Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
1999-04-22
2001-05-22
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S195100, C428S345000, C428S3550EN, C428S3550AC, C428S522000, C522S090000, C522S093000, C522S095000, C522S096000, C522S097000, C522S098000, C522S139000, C522S140000, C522S141000, C522S144000, C522S146000, C522S174000
Reexamination Certificate
active
06235397
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high gloss printing sheet. More particularly, the present invention relates to a printing sheet provided with an electron beam-cured resin coating layer, arranged on the outermost surface of the sheet, having an enhanced compatibility with printing ink and exhibiting a high gloss before and after printing.
2. Description of the Related Art
It is known that a cast coated paper sheet having a high gloss is produced by coating an aqueous coating liquid containing, as principal components, a pigment and a binder on a front surface of a substrate paper sheet and the coated liquid layer is pressed onto a heating mirror surface of a casting base while the coated liquid layer still contains water and exhibits a plasticity, and is then dried to form a high gloss front coating layer. The conventional cast coated paper sheet is, however, not satisfactory in gloss and thus a new type of high gloss sheet is strongly demanded.
Also, when another coating layer is further formed on the back surface of the substrate sheet in the same conventional cast-coating method as mentioned above, since the back coating layer surface comes into contact with the heating mirror surface so as to rapidly evaporate away water from the back coating layer, the front coating layer is swelled and softened by the water vapor. The phenomenon usually causes the surface smoothness and gloss of the front coating layer to decrease and thus the clearness of ink images printed on the front coating layer surface to deteriorate.
The above-mentioned disadvantages of the conventional printing sheet can be solved by a laminate coating method in which a thermoplastic resin melt is formed into a film-like stream, the film-like resin melt stream is coated on a front surface of a substrate sheet, the resultant resin melt layer of the laminate is brought into contact with a mirror-casting face of a rotating metal drum under pressure and then cooled on the mirror-casting surface to solidify the resin layer and the resultant high gloss sheet is removed from the mirror-casting face.
Alternatively, a laminate sheet having a high gloss coating layer can be produced by a cast-electron beam-irradiation method in which a coating liquid containing an electron beam-curable unsaturated organic material is coated on a front surface of a substrate sheet, the resultant coating layer is brought into contact with a casting face of a casting sheet or a casting drum under pressure and an electron beam is irradiated to the coating layer so as to cure the coating layer.
The cast coated sheets produced by the above-mentioned methods have a satisfactory high gloss.
Nevertheless, these conventional sheets are unsatisfactory as printing sheets. Namely, the conventional cast-coated sheets have an unsatisfactory suitability for printing, especially an insufficient compatibility with printing ink, in other words an unsatisfactory ink-setting property.
Particularly, when a conventional electron beam-curable unsaturated organic compound is coated on the substrate sheet and cured by electron beam irradiation, the resultant resin coating layer consists of a dense film which has a poor compatibility with the ink and thus does not allow the ink to penetrate into the resin coating layer. Also, the conventional electron beam-cured resin coating layer exhibits a poor ink-setting property. Therefore, when, on the printed surface of the conventional printing sheet, another sheet is superposed, the ink located on the printed surface is easily transferred to and soils the back surface of the superposed sheet.
This problem is considered very difficult to solve.
Also, it is known that even when the conventional electron beam-curable unsaturated compound can form a cured resin coating layer having a good ink-setting property, the gloss of the cured resin coating layer is degraded by a printing operation.
Accordingly, there is a strong demand of providing a new type of high gloss printing sheet free from the above-mentioned disadvantages.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a high gloss printing sheet having a high gloss before and after printing and an enhanced suitability for printing, especially an excellent printing ink-setting property, and being useful for offset printing, gravure printing, and relief printing.
The above-mentioned object can be attained by the printing sheet of the present invention which comprises a substrate sheet, and
an outermost surface coating layer formed on a surface of the substrate sheet and comprising an electron beam-cured resin produced from an electron beam-curable organic material,
the electron beam-curable organic material comprising at least one member selected from reaction products of
(a) reaction products of (i) at least one member selected from straight and branched chain alkylene diol compounds having a number average molecular weight of 300 to 10,000 the alkylene group of which compounds has 15 or more carbon atoms, with (ii) at least one member selected from the group consisting of aromatic, cycloaliphatic and aliphatic polyisocyanate compounds, with
(b) at least one member selected from the group consisting of hydroxy acrylate compounds and hydroxymethacrylate compounds.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The inventors of the present invention energetically investigated a new type of high gloss printing sheet free from the above-mentioned disadvantages and discovered that the disadvantages can be eliminated by forming an outermost surface coating layer on a substrate sheet from a specific electron beam-curable unsaturated organic compound.
In the high gloss printing sheet of the present invention, a specific outermost surface coating layer is formed, on a surface of a substrate sheet, by an electron beam-cured resin produced from an electron beam-curable organic material.
The electron beam-curable organic material comprises at least one member selected from reaction products (A) of
(a) reaction products of (i) at least one member selected from straight and branched chain alkylene diol compounds having a number average molecular weight of 300 to 10,000, the alkylene group of which compounds (i) has 15 or more carbon atoms, with (ii) at least one member selected from the group consisting of aromatic, cycloaliphatic and aliphatic polyisocyanate compounds, with
(b) at least one member selected from the group consisting of hydroxyacrylate compounds and hydroxymethacrylate compounds.
It is known that polyurethane acrylate compounds and polyurethane methacrylate compounds are usable as electron beam-curable unsaturated organic compounds. However, it is quite new to utilize the specific unsaturated reaction products (A), to form an outermost surface coating layer on a surface of a substrate sheet, to provide a high gloss printing sheet having a high suitability for printing.
In the preparation of the reaction products (A), (i) at least one member selected from straight and branched chain alkyl diol compounds which have a long alkyl group with 15 or more carbon atoms, more preferably 30 to 350 carbon atoms, and a number average molecular weight of 300 to 10,000 is reacted with (ii) at least one member selected from the group consisting aromatic, cycloaliphatic and aliphatic polyisocyanate compounds.
The resultant reaction product (a) is further reacted with (b) at least one member selected from the group consisting of hydroxyacrylate compounds and hydroxymethacrylate compounds.
Conventional polyurethane acrylate or methacrylate compounds, which are produced by reacting polyesterurethanes or polyetherurethanes with hydroxy acrylate or methacrylate compounds, are known as electron beam-curable unsaturated organic compounds. The polyesterurethanes are obtained by reacting polyester-polyhydric alcohol compounds, which have been produced by reacting polybasic acids, for example, phthalic acid and succinic acid, with polyhydric alcohol compounds having a low molecular weight, for example, pentaerythritol, with
Kamiya Masahiro
Nagasaki Shinichi
Nakayama Yasufumi
Armstrong, Westermanm, Hattori, McLeland & Naughton, LLP
Chen Vivian
Oji Paper Co. Ltd.
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