Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2002-03-20
2004-03-23
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C347S101000, C428S195100
Reexamination Certificate
active
06709097
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
The entire disclosures of Japanese Patent Application No. 2001-080955 filed on Mar. 21, 2001 and Japanese Patent Application No. 2001-177192 filed on Jun. 12, 2001 including specifications, claims and summaries are incorporated herein by reference in their entireties.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording medium, particularly to a recording medium suitable for an ink a jet printer.
2. Discussion of the Background
An ink jet recording system is a system wherein ink droplets are jetted at a high velocity from a nozzle to form an image directly on a recording medium. A printer employing such an ink jet system has found remarkable widespread use in recent years, since it can easily be small-sized, it is easy for full coloring or high speed modification, or its printing noise is low.
As a recording medium for an ink jet printer, one having a porous ink receiving layer comprising fine inorganic particles such as silica or alumina and a binder such as polyvinyl alcohol, formed on a substrate such as a paper or a film in order to quickly absorb ink and to obtain a clear image, has been known. The recording medium for an ink jet printer is required to absorb the solvent contained in a large quantity in the ink by pores in the ink receiving layer, and accordingly, the ink receiving layer is required to have pores with a large pore radius and a large pore volume. Further, as the ink receiving layer is more transparent, a clearer image having a high color density can be formed, and accordingly, the ink receiving layer is preferably one having good transparency.
Further, in addition to the above-mentioned ink absorptivity and transparency, it has become important that, as an aqueous ink is used in an ink jet recording system, even when a recorded product is in contact with water, no running of ink should take place as a result of flowing of a dye in the ink (hereinafter referred to as water resistance), or even if the surface of the recording medium is in contact with a hard object, it should be free from receiving scratches and thus free from impairment of the quality of the recorded product (hereinafter referred to as scratch resistance), or the surface gloss is high (hereinafter referred to as glossiness).
In order to cope with these requirements, many ink jet recording media have heretofore been proposed. JP-A-2000-21892 discloses a recording sheet having a high color density and gloss, which comprises a substrate, a porous layer containing boehmite, formed on the substrate, and a porous layer having composite particles comprising silica and alumina bound by a binder, formed on the porous layer containing boehmite. The process for producing such a recording sheet is a process wherein a coating fluid composed of a composite sol comprising silica and alumina, is coated and then dried as pressed against a die having a smooth surface. Accordingly, such a process is applicable to a case where a paper is used as the substrate as in Examples given in the publication, but it can not be applied in the case of a water-impermeable substrate such as a resin film or a resin coated paper having a polyolefin resin coating layer (so-called RC paper), since the solvent in the coating fluid can not be thereby evaporated and removed at the time of drying.
Further, JP-A-2000-351267 discloses a recording medium for pigment ink, which comprises a substrate, an ink receiving layer containing boehmite, formed on the substrate, and a layer formed from a coating fluid containing oxide particles such as alumina ultra fine particles or silica particles treated with aluminum polychloride, having an average particle size of from 10 to 200 nm, and having a pH of from 3 to 11, laminated on the ink receiving layer.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide an ink jet recording medium which has ink absorptivity suitable for ink jet recording and which is suitable for recording in high color density and further is excellent in water resistance, scratch resistance and glossiness.
The present invention provides an ink jet recording medium comprising a substrate, an ink receiving layer containing fine inorganic particles, formed on the substrate and a layer containing silica/alumina composite particles, formed on the ink receiving layer, wherein the layer containing silica/alumina composite particles, is a layer containing a xerogel having an average pore radius of at least 6.0 nm, obtained by removing a solvent from a silica/alumina composite sol containing agglomerated particles comprising silica and alumina.
The layer containing silica/alumina composite particles, is a layer obtained by removing a solvent from a silica/alumina composite sol containing agglomerated particles comprising silica and alumina as colloidal particles. The silica or alumina may be hydrate of silicon oxide or hydrate of aluminum oxide respectively. The coating fluid obtained by mixing the silica/alumina composite sol, a binder and a solvent, preferably forms a porous layer having the silica/alumina composite particles bound by the binder (hereinafter referred to as a composite particle layer).
In the present invention, the xerogel used for the composite particle layer is required to have an average pore radius of at least 6.0 nm. The xerogel is obtained by removing the solvent from the silica/alumina composite sol. The pore characteristics are measured by a nitrogen absorption desorption method. The average pore radius is a value obtained by calculation by (2V/A×10
3
(nm), where V is the total pore volume (cm
3
/g) and A is the specific surface area (m
2
/g). If the average pore radius of the xerogel obtained by removing the solvent from the silica/alumina composite sol, is less than 6.0 nm, the ink absorptivity of the composite particle layer tends to be inadequate, such being undesirable. The average pore radius of the xerogel is preferably within a range of from 6.0 to 15 nm, more preferably from 6.5 to 12 nm, particularly preferably from 7.0 to 10 nm.
The specific surface area of the xerogel is preferably from 50 to 200 m
2
/g. If the specific surface area is smaller than 50 m
2
/g, not only the fixing property of the dye in the ink tends to be poor, but also the glossiness and the transparency of the composite particle layer tend to be poor, and it tends to be difficult to obtain a recording medium having a high color density and glossiness. Further, if the specific surface area exceeds 200 m
2
/g, it tends to be difficult to obtain a large average pore radius, and it tends to be difficult to obtain a recording medium having good ink absorptivity. A more preferred range of the specific surface area is from 60 to 140 m
2
/g. By adopting the specific surface area within such a specific range, it is possible to obtain a recording medium which is excellent in glossiness and color density and which is excellent also in ink absorptivity.
In the present invention, the composite particle layer is formed on the ink receiving layer, whereby a recording medium excellent in ink absorptivity, image color density, water resistance, scratch resistance and glossiness, can be obtained. In particular, it is possible to obtain a recording medium of a high quality having a high color density and high glossiness, which is free from beading in a printing test which will be described hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
Not Applicable
DETAILED DESCRIPTION OF THE INVENTION
Now, the present invention will be described in detail with reference to the preferred embodiments.
In the present invention, the silica/alumina composite sol is preferably a colloidal solution obtained by adding to a silica sol an aluminum salt which shows acidity when dissolved in water, wherein the average particle size of agglomerated particles is from 50 to 200 nm. If the aver
Fujii Hiroyuki
Nakahara Katsumasa
Nakao Takuya
Asahi Glass Company Limited
Meier Stephen D.
Shah Manish
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