JPH0120995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a printing sheet that forms characters and images by flying minute droplets of ink, and is particularly suitable for forming characters and images in multicolor recording. This invention relates to a method of manufacturing a photographic printing sheet.

In recent years, the inkjet recording method has been used for a wide range of applications, including kanji, because it is high speed, high resolution, low noise, easy to print in multiple colors, has great flexibility in recording patterns, and does not require development or fixing. It is rapidly becoming popular for hard copies of color graphic information and for many other uses.

Furthermore, attempts have been made to utilize the ability to use various ink liquids and the great flexibility of recording patterns to apply it to fields such as multicolor printing and color photographic images, such as posters.

High-quality paper and coated paper used for general printing, as well as baryta paper and resin-coated paper used for photographic bases, have extremely poor ink absorption. remains on the surface for a long time,
If the recording surface is rubbed due to touching a part of the device, being touched by the operator, or continuously ejected sheets overlapping, the ink remaining on the surface may cause the image to be formed slowly. Get dirty. In addition, in multicolor recording, two or more colors of ink may overlap on the same surface, and in areas where the ink dot density is high, the ink may mix without being absorbed, resulting in problems such as decreased color quality or bleeding. There is no practical use. Furthermore, images formed with water-based inks lack gloss, and if exposed to water, etc., they may dissolve again. That is unsatisfactory.

Several proposals have been made to solve these problems. For example, JP-A-1983-
No. 53591 discloses a recording paper in which a water-soluble salt of a metal is applied to the surface on which recording is performed. Further, JP-A-56-84992 discloses an inkjet recording method in which printing is performed on a recording medium containing a polycationic polymer electrolyte on the surface using an aqueous ink containing a water-soluble direct dye or an acidic dye.
Furthermore, Japanese Patent Application Laid-Open No. 55-150396 discloses a method for making inkjet recording waterproof by applying a water-resistance agent that forms a lake with the dye in the water-based ink after inkjet recording using a water-based ink. After inkjet recording with water-based ink on an inkjet recording sheet coated with water-soluble polymer,
A method for making an inkjet recording sheet waterproof by applying a waterproofing agent that makes the water-soluble polymer insolubilized has been disclosed.

Further, JP-A-55-150370 discloses an inkjet recording method in which inkjet recording is performed on synthetic pulp paper and then the synthetic pulp is melted by heat treatment of the synthetic pulp paper.

Further, JP-A-55-61494 discloses a non-impact recording method in which toner is attached to an image formed on the surface of a recording medium using printing ink. Further, JP-A-55-11829 discloses an inkjet recording sheet having two or more ink absorbing layers and having an opacity of 55.0 to 97.5%.

However, JP-A-55-53591, JP-A-56
The technical idea represented by No. 84992 and Japanese Unexamined Patent Publication No. 150396 is to improve water resistance by making the dye in the ink poorly soluble using a substance contained in the recording paper or a substance applied after inkjet recording. Although it is possible to obtain some improvement, it is not satisfactory.

Furthermore, the technical idea found in JP-A-55-15037 and JP-A-56-58869 is to make the ink-receiving surface itself water-resistant after inkjet recording in order to obtain the desired water resistance and surface gloss. This method requires a fixing step after inkjet recording, making the process complicated. Furthermore, the technical idea found in JP-A No. 55-61494 and other publications attempts to obtain water resistance, gloss, etc. by replacing water-based ink with other pigments, but this is also considered to be a type of developing and fixing process. This reduces the simplicity that characterizes inkjet recording. Therefore, there has been a demand for a recording sheet that solves these problems and has the above-mentioned characteristics.

One object of the present invention is to have good ink absorption;
An object of the present invention is to provide a method for manufacturing a printing sheet having a multicolor inkjet recorded image with high resolution, good color reproducibility, and color density.

Another object of the present invention is to provide a method for producing a printing sheet which has a glossy recorded image with good water resistance and weather resistance after inkjet recording.

For these purposes, on one side of the transparent support, the refractive index
Provided with at least one ink-receiving layer including an adjacent ink-receiving layer containing one or more pigments selected from calcium silicate, basic magnesium carbonate, and synthetic silica as a main component of 1.55 or less, and after inkjet recording on the ink-receiving layer. This was achieved by bringing the ink-receiving layer into close contact with another supporting surface.

According to the present invention, there is provided a printing sheet characterized in that an image formed by ink that has permeated into the ink receiving layer adjacent to the transparent support can be viewed from the side of the transparent support. Furthermore, after inkjet recording on an inkjet recording sheet, by bringing it into close contact with another supporting surface, especially a sheet-like white opaque supporting surface, the recorded image is sandwiched from both sides, and oil and sweat from hands are removed when handled by a person. The image is completely protected from stains caused by accidental water splashes, etc.
A printing sheet having a glossy surface and a recorded image with good water resistance and weather resistance can be obtained.

The ink-receiving layer adjacent to the transparent support is an ink-receiving layer that is mainly composed of a pigment with a refractive index of 1.55 or less, which does not hide the dye that has penetrated into the ink-receiving layer, and is attached to the transparent support with an adhesive or the like. This is a layer provided.

When inkjet ink is injected onto an inkjet recording sheet prior to manufacturing the photographic sheet of the present invention, the ink penetrates into the voids in the ink receiving layer and forms a transparent support mainly composed of a pigment with a refractive index of 1.55 or less. It reaches and is retained by an adjacent ink-receiving layer to form an image.

Conventionally, in the inkjet recording method in which ink is jetted to obtain a recorded image, the recorded image was viewed from the side from which the ink was jetted, so increasing the ink absorption ability allows the ink to penetrate deeper, resulting in clearer tones. In addition, if the ink remains on the surface too much, the absorption capacity will be insufficient, so by balancing these factors, we can ensure ink jet suitability according to the application, but the dye and vehicle in the ink Methods such as providing a coating layer that has the ability to separate and adsorb have been used. In the present invention, the image formed by the ink that has penetrated deeply and reached the ink-receiving layer adjacent to the transparent support is viewed through the transparent support. By using the idea that the back side of the recording sheet is the front side, we are freed from the painstaking efforts to keep the dye, which previously penetrates deeply, on the surface, so the ink absorption capacity of the outermost layer is sufficient. The more easily it can be applied and the higher its absorption capacity is, the more suitable it is for the present invention. Furthermore, since the recorded image is viewed with the support side as the surface, it has excellent gloss and water resistance.

In the present invention, as described above, the ink jetted into the ink receiving layer is absorbed and permeated, and the refractive index is 1.55.
Since the image that has reached the ink-receiving layer made of the following pigments is viewed from the support side, the image becomes a mirror image.
Therefore, in order to form a normal recorded image, it is necessary to make the image itself jetted onto the ink-receiving layer a mirror image.

When the outermost layer is an ink-receiving layer adjacent to the transparent support referred to in the present invention, that is, when the ink-receiving layer is composed of one layer, the refractive index of the pigment constituting the ink-receiving layer is 1.55 or less. It is necessary that In addition, when the ink-receiving layer consists of two or more layers, the main pigment in the bottom layer, that is, the layer adjacent to the transparent support, must have a refractive index of 1.55 or less, but the other layers must have a refractive index of 1.55 or less. There is no need to pay attention to the refractive index of the pigment, and it is also possible to impart other properties such as absorption capacity, resolution, whiteness, and opacity. In particular, the layer provided on the ink-receiving layer formed of a pigment with a refractive index of 1.55 or less is preferably whiter and more opaque, and usually has a whiteness of 60% or more, particularly preferably 70% or more. Furthermore, the more opaque the overall image, the clearer the image, so the whiteness measured from the support side is 60.
It is also possible to use the uppermost layer as a colored ink-receiving layer as long as it does not exceed %.

The main pigment of the ink-receiving layer adjacent to the transparent support must have a refractive index of 1.55 or less, and the reason for this is that the image formed on the ink-receiving layer can be viewed from the transparent support side of the present invention. This is caused by
In other words, the ink that has penetrated into the ink-receiving layer is
It reaches the lowest layer, a layer consisting of a main pigment with a refractive index of 1.55 or less adjacent to the transparent support, where it is retained and forms an image. At this time, the stronger the hiding power of the pigment, that is, the higher the refractive index, the less clear the tone of the image viewed through the transparent support, and the lower the color reproducibility.

The ink-receiving layer referred to in the present invention is capable of absorbing ink droplets sprayed and attached to the surface of the ink-receiving layer through minute voids. It refers to a coating layer provided on a support mainly consisting of pigment and adhesive. Further, the ink-receiving layer adjacent to the support means the ink-receiving layer consisting of one or more layers, the lowest layer, that is, the layer closest to the support. In this case, one of the layers is an ink-receiving layer adjacent to the support.

Pigments with a refractive index of 1.55 or less used in the present invention include calcium silicate, basic magnesium carbonate, and synthetic silica, which can be used alone or in combination.

The synthetic silica referred to in the present invention refers to so-called white carbon such as metathesis precipitation products such as thermal decomposition of silicon tetrachloride, acid of sodium silicate, carbon dioxide, ammonium salt, etc., thermal decomposition of sodium silicate with acid, etc. By gelling the silica sol obtained through the exchange resin layer or colloidal silica obtained by heating and aging this silica sol, and changing the formation conditions, primary particles ranging from several millimicrons to several tens of millimicrons can be bonded with siloxane. silica gel, which has become three-dimensional secondary particles, as well as so-called synthetic molecular sieves produced by heating silica gel, sodium silicate, sodium aluminate, etc. as starting materials at 80°C to 120°C, and carbon dioxide. It is a synthetic silicon compound mainly composed of silicon.

In the present invention, the above-mentioned objective can be achieved with only the ink-receiving layer made of the main pigment with a refractive index of 1.55 or less, but a recording medium in which the ink-receiving layer is simply provided on a transparent sheet has low opacity, and the back side Because the color is transparent, the white background is dull and appears dark. Therefore, a white ink receiving layer is further provided on the ink receiving layer to increase the whiteness by 60% or more, preferably 70%.
% or more is desirable. As the white ink-receiving layer with a whiteness of 60% or more, a white pigment normally used for coating paper can be used. Examples of white pigments include clay, talc, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, satin white,
Aluminum silicate, aluminum hydroxide, silicon oxide, calcium silicate, diatomaceous earth, lithopone, urea-formalin resin, plastic pigments, etc. are used alone or in a mixture of two or more. Particularly desirable are calcium carbonate, titanium oxide, zinc oxide, silicon oxide, urea-formalin resin, and plastic pigments.

Furthermore, it is also possible to add a small amount of fluorescent dye, coloring dye, etc. to make it look whiter.

It is also possible to further provide a white, black, or colored colored ink receiving layer on the white ink receiving layer, and in this case, the whiteness measured from the support side should not be less than 60%. , it is possible to obtain a writing medium with a clearer image. The colored ink receiving layer may be the pigment used in the white ink receiving layer, a colored dye or a colored pigment may be added thereto to form a colored layer, or a colored pigment, carbon powder, etc. may be used alone. be.

The whiteness referred to in the present invention was measured using a Hunter colorimeter according to the method of JIS P8123. In other words, use a blue filter with a dominant wavelength of 457 mμ, prepare several samples to be measured, overlap them so that the light does not pass through but reflects 100% when overlapping them, and the incident light hits the support side. It is irradiated and measured as follows.

Examples of adhesives for the coating layer include starches such as oxidized starch, etherified starch, ester starch, and dextrin, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, caine, gelatin, soybean protein, polyvinyl alcohol and its derivatives, anhydrous Conjugated diene polymer latex such as maleic acid resin, ordinary styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester , vinyl polymer latices such as ethylene-vinyl acetate copolymers, functional group-modified polymer latexes using monomers containing functional groups such as carboxyl groups of these various polymers, and thermosetting synthetic resin systems such as melamine resins. An adhesive or the like is used.

These adhesives are 2 to 30 parts per 100 parts of pigment.
part, preferably 5 parts to 20 parts.

Furthermore, if necessary, pigment dispersants, thickeners, flow modifiers, antifoaming agents, foam inhibitors, mold release agents, coloring agents, etc. may be appropriately added without any problem as long as the properties are not impaired.

The coating machine of the present invention includes any blade coater, air knife coater, roll coater, brush coater, curtain coater, chain coater, bar coater, gravure coater, etc. that are generally used in the production of pigment-coated paper. can also be applied.

After coating, the coated sheet is dried by a conventional drying method such as a gas heater, an electric heater, a steam heater, or a hot air heater.

The coating layer may be applied in the required amount at one time, or may be applied in the required amount by overcoating two or more times.

The support used in the present invention can be cellophane, glass, thermoplastic synthetic resin film, etc., and thermoplastic resin films are usually transparent sheets such as polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, etc. is used. Furthermore, in order to improve the adhesion between these sheets and the ink-receiving layer, corona discharge treatment, other general treatments, or a clear subbing layer can be provided. In this case, the undercoat layer is preferably as transparent as possible, and a resin layer such as gelatin or nitrocellulose is usually used. Sheets that simply have a coating layer on the support have poor smoothness;
The image after multicolor recording using inkjet does not look very good. Therefore, as mentioned above, after coating and drying, it is possible to improve the finish of the inkjet image by passing it between roll nips under heat and pressure using, for example, a super calender or gloss calender to give the inkjet image smoothness.

The supporting surface that is in close contact with the printing surface used in the present invention can be any solid material with a smooth surface.
Examples include walls, glass plates, plastic products, metal products, polymer films, paper, etc., and polymer films, synthetic papers, paper, metal foils, etc. that can be formed into sheets are particularly suitable.

Generally known bonding methods such as adhesives, pressure-sensitive adhesives, dry lamination, etc. can be used to bring the printing surface into close contact with the supporting surface.

The present invention will be described below with reference to examples, but it is not limited to these examples. In addition, parts and percentages shown in the examples mean parts by weight and percentages by weight.

Example 1 A coating solution with a solid content of 20% consisting of 15 parts of polyvinyl alcohol and 100 parts of colloidal silica (refractive index 1.45) was applied to a corona-treated 75 μm polyester film so that the solid content was 15 g/m ² on one side. was applied with an air knife coater. This was used as the inject recording sheet of Example 1.

Example 2 A coating liquid with a solid content of 20% consisting of 100 parts of titanium oxide and 10 parts of polyvinyl alcohol was applied onto the ink receiving layer of the inkjet recording sheet of Example 1 so that the solid content was 3 g/m ² . The inkjet recording sheet of Example 2 was prepared by coating with an air knife coater.

Example 3 Urea-formaldehyde resin 100 was applied on the ink-receiving layer of the inkjet recording sheet of Example 1.
An inkjet recording sheet of Example 3 was prepared by applying a coating liquid with a solid content of 15%, consisting of 10 parts of oxidized starch and 10 parts of oxidized starch, to a solid content of 3 g/m ² using an air knife coater.

Example 4 A coating liquid consisting of 80 parts of calcium carbonate, 20 parts of carbon black, and 8 parts of polyvinyl alcohol was further added to the ink receiving layer of the inkjet recording sheet of Example 2 so that the solid content was 3 g/m ² . The inkjet recording sheet of Example 4 was prepared by coating with an air knife coater.

Example 5 90 parts of silica gel with an average particle size of 20 μm (refractive index 1.45)
A coating solution with a solid content of 20% consisting of 10 parts of calcium carbonate and 30 parts of polyvinyl alcohol has a solid content of 15 g/m ²
The inkjet recording sheet of Example 5 was prepared by coating it on a 50 μm polyester film provided with a hydrophilic undercoat layer so that the inkjet recording sheet of Example 5 was obtained.

Using the inkjet recording sheets of Examples 1 to 5, images were drawn by ejecting cyan, magenta, yellow, and black inks from four inkjet guns with nozzle diameters of 70 microns, and the ink was received after printing. An adhesive sheet was pasted on the surface. The obtained printing sheet exhibited a sufficiently satisfactory color density when viewed from the polyester film side, and the spread of the ink dots was 190 to 210 microns in diameter, indicating sufficient resolution.

Comparative Example 1 Same corona treatment as used in Example 1
75μm polyester film, 100 parts of Ancilex (refractive index 1.62), polyvinyl alcohol
Apply a coating solution of 20% solids consisting of 15 parts to one side with a solids content.
It was applied using an air knife coater to give a coating weight of 15 g/m ² . This was used as the inkjet recording sheet of Comparative Example 1.

Comparative Example 2 An in-jet recording sheet of Comparative Example 2 was obtained in exactly the same manner as Comparative Example 1 except that zinc oxide (refractive index 2.37) was used in place of the ancillex used in Comparative Example 1.

When an inkjet image was drawn using the inkjet recording sheets of Comparative Examples 1 and 2 under the same conditions as Examples 1 to 5 and viewed from the polyester film side, the resolution was almost the same as that of the example. , the color density decreased and the image became whitish, muddy and dull.

Claims (1)

[Scope of Claims] 1. At least an adjacent ink-receiving layer containing at least one pigment selected from calcium silicate, basic magnesium carbonate, and synthetic silica with a refractive index of 1.55 or less on one side of the transparent support. 1. A method for manufacturing a printing sheet, which comprises providing one ink-receiving layer, and after recording an ink jet on the ink-receiving layer, the ink-receiving layer side is brought into close contact with another supporting surface. 2. The method for manufacturing a photographic sheet according to claim 1, wherein the supporting surface is the surface of a sheet-like formation.