forming material or binder in solution form. However, alcohol
solubility is not required and the combined hole transporting
molecule and film-forming material or binder can be applied by
methods other than in solution, as needed.
[0054] The thickness of the overcoat layer can depend on the
abrasiveness of the charging (e.g., bias charging roll), cleaning
(e.g., blade or web), development (e.g., brush), transfer (e.g.,
bias transfer roll) etc. functions in the imaging device employed
and can range from about 1 .mu.m or about 2 .mu.m to about 10 .mu.m
or about 15 .mu.m or more. A thickness of between about 1 .mu.m and
about 5 .mu.m can be used. Typical application techniques include
spraying, dip coating, roll coating, extrusion coating, draw bar
coating, wire wound rod coating and the like. The overcoat can be
formed as a single layer or as multiple layers. Setting of the
deposited coating may be obtained by any suitable conventional
technique, such as, oven drying, infrared radiation drying, air
drying and the like. The dried overcoating can transport holes
during imaging. An overcoat may not have too high a free carrier
concentration as free carrier concentration can increase dark
decay. The dark decay of an overcoat can be about the same as that
of the unovercoated device.
[0055] In the dried overcoating layer, the composition can include
from about 40% to about 90% by weight of film-forming material or
binder, or from about 60% to about 10% percent by weight of hole
transporting molecule.
The Anti-Curl Back Coating Layer
[0056] An anti-curl back coating may be applied to the surface of a
substrate opposite to that bearing the photoconductive layer(s) to
provide flatness and/or abrasion resistance, such as, when a web
configuration imaging device component is contemplated. The
anti-curl back coating layer is known and can comprise a
film-forming material or binder, such as, thermoplastic organic
polymers or inorganic polymers that are electrically insulating or
slightly semiconductive. The thickness of anti-curl back coating
layers generally is sufficient to balance substantially the total
forces of the layer or layers on the opposite side of a substrate.
An example of an anti-curl back coating layer is described in U.S.
Pat. No. 4,654,284, the disclosure of which is incorporated herein
by reference in entirety. A thickness of from about 70 .mu.m to
about 160 .mu.m can be used for a flexible device imaging
component, although the thickness can be outside that range as a
design choice.
[0057] Because conventional anti-curl back coating formulations can
suffer from electrostatic charge build up due to contact friction
between the anti-curl layer and, for example, backer bars, which
can increase friction and wear, incorporation of compounds to
dissipate charge, such as, nanopolymeric gel particles, into the
anti-curl back coating layer can substantially eliminate charge
build up. In addition to reducing electrostatic charge build up and
reducing wear in the layer, a charge dissipating material, such as,
nanopolymeric gel particles, may be used to enhance lubricity,
scratch resistance and wear resistance of the anti-curl back
coating layer. In some embodiments, the nanopolymeric gel particles
are comprised of crosslinked polystyrene-n-butyl acrylate, which
are dispersed or embedded in a film-forming material or binder,
such as, a polymer or a matrix.
[0058] In some embodiments, the anti-curl back coating layer may
comprise a charge transport molecule or component. The charge
transport molecule may be present from about 1% to about 60% by
weight of the total weight of the anti-curl back coating layer.
The Undercoat
[0059] A binder or film-forming material or substance, such as, a
resin, a casein, a phenolic resin, a polyol, such as an acrylic
polyol, an aminoplast resin, a polyvinyl alcohol, a nitrocellulose,
an ethylene-acrylic acid copolymer, a polyamide, a polyurethane or
a gelatin can be used, and the layer formed, for example, by dip
coating. Examples of polyol resins include, but are not limited to,
polyglycol, polyglycerol and mixtures thereof. The aminoplast resin
can be, but is not limited to, urea, melamine and mixtures
thereof.
[0060] In various embodiments, phenolic resins can be considered
condensation products of an aldehyde and a phenol compound in the
presence of an acidic or basic catalyst. The phenol compound may
be, for example, phenol, alkyl-substituted phenols, such as,
cresols and xylenols, halogen-substituted phenols, such as,
chlorophenol, polyhydric phenols, such as, resorcinol or
pyrocatechol, polycyclic phenols, such as, naphthol and bisphenol
A, aryl-substituted phenols, cyclo-alkyl-substituted phenols,
aryloxy-substituted phenols and combinations thereof. The phenol
compound may be for example, 2,6-xylenol, o-cresol, p-cresol,
3,5-xylenol, 3,4-xylenol, 2,3,4-trimethyl phenol, 3-ethyl phenol,
3,5-diethyl phenol, p-butyl phenol, 3,5-dibutyl phenol, p-amyl
phenol, p-cyclohexyl phenol, p-octyl phenol, 3,5-dicyclohexyl
phenol, p-phenyl phenol, p-crotyl phenol, 3,5-dimethoxy phenol,
3,4,5-trimethoxy phenol, p-ethoxy phenol, p-butoxy phenol,
3-methyl-4-methoxy phenol, p-phenoxy phenol, multiple ring phenols
and combinations thereof. The aldehyde may be, for example,
formaldehyde, paraformaldehyde, acetaldehyde, butyraldehyde,
paraldehyde, glyoxal, furfuraldehyde, propinonaldehyde,
benzaldehyde and combinations thereof. The phenolic resin may be,
for example, selected from dicyclopentadiene-type phenolic resins,
phenol novolak resins, cresol novolak resins, phenol aralkyl resins
and combinations thereof, see U.S. Pat. Nos. 6,255,027, 6,155,468,
6,177,219, and 6,156,468, each incorporated herein by reference in
entirety. Examples of phenolic resins include, but are not limited
to, formaldehyde polymers with p-tert-butylphenol, phenol and
cresol; formaldehyde polymers with ammonia, cresol and phenol;
formaldehyde polymers with 4,4'-(1-methylethylidene)bisphenol;
formaldehyde polymers with cresol and phenol; or formaldehyde
polymers with p-tert-butylphenol and phenol.
[0061] The phenolic resins can be used as purchased or can be
modified to enhance certain properties. For example, the phenolic
resins can be modified with suitable plasticizers, including, but
not limited to, a polyvinyl butyral, a polyvinyl formal, an alkyd,
an epoxy resin, a phenoxy resin (bisphenol A or epichlorohydrin
polymer), a polyamide, an oil and the like.
[0062] Various types of fine particles and metallic oxides can be
added to adjust the resistance of the undercoat layer. Examples of
such metallic oxides include alumina, zinc oxide, aluminum oxide,
silicon oxide, zirconium oxide, molybdenum oxide, titanium oxide,
tin oxide, antimony oxide, indium oxide and bismuth oxide. Examples
also include extra fine particles of tin-doped indium oxide,
antimony-doped tin oxide and antimony-doped zirconium oxide. A
single species of a metallic oxide can be used or two or more types
can be used in combination. When two or more are used, the plural
oxides can be used in the form of a solid solution or a fused
substance. The average particle size of a metallic oxide can be
about 0.3 .mu.m or less, or about 0.1 .mu.m or less. In some
embodiments, metallic oxide particles can be surface treated.
Surface treatments include, but are not limited to, exposure of the
particles to aluminum laurate, alumina, zirconia, silica, silane,
methicone, dimethicone, sodium metaphosphate and the like and
mixtures thereof.
[0063] The solvent used for preparing the undercoat, depending on
the presence of additives therein, is one capable of, for example,
effective dispersion of inorganic particles and dissolution of the
film-forming material or substance. A suitable solvent can be an
alcohol, such as those containing 1, 2, 3, 4, 5 or 6 carbons, such
as, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol,
t-butanol and sec-butanol. Further, to improve storage ability and
particle dispersion, it is possible to use an auxiliary solvent.
Examples of such an auxiliary solvent are methanol, benzyl alcohol,
toluene, methylene chloride, cyclohexane and tetrahydrofuran.
[0064] When particles are dispersed in a binder, resin or
film-forming material or substance to prepare an undercoat, the
particles can be present in an amount of about 20 wt % to about 80
wt %; from about 30 wt % to about 70 wt %; from about 40 wt % to
about 60 wt %; or from about 50 wt % to about 60 wt % of the total
weight of undercoat materials. In other embodiments, the particles
can be present in an amount from about 30 wt % to about 80 wt %;
from about 40 wt % to about 80 wt %; from about 50 wt % to about 80
wt %; from about 60 wt % to about 80 wt %; from about 20 wt % to
about 70 wt %; from about 40 wt % to about 70 wt %; or from about
50 wt % to about 70 wt %; from about 60 wt % to about 70 wt %; from
about 20 wt % to about 60 wt %; or from about 30 wt % to about 60
wt % of the total weight of undercoat materials.
[0065] An ultrasonic homogenizer, ball mill, sand grinder or
homomixer can be used to disperse the inorganic particles.
[0066] The method of setting the undercoat can be selected as
appropriate in conformity with the type of solvent and film
thickness. For example, drying by heat can be used.
[0067] The film thickness of the undercoat layer can be about 0.1
.mu.m to about 30 .mu.m, or from about 1 .mu.m to about 20 .mu.m,
or from about 4 .mu.m to about 15 .mu.m. Thus, the undercoat can be
about 5 .mu.m, about 6 .mu.m, about 7 .mu.m, about 8 .mu.m, about 9
.mu.m, about 10 .mu.m, about 11 .mu.m, about 12 .mu.m, about 13
.mu.m or about 14 .mu.m in thickness.
Photoreceptor Deconstruction
[0068] Photoreceptors can be salvaged for reuse or the components
recycled if the various layers thereon can be removed readily from
the substrate. Various methods currently are employed, including
cutting or lathing the layers from the substrate; exfoliating the
layers by repeated heating and cooling; heating followed by a
chemical treatment; rigorous chemical treatment; and heating under
vacuum. Each of those methods, however, has limitations. For
example, the removal processes are labor intensive; require an
inordinate amount of manufacturing space; use toxic materials or
materials requiring special disposal procedures; and may involve
heat and solvents which can damage the substrate. Some of the
methods also may generate dust or emit harmful vapors or poisonous
substances and may use or produce environmentally incompatible
solvents and products. Often, the processes are costly, making
selling the photoreceptor as scrap more cost effective.
[0069] Electrophotographic imaging device components with a drum
configuration require additional steps for reuse or recycling. For
example, drum-type photoreceptors are usually supported on an
electrically conductive shaft by hubs or end flanges. Often the hub
or end flange is secured to the end of the drum by a resin
adhesive. To clean and to recycle the used or defective drum-type
photoreceptor, the hubs or end flanges must be removed and the
resin adhesive must be stripped off the photoreceptor. Such removal
techniques may damage the underlying substrate, may involve complex
equipment, are time intensive and may involve solvents which
require special handling and/or disposal.
[0070] Thus, there is a need for a photoreceptor material or
component that facilitates removal of the layers from a substrate,
which will reduce pollution, which will reduce the area dedicated
to photoreceptor salvage, which reduces the need to scrap an
otherwise recyclable photoreceptor, which enables reuse of the
substrate, which enables recycling and regeneration of materials
comprising the various layers, and which is faster and relatively
less costly to implement than current, conventional removal or
stripping methods.
[0071] Incorporation of a sulfonamide in an undercoat, and
optionally, if present, also in a hole blocking layer, provides a
layer(s) that continues to provide the functions ascribed and
desired for an undercoat, or a hole blocking layer when present, as
described herein and as known in the art, while also providing for
a layer that can be removed from a substrate under conditions that
do not require toxic solvents, extreme temperatures, a vacuum and
so on, as currently used. In some embodiments, the terms undercoat
and hole blocking layer are used interchangeably, or refer to a
single layer with combined functions, which layer is the first
layer applied to a substrate.
[0072] When deconstructing a sulfonamide-doped undercoat as taught
herein, a stripping solvent comprising about 75% to about 85% w/v
or v/v of an aprotic polar material; about 5% to about 15% w/v or
v/v of a weak acid, such as, an organic acid containing a
carboxylic acid; and the remainder, when needed, being water, can
be used with the sulfonamide-doped undercoat of interest, and
devices carrying same. Examples of an aprotic polar material
include dimethyl sulfoxide, formamide, dioxane, tetrahydrofuran,
dichloromethane, ethyl acetate, acetone, acetonitrile,
N-methylpyrrolidone and so on, as known in the art. Examples of
weak acids include lactic acid, citric acid, acetic acid, formic
acid, oxalic acid, uric acid and so on. The treatment can be
conducted at about 65.degree. C. to about 95.degree. C. For
example, a stripping solution composed of 80% N-methylpyrrolidone,
8% citric acid and 12% water completely removed all organic layers
including a sulfonamide-doped undercoat from a substrate when the
photoreceptor was incubated in that stripping solvent for 5 minutes
at 85.degree. C.
[0073] Suitable sulfonamides that can be used in an undercoat of
interest have the following formula:
##STR00001##
[0074] wherein R.sub.1 is H or an alkyl which can range from 1
carbon to about 20 carbons in length. The alkyl can be linear,
cyclic or branched, or can contain one or more rings of varying
size. Hence, the alkyl can be a methyl, ethyl, propyl, butyl,
pentyl, hexyl, heptyl, octyl, nonyl, decyl and so on group,
including hydrocarbons containing 11, 12, 13, 14, 15, 16, 17, 18 19
or 20 carbons. The alkyl group can be saturated or can contain one
or more double or triple bonds. One or more of the carbons of an R
group can be substituted with a functional group, such as a
hydroxyl, a sulfhydryl, an amino and so on group.
[0075] Each of R.sub.2-6 is H or an alkyl which can range from 1
carbon to about 20 carbons in length. The alkyl can be linear,
cyclic or branched, or can contain one or more rings of varying
size. Hence, the alkyl can be a methyl, ethyl, propyl, butyl,
pentyl, hexyl, heptyl, octyl, nonyl, decyl and so on group,
including hydrocarbons containing 11, 12, 13, 14, 15, 16, 17, 18 19
or 20 carbons. The alkyl group can be saturated or can contain one
or more double or triple bonds. One or more of the carbons of an R
group can be substituted with a functional group, such as a
hydroxyl, a sulfhydryl, an amino and so on group.
[0076] In some embodiments, R.sub.1 is H. In other embodiments,
R.sub.1 is C.sub.1 to about C.sub.5. Also, one or more of the
carbons can be substituted. Suitable substituents include hydroxyl,
sulfhydryl and amino. In other embodiments, each of R.sub.2-R.sub.6
is H. In yet other embodiments, R.sub.2 or R.sub.6 is C.sub.1 to
about C.sub.3, with the remaining R groups on the benzyl group
being H. In some embodiments, R.sub.2 or R.sub.6 is methyl, with
the remaining R groups on the benzyl group being H.
[0077] Examples of suitable sulfonamides that can be used in an
undercoat of interest are available commercially, for example, from
Unitex Chemical Corp., Greensboro, N.C., where such compounds are
included in the Uniplex product line, and include N-butyl benzene
sulfonamide (Uniplex 214), o,p-toluene sulfonamide (Uniplex 171),
N-ethyl-o,p-toluene sulfonamide (Uniplex 108) and
N-(2-hydroxylpropyl) benzene sulfonamide (Uniplex 225). Each
species of sulfonamide can be used alone or in combination.
[0078] The sulfonamide is mixed with the other components of an
undercoat forming liquid, or optionally, in a hole blocking layer,
if present, forming liquid, and thus, is one which is soluble in
the solvent(s) used. The total amount of sulfonamide used is about
1% to about 10%; about 2% to about 9%; about 3% to about 8%; about
4% to about 7%; or about 5% to about 6% by weight or volume of the
total volume of undercoating solution. Once the sulfonamide is in
solution, the undercoat is formed and is set as taught herein, such
as dip coating with heating or other form of drying.
[0079] Thus, an undercoat of interest is one which does not impact
negatively any of the functions normally ascribed to an undercoat
and does not impact negatively the overall function of a
photoreceptor. Thus, the electrical properties of the
photoconductor, as evidenced for example, by PIDC's, are comparable
to that of a control photoconductor not containing or lacking a
sulfonamide-doped undercoat; or there is no adverse impact on print
quality, as evidenced, for example, in comparable levels of
ghosting, for example A zone and/or J zone ghosting as compared to
a photoreceptor comprising an undercoat lacking a sulfonamide; or
the undercoat adheres to the substrate to the same extent as a
control undercoat lacking a sulfonamide. However, an undercoat of
interest is one which is removed from a substrate using normal
solvents and buffers, for example, a buffer containing an aprotic
polar material and/or a weak acid, and under unremarkable treatment
conditions, such as, at atmospheric pressure, that is, a vacuum is
not needed and/or temperatures less than about 100.degree. C., less
than about 95.degree. C., less than about 90.degree. C., less than
about 85.degree. C., less than about 80.degree. C., less than about
75.degree. C. and so on.
[0080] An undercoat, and when present, optionally, a hole blocking
layer, of interest, is used in a photoreceptor as provided herein.
Then, the remaining layers to yield a functional photoreceptor are
added to the undercoat, at least a CGL and a CTL, as taught herein
or as known in the art. An undercoat of interest can be used with
any organic photoreceptor independent of the specific substrate and
independent of the specific other layers that comprise a
photoreceptor. The completed photoreceptor is engaged in an imaging
device as known in the art to enable the production of an image
product, for example, photocopies. Hence, such an imaging device
can comprise a device for producing and removing an imagewise
charge on the photoreceptor. The imaging device can contain a
developing component for applying a developing composition, such as
a finely divided pigmented material to said charge retentive
surface of said photoreceptor to yield an image on the surface of
said photoreceptor. Such an imaging device also may include an
optional transferring component for transferring the developed
image from the photoreceptor to another member or to a copy
substrate or receiving member. The imaging device also contains a
component for affixing the finely divided pigmented material onto a
receiving member. It will be evident the photoreceptor can be
disposed as a removable or replaceable component of the imaging
device. The photoreceptor, when treated with the stripping solvent
of interest, as provided herein, will yield a reusable substrate
and a solution containing the organic layer components suspended or
dissolved therein.
[0081] Hence, should there be a defect in a photoreceptor, a
photoreceptor is showing wear or an imaging device is targeted for
replacement, a photoreceptor of interest can be destined for ready
reclamation, reconditioning or recycling of the components thereof
in a safe and cost efficient fashion by exposing a photoreceptor of
interest comprising an undercoat of interest to a stripping
solvent, such as that taught herein, to obtain a substrate free of
coatings and the various coating components in solution.
[0082] Various embodiments of interest now will be exemplified in
the following non-limiting examples.
EXAMPLES
Comparative Example 1
[0083] A hole blocking layer or undercoat layer dispersion was
prepared by milling 18 g or 60 wt % of TiO.sub.2 (MT-150W,
manufactured by Tayca Co., Japan), and 24 g or 40 wt % of the
phenolic resin, VARCUM.TM. 29159, (OxyChem Co., a formaldehyde,
phenol, p-tert-butylphenol, cresol polymer in a solvent mixture of
xylene/1-butanol, 50/50, weight average molecular weight, M.sub.w,
of 2,000) with a total solid content of about 48 wt % in an
attritor mill with about 0.4 mm to about 0.6 mm diameter ZrO.sub.2
beads for 6.5 hours. The dispersion was filtered though a 20 .mu.m
Nylon filter. A 30 mm aluminum drum substrate then was coated with
the aforementioned filtered dispersion by spray coating. After
drying at 160.degree. C. for 20 minutes, a hole blocking layer of
TiO.sub.2 and the phenolic resin (TiO.sub.2/phenolic resin ratio of
60/40) about 8 .mu.m in thickness was obtained.
[0084] A photogenerating layer comprising chlorogallium
phthalocyanine was deposited on the above hole blocking layer or
undercoat layer at a thickness of about 0.2 .mu.m. The
photogenerating layer coating dispersion was prepared by mixing 2.7
g or 5.4 wt % of chlorogallium phthalocyanine (ClGaPc) Type C
pigment, 2.3 g or 4.6 wt % of the polymeric binder, VMCH (carboxyl
modified vinyl copolymer, Dow Chemical Company), 15 g or 30 wt % of
n-butyl acetate and 30 g or 60 wt % of xylene. The resulting
mixture was milled in an attritor mill with about 200 g of 1 mm
Hi-Bea borosilicate glass beads for about 3 hours. The dispersion
mixture obtained then was filtered through a 20 .mu.m Nylon cloth
filter resulting in a solids content of the dispersion after
dilution of about 6 wt %.
[0085] Subsequently, using known spray processes, a 30 .mu.m thick
CTL was coated on top of the photogenerating layer using a
dispersion prepared from
N,N'-diphenyl-N,N-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine
(5.38 g or 13.4 wt %), a film-forming polymer binder, PCZ-400
([poly(4,4'-dihydroxy-diphenyl-1-1-cyclohexane, M.sub.w=40,000)]
available from Mitsubishi Gas Chemical Company, Ltd.) (7.13 g or
17.7 wt %) and PTFE POLYFLON.TM. L-2 microparticles (1 g or 2.5 wt
%) available from Daikin Industries in a solvent mixture of 20 g or
49.7 wt % of tetrahydrofuran (THF), and 6.7 g or 16.7 wt % of
toluene processed through a CAVIPRO.TM. 300 nanomizer (Five Star
Technology, Cleveland, Ohio). The CTL was dried at about
120.degree. C. for about 40 minutes.
Example 1
Preparation of Photoreceptor with Sulfonamide-Doped Undercoat
[0086] A photoconductor was prepared by repeating the above process
of Comparative Example 1, except that 1.5 g or 4.8 wt % of the
sulfonamide, N-butyl benzene sulfonamide, obtained from Unitex
Chemical, was added into the hole blocking layer dispersion of
Comparative Example 1, with the amounts of the remaining
ingredients reduced accordingly.
[0087] A 30 mm aluminum drum substrate then was coated with the
aforementioned generated dispersion. More specifically, after
drying at 160.degree. C. for 20 minutes, a hole blocking layer of
TiO.sub.2 in a mixture of phenolic resin and the above N-butyl
benzene sulfonamide (TiO.sub.2/phenolic resin/N-butyl benzene
sulfonamide ratio of 57.1/38.1/4.8) was coated on the 30 mm
aluminum drum in accordance with the process of Comparative Example
1 resulting in an about 8 .mu.m thick hole blocking layer.
Example 2
Comparative Studies
Electrical Property Testing
[0088] The above prepared photoconductors of Comparative Example 1
and of Example 1 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 (PIDC) from
which the photosensitivity and surface potentials at various
exposure intensities were 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 photoconductors were tested at surface potentials
of 700 volts with the exposure light intensity incrementally
increased by regulating a series of neutral density filters. The
exposure light source was a 780 nm light emitting diode. The
xerographic simulation was conducted in an environmentally
controlled, light tight chamber at dry conditions (10% relative
humidity and 22.degree. C.).
[0089] The above prepared photoconductors exhibited substantially
similar PIDCs. Thus, incorporation of the sulfonamide of Example 1
into the hole blocking or undercoat layer did not adversely impact
the electrical properties of the photoconductor.
Ghosting Measurement
[0090] The Comparative Example 1 and the Example 1 photoconductors
were acclimated at room temperature for 24 hours before testing in
a closed container chamber (85.degree. F. and 80% humidity) for A
ghosting. Print testing was accomplished in the Xerox Corp.
WorkCentre.TM. Pro C3545 using the K (black toner) station at t of
500 print counts (t=500 is the 500.sup.th print) and in the CMY
station of the color WorkCentre.TM. Pro C3545 which operated from t
of 0 to t of 500 print counts. The prints for determining ghosting
characteristics include placing an X symbol or letter on a half
tone image. When X is invisible, the ghost level is assigned Grade
0; when X is barely visible, the ghost level is assigned Grade 1;
and Grade 2 to Grade 5 refer to the level of visibility of X with
Grade 5 being a dark and visible X. Ghosting levels were visually
measured against an empirical scale, the lower the ghosting grade
(absolute value), the better the print quality. The ghosting
results are summarized in Table 1.
[0091] The Comparative Example 1 and Example 1 photoconductors were
also acclimated in J zone conditions (75.degree. F. and 10%
humidity) in a closed container chamber for 24 hours before print
tested, as above, to assess J zone ghosting. The ghosting results
also are summarized in Table 1.
TABLE-US-00001 TABLE 1 A Zone Ghosting J Zone Ghosting UCL
Composition T = 500 prints T = 500 prints Comparative Example 1
Grade - 5 Grade - 6 (No Sulfonamide) Example 1 (4.8 Wt % of Grade -
3 Grade - 4.5 Sulfonamide)
[0092] Incorporation of the sulfonamide into the undercoat layer
(UCL) reduced ghosting by about 2 grades in the A zone and by about
1.5 grades in the J zone, which reduction results in superior
xerographic print quality, as determined by visual observation.
Adhesion Test
[0093] The adhesion characteristics of the Comparative Example 1
and the Example 1 photoconductors, between the hole blocking or
undercoat layer and the aluminum drum substrate thereof, was tested
using the following process.
[0094] The photoconductor drums were scored with a razor in a
crosshatch pattern at about 4 mm to about 6 mm spacing. A 1 inch
piece of commercially available scotch tape (3M) then was affixed
to the scored site of each photoconductor, and then removed to
determine the amount of delamination of the layered material onto
the adhesive tape. The results are summarized in Table 2. The scale
ranges from Grade 1 to Grade 5 where Grade 1 is almost no
delamination and Grade 5 is almost complete delamination.
TABLE-US-00002 TABLE 2 UCL Composition Adhesion Grade Comparative
Example 1 (No Sulfonamide) 1.5 Example 1 (4.8 Wt % of the
Sulfonamide) 1.5
[0095] Incorporation of the sulfonamide into the undercoat or hole
blocking layer had substantially no impact on the adhesion
characteristics between the hole blocking or undercoat layer and
the substrate.
Coating Layers Removal
[0096] The photoconductors of Comparative Example 1 and of Example
1 separately were immersed in a solution of 80 wt % of
N-methyl-2-pyrrolidone (NMP), 8 wt % of citric acid and 12 wt % of
water at 85.degree. C. The hole blocking coating layer removal of
the experimental photoreceptor was compared with the immersion time
and the % of the hole blocking layer removal of the control by
visual observation, resulting in the data summarized in Table 3.
The aluminum substrate is a shiny silver color while the coating
layer is green.
[0097] It was determined by visual observation by the absence of
the green color that by adding the sulfonamide to the hole blocking
or undercoat layer, the coating layers of the experimental
photoreceptor were removed completely in the stripping
protocol.
TABLE-US-00003 TABLE 3 UCL Composition Incubation Time of Coating
Layer Reaction Comparative Example 1 At 10 Min., ~90% of Coating
Layers Remain (No Sulfonamide) Example 1 (4.8 Wt % of 5 Min. for
Complete Removal (100%) of All Sulfonamide) Coating Layers
[0098] Incorporation of the sulfonamide in the hole blocking layer
facilitated layer removal, only a 5 minute incubation was needed to
completely remove the coating layers from the substrate for the
Example 1 photoconductor. In contrast, after 10 minutes, 90% of the
coating layers (including CTL, CGL and UCL) remained on the
substrate of the Comparative Example 1 photoconductor (no
sulfonamide in the undercoat layer).
[0099] All references cited herein are herein incorporated by
reference in entirety.
[0100] It will be appreciated that variants of the above-disclosed
and other features and functions, or alternatives thereof, may be
combined with other and different systems or applications. Various
presently unforeseen or unanticipated alternatives, changes,
modifications, variations or improvements subsequently may be made
by those skilled in the art to and based on the teachings herein
without departing from the spirit and scope of the embodiments, and
which are intended to be encompassed by the following claims.
* * * * *