JPH1199741A - Inkjet recording sheet - Google Patents

Abstract

(57) [Summary] In an ink jet recording sheet to be recorded using a water-based ink, ink absorption is ensured, and the background color and the like are limited to only necessary recording portions without using a water-based ink for ink jet recording. An ink jet recording sheet that can be used to reduce the amount of ink used and greatly reduce printing time. An ink jet recording sheet provided with an ink receiving layer on at least one surface of a support, and printing on the surface of the ink receiving layer with an oil-based ink, wherein the printing is performed by a random dot printing method. In addition, the ink jet recording sheet is characterized in that the dot area coverage of the oil-based ink is 70% or less. Preferably, the unit dot diameter of the oil-based ink is 50 microns or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet, and more particularly to an ink jet recording sheet having an oil-based ink printed on an ink receiving layer by a random dot printing method.

[0002]

2. Description of the Related Art Ink-jet recording is a method in which fine droplets of ink are made to fly and adhere to a recording sheet such as paper according to various operating principles, thereby recording images and characters. It has features such as easy multi-coloring, great flexibility in recording patterns, and no need for development-fixing. It has rapidly spread in various uses as a recording device for various figures and color images including Chinese characters. I have. Further, an image formed by the multi-color ink jet system can obtain a record comparable to multi-color printing by a plate making system or printing by a color photographic system. In addition, in applications requiring a small number of copies, it is being widely applied to the field of full-color image recording because it is less expensive than the photographic technique.

As a recording sheet applicable to the ink jet recording system, high quality paper or coated paper used for lithographic printing, letterpress printing, gravure printing, etc. is used to obtain good image quality from the viewpoint of an ink jet recording apparatus and ink composition. How to get it has been considered. However, due to higher speed of inkjet recording, higher quality of required images, expansion of applications, etc.,
In order to satisfy these demands, it has become difficult only to respond to the recording apparatus and ink composition.

One of the characteristics required for the recording sheet is that the ink absorbing property is fast as the ink jet recording speed is increased. When the ink absorbency decreases, the ink diffuses to a portion other than the printing portion, and the sharpness decreases due to the enlargement of the dot diameter, and the white paper portion is contaminated by the ink called background smear. Further, this phenomenon becomes remarkable in a portion where ink overlaps. Another requirement is that print dots are not unnecessarily diffused as the quality of the image increases.
Although the dot diameter also depends on the recording apparatus, if the ink spreads more than necessary after landing on the recording sheet, the color and sharpness are reduced, resulting in a blurred image. Further, it is also a necessary requirement that there is no influence of the use environment with the expansion of the use, and that the image quality does not change over time. For example, excellent light resistance, water resistance, and ozone resistance are required.

Several proposals have hitherto been made in response to such demands. In order to improve the ink absorption and prevent the diffusion of print dots, a method of providing an ink receiving layer on a support (JP-A-52-9074, JP-A-58-72495, etc.) Focusing on the fact that the distribution state of the dye component affects the color and sharpness, a method using a specific agent that adsorbs the dye component (JP-A-55-144)
No. 172). In order to improve light resistance, water resistance, and ozone resistance, a basic oligomer may be contained (Japanese Patent Application Laid-Open No. 60-11389), and polyvinylamine may be added to the coating layer in or on the substrate. The use of a polymer (JP-A-64-8085) and the like are disclosed.

However, while the demands for these characteristics are gradually becoming higher and stricter, an ink-jet recording apparatus is inexpensive and has excellent image reproducibility such as sharpness and color reproducibility and color reproducibility at a personal computer level. Because it can be easily obtained, the inkjet recording device has changed from a special recording device used for a specific person to a general-purpose recording device, and the obtained image can also be printed or photographed. Because of the availability of similar products, they are increasingly used instead of simple printing.

[0007] Further, with the diversification of uses, it is used for posters and POP arts, or provided with an adhesive layer on the back surface, for price display labels, product display (barcode) labels, quality display labels, For label applications such as weighing display labels and advertising labels (stickers), it adheres well to a wide range of adherends, and because it is easy to apply, heat-sensitive properties, magnetic properties, Since it becomes possible to add a composite function by laminating a sheet or the like having suitability for offset printing, the application to tickets, commuter passes, various cards, and the like is expanding.

[0008] Ink jet recording inks are classified into a solvent type and an aqueous type. However, water-based inks are often used due to their price, safety, ease of handling, and the like. Recording applications are expanding, and in such applications, the printing screen area is large, so that processing time and printing time of a computer are required, and there has been a problem that workability is significantly deteriorated. In addition, since the printing area is large, the amount of ink used inevitably increases, and there is a problem that the running cost increases.

To solve such a problem, Japanese Patent Application Laid-Open No.
No. 07 discloses that multiple copies are printed with oil-based ink using a plate-making method for partial images whose image quality is important and can be printed in large quantities, and for partial images that have a large print area and can be printed in large quantities. For a partial image in which a different image is printed for each small amount, an ink jet recording method is used in which a small number of copies are printed by an ink jet recording method in an area where the oil-based ink transfer area occupying 70% or less of a unit dot area of the ink jet recording. It has been disclosed.

[0010]

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide an ink jet recording sheet which is recorded using an aqueous ink, to ensure ink absorbency and sharpness of a recorded image, and to provide a background color and the like. An object of the present invention is to provide an ink jet recording sheet which can be used only for a necessary recording portion without using an aqueous ink for ink jet recording, thereby reducing the amount of ink used and greatly shortening the printing time.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have taken advantage of the advantages of the conventional plate-making printing method and ink-jet recording to obtain a background color or the like using oil-based ink. It has been found that the problem can be solved by performing inkjet recording with an aqueous ink on an inkjet recording sheet printed by a specific printing method.

That is, the present invention relates to an ink jet recording sheet having an ink receiving layer provided on at least one surface of a support and printing the surface of the ink receiving layer with an oil-based ink, wherein the printing is performed by a random dot printing method. An ink jet recording sheet characterized in that the area coverage of dots with the oil-based ink is 70% or less.

The unit dot diameter of the oil-based ink for random dot printing is preferably 50 microns or less, more preferably 5 microns to 30 microns, and even more preferably 8 microns to 25 microns. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides an ink receiving layer provided on at least one surface of a support, wherein the surface of the ink receiving layer is printed with an oil-based ink by a random dot printing method, and a dot is formed by the oil-based ink. Coverage area ratio of 7
0% or less, the inkjet recording sheet has excellent absorbability of the aqueous ink for inkjet recording, has excellent sharpness of the recorded image, and can be used for inkjet recording even in large-format printing. An ink jet recording sheet that can reduce the consumption of ink for printing and can shorten the printing time.

In the ink jet recording sheet of the present invention, the ink receiving layer is a layer that absorbs and retains the aqueous ink when it lands, or a layer that is transmitted and further conveyed to the lower absorbent layer. A water-soluble resin is applied to the surface of a support that has various functions on a support called a coat type that has a layer mainly composed of a hydrophilic resin that has a function of taking in, or a surface press that is mainly composed of wood fiber by a size press or the like. Refers to a general paper type ink-receptive surface layer applied or impregnated.

The support that can be used in the present invention is, for example, a resin film such as a polyester film, a polyolefin film, or polyvinyl chloride. Paper such as plain paper, coated paper, and tracing paper. Resin-coated paper, synthetic paper, adhesive paper, adhesive film, etc. are used, but glass,
The support is not particularly limited as long as it can be provided with an ink receiving layer, such as an aluminum foil, a vapor-deposited paper, a vapor-deposited film, a nonwoven fabric, a leather product, and a ceramic product.

The ink-receiving layer is provided on at least one side of the support.
It may be provided on both sides of the support.

The thickness of the support used in the present invention does not need to be particularly limited. However, when a resin film, a resin-coated paper, a synthetic paper, or the like is used as the support, it is difficult to handle the support.
Those having a thickness of about 300 μm are preferred.

When paper is used as the support used in the present invention, commonly used paper can be used. As the pulp constituting the paper, natural pulp, recycled pulp, synthetic pulp and the like may be used alone or in combination of two or more. This paper contains sizing agents, paper strength enhancers, fillers, antistatic agents, fluorescent whitening agents,
Additives such as dyes are blended. Further, a hydrophilic resin such as starch or polyvinyl alcohol, a surface sizing agent, a surface paper strength enhancer, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be coated on the surface.

In addition, paper having improved surface smoothness during or after papermaking, or after providing a coating layer on the surface by a size press or the like, and compressing by applying pressure with a calendar or the like. But the basis weight is 30-300
g / m ² is preferred.

When the coated paper is used as the support, a generally used coated paper can be used. The material used for the coating layer of the coated paper is not particularly limited as long as it is a material generally used in the papermaking industry. Diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, Pigments such as zinc oxide, silicon dioxide, aluminum hydroxide, and urea-formalin resin, water-soluble binders such as starch and polyvinyl alcohol, latexes, surfactants, ultraviolet absorbers, fluorescent brighteners, dyes, and the like are used. May be.

The whiteness of the paper is measured according to JIS-P-812.
If the Hunter whiteness measured in Step 3 is 65% or more, the whiteness is high and a high-quality ink jet recording paper can be obtained. However, the whiteness required according to the purpose is different, and the brown color using unbleached pulp as a natural pulp is obtained. Base paper may be used. Further, paper colored with a coloring agent such as a dye may be used.

When a resin film is used as the support according to the present invention, the resin film may be any of a transparent film, a translucent film and a colored film, and may be subjected to treatment such as roll stretching, tenter stretching, and inflation stretching. May be subjected to an orientation treatment.

Further, in order to increase the whiteness of the resin film, a method of incorporating inorganic fine particles such as barium sulfate, titanium dioxide, calcium carbonate, silicon dioxide, aluminum oxide, kaolin, and talc into the resin film, and a method of using a white paint. A method of applying to the surface may be used.

Specific examples of the polyester include polyethylene terephthalate, polyethylene butylene terephthalate, polyethylene-2,6-naphthalate, and copolymers thereof with other components, but the present invention is not limited to these. is not.

Further, specific examples of the polyolefin include:
Examples include polypropylene and polyethylene, but the present invention is not limited to these. In addition, polyolefin includes low-, medium-, and high-density resins, and these may be used as a mixture.

Further, as a resin film, a void-containing film containing a large number of voids inside the film, for example, a foamed polyester film, can be used in order to provide cushioning and concealing properties.

The resin-coated paper refers to a paper in which one or both sides of the paper are coated with a resin such as polyolefin. The base paper for resin-coated paper is not particularly limited, and generally used paper can be used.

As the coating resin for the resin-coated paper, a polyolefin resin is preferable, and a polyethylene resin is particularly preferable. Further, low density polyethylene, medium density polyethylene, high density polyethylene or a mixture thereof can be used. The low-density polyethylene referred to here has a density of 0.
It is 915 to 0.930 g / cm ³ and is usually manufactured by a high-pressure method. On the other hand, high-density polyethylene has a density of 0.950 g / cm ³ or more, and is usually produced by a low-pressure method or a medium-pressure method. These polyethylene resins having various densities and melt flow rates can be used alone or in combination of two or more.

The structure of the resin layer of the resin-coated paper may be either a single layer or a multilayer of two or more layers. Also in this case, the above polyolefin resins can be used alone or in combination of two or more. Further, the respective layers of the multilayer may have different compositions or the same composition. As a method for forming a multilayer resin layer, any of a coextrusion coating method and a sequential coating method may be employed.

On the other hand, the resin layer of the resin-coated paper can also be formed by coating a latex having a film forming ability. For example, it can be formed by coating a latex having a low minimum film formation temperature (MFT) on a base paper for resin-coated paper and then heating the latex to a temperature not lower than the minimum film formation temperature.

The thickness of the coating resin layer of the resin-coated paper is not particularly limited, but it is generally coated to a thickness of 5 to 50 μm on the surface only or on both sides.

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate; fatty acid amides such as stearamide and arachidic amide;
Fatty acid metal salts such as zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, cobalt blue, ultramarine, cecilian blue,
Add appropriate combinations of various additives such as blue pigments and dyes such as phthalocyanine blue, magenta pigments and dyes such as cobalt violet, fast violet and manganese purple, fluorescent whitening agents, antioxidants, and ultraviolet absorbers. Can be.

As the pigment used for the support and the ink receiving layer, one or more known white pigments can be used. For example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic non-crystalline Amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite,
Inorganic pigments such as hydrohaloysite, magnesium carbonate and magnesium hydroxide, styrene-based plastic pigments, acrylic-based plastic pigments, polyethylene, microcapsules, and organic pigments such as urea resin and melamine resin can be used. Among the above-mentioned pigments, porous inorganic pigments are preferable, and examples thereof include porous amorphous synthetic silica, porous magnesium carbonate, and porous alumina. Particularly, porous synthetic amorphous silica having a large porous volume is preferable.

The ink receiving layer may be composed of two or more layers, and the surface to be printed must be selected according to requirements such as matte tone, art coat tone, cast tone, and film tone. Is not limited.

Further, an ink receiving layer can be coated on both sides of the support, and a back coat layer can be formed on the opposite side of the support on which the ink receiving layer has been coated to ensure curl aptitude and writability. May be applied. In addition, by adding a function combined with a sheet or the like having heat-sensitive properties, magnetic properties, and offset printing suitability via an adhesive layer, a ticket,
Application to commuter passes, various cards, etc. is also possible.

For the support and the ink receiving layer, adhesives such as polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, casein, gelatin, soybean protein, silyl-modified polyvinyl alcohol, etc. Conjugated diene copolymer latex such as maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; polymer or copolymer of acrylic ester and methacrylic ester, acrylic acid and methacrylic acid Acrylic polymer latex such as polymer or copolymer of vinyl; latex of vinyl polymer such as ethylene-vinyl acetate copolymer; or functional group by functional group-containing monomer such as carboxyl group of these various polymers Modified polymer latex Aqueous adhesives such as thermosetting synthetic resins such as melamine resin and urea resin; synthetic resin adhesives such as polymethyl methacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, and alkyd resin And
One or more of these can be used.

Apparatuses for coating or impregnating the support with the ink receiving layer include various types of blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, curtain coaters, short dwell coaters, size presses, sprays and the like. The device can be used on-machine or off-machine. After the ink receiving layer is applied, finishing may be performed using a calendar such as a machine calendar, a TG calendar, a super calendar, and a soft calendar.

The coating amount of the ink receiving layer provided on the support, in the case of general paper type ^{1g / m 2 ~6g / m 2} , when the coating type 4g / m ² ~30g / m ² is usually used .

The printing with the oil-based ink in the present invention is as follows.
Sheet-fed offset printing, offset rotary printing, gravure rotary printing, flexographic printing, screen printing, waterless printing,
Various printing methods such as letterpress printing are applicable.

The printing inks used for printing in the present invention include various oil-based inks such as lithographic inks, letterpress inks, letterpress rotary inks, rubber letterpress inks, tinplate inks, gravure inks, special gravure inks, news inks, and flexographic inks. The ink can be used as appropriate, and in consideration of the coating layer strength of the ink receiving layer of the ink jet recording sheet, the use of a soft ink having a low viscosity is preferable.

The printing method according to the present invention employs a random dot method (FM) in which unit dots are randomly arranged independently to express a gradation by the number of unit dots per a fixed area.
Use a printing plate made by the screen method). This is because while the conventional method expresses the gradation by the size of the dots, the random dot method expresses the gradation by the number of dots arranged at a fixed size at random, so it is recorded later. It is considered that the portion of the surface of the ink receiving layer that absorbs the aqueous ink for inkjet to be covered with the oil-based ink is finely and randomly distributed.

In the present invention, the area covered with the oily ink for printing must be 70% or less of the surface of the ink receiving layer. It is more preferably at most 50%, further preferably at most 30%. If the covering area ratio of the oil-based ink is more than 70%, the water-based ink jet ink to be subsequently injected will not have sufficient absorbency, and the sharpness of ink-jet recorded characters and images will be reduced.

When plate making is performed by the random dot method, the size of the unit dot affects the finish of printing and the absorbency of the aqueous ink for ink jet. In the present invention, the size of the unit dot is preferably 50 μm or less, preferably 5 μm or more and 30 μm or less, more preferably 8 μm or more, although it depends on the type of ink used and the amount of ink used. It is better to be less than 25 microns. If the unit dot size is 50 microns or more, the printed matter will feel rough.

In the present invention, the ink-jet ink is a recording liquid comprising a colorant, a liquid medium, and other additives.

Examples of the coloring agent include water-soluble dyes such as direct dyes, acid dyes, basic dyes, reactive dyes and food dyes.
Alternatively, a water-dispersible dye and a water-dispersible pigment can be used.

As the solvent for the aqueous ink, water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, Alkyl alcohols having 1 to 4 carbon atoms such as isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol and polypropylene glycol Polyalkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexyl Alkylene glycols having 2 to 6 alkylene groups such as lene glycol and diethylene glycol; lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl ether; No. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferable.

Other additives include, for example, a pH adjuster, a metal sequestering agent, a fungicide, a viscosity adjuster, a surface tension adjuster, a wetting agent, a surfactant, and a rust inhibitor.

The ink jet recording in the present invention is represented by a continuous method in which charged ink dots are constantly ejected and the ink dots are controlled by a magnetic field, a piezo method in which only the ink dots to be recorded on a recording sheet are ejected, and a bubble method. Printers and plotters using various systems such as an on-demand system can be applied.

The ink jet recording sheet according to the present invention may be used as any recording sheet using ink that is liquid at the time of recording. For example, a heat-fusible substance, a heat-fusible ink containing a dye or pigment as a main component, is applied on a thin support such as a resin film, a high-density paper, or a synthetic paper. An image-receiving sheet for thermal transfer recording, which is melted and transferred, an ink-jet recording sheet, which heats and melts a hot-melt ink to form fine droplets, and performs flight recording, an ink-jet recording sheet using an ink in which an oil-soluble dye is dissolved in a solvent, photopolymerization And an image receiving sheet corresponding to a photosensitive pressure-sensitive donor sheet using microcapsules containing a type monomer and a colorless or colored dye or pigment.

The common feature of these recording sheets is that the ink is in a liquid state at the time of recording. The liquid ink permeates or spreads in the depth direction or the horizontal direction of the ink receiving layer of the recording sheet until it hardens, solidifies or fixes. The above-mentioned various recording sheets require absorptivity according to each system, and the ink jet recording sheet of the present invention is used as the above-mentioned various recording sheets or a tack recording sheet obtained by tacking them. No problem.

Further, the ink jet recording sheet of the present invention is used as an electrophotographic recording sheet for heating and fixing an electrophotographic toner widely used in copying machines and printers, or as an electrophotographic recording sheet for labels. It does not matter.

[0053]

EXAMPLES The present invention will be described below with reference to examples of the present invention, but the present invention is not limited to these examples.
Further, "parts" and "%" shown in Examples are parts by weight and% by weight unless otherwise specified.

The evaluation was performed by the following method. 1) Ink absorptivity Ink jet printer (Deskjet 850C; manufactured by Hewlett-Packard Company) performs black ink characters and solid printing, and visually evaluates the ink transfer status when PPC paper is pressed against the solid printing surface immediately after printing.し な い indicates that no ink was transferred to the paper, 、 indicates that the ink was slightly transferred to the PPC paper, △ indicates that the ink was significantly transferred to the PPC paper, and x indicates that the ink was almost transferred to the PPC paper. . The properties of the ink jet recording sheet need to be evaluated as ◎ or ○. 2) Sharpness Characters and solid printing of black ink are performed with an ink jet printer (Deskjet 850C; manufactured by Hewlett-Packard Company), and the sharpness of the printed characters is visually evaluated. A sample having slight edge bleeding but not significantly affecting the sharpness was evaluated as ○, a character having bleeding of the edge of the character and capable of writing sharply was evaluated as △, and a character having extremely poor bleeding of the edge of the character and unclear was evaluated as ×. In addition, as the characteristics of the ink jet recording sheet,
Or evaluation of ○ is required. 3) Roughness of the printed surface Observation of the printed surface of the ink jet recording sheet printed with the oil-based ink was performed. And those that did not feel roughness at all were evaluated as ◎.

Examples 1 to 4 and Comparative Examples 1 to 6 <Preparation of Support 1> LBKP having a freeness of 450 mlcsf
80 parts, pulp slurry consisting of 20 parts of NBKP having a freeness of 475 mlcsf, 10 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Industry Co., Ltd.) and amphoteric starch (trade name: Cato3210, manufactured by Oji National Co., Ltd.) as filler 0.8 parts, a sulfuric acid band 0.6 parts, and an alkyl ketene dimer type sizing agent (trade name: Size Pine K903, manufactured by Arakawa Chemical Co., Ltd.) 0.08 parts were added, and the mixture was paper-made with a fourdrinier paper machine. A support 1 of 70 g / m ² was prepared. The prepared substrate had a Steckigt sizing degree of 25.2 seconds.

<Coating of Ink Receiving Layer on Support 1> A cationic dye fixing agent (Smileds Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.) was applied to Support 1 prepared above using an on-machine size press. 10 parts, 9 of commercially available oxidized starch
6 g / m ² (both sides) of a composition having a solid content concentration of 5% consisting of 0 parts was applied to form an ink receiving layer, and an ink jet recording sheet 1 was prepared.

<Implementation of Printing> The above-mentioned ink jet recording sheet 1 was subjected to TR printing using a Roland offset printing machine.
Monochromatic printing was performed with ANS-GS cyan ink (Dainippon Ink) under the following conditions. A gradation expression using a random dot method with a unit dot diameter of 50 microns, with a dot area ratio (coverage area ratio) of 10% (Example 1), and thereafter, 30% (Example 2), 50% (Example 3), 70%
(Example 4), 80% (Comparative Example 1), 100% (Comparative Example 2)
An ink jet recording sheet on which printing was performed was prepared. In addition, a printing method of 150 lines / inch, which has been widely used, has a halftone dot area ratio (coverage area ratio) of 10% (Comparative Example 3).
Ink jet recording sheets were printed at 0% (Comparative Example 5) and 70% (Comparative Example 6).

Table 1 shows the evaluation results of Examples 1 to 4 and Comparative Examples 1 to 6.

[Table 1]

Examples 5 to 8 and Comparative Examples 7 to 12 <Preparation of Support 1> LBKP having a freeness of 450 mlcsf
80 parts, pulp slurry consisting of 20 parts of NBKP having a freeness of 475 mlcsf, 10 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Industry Co., Ltd.) and amphoteric starch (trade name: Cato3210, manufactured by Oji National Co., Ltd.) as filler 0.8 parts, a sulfuric acid band 0.6 parts, and an alkyl ketene dimer type sizing agent (trade name: Size Pine K903, manufactured by Arakawa Chemical Co., Ltd.) 0.08 parts were added, and papermaking was performed using a fourdrinier paper machine. With a press device, a liquid having a solid content concentration of 5% of commercially available oxidized starch was adhered to 5 g / m ² (both sides) to prepare a support ² having a basis weight of 180 g / m ² .

<Coating of Ink Receiving Layer on Support 2> 100 parts of synthetic amorphous silica (Fan Seal X37B: manufactured by Tokuyama Soda Co., Ltd.) was applied to Support 2 prepared above using an air knife coater. , Polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.), 30 parts, ethylene / vinyl acetate emulsion (Panflex OM60)
00: manufactured by Kuraray Co., Ltd.) and a cationic dye fixing agent (Sumireze Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.) by 30 parts was coated to a solid content of 9 g / m ^2. Thus, an ink jet recording sheet 2 was prepared.

<Implementation of Printing> The above-mentioned inkjet recording sheet 2 was subjected to TR printing using a Roland offset printing machine.
Monochromatic printing was performed with ANS-GS Veneer Ink (Dainippon Ink) under the following conditions. A halftone dot area ratio (coverage area ratio) of 10% in a gradation expression by a random dot method with a unit dot diameter of 30 microns (Example 5), and similarly, 30% (Example 6), 50% ( Examples 7), 70% (Example 8), 80% (Comparative Example 3), and 100% (Comparative Example 4) were printed to form ink jet recording sheets.
Also, a printing method of 150 lines / inch, which has been widely used in the past, in which the halftone dot area ratio (coverage area ratio) was 10% (Comparative Example 9), and similarly, 30% (Comparative Example 10), 50
% (Comparative Example 11) and 70% (Comparative Example 12) to prepare an ink jet recording sheet on which printing was performed.

Table 2 shows the evaluation results of Examples 5 to 8 and Comparative Examples 7 to 12.

[Table 2]

Examples 9 to 20, Comparative Examples 13 to 14 <Coating of ink receiving layer on support 2> The same support 2 as used in Examples 5 to 8 was synthesized using an air knife coater. 100 parts of amorphous silica (Fanseal X37B: manufactured by Tokuyama Soda Co., Ltd.), polyvinyl alcohol (P
VA117: 30 parts by Kuraray Co., Ltd., ethylene / vinyl acetate emulsion (Panflex OM600)
0: manufactured by Kuraray Co., Ltd.) and a cationic dye fixing agent (Sumireze Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.) by 30 parts was applied to a solid content of 9 g / m ^2. 100 parts of colloidal silica having an average particle diameter of 65 nm (Snowtex YL: manufactured by Nissan Chemical Industries, Ltd.) and styrene-butadiene latex (0693; average particle diameter of 135 nm: manufactured by Nippon Synthetic Rubber Co., Ltd.) as an adhesive Using 30 parts, a coating solution having a solid content concentration of 25% was prepared. This coating liquid was applied to the ink receiving layer surface by a roll coater so as to have a dry coating amount of 5 g / m ^2, and subjected to a soft calender treatment to prepare an ink jet recording sheet 3.

<Implementation of Printing> The ink jet recording sheet 3 was subjected to TR printing using a Roland offset printing machine.
Monochromatic printing was performed with ANS-GS yellow ink (Dainippon Ink) under the following conditions. The unit dot diameter is changed as shown in Table 3 and the halftone dot area ratio (coverage area ratio) is set to 30% in the gradation expression by the random dot method (Examples 9 to 18). Was set to 15 microns, and the halftone dot area ratio (coverage area ratio) was 50% (Example 1).
9), 70% (Example 20), 80% (Comparative Example 13),
An ink jet recording sheet printed as 100% (Comparative Example 14) was prepared.

Table 3 shows the evaluation results of Examples 9 to 20 and Comparative Examples 13 and 14.

[Table 3]

[0066]

As is clear from Tables 1 to 3, the ink jet recording sheet according to the present invention, which is printed with a coverage of 70% or less with an oil-based ink by the random dot printing method, is different from the ink jet recording sheet printed by the conventional method. In comparison, the ink absorptivity does not change and shows excellent performance in sharpness. Therefore, the ink jet recording sheet of the present invention that has been subjected to the random dot printing method can be used in exactly the same manner as a blank ink jet recording sheet, and since the background printing has already been performed, it is necessary to print that part with the ink jet ink. The purpose is achieved by printing only the necessary images without any problem, and the effect that the amount of ink used can be saved and the printing time can be extremely reduced can be obtained. Further, when the diameter of the unit dot is 50 μm or less, the printed surface is no longer rough, and a more favorable effect can be obtained.

Claims (4)

[Claims] An ink jet recording sheet comprising an ink receiving layer provided on at least one side of a support, and printing on the surface of the ink receiving layer with an oil-based ink.
An ink jet recording sheet, wherein halftone dots are formed by random dot printing in the printing, and a dot coverage ratio of the oil-based ink is 70% or less. 2. The ink jet recording sheet according to claim 1, wherein the unit dot diameter of the random dot printing oil-based ink is 50 μm or less. 3. The ink jet recording sheet according to claim 1, wherein the unit dot diameter of the random dot printing oil-based ink ranges from 5 to 30 microns. 4. The ink jet recording sheet according to claim 1, wherein the unit dot diameter of the oil-based ink for random dot printing is in a range of 8 to 25 microns.