In recent years, as colored image-forming materials, materials particularly for forming color images are the main current. Concretely, are extensively utilized inkjet mode recording materials, thermal transfer mode recording materials, electrophotographic mode recording materials, transfer mode silver halide light-sensitive materials, printing inks, recording pens, and the like. Further, color filters are used for recording and reproducing color images in picture elements such as CCD in instruments for picture-taking, and in LCD and PDP in displays. In these color image-recording materials and color filters, in order to reproduce or record full-color images, dyes (dyestuffs and pigments) of three primary colors of the so-called additive color mixture process or subtractive color mixture process are used. However, it is the present status that dyes having an absorption characteristic capable of realizing preferred color reproduction areas and having a fastness so as to endure various use conditions and environmental conditions are not available, and improvements are being eagerly demanded.
The inkjet recording method becomes rapidly widespread and is being further developed because the material cost is cheap, high-speed recording is possible, a noise during the recording is low, and color recording is easy. The ink-jet recording method includes a continuous mode for continuously flying droplets and an on-demand mode for flying droplets according to image information signals. Further, the discharge mode includes a mode for applying a pressure by a piezoelectric element to discharge droplets, a mode for generating bubbles in an ink by heat to discharge droplets, a mode for using a ultrasonic wave, and a mode for aspirating and discharging droplets by electrostatic force. Moreover, as the inkjet ink, are used aqueous inks, oil based inks, or solid (melting type) inks.
The dyes used for such inkjet inks must meet the requirements that they are good in solubility or dispersibility in solvents; they can achieve high-speed recording; they have a good hue; they are fast to light, heat, and active gases (oxidizing gases such as NOx and ozone as well as Sox) in the environment; they have superior fastness to water or chemicals; they are good in fixing properties to image-receiving materials and hardly ooze; they are superior in preservability as inks; they have no toxicity; they have a high purity; and they are cheap.
In particular, the dyes are eagerly demanded such that they are a dye having a good cyan hue and having fastness to light, humidity and heat, especially they are fast to oxidizing gases in the environment, such as ozone, during printing on an image-receiving material having an ink-receiving layer containing porous white inorganic pigment particles.
In color copiers or color laser printers utilizing an electrophotographic mode, in general, toners having a coloring material dispersed in resin particles are widely used. As the performance required for the color toners, there are enumerated an absorption characteristic capable of realizing preferred color reproduction areas; a high light transmittance (transparency) that will be of a problem especially during the use by an overhead projector (hereinafter referred to as “OHP”); and various fastnesses under environmental conditions for use. The toners having a pigment as a coloring material dispersed in particles are disclosed in JP-A-62-157051, JP-A-62-255956, and JP-A-6-118715. Though these toners are superior in light fastness, they are insoluble so that they likely cause coagulation. Thus, they are problematic in a reduction of transparency of the colored layer and in a change of hue of the transmitted color. On the other hand, the toners using a dye as a coloring material are disclosed in JP-A-3-276161, JP-A-7-209912, and JP-A-8-123085. These toners are inversely high in transparency and free from a change of hue, but they are problematic in light fastness.
The thermal transfer recording has advantages such that the apparatus is small-sized and can realize a cost reduction; that its operation and maintenance are easy; and that a running cost is cheap. As the performance required for the dyes to be used in the thermal transfer recording, there are enumerated an absorption characteristic capable of realizing preferred color reproduction areas; coexistence of heat transfer properties and fixing properties after the transfer; heat stability; and various fastnesses of obtained images. However, none of the conventionally known dyes could meet all of these performances. For example, from an object to improve the fixing properties and the light fastness, a thermal transfer recording material and an image-forming method, in which a chelate is formed by a transition metal ion in an image-receiving material in which a heat diffusible dye is previously added are proposed in JP-A-60-2398, etc. However, the absorption characteristic of the formed chelate dye is in an unsatisfactory level, and there is a problem in environment by using the transition metal.
Since the color filters are required to have a high transparency, there was employed a method called a dyeing method for coloring using a dyestuff. For example, a method in which a dyeable photoresist is subjected to pattern exposure and development to form a pattern, which is then dyed with a dye of a filter color, is successively repeated with respect to all filter colors, whereby a color filter can be produced. Besides the dyeing method, color filters can also be produced by a method using a positive-working resist as described in U.S. Pat. No. 4,808,501, JP-A-6-35182, etc. According to these methods, since the dye is used, the transmittance is high, and the optical characteristics of the resulting color filters are superior. But, there are limits with respect to the light fastness, heat resistance, and the like. Accordingly, realization of dyes having superior various resistances and high transparency was demanded. On the other hand, there is widely known a method using an organic pigment having superior light fastness and heat resistance in place of the dye. But, it was difficult for color filters using a pigment to obtain the following optical characteristics.
The dyes to be used in the respective applications as described above must be commonly provided with the following properties. Namely, they have an absorption characteristic preferable for color reproducibility; they are good in fastnesses under the environmental conditions for use, for example, light fastness, heat resistance, resistance to oxidizing gases such as ozone, and fastness to other chemicals such as sulfurous gas; and they have a large molar absorption coefficient.
Hitherto, as the cyanine dye, phthalocyanine dyes having super hue and light fastness have been used in almost all cases. However, since the phthalocyanine dyes do not have a sufficient fastness to oxidizing gases, especially ozone, improvements are demanded.
As a dye skeleton used for inkjet ink, a phthalocyanine or triphenylmethane structure is representative. Incidentally, “Pc” as referred to this description means a phthalocyanine skeleton.
As representative phthalocyanine compounds that are most widely reported and utilized, are enumerated phthalocyanine derivatives classified into the following groups (1) to (6).    (1) Phthalocyanine copper compounds [for example, a mixture of Cu-Pc-(SO3Na)m, wherein m is from 1 to 4], such as Direct Blue 86 or Direct Blue 87.    (2) Direct Blue 199 and phthalocyanine compounds as described in, JP-A-62-190273, JP-A-63-28690, JP-A-63-306075, JP-A-63-306076, JP-A-2-131983, JP-A-3-122171, JP-A-3-200883, JP-A-7-138511, etc. [for example, a mixture of Cu-Pc-(SO3Na)m(SO2NH2)n, wherein (m+n) is from 1 to 4 (hereinafter, Pc means a phthalocyanine skeleton)].    (3) Phthalocyanine dyes as described in JP-A-63-210175, JP-A-63-37176, JP-A-63-304071, JP-A-5-171085, WO 00/08102, etc. [for example, Cu-Pc-(CO2H)m(CONR1R2)n, wherein (m+n) is a number of from 0 to 4].    (4) Phthalocyanine dyes as described in JP-A-59-30874, JP-A-1-126381, JP-A-1-190770, JP-A-6-16982, JP-A-7-82499, JP-A-8-34942, JP-A-8-60053, JP-A-8-113745, JP-A-8-310116, JP-A-10-140063, JP-A-10-298463, JP-A-11-29729, JP-A-11-320921, EP173476A2, EP468649A1, EP559309A2, EP596383A1, DE3411476, U.S. Pat. No. 6,086,955, WO 99/13009, GB2341868A, etc. [for example, Cu-Pc-(SO3H)m(SO2NR1R2)n, wherein (m+n) is a number of from 0 to 4, and m is not 0].    (5) Phthalocyanine dyes as described in JP-A-60-208365, JP-A-61-2772, JP-A-6-57653, JP-A-8-60052, JP-A-8-295819, JP-A-10-130517, JP-A-11-72614, JP-T-11-515047, JP-T-11-515048, EP196901A2, WO 95/29208, WO 98/49239, WO 98/49240, WO 99/50363, WO 99/67334, etc. [for example, Cu-Pc-(SO3H)l(SO2NH2)m(SO2NR1R2)n, wherein (l+m+n) is a number of from 0 to 4].    (6) Phthalocyanine dyes as described in JP-A-59-22967, JP-A-61-185576, JP-A-1-95093, JP-A-3-195783, EP649881A1, WO 00/08101, WO 00/08103, etc. [for example, Cu-Pc-(SO2NR1R2)n, wherein n is a number of from 0 to 4].
Now, the phthalocyanine dyes represented by Direct Blue 87 or Direct Blue 199, as widely used at present, are characterized in that they are superior in light fastness to generally known magenta dyes or yellow dyes.
However, the phthalocyanine dyes have a greenish hue under acidic conditions and are not suitable for cyan inks. For this reason, in the case where these dyes are used as an cyan ink, it is most suitable to use them under neutral to alkaline conditions. But, even when the ink is neutral or alkaline, in the case where a material to be recorded, which is used, is acidic paper, the hue of a printed matter may possibly be greatly changed.
In addition, the phthalocyanine dyes are discolored greenish and erased even by oxidizing gases that are often taken into account as an environmental problem nowadays, such as nitrogen oxide gas and ozone, and simultaneously, the printing density is lowered.
On the other hand, the triphenylmethane dyes and/or pigments are good in hue but are very inferior in light fastness, ozone gas resistance, etc.
After this, if the utilization field is enlarged, and the dyes are widely used in displays such as advertisements, the dyes will be more likely exposed to light and active gases in the environment. Accordingly, realization of dyes and ink compositions particularly having a good hue, an excellent light fastness and superior fastness to active gases (oxidizing gases such as NOx and ozone as well as Sox) in the environment are being eagerly demanded more and more.
However, the development of cyan dyes (for example, phthalocyanine dyes) and cyan inks, which can meet these requirements in a high level, is difficult, and it is the present status that dyes and inks meeting the requirements have not become available yet.
So far, the phthalocyanine dyes to which the ozone gas resistance is imparted are described in JP-A-3-103484, JP-A-4-39365, JP-A-2000-303009, etc. However, it is the present status that the hue and the fastness to light and oxidizing gases are not compatible with each other. Cyan ink products that are fully satisfactory with the requirements in the market have not been provided yet.