CA2123281A1 - Colored composition mutable by ultraviolet radiation - Google Patents
Colored composition mutable by ultraviolet radiationInfo
- Publication number
- CA2123281A1 CA2123281A1 CA 2123281 CA2123281A CA2123281A1 CA 2123281 A1 CA2123281 A1 CA 2123281A1 CA 2123281 CA2123281 CA 2123281 CA 2123281 A CA2123281 A CA 2123281A CA 2123281 A1 CA2123281 A1 CA 2123281A1
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- Prior art keywords
- ultraviolet radiation
- colorant
- transorber
- colored composition
- molecular includant
- Prior art date
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Abstract
Abstract of the Disclosure A colored composition which includes a colorant, an ultraviolet radiation transorber, and a molecular includant having a chemical structure which defines at least one cavity. Each of the colorant and ultraviolet radiation transorber is associated with the molecular includant. In some embodiments, the colorant is at least partially included within a cavity of the molecular includant and the ultraviolet radiation transorber is associated with the molecular includant outside of the cavity, e.g., the ultraviolet radiation transorber is covalently coupled to the molecular includant. The colorant, in the presence of the ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable. The ultraviolet radiation transorber is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible mutation of the colorant. By way of ex-ample, the colored composition can be incorporated into a toner adapted to be utilized in an electrophotographic process. The toner includes the colorant, ultraviolet radiation transorber, and molecular includant as just described, and a carrier. The carrier can be a polymer, and the toner may contain a charge carrier. The ultraviolet radiation in general will have wavelengths of from about 100 to about 375 nanometers. Especially useful ultraviolet radiation is incoherent, pulsed ultraviolet radiation produced by a dielectric barrier discharge excimer lamp.
Description
-- 21232~
- COLORED COMPOSITION MUl ABLE
BY ULTRAVIOLET R~DIAlION
Backgroulld of the Invention The present invention relates to a colored composition, which in some embodiments may be employed in an electrophotographic toner, e.g., a toner employed in a photocopier which is based on transfer xerography.
Electrophotography is broadly defined as a process in which photons are captured to create an electr~cal image analogue of the original. The electrical analogue in turn is manipulated through a number of steps which result in a physical image. The most commonly used form of electrophotography presently in use is called transfer xerography. Although first demonstrated by C. Carlson in 1938, the process was slow to gain acceptance. Today, however, transfer xerography is the foundation of a multibillion dollar industry.
The heart of the process is a photoreceptor, usually the moving element of the process, which is typically either drum-shaped or a continuous, seamless belt. A corona discharge device deposits gas ions on the photoreceptor surface. The ions provide a uniform electric field across the photoreceptor and a uniform charge layer on its surface. An image of an illuminated original is projected through a lens system and focused on the photoreceptor. Light striking the charged photoreceptor surface results in increased conductivity ~ ~ "
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acr~ss the photoreceptor with the concomitant neutralization of surface charges.Unilluminated regions of the photoreceptor surface retain their charges. The resulting pattern of surface charges is the latent electrostatic image.
A thermoplastic pigmented powder or toner, the particles of which bear 5 a charge opposite to the surface charges on the photoreceptor, is brought close to the photoreceptor, thereby permitting toner particles to be attracted to the charged regions on the photoreceptor surface. The result is a physical image on the photoreceptor surface consisting of electrostatically held toner particles.
A sheet of plain paper is brought into physical contact with the toner-10 bearing photoreceptor. A charge applied to the back side of the paper inducesthe attraction of the toner image to the paper. The image is a positive image of the original. The paper then is stripped from the photoreceptor, with the toner image clinging to it by electrostatic attraction. The toner image is permanently fused to the paper by an appropriate heating means, such as a hot 15 pressure roll or a radiant heater.
Because there is incomplete transfer of toner to the paper, it is necessary to clean the photoreceptor surface of residual toner. Such toner is wiped off with a brush, cloth, or blade. A corona discharge or reverse polarity aids in the removal of toner. A uniform light source then floods the 20 photoreceptor to neutralize any residual charges from the previous image cycle, erasing the previous electrostatic image completely and conditioning the photoreceptor surface for another cycle.
The toner generally consists of 1-15 micrometer average diameter partides of a thermoplastic powder. Black toner typically contains 5-10 25 percent by weight of carbon black particles of less than 1 micrometer dispersed in the thermoplastic powder. For toners employed in color xerography, the carbon black may be replaced with cyan, magenta, or yellow pigments. The concentration and dispersion of the pigment must be adjusted to impart a conductivity to the toner which is appropriate for the development system. For - 21232~:~
most development processes, the toner is required to retain for extended periods of time the charge applied by contact electrification. The therrnoplastic employed in the toner in general is selected on the basis of its melting behavior. The thermoplastic must melt over a relatively narrow temperature 5 range, yet be stable during storage and able to withstand the vigvrous agitation which occurs in xerographic development chambers.
The success of electrophotography, and transfer xerography in particular, no doubt is a significant factor in the efficient distribution of information which has become essential in a global setting. It also contributes 10 to the generation of mountains of paper which ultimately must either be disposed of or ~ecycled. While paper is recycled, it presently is converted to pulp and treated to remove ink, toner, and other colored materials, i.e., deinked, an expensive and not always completely successful operation.
Moreover, deinking results in a sludge which typically is disposed of in a 15 landfill. The resulting deinked pulp then is used, often with the addition of at least some virgin pulp, to form paper, cardboard, cellulosic packaging materials, and the like.
The simplest form of recycling, however, is to reuse the paper intact, thus eliminating the need to repulp. To this end, toners for copier machines 20 have been reported which are rendered colorlcss on exposure to near infrared or infrared radiation. Although the spectrum of sunlight ends at about 375 nanometers, it has a significant infrared component. Hence, such toners have a salient disadvantage in that they are transitory in the presence of such environmental factors as sunlight and heat; that is, such toners become 25 colorless. This result is unsatisfactory because the documents can be rendered illegible before their function or purpose has ended. Accordingly, there is a need for toners for copy machines which will permit the recycling of paper intact, but which are stable to normally encountered environmental factors.
21232~.
- Summary of the In~ention It is an object of the present invention to provide a colored composition which is adapted to become colorless upon exposure to ultraviolet radiation.
S This and other objects will be apparent to those having ordinary skill in the art from a consideration of the specification and claims which follow.
Accordingly, the present invention provides a colored composition which includes:
(A) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable;
(B~ an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible mutation of the colorant; and (C) a molecular includant, with which each of the colorant and ultraviolet radiation transorber is associated.
The present invention also provides a colored composition adapted to be utilized as a toner in an electrophotographic process, which composition includes:
(A) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radialion, to be mutable;
(B) an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible mutation of the colorant;
(C) a molecular includant, with which each of the colorant and ultraviolet radiation transorber is associated; and (D) a carrier for the colorant, ultraviolet radiation transorber, and molecular includant.
~ 2123'~ ' - The present invention additionally provides a method of mutating a colored composition which includes:
(A) providing a molecular, with which a colorant and an ultraviolet radiation transorber is associated; in which S (1) the colorant, in the presence of the ultraviolet radiation tran- .
sorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; and (2) the ultraviolet radiation transorber is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible mutation of the colorant;
and ~:~
(B) irradiating the colored composition with ultraviolet radiation at a dosage level sufficient to irreversibly mutate the colorant.
The present invention further provides an electrophotographic process 15 which includes:
(A) creating an image of a pattern on a photoreceptor surface;
(B) applying a toner to the photoreceptor surface to form a toner image which replicates the pattern;
(C) transferring the toner image to a substrate; and (D) fixing the toner image to the substrate; ~ ~:
in which the toner includes a colorant, an ultraviolet radiation transorber, a molecular indudant, and a carrier as already described.
The present invention still further provides an electrophotographic process which includes:
(A) providing a substrate having a first pattern thereon which is formed by a first toner which includes:
(1) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; ~ `
' .
- ` 212~2~
(2) an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible muhtion of the colorant;
(3~ a molecular includant, with which each of the colorant and S ultraviolet radiation transorber is associated; and (4) a carrier for the colorant and the ultraviolet radiation transorber;
(B) exposing the first pattern on the substrate to ultraviolet radiation at a dosage level sufflcient to irreversibly mutate the colorant;
(C) creating an image of a second pattern on a photoreceptor surface;
(D) applying a second toner to the photoreceptor surface to form a toner image which replicates the second pattern;
(E) transferring the second toner image of the second pattern to the substrate; and (E;) fixing the second toner image to the substrate.
If desired, the second toner can be similar to the first toner.
In certain embodiments, the ultraviolet radiation will have a wavelength in the range of from about 100 to about 400 nanometers. In other embodi-ments, the ultraviolet radiation is incoherent, pulsed ultraviolet radiation from a dielectric barrier discharge excimer lamp.
Detailed Desc~iption of the InYention The term "composition" and such variations as "colored composition"
are used herein to mean a colorant, an ultraviolet radiation transorber, and a molecular includant. When reference is being made to a colored composition which is adapted for a specific application, such as a toner to be used in an electrophotographic process, the term "composition-based" is used as a - ::
~ - 2~232~ ' modifier to indicate that the material, e.g., a toner, includes a colorant, an ultraviolet radiation transorber, and a molecular includant.
As used herein, the term "colorant" is meant to include, without limitation, any material which, in the presence of an ultraviolet radiation 5 transorber, is adapted upon exposure to ultraviolet radiation to be mutable. As a practical matter, the colorant typically will be an organic material, such as an organic dye or pigment, including toners and lakes. Desirably, the colorant -will be substantially transparent to, that is, will not significantly interact with, the ultraviolet radiation to which it is exposed. The term is rneant to include a single material or a mixture of two or more materials.
Organic dye classes include, by way of illustration only, triaryl methyl dyes, such as Malachite Green Carbinol base {4-(dimethylamino)-a-[4-(dimethylamino)phenyl]-cY-phenylbenzenemethanol}, Malachite Green Carbinol hydrochloride {N~[[4-(dimethylamino)phenyl]phenylmethylene]-2,5-cyclo-hexyldien-1-ylidene]-N-methylmethanaminium chloride or bis[l2-(dimethyl-amino)phenyl]phenylmethylium chloride}, and Malachite Green oxalate {N-~[[4(dimethylamino)phenyl]phenylmethylenel-2,5-cyclohexyldien- l-ylidene]-N-methylmethanaminium chloride or bis[p-(dimethylamino)phenyl]phenyl-methylium oxalate}; monoazo dyes, such as Cyanine Black, Chrysoidine [Basic Orange 2; 4-(phenylazo)-1,3-benzenediamine monohydrochloride], and ~-Naphthol Orange; thiazine dyes, such as Methylene Green, zinc chloride double salt [3,7-bis(dimethylamino)-6-nitrophenothiazin-5-ium chloride, zinc chloride double salt]; oxazine dyes, such as Lumichrome (7,8-dimethylallox-azine); naphthalimide dyes, such as Lucifer Yellow CH {6-amino-2-[(hydra-zinocarbonyl)amino]-2,3-dihydro-1,3-dioxo-lH-benz[de]isoquinoline-5,8-disulfonic acid dilithium salt}; azine dyes, such as Janus Green B {3-(diethylamino)-7-[[4-(dimethylamino)phenyl]azo]-5-phenylphenazinium chloride}; cyanine dyes, such as Indocyanine Green {Cardio-Green or Fox Green; 2-[7-[1,3-dihydro-1,1-dimethyl-3-(4-sulfobutyl)-2H-benz[e]indol-2-~.
' - 21232~
ylidene]-l ,3,5-heptatrienyl]-1, 1-dimethyl-3-(4-sulfobutyl)-lH-benz[e]indolium hydroxide inner salt sodium salt}; indigo dyes, such as Indigo {Indigo Blue or Vat Blue 1; 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one}; coumarin dyes, such as 7-hydroxy-4-methylcoumarin (4-methylumbel-S liferone); benzimidazole dyes, such as Hoechst 33258 [bisbenzimide or 2'-(4-hydroxyphenyl)-5-(4-methyl-1-piperazinyl)-2,5'-bi-lH-benzimidazole trihydrochloride pentahydrate]; paraquinoidal dyes, such as Hematoxylin {Natural Black 1; 7,1 lb-dihydrobenz[b]indeno[l ,2-d]pyran-3 ,4,6a,9, 10(6H)-pentol}; fluorescein dyes, such as Fluoresceinamine (5-aminofluorescein);
10 diazonium salt dyes, such as Diazo Red RC (Azoic Diazo No. 10 or Fast Red RC salt; 2-methoxy-5-chlorobenzenediazonium chloride, zinc chloride double salt); azoic diazo dyes, such as E;ast Blue BB salt (Azoic Diazo No. 20; 4-benzoylamino-2,5-diethoxybenzene diazonium chloride, zinc chloride double salt); phenylenediamine dyes, such as Disperse Yellow 9 [N-(2,4~initro-15 phenyl)-l,~phenylenediamine or Solvent Orange 53]; disazo dyes, such as Disperse Orange 13 lSolvent Orange 52; 1-phenylazo-4-(4-hydroxyphenylazo)-naphthalene]; anthraquinone dyes, such as Disperse Blue 3 [Celliton Fast Blue FFR; 1-methylamino~(2-hydroxyethylamino)-9,10-anthraquinone], Disperse Blue 14 [Celliton Fast Blue B; l ,4-bis(methylamino)-9, 10-anthraquinonel, and 20 Alizarin Blue Black B (Mordant Black 13); trisazo dyes, such as Direct Blue 71 {Benzo Light Blue FFL or Sirius Light Blue BRR; 3-[(~[(4-[(6-amino-1-hydroxy-3-sulf~2-naphthalenyl)azo]-6-sulfo-l-naphthalenyl)azo]-1-naphtha-lenyl)azo]-l ,5-naphthalenedisulfonic acid tetrasodium salt}; xanthene dyes, such as 2',7'-dichlorofluorescein; proflavine dyes, such as 3,6-diaminoacridine 25 hemisulfate (Proflavine); sulfonaphthalein dyes, such as Cresol Red (Q-cresol-sulfonaphthalein); phthalocyanine dyes, such as Copper Phthalocyanine {Pigment Blue 15; (SP-4-1)-[29H,31H-phthalocyanato(2-)-N29,N3,N3',N32]-copper}; carotenoid dyes, such as trans-B-carotene (Food Orange 5); carminic acid dyes, such as Carmine, the aluminum or calcium-aluminum lake of ~ ---- 2~ ~32~
carminic acid (7-a-D-glucopyranosyl-9,10-dihydro-3,5,6,8-tetrahydroxy-l-methyl-9,10-dioxo-2-anthracenecarboxylic acid); azure dyes, such as Azure A
[3-amino-7-(dimethylamino)phenothiazin-S-ium chloride or 7-(dimethylamino)-3-imino-3H-phenothiazine hydrochloride]; and acridine dyes, such as Acrid-S ine Orange [Basic Orange 14; 3,8-bis(dimethylamino)acridine hydrochloride, zinc chloride double saltl and Acriflavine (Acriflavine neutral; 3,6-diamino-10-methylacridinium chloride mixture with 3,6-acridinediamine).
The term "mutable" with reference to the colorant is used to mean that the absorption maximum of the colorant in the visible region of the electro-10 magnetic spectrum is capable of being mutated or changed by exposure toultraviolet radiation when in the presence of the ultraviolet radiation transorb-er. In general, it is only necessary that such absorption maximum be mutated to an absorption maximum which is different from that of the colorant prior to exposure to the ultraviolet radiation, and that the mutation be irreversible.15 Thus, the new absorption maximum can be within or without the visible region of the electromagnetic spectrum. In other words, the colorant can mutate to a different color or be rendered colorless. The latter, of course, is desirable when the colorant is used in a colored composition adapted to be utilized as a toner in an electrophotographic process which reuses the electrophotographic 20 copy by first rendering the colored composition colorless and then placing a new image thereon.
As used herein, the term "irreversible" means only that the colorant will not revert to its original color when it no longer is exposed to ultraviolet radia-tion. Desirably, the mutated colorant will be stable, i.e., not appreciably 25 adversely affected by radiation nor nally encountered in the environment, such as natural or artificial light and heat. Thus, desirably a colorant rendered colorless will remain colorless indefinitely.
The term "ultraviolet radiation transorber" is used herein to n~ean any material which is adapted to absorb ultraviolet radiation and interact with the - 21232~ ~
colorant to effect the mutation of the colorant. In some embodiments, the ultraviolet radiation transorber may be an organic compound. The term "compound" is intended to include a single material or a mixture of two or more materials. If two or more materials are employed, it is not necessary 5 that all of them absorb ultraviolet radiation of the same wavelength.
While the mechanism of the interaction of the ultraviolet radiation transorber with the colorant is not totally understood, it is believed that it may interact with the colorant in a variety of ways. For exarnple, the ultraviolet radiation transorber, upon absorbing ultraviolet radiation, may be converted to lO one or more free radicals which interact with the colorant. Such free radical-generating compounds typically are hindered ketones, some examples of which are benzildimethyl ketal (available commercially as Irgacure0 651, Ciba-Geigy Corporation, Hawthorne, New York), l-hydroxycyclohexyl phenyl ketone (Irgacure0 SOO), 2-methyl-1-L~(methylthio)phenyl]-2-morpholino-propan-1-one] (Irgacure0 90 7), 2-benzyl-2-dimethylamino- 1 -(4-morpholinophenyl)butan-1-one (Irgacure0 369), and 1-hydroxycyclohexyl phenyl ketone (Irgacure~
184).
Alternatively, the ultraviolet radiation may initiate an electron transfer or reduction-oxidation reaction between the ultraviolet radiation transorber andthe colorant. In this case, the ultraviolet radiation transorber may be Michler's ketone (~dimethylaminophenyl ketone) or benzyl trimethyl stannate. Or, a cationic mechanism may be involved, in which case the ultraviolet radiation transorber could be, for example, bisl~(diphenylsulphonio)phenyl)] sulfide bis(hexafluorophosphate) (I)egacure0 KI85, Ciba-Geigy Corporation, Hawthorne, New York); Cyracure0 UVI-6990 (Ciba-Geigy Corporation), which is a mixture of bis[4-(diphenylsulphonio)phenyl] sulfide bis(hexafluorophosphate) with related monosulphonium hexafluorophosphate salts; and 115-2,4-(cyclopenta-dienyl)[l,2,3,4,5,6-17-(methylethyl)benzene]-iron(II) hexafluorophosphate (Irgacure0 261).
- 10- `~
ti.;: . , , ' ' -` 212328~
- The term "molecular includant" as used herein is intended to mean any substance having a chemical structure which defines at least one cavity. That is, the molecular includant is a cavity-containing structure. As used herein, theterm "CaVity"iS meanttoinclude any opening or space of a size sufficient S to accept at least a portion of one or both of the colora;~ and the ultraviolet radiation transorber. Thus, the cavity can be a tunnel through the molecular includant or a cave-like space in the molecular includant. The cavity can be isolated or independent, or connected to one or more other cavities.
The molecular includant can be inorganic or organic in nature. In 10 certain embodiments, the chemical structure of the molecular includant is adapted to form a molecular inclusion complex. Examples of molecular includants are, by way of illustration only, clathrates or intercalates, zeolites, and cyclodextrins. In some embodiments, the molecular includant is a cyclodextrin.
As already stated, the colorant and the ultraviolet radiation transorber are associated with the molecular includant. The term "associated" in its broadest sense means only that the colorant and the ultraviolet radiation transorber are in close proximity to the molecular includant. For example, the colorant and/or the ultraviolet radiation transorber can be maintained in close 20 proximity to the molecular indudant by hydrogen bonding, van der Waals forces, or the like. Alternatively, either or both of the colorant and the ultraviolet radiation transorber can be covalently bonded to the molecular includant. In certain embodiments, the colorant will be associated with the molecular includant by means of hydrogen bonding and/or van der Waals 25 forces or the like, while the ultraviolet radiation transorber is covalently bonded to the molecular includant. In other embodiments, the colorant is at least partially included within the cavity of the molecular includant.
The term "ultraviolet radiation" is used herein to mean electromagnetic radiation having wavelengths in the range of from about 100 to about 400 .,......... : , .,~
, . - ~; , ... ~ .. . ... : .
- ~ ~1232~
nanometers. Thus, the term includes the regions commonly referred to as ultraviolet and vacuum ultraviolet. The wavelength ranges typically assigned to these two regions are from about 180 to about 400 nanometers and from about lO0 to about 180 nanometers, respectively.
In some embodiments, the molar ratio of ultraviolet radiation transor-ber to colorant generally will be equal to or greater than about 0.5. As a general rule, the more efficient the ultraviolet radiation transorber is in ab-sorbing the ultraviolet radiation and interacting with, i.e., transferring absorbed energy to, the colorant to effect irreversible mutation of the colorant, the lower lO such ratio can be. Current theories of molecular photochemistry suggest that the lower limit to such ratio is 0.5, based on the generation of two free radicals per photon. As a practical matter, however, ratios higher than l are likely to be required, perhaps as high as about lO. However, the present invention is not bound by any specific molar ratio range. The important 15 feature is that the transorber is present in an amount sufficient to effect mutation of the colorant.
As a practical matter, the colorant, ultraviolet radiation transorber, and molecular includant are likely to be solids. However, any or all of such materials can be a liquid. Alternatively, the colored composition can be a 20 liquid, either because one or more of its components is a liquid or, when themolecular includant is organic in nature, a solvent is employed. Suitable sohents include amides, such as N,N-dimethylformamide; sulfoxides, such as dimethylsulfoxide; ketones, such as acetone, methyl ethyl ketone, and methyl butyl ketone; aliphatic and aromatic hydrocarbons, such as hexane, octane, 25 benzene, toluene, and the xylenes; esters, such as ethyl acetate; water; and the like. When the molecular includant is a cyclodextrin, particularly suitable solvents are the amides and sulfoxides.
For some applications, the colored composition of the present invention typically will be uti1ized in particulate form. In other applications, the ;, -:
. ~ . ... ~ - . ,., -~ , . , . : - ~ - . ~ : -,, . : .
-: ~ . ~ ; . ~ . . . , -, .
,.. , .: . . ... ~ , :, : , 21232~
par~icles of the composition should be very small. For example, the particles of a colored composition adapted for use as a toner in an electrophotographic process typically consist of 7-15 micrometer average diameter particles, although smaller or larger particles can be employed. Methods of forming S such particles are well known to those having ordinary skill in the art.
Photochemical processes involve the absorption or light quanta, or photons, by a molecule, e.g., the ultraviolet radiation transorber, to produce a highly reactive electronically excited state. However, the photon energy, which is proportional to the wavelength of the radiation, cannot be absorbed 10 by the molecule unless it matches the energy difference between the unexcited, or original, state and an excited state. Consequently, while the wavelength range of the ultraviolet radiation to which the colored composition is exposed is not directly of concern, at least a portion of the radiation must have wavelengths which will provide the necessary energy to raise the ultraviolet 15 radiation transorber to an energy level which is capable of interacting with the colorant.
It follows, then, that the absorption maximum of the ultraviolet radiation transorber ideally will be matched with the wavelength range of the ultraviolet radiation in order to increase the efficiency of the mutation of the colorant.
20 Such efficiency also will be increased if the wavelength range of the ultraviolet radiation is relatively narrow, with the maximum of the ultraviolet radiation transorber coming within such range. For these reasons, especially suitable ultraviolet radiation has a wavelength of from about 100 to about 375 nanometers. Ultraviolet radiation within this range desirably may be 25 incoherent, pulsed ultraviolet radiation from a dielectric barrier discharge excimer lamp.
The term "incoherent, pulsed ultraviolet radiation" has reference to the radiation produced by a dielectric barrier discharge excimer lamp (referred to hereinafter as "excimer lamp"). Such a lamp is described, for example, by ''.,'. ,.. ',... ,,',.' ,',;'' ,: `~ , ;,, ' ' ~ ,. , -` 212~2~ ~.
U. Kogelschatz, " Silent discharges for the generation of ultraviolet and vacuumultraviolet excimer radiation, " Pure & A~pl. Chem., 62, No. 9, pp. 1667-1674 (1990); and E. Eliasson and U. Kogelschatz, "UV Excimer Radiation from I~ielectric-Barrier Discharges," A~pl. Phys. B, 46, pp. 299-303 (1988).
Excimer lamps were developed originally by ABB Infocom Ltd., Lenzburg, Switzerland. The excimer lamp technology since has been acquired by Haraus Noblelight AG, Hanau, Germany.
The excimer lamp emits radiation having a very narrow bandwidth, i.e., radiation in which the half width is of the order of 5-15 nanometers.
This emitted radiation is incoherent and pulsed, the frequency of the pulses being dependent upon the frequency of the alternating current power supply which typically is in the range of from about 20 to about 300 kHz. An excimer lamp typically is identified or referred to by the wavelength at which the maximum intensity of the radiation occurs, which convention is followed throughout this specification. Thus, in comparison with most other commer-cially useful sources of ultraviolet radiation which typically emit over the entire ultraviolet spectrum and even into the visible region, excimer lamp radiation is essentially monochromatic.
Excimers are unstable molecular complexes which occur only under extreme conditions, such as those temporarily existing in special types of gas discharge. Typical examples are the molecular bonds between two rare gaseous atoms or between a rare gas atom and a halogen atom. Excimer complexes dissociate within less than a microsecond and, while they are dissociating, release their binding energy in the form of ultraviolet radiation.Known excimers in general emit in the range of from about 125 to about 360 nanometers, depending upon the excimer gas mixture.
When the colored composition is adapted to be utilized as a toner in an electrophotographic process, the composition also will contain a car~rier, the nature of which is well known to those having ordinary skill in the art. For ...,, ., ... . ... - ~ . . ... ~.. . ..
:.. : .... - ... ., : ~ : ;. . . .
-` 2~232~
many applications, the carrier will be a polymer, typically a thermosetting or thermoplastic polymer, with the latter being the more common.
Examples of thermoplastic polymers include, by way of illustration only, end-capped polyacetals, such as poly(oxymethylene) or polyformaldehyde, 5 poly(trichloroacetaldehyde), poly(n-valeraldehyde), poly(acetaldehyde), poly(propionaldehyde), and the like; acrylic polymers, such as polya-crylamide, poly(acrylic acid), poly(methacrylic acid), poly(ethyl acrylate), poly(methyl methacrylate), and the like; fluorocarbon polymers, such as poly(tetrafluoroethylene), perfluorinated ethylene-propylene copolymers, 10 ethylene-tetrafluoroethylene copolymers, poly(chlorotrifluoroethylene), ethylene-chlorotrifluoroethylene copolymers, poly(vinylidene fluoride), poly(vinyl fluoride), and the like; epoxy resins, such as the condensation products of epichlorohydrin and bisphenol A; polyamides, such as poly(6 aminocaproic acid) or poly(~-caprolactam), poly(hexamethylene adipamide), 15 poly(hexamethylene sebacamide), poly(ll-aminoundecanoic acid), and the 1-ike; polyaramides, such as poly(imin~l,3-phenyleneiminoisophthaloyl) or polyCm-phenylene isophthalamide), and the like; parylenes, such as poly-~xylylene, poly(chloro-~xylylene), and the like; polyaryl ethers, such as poly(oxy-2,6-dimethyl-1,4-phenylene) orpoly(~phenylene oxide), and the like;
20 polyaryl sulfones, such as poly(oxy-1,4-phenylenesulfonyl-1,4-phenyleneoxy-1 ,4-phenylene-isopropylidene-1 ,4-phenylene), poly(sulfonyl-l ,~phenylene-oxy-1,4-phenyienesulfonyl-4,4'-biphenylene), and the like; polycarbonates, such as poly(bisphenol A) orpoly(carbonyldioxy-1,4-phenyleneisopropylidene-1,4-phenylene), and the like; polyesters, such as poly(ethylene terephthalate), 25 poly(tetramethylene terephthalate), poly(cyclohexylene-1,4~imethylene terephthalate) or poly(oxymethylene-1,4-cyclohexylenemethyleneoxytere-phthaloyl), and the like; polyaryl sulfides, such as poly(l2-phenylene sulfide) or poly(thio-1,4phenylene), and the like; polyimides, such as poly-(pyromellitimido-l,~phenylene), and the like; polyolefins, such as polyethyl--` 2~ 232~:~
ene,~ polypropylene, poly(l-butene), poly(2-butene), poly(l-pentene), poly(2-pentene), poly(3-methyl-1-pentene), poly(4-methyl-1-pentene), 1,2-poly-1,3-butadiene, 1,4-poly-1,3-butadiene, polyisoprene, polychloroprene, polyacrylonitrile, poly(vinyl acetate), poly(vinylidene chloride~, polystyrene, 5 and the like; and copolymers of the foregoing, such as acrylonitrile-butadiene-styrene (ABS) copolymers, styrene-n-butylmethacrylate copolymers, ethylene-vinyl acetate copolymers, and the like.
Some of the more commonly used thermoplastic polymers include styrene-n-butyl methacrylate copolymers, polystyrene, styrene-n-butyl acrylate 10 copolymers, styrene-butadiene copolymers, polycarbonates, poly(methyl methacrylate), poly(vinylidene fluoride), polyarnides (nylon-12), polyethylene, polypropylene, ethylene-vinyl acetate copolymers, and epoxy resins.
Examples of thermosetting polymers include, again by way of - illustration only, alkyd resins, such as phthalic anhydride-g}ycerol resins, maleic acid -glycerol resins, adipic acid-glycerol resins, and phthalic anhydride-pentaerythritol resins; allylic resins, in which such monomers as diallyl phthalate, diallyl isophthalate diallyl maleate, and diallyl chlorendate serve as nonvolatile cross-linldng agents in polyester compounds; amino resins, such as aniline-formaldehyde resins, ethylene urea-formaldehyde resins, dicyandiamide-formaldehyderesins, melamine-formaldehyderesins, sulfonamide-formaldehyde resins, and urea-formaldehyde resins; epoxy resins, such as cross-linked epichlorohydrin-bisphend A resins; phenolic resins, such as phenol-formalde-hyde resins, including Novolacs and resols; and thermosetting polyesters, silicones, and urethanes.
In addition to the colorant, ultraviolet radiation transorber, molecular includant, and optional carrier, the colored composition of the present invention also can contain additional components, depending upon the application for which it is intended. For example, a composition which is to be utilized as a toner in an electrophotographic process also can contain, for 2123.~ ~
" .
example, charge carriers, stabilizers against thermal ox~dation, viscoelastic pro-perties modifiers, cross-linking agents, plasticizers, and the like. For some applications, the charge carrier will be the major component of the toner.
Charge carriers, of course, are well known to those having ordinary skill in 5 the art and typically are polymer-coated metal particles.
The amount or dosage level of ultraviolet radiation in general will be that amount which is necessary to mutate the colorant. The dosage level, in turn, typically is a function of the time of exposure and the intensity or flux of the radiation source which irradiates the colored composition. The latter is 10 effected by the distance of the composition from the source and, depending upon the wavelength range of the ultraviolet radiation, can be effected by the atmosphere between the radiation source and the composition. Accordingly, in some instances it may be appropriate to expose the composition to the radiation in a controlled atmosphere or in a vacuum, although in general 15 neither approach is desired.
The colored composition of the present invention can be utilized on or in any substrate. If the composition is present in a substrate, however, the substrate should be substantially transparent to the ultraviolet radiation whichis employed to mutate the colorant. That is, the ultraviolet radiation will not 20 significantly interact with or be absorbed by the substrate. As a practical matter, the composition typically will be placed on a substrate, with the most common substrate being paper. Other substrates, such as woven and nonwoven webs or fabrics, films, and the like, can be used, however.
When the colored composition is employed as a toner for an electro-25 photographic process, several variations are possible and come within thescope of the present invention. For example, the composition-based toner can be used to form a first image on a virgin paper sheet. The sheet then can be recycled by exposing the sheet to ultraviolet radiation in accordance with the present invention to render the colorant, and, as a consequence, the 'i ',.'~' ,~ ' - ~`''-' :. ~ ' ' "''- . i` ' ', ' ' ' ': ~ ~ ' , . .
-` 21232~
composition, colorless. A second image then can be formed on the sheet.
The second image can be forrned from a standard, known toner, or from a composition-based toner which is either the same as or different from the composition-based toner which was used to form the first image. If a 5 composition-based toner is used to form the second image, the sheet can be recycled again, with the number of cycles being limited by the build-up of now colorless composition on the surface of the paper. However, any subsequent image can be placed on either side of the sheet. That is, it is not required that a second image be formed on the side of the sheet on which the first image 10 was forrned.
In addition, the conversion of the composition-based toner image on the sheet to a colorless form does not have to take place on the sheet. For example, sheets having images formed from composition-based toners can be recyded in the traditional way. In place of the usual deinking step, however, 15 the sheets are exposed to ultraviolet radiation, either before or after beingconven~d to pulp. The colorless toner then simpl9 becomes incorporated into the paper formed from the resulting pulp.
The present invention is further described by the example which follows. Such example, however, is not to be construed as limiting in any 20 way either the spirit or scope of the present invention. In the example, all parts are parts by weight unless stated otherwise.
Example 1 This example describes the preparation of a B-cyclodextrin molecular includant having (1) an ultraviolet radiation transorber covalently bonded to the cyclodextrin outside of the cavity of the cyclodextrin and (2) a colorant associated with the cyclodextrin by means of hydrogen bonds and/or van der Waals forces.
-- 212328:~
A. ~ Friedel-Crafts Acylation of Transorber A 250-ml, three-necked, round-bottomed reaction flask was fitted with a condenser and a pressure-equalizing addition funnel equipped with a nitrogen inlet tube. A magnetic stirring bar was placed in the flask. While being flushed with nitrogen, the flask was charged with 10 g (0.05 mole~ of 1-hydroxycyclohexyl phenyl ketone (Irgacure~ 184, Ciba-Geigy Corporation, Hawthorne, New York), 100 ml of anhydrous tetrahydofuran (Aldrich Chemical Company, Inc., Milwaukee, Wisconsin), and 5 g (0.05 mole) of succinic anhydride (Aldrich). To the condnuously stirred contents of the flask then was added 6.7 g of anhydrous aluminum chloride (Aldrich). The resulting reaction mixture was maintained at about 0C in an ice bath for about one hour, after which the mixture was allowed to warm to ambient temperature for two hours. The reaction mixture then was poured into a mixture of 500 ml of ice water and 100 ml of diethyl ether. The ether layer was removed after the addition of a small amount of sodium chloride to the aqueous phase to aid phase separation. The ether layer was dried over anhydrous magnesium sulfate. The ether was removed under reduced pressure, leaving 12.7 g (87 percent) of a white crystalline powder. The material was shown to be 1-hydroxycyclohexyl ~(2-carboxyethyl)carbonylphenyl ketone by nuclear magnetic resonance analysis.
B. Preparation of Acylated Transorber Acid Chloride A 250-ml round-bottomed flask fitted with a condenser was charged with 12.0 g of l-hydroxycyclohexyl ~(2-carboxyethyl)carbonylphenyl ketone (0.04 mole), 5.95 g (0.05 mole) of thionyl chloride (Alddch), and 50 ml of diethyl ether. The resulting reaction mixture was stirred at 30C for 30 minutes, after which time the solvent was removed under reduced pressure.
The residue, a white solid, was maintained at 0.01 Torr for 30 minutes to remove residual solvent and excess thionyl chloride, leaving ~ 12.1 g - 19 - .' ,.
, 2123,~
(94 percent) of l-hydroxycyclohexyl 4-(2-chloroformylethyl)carbonylphenyl ketone.
C. Covalent Bondin~ of Acylated Transorber to Cyclodextrin A 250-ml, three-necked, round-bottomed reaction flask containing a 5 magnetic stirring bar and fitted with a thermometer, condenser, and pressure-equalizing addition funnel equipped with a nitrogen inlet tube was charged with 10 g (9.8 mmole) of B-cyclodextrin (American Maize-Products Company, Hammond, Indiana), 31.6 g (98 mmoles) of l-hydroxycyclohexyl 4-(2-chloroformylethyl)carbonylphenyl ketone, and 100 ml of N,N-dimethylform-10 amide while being continuously flushed with nitrogen. The reaction mixturewas heated to 50C and 0.5 ml of triethylamine added. The reaction mixture was maintained at 50C for an hour and allowed to cool to ambient tempera-ture. In this preparation, no attempt was made to isolate the product, a B-cyclodextrin to which an ultraviolet radiation transorber had been covalently 15 coupled (referred to hereinafter for convenience as B-cyclodextrin-transorber).
The foregoing procedure was repeated in order to isolate the product of the reaction. At the conclusion of the procedure as described, the reaction mixture was concentrated in a rotary evaporator to roughly 10 percent of the original volume. The residue was poured into ice water to which sodium 20 chloride then was added to force the product out of solution. The resulting precipitate was isolated by filtration and washed with diethyl ether. The solid was dried under reduced pressure to give 24.8 g of a white powder. In a third preparation, the residue remaining in the rotary evaporator was placed on top of an approximately 7.5-cm column containing about 15 g of silica gel. The 25 residue was eluted with N,N-dimethylformamide, with the eluant being monitored by means of Whatman~ Flexible-Backed TLC Plates (Catalog No.
05-713-161, Fisher Scientific, Pittsburgh, Pennsylvania). The eluted product was isolated by evaporating the solvent. The structure of the product was verified by nuclear magnetic resonance analysis.
~12328:1 D. ~ Association of Colorant with Cyçl~dçx~in-Transorber - Preparation of Colored Composition To a solution of 10 g (estimated to be about 3.6 mmole) of B-cyclodex-trin-transorber in 150 ml of N,N-dimethylformamide in a 250-ml round-5 bottomed flask was added at ambient temperature 1.2 g (3.6 mmole) ofMalachite Green oxalate (Aldrich Chemical Company, Inc., Milwaukee, Wisconsin), referred to hereinafter as Colorant A for convenience. The reaction mixture was stirred with a magnetic stirring bar for one hour at ambient temperature. Most of the solvent then was removed in a rotary 10 evaporator and the residue was eluted from a silica gel column as already described. The B-cyclodextrin-transorber Colorant A inclusion complex moved down the column first, cleanly separating from both free Colorant A and B-cyclodextnn-transorber. Eluant containing the complex was collected and solvent removed in a rotary evaporator. The residue was subjected to a 15 reduced pressure of 0.01 Torr to remove residual solvent to yield a blue-green powder.
E. Mutation of Col~e~ Composition The B-cyclodextrin-transorber Colorant A inclusion complex was exposed to ultraviolet radiation from two different lamps, Lamps A and B.
20 Lamp A was a 2æ-nanometer excimer lamp assembly organized in banks of four cylindrical lamps having a length of about 30 cm. The lamps were cooled by circulating water through a centrally located or inner tube of the lamp and, as a consequence, they operated at a relatively low temperature, i.e., about 50C. The power density at the lamp's outer surface typically is 25 in the range of from about 4 to about 20 joules per square meter ~J/m2).
However, such range in reality merely reflects the capabilities of current excimer lamp power supplies; in the future, hiBher power densities may be practical. The distance from the lamp to the sample being irradiated was 4.5 cm. Lamp B was a 50~watt Hanovia medium pressure mercury lamp .. , - ~- . . ~ . . .. : ~ .: - . . . .
2~ 2~281 (Hanovia Lamp Co., Newark, New Jersey). The distance from Lamp B to the sample being irradiated was about 15 cm.
A few drops of an N,N-dimethylformamide solution of the B-cyclodex-trin-transorber Colorant A inclusion complex were placed on a TLC plate and S in a small polyethylene weighing pan. Both samples were exposed to Lamp ~-A and were decolorized (mutated to a colorless state) in 15-20 seconds.
Similar results were obtained with Lamp B in 30 seconds.
A first control sample consisting of a solution of Colorant A and B-cyclodextrin in N,N-dimethylformamide was not decolorized by Lamp A. A
second control sample consisting of Colorant A and l-hydroxycyclohexyl phenyl ketone in N,N-dimethylforrnamide was decolorized by Lamp A within 60 seconds. On standing, however, the color began to reappear within an hour. ~-To evaluate the effect of solvent on decolorization, 50 mg of the B-cyclodextrin-transorber Colorant A inclusion complex was dissolved in 1 ml of solvent. The resulting solution or mixture was placed on a glass micro-scope slide and exposed to Lamp A for 1 minute. The rate of decolorization, i.e., the time to render the sample colorless, was directly proportional to the solubility of the complex in the solvent, as summarized below.
Solvent Solubilityl)ecolorization Time N,N-Dimethylformamide Poor 1 minute Dimethylsulfoxide Soluble ~10 seconds -Acetone Soluble <10 seconds Hexane Insoluble --Ethyl Acetate Poor 1 minute Finally, 10 mg of the B-cyclodextrin-transorber Colorant A inclusion complex were placed on a glass microscope slide and crushed with a pestle.
-` 212328::~
The-resulting powder was exposed to Lamp A for 10 seconds. The powder turned colorless. Similar results were obtained with lamp B, but at a slower rate.
S Example 2 Because of the possibility in ~he preparation of colored composition described in Example 1 for the acylated transorber acid chloride to at least partially occupy the cavity of the cyclodextrin, to the partial or complete exclusion of colorant, a modified preparative procedure was carried out.
Thus, this example describes the preparation of a B-cyclodextrin molecular includant having (1) a colorant at least partially included within the cavity ofthe cyclodextrin and associated therewith by means of hydrogen bonds and/or van der Waals forces and (2) an ultraviolet radiation transorber covalently bonded to the cyclodextrin outside of the cavity of the cyclodextrin.
A. Association of Colorant with a Cyclodextrin To a solution of 10.0 g (9.8 mmole) of B-cyclodextrin in 150 ml of N,N-dimethylforrnamide was added 3.24 g (9.6 mmoles) of Colorant A. The resulting solution was stirred at ambient temperature for one hour. The reaction solution was concentrated under reduced pressure in a rotary evaporator to a volume about one-tenth of the original volume. The residue wa~ passed over a silica gel column as described in Part C of Example 1. The solvent in the eluant was removed under reduced pressure in a rotary evaporator to give 12.4 g of a blue-green powder, B-cyclodextrin Colorant A
inclusion complex. ~ ~-B. Covalent Bondin~ of Acylated Transorber to Cyclodextrin Colorant Inclusion Complex - Prevaration of Colored Composition A 25~ml, three-necked, round-bottomed reaction flask containing a magnetic stirring bar and fitted with a therrnometer, condenser, and pressure-~ ~ 2 .~
equalizing addition funnel equipped with a nitrogen inlet tube was charged with 10 g (9.6 mmole) of B-cyclodextrin Colorant A inclusion complex, 31.6 g (98 mmoles) of l-hydroxycyclohexyl 4-(2-chloroformylethyl)carbonylphenyl ketone prepared as described in Part B of Example l, and 150 ml of N,N-S dimethylformamide while being continuously flushed with nitrogen. Thereaction mixture was heated to 50C and 0.5 ml of triethylamine added. The reaction mixture was maintained at 50C for an hour and allowed to cool to ambient temperature. The reaction mixture then was worked up as described in Part A, above, to give 14.2 g of B-cyclodextrin-transorber Colorant A
10 inclusion complex, a blue-green powder.
C. Mutation of Colored Composition The procedures describe in Part E of Example 1 were repeated with the B-cyclodextrin-transorber Colorant A inclusion complex prepared in part B, above, with essentially the same results.
Having thus described the invention, numerous changes and modifica-tionis hereof will be readily apparent to those having ordinary skill in the artwithout departing from the spirit or scope of the invention.
- COLORED COMPOSITION MUl ABLE
BY ULTRAVIOLET R~DIAlION
Backgroulld of the Invention The present invention relates to a colored composition, which in some embodiments may be employed in an electrophotographic toner, e.g., a toner employed in a photocopier which is based on transfer xerography.
Electrophotography is broadly defined as a process in which photons are captured to create an electr~cal image analogue of the original. The electrical analogue in turn is manipulated through a number of steps which result in a physical image. The most commonly used form of electrophotography presently in use is called transfer xerography. Although first demonstrated by C. Carlson in 1938, the process was slow to gain acceptance. Today, however, transfer xerography is the foundation of a multibillion dollar industry.
The heart of the process is a photoreceptor, usually the moving element of the process, which is typically either drum-shaped or a continuous, seamless belt. A corona discharge device deposits gas ions on the photoreceptor surface. The ions provide a uniform electric field across the photoreceptor and a uniform charge layer on its surface. An image of an illuminated original is projected through a lens system and focused on the photoreceptor. Light striking the charged photoreceptor surface results in increased conductivity ~ ~ "
~s~
- ~ 212~28~
acr~ss the photoreceptor with the concomitant neutralization of surface charges.Unilluminated regions of the photoreceptor surface retain their charges. The resulting pattern of surface charges is the latent electrostatic image.
A thermoplastic pigmented powder or toner, the particles of which bear 5 a charge opposite to the surface charges on the photoreceptor, is brought close to the photoreceptor, thereby permitting toner particles to be attracted to the charged regions on the photoreceptor surface. The result is a physical image on the photoreceptor surface consisting of electrostatically held toner particles.
A sheet of plain paper is brought into physical contact with the toner-10 bearing photoreceptor. A charge applied to the back side of the paper inducesthe attraction of the toner image to the paper. The image is a positive image of the original. The paper then is stripped from the photoreceptor, with the toner image clinging to it by electrostatic attraction. The toner image is permanently fused to the paper by an appropriate heating means, such as a hot 15 pressure roll or a radiant heater.
Because there is incomplete transfer of toner to the paper, it is necessary to clean the photoreceptor surface of residual toner. Such toner is wiped off with a brush, cloth, or blade. A corona discharge or reverse polarity aids in the removal of toner. A uniform light source then floods the 20 photoreceptor to neutralize any residual charges from the previous image cycle, erasing the previous electrostatic image completely and conditioning the photoreceptor surface for another cycle.
The toner generally consists of 1-15 micrometer average diameter partides of a thermoplastic powder. Black toner typically contains 5-10 25 percent by weight of carbon black particles of less than 1 micrometer dispersed in the thermoplastic powder. For toners employed in color xerography, the carbon black may be replaced with cyan, magenta, or yellow pigments. The concentration and dispersion of the pigment must be adjusted to impart a conductivity to the toner which is appropriate for the development system. For - 21232~:~
most development processes, the toner is required to retain for extended periods of time the charge applied by contact electrification. The therrnoplastic employed in the toner in general is selected on the basis of its melting behavior. The thermoplastic must melt over a relatively narrow temperature 5 range, yet be stable during storage and able to withstand the vigvrous agitation which occurs in xerographic development chambers.
The success of electrophotography, and transfer xerography in particular, no doubt is a significant factor in the efficient distribution of information which has become essential in a global setting. It also contributes 10 to the generation of mountains of paper which ultimately must either be disposed of or ~ecycled. While paper is recycled, it presently is converted to pulp and treated to remove ink, toner, and other colored materials, i.e., deinked, an expensive and not always completely successful operation.
Moreover, deinking results in a sludge which typically is disposed of in a 15 landfill. The resulting deinked pulp then is used, often with the addition of at least some virgin pulp, to form paper, cardboard, cellulosic packaging materials, and the like.
The simplest form of recycling, however, is to reuse the paper intact, thus eliminating the need to repulp. To this end, toners for copier machines 20 have been reported which are rendered colorlcss on exposure to near infrared or infrared radiation. Although the spectrum of sunlight ends at about 375 nanometers, it has a significant infrared component. Hence, such toners have a salient disadvantage in that they are transitory in the presence of such environmental factors as sunlight and heat; that is, such toners become 25 colorless. This result is unsatisfactory because the documents can be rendered illegible before their function or purpose has ended. Accordingly, there is a need for toners for copy machines which will permit the recycling of paper intact, but which are stable to normally encountered environmental factors.
21232~.
- Summary of the In~ention It is an object of the present invention to provide a colored composition which is adapted to become colorless upon exposure to ultraviolet radiation.
S This and other objects will be apparent to those having ordinary skill in the art from a consideration of the specification and claims which follow.
Accordingly, the present invention provides a colored composition which includes:
(A) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable;
(B~ an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible mutation of the colorant; and (C) a molecular includant, with which each of the colorant and ultraviolet radiation transorber is associated.
The present invention also provides a colored composition adapted to be utilized as a toner in an electrophotographic process, which composition includes:
(A) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radialion, to be mutable;
(B) an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible mutation of the colorant;
(C) a molecular includant, with which each of the colorant and ultraviolet radiation transorber is associated; and (D) a carrier for the colorant, ultraviolet radiation transorber, and molecular includant.
~ 2123'~ ' - The present invention additionally provides a method of mutating a colored composition which includes:
(A) providing a molecular, with which a colorant and an ultraviolet radiation transorber is associated; in which S (1) the colorant, in the presence of the ultraviolet radiation tran- .
sorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; and (2) the ultraviolet radiation transorber is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible mutation of the colorant;
and ~:~
(B) irradiating the colored composition with ultraviolet radiation at a dosage level sufficient to irreversibly mutate the colorant.
The present invention further provides an electrophotographic process 15 which includes:
(A) creating an image of a pattern on a photoreceptor surface;
(B) applying a toner to the photoreceptor surface to form a toner image which replicates the pattern;
(C) transferring the toner image to a substrate; and (D) fixing the toner image to the substrate; ~ ~:
in which the toner includes a colorant, an ultraviolet radiation transorber, a molecular indudant, and a carrier as already described.
The present invention still further provides an electrophotographic process which includes:
(A) providing a substrate having a first pattern thereon which is formed by a first toner which includes:
(1) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; ~ `
' .
- ` 212~2~
(2) an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with the colorant to effect the irreversible muhtion of the colorant;
(3~ a molecular includant, with which each of the colorant and S ultraviolet radiation transorber is associated; and (4) a carrier for the colorant and the ultraviolet radiation transorber;
(B) exposing the first pattern on the substrate to ultraviolet radiation at a dosage level sufflcient to irreversibly mutate the colorant;
(C) creating an image of a second pattern on a photoreceptor surface;
(D) applying a second toner to the photoreceptor surface to form a toner image which replicates the second pattern;
(E) transferring the second toner image of the second pattern to the substrate; and (E;) fixing the second toner image to the substrate.
If desired, the second toner can be similar to the first toner.
In certain embodiments, the ultraviolet radiation will have a wavelength in the range of from about 100 to about 400 nanometers. In other embodi-ments, the ultraviolet radiation is incoherent, pulsed ultraviolet radiation from a dielectric barrier discharge excimer lamp.
Detailed Desc~iption of the InYention The term "composition" and such variations as "colored composition"
are used herein to mean a colorant, an ultraviolet radiation transorber, and a molecular includant. When reference is being made to a colored composition which is adapted for a specific application, such as a toner to be used in an electrophotographic process, the term "composition-based" is used as a - ::
~ - 2~232~ ' modifier to indicate that the material, e.g., a toner, includes a colorant, an ultraviolet radiation transorber, and a molecular includant.
As used herein, the term "colorant" is meant to include, without limitation, any material which, in the presence of an ultraviolet radiation 5 transorber, is adapted upon exposure to ultraviolet radiation to be mutable. As a practical matter, the colorant typically will be an organic material, such as an organic dye or pigment, including toners and lakes. Desirably, the colorant -will be substantially transparent to, that is, will not significantly interact with, the ultraviolet radiation to which it is exposed. The term is rneant to include a single material or a mixture of two or more materials.
Organic dye classes include, by way of illustration only, triaryl methyl dyes, such as Malachite Green Carbinol base {4-(dimethylamino)-a-[4-(dimethylamino)phenyl]-cY-phenylbenzenemethanol}, Malachite Green Carbinol hydrochloride {N~[[4-(dimethylamino)phenyl]phenylmethylene]-2,5-cyclo-hexyldien-1-ylidene]-N-methylmethanaminium chloride or bis[l2-(dimethyl-amino)phenyl]phenylmethylium chloride}, and Malachite Green oxalate {N-~[[4(dimethylamino)phenyl]phenylmethylenel-2,5-cyclohexyldien- l-ylidene]-N-methylmethanaminium chloride or bis[p-(dimethylamino)phenyl]phenyl-methylium oxalate}; monoazo dyes, such as Cyanine Black, Chrysoidine [Basic Orange 2; 4-(phenylazo)-1,3-benzenediamine monohydrochloride], and ~-Naphthol Orange; thiazine dyes, such as Methylene Green, zinc chloride double salt [3,7-bis(dimethylamino)-6-nitrophenothiazin-5-ium chloride, zinc chloride double salt]; oxazine dyes, such as Lumichrome (7,8-dimethylallox-azine); naphthalimide dyes, such as Lucifer Yellow CH {6-amino-2-[(hydra-zinocarbonyl)amino]-2,3-dihydro-1,3-dioxo-lH-benz[de]isoquinoline-5,8-disulfonic acid dilithium salt}; azine dyes, such as Janus Green B {3-(diethylamino)-7-[[4-(dimethylamino)phenyl]azo]-5-phenylphenazinium chloride}; cyanine dyes, such as Indocyanine Green {Cardio-Green or Fox Green; 2-[7-[1,3-dihydro-1,1-dimethyl-3-(4-sulfobutyl)-2H-benz[e]indol-2-~.
' - 21232~
ylidene]-l ,3,5-heptatrienyl]-1, 1-dimethyl-3-(4-sulfobutyl)-lH-benz[e]indolium hydroxide inner salt sodium salt}; indigo dyes, such as Indigo {Indigo Blue or Vat Blue 1; 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one}; coumarin dyes, such as 7-hydroxy-4-methylcoumarin (4-methylumbel-S liferone); benzimidazole dyes, such as Hoechst 33258 [bisbenzimide or 2'-(4-hydroxyphenyl)-5-(4-methyl-1-piperazinyl)-2,5'-bi-lH-benzimidazole trihydrochloride pentahydrate]; paraquinoidal dyes, such as Hematoxylin {Natural Black 1; 7,1 lb-dihydrobenz[b]indeno[l ,2-d]pyran-3 ,4,6a,9, 10(6H)-pentol}; fluorescein dyes, such as Fluoresceinamine (5-aminofluorescein);
10 diazonium salt dyes, such as Diazo Red RC (Azoic Diazo No. 10 or Fast Red RC salt; 2-methoxy-5-chlorobenzenediazonium chloride, zinc chloride double salt); azoic diazo dyes, such as E;ast Blue BB salt (Azoic Diazo No. 20; 4-benzoylamino-2,5-diethoxybenzene diazonium chloride, zinc chloride double salt); phenylenediamine dyes, such as Disperse Yellow 9 [N-(2,4~initro-15 phenyl)-l,~phenylenediamine or Solvent Orange 53]; disazo dyes, such as Disperse Orange 13 lSolvent Orange 52; 1-phenylazo-4-(4-hydroxyphenylazo)-naphthalene]; anthraquinone dyes, such as Disperse Blue 3 [Celliton Fast Blue FFR; 1-methylamino~(2-hydroxyethylamino)-9,10-anthraquinone], Disperse Blue 14 [Celliton Fast Blue B; l ,4-bis(methylamino)-9, 10-anthraquinonel, and 20 Alizarin Blue Black B (Mordant Black 13); trisazo dyes, such as Direct Blue 71 {Benzo Light Blue FFL or Sirius Light Blue BRR; 3-[(~[(4-[(6-amino-1-hydroxy-3-sulf~2-naphthalenyl)azo]-6-sulfo-l-naphthalenyl)azo]-1-naphtha-lenyl)azo]-l ,5-naphthalenedisulfonic acid tetrasodium salt}; xanthene dyes, such as 2',7'-dichlorofluorescein; proflavine dyes, such as 3,6-diaminoacridine 25 hemisulfate (Proflavine); sulfonaphthalein dyes, such as Cresol Red (Q-cresol-sulfonaphthalein); phthalocyanine dyes, such as Copper Phthalocyanine {Pigment Blue 15; (SP-4-1)-[29H,31H-phthalocyanato(2-)-N29,N3,N3',N32]-copper}; carotenoid dyes, such as trans-B-carotene (Food Orange 5); carminic acid dyes, such as Carmine, the aluminum or calcium-aluminum lake of ~ ---- 2~ ~32~
carminic acid (7-a-D-glucopyranosyl-9,10-dihydro-3,5,6,8-tetrahydroxy-l-methyl-9,10-dioxo-2-anthracenecarboxylic acid); azure dyes, such as Azure A
[3-amino-7-(dimethylamino)phenothiazin-S-ium chloride or 7-(dimethylamino)-3-imino-3H-phenothiazine hydrochloride]; and acridine dyes, such as Acrid-S ine Orange [Basic Orange 14; 3,8-bis(dimethylamino)acridine hydrochloride, zinc chloride double saltl and Acriflavine (Acriflavine neutral; 3,6-diamino-10-methylacridinium chloride mixture with 3,6-acridinediamine).
The term "mutable" with reference to the colorant is used to mean that the absorption maximum of the colorant in the visible region of the electro-10 magnetic spectrum is capable of being mutated or changed by exposure toultraviolet radiation when in the presence of the ultraviolet radiation transorb-er. In general, it is only necessary that such absorption maximum be mutated to an absorption maximum which is different from that of the colorant prior to exposure to the ultraviolet radiation, and that the mutation be irreversible.15 Thus, the new absorption maximum can be within or without the visible region of the electromagnetic spectrum. In other words, the colorant can mutate to a different color or be rendered colorless. The latter, of course, is desirable when the colorant is used in a colored composition adapted to be utilized as a toner in an electrophotographic process which reuses the electrophotographic 20 copy by first rendering the colored composition colorless and then placing a new image thereon.
As used herein, the term "irreversible" means only that the colorant will not revert to its original color when it no longer is exposed to ultraviolet radia-tion. Desirably, the mutated colorant will be stable, i.e., not appreciably 25 adversely affected by radiation nor nally encountered in the environment, such as natural or artificial light and heat. Thus, desirably a colorant rendered colorless will remain colorless indefinitely.
The term "ultraviolet radiation transorber" is used herein to n~ean any material which is adapted to absorb ultraviolet radiation and interact with the - 21232~ ~
colorant to effect the mutation of the colorant. In some embodiments, the ultraviolet radiation transorber may be an organic compound. The term "compound" is intended to include a single material or a mixture of two or more materials. If two or more materials are employed, it is not necessary 5 that all of them absorb ultraviolet radiation of the same wavelength.
While the mechanism of the interaction of the ultraviolet radiation transorber with the colorant is not totally understood, it is believed that it may interact with the colorant in a variety of ways. For exarnple, the ultraviolet radiation transorber, upon absorbing ultraviolet radiation, may be converted to lO one or more free radicals which interact with the colorant. Such free radical-generating compounds typically are hindered ketones, some examples of which are benzildimethyl ketal (available commercially as Irgacure0 651, Ciba-Geigy Corporation, Hawthorne, New York), l-hydroxycyclohexyl phenyl ketone (Irgacure0 SOO), 2-methyl-1-L~(methylthio)phenyl]-2-morpholino-propan-1-one] (Irgacure0 90 7), 2-benzyl-2-dimethylamino- 1 -(4-morpholinophenyl)butan-1-one (Irgacure0 369), and 1-hydroxycyclohexyl phenyl ketone (Irgacure~
184).
Alternatively, the ultraviolet radiation may initiate an electron transfer or reduction-oxidation reaction between the ultraviolet radiation transorber andthe colorant. In this case, the ultraviolet radiation transorber may be Michler's ketone (~dimethylaminophenyl ketone) or benzyl trimethyl stannate. Or, a cationic mechanism may be involved, in which case the ultraviolet radiation transorber could be, for example, bisl~(diphenylsulphonio)phenyl)] sulfide bis(hexafluorophosphate) (I)egacure0 KI85, Ciba-Geigy Corporation, Hawthorne, New York); Cyracure0 UVI-6990 (Ciba-Geigy Corporation), which is a mixture of bis[4-(diphenylsulphonio)phenyl] sulfide bis(hexafluorophosphate) with related monosulphonium hexafluorophosphate salts; and 115-2,4-(cyclopenta-dienyl)[l,2,3,4,5,6-17-(methylethyl)benzene]-iron(II) hexafluorophosphate (Irgacure0 261).
- 10- `~
ti.;: . , , ' ' -` 212328~
- The term "molecular includant" as used herein is intended to mean any substance having a chemical structure which defines at least one cavity. That is, the molecular includant is a cavity-containing structure. As used herein, theterm "CaVity"iS meanttoinclude any opening or space of a size sufficient S to accept at least a portion of one or both of the colora;~ and the ultraviolet radiation transorber. Thus, the cavity can be a tunnel through the molecular includant or a cave-like space in the molecular includant. The cavity can be isolated or independent, or connected to one or more other cavities.
The molecular includant can be inorganic or organic in nature. In 10 certain embodiments, the chemical structure of the molecular includant is adapted to form a molecular inclusion complex. Examples of molecular includants are, by way of illustration only, clathrates or intercalates, zeolites, and cyclodextrins. In some embodiments, the molecular includant is a cyclodextrin.
As already stated, the colorant and the ultraviolet radiation transorber are associated with the molecular includant. The term "associated" in its broadest sense means only that the colorant and the ultraviolet radiation transorber are in close proximity to the molecular includant. For example, the colorant and/or the ultraviolet radiation transorber can be maintained in close 20 proximity to the molecular indudant by hydrogen bonding, van der Waals forces, or the like. Alternatively, either or both of the colorant and the ultraviolet radiation transorber can be covalently bonded to the molecular includant. In certain embodiments, the colorant will be associated with the molecular includant by means of hydrogen bonding and/or van der Waals 25 forces or the like, while the ultraviolet radiation transorber is covalently bonded to the molecular includant. In other embodiments, the colorant is at least partially included within the cavity of the molecular includant.
The term "ultraviolet radiation" is used herein to mean electromagnetic radiation having wavelengths in the range of from about 100 to about 400 .,......... : , .,~
, . - ~; , ... ~ .. . ... : .
- ~ ~1232~
nanometers. Thus, the term includes the regions commonly referred to as ultraviolet and vacuum ultraviolet. The wavelength ranges typically assigned to these two regions are from about 180 to about 400 nanometers and from about lO0 to about 180 nanometers, respectively.
In some embodiments, the molar ratio of ultraviolet radiation transor-ber to colorant generally will be equal to or greater than about 0.5. As a general rule, the more efficient the ultraviolet radiation transorber is in ab-sorbing the ultraviolet radiation and interacting with, i.e., transferring absorbed energy to, the colorant to effect irreversible mutation of the colorant, the lower lO such ratio can be. Current theories of molecular photochemistry suggest that the lower limit to such ratio is 0.5, based on the generation of two free radicals per photon. As a practical matter, however, ratios higher than l are likely to be required, perhaps as high as about lO. However, the present invention is not bound by any specific molar ratio range. The important 15 feature is that the transorber is present in an amount sufficient to effect mutation of the colorant.
As a practical matter, the colorant, ultraviolet radiation transorber, and molecular includant are likely to be solids. However, any or all of such materials can be a liquid. Alternatively, the colored composition can be a 20 liquid, either because one or more of its components is a liquid or, when themolecular includant is organic in nature, a solvent is employed. Suitable sohents include amides, such as N,N-dimethylformamide; sulfoxides, such as dimethylsulfoxide; ketones, such as acetone, methyl ethyl ketone, and methyl butyl ketone; aliphatic and aromatic hydrocarbons, such as hexane, octane, 25 benzene, toluene, and the xylenes; esters, such as ethyl acetate; water; and the like. When the molecular includant is a cyclodextrin, particularly suitable solvents are the amides and sulfoxides.
For some applications, the colored composition of the present invention typically will be uti1ized in particulate form. In other applications, the ;, -:
. ~ . ... ~ - . ,., -~ , . , . : - ~ - . ~ : -,, . : .
-: ~ . ~ ; . ~ . . . , -, .
,.. , .: . . ... ~ , :, : , 21232~
par~icles of the composition should be very small. For example, the particles of a colored composition adapted for use as a toner in an electrophotographic process typically consist of 7-15 micrometer average diameter particles, although smaller or larger particles can be employed. Methods of forming S such particles are well known to those having ordinary skill in the art.
Photochemical processes involve the absorption or light quanta, or photons, by a molecule, e.g., the ultraviolet radiation transorber, to produce a highly reactive electronically excited state. However, the photon energy, which is proportional to the wavelength of the radiation, cannot be absorbed 10 by the molecule unless it matches the energy difference between the unexcited, or original, state and an excited state. Consequently, while the wavelength range of the ultraviolet radiation to which the colored composition is exposed is not directly of concern, at least a portion of the radiation must have wavelengths which will provide the necessary energy to raise the ultraviolet 15 radiation transorber to an energy level which is capable of interacting with the colorant.
It follows, then, that the absorption maximum of the ultraviolet radiation transorber ideally will be matched with the wavelength range of the ultraviolet radiation in order to increase the efficiency of the mutation of the colorant.
20 Such efficiency also will be increased if the wavelength range of the ultraviolet radiation is relatively narrow, with the maximum of the ultraviolet radiation transorber coming within such range. For these reasons, especially suitable ultraviolet radiation has a wavelength of from about 100 to about 375 nanometers. Ultraviolet radiation within this range desirably may be 25 incoherent, pulsed ultraviolet radiation from a dielectric barrier discharge excimer lamp.
The term "incoherent, pulsed ultraviolet radiation" has reference to the radiation produced by a dielectric barrier discharge excimer lamp (referred to hereinafter as "excimer lamp"). Such a lamp is described, for example, by ''.,'. ,.. ',... ,,',.' ,',;'' ,: `~ , ;,, ' ' ~ ,. , -` 212~2~ ~.
U. Kogelschatz, " Silent discharges for the generation of ultraviolet and vacuumultraviolet excimer radiation, " Pure & A~pl. Chem., 62, No. 9, pp. 1667-1674 (1990); and E. Eliasson and U. Kogelschatz, "UV Excimer Radiation from I~ielectric-Barrier Discharges," A~pl. Phys. B, 46, pp. 299-303 (1988).
Excimer lamps were developed originally by ABB Infocom Ltd., Lenzburg, Switzerland. The excimer lamp technology since has been acquired by Haraus Noblelight AG, Hanau, Germany.
The excimer lamp emits radiation having a very narrow bandwidth, i.e., radiation in which the half width is of the order of 5-15 nanometers.
This emitted radiation is incoherent and pulsed, the frequency of the pulses being dependent upon the frequency of the alternating current power supply which typically is in the range of from about 20 to about 300 kHz. An excimer lamp typically is identified or referred to by the wavelength at which the maximum intensity of the radiation occurs, which convention is followed throughout this specification. Thus, in comparison with most other commer-cially useful sources of ultraviolet radiation which typically emit over the entire ultraviolet spectrum and even into the visible region, excimer lamp radiation is essentially monochromatic.
Excimers are unstable molecular complexes which occur only under extreme conditions, such as those temporarily existing in special types of gas discharge. Typical examples are the molecular bonds between two rare gaseous atoms or between a rare gas atom and a halogen atom. Excimer complexes dissociate within less than a microsecond and, while they are dissociating, release their binding energy in the form of ultraviolet radiation.Known excimers in general emit in the range of from about 125 to about 360 nanometers, depending upon the excimer gas mixture.
When the colored composition is adapted to be utilized as a toner in an electrophotographic process, the composition also will contain a car~rier, the nature of which is well known to those having ordinary skill in the art. For ...,, ., ... . ... - ~ . . ... ~.. . ..
:.. : .... - ... ., : ~ : ;. . . .
-` 2~232~
many applications, the carrier will be a polymer, typically a thermosetting or thermoplastic polymer, with the latter being the more common.
Examples of thermoplastic polymers include, by way of illustration only, end-capped polyacetals, such as poly(oxymethylene) or polyformaldehyde, 5 poly(trichloroacetaldehyde), poly(n-valeraldehyde), poly(acetaldehyde), poly(propionaldehyde), and the like; acrylic polymers, such as polya-crylamide, poly(acrylic acid), poly(methacrylic acid), poly(ethyl acrylate), poly(methyl methacrylate), and the like; fluorocarbon polymers, such as poly(tetrafluoroethylene), perfluorinated ethylene-propylene copolymers, 10 ethylene-tetrafluoroethylene copolymers, poly(chlorotrifluoroethylene), ethylene-chlorotrifluoroethylene copolymers, poly(vinylidene fluoride), poly(vinyl fluoride), and the like; epoxy resins, such as the condensation products of epichlorohydrin and bisphenol A; polyamides, such as poly(6 aminocaproic acid) or poly(~-caprolactam), poly(hexamethylene adipamide), 15 poly(hexamethylene sebacamide), poly(ll-aminoundecanoic acid), and the 1-ike; polyaramides, such as poly(imin~l,3-phenyleneiminoisophthaloyl) or polyCm-phenylene isophthalamide), and the like; parylenes, such as poly-~xylylene, poly(chloro-~xylylene), and the like; polyaryl ethers, such as poly(oxy-2,6-dimethyl-1,4-phenylene) orpoly(~phenylene oxide), and the like;
20 polyaryl sulfones, such as poly(oxy-1,4-phenylenesulfonyl-1,4-phenyleneoxy-1 ,4-phenylene-isopropylidene-1 ,4-phenylene), poly(sulfonyl-l ,~phenylene-oxy-1,4-phenyienesulfonyl-4,4'-biphenylene), and the like; polycarbonates, such as poly(bisphenol A) orpoly(carbonyldioxy-1,4-phenyleneisopropylidene-1,4-phenylene), and the like; polyesters, such as poly(ethylene terephthalate), 25 poly(tetramethylene terephthalate), poly(cyclohexylene-1,4~imethylene terephthalate) or poly(oxymethylene-1,4-cyclohexylenemethyleneoxytere-phthaloyl), and the like; polyaryl sulfides, such as poly(l2-phenylene sulfide) or poly(thio-1,4phenylene), and the like; polyimides, such as poly-(pyromellitimido-l,~phenylene), and the like; polyolefins, such as polyethyl--` 2~ 232~:~
ene,~ polypropylene, poly(l-butene), poly(2-butene), poly(l-pentene), poly(2-pentene), poly(3-methyl-1-pentene), poly(4-methyl-1-pentene), 1,2-poly-1,3-butadiene, 1,4-poly-1,3-butadiene, polyisoprene, polychloroprene, polyacrylonitrile, poly(vinyl acetate), poly(vinylidene chloride~, polystyrene, 5 and the like; and copolymers of the foregoing, such as acrylonitrile-butadiene-styrene (ABS) copolymers, styrene-n-butylmethacrylate copolymers, ethylene-vinyl acetate copolymers, and the like.
Some of the more commonly used thermoplastic polymers include styrene-n-butyl methacrylate copolymers, polystyrene, styrene-n-butyl acrylate 10 copolymers, styrene-butadiene copolymers, polycarbonates, poly(methyl methacrylate), poly(vinylidene fluoride), polyarnides (nylon-12), polyethylene, polypropylene, ethylene-vinyl acetate copolymers, and epoxy resins.
Examples of thermosetting polymers include, again by way of - illustration only, alkyd resins, such as phthalic anhydride-g}ycerol resins, maleic acid -glycerol resins, adipic acid-glycerol resins, and phthalic anhydride-pentaerythritol resins; allylic resins, in which such monomers as diallyl phthalate, diallyl isophthalate diallyl maleate, and diallyl chlorendate serve as nonvolatile cross-linldng agents in polyester compounds; amino resins, such as aniline-formaldehyde resins, ethylene urea-formaldehyde resins, dicyandiamide-formaldehyderesins, melamine-formaldehyderesins, sulfonamide-formaldehyde resins, and urea-formaldehyde resins; epoxy resins, such as cross-linked epichlorohydrin-bisphend A resins; phenolic resins, such as phenol-formalde-hyde resins, including Novolacs and resols; and thermosetting polyesters, silicones, and urethanes.
In addition to the colorant, ultraviolet radiation transorber, molecular includant, and optional carrier, the colored composition of the present invention also can contain additional components, depending upon the application for which it is intended. For example, a composition which is to be utilized as a toner in an electrophotographic process also can contain, for 2123.~ ~
" .
example, charge carriers, stabilizers against thermal ox~dation, viscoelastic pro-perties modifiers, cross-linking agents, plasticizers, and the like. For some applications, the charge carrier will be the major component of the toner.
Charge carriers, of course, are well known to those having ordinary skill in 5 the art and typically are polymer-coated metal particles.
The amount or dosage level of ultraviolet radiation in general will be that amount which is necessary to mutate the colorant. The dosage level, in turn, typically is a function of the time of exposure and the intensity or flux of the radiation source which irradiates the colored composition. The latter is 10 effected by the distance of the composition from the source and, depending upon the wavelength range of the ultraviolet radiation, can be effected by the atmosphere between the radiation source and the composition. Accordingly, in some instances it may be appropriate to expose the composition to the radiation in a controlled atmosphere or in a vacuum, although in general 15 neither approach is desired.
The colored composition of the present invention can be utilized on or in any substrate. If the composition is present in a substrate, however, the substrate should be substantially transparent to the ultraviolet radiation whichis employed to mutate the colorant. That is, the ultraviolet radiation will not 20 significantly interact with or be absorbed by the substrate. As a practical matter, the composition typically will be placed on a substrate, with the most common substrate being paper. Other substrates, such as woven and nonwoven webs or fabrics, films, and the like, can be used, however.
When the colored composition is employed as a toner for an electro-25 photographic process, several variations are possible and come within thescope of the present invention. For example, the composition-based toner can be used to form a first image on a virgin paper sheet. The sheet then can be recycled by exposing the sheet to ultraviolet radiation in accordance with the present invention to render the colorant, and, as a consequence, the 'i ',.'~' ,~ ' - ~`''-' :. ~ ' ' "''- . i` ' ', ' ' ' ': ~ ~ ' , . .
-` 21232~
composition, colorless. A second image then can be formed on the sheet.
The second image can be forrned from a standard, known toner, or from a composition-based toner which is either the same as or different from the composition-based toner which was used to form the first image. If a 5 composition-based toner is used to form the second image, the sheet can be recycled again, with the number of cycles being limited by the build-up of now colorless composition on the surface of the paper. However, any subsequent image can be placed on either side of the sheet. That is, it is not required that a second image be formed on the side of the sheet on which the first image 10 was forrned.
In addition, the conversion of the composition-based toner image on the sheet to a colorless form does not have to take place on the sheet. For example, sheets having images formed from composition-based toners can be recyded in the traditional way. In place of the usual deinking step, however, 15 the sheets are exposed to ultraviolet radiation, either before or after beingconven~d to pulp. The colorless toner then simpl9 becomes incorporated into the paper formed from the resulting pulp.
The present invention is further described by the example which follows. Such example, however, is not to be construed as limiting in any 20 way either the spirit or scope of the present invention. In the example, all parts are parts by weight unless stated otherwise.
Example 1 This example describes the preparation of a B-cyclodextrin molecular includant having (1) an ultraviolet radiation transorber covalently bonded to the cyclodextrin outside of the cavity of the cyclodextrin and (2) a colorant associated with the cyclodextrin by means of hydrogen bonds and/or van der Waals forces.
-- 212328:~
A. ~ Friedel-Crafts Acylation of Transorber A 250-ml, three-necked, round-bottomed reaction flask was fitted with a condenser and a pressure-equalizing addition funnel equipped with a nitrogen inlet tube. A magnetic stirring bar was placed in the flask. While being flushed with nitrogen, the flask was charged with 10 g (0.05 mole~ of 1-hydroxycyclohexyl phenyl ketone (Irgacure~ 184, Ciba-Geigy Corporation, Hawthorne, New York), 100 ml of anhydrous tetrahydofuran (Aldrich Chemical Company, Inc., Milwaukee, Wisconsin), and 5 g (0.05 mole) of succinic anhydride (Aldrich). To the condnuously stirred contents of the flask then was added 6.7 g of anhydrous aluminum chloride (Aldrich). The resulting reaction mixture was maintained at about 0C in an ice bath for about one hour, after which the mixture was allowed to warm to ambient temperature for two hours. The reaction mixture then was poured into a mixture of 500 ml of ice water and 100 ml of diethyl ether. The ether layer was removed after the addition of a small amount of sodium chloride to the aqueous phase to aid phase separation. The ether layer was dried over anhydrous magnesium sulfate. The ether was removed under reduced pressure, leaving 12.7 g (87 percent) of a white crystalline powder. The material was shown to be 1-hydroxycyclohexyl ~(2-carboxyethyl)carbonylphenyl ketone by nuclear magnetic resonance analysis.
B. Preparation of Acylated Transorber Acid Chloride A 250-ml round-bottomed flask fitted with a condenser was charged with 12.0 g of l-hydroxycyclohexyl ~(2-carboxyethyl)carbonylphenyl ketone (0.04 mole), 5.95 g (0.05 mole) of thionyl chloride (Alddch), and 50 ml of diethyl ether. The resulting reaction mixture was stirred at 30C for 30 minutes, after which time the solvent was removed under reduced pressure.
The residue, a white solid, was maintained at 0.01 Torr for 30 minutes to remove residual solvent and excess thionyl chloride, leaving ~ 12.1 g - 19 - .' ,.
, 2123,~
(94 percent) of l-hydroxycyclohexyl 4-(2-chloroformylethyl)carbonylphenyl ketone.
C. Covalent Bondin~ of Acylated Transorber to Cyclodextrin A 250-ml, three-necked, round-bottomed reaction flask containing a 5 magnetic stirring bar and fitted with a thermometer, condenser, and pressure-equalizing addition funnel equipped with a nitrogen inlet tube was charged with 10 g (9.8 mmole) of B-cyclodextrin (American Maize-Products Company, Hammond, Indiana), 31.6 g (98 mmoles) of l-hydroxycyclohexyl 4-(2-chloroformylethyl)carbonylphenyl ketone, and 100 ml of N,N-dimethylform-10 amide while being continuously flushed with nitrogen. The reaction mixturewas heated to 50C and 0.5 ml of triethylamine added. The reaction mixture was maintained at 50C for an hour and allowed to cool to ambient tempera-ture. In this preparation, no attempt was made to isolate the product, a B-cyclodextrin to which an ultraviolet radiation transorber had been covalently 15 coupled (referred to hereinafter for convenience as B-cyclodextrin-transorber).
The foregoing procedure was repeated in order to isolate the product of the reaction. At the conclusion of the procedure as described, the reaction mixture was concentrated in a rotary evaporator to roughly 10 percent of the original volume. The residue was poured into ice water to which sodium 20 chloride then was added to force the product out of solution. The resulting precipitate was isolated by filtration and washed with diethyl ether. The solid was dried under reduced pressure to give 24.8 g of a white powder. In a third preparation, the residue remaining in the rotary evaporator was placed on top of an approximately 7.5-cm column containing about 15 g of silica gel. The 25 residue was eluted with N,N-dimethylformamide, with the eluant being monitored by means of Whatman~ Flexible-Backed TLC Plates (Catalog No.
05-713-161, Fisher Scientific, Pittsburgh, Pennsylvania). The eluted product was isolated by evaporating the solvent. The structure of the product was verified by nuclear magnetic resonance analysis.
~12328:1 D. ~ Association of Colorant with Cyçl~dçx~in-Transorber - Preparation of Colored Composition To a solution of 10 g (estimated to be about 3.6 mmole) of B-cyclodex-trin-transorber in 150 ml of N,N-dimethylformamide in a 250-ml round-5 bottomed flask was added at ambient temperature 1.2 g (3.6 mmole) ofMalachite Green oxalate (Aldrich Chemical Company, Inc., Milwaukee, Wisconsin), referred to hereinafter as Colorant A for convenience. The reaction mixture was stirred with a magnetic stirring bar for one hour at ambient temperature. Most of the solvent then was removed in a rotary 10 evaporator and the residue was eluted from a silica gel column as already described. The B-cyclodextrin-transorber Colorant A inclusion complex moved down the column first, cleanly separating from both free Colorant A and B-cyclodextnn-transorber. Eluant containing the complex was collected and solvent removed in a rotary evaporator. The residue was subjected to a 15 reduced pressure of 0.01 Torr to remove residual solvent to yield a blue-green powder.
E. Mutation of Col~e~ Composition The B-cyclodextrin-transorber Colorant A inclusion complex was exposed to ultraviolet radiation from two different lamps, Lamps A and B.
20 Lamp A was a 2æ-nanometer excimer lamp assembly organized in banks of four cylindrical lamps having a length of about 30 cm. The lamps were cooled by circulating water through a centrally located or inner tube of the lamp and, as a consequence, they operated at a relatively low temperature, i.e., about 50C. The power density at the lamp's outer surface typically is 25 in the range of from about 4 to about 20 joules per square meter ~J/m2).
However, such range in reality merely reflects the capabilities of current excimer lamp power supplies; in the future, hiBher power densities may be practical. The distance from the lamp to the sample being irradiated was 4.5 cm. Lamp B was a 50~watt Hanovia medium pressure mercury lamp .. , - ~- . . ~ . . .. : ~ .: - . . . .
2~ 2~281 (Hanovia Lamp Co., Newark, New Jersey). The distance from Lamp B to the sample being irradiated was about 15 cm.
A few drops of an N,N-dimethylformamide solution of the B-cyclodex-trin-transorber Colorant A inclusion complex were placed on a TLC plate and S in a small polyethylene weighing pan. Both samples were exposed to Lamp ~-A and were decolorized (mutated to a colorless state) in 15-20 seconds.
Similar results were obtained with Lamp B in 30 seconds.
A first control sample consisting of a solution of Colorant A and B-cyclodextrin in N,N-dimethylformamide was not decolorized by Lamp A. A
second control sample consisting of Colorant A and l-hydroxycyclohexyl phenyl ketone in N,N-dimethylforrnamide was decolorized by Lamp A within 60 seconds. On standing, however, the color began to reappear within an hour. ~-To evaluate the effect of solvent on decolorization, 50 mg of the B-cyclodextrin-transorber Colorant A inclusion complex was dissolved in 1 ml of solvent. The resulting solution or mixture was placed on a glass micro-scope slide and exposed to Lamp A for 1 minute. The rate of decolorization, i.e., the time to render the sample colorless, was directly proportional to the solubility of the complex in the solvent, as summarized below.
Solvent Solubilityl)ecolorization Time N,N-Dimethylformamide Poor 1 minute Dimethylsulfoxide Soluble ~10 seconds -Acetone Soluble <10 seconds Hexane Insoluble --Ethyl Acetate Poor 1 minute Finally, 10 mg of the B-cyclodextrin-transorber Colorant A inclusion complex were placed on a glass microscope slide and crushed with a pestle.
-` 212328::~
The-resulting powder was exposed to Lamp A for 10 seconds. The powder turned colorless. Similar results were obtained with lamp B, but at a slower rate.
S Example 2 Because of the possibility in ~he preparation of colored composition described in Example 1 for the acylated transorber acid chloride to at least partially occupy the cavity of the cyclodextrin, to the partial or complete exclusion of colorant, a modified preparative procedure was carried out.
Thus, this example describes the preparation of a B-cyclodextrin molecular includant having (1) a colorant at least partially included within the cavity ofthe cyclodextrin and associated therewith by means of hydrogen bonds and/or van der Waals forces and (2) an ultraviolet radiation transorber covalently bonded to the cyclodextrin outside of the cavity of the cyclodextrin.
A. Association of Colorant with a Cyclodextrin To a solution of 10.0 g (9.8 mmole) of B-cyclodextrin in 150 ml of N,N-dimethylforrnamide was added 3.24 g (9.6 mmoles) of Colorant A. The resulting solution was stirred at ambient temperature for one hour. The reaction solution was concentrated under reduced pressure in a rotary evaporator to a volume about one-tenth of the original volume. The residue wa~ passed over a silica gel column as described in Part C of Example 1. The solvent in the eluant was removed under reduced pressure in a rotary evaporator to give 12.4 g of a blue-green powder, B-cyclodextrin Colorant A
inclusion complex. ~ ~-B. Covalent Bondin~ of Acylated Transorber to Cyclodextrin Colorant Inclusion Complex - Prevaration of Colored Composition A 25~ml, three-necked, round-bottomed reaction flask containing a magnetic stirring bar and fitted with a therrnometer, condenser, and pressure-~ ~ 2 .~
equalizing addition funnel equipped with a nitrogen inlet tube was charged with 10 g (9.6 mmole) of B-cyclodextrin Colorant A inclusion complex, 31.6 g (98 mmoles) of l-hydroxycyclohexyl 4-(2-chloroformylethyl)carbonylphenyl ketone prepared as described in Part B of Example l, and 150 ml of N,N-S dimethylformamide while being continuously flushed with nitrogen. Thereaction mixture was heated to 50C and 0.5 ml of triethylamine added. The reaction mixture was maintained at 50C for an hour and allowed to cool to ambient temperature. The reaction mixture then was worked up as described in Part A, above, to give 14.2 g of B-cyclodextrin-transorber Colorant A
10 inclusion complex, a blue-green powder.
C. Mutation of Colored Composition The procedures describe in Part E of Example 1 were repeated with the B-cyclodextrin-transorber Colorant A inclusion complex prepared in part B, above, with essentially the same results.
Having thus described the invention, numerous changes and modifica-tionis hereof will be readily apparent to those having ordinary skill in the artwithout departing from the spirit or scope of the invention.
Claims (19)
1. A colored composition which comprises:
(A) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable;
(B) an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with said colorant to effect the irreversible mutation of the colorant; and (C) a molecular includant, with which each of said colorant and ultraviolet radiation transorber is associated.
(A) a colorant which, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable;
(B) an ultraviolet radiation transorber which is adapted to absorb ultraviolet radiation and interact with said colorant to effect the irreversible mutation of the colorant; and (C) a molecular includant, with which each of said colorant and ultraviolet radiation transorber is associated.
2. The colored composition of claim 1, in which said molecular includant has at least one reactive functional group and is adapted to form a molecular inclusion complex with at least one of said colorant and said ultraviolet radiation transorber.
3. The colored composition of claim 2, in which said molecular includant is selected from the group consisting of clathrates, zeolites, and cyclodextrins.
4. The colored composition of claim 3, in which said molecular includant is a clathrate.
5. The colored composition of claim 3, in which said molecular includant is a zeolite.
6. The colored composition of claim 3, in which said molecular includant is a cyclodextrin.
7. The colored composition of claim 2, in which said colorant is at least partially included within a cavity of said molecular includant
8. The colored composition of claim 7, in which said ultraviolet radiation transorber is associated with said molecular includant outside of saidcavity.
9. The colored composition of claim 8, in which said ultraviolet radiation transorber is covalently coupled to said molecular includant.
10. A method of irreversibly mutating a colored composition which comprises:
(A) providing a molecular includant, with which a colorant and an ultraviolet radiation transorber is associated; in which (1) said colorant, in the presence of said ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; and (2) said ultraviolet radiation transorber is adapted to absorb ultraviolet radiation and interact with said colorant to effect the irreversible mutation of the colorant;
and (B) irradiating said colored composition with ultraviolet radiation at a dosage level sufficient to irreversibly mutate said colorant.
(A) providing a molecular includant, with which a colorant and an ultraviolet radiation transorber is associated; in which (1) said colorant, in the presence of said ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; and (2) said ultraviolet radiation transorber is adapted to absorb ultraviolet radiation and interact with said colorant to effect the irreversible mutation of the colorant;
and (B) irradiating said colored composition with ultraviolet radiation at a dosage level sufficient to irreversibly mutate said colorant.
11. The method of claim 10, in which said molecular includant has at least one reactive functional group and is adapted to form a molecular inclusion complex with at least one of said colorant and said ultraviolet radiation transorber.
12. The method of claim 11, in which said colorant is at least partially included within a cavity of said molecular includant.
13. The method of claim 12, in which said ultraviolet radiation transorber is associated with said molecular includant outside of said cavity.
14. The method of claim 13, in which said ultraviolet radiation transorber is covalently coupled to said molecular includant.
15. The method of claim 11, in which said colored composition is applied to a substrate before being irradiated with ultraviolet radiation.
16. The method of claim 11, in which the mutated colorant is stable.
17. The method of claim 11, in which said ultraviolet radiation has a wavelength of from about 100 to about 375 nanometers.
18. The method of claim 17, in which said ultraviolet radiation is in-coherent, pulsed ultraviolet radiation from a dielectric barrier discharge ex-cimer lamp.
19. A method of preparing a colored composition which comprises:
(A) associating a colorant with a molecular incudant having at least one reactive functional group and which is adapted to form a molecular inclusion complex with said colorant; and (B) covalently bonding an ultraviolet radiation transorber to said molecular includant;
in which (1) said colorant, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; and (2) said ultraviolet radiation transorber is adapted to absorb ultravio-let radiation and interact with said colorant to effect an irreversible mutationof said colorant.
(A) associating a colorant with a molecular incudant having at least one reactive functional group and which is adapted to form a molecular inclusion complex with said colorant; and (B) covalently bonding an ultraviolet radiation transorber to said molecular includant;
in which (1) said colorant, in the presence of an ultraviolet radiation transorber, is adapted, upon exposure of the transorber to ultraviolet radiation, to be mutable; and (2) said ultraviolet radiation transorber is adapted to absorb ultravio-let radiation and interact with said colorant to effect an irreversible mutationof said colorant.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11991293A | 1993-09-10 | 1993-09-10 | |
| US119,912 | 1993-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2123281A1 true CA2123281A1 (en) | 1995-03-11 |
Family
ID=22387142
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2123281 Abandoned CA2123281A1 (en) | 1993-09-10 | 1994-05-10 | Colored composition mutable by ultraviolet radiation |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2123281A1 (en) |
-
1994
- 1994-05-10 CA CA 2123281 patent/CA2123281A1/en not_active Abandoned
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |