Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-05-19
2002-06-11
Schwartz, Pamela R. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S328000, C428S329000, C428S522000
Reexamination Certificate
active
06403198
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to recording media used for printers or plotters which utilize the ink jet recording system. Particularly, it relates to ink jet recording media having a gloss of photographic papers which is strongly demanded in the field of color recording and to recording media high in transparency and usable as OHP films.
With recent remarkable progress in ink jet printers or plotters, full-color and highly minute images can be easily obtained. Accordingly, development of ink jet recording media other than the conventional woodfree papers and coated papers is earnestly desired.
Ink jet recording system performs recording of images or letters by ejecting ink droplets according to various principles and absorbing them into recording media such as paper. Ink jet printers or plotters have the features that they are excellent in high-speed printability, produce little noise, are great in versatility of patterns to be recorded, and require no development-fixation step, and they are noticeable in that complicated images can be accurately and rapidly formed. Recently, the ink jet printers or plotters have rapidly spread in various uses, especially, as devices for making hard copies of image information such as letters and figures produced by computers. Furthermore, multicolor recording can be easily performed by using a plurality of ink nozzles. The multicolor ink jetting systems are not inferior in the resulting color images to the multicolor printing according to plate making systems or printing according to color photographic systems. Moreover, when a small number of prints are to be produced, they can produce the prints more cheaply than the printing techniques or photographic techniques.
Lately, cheap ink jet printers are commercially available which can output highly minute images equal to the images obtained by the silver salt photographic system. Ink jet recording media can give images of the same quality as those produced by silver salt photographic systems and, besides, they are very cheap. Therefore, the ink jet recording media provide economically a great merit for users who must change frequently the display images such as illumination signs or commercial samples which must have large areas. Moreover, recently, it becomes common to produce images on personal computers and correct the color arrangement or layout with observing the printout. Such is utterly impossible according to the conventional silver salt photographic systems while such operation can be readily performed by the ink jet recording, which is one of the merits of the ink jet recording systems.
The fields of utilization of ink jet printers or plotters which recently have especially been noticed are production of color block copies in the field of printing which requires image quality close to that of photographs, full-color image recording such as output of design images in the field of designing, and recording of image information produced by computers on transparent recording media by ink jet printers and utilizing the recorded information as films for OHP (overhead projectors) in presentation at a conference.
Owing to demands from the fields of utilization of ink jet printers or plotters and with spread of ink jet printers or plotters, demands for recording media are diversified, and, for example, there are demanded recording media having excellent appearance of high surface gloss equal to silver salt color photographs and recording media of high transparency usable as films for OHP.
As for the recording media used in the ink jet recording systems, efforts have been made from the side of apparatus or ink composition so that the general woodfree papers and coated papers for printing or writing can be used. However, with improvement in performances of ink jet recording apparatuses or expansion of uses, such as printing speed, minuteness of images, or full-color recording, ink jet recording media are also required to have the higher characteristics. These characteristics are as follows: inked dots have a high density and a light and clear color tone; ink is quickly absorbed into the recording media, and even when an inked dot overlaps another inked dot, the ink does not flow or blot; inked dots do not diffuse in lateral direction more than needed; and inked dots have smooth and distinct perimeter lines. Especially, in the case of color recording, not only the single color recording of yellow, magenta, cyan, and black, but also overlaying recording of these colors are carried out, and the amount of ink absorbed in the recording medium is further increased and, hence, very severe performances are required.
Ink jet recording media using alumina hydrates are proposed as those which are high in ink absorption speed and enhanced in transparency and glossiness. That is, ink jet recording media comprising a support on the surface of which an alumina hydrate is coated together with a water-soluble binder are disclosed, for example, in JP-A-60-232990, JP-A-60-245588, JP-B-3-24906, JP-A-2-276670, JP-A-3-215082, JP-A-4-37576, JP-A-4-67986, JP-A-5-16517, JP-A-5-24335, JP-A-5-32037, JP-A-5-50739, JP-A-5-286228, JP-A-5-301441, JP-A-6-48016, JP-A-6-55829, JP-A-6-183126, JP-A-6-184954, JP-A-6-199034, JP-A-6-199035, JP-A-6-218324, JP-A-6-255235, JP-A-6-262844, JP-A-6-270530, JP-A-6-286297, JP-A-6-297831, JP-A-6-297832, JP-A-6-316145, JP-A-7-68919, JP-A-7-68920, JP-A-7-76161, JP-A-7-76162, JP-A-7-82694, and JP-A-7-89221.
These ink jet recording media have an ink absorption layer comprising a porous alumina hydrate. The ink absorption layer comprising a porous alumina hydrate is composed of the alumina hydrate and a polyvinyl alcohol binder. However, the ink absorption layer comprising a porous alumina hydrate cracks at the time of drying due to the shrinkage of the alumina hydrate. Furthermore, a coating solution comprising an alumina hydrate and a polyvinyl alcohol binder is apt to increase in viscosity with time, and especially in the case of a coating solution which is high in solid concentration, the solution is inferior in handleability and the coating operation is difficult, and the operability in continuous coating is unsatisfactory.
For the inhibition of occurrence of cracks in the coat of the ink absorption layer comprising an alumina hydrate and a polyvinyl alcohol binder at the time of drying, JP-A-7-76161 proposes a method of inhibiting the cracking by improving strength of the coat by gelatinizing the polyvinyl alcohol binder with boric acid or a borate. However, the gelling reaction of polyvinyl alcohol and boric acid or a borate is very fast, and change in viscosity of the coating solution with time cannot be avoided and, hence, coating stability becomes inferior. Moreover, the gelling product causes streaking and, thus, results in deterioration of surface quality. JP-A-6-218324 proposes a method of coating the coating solution on a support and blowing ammonia gas to the coat before removal of solvent to gelatinize the coat. However, ammonia gas is not only highly corrosive, but also is explosive, and use of it is dangerous. Furthermore, excess ammonia gas must be recovered, and, thus, use of ammonia gas is not preferred from the points of operation and simplicity of equipment.
As a method for inhibiting increase of viscosity with time to improve stability of the coating solution with time, JP-A-4-67986 discloses a method of using a polyvinyl alcohol having a polymerization degree of 1000 or less as a binder and JP-A-4-309533 discloses a method of using a polyvinyl alcohol having a saponification degree of 50-90%.
According to these methods, the stability of the coating solution with time can be improved, but the improvement is still insufficient. Besides, even if the stability with time is excellent, cracks are apt to occur in the coat at the time of drying, and because of too low viscosity of the coating solution, film formability is inferior.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an ink jet recording medium having an ink absorp
Mitsubishi Paper Mills Limited
Schwartz Pamela R.
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