WO2008034003A2

WO2008034003A2 - Imaging compositions, imaging methods, and imaging members

Info

Publication number: WO2008034003A2
Application number: PCT/US2007/078403
Authority: WO
Inventors: Michael P. Filosa; Fariza Hasan; Zbigniew Jack Hinz
Original assignee: Zink Imaging, Llc
Priority date: 2006-09-14
Filing date: 2007-09-13
Publication date: 2008-03-20
Also published as: WO2008034003A3

Abstract

The present invention provides methods, imaging compositions and imaging members and, more particularly, to imaging methods, imaging compositions and imaging members for forming images that are resistant to ozone fading.

Description

IMAGING COMPOSITIONS, IMAGING METHODS, AND IMAGING MEMBERS

fOOOlJ This application claims priority from U.S. Provisional Application Serial No, 60/844,446, filed on September 14, 2006, incorporated herein by reference in its entirety.

HIlJlCin:HEJNVENTION

[§§02J The present invention relates generally to imaging methods, imaging compositions and imaging members and, more particularly, to imaging methods, imaging compositions and imaging members for forming images that are resistant to ozone fading.

BACKGROUND OF THE INVENTION

[O003J Copper phthaJocyanine (CuPC) dyes are extensively used in the formulation of printing inks and in the manufacture of thermal transfer coatings. Examples of the preparation and use of such dyes can be found, for example, in U.S. Patents 6,517,621 and 7,087,107, CuPC dyes can be tailored to have highly selective absorption of red light, and therefore make excellent cyan chromophobes for imaging systems that use three subtractive primary colors. These dyes possess additional advantages for printing and photographic applications, such as high solubility in various common solvents, high molar absorptivity, and superior light fastness. A significant drawback to the use of CuPC dyes, however, is their susceptibility to fading in the presence of ozone,

|§§§4] Ozone (O₃) is an extremely powerful oxidizing agent that is formed naturally from oxygen in the presence of light. Atmospheric ozone levels reach 0.2 ppm for at least one hour for 100 days of a typical year in Los Angeles, but are known to vary widely with location,

[0005] A great deal of attention has recently been paid to the problem of ozone-induced fading of colorants, In many ink jet printing applications there is no possibility to provide a barrier that would separate the image dye from the atmosphere. Furthermore, certain commonly- used ink-receiving coatings are microporous, and consequently have a high surface area. The rate of ozone-induced fading of CuPC dyes in such microporous environments can be extremely rapid,

|§006] Several types of materials, known as antiozonants, are known to scavenge ozone. For example, p-phenylenedi amines are used for reducing degradation of rubber (for example, in tires) due to ozone exposure. Many of these materials are not suitable for imaging applications, however, due to the formation of highly colored products formed in their reaction with ozone. Other methods used for minimizing degradation due to ozone exposure include providing a protective coating that is impermeable to ozone. However, as mentioned above, such coatings may not be easily applicable to images, except in a limited number of cases where polymeric over-laminates may be provided. Of course, any defect present in the protective layer might allow passage of ozone to a vulnerable CuPC dye,

J0007J Various attempts have been made to provide images which are more stable to ozone-induced fading. For example, U.S. Patent Application Publication No. 2003/0159616 describes ink jet compositions which include a rhodamine dye and a metallized magenta dye, U.S. Patent Application Publication No. 2006/0046934 describes imaging compositions that include a copper phthaiocyanine dye in combination with an aminoanthraquinone dye having reduced ozone-induced fading,

[0008] Nevertheless, to deal with this problem, there is ongoing in the art a continuing effort to find new imaging methods, compositions, and members which can form images which are resistant to ozone-induced fading.

SiMMARXOF TΗEJNVENTION

(Θ009J It is an object of this invention to provide novel imaging methods, imaging compositions, and imaging members that form images having improved ozone stability.

[OOIOJ Another object of this invention is to provide such imaging compositions that include a copper phthaiocyanine dye comprising a covalently-attached, unsaturated substituent for use in imaging methods and imaging members.

[0011] Another object is to provide thermal imaging methods and thermal imaging members that utilize the compositions of the invention.

[0012] A further object is to provide novel ink compositions for use in ink jet printing methods. f 0013 J In one aspect of the invention there are provided novel, color imaging compositions that include a copper phthaiocyanine dye comprising at least one alkenyl substituent. In accordance with the invention, the alkenyl substituent confers increased ozone stability without any deleterious change in color.

(0014] In another aspect of the invention there are provided novel color thermal imaging members and thermal imaging methods that utilize the imaging members, fOOlSJ The present invention provides for a compound having the structure:

.?_

in which at least one of substituents Ri - Rj₂ includes an alkenyl or alkynyl grouping.

[§016] The present invention also provides for a thermal imaging member including a substrate carrying a layer of a thermal image- forming material including the copper phthalocyanine compound of this invention.

[§§17] The present invention also provides for a thermal imaging process including heating the thermal imaging member of this invention, and image- wise transferring portions of the thermal image-forming material to a receiver member.

{00181 The present invention also provides for an ink composition including the compound of this invention dispersed or dissolved in a liquid carrier.

[0019J The present invention also provides for an ink jet printing process including transferring an ink composition including the compound of this invention,

MIEF DESCJiITC f0020] For a better understanding of the invention as well as other objects and further features thereof, reference is made to the following detailed description of various preferred embodiments thereof taken in conjunction with the accompanying drawings wherein; f 00211 FIG. 1 is a partially schematic, side sectional view of a color- forming imaging member according to the invention;

[0Q22J FIG. 2 illustrates the reflection spectra of control coatings and a coating composition of the present invention; and

[0023 J FIG. 3 illustrates the changes in reflection spectra of controls coatings and of a coating composition of the present invention after exposure to ozone. !12WITJONS

[0024J The term "alkyl" as used herein refers to saturated straight-chain, branched- chaln or cyclic hydrocarbon radicals. Examples of alkyl radicals include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, neopentyl, n-hexyl, cyclohexyl, n-octyl, n-decyl, n-dødecyl and n-hexadecyl radicals.

[0025J The term "alkenyl" as used herein refers to unsaturated straight-chain, branched- chain or cyclic hydrocarbon radicals. Examples of alkenyl radicals include, but are not limited to, allyl, butenyl, hexenyl and cyclohexenyl radicals.

[0026] The term "alkynyl" as used herein refers to unsaturated hydrocarbon radicals having at least one carbon-carbon triple bond. Representative alkynyl groups include, but are not limited to, ethynyl, 1-propynyl, 1 -butynyl, isopentynyl, 1 ,3-hexadiynyl, n-hexynyl, 3-pentynyl, l-hcxen-3-ynyl and the like.

[0027J The terms "halo" and "halogen," as used herein, refer to an atom selected from fluorine, chlorine, bromine and iodine.

[§028] The term "aryl," as used herein, refers to a mono-, bicyclic or tricyclic carbocyclic ring system having one, two or three aromatic rings including, but not limited to, phenyl, naphthyl, anthryl, azulyl, tetrahydronaphthyl, indanyl, indenyl and the like.

{0O29J The term "heteroaryl," as used herein, refers to a cyclic aromatic radical having from five to ten ring atoms of which: one ring atom is selected from S, O and N; zero, one or two ring atoms are additional heteroatoms independently selected from S. O and N; and the remaining ring atoms are carbon, the radical being joined to the rest of the molecule via any of the ring atoms, such as, for example, pyridinyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, isooxazolyl, thiadiazolyl, oxadiazolyl, thiophcnyl, furanyl, quinolinyl, isoquinolinyl, and the like. f§030] The term "heterocycloalkyl" as used herein, refers to a non-aromatic 3-, 4-, 5-, 6- or 7-membered ring or a bi- or tri-cyclic group comprising fused sϊx-menibered rings having between one and three heteroatoms independently selected from oxygen, sulfur and nitrogen, wherein: (i) each 5-membered ring has 0 to 1 double bonds and each 6-membered ring has 0 to 2 double bonds; (ii) the nitrogen and sulfur heteroatoms may optionally be oxidized; (iii) the nitrogen heteroatom may optionally be quatemized; and (iv) any of the above heterocyclic rings may be fused to a benzene ring. Representative heterocycles include, but are not limited to. pyrrolidinyl, pyrazolinyl, pyrazolidinyl, imidazolinyl, imidazolidinyl. piperidinyl, piperazinyl, oxazolidinyl, isoxazolidinyl, morpholinyl, thiazolidinyl, isothiazolidinyl, and tetrahydrofuryl. f^§031] The term "carbonyl" as used herein refers to a earbonyl group, attached to the parent molecular moiety through the carbon atom, this carbon atom also bearing a hydrogen atom, or in the case of a "substituted carbonyl" a substituent as described in the definition of "substituted" below,

{§0321 The term "aeyl" as used herein refers to groups containing a carbonyl moiety. Examples of acyl radicals include, but are not limited to, formyl, acetyl, propionyl, benzoyl and naphthyl.

[0033) The term "alkoxy", as used herein, refers to a substituted or unsubstitυted alkyl, alkenyl or heterocycloalkyl group, as previously defined, attached to the parent molecular moiety through an oxygen atom. Examples of alkoxy radicals include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, tert-butoxy, neopentoxy and n-hexoxy.

(G034J The term "aryloxy" as used herein refers to a substituted or unsubstituted aryl or heteroaryl group, as previously defined, attached to the parent molecular moiety through an oxygen atom. Examples of aryloxy include, but are not limited to, phenoxy, p-methylphenoxy, naphthoxy and the like,

JQ035J The term "alkylamino", as used herein, refers to a substituted or unsubstituted alkyl, alkenyl or heterocycloalkyl group, as previously defined, attached to the parent molecular moiety through a nitrogen atom. Examples of alkylamino radicals include, but are not limited to, methylamino, ethylamino, hexylaminoand dodecylamino,

[0036] The term "arylamino", as used herein, refers to a substituted or unsubstituted aryl or heteroaryl group, as previously defined, attached to the parent molecular moiety through a nitrogen atom.

[§037] The term "substituted" as used herein in phrases such as "substituted alkyl", "substituted alkenyl", "substituted aryl", "substituted heteroaryl", "substituted heterocycloalkyl", "substituted carbonyl", "substituted alkoxy", "substituted acyl", "substituted amino", "substituted aryloxy", and the like, refers to independent replacement of one or more of the hydrogen atoms on the substituted moiety with substituents independently selected from, but not limited to, alkyl, alkenyl, heterocycloalkyl, alkoxy, aryloxy, hydroxy, amino, alkylamino, arylamino, cyano, halo, mercapto, nitro, carbonyl, acyl, aryl and heteroaryl groups. DETAILED DESCRIPTION OF THE INVENTION

I

[0G38J Copper phthalocyanine dyes of the present invention may be represented by the formula I. The structure to which substituents Ri - Ri_ό are attached in formula I is hereinafter referred to as the "core structure" of the copper phthalocyanine (CuPC) dye. The CuPC dyes that are useful according to the invention are those in which at least one of the substituents Ri - Ri₆ comprises a grouping that reacts with and scavenges ozone.

[0039 J It is well known in the art that unsaturated groups such as alkenes or alkynes react readily with ozone to produce a five-membered ozonide ring, following which hydrolysis yields carbonyl products. Other readily oxidized groupings, such as amines or phenols (especially hydroquinones) are known to react rapidly with ozone.

[0040J One convenient manner in which such groupings may be attached to the CuPC core structure is through a sulfonamide linkage. Sulfonated CuPC dyes are readily available commercially, particularly the non-regiospecific tetrasulfonate. This material is readily converted to the tetrasulfonyl chloride using a chlorinating agent such as phosphorus oxychloride or thionyl chloride, following which displacement of chlorine with an amine yields a sulfonamide. If the amine bears an ozone-scavenging substituent, this grouping becomes attached to the CuPC core structure.

[0041] Although the linkage of the ozone-scavenging grouping has been described as occurring through a sulfonamide linkage, it will be clear to one of ordinary skill in the art that many other covalent linking mechanisms might be used. For example, linkage can occur through a carbonyl group as an ester or an amide, through a heteroatom as an ether, sulfide, or amine, through a carbon atom or chain of carbon atoms, etc.

[0042] Noncovalent linkage is also possible, for example, if one of the substituents Ri - Ri6 bears a charge and the ozone scavenger either bears the opposite charge or is attached to a moiety that bears the opposite charge.

[00431 The linkage of the scavenging group to the core structure of the dye ensures that the scavenger and the chromophore requiring protection are always in close association. Without such a linkage, it is possible that the scavenger and the chromophore might become separated through diffusion. f 0044 J Preferred copper phthalocyanine dyes of the present invention include those in which at least one of substituents R) - Rj₆ comprises a sulfonamido substituent, in which the sulfur atom is directly attached to the core structure, and in which the nitrogen atom of the sulfonamido substituent comprises at least one alkenyl or alkynyl substituent.

[QQ45J Especially preferred copper phthalocyanine dyes include those in which at least one of Ri - R₄, at least one of R₅ - Rg, at least one of Rg - Rn, and at least one of Ro - Ri₆ comprise a sulfonamido substituent, in which the sulfur atom is directly attached to the core structure, and in which the nitrogen atom of the sulfonamido substituent comprises at least one alkenyl or alkynyl substituent. fβ§46J Referring now to FIG. 1 there is illustrated a color-forming thermal imaging member according to the invention. Imaging member 10 includes a substrate 12 carrying color image-forming material layer 14 and is preferred for use in thermal transfer printing methods, such as thermal wax transfer printing and dye-diffusion thermal transfer printing, which typically involve the use of separate donor and receiver materials.

[0047J Substrate 12 may be of any suitable material for use in thermal imaging members, such as polymeric materials, and may be transparent or reflective, and also microporous.

[0048] Image-forming material layer 14 may include one or more copper phthalocyanine dyes of formula I. Copper phthalocyanine dyes are typically cyan and absorb in the red region of the spectrum (i.e., between about 550 and about 750 nm), although some are infrared dyes and absorb at wavelengths greater than 750 nm.

[0049] Image- forming layer 14 may be of any thickness. The thickness of the layer in any particular instance is primarily dependent upon the particular application. For example, layer 14 can be from about 0.5 microns to about 4.0 microns in thickness, preferably about 2 microns. Image- forming layer 14 may include dispersions of solid materials, encapsulated liquid, amorphous or solid materials, solutions of active materials in polymeric binders, or any combinations of the above,

[O05ΘJ Particularly preferred thermal transfer imaging members according to the invention are those of the type described in U.S. Pat. No. 6,537,410 B2. Such thermal imaging members, or donor elements, include a substrate bearing a layer of thermal transfer material including a dye-containing, amorphous (non-crystalline) phase that includes at least one dye and wherein the dye or dyes present in the amorphous phase form a continuous film. Optionally, and preferably, the thermal transfer material layer includes at least one thermal solvent such that at least part of the thermal solvent material is incorporated into the dye-containing phase and another part of the thermal solvent forms a second, crystalline phase separate from the dye- containing phase. The crystalline thermal solvent in the thermal transfer material layer melts and dissolves or liquefies the dye-containing phase thereby permitting dissolution or liquefaction to occur at a temperature lower than that at which such dissolution or liquefaction occurs in the absence of the crystalline thermal solvent. The thermal transfer material layer is characterized in that it is a solid transparent or translucent film, which does not undergo any detectable flow at room temperature and the film is fotτned by the dye(s) in the amorphous phase.

[0051] The dyes which are used in the thermal transfer material layers of such thermal transfer imaging members can be those that form solids which are themselves amorphous. That is to say, these dyes can be solids that lack the long-range ordered structure characteristic of crystalline solids. Amorphous solids formed from low molecular weight organic compounds have been described in the art. Such films can be stabilized with respect to the corresponding crystalline phase either thermodynamically (for example, by using in the glass phase a mixture of two or more chemically similar molecules) or kinetically, by means of a network of weak bonds (for example, hydrogen bonds) between the individual molecules.

{§052] In the two-phase embodiment, the thermal transfer material layer comprises a mixture of the dye-containing phase and at least one "thermal solvent," which is a crystalline material. At least a portion of the thermal solvent present in the thermal transfer material layer forms a phase separate from the dye-containing phase. The thermal solvent is believed to be equilibrated between the amorphous form present in the dye-containing amorphous phase and the crystalline form present in the other phase.

(§053 J The amount of thermal solvent that can be present in the dye-containing amorphous phase is thought to be limited by the melting temperature, Tg, of the amorphous phase which is preferably at least about 5O⁰C and particularly preferably about 6O⁰C, In this manner blocking, i.e., sticking together, of the thermal transfer donor sheets can be avoided even under high temperature storage conditions. Preferably, there should be no first order phase change for the entire thermal transfer material layer, i.e., there should be no melting of the layer, below about 5O⁰C,

[Θ054J The crystalline thermal solvent melts during the heating of the donor sheet and dissolves or liquefies the dye-containing phase, thereby permitting the transfer of portions of the transfer layer to the receiving sheet to occur at a temperature lower than such transfer would occur in the absence of the crystalline thermal solvent. The mixture of dye(s) and thermal solvent melts at a temperature, which is approximately the same as that of the crystalline thermal solvent itself (and substantially below the melting point of the dye in the powder (crystalline) form).

(0055] In some preferred embodiments, the thermal solvent selected for the transfer layer is a good solvent for the dye(s) of the dye-containing phase. In these embodiments, the dot size of the transferred imaging material may be varied by use of a thermal printing head optimized for variable dot printing. The two phase embodiment allows dye transfer to be effected at temperatures substantially lower than those achievable when the transfer layer contains only the same dye-containing phase, and hence with lower energy inputs per unit area imaged. The thermal solvent used can be any fusible material which melts above ambient temperature and which dissolves or liquefies the dye-containing phase to form a mixture which transfers at a lower temperature than that of the dye-containing phase alone.

[0056] The ratio of thermal solvent to dye may range from about 1 :3 by weight to about 3:1. A preferred ratio is about 2:1. Thus, the two phase embodiment can provide a major reduction of imaging temperature, while maintaining a thin donor layer. The thermal solvent may separate into a second phase as the mixture cools after imaging, and preferably the thermal solvent should not form such large crystals that it adversely affects the quality of the resulting image. The thermal solvent preferably has a melting point sufficiently above room temperature such that the donor layer is not tacky at room temperature, and does not melt at temperatures likely to be encountered during transportation and storage of the donor sheet prior to imaging,

[0057J The crystalline thermal solvents used in the two-phase embodiments typically have a melting point in the range of from about 6O⁰C to about 12O⁰C and preferably in the range of from about 85⁰C to about 100⁰C. It is particularly preferred that the thermal solvent have a melting point of about 9O⁰C. [0058] When the Imaging compositions of the invention are used in a image-forming layer of a thermal imaging member of the type described in U.S. Pat. No. 6,537,410 B2, the image- forming layer is as thin as possible consistent with good imaging characteristics, especially the maximum optical density of the image which typically should be at least about 1.5. Therefore, in this type of a thermal imaging member the image-forming layer typically has a thickness not greater than about 1 ,5 microns and preferably not greater than about 1 1.0 microns. For applications in which the thermal image- forming members of the invention are used in a thermal transfer imaging method, any suitable image-receiving member may be used. Typical image-receiving members are described in U.S. Pat. No. 6,761,788 Bl ,

[0QS9| When used in thermal transfer imaging methods, the thermal image-forming members of the invention may include a substrate carrying a layer of a copper phthalocyanine dye of the present invention. The thermal image- forming members of the invention, as illustrated in FIG. 1, may be used individually in a thermal monochrome imaging method or used in multicolor thermal imaging methods in conjunction with one or more different thermal image- forming members of different colors such as magenta and yellow image- forming members. Alternatively, the thermal image- forming members of the invention may include sections, or "patches" of two or more differently disposed adjacent to each other on the same substrate.

[0060] Such thermal imaging members and various combinations thereof are generally well known, and various methods of preparing heat- sensitive recording elements employing these materials also are well known and have been described, for example, in U.S. Patent Nos. 3,539,375; 4,401,717; 4,415,633; and 4,503,095. The color thermal imaging compositions of the invention may be used in any suitable thermal imaging members and thermal imaging methods. Many thermal imaging methods, both of the transfer type and the direct type, are known in the art and therefore extensive discussion of such methods is not required. Generally, in thermal transfer imaging methods the thermal imaging member is brought into contact with an image-receiving member and an imagcwise pattern of image material is transferred to the image- receiving member in accordance with an imagewise pattern of thermal energy applied to the thermal imaging member by a thermal print head or print heads.

(§061] The formulation of ink jet ink compositions of the invention, and the printing apparatus and methods used to carry out ink jet printing, can be effected using techniques which are well known in the art. Thus, the copper phthalocyanine dyes of the present invention can be formulated into aqueous ink compositions using conventional techniques, which are well known to those skilled in the preparation of such ink compositions. For example, the ink composition

40- may contain an alcohol or a glycol as a co-solvent. Some of the substituents R₁ - Ri₆ may be chosen such that the copper phthalocyanine dye is soluble in water. Thus, for example, at least one of substituents Ri - Rj₆ may comprise a sulfonate grouping. In this case, the phthalocyanine dye of the present invention will bear a net negative charge, and a counterion of positive charge will also be present. Such a counterion may for example be a metal ion, for example, Na^"", or an ammonium ion. The ink compositions may contain any suitable additives. Typical additives for such compositions include stabilizers, viscosity modifiers, bactericides, fungicides, etc. Typically, a measured quantity of each ink composition is placed in a separate ink jet cartridge comprising a housing having walls defining a reservoir for the ink and an outlet through which the ink leaves the cartridge and flows to a print head (typically of the thermal or piezoelectric type) which provides a stream of droplets of the ink and directs these droplets to a receiver surface, which typically is a paper sheet.

EXAMPLES

[0062] The method of the invention will now be described further with respect to specific preferred embodiments by way of examples, it being understood that these are intended to be illustrative only and the invention is not limited to the materials, amounts, procedures and process parameters, etc. recited therein.

[§§63 J Example I - Preparation of a copper phthalocyanine dye of the present invention.

[0064J This Example illustrates the preparation of a dye of Formula I in which R i , Rv R₄, Rs. one of R₆ and R₇, Rg, RQ, one of Rio and Rn, R_]2, Rp, one of R_i4 and R_)S and Rj₆ are each hydrogen, and Ra and the other of R₆ and R₇, the other of Rio and Rn, and the other of R₁₄ and Ri₅ are each an N,N-diallylaminosulfonyl substituent. This material is hereinafter referred to as Dye A.

[§§65] Copper(II) phthalocyaninetetrasulfonic acid, tetrasodium salt (5 g, 5 mmol, with non-regiospecific sulfonation, available from Aldrich Chemical Company, Milwaukee, WI) was suspended in sulfoJane (20 mL) and dimethylacetamide (5 mL). Phosphorus oxychloride (24.52 g, 160 mmol) was added and the reaction mixture was heated at reflux for 4 hours. The reaction mixture was then cooled to room temperature and poured into ice water with rapid stirring. The blue solid that precipitated was collected, washed with water, and dried in a vacuum desiccator at room temperature for 24 hours.

[0066] The crude tetrasulfonylchloride (1O g, 1 1 mmol) was then mixed with methylene chloride (200 mL) and the solution/suspension that resulted was cooled to 4⁰C. A large excess of diallylamine (10.7 g, 110 mmol) was slowly added to the cooled solution and then the mixture was allowed to warm to room temperature and stirred for 16 hours. The crude reaction mixture was placed onto a 1 kg plug of dry silica gel and eluted with dichloromethane (4 L). A greenish colored material came off and was discarded. The silica, to which the product was adsorbed, was then dried by air suction. The elution was then continued with 1 : 1 ethyl acetate/hexanes (8 L), which removed a dark brown impurity. The elution mixture was then changed to 4; 1 ethyl acetate/ hexanes (8 L). The fraction so eluted contained the desired phthalocyanine dye.

[§067] The solvent was removed on a rotary evaporator to give 3 g (23% yield) of the purified Dye A, molecular weight (Mw) = 1212; absorbance maximum (in dichloromethane solution) = 676 nm, ε = 123,000 L mol^"1 cm⁴. Dye A contains eight ally! (i.e., alkenyl) groupings.

[0068] Using the above procedure, two dyes of similar structure to Dye A but lacking the alkenyl groupings were prepared. Dye B was prepared using diethoxyethylamine instead of diallylamine, and thus contained eight ethoxymethylene groupings. Dye C was prepared using dibutyl amine instead of diallylamine and thus contained eight butyl groupings.

[0069] Example II - preparation of a thermal transfer coating comprising Dyes A, B and C and a commercially available control dye. Printing of an image by thermal transfer, and assessment of the stability of the image to fading in the presence of ozone,

[§§70] Coatings of imaging compositions comprising a Dye A (of the present invention), Dyes B and C (similar in structure to Dye A of the present invention, but lacking an alkenyl substituent), and a commercially available copper phthalocyanine dye (e.g., Solvent Blue 70) were formed as follows.

{§§71J Coating compositions were prepared by dissolving the dyes (4.29% by weight) in n-butanol (85% by weight), together with a thermal solvent (10.71% by weight N-Dodecyl-4- methoxybenzamide, prepared as described in aforementioned U.S. Patent No. 6,537,410 B2). The resultant solutions were coated onto a polyethylene terephthalate film base of approximately 4.5 micron thickness which had a slip coating for thermal printing on the opposite side, and dried using warm air. The coverage of the dried coatings was 1 g/m².

[§§72] The resulting donor elements were placed over a receiver sheet of the type described in U.S. Pat. No. 6,761,788 B2, with the coated side of the donor element in contact with the microporous receiver coating. The resulting assembly was printed using a laboratory test-bed printer equipped with a thermal head supplied by Kyocera Corporation, Kyoto, Japan, as described below. The following printing parameters were used: [0073 ] Print head width : 4 inches

[0074] Resistor size: 70 X 70 microns

[0075] Resistance: 1124 Ohm

[0076] Voltage: 1 1 V

(0G77J Print speed: 1 ,67 inches/second (2 msec per line)

[0078] Pressure: 1.5-2 Ib/linear inch f§079] Donor peeling: 90 degree angle, 0.1-0.2 seconds after printing

J0O8OJ Dot pattern: Odd-numbered and even-numbered pixels printed alternately in successive lines; one pixel (70 micron) spacing between lines in paper transport direction.

{§081 J The images formed with the control and the imaging member of the invention were exposed to ozone and densities before and after exposure were read as follows.

{0082 J Regions of maximum density of the transferred images were exposed in an ozone chamber constructed from a PYREX jar (1.2 ft ) and a mercury-argon lamp. Ozone was produced in situ by the direct photolysis of oxygen in the ambient air within the chamber. A fan within the chamber ensured that all samples were uniformly exposed. The temperature in the ozone chamber was between 21-23⁰C and relative humidity was 47-50%. The images were exposed to ozone for fixed periods of time. For each set of experiments, a "control" image, which was an image obtained using thermally-transferred Solvent Blue 70 with cyan reflection density of very close to 1.0, was exposed with the lest samples. A comparison of the extent of change of each of the control, Solvent Blue 70 images was used as a method to calibrate the effective ozone concentration in the chamber for each experiment. Changes of the Solvent Blue 70 images were practically identical from run to run, indicating the concentration of ozone in the chamber during these experiments remained substantially unchanged. Since the aim of these experiments was to compare the ozone resistance of the copper phthalocyanine dyes under identical conditions, it was not necessary to measure the exact concentration of ozone in the chamber.

|§083 J The ozone stability of each of these dyes was compared by overall spectral changes and quantified by the extent of the initial reflection densities (cyan, magenta and yellow) of the images before and after ozone exposure. A GRETAG SPM 500 densitometer was used for these measurements. The conditions for the measurements were: illumination = D50, observer angle = 2°, density standard = ANSI A, reflection standard = white base, and no filter. [0084] The results are shown In Table L

TABLE 1

(§085] It can be seen that the percentage of retained Dye A (of the present invention) in cyan density (94%) is much higher than that of the control dyes (38%, 68%, 70%). Moreover, the increase in yellow density is less marked for Dye A of the present invention than for the control materials.

[0086] The reflection spectra of regions of maximum density of the printed images made from the thermal transfer compositions containing Solvent Blue 70 (control, curve 20), Dye A of the present invention (curve 22), and Dyes B and C (controls, curves 24 and 26, respectively), are shown in FIG. 2. A comparison of the spectra of the dyes shown in FIG. 2 shows the presence of more H-aggregation, as indicated by a blue shift, in Dye A (curve 22) than in the other dyes. The spectra of the dyes dissolved in dichloromethane show no such aggregation, and are very similar for each of Dyes A, B and C. It is possible that aggregation contributes to the observed improvement in ozone stability, but this is merely a hypothesis that is not intended to limit the present invention in any way.

[0087J Figure 3 shows the spectral changes induced by exposure to ozone of regions of maximum density of the printed images made from the thermal transfer compositions containing Solvent Blue 70 (control, curve 30), Dye A of the present invention (curve 32), and Dyes B and C (controls, curves 34 and 36, respectively). None of the three compositions comprising Solvent Blue 70, Dye C, or Dye D, each of which lacks an alkenyl substϊtuent, is seen to be as stable as the coating composition comprising Dye A of the present invention in the presence of ozone. Indeed, almost no change is observed in the composition comprising Dye A under the conditions of the experiment. It is possible that the unsaturated substituents present in Dye A react with, and scavenge, ozone.

J0O88J Although the Invention has been described in detail with respect to various preferred embodiments, it is not Intended to be limited thereto, but rather those skilled in the art will recognize that variations and modifications are possible which are within the spirit of the invention and the scope of the appended claims.

IQUJYALENTS

1§O89J The present invention is not to be limited in terras of the particular embodiments described in this application, which are Intended as single illustrations of individual aspects of the invention. Many modifications and variations of this invention can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the invention, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present Invention is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled.

45-

Claims

We claim:

1. A copper phthalocyanine compound of structure I

1 in which at least one of substituents Ri - Rn comprises an alkenyl or aJkynyl grouping,

2. The copper phthalocyanine compound of Claim 1, In which substituents Ri - R 1₂ comprise at least four alkenyl or alkynyl groupings.

3. The copper phthalocyanine compound of Claim 1, in which substituents Rj - Ri₂ comprise at least eight alkenyl or alkynyl groupings,

4. The copper phthalocyanine compound of Claim 1, in which an alkenyl or alkynyl grouping is covalently attached to the core structure through a sulfonamide grouping.

5. The copper phthalocyanine compound of Claim 1 , in which a charged moiety comprising an alkenyl or alkynyl grouping Is associated with a grouping bearing the opposite charge attached to the core structure.

6. The copper phthalocyanine compound of Claim 1, in which at least one of Ri - R4, at least one of R₅ - Rg, at least one of R9 - Rn, and at least one of R₁3 - Rj₆ comprise a sulfonamide substituent, in which a sulfur atom of the sulfonamido substituent is directly attached to a core structure of the compound, and in which a nitrogen atom of the sulfonamido substituent Is attached to at least one alkenyl or alkynyl substituent.

7. A thermal Imaging member comprising a substrate carrying a layer of a thermal image-forming material comprising a copper phthalocyanine compound as defined In claim 1.

8. The thermal Imaging member of claim 7, wherein said layer of thermal image- forming material comprises a dye-containing amorphous phase comprising said copper phthalocyanine compound, wherein said dye-containing amorphous phase forms a continuous film.

9. The thermal imaging member of claim 7, wherein said layer of thermal image- forming material further includes a thermal solvent, at least a portion of said thermal solvent adapted to form a separate crystalline phase.

10. The thermal imaging member of claim 9, wherein said thermal solvent has a melting point above 5O⁰C,

1 1. The thermal imaging member of claim 10, wherein said layer of image-forming material has a thickness not greater than 1 micrometer,

12. A thermal imaging method comprising heating a thermal imaging member as defined in claim 7, and imagewise transferring portions of the theniial image-forming material to a receiver member.

13. The thermal imaging method of claim 12, wherein said layer of thermal image- forming material comprises a dye-containing amorphous phase comprising said copper phthalocyanine compound.

14. The thermal imaging method of claim 13, wherein said layer of thermal image- forming material further includes a thermal solvent, at least a portion of said thermal solvent forming a separate crystalline phase.

15. The thermal imaging method of claim 14, wherein said thermal solvent has a melting point above 5O⁰C.

16. The thermal imaging method of claim 12, wherein said layer of image-forming material has a thickness not greater than about 1 micrometer.

17. An ink composition comprising a compound as defined in claim 1 dispersed or dissolved in a liquid carrier.

18. The ink composition of claim 17, wherein said liquid carrier is selected from the group consisting of: water; aqueous alcohol; and aqueous glycol.

19. An ink jet printing method comprising transferring an ink composition as defined in claim 17, to a receiver member.

20. The ink jet printing method of claim 19, wherein the ink composition comprises cyan ink, said method further comprising transferring said cyan ink, yellow ink, and magenta ink to a receiving member, said transfer resulting in the production of a full-color image.