Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2002-05-10
2003-11-11
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S078000, C430S134000, C430S135000
Reexamination Certificate
active
06645687
ABSTRACT:
PENDING APPLICATION AND PATENTS
Illustrated in copending application U.S. Ser. No. 09/815,116, now U.S. Pat. No. 6,492,080, the disclosure of which is totally incorporated herein by reference, is a process comprising
forming a first chlorogallium phthalocyanine (ClGaPc) in N-methyl-2-pyrrolidinone (NMP) to form a ClGaPc (NMP) Type I product;
forming a second chlorogallium phthalocyanine in dimethyl sulfoxide (DMSO) to form a ClGaPc (DMSO) Type I product;
separately dry milling and then wet treating the Type I products to form respective Type II products;
blending the Type II products together along with a resin to form a coating mixture; and
coating the mixture to form a photoconductive charge generator layer in an electrostatographic imaging article.
BACKGROUND
The present application discloses photoconductive compositions comprising gallium phthalocyanines, and more specifically, chlorogallium phthalocyanine (ClGaPc) and hydroxygallium phthalocyanine (HOGaPc) pigments. In embodiments, there are disclosed photoreceptors or photoresponsive devices, and imaging apparatus and processes thereof. More specifically, disclosed are improved photoresponsive devices comprised of a photogenerating layer and a transport layer, and processes for selecting or fine tuning the sensitivity of photoresponsive devices by including in the photogenerator layer of the device a mixture of chlorogallium phthalocyanine (ClGaPc) pigment particles, and hydroxygallium phthalocyanine (HOGaPc) pigment particles.
The photoresponsive imaging members are useful in various imaging and printing systems, including those systems wherein electrostatic latent images are formed on the imaging member. Additionally, the photoresponsive members illustrated herein can be irradiated with light, for example, as generated by a known laser to accomplish, for example, latent image formation by, for example, charged area development (CAD) or discharged area development (DAD) methodologies.
Advantages in embodiments with a mixture of pigments illustrated herein is that the article and processes thereof afford charge generator pigment compositions which can be readily varied or adjusted in photosensitivity properties while retaining excellent electrical properties; the article and processes thereof afford charge generator pigment compositions which can be readily varied or adjusted in photosensitivity properties to, for example, accommodate variations which result from manufacturing photoreceptors in different locations as may be desired, for example, for economic or other business reasons; the article and processes thereof permit charge generator pigment compositions which can be readily varied or adjusted in photosensitivity properties as desired to accommodate changes which may occur as a copier or printer machine has been modified with new or replacement electrical components that cause some shift in image quality, and the charge generator chlorogallium phthalocyanine can be prepared in the absence of a solven, such as dimethylsulfoxide (DMSO), quinoline, chloronaphthalene which possesses an odor and decomposes into toxic and very odorous compounds when heated at high temperature>100° C.
With the mixtures illustrated herein, such as a mixture of ClGaPc and HOGaPc, there is enabled a wide range of photosensitivity values from that of ClGaPc, a lower sensitivity material, to that of HOGaPc, a higher sensitivity material. The photosensitivity of HOGaPc can be about 50 percent or more than that of ClGaPc; and the photosensitivity of the blended mixture of these two pigments can be preselected primarily because of the linear dependence relationship of the composition. For the blended pigment mixtures, the plot of photosensitivity values versus the composition of pigment in terms of weight percent of either one of two pigments can evidence an excellent linear dependency with a regression coefficient R
2
approaching unity (the commonly used photosensitivity values are either the E
½
, exposure energy required for 50 percent photodischarge, or the E
⅞
exposure energy required for 87.5 percent photodischarge); for the pigment mixtures illustrated herein in embodiments the E
½
, R
2
is 0.985 and for E
⅞
, R
2
is 0.964. For example, when the photosensitivity of ClGaPc is E
⅞
=x ergs/cm
2
and HOGaPc is E
⅞
=y ergs/cm
2
, the final photosensitivity of a pigment mixture containing m weight percent of ClGaPc and n weight percent of HOGaPc, where the (m+n) amounts to the total pigment weight (100 percent), has a value of about E
⅞
=(mx+ny)÷100 ergs/cm
2
. Similarly, if E
½
of the ClGaPc=a ergs/cm
2
and HOGaPc is E
½
=b ergs/cm
2
the final photosensitivity of the mixture in terms of E
½
can be predicted from the equation E
½
=(ma+nb)÷100 ergs/cm
2
. The linear range of sensitivities can be fashioned by blending varying amounts of ClGaPc with HOGaPc.
Also, the disclosed herein blend in embodiments can be used to fine tune the photosensitivity of the charge generator pigment material to a desired target value; thus the blend permits one to change the site of the photoreceptor or photoreceptor component manufacturer for economic or other business reasons, and the blend approach can be readily adapted and used to adjust the relative composition of the blended pigments to further fine tune the photosensitivity of the charge generator pigment material to certain desired values and to compensate for differences arising from other unpredictable variations in a specific manufacturing plant process. The photosensitivity adjustment can also allow a wider latitude in the manufacture of the photogenerator pigment, thus significantly reducing the cost of the pigment production process. To prepare a pigment with tight performance characteristics for only a specific device is not usually cost effective as the range of product applications is very limited, and also the expenses involved in controlling pigment process to yield narrow range of photoreceptor characteristics could become prohibitably high. The ability to adjust photoreceptor sensitivity by blending ClGaPc pigment with a HOGaPc pigment can provide a mixed pigment product with particles that possess high surface area, afford high dispersability, and have high stability against agglomeration in coating formulations and coating processes. The particles of different pigment crystals tend to repel each other hence reducing their tendency to associate to form large agglomerates which can degrade the printing resolution quality.
Numerous photoresponsive devices for electrostatographic imaging systems are known including selenium, selenium alloys, such as arsenic selenium alloys; layered inorganic photoresponsive, and layered organic devices. Examples of layered organic photoresponsive devices include those containing a charge transporting layer and a charge generating layer, or alternatively a photogenerator layer. Thus, for example, an illustrative layered organic photoresponsive device can be comprised of a conductive substrate, overcoated with a charge generator layer, which in turn is overcoated with a charge transport layer, and an optional layer overcoated on the charge transport layer. In a further variation of this device the charge transporter layer can be overcoated with a photogenerator layer. Examples of generator layers that can be employed in these devices include, for example, certain components, like selenium, cadmium sulfide, vanadyl phthalocyanine, and x-metal free phthalocyanines, dispersed in a binder resin, while examples of transport layers include dispersions of various diamines, reference for example, U.S. Pat. No. 4,265,990, the disclosure of which is incorporated herein by reference in its entirety.
There continues to be a need for photoresponsive devices, and improved imaging systems utilizing such devices. Additionally, there continues to be a need for photoresponsive devices of varying sensitivity, which devices a
Burt Richard A.
Hor Ah-Mee
Liebermann George
Vong Cuong
Goodrow John
Palazzo E. O.
Xerox Corporation
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