1. Field of the Invention
The present invention relates to an ink jet recording medium suitable for printing with an ink jet recording ink and an apparatus for its treatment, as well as a printed product prepared by the treatment. By the present invention, it is possible to obtain an ink jet printed product which not only is free from printing irregularities or bleeding, but also has a high gloss and which is excellent also in water resistance, light resistance and scratch resistance.
2. Discussion of Background
Ink jet recording has been widely used in recent years as it is free from noise, capable of printing at a high speed and useful for e.g. terminal printers. Further, by using a plurality of ink nozzles, multicolor recording can thereby be easily carried out, and multi ink jet recording by various types of ink jet recording systems is practically carried out. Particularly, an attention has been drawn to an ink jet printer which is capable of accurately forming a complicated image at a high speed, as an output device for image information of e.g. letters or various designs prepared by computers and photographs. Application fields of ink jet printers which have been of particular interest in recent years, include, for example, large posters, displays, flags, etc. which can easily be prepared by means of large size ink jet plotters.
Ink jet recording media to be used in these fields are required to be not only of high quality but also aesthetically excellent and further, when used as e.g. large size posters for outdoor display, they are required to have excellent weather resistance and water resistance.
In an effort to satisfy such requirements, various improvements have been proposed from both aspects of the ink and the recording media.
In an ink jet recording system, it has been common to employ an ink having a dye or pigment dissolved or dispersed in an aqueous or organic solvent. Most popular is a water-soluble dye ink having various water-soluble dyes dissolved in water or in a mixture of water and an organic solvent. Such a water-soluble dye ink is excellent for the maintenance of an ink jetting head of an ink jet recording apparatus and excellent also in the color developing property or resolution after printing. However, it brings about a problem in water resistance of a recorded image, as it is water-soluble. Further, a water-soluble dye is poor in weather resistance by its nature (color change or fading of an image due to light, ozone, SOx, NOx, temperature or humidity), and accordingly, when the recording medium is displayed outdoor, there will be a drawback that the image undergoes color fading or color change quickly.
In order to overcome such drawbacks, many proposals have been made for recording sheets and recording methods so that a resin layer is provided on a porous ink-absorbing layer containing a pigment, and the resin layer is fused after printing with a water-soluble dye ink. JP-B-2-31673 discloses a combination of a pigment layer and a heat melting layer, and JP-A-8-2090, JP-A-9-104163 and JP-A-9-104164 propose a combination of a heat melting layer and a pigment layer employing an alumina hydrate. As a method for fusing the heat meltable resin layer after printing, various methods may be mentioned such as pressing it against a heated drum such as a ferrotype drier to be used for drying baryta photographic base paper, or passing it between a pair of rolls for pressing and heating. However, it is most common to press it against a heated flat metal roll for fusion. By this fusing treatment, a heat meltable resin layer is formed to secure water resistance, weather resistance, gloss or transparency. However, the performance is still inadequate, and further improvements have been desired. Further, the average particle size of the fine particles of the heat meltable organic polymer contained in the heat melting layer is fine, whereby the ink permeability is poor, and with respect to the printing property, a drawback such as flooding or bleeding of ink has not yet been completely overcome. Especially, there has been a problem that if it is tried to obtain adequate water resistance, scratch resistance of the surface of the recording medium tends to deteriorate.
It is an object of the present invention to provide an ink jet printed product which fully satisfies scratch resistance, light resistance, water resistance, an elimination of printing irregularities or bleeding, an apparatus for its preparation, and an ink jet recording medium suitable therefor.
One object of the present invention has been accomplished by an ink jet recording medium having the following structures.
1. An ink jet recording medium which comprises a support and a layer comprising fine particles of a thermoplastic organic polymer, formed on at least one side of the support, so that said fine particles of a thermoplastic organic polymer are dissolved or melted after ink jet recording to form a layer wherein said fine particles of a thermoplastic organic polymer are fused to one another, wherein said fine particles of a thermoplastic organic polymer have an average particle size within a range of from 1 to 20 xcexcm.
2. The ink jet recording medium according to Item 1, wherein an ink-absorbing layer comprising an inorganic pigment, is formed between the support and the layer comprising fine particles of a thermoplastic organic polymer.
3. The ink jet recording medium according to Item 2, wherein said inorganic pigment comprises a pigment having an average secondary particle size of at least 1 xcexcm and less than 5 xcexcm and a pigment having an average secondary particle size of at least 5 xcexcm.
4. The ink jet recording medium according to any one of Items 1 to 3, wherein the layer comprising fine particles of a thermoplastic organic polymer, contains colloidal silica.
5. The ink jet recording medium according to any one of Items 1 to 4, wherein the layer comprising fine particles of a thermoplastic organic polymer, contains a release agent.
6. The ink jet recording medium according to any one of Items 1 to 5, wherein said fine particles of a thermoplastic organic polymer are of a polyolefin resin.
7. The ink jet recording medium according to any one of Items 1 to 6, wherein the support is a waterproof support.
Another object of the present invention is accomplished by an apparatus for preparing an ink jet printed product having the following structures.
8. An apparatus for preparing an ink jet printed product, whereby, after carrying out ink jet recording on an ink jet recording medium which comprises a support and a layer comprising fine particles of a thermoplastic organic polymer, formed on at least one side of the support, said fine particles of a thermoplastic organic polymer are dissolved or melted to form a layer wherein said fine particles of a thermoplastic organic polymer are fused to one another, which comprises a step of heating the layer comprising fine particles of a thermoplastic organic polymer, and an impressing step of passing the recording medium between a pair of press rolls while the layer comprising fine particles of a thermoplastic organic polymer is still in a plastic state after the heating step, to transfer a shape of the roll surface to the layer.
9. The apparatus for preparing an ink jet printed product according to Item 8, wherein the temperature of the roll surface which contacts the layer comprising fine particles of a thermoplastic organic polymer in the impressing step, is lower than the temperature in the heating step.
10. The apparatus for preparing an ink jet printed product according to Item 8, wherein the heating step is a step of heating to a temperature of at least the minimum film-forming temperature (MFT) of said fine particles of a thermoplastic organic polymer, and the temperature of the roll surface in the impressing step is a temperature lower than MFT.
11. The apparatus for preparing an ink jet printed product according to any one of Items 8 to 10, wherein the heating means in the heating step is of a type to heat from the rear side of the support by a heat conduction system.
12. The apparatus for preparing an ink jet printed product according to any one of Items 8 to 10, wherein the heating means in the heating step is of a type to heat from the side of the layer comprising fine particles of a thermoplastic organic polymer by a radiation conduction system.
13. The apparatus for preparing an ink jet printed product according to any one of Items 8 to 10, wherein the heating means in the heating step is of a type to heat from the side of the layer comprising fine particles of a thermoplastic organic polymer by a convective heat transfer system.
14. The apparatus for preparing an ink jet printed product according to any one of Items 8 to 13, wherein the roll surface which contacts the layer comprising fine particles of a thermoplastic organic polymer in the impressing step, is a mirror-finished surface, a roughened surface or a surface having a patterned engraving.
Still another object of the present invention has been accomplished by an ink jet printed product having the following structure.
15. An ink jet printed product obtained by carrying out ink jet recording on an ink jet recording medium as defined in any one of Items 1 to 7, followed by treatment by an apparatus for preparing an ink jet printed product as defined in any one of items 8 to 14.