Note: Descriptions are shown in the official language in which they were submitted.
-- 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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- ~ 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
- ::
-6-
~ - 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-
~.
- 7 -
'
- 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 ~ -
-8-
--- 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
- 12-
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. ~ . ... ~ - . ,., -~ ,
. , . : - ~ - . ~ : -,, . : .
-: ~ . ~ ; . ~ . . . , -, .
,.. , .: . . ... ~ , :, : ,
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
- 13 -
''.,'. ,.. ',... ,,',.' ,',;'' ,: `~ , ;,, ' ' ~ ,. ,
-` 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
- 14-
...,, ., ... . ... - ~ . . ... ~.. . ..
:.. : .... - ... ., : ~ : ;. . . .
-` 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
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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
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, . .
-` 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
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,.
,
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.
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~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.
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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-
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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.
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