Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-01-12
2003-04-22
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S331000, C428S500000
Reexamination Certificate
active
06551695
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ink-jet recording material, particularly to an ink-jet recording material which has photo-like high gloss, is excellent in ink-absorption capacity, and is improved in preservability after printing.
2. Prior Art
As a recording material to be used for an ink-jet recording system, a recording material which comprises a porous ink-receptive layer comprising a pigment such as amorphous silica, and a hydrophilic binder such as polyvinyl alcohol being provided on a support such as a usual paper or the so-called ink-jet recording sheet has generally been known.
There have been proposed recording sheets obtained by coating a silicon-containing pigment such as silica with a hydrophilic binder onto a paper support as disclosed in, for example, Japanese Provisional Patent Publications No. 51583/1980, No. 157/1981, No. 107879/1982, No. 107880/1982, No. 230787/1984, No. 204390/1985, No. 160277/1987, No. 184879/1987, No. 183382/1987, No. 11877/1989, and the like.
Also, in Japanese Patent Publication No. 56552/1991, Japanese Provisional Patent Publications No. 188287/1990, No. 81064/1998, No. 119423/1998, No. 175365/1998, No. 203006/1998, No. 217601/1998, No. 20300/1999, No. 20306/1999 and No. 34481/1999, U.S. Pat. No. 5,612,281, and EP 0 813 978 A, and the like, there have been disclosed ink-jet recording materials using synthetic silica fine particles prepared by a gas phase process (hereinafter referred to as “fumed silica”). The fumed silica is ultrafine particles having an average particle size of a primary particle of several nm to several tens nm, and has characteristics of giving high gloss and high ink-absorption properties. In recent years, a photo-like recording sheet has earnestly been desired and glossiness becomes more important. As such a recording material, there has been proposed a recording material in which an ink-receptive layer mainly comprising fumed silica is provided by coating on a water-proof support such as a polyolef in resin-coated paper (a polyolef in resin such as polyethylene, etc. are laminated on the both surfaces of paper) or a polyester film, etc.
However, in the porous recording material using inorganic fine particles such as the fumed silica, there is a problem that the printed image is likely discolored during storage. That is, discoloration due to light or a minute amount of a gas in air is likely caused. In particular, it is a more significant problem of discoloration due to a minute amount of a gas in air.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink-jet recording material which has photo-like high gloss and high ink-absorption capacity, and is improved in preservability.
The above objects of the present invention can be accomplished by an ink-jet recording material which comprises a support, and an ink-receptive layer containing fumed silica having an average primary particle size of 3 to 30 nm provided on the support, wherein said ink-receptive layer contains a cationic compound and at least one selected from the group consisting of a sulfur-containing compound having no mercapto group, an amine compound, an amino compound and a saccharide, and a pH of the surface of said ink-jet recording material is 3 to 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, the embodiments of the present invention are explained in detail.
The ink-jet recording material of the present invention is to absorb ink in voids formed by the fumed silica having an average primary particle size of 3 to 30 nm in the film, and to realize high ink-absorption capacity, it is necessary to heighten void volume. Thus, it is necessary to coat a relatively large amount of the fumed silica on the support, and when a hydrophilic binder is used, its amount is preferably reduced to heighten the void ratio.
The fumed silica to be used in the present invention is preferably contained in the ink-receptive layer in an amount of about 8 g/m
2
or more, more preferably in the range of about 10 to about 30 g/m
2
. If the amount is less than the above range, ink-absorption capacity is sometimes poor. An amount of the hydrophilic binder is preferably about 40% by weight or less, more preferably about 10 to about 30% by weight based on the amount of the fumed silica. By making the ratio of the hydrophilic binder as mentioned above, ink-absorption capacity is improved but preservability after printing, particularly gas resistance is likely lowered. These properties are simultaneously satisfied by the constitution of the present invention as defined above.
In the present invention, the fumed silica is preferably contained in the ink-receptive layer as a main component, i.e., it is preferably contained in an amount of about 50% by weight or more, more preferably about 60% by weight or more, further preferably about 65% by weight or more based on the total weight of the whole solid components in the ink-receptive layer. Fumed silica to be used in the present invention is also called to as the drying method silica, and the fumed silica can be generally prepared by a flame hydrolysis method. More specifically, it has been known a method in which silicon tetrachloride is burned with hydrogen and oxygen. In this method, silanes such as methyl trichlorosilane, trichlorosilane, etc., may be used alone in place of silicon tetrachloride or in combination with silicone tetrachloride. The fumed silica is commercially available from Nippon Aerosil K.K. (Japan) under the trade name of Aerosil, and K.K. Tokuyama (Japan) under the trade name of QS type, etc.
An average primary particle size of the fumed silica to be used in the present invention is 3 nm to 30 nm, particularly preferably 3 nm to 15 nm. More preferably, those having an average primary particle size of 3 to 15 nm and a specific surface area measured by the BET (Brunauer-Emmett-Teller) method of 200 m
2
/g or more. The BET method herein mentioned means one of methods for measuring a surface area of powder material by a gas phase adsorption method and is a method of obtaining a total surface area possessed by 1 g of a sample, i.e., a specific surface area, from an adsorption isotherm. As an adsorption gas, a nitrogen gas has frequently been used, and a method of measuring an adsorption amount obtained by the change in pressure or a volume of a gas to be adsorbed has most frequently been used. Most frequently used equation for representing isotherm of polymolecular adsorption is a Brunauer-Emmett-Teller equation which is also called to as a BET equation and has widely been used for determining a surface area of a substance to be examined. A specific surface area can be obtained by measuring an adsorption amount based on the BET equation and multiplying the amount with a surface area occupied by the surface of one adsorbed molecule.
In the present invention, as the hydrophilic binder to be preferably used with the fumed silica, conventionally known various binders can be used, and a hydrophilic binder which has high transparency and gives high permeability is preferably used. For using the hydrophilic binder, it is important that the hydrophilic binder does not clog the voids by swelling at the initial stage of permeation of ink. From this point of view, a hydrophilic binder having a relatively low swellability at around the room temperature is preferably used. A particularly preferred hydrophilic binder is a completely or partially saponified polyvinyl alcohol or a cationic-modified polyvinyl alcohol.
Among the polyvinyl alcohols, particularly preferred are those having a saponification degree of 80% or more, i.e., apartially saponified or completely saponified polyvinyl alcohol. Those having an average polymerization degree of 200 to 5000 are preferred.
Also, as the cationic-modified polyvinyl alcohol, there may be mentioned, for example, a polyvinyl alcohol having a primary to tertiary amino groups or a quaternary ammonium group at the main chain or side chain of the polyvinyl alcohol as disclosed in Japanese Provisional Pate
Ishimaru Tomoko
Kaneko Satoshi
Sakaguchi Hiroshi
Suzuki Yukihiro
Kelly Cynthia H.
Manelli Denison & Selter PLLC
Mitsubishi Paper Mills Limited
Shewareged B.
White, Jr. Paul E.
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