CA1103972A - Photosensitive compositions containing vanadyl phthalocyanine and a phenzine desensitizing dye - Google Patents
Photosensitive compositions containing vanadyl phthalocyanine and a phenzine desensitizing dyeInfo
- Publication number
- CA1103972A CA1103972A CA289,286A CA289286A CA1103972A CA 1103972 A CA1103972 A CA 1103972A CA 289286 A CA289286 A CA 289286A CA 1103972 A CA1103972 A CA 1103972A
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- Canada
- Prior art keywords
- photosensitive composition
- phenyl
- pigment
- vanadyl phthalocyanine
- desensitizing
- Prior art date
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Abstract
IMPROVED PHOTOSENSITIVE COMPOSITIONS
USEFUL IN PHOTOELECTROPHORETIC IMAGING
ABSTRACT OF THE DISCLOSURE
Disclosed are photosensitive compositions containing vanadyl phthalocyanine pigment and minor amounts of at least one compound of the formula wherein X and Z are independently selected from the group consisting of -NH2 and -NHR;
R is phenyl or phenylsulfonate;
Y is phenyl; and m and n can range from 0 to 2, with the proviso that either m or n is at least 1 In practice such compositions are rountinely dispersed in an insulating carrier fluid and the resultant dispersion employed in photoelectrophoretic imaging processes.
USEFUL IN PHOTOELECTROPHORETIC IMAGING
ABSTRACT OF THE DISCLOSURE
Disclosed are photosensitive compositions containing vanadyl phthalocyanine pigment and minor amounts of at least one compound of the formula wherein X and Z are independently selected from the group consisting of -NH2 and -NHR;
R is phenyl or phenylsulfonate;
Y is phenyl; and m and n can range from 0 to 2, with the proviso that either m or n is at least 1 In practice such compositions are rountinely dispersed in an insulating carrier fluid and the resultant dispersion employed in photoelectrophoretic imaging processes.
Description
~397Z
BACKGROU~D OF THE I~VENTIOl~
Field of the Invention - This invention relates to compositions and methods of use of such compositions. More specifically, this invention is directed to vanadyl phthalo-cyanine/dye compositions and fluid dispersionsthereof. 'rhese fluid dispersions are useful in photoelectro-phoretic imaging processes.
Description o the Prior Art - As is generally recognized in the artt a photoelectrophoreti* imaging system is on~ wherein electrically photosansitive particles dispersed ( in a carrier liquid are initially subtjected to an electric field and either simultaneously or thereafter exposed to aetivating eleetromagn,atic radiation conforming to an image pattern. Photoelectrophoretie imaging techniques may be adapted for the preparation of both monochrDmatic and poly-chromatic reproductions. A detailed disclosure of both the monatchromatic and polyehromatie photoelectrophoretic imaging systems ean be ound in U.S. Patents 3,383,993; 3,384,488;
3,384,565 and 3,384,566. In one of the preferred embodiments of the photoelectrophoretic imaging method deseribed in the above patents, a layer of an imaging suspension eomprising eleetrically photosensitive pigment partieles in an insulating earrier liquid is confined between an injeetin~ eleetrode ~; and a blockint~ electrode (at least one of the eleetrodes being ; 2~ ~at least partially transparent); the photosensitive dispersion s~bjected to an applied eleetrie field; and thereafter exposed ; to aetivating~elqctromagnetic radiation conforming to an image pattern. Typically,~ eomplementary images are formed on the opposing surf'aces of the electrodes whieh are in eontaet with the dispersion of pigment particles. In a monochromatic system, pigment partieles of only one color are required, , : :
X
~,:, . ~ :
11~339~7z however, particles o~ more than one shade of the same color may be utilized if it is desired to provide the capability to produce a range of monochromatic colors. In a polychror,~atic system, images of more than one cGlor, and preferably full color, may be formed by utilizing a plurality of differently colored pigment particles which ideally have spectral response curves which do not substantially overlap each other, thereby providing the necessary color separation. In the preferrecl photoelectrophoretic imaging system re~erred to hereinabove, the pigment particles correspond to the subtractive colors yellow, c~an and magenta, The yellow pigment particles are primaril~ responsive to light with~n the blue region of the electromagnetic spectrum; the cyan particles are primarily photoresponsive to light within the red portion of the electro-magnetic spectrum; and the magenta particles are primarilyresponsive to light within the green portion o~ the electro-magnetic spectrum. Therefore, when a full color reproduction is projected upon a suspension containing these three pigments, the cyan particles will respond to those portions of the ~lage input corresponding to the color red, and upon being photo-activated will migrate from the electrode surface on which the image i5 to he formed thereby leaving beh.~nd the yellow and magenta pigment particles which togethex appear as red~
Similarly, image input corresponding to green light will cause magenta parti~les to migrate and image input corresponding to blue light will cause the yellow particles to migrate.
Where white light imringes upon tre suspension containing , .
~ -4-.. . ...
. ' - .` `
11~39~z the above three pigment particles, all such particles should migrate thereby leaving the surfa~e of the image substantially devoid of pigment. ~le resulting image can thereafter be transferr ~ to a receiving sheet such as white paper and thus the portions of the image which are deficient of pigment will appear as white in the finished copy. In order to obtain good colcr separation, it would be preferable that each pigment migrate only in response t:o activating electromagnetic radiation within its principal region of absorption.
Due to electrical interactic-~s between the pigments and other unknown factors, photosl:imulated particle migration is often incomplete resulting in t~aces of the "subtracted"
pigment remaining at the injectiny electrode thereby imparting undesired color to the image residing on this electrode.
lS As is discussed in the patents previously incorporated by reference, the pigment particles used in photoelectrophoretic imaging systems are initially charged and ca~sed to migrate to the surface of one of two opposing electrodes in response to an electric field established ~etween these electrodes.
Upon absorption of light within i~s principal region of photores~onse, these pigments, it is theorized, generate hole-electron pairs, and depending upon the relative mobility of these charge carriers in the pigment, either one or both of ; ; these charge carriers are injecte~ into the liquid carrier medium. Upon the injection of only one species of carrier ~!:
' `
t in~o the medium, the particle will thereby acquire a net , ~
;~ -5-, , :
~1~39~2 charge wllicll preferably will be identical in sign to the polarity of charge of the electrode to which it had previously migrated. This similarity in charge will cause the pigment particle to be repelled by this formerly attractive electrode resulting in its migration to the surface of the opposing electrode where it forms a complementary image. It will be appreciated thct if the above theoretical explanation is correct, the injection of both species of charge carrier into the liquid caYrier medium will result in a failure to generate the desired ir.lage. Moreover, in the event of indiscriminate injection of charge carriers from the photoactivated pigment into th~ liquid carrier medium and the subseguent transfer of such carriers to a nonphoto-~ activated particle, the non~hotoactivated pigment particle 1 15 will migrate just as if it had absorbed the imaging energy.
This migration of nonphotoactivated particles will seriously impair color separation in the desired reproduction.
It thus appears that in order for good colorseparation to be maintained and faithful reproduction of an original to be achieved, it is necessary to maintain selective electrophotographic response of the pigments to their colors of primary absorption. It is also apparent , .
that this can only be achieved by preventing indiscriminate injection of charge carriers from photoactivated pigments into the liquid carrier medium, The prior art contains frequent reference to various treatment of photoelectrophoretic pigments with i '' `~
:
, ~ :
~lQ39q2 diverse material.s in order to modify or enhance the electro-photographic response of such pigments For example, th~ literature discloses: (a) the adsorption of ~onor and acceptor molecules on pic~
ments utilized in photoelectrophoretic imaging (b) thè inc:'usion of such electrically active materials in the insulating liquid carrier containing such pigment parti~les, or (c) the application of these e lectrically active materials to one of the electrodes used in confii-ing the pigment dispersion.
All of tha above treatments are said to result in charge transfer complex :Eormation between the pigments and these electrically active materials, thereby facilitating injection of electrons from photoactivated p gment particles into the surrounding medium, U,S, Application Serial No, 566, 846, filed July 21, 1966, now abandoned; pub]ished in Japan on March 30, 1970, Application Serial No, 4636667, filed July 20, 1967 Photoactive polymeric materials have also been disclosed as effective in modification of the electrophoretic response of pigment particles used in photoelectrophoretic ~: imaging systems, U,S Application Serial No. 863, 507, file~October 3, 1969, published in Holland on P~pril 6, 1971 as Application Serial No, 70.14614. Poly(N-vinylcarbazole) i5 diselosed in this Dutch patent as useful in the agglomeration - ~ , and/or eneapsulation of ph~tomigratory pigment particles thereby enhancing the electrophotographic response of these particles 25 to imaging energies, Although the prior art systems described above ~ ~ :
~ enable substantia1 enhancement in the photoresponse eharaeter-:~ isties of photomigratory pigment particles used in ph~toe lectro-:: phoretic lmaging, further improvement is still required ::
:~' ,, , . ~ -~.~V3g7Z
especially with regard to the problems associated with color separation and reduction in D
mln It is, therefore, an object of an aspect of this invention to remedy the above, as well as-related deficiencies in the prior art.
More specifically, it is an object of an aspect of this invention to modulate the photoelectric response of certain photomigratory pigments so as to control the indis-criminate injection of charge carriers generated within such pigments from influencing the movement of nonphotoactivated pigments.
An object of an aspect of this invention is to provide a photomigratory pigment composition having improved selective response to activating electromagnetic radiation.
Additional objects of this invention include the use of the above compositions in photoelectrophoretic and photo-immobilization electrophoretic recording systems and methods.
SUM~RY OF THE INVENTION
In accordance with one aspect of this invention there is provided a photosensitive composition comprising an insulating carrier liquid having dispersed therein from about 0.1 to about 10 weight percent vanadyl phthalocyanine pigment and, based upon vanadyl phthalocyanine pigment concentration, about .1 to about 10 weight percent of at least one desensitizing dye of the formula (X)m Y (2) n ~--.
. . .
. .
~1~397Z
wherein X and Z are independently selected from the group consisting of -NH2 and -NHR;
R is phenyl or phenylsulfonate;
Y is phenyl; and m and n can range from 0 to 2, with the proviso that either m or n is at least l At least a portion of the pigment and desensitizing dye (also hereinafter referred to as "substituted phenazinP compounds") are intimately physically associated with one another, how-ever, the degree of association will vary depending upon the method used in combining these materials. In a prefexred embodiment of this invention the vanadyl phthalocyanine pigment is also "treated" with one or more polymeric materials of the type disclosed in U.S. Patent No. 4,032,339, issued June 28, 1977, either prior or subsequent to "desensit-',: ization" with one or more of the above substituted phenazine compounds.
I 20 In accordance with another aspect of this invention !~ there is provided a photosensitive composition comprising an insulating carrier liquid having dispersed therein from about 0.1 to about lO weight percent vanadyl phthalocyanine , ~ ~ and, a desensitizing effective amount of at least one compound . : :
25~of the~formula: -~N~
(X)m Y (Z)n wherein~X and Z are independently selected : : from the group consisting of -NH2 ; I and -NHR
30 : ; R is phenyl or phenylsulfonate Y is phenyl . m and n can range 0 to 2,,with the : ~proviso that either m or n is at Ieast l ',: ~ , ~
_g_ ., ; .
~ ' .:
~3~7Z
at least a portion of the desensitizing compound present in the composition being intimately associated with at least some of the phthalocyanine pigment present therein.
Substituted phenazine compounds which are preferred in the compositions of the invention include the indulins, pheno-safranine, nigrosine and aniline black. The intimate association of vanadyl phthalocyanine pigments with one or more of the above compounds apparently influences the extent to which photoactivated charge carriers are injected into the medium within which the photoactivated particles are routinely suspended. The precise nature of the physical and/or electrical influence exerted by the compounds on the pigment particle is not known at this time. However, it is hypothesized . , .
' I
9a `' ?~
- ' : ' ' ~ , : ` ,,' ' ~. , ,. ~ ' " , ' ' , 1.11039'~z that the intimate association of such compounds with the pigmen' particle serves to provide recombination centers in which photoinjected holes and electrons are trapped and thus neutralize one another. ~his trapping olf both species of charge carrier has the effect of reducing th~ speed of phc~toe]ectrophoretic response of the vanadyl phthalocyanine pigments and in addition reduces t:he influence that such photoinjected charge can potentially have upon the movement of nonphotoactivated pigment particles also disp~rsed in the same medium as the phthalocyanine pignents. The vanadyl phthalocyanine pi~ments which are desensitized in the manner described above can also be optiondlly treated with other materials such as polymers and/or electron donors or acceptors to further modify the photoelectrophoretic response of the pigment particles.
BRIEF DESCRIPTION OF r'HE DR~WINGS
Fig. l~is a graphical illustration of the photoelectro-phoretic response of the desensitized vanadyl phthalocyanine pigments which are prepared according to the method of this inventio~.
~' DESCRIPTION OF THE INVENTION
INCLUDING PREFERRED EMBODIMENTS
The pho~osensitiv compositions of this invention can be prepared by dispersing vanadyl phthalocyanine in a solvent within which a substituted phenazine compound of the above'formula has been previously dissolved, followed by ball-milling the resultant disperslon for an interval sufficient to promote ~ ' .
_10-i~39'~Z
intimate association of the substit~ted ph~nazine compound with the suspended pigment particlec. The solvent can then he driven off, or preferably, an insulating carrier fluid, such as mineral oil, added to the dispersion and then the resulting dispersion heated in such a manner so as to facilitate the selective evaporation of the polymer solvent.
The above procedure results in the intimate association of at least some of the substituted phena~ine compounds with at least some of the pigment partic'es.
The photosensitive pigment:s of this composition can comprise vanadyl phthalocyanine in any one of its stable forms. The vanadyl phthalocyanine pigment of thi~ composition can be prepared ~y any one of the techniques disclosed in the technical and patent literature, see for example, Moser and Thomas, Phthaloc~anine Compounds, Chapter 3, ACS Monograph Series, Reinhold Publishing Corp., ~ew York (1963).
U.S. Patent No. 3,825,422 (to Gruber and Grushkin) specifically describes the preparation of vanady~ phthalo-cyanine pigments for use in photoelectrophoretic imaging systems. Once having prepared a vanadyl phthalocyanine pigment, the pigment is further refined hy "acid pasting"
in concentrated sul~uric acid or other appropriate acidic medium. Acid pasting generally merely involves dissolving the unrefined vanadyl phthalocyanine pigment in the acidic medium and agitating the resulting solution. The temperature of the acid pasting medium is not allowed to rise to a level which could result in decomposition of the pigment. Subse~uent .
to this acid pasting procedure the pigment is separated from the acidic solution by quenching in water or pouring over i~e - ~11-.
.. . . . ..
~397~
Ma-terials not dissolved during the acid pasting procedure are separated from the acidic solution by filtration prior to quenching with water. The terms "photosensiti~e", "photomigratory", "photoactive" and "photoelectrically active"
are used interchangeably throughout this disclosure to describe the photoelectric properties of the above pigments of the compositions of this invention.
The substituted phenazine compounds of the photosensitive composikions of this invention are preferably soluble in a liquid within which the vanadyl phthalocya~ine is soluble. Most, if not all of the compounds within the scope of the formula previously set forth herein are commercially available or can be prepared by techniques disclosed in the technical literature from readily available starting materials.
In the preferred compositions of this invention, the substituted phenazine compound used in the "treatment"
of vanadyl phthalocyanine pigments are sulfonated indulins.
The preferred composi~ions of this invention contains either one of a combination of the matPrials whose structural formulae are set forth hereinbelow:
.
~0 Nilo38~N ~XM ~ ..
J ~ ~ u_~&~ 503NIl N20 0 . ~aO35--~ ~
n~o ~ ols~ ~ H~503N~ N20 IS~'5~53~ o ' ~r ~:
.
.
.. . . . .
.
~1~3~
As indicated previously most, if not all o~ the pigments and dyes referred to hereinabove are readily commercially available or can be prepared by any one of numerous techniques disclosed in the literature. The preferred dyes whose formulae are set forth hereinabove can be readily prepared by the procedures described by F. Kehrmann et al; his synthesis appearing in Ber., 56, 2394 (1923); Helv. Chim. Acta, 8, 61 (1925); Ber., 46, 3009 (1913~; and Helv. Chim, Acta, 8, 63 (1925). The Kehrmann synthesis is directive for the compounds whose formulae are set forth hereinabove and is, thus, the preferred route for their preparation.
The relative concentration of desensiti~ing dye to pigment particles is a function of the relative efficiency with which such dye is capable of sorption on the pigment and the extent of intended modification of the photoelectric response of the pigment. Generally, the relative concentration of desensitizing dye to pigment can range from about 0.1 to about 10 weight percent. In a preferred embodiment of this invention, the desensitizing dye to pigment concentration is in tke range of from about 1 to about 5 weight percent.
It will be appreciated that certain desensitizing dyes can interact more efficiently with vanadyl phthalocyanine than do others and thus the preferred concentration o desensitizing dye to pigment may vary from one composition to another.
In the oreferred embodiments of this invention, the desensitized pigment is further modified by sorption of polymeric material thereon and/or therein. As indicated previously polymeric material which have been found especially compatible , 39~2 with such desensitized pigments are disclosed in aforementioned U. S. Patent No. 4,Q32,339. Such furtller modification with these polymeric materials can be achieved by simply dispersing the desensitized pigment in a solution of the polymeric materials followed by removal of ~he polymer solvent.
One class of olymeric materials which is especially preferred for use in com~ination with the desensitized pigment is represented by the following formula H H
C - C ~n H Z
wherein Z is a pendant group of the formula ~ or ~
X is a substituent substantially incapable of withdrawing electrons from the electron rich pyridinyl moiety;
m is a whole number from 0 to 3;
and n is a whole number in excess of 25.
The polymeric materials which are associated with 25~ the desensitized plgment can comprise any one or combination of polymer segments having structural units of the formula set forth ~ hereinabove. The vinyl pyridine and substituted vinyl pyridine : monomers embraced by the above formula are generally commercially available, and where unavailable from commercial sources can be rountinely prepared by methbds disclosed in the literature from readily available materials. See, for example, Vinyl and Diene Monomers, Vol. XXIV, part 3, page 1376, Edited by E.C. Leonard, ~ ' ilC~39~
Wiley-Interscicnce Publica~ion, N.Y.~. (].~71). These monomeKs can be l~olymerized by standard free radical ~nd anionic polymerization techni.ques. In the preferred embodi.ments of this invention, the polymeric material comprises poly(2-vinylpyri-dine). The method of association Or the desensitized piqment with the polymer will to some extent li.mit the type of polymers suitable for use in this composition. For example, where the composition is prepared as described previously (solvent sorption of polymer on pigment), the polymer cannot, as a practical matter, be extensively cross-linked without adversely affecting its solubility alld thus its abili.ty to be associated with the pigment. The relative molecular weig~.t of the polymers suitable for use in compositi.ons of this invention does not otherwise appear to be critical. Polymers of 2-vinylpyridine having a number average molecular weight in the range of from about 103 to 106 are suitable for preparation of the compositions of this invention by the above procedures; with polymers of
BACKGROU~D OF THE I~VENTIOl~
Field of the Invention - This invention relates to compositions and methods of use of such compositions. More specifically, this invention is directed to vanadyl phthalo-cyanine/dye compositions and fluid dispersionsthereof. 'rhese fluid dispersions are useful in photoelectro-phoretic imaging processes.
Description o the Prior Art - As is generally recognized in the artt a photoelectrophoreti* imaging system is on~ wherein electrically photosansitive particles dispersed ( in a carrier liquid are initially subtjected to an electric field and either simultaneously or thereafter exposed to aetivating eleetromagn,atic radiation conforming to an image pattern. Photoelectrophoretie imaging techniques may be adapted for the preparation of both monochrDmatic and poly-chromatic reproductions. A detailed disclosure of both the monatchromatic and polyehromatie photoelectrophoretic imaging systems ean be ound in U.S. Patents 3,383,993; 3,384,488;
3,384,565 and 3,384,566. In one of the preferred embodiments of the photoelectrophoretic imaging method deseribed in the above patents, a layer of an imaging suspension eomprising eleetrically photosensitive pigment partieles in an insulating earrier liquid is confined between an injeetin~ eleetrode ~; and a blockint~ electrode (at least one of the eleetrodes being ; 2~ ~at least partially transparent); the photosensitive dispersion s~bjected to an applied eleetrie field; and thereafter exposed ; to aetivating~elqctromagnetic radiation conforming to an image pattern. Typically,~ eomplementary images are formed on the opposing surf'aces of the electrodes whieh are in eontaet with the dispersion of pigment particles. In a monochromatic system, pigment partieles of only one color are required, , : :
X
~,:, . ~ :
11~339~7z however, particles o~ more than one shade of the same color may be utilized if it is desired to provide the capability to produce a range of monochromatic colors. In a polychror,~atic system, images of more than one cGlor, and preferably full color, may be formed by utilizing a plurality of differently colored pigment particles which ideally have spectral response curves which do not substantially overlap each other, thereby providing the necessary color separation. In the preferrecl photoelectrophoretic imaging system re~erred to hereinabove, the pigment particles correspond to the subtractive colors yellow, c~an and magenta, The yellow pigment particles are primaril~ responsive to light with~n the blue region of the electromagnetic spectrum; the cyan particles are primarily photoresponsive to light within the red portion of the electro-magnetic spectrum; and the magenta particles are primarilyresponsive to light within the green portion o~ the electro-magnetic spectrum. Therefore, when a full color reproduction is projected upon a suspension containing these three pigments, the cyan particles will respond to those portions of the ~lage input corresponding to the color red, and upon being photo-activated will migrate from the electrode surface on which the image i5 to he formed thereby leaving beh.~nd the yellow and magenta pigment particles which togethex appear as red~
Similarly, image input corresponding to green light will cause magenta parti~les to migrate and image input corresponding to blue light will cause the yellow particles to migrate.
Where white light imringes upon tre suspension containing , .
~ -4-.. . ...
. ' - .` `
11~39~z the above three pigment particles, all such particles should migrate thereby leaving the surfa~e of the image substantially devoid of pigment. ~le resulting image can thereafter be transferr ~ to a receiving sheet such as white paper and thus the portions of the image which are deficient of pigment will appear as white in the finished copy. In order to obtain good colcr separation, it would be preferable that each pigment migrate only in response t:o activating electromagnetic radiation within its principal region of absorption.
Due to electrical interactic-~s between the pigments and other unknown factors, photosl:imulated particle migration is often incomplete resulting in t~aces of the "subtracted"
pigment remaining at the injectiny electrode thereby imparting undesired color to the image residing on this electrode.
lS As is discussed in the patents previously incorporated by reference, the pigment particles used in photoelectrophoretic imaging systems are initially charged and ca~sed to migrate to the surface of one of two opposing electrodes in response to an electric field established ~etween these electrodes.
Upon absorption of light within i~s principal region of photores~onse, these pigments, it is theorized, generate hole-electron pairs, and depending upon the relative mobility of these charge carriers in the pigment, either one or both of ; ; these charge carriers are injecte~ into the liquid carrier medium. Upon the injection of only one species of carrier ~!:
' `
t in~o the medium, the particle will thereby acquire a net , ~
;~ -5-, , :
~1~39~2 charge wllicll preferably will be identical in sign to the polarity of charge of the electrode to which it had previously migrated. This similarity in charge will cause the pigment particle to be repelled by this formerly attractive electrode resulting in its migration to the surface of the opposing electrode where it forms a complementary image. It will be appreciated thct if the above theoretical explanation is correct, the injection of both species of charge carrier into the liquid caYrier medium will result in a failure to generate the desired ir.lage. Moreover, in the event of indiscriminate injection of charge carriers from the photoactivated pigment into th~ liquid carrier medium and the subseguent transfer of such carriers to a nonphoto-~ activated particle, the non~hotoactivated pigment particle 1 15 will migrate just as if it had absorbed the imaging energy.
This migration of nonphotoactivated particles will seriously impair color separation in the desired reproduction.
It thus appears that in order for good colorseparation to be maintained and faithful reproduction of an original to be achieved, it is necessary to maintain selective electrophotographic response of the pigments to their colors of primary absorption. It is also apparent , .
that this can only be achieved by preventing indiscriminate injection of charge carriers from photoactivated pigments into the liquid carrier medium, The prior art contains frequent reference to various treatment of photoelectrophoretic pigments with i '' `~
:
, ~ :
~lQ39q2 diverse material.s in order to modify or enhance the electro-photographic response of such pigments For example, th~ literature discloses: (a) the adsorption of ~onor and acceptor molecules on pic~
ments utilized in photoelectrophoretic imaging (b) thè inc:'usion of such electrically active materials in the insulating liquid carrier containing such pigment parti~les, or (c) the application of these e lectrically active materials to one of the electrodes used in confii-ing the pigment dispersion.
All of tha above treatments are said to result in charge transfer complex :Eormation between the pigments and these electrically active materials, thereby facilitating injection of electrons from photoactivated p gment particles into the surrounding medium, U,S, Application Serial No, 566, 846, filed July 21, 1966, now abandoned; pub]ished in Japan on March 30, 1970, Application Serial No, 4636667, filed July 20, 1967 Photoactive polymeric materials have also been disclosed as effective in modification of the electrophoretic response of pigment particles used in photoelectrophoretic ~: imaging systems, U,S Application Serial No. 863, 507, file~October 3, 1969, published in Holland on P~pril 6, 1971 as Application Serial No, 70.14614. Poly(N-vinylcarbazole) i5 diselosed in this Dutch patent as useful in the agglomeration - ~ , and/or eneapsulation of ph~tomigratory pigment particles thereby enhancing the electrophotographic response of these particles 25 to imaging energies, Although the prior art systems described above ~ ~ :
~ enable substantia1 enhancement in the photoresponse eharaeter-:~ isties of photomigratory pigment particles used in ph~toe lectro-:: phoretic lmaging, further improvement is still required ::
:~' ,, , . ~ -~.~V3g7Z
especially with regard to the problems associated with color separation and reduction in D
mln It is, therefore, an object of an aspect of this invention to remedy the above, as well as-related deficiencies in the prior art.
More specifically, it is an object of an aspect of this invention to modulate the photoelectric response of certain photomigratory pigments so as to control the indis-criminate injection of charge carriers generated within such pigments from influencing the movement of nonphotoactivated pigments.
An object of an aspect of this invention is to provide a photomigratory pigment composition having improved selective response to activating electromagnetic radiation.
Additional objects of this invention include the use of the above compositions in photoelectrophoretic and photo-immobilization electrophoretic recording systems and methods.
SUM~RY OF THE INVENTION
In accordance with one aspect of this invention there is provided a photosensitive composition comprising an insulating carrier liquid having dispersed therein from about 0.1 to about 10 weight percent vanadyl phthalocyanine pigment and, based upon vanadyl phthalocyanine pigment concentration, about .1 to about 10 weight percent of at least one desensitizing dye of the formula (X)m Y (2) n ~--.
. . .
. .
~1~397Z
wherein X and Z are independently selected from the group consisting of -NH2 and -NHR;
R is phenyl or phenylsulfonate;
Y is phenyl; and m and n can range from 0 to 2, with the proviso that either m or n is at least l At least a portion of the pigment and desensitizing dye (also hereinafter referred to as "substituted phenazinP compounds") are intimately physically associated with one another, how-ever, the degree of association will vary depending upon the method used in combining these materials. In a prefexred embodiment of this invention the vanadyl phthalocyanine pigment is also "treated" with one or more polymeric materials of the type disclosed in U.S. Patent No. 4,032,339, issued June 28, 1977, either prior or subsequent to "desensit-',: ization" with one or more of the above substituted phenazine compounds.
I 20 In accordance with another aspect of this invention !~ there is provided a photosensitive composition comprising an insulating carrier liquid having dispersed therein from about 0.1 to about lO weight percent vanadyl phthalocyanine , ~ ~ and, a desensitizing effective amount of at least one compound . : :
25~of the~formula: -~N~
(X)m Y (Z)n wherein~X and Z are independently selected : : from the group consisting of -NH2 ; I and -NHR
30 : ; R is phenyl or phenylsulfonate Y is phenyl . m and n can range 0 to 2,,with the : ~proviso that either m or n is at Ieast l ',: ~ , ~
_g_ ., ; .
~ ' .:
~3~7Z
at least a portion of the desensitizing compound present in the composition being intimately associated with at least some of the phthalocyanine pigment present therein.
Substituted phenazine compounds which are preferred in the compositions of the invention include the indulins, pheno-safranine, nigrosine and aniline black. The intimate association of vanadyl phthalocyanine pigments with one or more of the above compounds apparently influences the extent to which photoactivated charge carriers are injected into the medium within which the photoactivated particles are routinely suspended. The precise nature of the physical and/or electrical influence exerted by the compounds on the pigment particle is not known at this time. However, it is hypothesized . , .
' I
9a `' ?~
- ' : ' ' ~ , : ` ,,' ' ~. , ,. ~ ' " , ' ' , 1.11039'~z that the intimate association of such compounds with the pigmen' particle serves to provide recombination centers in which photoinjected holes and electrons are trapped and thus neutralize one another. ~his trapping olf both species of charge carrier has the effect of reducing th~ speed of phc~toe]ectrophoretic response of the vanadyl phthalocyanine pigments and in addition reduces t:he influence that such photoinjected charge can potentially have upon the movement of nonphotoactivated pigment particles also disp~rsed in the same medium as the phthalocyanine pignents. The vanadyl phthalocyanine pi~ments which are desensitized in the manner described above can also be optiondlly treated with other materials such as polymers and/or electron donors or acceptors to further modify the photoelectrophoretic response of the pigment particles.
BRIEF DESCRIPTION OF r'HE DR~WINGS
Fig. l~is a graphical illustration of the photoelectro-phoretic response of the desensitized vanadyl phthalocyanine pigments which are prepared according to the method of this inventio~.
~' DESCRIPTION OF THE INVENTION
INCLUDING PREFERRED EMBODIMENTS
The pho~osensitiv compositions of this invention can be prepared by dispersing vanadyl phthalocyanine in a solvent within which a substituted phenazine compound of the above'formula has been previously dissolved, followed by ball-milling the resultant disperslon for an interval sufficient to promote ~ ' .
_10-i~39'~Z
intimate association of the substit~ted ph~nazine compound with the suspended pigment particlec. The solvent can then he driven off, or preferably, an insulating carrier fluid, such as mineral oil, added to the dispersion and then the resulting dispersion heated in such a manner so as to facilitate the selective evaporation of the polymer solvent.
The above procedure results in the intimate association of at least some of the substituted phena~ine compounds with at least some of the pigment partic'es.
The photosensitive pigment:s of this composition can comprise vanadyl phthalocyanine in any one of its stable forms. The vanadyl phthalocyanine pigment of thi~ composition can be prepared ~y any one of the techniques disclosed in the technical and patent literature, see for example, Moser and Thomas, Phthaloc~anine Compounds, Chapter 3, ACS Monograph Series, Reinhold Publishing Corp., ~ew York (1963).
U.S. Patent No. 3,825,422 (to Gruber and Grushkin) specifically describes the preparation of vanady~ phthalo-cyanine pigments for use in photoelectrophoretic imaging systems. Once having prepared a vanadyl phthalocyanine pigment, the pigment is further refined hy "acid pasting"
in concentrated sul~uric acid or other appropriate acidic medium. Acid pasting generally merely involves dissolving the unrefined vanadyl phthalocyanine pigment in the acidic medium and agitating the resulting solution. The temperature of the acid pasting medium is not allowed to rise to a level which could result in decomposition of the pigment. Subse~uent .
to this acid pasting procedure the pigment is separated from the acidic solution by quenching in water or pouring over i~e - ~11-.
.. . . . ..
~397~
Ma-terials not dissolved during the acid pasting procedure are separated from the acidic solution by filtration prior to quenching with water. The terms "photosensiti~e", "photomigratory", "photoactive" and "photoelectrically active"
are used interchangeably throughout this disclosure to describe the photoelectric properties of the above pigments of the compositions of this invention.
The substituted phenazine compounds of the photosensitive composikions of this invention are preferably soluble in a liquid within which the vanadyl phthalocya~ine is soluble. Most, if not all of the compounds within the scope of the formula previously set forth herein are commercially available or can be prepared by techniques disclosed in the technical literature from readily available starting materials.
In the preferred compositions of this invention, the substituted phenazine compound used in the "treatment"
of vanadyl phthalocyanine pigments are sulfonated indulins.
The preferred composi~ions of this invention contains either one of a combination of the matPrials whose structural formulae are set forth hereinbelow:
.
~0 Nilo38~N ~XM ~ ..
J ~ ~ u_~&~ 503NIl N20 0 . ~aO35--~ ~
n~o ~ ols~ ~ H~503N~ N20 IS~'5~53~ o ' ~r ~:
.
.
.. . . . .
.
~1~3~
As indicated previously most, if not all o~ the pigments and dyes referred to hereinabove are readily commercially available or can be prepared by any one of numerous techniques disclosed in the literature. The preferred dyes whose formulae are set forth hereinabove can be readily prepared by the procedures described by F. Kehrmann et al; his synthesis appearing in Ber., 56, 2394 (1923); Helv. Chim. Acta, 8, 61 (1925); Ber., 46, 3009 (1913~; and Helv. Chim, Acta, 8, 63 (1925). The Kehrmann synthesis is directive for the compounds whose formulae are set forth hereinabove and is, thus, the preferred route for their preparation.
The relative concentration of desensiti~ing dye to pigment particles is a function of the relative efficiency with which such dye is capable of sorption on the pigment and the extent of intended modification of the photoelectric response of the pigment. Generally, the relative concentration of desensitizing dye to pigment can range from about 0.1 to about 10 weight percent. In a preferred embodiment of this invention, the desensitizing dye to pigment concentration is in tke range of from about 1 to about 5 weight percent.
It will be appreciated that certain desensitizing dyes can interact more efficiently with vanadyl phthalocyanine than do others and thus the preferred concentration o desensitizing dye to pigment may vary from one composition to another.
In the oreferred embodiments of this invention, the desensitized pigment is further modified by sorption of polymeric material thereon and/or therein. As indicated previously polymeric material which have been found especially compatible , 39~2 with such desensitized pigments are disclosed in aforementioned U. S. Patent No. 4,Q32,339. Such furtller modification with these polymeric materials can be achieved by simply dispersing the desensitized pigment in a solution of the polymeric materials followed by removal of ~he polymer solvent.
One class of olymeric materials which is especially preferred for use in com~ination with the desensitized pigment is represented by the following formula H H
C - C ~n H Z
wherein Z is a pendant group of the formula ~ or ~
X is a substituent substantially incapable of withdrawing electrons from the electron rich pyridinyl moiety;
m is a whole number from 0 to 3;
and n is a whole number in excess of 25.
The polymeric materials which are associated with 25~ the desensitized plgment can comprise any one or combination of polymer segments having structural units of the formula set forth ~ hereinabove. The vinyl pyridine and substituted vinyl pyridine : monomers embraced by the above formula are generally commercially available, and where unavailable from commercial sources can be rountinely prepared by methbds disclosed in the literature from readily available materials. See, for example, Vinyl and Diene Monomers, Vol. XXIV, part 3, page 1376, Edited by E.C. Leonard, ~ ' ilC~39~
Wiley-Interscicnce Publica~ion, N.Y.~. (].~71). These monomeKs can be l~olymerized by standard free radical ~nd anionic polymerization techni.ques. In the preferred embodi.ments of this invention, the polymeric material comprises poly(2-vinylpyri-dine). The method of association Or the desensitized piqment with the polymer will to some extent li.mit the type of polymers suitable for use in this composition. For example, where the composition is prepared as described previously (solvent sorption of polymer on pigment), the polymer cannot, as a practical matter, be extensively cross-linked without adversely affecting its solubility alld thus its abili.ty to be associated with the pigment. The relative molecular weig~.t of the polymers suitable for use in compositi.ons of this invention does not otherwise appear to be critical. Polymers of 2-vinylpyridine having a number average molecular weight in the range of from about 103 to 106 are suitable for preparation of the compositions of this invention by the above procedures; with polymers of
2-vinylpyridine havi.ng a molecular weight in the range of 7000 to 10,000 being preferred. There is, however, an increasing tendency for polymers of 4-vinylpyridine to cross-link as their number average molecular weight exceeds 4000, and thus alternative methods of preparation of the photosensitive composition with this polymer are preferable to that described above. It is understood that any reference herein to the molecular weights of the polymers of this composition is based upon results obtained by gel permeation chromatogxaphy techni~ues using the Q values for polystyrene as a reference. The vinyl pyridine monomers and substituted vinyl pyri.dine monomers corresponding to the above formula can a.lso be randomly copolymerized with a numbex of vinyl llQ397Z
monomers and acrylatc monomers. l~l1e ,tructural units contri-buted to the copolymex by these vinyl and acrylate monomers must of course ~c el~ctrically compatible with the contemplated envi.ronment of use of the resultant materials. That is, the strllCtUral U~litS contribut~d to the resultant copolymers hy thcse monomers must ke substantially incapable of modifi.cation of the electronic i.nteraction of the vinyl pyridine units and substi1~uted vinyl pyridine units of the copolymer with the desensitized vanadyl phthalocyanine pigment. Vinyl monomers which satisfy the above requirements include styrene, alpha methyl styrene, para methyl styrene and 4-isopropyl styrene. Acrylate monomers which satisfy the above requ~rements include n-butyl-methacrylate, methyl methacrylate and ethyl me-thacrylate.
Generally, any one or more of these materials can be copoly-merized with the vinyl pyridine monomers and/or substituted vinyl pyridine described hereinabove in accord with standard free radical and anionic initiated,polymerization techniques.
If desired t:hese same materials can be formed.into block copolymers by standard anionic polymerization techniques. For : , example, one of the monomers of the block copolymer can be initia~ly polymerized under conditions designed to produce an unterminated radical on the polymer segment formed from the flrst monomer. The second monomer can then be added to the charge, whereupon the radical of the,previously polymerized 'material will serve to initiate polymerization of the newly , .
added monom~r and result ln its propagation on the prepoly-merized poly~er segment.
Irrespectivc:of which type of copolymer is formed from the above materials, the mole concentration of struc-: tural units contributed by the vinyl pyridine and/or substituted , -16-.. . - , . .. . . . ...
~103~
vinyl pyridine monomers relative to the structural units con-tributed by the other monomers should generally exceed about 20 and preferably 50 mole percent.
Another class of polymeric materials which is especially preferred for use in combination with the desensi-tized pigment is represented by the formula ~ C - C tm O O - (CH2)n - N~
wherein R is methyl or hydrogen R' and R'' are independently selected from the group consisting of hydrogen, alkyl of 1-10 carbon atoms, phenyl and substituted phenyl, said phenyl substituent being incapable of with-drawing electrons from the electron rich phenyl group;
m is in excess of about 25, and n is in the range of from 1 to 5.
The polymer component of the desensitized pigment dispersion can comprise any one or combination of polymer segments having structural units of the formula as set forth hereinabove. A number of the monomers used in preparation o the polymers having structural units satisfying the above truatural formula are readily commercially available or can be prepared by technigues disclosed in the literature from materials which are readily commercially available. See, for example, Functional Monomers, Vol. II, page 651 et seq.
Edited by R. H. Yokum and E. B. Nyquist, Marcel Depker, Inc.
tl974). In the preferred embodiments of this invention, the polymeric component comprises poly(N,N-dimethylaminoethyl-methacrylate). The monomer used in preparation of this polymer is available from the Rohm and Hass Corporation of Philadelphia.
X
.
}39'72 Such MOnomers can hc polymcrized by frec radical or anionic polymerization tcchniqucs. It is prefcrable in the pr~paration of such polymers to control the~ degree of polymerization so that the number average molecular we~ght (Mn) does no-t exceed about 100,0~0. It is und~rstood that any reference hercin to thc molecular weights of polymers of this composi-tion is based upon results obtained by gel permeation chromatography tech-niques using the Q values for polystyrene as a reference. The molecular weight of such polymers can be readilv controlled by simply ccntrollin~ the relative concen~ration of monomer in the polymerization medium and/or hy the addition of a chain transfer agent to the polymerization medium. In certain instances, the growing radical will behave as a chain transfer agent thereby restricting polymer chain growth to within the preferred range. Benzene is capable of both serving as a solvent for the polymerization of such monomers and effectively controls the molecular weight by acting as a chain transfer agent. The amino alkyl acrylate monomers and substituted amino alkyl acrylate monomers corresponcling to the above formula can also be randomly copolymerized with a number of vinyl monomers and acrylate monomers. The structural units contri-buted to~the copolymer by these vinyl and acrylate monomers must of course be electrically compatible with the contemplated environmen-t of use of the resultant materials. That is, the structural units contributed to the resultant copolymers by these monomers must be substantially incapable of mo~ificatio ' of the electronic relationship of the amino al~yl acrylates ;~ units and substituted amino~alky1 ac~ylate units of the copoly-mer relative to the desensitized pigment. Vinyl monomers which satisfy the above requirements includc styrene, alpha methyl styrene, para methyl styrene and 4-isopropyl styrene.
:
, 11(3397;~
Acryla-te mollomcrs which satisfy the ~bove rcquirements .include n-butylmethacrylatc, methyl methacrylate and ethyl metllacrylate.
Generally, any one or more of these materials can be copoly-merized with the amino a]kyl acrylate monomers and/or substituted amino alkyl acrylate described hereinabovc in accord ~ith standard free radical and anionic ini.tiated polymerization techniques. If desired these same materials can be formed into block copolymers by standard anionic polymerization tech-niques. For example, one of the monomers of the block copolymer can be intilly polymerized under conditions designed to produce an unterminated radical on the polymer segment formed from the fiLst monomer. The second m~nomer can then be added to the charge, whereupon the radi.cal of the previously poly- -merized material will serve to initiate polymerization of the newly added monomer and result in its propagation on the prepolymerized polymer segment.
Irrespective of which type of copolymer is formed from the above materials, the mole concentratlon of structural units~contributed by the amino alkyl acrylate and/or substituted amino alkyl;acrylate monomers relative to the structural units contributed by the other monomers should generally exceed about 20 and preferably 50 mole percent.
: The effective relative concentration of polymer to desensitized pigment particle is a function of the relative eff~icieney with which such polymer is capable of sorption on the desensitized .pigment and the desi.red modification of the photoelectric response of the desensitization pigment. Generally, the re~lative concentration of polymer to desen5itized pigmcnt can range from about 1 to about 20 weight percent. In a pr~ferred ~, :
:~ ~
11~39'72 embodiment of this invontion, the pol~-mer to pigmcnt concentra-tion is in the r~ngc of from about 5 to abc~ut 10 weigl~t percen-t.
It will be appreciated that certain polymers interac-t more efficiently with desensitized vanadyl phthalocyanine than~ do others and t}lus the preferred concentration of polymer to pigment may vary from one composition to another.
The desensitized pigment particles prepared in the manner and from the mat~rials described hereinabove can be dispersed in an insulating carrier liquid and the resulting dispersion used in both photoelectrophore~.ic and photoimmobilization electrophoretic recording systems and methods.
The insulating carrier liquid of this dispersion preferably possesses a resistance of at least 107 ohm-cm or greater.
Materials which satisfy these requirements and which are chemically compatible with the photomigratory pigment composition of this invention include saturated hydrocarbons such as decane, dodecane, N-tetradecane, molten paraffin, molten~beeswax, and other molten thermoplastic materials, Sohio~Odorless Solvent (a kerosene fractlon available from Standàrd Oil~of~Ohlo); Isopar G~(a long chain aliphatic h ~ roo~arbon~avai~lable~from~ Humble Oil Company of ~ew ~e'rsay) and:Klearol~ta~mineral oil product available xom Witco Ch~mical Company of:~ew~York City) are generally pre~erred as~insulating llquid~carrlers;- ~
The photomigratory c~omposi~tion preparad from the~above mater~ials may also be~dispersed in the insulating carr:ier liquid~tQ~ether with at least~ one other Figment having its~pr~lnclpal region:of light absorption substantially outsi.de the~region~of th~ principal region of light absorption of the photomig~ratory~plgment~prepared acc.ording to this invention.
tradc ~ ~
- -., ~ .. .. . . . ... . . . . .
Z
In a preferred embodiment of this invention, the photomigratory composition is dispersed in the insulating carrier liquid together with a magenta colored pigment and a yellow colored pigment. ~he combined pigment concentration in the insulating carrier liquid should preferably be in the range of Erom about 2 ~o about 10 weight percent. In the event that the photomigratory pigment dispersion is to be used in a photoimmobilization electrophoretic recording process of the type described in U.S. ~atent 3,976,485 (to ~roner), the useful range of pigment concentration can be as low as about 0.1 weight percent and preferably range from about ~.1 up to about 0.5 weight percent.
rrhe photomigratory materials of this invention can have a particle size within the range of rrom about 0.1 up to about 3 microns. T7ne relative particle size of such materials in the insulating carrier liquid need not be uniform and in f~ct, a particle size distribution within the previously stated range may provide certain enhanced imaging capabilities.
In a typical photoèlectrophoretic or photoimmobilization electrophoretic recording system, the photomigratory composition/
insulating liquid carrier dispersion is passed through an imaging zone defined by two electrodes; one of which is ;;nominally designated as "the injecting electrode" and che othe~r of which is nominally designated as "the blocking e;lectr~ode." In the cont`ext of this invention, the blocking ele~trode is regarded as an electrode ~hich is substantially incapable of effecting~charge eschange with the photomigratory pigments; whereas, the~iniecting electrode freely exchanges charge with photoactivated photomigratory pigments. In a photo-immobilization e}ectrophoretic recording system, the injecting electrode will be typically coated w~th a dark injecting substance, such as a Lewis acid. The gap hetween the electrades which defines . . . . .
the imaging zone can range from about 10 to about 250 microns.
In order to achieve satisfactory image resolution and density with minimal background, the dielectric strength of the pigment dispersion at the imaging zone r~ust be sufficient to support a field of at least 12 volts/micron; however, in order to achieve imaging capabilities of superior quality, the liquid ~dispersion should be preferably capable of supporting a field of about ~0 volts/micron.
As indicated previously, the intimate association - of desensitizin~ dye with vanadyl phthalocyanine can in some instances affect the efficiency of photoresponse of this pigment. In order to compensate for any loss in electro-photo,graphic speed, such pigments may be optionally doped with s~all quantities (0.05 to about 5 mole percent based on vanadyl phthalocyanin,e concentration) of electron acceptor compounds. Electron acceptor compounds which are suitable for use in compensating for any loss in photosensitivity of vanadyl phthalocyanine pigments include 2,4,7-trinitro-9-fluore~none and~maLo~onitrile der~ivatbves~thereQf. These p;igments may also~be treated with certain polymers ln order to further modify their photoelectrophoretic response.
Typical of such polymers which can be used include poly-ethylene~, poly(utyrene~ and poly(2-vinylpyridine~.
The E'xamp~les which~ol~10~further define, describe and~i}lustrate the;~preparation and use of the desensitized photo-mlgratory pigments prepared acc~ording to the method of this invention.~ Apparatus and techniques used in the preparation and~evaluation of~`such materials are standard as hereinbefore desc;ribed.~ Parts and~percentages appearing in such ExampLes ~` ~ ; are~by~welght unless~stipulated otherwlse.
; ' ~ ' ~ :
~ ~ -22-,: - . : , - , .................. . . - .
. .
~lU397;~
EXAMPLE I
Synthesis of Vanadyl Phthalocyanine - Into a 12 liter flask equipped with a magnetic stirrer and an air condenser are added 247 grams of phthalic anhydride, 247 ~rams of urea, 3 liters of chloronaphthalene and 100 grams of vanadium trichloride. The mixture is heated to boiling under reflux conditions for approximately 45 minutes, cooled to 25C and thereafter filtered. The solids which are re-covered are washed with 300 mls of ethanol, t~en slurried in lOO mls of ethanol for two hours and substantially filtered.
The recovered pigment is thereafter subjected to a series of washes which are carried out at 70C, each ~lash lasting approximately 2 hours: first wash, 2 liters of ~O% sodium hydroxide solution; second wash, 2 liters of 20% hydrochloric acid; and third wash, 2~liters of deionized water. The ~pigment is recovered by filtration, the filter cake allowed to air dry for 24 hours and then dried in a vacuum oven at 65~C. The material produced in the manner which is described above is further~refined by an acid pasting technique which s~described as follows~: ~
About 7.5 grams of unrefined vanadyl phthalocyanlne 9 ~dissolved in 40 mls of concentrated~sulfuric acid and stirrèd for about~50 mlnutes (the temperature of the system being carefully~monitored so as not to permit the solution temperature~to exoeed 3~5~C).~ The~solution i9 then poured hro ~ ~;a~ooars~e fri~ttQd funnel and~soraYed into one liter of ~ ex~which is~mai;tàinedl~at~a tem~erature in the ranae of~ about 18~;to 25C.~ The spray injection o~ the filtrate is~a~ccomplished by~means~of~two concentric glass tubes, so poaltioned~as to~create a~vacuum at the orific~e of the center tube when alr lS forced bet~een the inner and outer walls of 11039~2 the tube. Liquid passing through the center tube is atomized at the orifice by the passage of air between the two walls.
EXAMPL~ II
Preparation of poly(N,N-dimethylaminoethylmeth-acrylate) - About 25 milliliters of N,N-dimethylaminoethylmeth-acrylate (available from Rohm and Haas, Philadelphia, Pa.) and 0.125 grams azobisisobutyronitrile are introduced into a glass lined resin kettle containing 50 milliliters benzene.
The contents of the kettle are then heated to about 65C and maintained at that temperature for about ~6 hours.~ The contents of the kettle are allowed to cool to room temperature, diluted with additional benzene to a total volume of 100 milliliters and freeze dried overn1ght. Yield 20.6 grams white powder, Mw = 113,000; Mn = 32,000; MWD = 3.53 (value obtained by standard GPC echniques based upon an estimated Q value of 41).
E ~ PLE III
Preparation of Poly(2-vinylpyridine) by free radlGa~1 solution;polymerizat1on - Commercia11y available 2-vinylpy~rldine~ obtained~from Reilly Tar and Chemical Co., Indiannapo1is, Indiana) is initially purified by vacuum distillation at 5~Torr and 38C. Azobisisobutyronitrile was~`selected~as~the~free radical inltiator for use in this synth~sis~(available'from Eastman Kodak Co. of Rochester, New~York~
Into~a~3~;neck~10~0~mi~1 round bottom flask equipped with~a~mèchaniGa1 stirre~r;, a~sparging tube and a reflux co~dénser~is~pouréd~45 mls of benzene. The temperature of the~flask~and its~contents~are;~elevated to about 50C and maintained~;~at~this~1eve1 from approximately 2 110urs while the henzene~`Ls~sparged wlth~argon.~ Abou~ 150 mgs (0.75 wei~ht 11~3~72 percent) of azobic.isobutyronitrile are introduced into the flask followed by 20 grams of 2-vinylpyridine. The solution is maintained at 50C for 12 hours under argon and then at 55C for an additional 24 hours. The solution i5 cooled to 35C and diluted with lS0 Mls tetrahydrofuran. The benzene/
tetrahydrofuran/polymer solution is added dropwise to ~ mixture containing approximately 6 pints petroleum ether and 4 pints hexane. The solvent mixture is maintained in a constant state of agitation ~uring the dropwice addition of the polymer solution. The addition of the polymer solution to this solvent quenches the polymerization and resu],ts in Frecipitation of the polymer. The polymer solids are recovered by filtratlon washed with petroleum ether and dried at 70C in an air circulating oven overnight. Yield: 80~ (16 grams) of cream colored polymer are obtained-, Mn = 36K; ~w = 63.8K; MWD = 1.77.
Number average molecular weight and weight average molecular weight analysis by gel permeation chromatography based upon a Q factor of 41.
EXAMPLE IV
Indulin 6B tetrasulfonate (CI 50405) is prepared according,to the procedure described by Solodar and Monahan in Can. J. Chem,, 54, 2902-2914 (1976).~
The procedu~re~ of Example I is repeated, except for the add1tion of about 0.75 grams of Indulin 6B tetrasulfonate to~an~a~queous~dispersl~on of the acid pasted vanadyl phthalocyanine pigment, ~acid paste pigment being disper9ed directly without ;prior~drying). After briefly slurrying these materials together, the solids are separated from the fluid by filtration and dried.
:::
~ 25- ' ~ :
, ~3~
The c1esensitized vanadyl p~-thalocyanille ~igment thus produced can be further modifieci by polymer trea~ment with the material prepared according to ~xample II.
The procedure of part ~ is repeated except that the desensitized vanadyl phthalocyanine pigmen1 is modiEied by polymer treatment wi-th the material prepared according to Example III.
--C--Alternatively, the vanadyl phthalocyanine pigment can be associated with Indulin 6B tetrasulfonate by initially milling dri~d acid pasting vanadyl phthalocyanine pigment in alcohol t~5% absolute alcohol) fo~lowed by dispersal of the pigment in aqueous solutions. The Indulin 6B tetrasulfonate is added to this aqueous pigment dispersion, the materials allowed to interact briefly and the solids separated from the liquid by filtration. The filtrate can be collected and analyzed colometrically to determine the extent of adsorption of dye by -the igment.
-D-I~ yet another alternative procedure, the acid past~dvanadyl phthalocyanine is milled in benzene and benzene/
ethanol solution of the dye added thereto. Milling continues for a relative]y brief interval after wl~ich sufficient mineral oil ~learol, Witco Chemical Co., New York City) is added to the dispersion. The benzene/ethanol fraation is removed ~y selectiv~ evaporation (flash evapora-tion techni~ues and additional mineral oil added to produce a desensitized pigment dispersion in which the pigment concentration is in the range of from ~-lOQ~ by weight.
-26~
., , . ~ . .
-E-In yet another alternative treatment method, the dye can be added directly to the acid solution of pigment during the acid pasting process.
EXAMPLE V
The polymer treated desensitized pigment pre~ared in the manner described in Example IV, Part B, is combined with a mineral oil dispersion of photoelectrically active magenta pigment and a mineral oil dispersion of photoelectrically active yellow pigment. The relative pigment concentrations in the dispersion are approximately l:l:l. The combined pigment concentration in the mineral oi} is in the range o~ from about 8-lO percent by weight.
The imaging qualities of resultant dispersion are evaluated in a photoelectrophoretic imaging mode of the ~ype described in U.S. Patent 3,384,488.
:~ :
The above procedure is repeated with similarly polymer treated vanadyl phthalocyanine pigment which has not u~der~one desensitization. Comparison of images produced by the~respeotives "trimixes" indicates improved green rendition a~d speed conformity within the trimix containing the desen-aipizçd vanadyl phthalocyanine pigment.
Figure~1~i11ustrates the characteristic response aurves~f~desensitized~and non-desensitized (polymer modified) vanadyl~phthalocyanine pigments to red light. The data shows the~desensitized sample to be slower by~a factor of two (20.3 10g~exposure)~at a spe~edpoint of 0.5~DmaX. Under the appropriate~circumstances 1t may prove advantageoUS to mix the s10wer pigment~with~the~faster pigment to arrive at a cyan . ~ . . : : -~1~3g7~
whose photoresponse would thus be pre-isely balanced to other -~
pigments used in conjunction therewith.
It should be apparent from the foregoing disclosure that the substituted phenazene compounds described herein can also be used in conjunction with other pigments in photoelectrophoretic imaging processes and that similar desensitization of the treated pigment will also result.
The above specified embodiments of this invention are merely illustrative of the subject matter described herein and not he interpreted as delineat ng the scope of this invention which is set forth hereinafter in the claims.
.
"
: , . :
, . ~ :~ ' .
,
monomers and acrylatc monomers. l~l1e ,tructural units contri-buted to the copolymex by these vinyl and acrylate monomers must of course ~c el~ctrically compatible with the contemplated envi.ronment of use of the resultant materials. That is, the strllCtUral U~litS contribut~d to the resultant copolymers hy thcse monomers must ke substantially incapable of modifi.cation of the electronic i.nteraction of the vinyl pyridine units and substi1~uted vinyl pyridine units of the copolymer with the desensitized vanadyl phthalocyanine pigment. Vinyl monomers which satisfy the above requirements include styrene, alpha methyl styrene, para methyl styrene and 4-isopropyl styrene. Acrylate monomers which satisfy the above requ~rements include n-butyl-methacrylate, methyl methacrylate and ethyl me-thacrylate.
Generally, any one or more of these materials can be copoly-merized with the vinyl pyridine monomers and/or substituted vinyl pyridine described hereinabove in accord with standard free radical and anionic initiated,polymerization techniques.
If desired t:hese same materials can be formed.into block copolymers by standard anionic polymerization techniques. For : , example, one of the monomers of the block copolymer can be initia~ly polymerized under conditions designed to produce an unterminated radical on the polymer segment formed from the flrst monomer. The second monomer can then be added to the charge, whereupon the radical of the,previously polymerized 'material will serve to initiate polymerization of the newly , .
added monom~r and result ln its propagation on the prepoly-merized poly~er segment.
Irrespectivc:of which type of copolymer is formed from the above materials, the mole concentration of struc-: tural units contributed by the vinyl pyridine and/or substituted , -16-.. . - , . .. . . . ...
~103~
vinyl pyridine monomers relative to the structural units con-tributed by the other monomers should generally exceed about 20 and preferably 50 mole percent.
Another class of polymeric materials which is especially preferred for use in combination with the desensi-tized pigment is represented by the formula ~ C - C tm O O - (CH2)n - N~
wherein R is methyl or hydrogen R' and R'' are independently selected from the group consisting of hydrogen, alkyl of 1-10 carbon atoms, phenyl and substituted phenyl, said phenyl substituent being incapable of with-drawing electrons from the electron rich phenyl group;
m is in excess of about 25, and n is in the range of from 1 to 5.
The polymer component of the desensitized pigment dispersion can comprise any one or combination of polymer segments having structural units of the formula as set forth hereinabove. A number of the monomers used in preparation o the polymers having structural units satisfying the above truatural formula are readily commercially available or can be prepared by technigues disclosed in the literature from materials which are readily commercially available. See, for example, Functional Monomers, Vol. II, page 651 et seq.
Edited by R. H. Yokum and E. B. Nyquist, Marcel Depker, Inc.
tl974). In the preferred embodiments of this invention, the polymeric component comprises poly(N,N-dimethylaminoethyl-methacrylate). The monomer used in preparation of this polymer is available from the Rohm and Hass Corporation of Philadelphia.
X
.
}39'72 Such MOnomers can hc polymcrized by frec radical or anionic polymerization tcchniqucs. It is prefcrable in the pr~paration of such polymers to control the~ degree of polymerization so that the number average molecular we~ght (Mn) does no-t exceed about 100,0~0. It is und~rstood that any reference hercin to thc molecular weights of polymers of this composi-tion is based upon results obtained by gel permeation chromatography tech-niques using the Q values for polystyrene as a reference. The molecular weight of such polymers can be readilv controlled by simply ccntrollin~ the relative concen~ration of monomer in the polymerization medium and/or hy the addition of a chain transfer agent to the polymerization medium. In certain instances, the growing radical will behave as a chain transfer agent thereby restricting polymer chain growth to within the preferred range. Benzene is capable of both serving as a solvent for the polymerization of such monomers and effectively controls the molecular weight by acting as a chain transfer agent. The amino alkyl acrylate monomers and substituted amino alkyl acrylate monomers corresponcling to the above formula can also be randomly copolymerized with a number of vinyl monomers and acrylate monomers. The structural units contri-buted to~the copolymer by these vinyl and acrylate monomers must of course be electrically compatible with the contemplated environmen-t of use of the resultant materials. That is, the structural units contributed to the resultant copolymers by these monomers must be substantially incapable of mo~ificatio ' of the electronic relationship of the amino al~yl acrylates ;~ units and substituted amino~alky1 ac~ylate units of the copoly-mer relative to the desensitized pigment. Vinyl monomers which satisfy the above requirements includc styrene, alpha methyl styrene, para methyl styrene and 4-isopropyl styrene.
:
, 11(3397;~
Acryla-te mollomcrs which satisfy the ~bove rcquirements .include n-butylmethacrylatc, methyl methacrylate and ethyl metllacrylate.
Generally, any one or more of these materials can be copoly-merized with the amino a]kyl acrylate monomers and/or substituted amino alkyl acrylate described hereinabovc in accord ~ith standard free radical and anionic ini.tiated polymerization techniques. If desired these same materials can be formed into block copolymers by standard anionic polymerization tech-niques. For example, one of the monomers of the block copolymer can be intilly polymerized under conditions designed to produce an unterminated radical on the polymer segment formed from the fiLst monomer. The second m~nomer can then be added to the charge, whereupon the radi.cal of the previously poly- -merized material will serve to initiate polymerization of the newly added monomer and result in its propagation on the prepolymerized polymer segment.
Irrespective of which type of copolymer is formed from the above materials, the mole concentratlon of structural units~contributed by the amino alkyl acrylate and/or substituted amino alkyl;acrylate monomers relative to the structural units contributed by the other monomers should generally exceed about 20 and preferably 50 mole percent.
: The effective relative concentration of polymer to desensitized pigment particle is a function of the relative eff~icieney with which such polymer is capable of sorption on the desensitized .pigment and the desi.red modification of the photoelectric response of the desensitization pigment. Generally, the re~lative concentration of polymer to desen5itized pigmcnt can range from about 1 to about 20 weight percent. In a pr~ferred ~, :
:~ ~
11~39'72 embodiment of this invontion, the pol~-mer to pigmcnt concentra-tion is in the r~ngc of from about 5 to abc~ut 10 weigl~t percen-t.
It will be appreciated that certain polymers interac-t more efficiently with desensitized vanadyl phthalocyanine than~ do others and t}lus the preferred concentration of polymer to pigment may vary from one composition to another.
The desensitized pigment particles prepared in the manner and from the mat~rials described hereinabove can be dispersed in an insulating carrier liquid and the resulting dispersion used in both photoelectrophore~.ic and photoimmobilization electrophoretic recording systems and methods.
The insulating carrier liquid of this dispersion preferably possesses a resistance of at least 107 ohm-cm or greater.
Materials which satisfy these requirements and which are chemically compatible with the photomigratory pigment composition of this invention include saturated hydrocarbons such as decane, dodecane, N-tetradecane, molten paraffin, molten~beeswax, and other molten thermoplastic materials, Sohio~Odorless Solvent (a kerosene fractlon available from Standàrd Oil~of~Ohlo); Isopar G~(a long chain aliphatic h ~ roo~arbon~avai~lable~from~ Humble Oil Company of ~ew ~e'rsay) and:Klearol~ta~mineral oil product available xom Witco Ch~mical Company of:~ew~York City) are generally pre~erred as~insulating llquid~carrlers;- ~
The photomigratory c~omposi~tion preparad from the~above mater~ials may also be~dispersed in the insulating carr:ier liquid~tQ~ether with at least~ one other Figment having its~pr~lnclpal region:of light absorption substantially outsi.de the~region~of th~ principal region of light absorption of the photomig~ratory~plgment~prepared acc.ording to this invention.
tradc ~ ~
- -., ~ .. .. . . . ... . . . . .
Z
In a preferred embodiment of this invention, the photomigratory composition is dispersed in the insulating carrier liquid together with a magenta colored pigment and a yellow colored pigment. ~he combined pigment concentration in the insulating carrier liquid should preferably be in the range of Erom about 2 ~o about 10 weight percent. In the event that the photomigratory pigment dispersion is to be used in a photoimmobilization electrophoretic recording process of the type described in U.S. ~atent 3,976,485 (to ~roner), the useful range of pigment concentration can be as low as about 0.1 weight percent and preferably range from about ~.1 up to about 0.5 weight percent.
rrhe photomigratory materials of this invention can have a particle size within the range of rrom about 0.1 up to about 3 microns. T7ne relative particle size of such materials in the insulating carrier liquid need not be uniform and in f~ct, a particle size distribution within the previously stated range may provide certain enhanced imaging capabilities.
In a typical photoèlectrophoretic or photoimmobilization electrophoretic recording system, the photomigratory composition/
insulating liquid carrier dispersion is passed through an imaging zone defined by two electrodes; one of which is ;;nominally designated as "the injecting electrode" and che othe~r of which is nominally designated as "the blocking e;lectr~ode." In the cont`ext of this invention, the blocking ele~trode is regarded as an electrode ~hich is substantially incapable of effecting~charge eschange with the photomigratory pigments; whereas, the~iniecting electrode freely exchanges charge with photoactivated photomigratory pigments. In a photo-immobilization e}ectrophoretic recording system, the injecting electrode will be typically coated w~th a dark injecting substance, such as a Lewis acid. The gap hetween the electrades which defines . . . . .
the imaging zone can range from about 10 to about 250 microns.
In order to achieve satisfactory image resolution and density with minimal background, the dielectric strength of the pigment dispersion at the imaging zone r~ust be sufficient to support a field of at least 12 volts/micron; however, in order to achieve imaging capabilities of superior quality, the liquid ~dispersion should be preferably capable of supporting a field of about ~0 volts/micron.
As indicated previously, the intimate association - of desensitizin~ dye with vanadyl phthalocyanine can in some instances affect the efficiency of photoresponse of this pigment. In order to compensate for any loss in electro-photo,graphic speed, such pigments may be optionally doped with s~all quantities (0.05 to about 5 mole percent based on vanadyl phthalocyanin,e concentration) of electron acceptor compounds. Electron acceptor compounds which are suitable for use in compensating for any loss in photosensitivity of vanadyl phthalocyanine pigments include 2,4,7-trinitro-9-fluore~none and~maLo~onitrile der~ivatbves~thereQf. These p;igments may also~be treated with certain polymers ln order to further modify their photoelectrophoretic response.
Typical of such polymers which can be used include poly-ethylene~, poly(utyrene~ and poly(2-vinylpyridine~.
The E'xamp~les which~ol~10~further define, describe and~i}lustrate the;~preparation and use of the desensitized photo-mlgratory pigments prepared acc~ording to the method of this invention.~ Apparatus and techniques used in the preparation and~evaluation of~`such materials are standard as hereinbefore desc;ribed.~ Parts and~percentages appearing in such ExampLes ~` ~ ; are~by~welght unless~stipulated otherwlse.
; ' ~ ' ~ :
~ ~ -22-,: - . : , - , .................. . . - .
. .
~lU397;~
EXAMPLE I
Synthesis of Vanadyl Phthalocyanine - Into a 12 liter flask equipped with a magnetic stirrer and an air condenser are added 247 grams of phthalic anhydride, 247 ~rams of urea, 3 liters of chloronaphthalene and 100 grams of vanadium trichloride. The mixture is heated to boiling under reflux conditions for approximately 45 minutes, cooled to 25C and thereafter filtered. The solids which are re-covered are washed with 300 mls of ethanol, t~en slurried in lOO mls of ethanol for two hours and substantially filtered.
The recovered pigment is thereafter subjected to a series of washes which are carried out at 70C, each ~lash lasting approximately 2 hours: first wash, 2 liters of ~O% sodium hydroxide solution; second wash, 2 liters of 20% hydrochloric acid; and third wash, 2~liters of deionized water. The ~pigment is recovered by filtration, the filter cake allowed to air dry for 24 hours and then dried in a vacuum oven at 65~C. The material produced in the manner which is described above is further~refined by an acid pasting technique which s~described as follows~: ~
About 7.5 grams of unrefined vanadyl phthalocyanlne 9 ~dissolved in 40 mls of concentrated~sulfuric acid and stirrèd for about~50 mlnutes (the temperature of the system being carefully~monitored so as not to permit the solution temperature~to exoeed 3~5~C).~ The~solution i9 then poured hro ~ ~;a~ooars~e fri~ttQd funnel and~soraYed into one liter of ~ ex~which is~mai;tàinedl~at~a tem~erature in the ranae of~ about 18~;to 25C.~ The spray injection o~ the filtrate is~a~ccomplished by~means~of~two concentric glass tubes, so poaltioned~as to~create a~vacuum at the orific~e of the center tube when alr lS forced bet~een the inner and outer walls of 11039~2 the tube. Liquid passing through the center tube is atomized at the orifice by the passage of air between the two walls.
EXAMPL~ II
Preparation of poly(N,N-dimethylaminoethylmeth-acrylate) - About 25 milliliters of N,N-dimethylaminoethylmeth-acrylate (available from Rohm and Haas, Philadelphia, Pa.) and 0.125 grams azobisisobutyronitrile are introduced into a glass lined resin kettle containing 50 milliliters benzene.
The contents of the kettle are then heated to about 65C and maintained at that temperature for about ~6 hours.~ The contents of the kettle are allowed to cool to room temperature, diluted with additional benzene to a total volume of 100 milliliters and freeze dried overn1ght. Yield 20.6 grams white powder, Mw = 113,000; Mn = 32,000; MWD = 3.53 (value obtained by standard GPC echniques based upon an estimated Q value of 41).
E ~ PLE III
Preparation of Poly(2-vinylpyridine) by free radlGa~1 solution;polymerizat1on - Commercia11y available 2-vinylpy~rldine~ obtained~from Reilly Tar and Chemical Co., Indiannapo1is, Indiana) is initially purified by vacuum distillation at 5~Torr and 38C. Azobisisobutyronitrile was~`selected~as~the~free radical inltiator for use in this synth~sis~(available'from Eastman Kodak Co. of Rochester, New~York~
Into~a~3~;neck~10~0~mi~1 round bottom flask equipped with~a~mèchaniGa1 stirre~r;, a~sparging tube and a reflux co~dénser~is~pouréd~45 mls of benzene. The temperature of the~flask~and its~contents~are;~elevated to about 50C and maintained~;~at~this~1eve1 from approximately 2 110urs while the henzene~`Ls~sparged wlth~argon.~ Abou~ 150 mgs (0.75 wei~ht 11~3~72 percent) of azobic.isobutyronitrile are introduced into the flask followed by 20 grams of 2-vinylpyridine. The solution is maintained at 50C for 12 hours under argon and then at 55C for an additional 24 hours. The solution i5 cooled to 35C and diluted with lS0 Mls tetrahydrofuran. The benzene/
tetrahydrofuran/polymer solution is added dropwise to ~ mixture containing approximately 6 pints petroleum ether and 4 pints hexane. The solvent mixture is maintained in a constant state of agitation ~uring the dropwice addition of the polymer solution. The addition of the polymer solution to this solvent quenches the polymerization and resu],ts in Frecipitation of the polymer. The polymer solids are recovered by filtratlon washed with petroleum ether and dried at 70C in an air circulating oven overnight. Yield: 80~ (16 grams) of cream colored polymer are obtained-, Mn = 36K; ~w = 63.8K; MWD = 1.77.
Number average molecular weight and weight average molecular weight analysis by gel permeation chromatography based upon a Q factor of 41.
EXAMPLE IV
Indulin 6B tetrasulfonate (CI 50405) is prepared according,to the procedure described by Solodar and Monahan in Can. J. Chem,, 54, 2902-2914 (1976).~
The procedu~re~ of Example I is repeated, except for the add1tion of about 0.75 grams of Indulin 6B tetrasulfonate to~an~a~queous~dispersl~on of the acid pasted vanadyl phthalocyanine pigment, ~acid paste pigment being disper9ed directly without ;prior~drying). After briefly slurrying these materials together, the solids are separated from the fluid by filtration and dried.
:::
~ 25- ' ~ :
, ~3~
The c1esensitized vanadyl p~-thalocyanille ~igment thus produced can be further modifieci by polymer trea~ment with the material prepared according to ~xample II.
The procedure of part ~ is repeated except that the desensitized vanadyl phthalocyanine pigmen1 is modiEied by polymer treatment wi-th the material prepared according to Example III.
--C--Alternatively, the vanadyl phthalocyanine pigment can be associated with Indulin 6B tetrasulfonate by initially milling dri~d acid pasting vanadyl phthalocyanine pigment in alcohol t~5% absolute alcohol) fo~lowed by dispersal of the pigment in aqueous solutions. The Indulin 6B tetrasulfonate is added to this aqueous pigment dispersion, the materials allowed to interact briefly and the solids separated from the liquid by filtration. The filtrate can be collected and analyzed colometrically to determine the extent of adsorption of dye by -the igment.
-D-I~ yet another alternative procedure, the acid past~dvanadyl phthalocyanine is milled in benzene and benzene/
ethanol solution of the dye added thereto. Milling continues for a relative]y brief interval after wl~ich sufficient mineral oil ~learol, Witco Chemical Co., New York City) is added to the dispersion. The benzene/ethanol fraation is removed ~y selectiv~ evaporation (flash evapora-tion techni~ues and additional mineral oil added to produce a desensitized pigment dispersion in which the pigment concentration is in the range of from ~-lOQ~ by weight.
-26~
., , . ~ . .
-E-In yet another alternative treatment method, the dye can be added directly to the acid solution of pigment during the acid pasting process.
EXAMPLE V
The polymer treated desensitized pigment pre~ared in the manner described in Example IV, Part B, is combined with a mineral oil dispersion of photoelectrically active magenta pigment and a mineral oil dispersion of photoelectrically active yellow pigment. The relative pigment concentrations in the dispersion are approximately l:l:l. The combined pigment concentration in the mineral oi} is in the range o~ from about 8-lO percent by weight.
The imaging qualities of resultant dispersion are evaluated in a photoelectrophoretic imaging mode of the ~ype described in U.S. Patent 3,384,488.
:~ :
The above procedure is repeated with similarly polymer treated vanadyl phthalocyanine pigment which has not u~der~one desensitization. Comparison of images produced by the~respeotives "trimixes" indicates improved green rendition a~d speed conformity within the trimix containing the desen-aipizçd vanadyl phthalocyanine pigment.
Figure~1~i11ustrates the characteristic response aurves~f~desensitized~and non-desensitized (polymer modified) vanadyl~phthalocyanine pigments to red light. The data shows the~desensitized sample to be slower by~a factor of two (20.3 10g~exposure)~at a spe~edpoint of 0.5~DmaX. Under the appropriate~circumstances 1t may prove advantageoUS to mix the s10wer pigment~with~the~faster pigment to arrive at a cyan . ~ . . : : -~1~3g7~
whose photoresponse would thus be pre-isely balanced to other -~
pigments used in conjunction therewith.
It should be apparent from the foregoing disclosure that the substituted phenazene compounds described herein can also be used in conjunction with other pigments in photoelectrophoretic imaging processes and that similar desensitization of the treated pigment will also result.
The above specified embodiments of this invention are merely illustrative of the subject matter described herein and not he interpreted as delineat ng the scope of this invention which is set forth hereinafter in the claims.
.
"
: , . :
, . ~ :~ ' .
,
Claims (16)
1. A photosensitive composition comprising an insulating carrier liquid having dispersed therein from about 0.1 to about 10 weight percent vanadyl phthalocyanine and, based upon vanadyl phthalocyanine pigment concentration, about .1 to about 10 weight percent of at least one desensitizing dye of the formula:
wherein X and Z are independently selected from the group consisting of -NH2 and -NHR
R is phenyl or phenylsulfonate Y is phenyl m and n can range 0 to 2, with the proviso that either m or n is at least 1 at least a portion of the desensitizing dye present in the composition being intimately associated with at least some of the phthalocyanine pigment present therein.
wherein X and Z are independently selected from the group consisting of -NH2 and -NHR
R is phenyl or phenylsulfonate Y is phenyl m and n can range 0 to 2, with the proviso that either m or n is at least 1 at least a portion of the desensitizing dye present in the composition being intimately associated with at least some of the phthalocyanine pigment present therein.
2. The photosensitive composition of Claim 1, wherein the desensitizing dye is indulin or an acid salt thereof.
3. The photosensitive composition of Claim 1, wherein the desensitizing dye is phenosafranine.
4. The photosensitive composition of Claim 1, wherein the desensitizing dye is nigrosine.
5. The photosensitive composition of Claim 1, wherein the desensitizing dye is aniline black.
6. A photosensitive composition comprising an insulating carrier liquid having dispersed therein from about 0.1 to about 10 weight percent vanadyl phthalocyanine and, a desensitizing effective amount of at least one compound of the formula:
werein X and Z are independently selected from the group consisting of -NH2 and -NHR
R is phenyl or phenylsulfonate Y is phenyl m and n can range 0 to 2, with the proviso that either m or n is at least 1 at least a portion of the desensitizing compound present in the composition being intimately associated with at least some of the phthalocyanine pigment present therein.
werein X and Z are independently selected from the group consisting of -NH2 and -NHR
R is phenyl or phenylsulfonate Y is phenyl m and n can range 0 to 2, with the proviso that either m or n is at least 1 at least a portion of the desensitizing compound present in the composition being intimately associated with at least some of the phthalocyanine pigment present therein.
7. The photosensitive composition of Claim 6, wherein the desensitizing compound is indulin or an acid salt thereof.
8. The photosensitive composition of Claim 6, wherein the desensitizing compound is phenosafranine.
9. The photosensitive composition of Claim 6, wherein the desensitizing compound is nigrosine.
10. The photosensitive composition of Claim 6, wherein the desensitizing compound is aniline black.
11. The photosensitive composition of Claim 1, wherein the vanadyl phthalocyanine pigment is further modified by polymer treatment with a polymeric material having structural units of the formula wherein Z is a pendant group of the formula or X is a substituent substantially incapable of withdrawing electrons from the electron rich pyridinyl moiety;
m is a whole number from 0 to 3;
and n is a whole number in excess of 25.
m is a whole number from 0 to 3;
and n is a whole number in excess of 25.
12. The photosensitive composition of Claim 11, wherein the vanadyl phthalocyanine pigment is further modified by polymer treatment with polymeric material having 2-vinylpyridine structural units.
13. The photosensitive composition of Claim 11, wherein the vanadyl phthalocyanine pigment is further modified by polymer treatment with a polymeric material having structural units of the formula wherein R is methyl or hydrogen R' and R'' are independently selected from the group consisting of hydrogen, alkyl of 1-10 carbon atoms, phenyl and substituted phenyl, said phenyl substituent being incapable of with-drawing electrons from the electron rich phenyl group;
m is in excess of about 25, and n is in the range of from 1 to 5.
m is in excess of about 25, and n is in the range of from 1 to 5.
14. The photosensitive composition of Claim 6, wherein the vanadyl phthalocyanine pigment is further modified by polymer treatment with a polymeric material having structural units of the formula wherein Z is a pendant group of the formula or X is a substituent substantially incapable of withdrawing electrons from the electron rich pyridinyl moiety;
m is a hole number from 0 to 3;
and n is a whole number in excess of 25.
m is a hole number from 0 to 3;
and n is a whole number in excess of 25.
15. The photosensitive composition of Claim 14, wherein the vanadyl phthalocyanine pigment is further modified by polymer treatment with polymeric material having 2-vinylpyridine structural units.
16. The photosensitive composition of Claim 6 wherein the vanadyl phthalocyanine pigment is further modified by polymer treatment with a polymeric material having structural units of the formula wherein R is methyl or hydrogen R' and R'' are independently selected from the group consisting of hydrogen, alkyl of 1-10 carbon atoms, phenyl and substituted phenyl, said phenyl substituent being incapable of with-drawing electrons from the electron rich phenyl group;
m is in excess of about 25, and n is in the range of from 1 to 5.
m is in excess of about 25, and n is in the range of from 1 to 5.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US73535476A | 1976-10-26 | 1976-10-26 | |
| US735,354 | 1976-10-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1103972A true CA1103972A (en) | 1981-06-30 |
Family
ID=24955410
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA289,286A Expired CA1103972A (en) | 1976-10-26 | 1977-10-21 | Photosensitive compositions containing vanadyl phthalocyanine and a phenzine desensitizing dye |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1103972A (en) |
-
1977
- 1977-10-21 CA CA289,286A patent/CA1103972A/en not_active Expired
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