JP2001246831A - Ink jet printing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printing sheet being a micro-coating type ink jet printing sheet, generating no blur irregularity of ink, excellent in ink absorbability, imparting a printed image high in density and sharpness, reducing the deformation of a dot and enabling double-side printing. SOLUTION: In the ink jet printing sheet wherein printing surfaces are provided on both surfaces of raw paper, the raw paper is neutral paper containing a filler and a neutral internal size agent and the basis weight of a product after the coating of the raw paper is 100-250 g/m2 and Stockigt sizing degree of the product is 130-190 sec and the printing surface of the printing sheet is coated with fine particulate inorganic pigment of a composition based on alumina along the surfaces of the pulp fibers in an entangled state of the surface of the raw paper and the shape of the surface coated pulp fibers can be visually confirmed by a scanning electron microscope and the surface coating form of the pulp fibers is an almost perfectly coated state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet for ink-jet printing, and more particularly to a sheet for ink-jet printing. The present invention relates to an ink jet printing sheet capable of printing on both sides of a fine coating type with little print dot deformation.

In the ink-jet printing method, minute ink droplets are ejected by various operating principles such as electric-mechanical conversion, electric-heat conversion, and electrostatic attraction in the on-demand method, in a continuous method by charge control and pressure vibration. To print images, characters, etc. by attaching it to a printing sheet such as paper, etc., but it is easy to reduce noise, increase speed, and multicolor, and has great flexibility in printing patterns. Are widely used in various applications as a printing and recording device for various figures including kanji, full-color images, and the like. Further, it has become possible to obtain an image formed by the multi-color ink jet system, which is comparable to multi-color printing by the plate making system or printing by the color photographic system. Also, for on-demand printing applications that require a small number of copies, plate making and
Since it is cheaper than what is printed, it has been widely applied to the field of full-color image recording.

The printing sheet used in the ink jet printing system has been improved in terms of devices such as a printer head and ink composition so that high quality paper and coated paper for ordinary printing and writing can be used. Have been. However, with the improvement of the performance of ink jet printing and recording devices, such as high-speed, high-definition or full-color printers, and the expansion of applications, even higher printing suitability for printing sheets has been achieved.
Characteristics are required. That is, for the printing sheet, the density of the printing dots is high, the color tone is bright and brilliant, the ink absorption is fast, and even when the printing dots overlap, there is no outflow or bleeding of the ink,
The diffusion of print dots in the horizontal direction is not unnecessarily large, and the periphery is smooth and not blurred. In addition, when performing double-sided printing, ink does not strike through and is not affected by printing on the back surface It is required to have opacity.

[0004] In general, the form of the ink jet printing sheet is a plain paper type typified by high quality paper or bond paper or the like, and ink is received on a support such as paper such as high quality paper, synthetic paper or synthetic resin film. It is roughly classified into a coating type with a layer.

In the coating type, the amount of coating on one side is 1 to 10
g / ^{m 2} as low coating type, 10 to 20 g / ^{m 2} approximately intercoat Engineering type, there is a 20 g / ^{m 2} or more high coating types each inkjet printing sheet. In particular, in recent years, even in the low-coating type, the lower limit of one-side coating amount is 0.5 to 6 g.
/ M ² , which is close to that of plain paper, is preferable in terms of external appearance, writability with a pencil or the like, and handling, and this type of fine coating is desired. However, in the case of multi-color printing, not only single-color printing of yellow, magenta, cyan, and black, but also multi-color printing is performed by overlapping these colors. In the case of the type, the ink cannot be completely absorbed by the coating layer. As a countermeasure, there is a method in which a base paper having a relatively low size is used to absorb a part of the ink attached to the base paper itself as a support. However, in this case, the ink having a relatively low basis weight and a low size degree has a problem that the ink strikes through each other when printed on both sides, and the printed matter is not legible or the color balance is lost, resulting in an unsightly image. .

To solve these problems, Japanese Patent Publication No.
JP-A-26665 discloses an example of an ink jet recording paper in which a coating layer containing fine silica and a water-soluble polymer binder is provided on a base paper having a basis weight of 60 g / m ² and a Steckigt sizing degree of 4 seconds or less. And JP-A-59-3808.
No. 7 discloses that on a substrate having a sizing degree of 0 to 10 seconds,
An example of an ink jet recording material provided with an ink absorbing layer is disclosed, and JP-A-59-9516 discloses an example of an ink jet recording paper in which base paper having a Stigget size of 0 to 5 seconds is impregnated with polyvinylpyrrolidone or the like. Has been
Both are single-sided print records, and are not printable on both sides.

Further, as an ink jet recording sheet having a high ink absorbency and a good recording dot shape,
There is JP-A-60-63191. This publication is characterized in that the surface layer of a recording material (inkjet recording sheet) is a mixture of a filler and a fibrous material. Here, it is described that the material has a substrate made of a fibrous material and filler particles adhered to the surface of the substrate so as to be scattered very thinly. However, this publication does not mention the state where the filler and the fibrous material of the surface layer are mixed and the fibrous material forming the base material is exposed on the surface layer.

[0008] Contrary to the publication, the ink absorbability is excellent,
As a fine coating type ink jet recording sheet that has high image density and sharpness and can obtain print dots close to perfect circle,
JP-A-7-25132, wherein the recording surface of the recording sheet is coated with a composition mainly composed of an ultrafine inorganic pigment along the surface of a pulp fiber in a state of being entangled with the base paper surface. Forming a base material, wherein the shape of the pulp fiber coated on the recording surface can be visually recognized by a scanning electron microscope, and the surface coverage of the pulp fiber on the recording surface is 70% or more. Although the state where the fibrous material is exposed on the surface layer is mentioned, the basis weight of the base paper is 8 in order to absorb the excess ink with the pulp fiber as the support.
At 5 g / m ² , the degree of Stekigt is as low as 27 seconds,
Print dots with high image density and close to a perfect circle can be obtained, but partial penetration of ink can be suppressed because the surface coating of the pulp fiber on the recording surface is not almost completely covered. And ink strike-through occurs and double-sided printing is not possible.

[0009]

As described above, when the ink receiving layer has a low coating amount, a part of the adhered ink is absorbed by the support itself using a base paper having a relatively low size. In addition, the uniformity of sizing in a minute area is different depending on the sizing agent. In addition, the ink receiving layer applied on the support is not uniformly coated on the surface of the ink receiving layer with the entangled irregularities of the pulp fibers, so that the pulp fibers are extremely exposed. For this reason, the adhered ink penetrated into the support, that is, the base paper, along the exposed pulp fiber without forming print dots of a desired shape on the surface of the ink receiving layer, and the print dots spread and spread. It will take on a shape. In other words, the printed image lacks sharpness. Further, those having a basis weight of less than 100 g / m ² and a low degree of size cause ink strike-through due to a large amount of adhered ink and cannot withstand double-sided printing.

[0010] An object of the present invention is to provide a finely coated type ink jet printing sheet which is excellent in ink absorptivity without ink blurring.
An object of the present invention is to provide an ink-jet printing sheet which has high density and sharpness of a printed image, has little deformation of print dots, and can perform double-sided printing.

[0011]

The inventors of the present invention have studied to solve the above problems, and as a result, have found that the bleeding of the ink is small, the ink absorption is excellent, the density of the printed image is high, and the printing dot is high. We have invented an ink-jet printing sheet that can be printed on both sides of a fine coating type with little deformation.
That is, the ink jet printing sheet according to the present invention is an ink jet printing sheet having a printing surface on a base paper, wherein the base paper is talc and / or calcium carbonate as a filler, and ASA (alkenyl succinic anhydride) as an internal sizing agent. Neutral paper containing a reactive neutral sizing agent, and the product weight after coating on the base paper is 100 to 250 g /
m ^2, and nice person sizing degree of the product is 130-1
90 seconds, the printing surface of the printing sheet is surface-coated with a fine-particle inorganic pigment of a composition mainly composed of alumina along the surface of the pulp fiber in the entangled state of the base paper surface, and the surface-coated pulp fiber The shape can be visually recognized by a scanning electron microscope, and the form of the surface coating of the pulp fiber is almost completely covered with the surface.

The double-sided ink jet printing sheet of the present invention will be described in detail below. In the ink jet printing sheet of the present invention, the base paper is neutral paper containing talc and / or calcium carbonate as a filler and ASA (alkenyl succinic anhydride) reactive neutral sizing agent as an internal sizing agent. There is a feature. As a reason for specifying the filler, although the oil absorption is lower than various silicas, titanium dioxide, barium sulfate,
This is because it is higher than zinc oxide, is equal to or more than clay, and can appropriately absorb the alcohol-based organic solvent contained in the ink. However, silica absorbs ink so strongly that it also absorbs ink to be fixed on the surface coating, resulting in a low image density. Calcium carbonate is most suitable because it can simultaneously obtain high whiteness and high opacity in addition to an appropriate oil absorption. Further, talc is preferable because it has an appropriate oil absorption degree, and its flat shape improves smoothness and paper formation, and is improved so that it can uniformly absorb ink as a support. Next, the reason for specifying the internal sizing agent is that the size developing mechanism of the reactive sizing agent such as ASA in neutral papermaking is based on the fact that the sizing emulsion particles added to the pulp suspension are sufficiently dispersed and the pulp fiber It is based on the fact that it is isolated and fixed thereon, forms an ester bond with the cellulose hydroxyl group in the pulp in the drying step, and can exert more hydrophobicity than the rosin-based sizing agent.

The product weighed after double-sided coating of base paper is 100 to 2
At 50 g / m ² , the Stöckigt sizing degree of the product is 130-
By setting the time to 190 seconds, the amount of ink absorbed by the base paper portion becomes smaller than that of the rosin-based sizing agent, and no strike-through of ink occurs. In this case, the basis weight of the base paper is approximately 95 to 24.
At 5 g / m ² , it can be achieved by setting the Steigcht sizing degree to 100 to 150 seconds. Further, in the form of pulp fibers coated with a fine particle inorganic pigment of a composition mainly composed of alumina,
In addition, by forming a fine coating layer in which the form of the surface coating is almost completely covered with the surface, excellent quality of ink absorption, high image density and sharpness, and little print dot deformation can be obtained. Thus, two-sided printing becomes possible. When the basis weight of the base paper is 245 g / m ² or more,
Although a similar effect can be obtained with a material of about 150 seconds, the thickness of the paper increases, and the handling property and the economic efficiency are inferior.

On the other hand, a neutral rosin sizing agent generally used in neutral papermaking has a size expressing property in a very small area,
Although it shows uniformity at relatively low sizing degree and becomes a perfectly circular printed dot, the ink amount absorbed by the stencil part is small at low weighing with a basis weight of less than 95 g / m ² because of low sizing degree. More than is absorbed by the working layer, ink strike-through easily occurs.

The reactive neutral sizing agent such as ASA in the present invention is a cellulose-reactive sizing agent emulsified with various surfactants or water-soluble polymers used in a neutral region of pH 6 to 9. It is. Here, examples of the ASA type include a self-emulsifying type which can be easily emulsified with water, and a type containing a surfactant.

The ionicity of the reactive neutral sizing agent such as ASA can be selected from anionic and cationic depending on various surfactants or water-soluble polymers used at the time of emulsification. In the present invention, various conventionally used anionic, nonionic, cationic or amphoteric retention enhancers, polyethylene oxide, polyamide resin, hydrophilic cross-linked polymer particle dispersion or the like or derivatives or denatured products thereof And a colloidal silica, bentonite and other compounds are used in combination as appropriate.As a result, an ASA sizing agent and a cationic or amphoteric hydrophilic crosslinked polymer particle dispersion or the like or a derivative or denatured product thereof are produced. It is desirable to combine a yield enhancer or a yield system as one of the components.

In order to express the sizing properties of the ASA sizing agent, a polyvalent metal compound of aluminum (for example, sulfate band, polyaluminum silicate sulfate,
Needless to say, polyaluminum chloride, sodium aluminate, etc.) are blended.

Further, the ink jet printing sheet of the present invention is coated on the surface of the support, that is, the pulp fiber of the printing surface on the base paper surface to such an extent that the shape thereof can be sufficiently identified. The surface coating of the printing surface is uniformly covered with the fine particle inorganic pigment along the surface of the pulp fiber, and is thinly covered according to the shape of the pulp fiber surface. The form of the surface coating on the printing surface almost completely covers the surface of the pulp fiber on the printing surface, so that the characteristics intended by the present invention can be sufficiently exhibited. The reason is that when the printing surface is evenly coated, the ink spreads in the printing surface direction because the printing surface is evenly coated when the ink adheres to the printing surface using an inkjet printer. As a result, the surplus ink penetrates uniformly from the surface coating surface in the thickness direction of the base paper, so that partial ink permeation is suppressed, and no ink strikethrough occurs.

On the other hand, when the form of the surface covering the pulp fiber on the printing surface is almost completely uncovered,
The rate at which the ink spreads in the printing surface direction increases, and as a result, the penetration into the base paper becomes non-uniform, and the basis weight of the base paper is 95 to 245 g / m ² , and the degree of stoichito sizing is 100 to
Even at a portion as large as 150 seconds, penetration of the ink cannot be suppressed, and partial strikethrough of the ink appears.

On both sides of the ink jet printing sheet of the present invention, the surface coated surface is a surface uniformly covered along the pulp fiber of the base paper, and a composition mainly composed of alumina is used as a fine particle inorganic pigment. Cover. For a pulp fiber forming a base paper having a fiber diameter on the order of several tens of μm, the primary particle diameter of the fine-particle inorganic pigment is at most 1
μm, preferably 0.5 to 0.01 μm. The finer the particle size, the more uniform the surface coating on the pulp fiber, which is preferable.

With respect to the surface coating of the pulp fiber surface on the printing surface on both sides of the ink jet printing sheet of the present invention, as a means for evaluating the form of the surface coating, an image is taken with a scanning electron microscope, and the coverage is calculated based on the imaging. to decide.

The following can be exemplified as the fine particle inorganic pigment. For example, alumina or alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or its hydrate, pseudo-boehmite, etc.)
And the like, if the primary particles are porous, it is still more preferable, or even non-porous aggregates during preparation of the coating liquid,
It is preferred that the pulp fibers be further coagulated during coating and drying to form a porous surface coating surface on the pulp fiber surface. In particular, in the present invention, it is possible to coat the pulp fiber itself with a fine particle inorganic pigment having an average particle size that is 1/100 or less of the fiber width of each pulp fiber on the base paper surface. preferable.

Further, as the inorganic pigment which can be used in combination with the fine particle inorganic pigment, any conventionally known inorganic pigment 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, synthetic amorphous silica, aluminum hydroxide,
Examples include lithopone, zeolite, hydrohaloysite, and magnesium hydroxide. Among these inorganic pigments, porous inorganic pigments are preferable, and porous synthetic amorphous silica, porous magnesium carbonate, porous alumina, and the like can be mentioned. Particularly, porous synthetic amorphous silica having a large pore volume is preferable. . Organic pigments such as styrene-based plastic pigment, acrylic-based plastic pigment, polyethylene, microcapsules, urea resin, melamine resin, and nylon resin can also be used in combination with the above-mentioned fine particle inorganic pigment.

Further, as a water-soluble metal salt, aluminum sulfate, potassium aluminum sulfate (potassium alum), cesium aluminum sulfate, sodium aluminum sulfate, ammonium nitrate are used for fixing dyes.
These hydrates can also be used in combination with the fine particle inorganic pigment.

As the binder to be used together with the fine particle inorganic pigment for coating the surface, for example, polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soybean protein Conjugated diene-based copolymer latex such as maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; polymer or copolymer of acrylate and methacrylate Polymer latex such as polymer or copolymer of acrylic acid and methacrylic acid; vinyl polymer latex such as ethylene-vinyl acetate copolymer; or functional group-containing monomer such as carboxyl group of these various polymers. Functional group-modified polymer latex; thermosetting synthetic resin based binder such as melamine resin and urea resin; aqueous binder; polymethyl methacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, alkyd resin, etc. Synthetic resin binders of
At least one kind can be used. Further, as cationic resins to be added for fixing conventionally known dyes, primary to quaternary ammonium salt resins, dimethyldiallylammonium chloride / sulfur dioxide copolymer, dimethylamine / epichlorohydrin resin, polyamide epichlorohydride A phosphorus resin, acrylamide / diallylamine resin, polyvinylamine resin, dicyandiamide resin, and the like can be used in combination.

The total amount of the binder can be appropriately adjusted in accordance with the characteristics of the target ink jet printing sheet.
5 to 20% by weight. Furthermore, as other additives,
Pigment dispersants, thickeners, flow improvers, defoamers, foam inhibitors,
Release agents, foaming agents, penetrants, coloring dyes, coloring pigments, optical brighteners, ultraviolet absorbers, antioxidants, preservatives, anti-binders,
A water-proofing agent, a wet paper strength enhancer, a dry paper strength enhancer, and the like can be appropriately blended.

In the present invention, the method of coating the surface includes coating or impregnation. However, if the form of the surface coating is almost completely covered with the surface, the amount of coating on the surface coated surface can be reduced. However, there is no particular limitation. Usually, when the paper is oriented like plain paper, the dry coating amount is 0.5
-3 g / m ² is preferable, but 1-3 g / m ² is particularly preferable in view of the state of the surface coating almost completely covered with the surface, fixing of ink, water resistance, and dot shape.

The pulp for base paper according to the present invention is LBK.
Chemical pulp such as P, NBKP, GP, PGW, RMP,
Mechanical pulp such as TMP, CTMP, CMP, CGP, D
Wood pulp such as waste paper pulp such as IP can be used,
Particularly, chlorine-free bleached pulp is preferable from an environmental viewpoint. The filler must contain talc and / or calcium carbonate, but can be used in combination with a conventionally known pigment. Further, in the paper stock, together with the internal sizing agent as described above and a polyvalent metal compound of aluminum, a binder and / or a fixing agent, a retention improver cationizing agent, paper as long as the desired effects of the present invention are not impaired. Various additives such as a force enhancer can be used as needed. These raw materials are mixed and manufactured by various apparatuses such as a fourdrinier paper machine, a round paper machine, and a twin wire paper machine.In the present invention, base paper subjected to size press treatment only with hot water, , Starch, polyvinyl alcohol, etc., both singly or in combination, and size-pressed base paper. The surface coating may be directly applied to such base paper, or a calendar device such as a machine calendar, a heating calendar, or a soft calendar may be used for the purpose of controlling smoothness.

When the surface is coated, coating and impregnating methods include various blade coaters, roll coaters, air knife coaters, bar coaters, rod coaters, gate roll coaters, curtain coaters, short dwell coaters, and the like.
Various devices such as a gravure coater, a flexographic gravure coater, and a size press can be used on-machine or off-machine. However, in the present invention, the air knife coater is particularly preferable in that the contour coating is performed, a constant coating film thickness is obtained, and the form of the surface coating is almost completely coated. Further, after coating or impregnation, finishing may be performed using a calendar such as a machine calendar, a heating calendar, a super calendar, and a soft calendar.

The aqueous ink referred to in the present invention is a printing recording liquid comprising the following colorant, liquid medium, and other additives. Coloring agents include direct dyes, acid dyes, basic dyes, reactive dyes, and soluble dyes such as food dyes.

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, C1-C4 alkyl alcohols 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; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2, 6-hexanetriol, thiodiglycol, hexylene glycol,
Alkylene glycols having 2 to 6 alkylene groups such as diethylene glycol; lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol and monomethyl ether; . 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. Examples of the other additives include a pH adjuster, a metal sequestering agent, a fungicide, a viscosity adjuster, a surface tension adjuster, a wetting agent, a surfactant, and a rust preventive.

The ink-jet printing sheet of the present invention is not limited to use as an ink-jet printing sheet, but may be used as any printing sheet using a liquid ink at the time of printing. For example, a heat-fusible substance, a heat-fusible ink containing a dye or pigment as a main component is coated on a thin support such as a resin film, high-density paper, or synthetic paper. Sheet for thermal transfer printing, which melts and transfers ink, sheet for inkjet printing, which heats and melts heat-meltable ink to form fine droplets, and performs flying printing, sheet for ink-jet printing using ink in which an oil-soluble dye is dissolved in a solvent And an image receiving sheet corresponding to a photosensitive pressure-sensitive donor sheet using microcapsules containing a photopolymerizable monomer and a colorless or colored dye / pigment.

A common feature of these printing sheets is that the ink is in a liquid state during printing. The liquid ink penetrates or spreads in the depth direction or the horizontal direction of the ink receiving layer of the printing sheet before being cured, solidified or fixed. The above-described various printing sheets require absorptivity according to each system, and there is no limitation even if the inkjet printing sheet of the present invention is used as the above-described various printing sheets. Further, the ink jet printing sheet of the present invention may be used as a printing sheet for heating and fixing an electrophotographic recording toner widely used in copiers and printers.

[0034]

The ink jet printing sheet of the present invention is a finely coated type ink jet printing sheet, and the printing surface on both sides of the printing sheet contains an ASA-reactive neutral sizing agent as an internal sizing agent. The surface of the pulp fiber is coated along the pulp fiber in the entangled state of the functional paper, and the shape of the pulp fiber coated on the printing surface can be visually observed with a scanning electron microscope, and the surface of the pulp fiber surface on the printing surface It is characterized in that the form of the coating is almost completely covered with the surface, and there is no ink bleeding unevenness and excellent ink absorbability. This is because when the ink is applied to the printing surface of both sides of the printing sheet, it does not spread in the printing surface direction, penetrates uniformly to the surface coating surface, and the excess ink is the thickness of the neutral paper containing the ASA sizing agent. Penetrates uniformly in the direction, and suppresses further ink permeation in a high-size portion where the basis weight of the product after both-side coating is 100 to 250 g / m ² and the product's Steckigt sizing degree is 130 to 190 seconds; As a result, it is possible to obtain an ink jet printing sheet in which partial strike-through of ink does not occur and in which the density and sharpness of a printed image are high.

[0035]

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. In addition, the fine particle inorganic pigment was used as an aqueous dispersion containing polyvinyl alcohol, and all were represented by solid contents.

Example 1 [Preparation of base paper] LBKP10 having a freeness of 450 mlcsf
10. A heavy calcium carbonate (Sunlight 700, manufactured by Takehara Chemical Industries) as a filler in a pulp slurry consisting of 0 parts
7 parts, talc (CS-12, manufactured by Fuji Talc) 2.3
Part, cationic starch (Cato304, manufactured by NSC Japan)
0.85 part, sulfuric acid band 1.0 part, ASA-reactive neutral sizing agent (Colopearl Z-1100, manufactured by Hoshiko Chemical Co., Ltd.)
Add 1 part internally and use a size press to oxidize starch (MS # 3)
8.0, manufactured by Nippon Shokuhin Kako) 7.0 parts, fibrin reactive surface sizing agent (Harcon SS-362, manufactured by Nippon PMC)
03 parts were externally added, formed and dried with a fourdrinier paper machine, and machine calendered to prepare a base paper having a basis weight of 120 g / m ² . In addition, the Stekihito sizing degree of the prepared base paper is
113 seconds.

[Preparation of Ink-Jet Printing Sheet] On the base paper prepared as described above, a mixed solution of alumina and polyvinyl alcohol (solid weight ratio: alumina / polyvinyl alcohol = 1) as a fine particle inorganic pigment of the composition of the surface-coated surface was used.
00/15) 46.5 parts, potassium alum 10.7 parts, aluminum nitrate 10.7 parts as fixing agent for dye,
A solid content concentration of 9.4% containing 32.1 parts of a cationic quaternary ammonium salt resin as a main component as an ink water-resistant fixing agent.
The aqueous dispersion was prepared, and was simultaneously coated on both sides with an air knife coater so as to have a dry solid content of 2 g / m ² on one side, and dried to prepare an inkjet printing sheet.
The prepared sheet had a Steckigt sizing degree of 15
It was 0 seconds.

Example 2 On the base paper prepared in Example 1, an alumina mixed solution containing polyvinyl alcohol as a fine particle inorganic pigment (solid weight ratio: alumina / polyvinyl alcohol = 100/15)
7 parts, 60.4 parts of a cationic quaternary ammonium salt resin as a water-resistant fixing agent for ink, and 9.9 parts of the same dimethyldiallylammonium chloride-sulfur dioxide copolymer having a solid content of 9.9%. An aqueous dispersion was prepared, and the dry solid content on one side was 2 g / m ² using an air knife coater.
Were simultaneously coated on both sides and dried to produce a sheet for inkjet printing. Note that the prepared sheet had a Steckigt sizing degree of 165 seconds.

Comparative Example 1 [Preparation of base paper] LBKP10 having a freeness of 450 mlcsf
10. A heavy calcium carbonate (Sunlight 700, manufactured by Takehara Chemical Industries) as a filler in a pulp slurry consisting of 0 parts
7 parts, talc (CS-2, manufactured by Fuji Yu Luc Co.) 2.3
Part, cationic starch (Cato304, manufactured by NSC Japan)
0.85 part, sulfuric acid band 1.0 part, neutral rosin sizing agent 0.5 part (size pine NT-85, manufactured by Arakawa Chemical Industries)
Was internally added, warm water was externally added by a size press, paper-dried by a fourdrinier paper machine, machine-finished, and a base paper having a basis weight of 120 g / m ² was produced. Note that the prepared paper had a Stöckicht sizing degree of 24 seconds.

[Preparation of Ink-Jet Printing Sheet] The base paper prepared as described above was used as a composition for a surface-coated surface.
Alumina mixed solution containing polyvinyl alcohol (solid weight ratio: alumina / polyvinyl alcohol = 100/15)
46.5 parts, potassium alum 1 using dye as fixing agent
0.7 parts, aluminum nitrate 10.7 parts, cationic quaternary ammonium salt resin 3 as ink water-resistant fixing agent
An aqueous dispersion having a solids concentration of 9.4% containing 2.1 parts as a main component was prepared, and simultaneously coated on both sides using an air knife coater so as to have a dry solids content of 2 g / m ² on one side. It dried and the sheet for inkjet printing was produced. The prepared sheet had a Steckigt sizing degree of 29 seconds.

COMPARATIVE EXAMPLE 2 The base paper of Comparative Example 1 was the same except that the basis weight was 85 g / m ² , and the prepared base paper was the same except that the Stockigt sizing degree was 20 seconds. At a time of 0.5 g / m ² to obtain a sheet for inkjet printing. The prepared sheet had a Steckigt sizing degree of 24 seconds.

COMPARATIVE EXAMPLE 3 An air knife coater was used except that the base paper of Example 1 had a basis weight of 85 g / m ² , and the external paper was changed to warm water to produce a base paper having a Stechig sizing degree of 25 seconds. Was applied simultaneously to both sides so that the dry solid content on one side was 2.0 g / m ^2, and dried to prepare a sheet for inkjet printing. In addition, the Steckhito sizing degree of the produced sheet is as follows.
31 seconds.

Comparative Example 4 An air knife coater was used except that the base paper of Example 1 had a basis weight of 85 g / m ² , and the external paper was changed to warm water to produce a base paper having a Stechig sizing degree of 25 seconds. Was applied simultaneously on both sides so that the dry solid content on one side was 5.0 g / m ^2, and dried to prepare a sheet for inkjet printing. In addition, the Steckhito sizing degree of the produced sheet is as follows.
35 seconds.

Comparative Example 5 [Preparation of base paper] LBKP10 having a freeness of 450 mlcsf
10. A heavy calcium carbonate (Sunlight 700, manufactured by Takehara Chemical Industries) as a filler in a pulp slurry consisting of 0 parts.
7 parts, talc (CS-2, manufactured by Fuji Yu Luc Co.) 2.3
Part, cationic starch (Cato304, manufactured by NSC Japan)
0.85 part, sulfuric acid band 1.0 part, ASA-reactive neutral sizing agent (Colopearl Z-1100, manufactured by Hoshiko Chemical Co., Ltd.)
Add 1 part internally and use a size press to oxidize starch (MS # 3)
8.0, manufactured by Nippon Shokuhin Kako) 7.0 parts, fibrin reactive surface sizing agent (Harcon SS-362, manufactured by Nippon PMC)
One part was externally added, formed and dried with a fourdrinier paper machine, and machine calendered to prepare a base paper having a basis weight of 120 g / m ² . Note that the prepared paper had a Stechigt sizing degree of 1
70 seconds.

[Preparation of Ink-Jet Printing Sheet] The base paper prepared as described above was used as a composition for the surface-coated surface.
Alumina mixture containing polyvinyl alcohol (solid weight ratio: alumina / polyvinyl alcohol = 100/15)
46.5 parts, potassium alum 1 as fixing agent for dye
0.7 parts, aluminum nitrate 10.7 parts, cationic quaternary ammonium salt resin 3 as ink water-resistant fixing agent
An aqueous dispersion having a solids concentration of 9.4% containing 2.1 parts as a main component was prepared, and simultaneously coated on both sides using an air knife coater so as to have a dry solids content of 2 g / m ² on one side. It dried and the sheet for inkjet printing was produced. The prepared sheet had a Steckigt sizing degree of 222 seconds.

Comparative Example 6 [Preparation of base paper] LBKP10 having a freeness of 450 mlcsf
10. A heavy calcium carbonate (Sunlight 700, manufactured by Takehara Chemical Industries) as a filler in a pulp slurry consisting of 0 parts
7 parts, talc <CS-2, manufactured by Fuji Yu Luc Co.> 2.3
Part, cationic starch (Cato304, manufactured by NSC Japan)
0.85 part, sulfuric acid band 1.0 part, ASA-reactive neutral sizing agent (Colopearl Z-1100, manufactured by Hoshiko Chemical Co., Ltd.)
Add 1 part internally and use a size press to oxidize starch (MS # 3)
7.0, Nippon Shokuhin Kako Co., Ltd., 7.0 parts, fibrin reaction type surface sizing agent (Harcon SS-362, manufactured by Nippon PMC)
01 parts were externally added, formed and dried by a fourdrinier paper machine, and machine calendered to prepare a base paper having a basis weight of 120 g / m ² . In addition, the Stekihito sizing degree of the prepared base paper is
Except for 92 seconds, it was the same as Comparative Example 5, and was simultaneously coated on both sides using an air knife coater so that the dry solid content on one side was 2.0 g / m ^2, and dried to form an inkjet printing sheet. Produced. The prepared sheet had a Steckigt sizing degree of 138 seconds.

With respect to the ink jet printing sheets prepared in Examples 1 and 2 and Comparative Examples 1 to 6, the printing model was set to PM-1750C manufactured by Epson Corporation, and evaluated based on the following method. It was shown to.

The image density was measured using a reflection densitometer (DM-1400: manufactured by Dainippon Screen Mfg. Co., Ltd.) at the portion printed in black with black ink. Normally, 1.30 or more is good, and ◎ indicates good, ○ indicates a level having no practical problem, Δ indicates a level having practical problem, and × indicates poor.

The color development was evaluated comprehensively after printing by comparing the color development and boundary bleeding of solid portions of cyan, magenta, yellow and black with visual perception. ◎ indicates high density and vivid and has no boundary bleeding, は indicates a level having no practical problem, Δ indicates a level having a practical problem, x indicates low density, lacks vividness, and indicates poor boundary blurring.

The water resistance was determined by dipping in running water for 5 minutes after printing and comparatively evaluating the remaining degree of the ink. ◎ indicates that the ink almost completely remains and is good, ○ indicates a level having no practical problem,
Δ indicates a level at which there is a problem in practical use, and X indicates that the ink almost leaked out and was defective.

After printing on one side, strike-through of the ink on the back side of the strike-through was evaluated by visual perception. ◎ indicates that the ink was completely fixed in the paper layer and did not penetrate, and was good. ○ indicates a level with no practical problem, Δ indicates a level with practical problem, and x indicates that the ink partially penetrated completely. And indicate failure.

After printing, the feathering of fine lines was compared and evaluated by visual feeling after printing. ◎ indicates no bleeding, good, ○ indicates a level having no practical problem, △ indicates a level having a practical problem, x indicates ink bleeding, thick fine lines, and poor.

The dot shape was obtained by optically enlarging the printed dot, and the shape was compared and evaluated visually. ◎ indicates that the ink dots are completely circular and is good, は indicates that the circles are slightly distorted, but there is no practical problem, △ indicates that the circles are distorted and there is a practical problem, and × indicates that the ink dots are Partially blurred, lost in a circular shape, indicating a defect.

The surface of the printing surface is coated by scanning an X-ray image of the metal element of the material used on the pulp fiber surface of the ink jet printing sheet with a scanning electron microscope, and visually inspecting the pulp fiber by the imaging. The morphology of the surface coating on the surface was evaluated. ◎ indicates that the surface is almost completely covered,
Good, は indicates a level at which a part of the surface is not partially covered is about 10 to 20%, and Δ indicates a part which is not coated at the surface is 3 to 5%.
A level that is relatively high, × indicates that the part not covered with the surface is 6
Defects are shown at a certain level or higher.

[0055]

[Table 1]

From the results shown in Table 1, the ink jet printing sheets of Examples 1 and 2 and Comparative Examples 1 to 6 show that the printing sheets of Examples 1 and 2 have a small particle diameter of the fine inorganic pigment used. The form of the surface coating was within the scope of the present invention, and both were good in both ink color development and image density. Further, the shape of the dot was almost circular. On the other hand, in Comparative Example 1, the form of the surface coating was within the scope of the present invention because the internal sizing agent used was different, but the base paper and the degree of Stekigt sizing after coating were as low as 20 seconds, and only Was inferior and poor. In Comparative Example 2, the internal sizing agent used was the same as in Comparative Example 1. However, since the coating amount was as small as 0.5 g / m ² , the form of the surface coating was low, the shape of the dots was inferior due to distortion, and Human size degree 2
It was as low as 0 seconds, poor in strikethrough, and poor. Furthermore,
In Comparative Example 3, warm water was used as an external additive when the base paper was made in Example 1, and the Steckigt sizing degree was as low as 20 to 30 seconds, and the strike-through property was poor and poor. Comparative Example 4
Increased the coating amount of Comparative Example 3 from 2 g / m ² to 5 g / m ² , but the absolute amount of polyvinyl alcohol as the binder was insufficient, the fixing power of the fine particle inorganic pigment was poor, and as a result, the water resistance was poor, It was bad. In Comparative Example 5, the external paper sizing property of the base paper was enhanced, and the Stockecht sizing degree of the base paper was increased to 170 seconds, and the strike-through of the ink was good, but there was a practical problem due to bleeding and dot shape. Level. In Comparative Example 6, the base paper had a Stighit sizing degree on the order of 90 seconds, and the results were inferior in strikethrough, bleeding, and dot shape. From the above, the Stekigt sizing degree of the base paper was 100 to 150 in a state where the form of the surface coating was almost completely covered with the surface.
Seconds, the printing ability was 130 to 190 seconds after coating, indicating that the printability was balanced.

[0057]

The ink jet printing sheet of the present invention is prepared on neutral paper containing talc and / or calcium carbonate as a filler and ASA (alkenyl succinic anhydride) reactive neutral sizing agent as an internal sizing agent. The surface of the pulp fiber on the base paper surface is almost completely covered with the fine particle inorganic pigment of the composition mainly composed of alumina, and the product basis weight after double-sided coating is 100 to 250 g / m ² , and the Steckigt sizing degree of the product is By having a printing surface of 130 to 190 seconds, the pulp fiber shape coated on the printing surface can be visually recognized with an electronic head microscope, and the form of the surface coating is almost completely covered with the ink. There is no strike-through, no ink bleeding unevenness, excellent ink absorbency, high image density and sharpness, and a double-sided printable product with little print dot deformation.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Koichi Kaneko 3-5-1 Nishi-Zao, Nagaoka-shi, Niigata Pref. Inside the Research Laboratory of Hokuetsu Paper Mills (72) Inventor Toru Minagawa 3-5, Nishi-zao, Nagaoka-shi, Niigata (1) Inside the Research Laboratory of Hokuetsu Paper Mills Co., Ltd. 4-8-13 Shinjuku, Shinjuku, Zushi City, Kanagawa Prefecture F-term (reference) 2H086 BA15 BA21 BA24 BA32 BA33 BA37 BA41 BA42 BA45 4L055 AG10 AG17 AG26 AG41 AH01 AH02 AH10 BE08 EA08 EA10 GA09 GA34

Claims (3)

[Claims] 1. An ink jet printing sheet having printing surfaces on both sides of a base paper, wherein the base paper is a neutral paper containing a filler and a neutral internal sizing agent, and the product after being coated on the base paper The basis weight is 100 to 250 g / m ² , the degree of Stekigt sizing of the product is 130 to 190 seconds, and the printing surface of the printing sheet is made of alumina along the surface of the pulp fiber in a state of being entangled with the base paper surface. The surface is coated with a fine particle inorganic pigment of a composition mainly composed of, and the shape of the surface-coated pulp fiber can be visually recognized by a scanning electron microscope,
A finely coated ink jet printing sheet capable of printing on both sides, characterized in that the surface of the pulp fiber is almost completely covered. 2. The ink jet printing sheet according to claim 1, wherein the base paper contains an ASA (alkenyl succinic anhydride) reactive neutral sizing agent as an internal sizing agent. Sheet. 3. The ink-jet printing sheet according to claim 1, wherein the base paper contains talc and / or calcium carbonate as a filler.