Stock material or miscellaneous articles – Ink jet stock for printing – Hardened – cured – or cross-linked ink receptive layer
Reexamination Certificate
2002-04-19
2004-08-17
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Hardened, cured, or cross-linked ink receptive layer
C428S032280, C428S032290, C428S032300, C428S032340, C428S032380, C427S407100, C427S411000, C427S385500, C427S391000
Reexamination Certificate
active
06777039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording material suited for inkjet recording using a liquid ink such as an aqueous ink, an oil ink, or a solid ink that has a solid state at room temperature and is used in a fused state in image printing, and particularly relates to an inkjet recording sheet excellent in ink receiving performance.
2. Description of the Related Art
In recent years, with the rapid progress of information industries, a variety of information processing systems have been developed, and recording methods and apparatuses suited for the information systems have also been developed and put to practical use.
Among the recording methods, an inkjet recording method has been widely spread, naturally, is naturally used in offices, and is used for so-called home use as well, because the method can be used on a variety of recording media, apparatuses therefor are comparatively low in cost, compact in size and excellent in quietness, and other advantages can be enjoyed.
Moreover, with the transition to high resolution image printing by inkjet printers in recent years, so-called photograph-like, high quality image recorded matter has also become available. Still moreover, with the progress in apparatus, various kinds of recording sheets for inkjet recording have also been developed.
Characteristics required of a recording sheet for use in the inkjet recording are generally listed as follows: (1) a quick drying property (high ink absorbing rate), (2) proper and uniform diameter of dots (no bleeding occurs), (3) good granularity, (4) high dot circularity, (5) high color density, (6) high chromaticity (with no dullness), (7) good lightfastness and water resistance of a printed portion, (8) high whiteness of the recording sheet, (9) good shelf stability of the recording sheet (no yellowing during long-term storage), (10) less deformability and good dimension stability (curling at a sufficiently low level), (11) being good in traveling through a machine, and the like. For application as a glossy photographic printing paper, which is used for acquiring so-called photograph-like high quality image recorded matter, requirements in addition to the above characteristics are glossiness, surface smoothness, a photographic printing paper-like touch analogous to silver halide photographs, and so on.
An inkjet recording sheet with a porous structure at a colorant-receiving layer has been developed into practical use for the purpose of improving the above characteristics. This inkjet recording sheet is excellent in ink absorptivity (quick drying property) and has high gloss because of the presence of the porous structure.
In Japanese Patent Application Laid-Open (JP-A) No. 11-115308, it is described that gas phase method (dry method) silica having a mean primary particle diameter of 10 nm or less is blended with polyvinyl alcohol (PVA) of a low saponification degree in an alkaline atmosphere with a pH value of 8 or higher and then dispersed to obtain a coating liquid, the coating liquid is applied on a substrate, and a coat film thus obtained is further coated in a still half-dry state with a coating liquid including a PVA hardener having a pH value of 8 or higher, followed by drying the composite coat film to form a colorant-receiving layer. According to this method, however, a print image is low in density and sharpness, and cannot acquire sufficient glossiness.
In JP-A No. 10-181190, it is described that an aggregate pigment is pulverized into fine powder in a cationic resin-containing liquid to form a coating liquid containing the pigment having a particle diameter of 500 nm or less, and the coating liquid thus obtained is applied on a substrate to form a colorant-receiving layer thereon, but printed images are low in density and sharpness with insufficient glossiness.
Moreover, in JP-A No. 2000-211235, description is given of an inkjet recording sheet containing vapor-phase-process silica and a cationic polymer having as a constituent unit a polydiallyl amine derivative, but printed images are low in density and sharpness with insufficient glossiness. Still moreover, in JP-A No. 2000-211241, description is given of an inkjet recording coating liquid that uses an aqueous dispersion containing vapor-phase-process silica and has a pH value of 1.0 to 4.5, but printed images are low in density and sharpness with insufficient glossiness and, in addition to this, cracking occurs on the surface of the recording sheet.
A method has been proposed in which vapor-phase-process silica is dispersed into cationic polymer, PVA and a hardener therefor are added into the dispersion to obtain a coating liquid, and the coating liquid thus obtained is applied on a substrate, followed by low temperature drying. However, the coating liquid easily coagulates; therefore, an image thereon is also insufficient in sharpness and glossiness.
Furthermore, a chance arises that the recording sheet curls at low temperatures, thereby causing poor traveling in a printer.
As described above, the current state is such that no inkjet recording sheet has been provided that has the following characteristics: on one hand, a colorant-receiving layer is stiff without producing cracking and so on, and on the other hand, not only can a high resolution image be formed with good ink absorptivity, but a formed print image also has ink retaining performance such as excellency of water resistance and resistance to bleeding over time, together with high image density and excellence in sharpness and glossiness.
SUMMARY OF THE INVENTION
The present invention solves the prior art problems and aims to achieve the following objects.
Firstly, it is an object of the present invention to provide an inkjet recording sheet excellent in density, sharpness and glossiness of a print image, low in curling, flat and excellent in printer transportability, without reducing other aspects of ink receiving performance.
Secondly, it is an object of the present invention to provide an inkjet recording sheet that is stiff, good in ink absorptivity, and capable of forming a high resolution print image without producing cracking.
Thirdly, it is an object of the present invention to provide an inkjet recording sheet very excellent in resistance to bleeding over time after printing, water resistance and ozone fading resistance, and showing high lightfastness even under irradiation with solar rays or fluorescent lights.
The above objects are achieved by the following means:
A first aspect of the present invention provides an inkjet recording sheet comprising a support and, on a surface of the support, a colorant-receiving layer formed by: applying a first coating liquid, which has a pH value of at most 5 and is obtained by adding a solution that includes polyvinyl alcohol, a high boiling point organic solvent and at least one of a first nonionic surfactant and an amphoteric surfactant, to a dispersion that includes vapor-phase-process silica having a specific surface area of at least 200 m
2
/g as measured by the BET method and a cationic resin, to form a coat layer; adding, to the coat layer formed by the application of the first coating liquid, a second coating liquid, which has a pH value of at least 8.5 or higher and includes a cross-linking agent capable of cross-linking the polyvinyl alcohol, an organic mordant and a second nonionic surfactant, either at the same time as the application of the first coating liquid or during drying of the coat layer of the first coating liquid but before the coat layer shows a decreasing rate of drying; and thereafter allowing the coated layer, to which the second coating liquid has been added, to harden and dry for forming a porous structure.
A second aspect of the present invention provides an inkjet recording sheet according to the first aspect, wherein the pH value of the first coating liquid is 3.7 or lower and the pH value of the second coating liquid is 9.2 or higher.
A third aspect of the present invention provides an inkjet recording sheet according to the firs
Kobayashi Takashi
Koike Kazuyuki
Nakano Ryoichi
Suzuki Katsuyoshi
Fuji Photo Film Co. , Ltd.
Kelly Cynthia H.
Shewareged B.
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