JPH0725191B2 - Inkjet recording sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a recording sheet for an inkjet printer.

[Prior Art] In recent years, the demand for color printers has been expanding. In particular, inkjet recording, which is a type of non-impact recording method, has been highly evaluated because color recording can be performed at relatively high speed with a simple device. However, many points still have to be overcome in order to obtain multicolor, high-speed and high-definition images in inkjet recording.

When viewed from the side of the recording sheet, it has sufficient ink absorbency and ink dryness. In particular, in order to record in multiple colors, of course, multiple ink dots are overlaid,
Alternatively, since it is necessary to cope with an increase in the number of ink dots per unit area, the ink absorption capacity of the recording layer is sufficiently large, and drying after ink fixing is fast for high speed recording.

Inkjet paper is either a cellulose fiber itself or a plain type that absorbs ink into the voids formed between fibers or fillers and fibers, and fine voids in the coating layer that coats the paper surface that is the support with fillers and binders. It is roughly divided into coat types that absorb ink. Although the coated type has a small spread of ink dots and a shape close to a circle and is excellent in resolution, it has a small ink absorption capacity and a slow ink absorption speed, which makes it unsuitable for multicolor recording with a large amount of ink and high in cost. There are drawbacks.

Therefore, recently, along with the speeding up of printers, there is a growing need for plain type paper which is economical in terms of consumables and has excellent texture and feel like paper.

Plain-type paper technology is shown in three main directions. One direction is, for example, JP-A-53-49113.
And JP-A-58-8685. The former is a sheet filled with urea formalin resin powder and coated with a water-soluble polymer, and the latter is coated and impregnated with a synthetic silicate and glass fiber-filled sheet with a water-soluble polymer. It was done. A characteristic of these ink jet recording sheets is that the specific fine powder is internally added to an unsized base paper to improve the ink absorbency and to cope with high speed printing. This type of recording sheet is, so to speak, only an ink receiving layer,
When multicolor recording with a large amount of ink is carried out on this sheet, the ink spreads in the lateral direction of the paper and the ink dots become large and become large, resulting in poor resolution. Further, since it penetrates deeply in the thickness direction, it causes a decrease in recording density due to scattering of light by the upper layer portion of the recording sheet, and there is a big problem that strike-through, that is, see-through of a printing portion and seepage of ink occurs.

The other direction is Japanese Patent Publication No. 60-27588 and Japanese Patent Publication No. 61-50795.
As disclosed in Japanese Patent Laid-Open Publication No. JP-A-2003-264, it is intended to control the dot diameter by giving a fine size to the sheet and suppressing the ink absorbability to some extent. The former is a sheet in which a wet paper strength enhancer is internally applied and a small amount of surface coating is applied so as not to cover the paper surface, and the Steckigt sizing degree is 3 seconds or less. The latter is a saponified petroleum resin. It is an inkjet recording recording sheet in which a paper sizing agent is applied to the surface of paper. Due to the effect of the sizing agent, these recording sheets can suppress the strike-through and the lateral spreading of ink dots among the drawbacks of the above-mentioned technology, but they are not suitable for multicolor recording because of their poor ink absorption. There are some drawbacks.

Another technology of the plane type is JP 63-
No. 118287 proposes a two-layer paper for inkjet recording. The basic idea of this disclosed technique is that the first layer is an uncoated paper in which the support sheet is composed mainly of pulp fibers and the second layer is provided with a layer composed of a filler and pulp fibers for improving the recording density. However, as described above, in the color recording of the water-based ink having a large amount of ink, the penetration of the ink into the untreated first layer is severe, which is an important issue in the inkjet recording of non-coated paper. However, the strike-through of the ink has not been improved by this method.

[Problems to be Solved by the Invention] The present invention has a uniform image quality, high recording density, and sufficient ink absorbability suitable for multicolor recording while maintaining the texture and feel of uncoated paper. In addition, it is intended to provide an inkjet recording paper with less strike-through.

[Means for Solving the Problems] As a result of repeated studies to solve the above-mentioned problems, an ink receiving layer (A layer) and a base layer (B layer) composed of one or more layers are prepared. A combined inkjet recording sheet, wherein an ink permeation-preventing agent is applied to the surface of layer B that is not adjacent to layer A, or the layer B further contains a sizing agent and / or a cationic polymer. By doing so, the above problems were solved and the present invention was completed.

A typical structure of the inkjet recording sheet of the present invention is shown in FIGS. In the figure, A is an ink receiving layer, and B
Is a base layer, 2 is a treatment agent containing layer, 3 is an ink permeation preventive layer, 4 is a fine coating layer for the purpose of improving image quality, and is a part of the ink receiving layer, and 1 is the inkjet of the present invention. It is a recording sheet.

FIG. 1 shows an ink jet recording sheet 1 in which the ink receiving layer A and the base layer B are combined and an ink permeation preventive agent is applied from the back surface of the base layer B to form the ink permeation preventive layer 3. Here, the ink permeation preventive agent permeates the base layer B to some extent and the base layer B partially or entirely functions as the ink permeation preventive layer, and the ink permeation preventive agent hardly permeates into the base layer B and the ink permeation preventive layer 3. Invasion of ink may be prevented near the interface with the base layer B.

In FIG. 2, after the ink receiving layer A and the base layer B containing the sizing agent and / or the cationic polymer to form the treatment agent-containing layer 2 are combined, the base layer B (treatment agent-containing layer 2 2) is applied to the back surface of the recording medium 1 to form the recording sheet 1. The purpose of the sizing agent and the cationic polymer here is firstly to appropriately control the ink permeation from the ink receiving layer surface during ink jet recording. Secondly, the ink permeation inhibitor applied after the formation of the multilayer paper. Does not penetrate deeply into the ink-receiving layer A through the base layer B, especially when it contains a cationic polymer, it captures the dye of the ink penetrating through the ink-receiving layer, while the applied ink It is intended to combine with a penetration preventive agent (anionic paint) to form an ink penetration preventing interface to improve ink back-through.

In the present invention, in order to combine the ink receiving layer and the base layer, prepare a paper material for the ink receiving layer and the base layer, respectively, for example, a paper machine such as a cylinder type bat type, suction former, ultraformer, or long paper. Net type (On-Top-Twin
-Former) Arcu-Former (Tampella AB: OY), Ultr
a-Twin-Former (manufactured by Kobayashi Manufacturing Co., Ltd.), Alladin-Fo
It is performed by a paper machine such as rmer (manufactured by Sanki Tekko Co., Ltd.).
The present invention is a recording sheet in which an ink permeation preventive agent is applied to the back surface of the base layer after forming a multi-layered sheet obtained by combining the ink receiving layer and the base layer using these paper machines. It is shown that the inclusion of the sizing agent and / or the cationic polymer in the composition makes it possible to obtain an extremely excellent ink jet recording sheet having no ink strikethrough.

The first role of the base layer B and the ink permeation prevention layer 3 is to suppress the see-through (show-through) of the ink that is seen through from the back surface when ink jet recording is performed on the recording sheet. The second role is to prevent ink from penetrating so that ink does not penetrate through the paper layer and reach the back surface (strike through). That is, the main function is to prevent the ink that has penetrated the ink receiving layer A and reached the base layer B from penetrating further deeply and rapidly into the base layer. Therefore, the opacity and sizing degree are important properties that the base layer should have, and the opacity measured by JIS P8138 is 75% or more, and the Steckigt sizing degree of the base layer (basis weight 60 g / m ² ) measured by JIS P8122. Is preferably 3 seconds or more. When the opacity is 75% or more, the ink that has passed through the ink receiving layer and reaches the base layer has less show-through that can be visually recognized from the back surface (show-through), and thus the strike-through is reduced. When the Steckigt sizing degree is 3 seconds or more, penetration of ink into the base layer (strike through) can be suppressed in the base layer, and as a result, strikethrough can be improved. In particular, the effect is remarkable when the ink penetration inhibitor applied from the back surface of the base layer contains a sizing agent. However, it is preferable to excessively increase the size of the base layer because, in the case of a printer having a large amount of ink and the ink receiving layer cannot accommodate the ink due to the type of printer, the ink may flow out. Absent. If the sizing degree is too low, the ink penetrates deep into the base layer and strikethrough becomes noticeable, and the amount of ink remaining in the ink receiving layer decreases, resulting in a decrease in recording density and a decrease in image sharpness. Not preferable. Therefore, it is preferable that the size is 3 seconds or more, which is a so-called fine size, and usually about 3 to 50 seconds.

In the base layer B of the present invention, since the ink permeation preventive agent is applied from the back surface side of the base layer B, a so-called general internally added sizing agent is not necessarily required. However, in the present invention, as shown in FIG. 2, in order to appropriately control the ink permeation during recording, or to prevent the migration of the ink permeation inhibitor to the ink receiving layer A, a small amount of sizing agent and / or
Alternatively, it is preferable that a cationic polymer is contained in the base layer B, the layers A and B are combined, and then the ink permeation inhibitor is applied from the back surface of the base layer B. The sizing agents listed here are reinforced rosin sizing agents, petroleum resin-based sizing agents, emulsion rosin sizing agents, alkenylsuccinic acid type synthetic sizing agents, and alkyl ketene dimer for neutral papermaking used for re-papermaking. In addition to reactive sizing agents such as alkenyl succinic anhydride and general sizing agents such as self-fixing cationic resin sizing agents, cationic polymers can also be used. The amount of the sizing agent added is preferably a trace amount, and the pulp fiber of the base layer 10
It is desirable to add 0.01 part to 2.5 parts to 0 parts, the cationic polymer is 0.0 parts to 100 parts of valve fiber.
It is desirable to add 1 part to 5 parts. As the cationic polymer, polyethyleneimine, polydimethyldiallylammonium chloride, polyalkylenepolyamine dicyandiamide ammonium condensate, polyvinylpyridinium halide, alkyl (meth) acrylate 4
Quaternary ammonium salt, (meth) acrylamidoalkyl 4
Examples thereof include primary ammonium salt, ω-chloro-poly (oxyethylene-polymethylene-alkyl quaternary ammonium salt), and polyvinylbenzyltrimethylammonium salt.

Among these, a cationic sizing agent and a cationic polymer are preferable, and in this case, it is preferable to use an anionic sizing agent or an anionic coating as an ink permeation preventive agent applied after forming the multilayer paper of the present invention. These cationic sizing agents and cationic polymers function as ink supplements, and when combined with anionic paints, the cationic polymers and anionic paints react and become insoluble in the base layer, so ink It becomes the permeation prevention interface. These characteristics of the recording sheet improve the ink absorbability of a printer having a large amount of ink and have an excellent effect in terms of strike-through of ink.

As the ink permeation preventive agent of the present invention, in addition to so-called surface sizing agents for general paper, materials and paints having a low affinity for water-based inks or having a hydrophobic property that inhibits the permeation of water-based inks are used. it can.

As the surface sizing agent, a reinforced rosin sizing agent used for acidic papermaking, a petroleum resin-based sizing agent, an emulsion type rosin sizing agent, an alkenylsuccinic acid type synthetic sizing agent, and an alkyl ketene dimer for neutral papermaking,
Examples include reactive sizing agents such as alkenyl succinic anhydride, self-fixing cationic resin sizing agents, anionic or cationic acrylamides, and wax emulsions and silicones. These are starch and polyvinyl. A water-soluble resin such as alcohol can also be added and applied. In the case of this paint, in order to prevent it from penetrating too deeply into the base sheet and impeding the penetration of the ink from the ink receiving layer during ink jet recording, the viscosity of the paint is preferably about 5 to 2000 C.PS. These paints
The composition and coating amount of each material should be taken into consideration so that the size of the entire recording sheet is 3 seconds or more, and these can be easily determined by experiments.

In addition, as the ink permeation preventive agent, there are also those which are applied for the purpose of forming an ink permeation preventive layer on the back surface of the base layer as shown in FIG. 1, and for example, SBR latex, ethylene vinyl acetate latex, acrylic latex, etc. In this method, a resin emulsion having a high film-forming property is applied to the base layer, and it is also desirable to add a filler to the ink permeation preventive agent in order to further improve the concealing property against ink strike-through. , Titanium oxide as a filler,
Examples include white fine particle pigments such as calcium carbonate and kaolin. Of course, the above-mentioned sizing agents for general paper can be added to these paints. When a filler is added, sodium polyacrylate, ammonium polyacrylate, sodium pyrophosphate, etc. are usually used as the anionic dispersant, and cationized polyvinyl alcohol, polyaminoamide fatty acid compound, low There are molecular cationized galactomannans and the like, and any of these types is added. Also in the case of this paint, it is desired to increase the coating viscosity of the paint to some extent for the same purpose as described above. In order to improve strike-through and hiding power of the ink, it is desirable to apply at least about 3 to ²⁰ g / m ^2, more preferably 5 to 15 g / m ² . Further, as a result, the composition of the above-mentioned coating material must be taken into consideration so that the size of the recording sheet becomes 3 seconds or more.

Examples of the method for applying the ink permeation preventive agent of the present invention include a size press, a roll coater, a blade coater, a bar coater, and a spray method.

The base layer of the present invention is composed of auxiliary agents such as pulp, filler, internally added sizing agent and retention aid, and if necessary, a material having a low affinity with ink can be added. The pulp is mainly composed of plant pulp such as wood pulp and cotton pulp, and recycled pulp from waste paper, and inorganic fibers such as glass fiber and synthetic pulp may be used together if necessary.

As the filler to be added internally to the base layer, calcium carbonate, clay, kaolin, acid clay, talc, synthetic silica, alumina, aluminum hydroxide, zinc oxide, calcium silicate, synthetic silicate, titanium oxide, diatomaceous earth, barium sulfate, Satin white, organic resin pigments and the like are generally used in the field of papermaking or paper processing, and there are many grades, but any of them can be used. In order to increase the opacity, those having a high refractive index such as titanium oxide and calcium carbonate and easily atomized are preferable, and in view of availability and economical efficiency, finely divided calcium carbonate is most preferable.

The ink receiving layer has an ink absorption capacity suitable for multicolor recording and sufficient ink absorbency immediately for drying, and has good color reproducibility,
It must be possible to obtain a recorded image with high recording density and uniform. For that purpose, the ink receiving layer should be a porous layer having a certain thickness using a material having an affinity for the ink, and the transparency of the porous layer should be increased. If the ink-receiving layer has no affinity for the solvent of the ink, the ink will not penetrate into the ink-receiving layer and the drying will be poor, and the recorded image will be destroyed by the flow or rubbing of the ink. Not suitable for. Also, if there is a material in the ink receiving layer that has no affinity for the dye in the ink, the dye will not be dyed to that material, so there will be uncolored portions in the recording dots and a uniform image cannot be obtained. . Therefore, when a water-based ink is used for ink jet recording, if a certain amount or more of the sizing agent is contained in the ink receiving layer, the penetration and drying of water as a solvent will be poor, so that the object of the present invention cannot be achieved. Further, when a certain amount of a material having no affinity for water and dye, such as synthetic pulp, is present, the portion is not colored and is uniform but does not form an image, so that the object of the present invention cannot be achieved.

Further, since the water-based ink mainly develops color by the principle of anti-corrosion mixing, the more transparent the ink receiving layer is, the less light scattering the better the color reproducibility of the ink and the clearer the image can be expected. That is, when the surface of the recorded ink receiving layer receives a certain amount of light energy, the light energy is sufficiently absorbed, and the smaller the scattering reflection, the higher the color density and the good color reproducibility.

The ink receiving layer of the present invention is composed of pulp, a filler, and an auxiliary agent such as a water-soluble resin for finely adjusting the quality and productivity.

The pulp constituting the ink receiving layer is wood pulp, cotton pulp and recycled pulp from waste paper. Unlike the base layer, do not use fibers or pulp that have no affinity for the ink solvent or dye. Therefore, in the case of water-based inks, it is necessary to avoid using a clear amount of glass fiber or synthetic pulp.

As the filler that can be used in the ink receiving layer, the same kind as that used in the base layer can be used, but it should be taken into consideration in selecting the filler so that the ink absorbing capacity is large and the light scattering reflection is small. In terms of transparency of the ink receiving layer, it is not always necessary to use a filler, but in order to further improve ink absorbency and control the shape and spread of ink dots to obtain clear images with high density and high resolution. It is preferable to use a filler such as ground calcium carbonate ground to a medium level or less. The transparency of the ink receiving layer in the present invention is the degree to which light incident on the ink receiving layer is scattered by the ink receiving layer. The more the light is scattered, the lower the transparency is, and the image looks whitish after recording. Therefore, the transparency of the ink receiving layer can be indexed by the specific scattering coefficient S by Kubelka-Munk, which indicates the degree of light scattering. Representative value of the non-scattering coefficients, wood pulp 200~700cm ² / g, synthetic pulp 900~1300cm ² / g, filler is 600~1000cm ² / g approximately. Not only does this value vary depending on the type of material,
Depending on the method of treatment, particle size, etc., some may exceed this range.

Since the value of S decreases as the beating degree of the pulp increases, it is a preferable method to use pulp having a high beating degree in order to reduce scattering reflection of the ink receiving layer and obtain clear recording. However, if the beating degree is too high, the number of voids that absorb ink will be small and the absorbability will be poor, so it is not preferable to make the beating degree too high.

A water-soluble resin is mixed with pulp in the ink receiving layer of the present invention, and is added for the purpose of imparting various characteristics such as improved printing quality of sheets, improved operability, and improved yield. As the water-soluble resin, starch, cation-modified starch, polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose and carboxymethyl cellulose, polyacrylamides, polyamide epichlorohydrin resin, polyvinyl pyridine, polyethylene oxide,
Polyvinylpyrrolidone, casein, gelatin, sodium alginate, sodium polystyrene sulfonate, sodium polyacrylate, starch-acrylonitrile graft polymer hydrolyzate, sulfonated chitin, carboxylated chitin and chitosan and their derivatives, and further polyethyleneimine, polydimethyl Diallylammonium chloride,
Polyalkylene polyamine dicyandiamide ammonium condensate, polyvinyl pyridinium halide, (meth)
Alkyl acrylate quaternary ammonium salt, (meth) acrylamidoalkyl quaternary ammonium salt, ω-chloro-
Examples thereof include poly (oxyethylene-polymethylene-alkyl quaternary ammonium salt) and polyvinylbenzyltrimethylammonium salt.

In order to obtain a clearer high-density recorded image,
As shown in the figure, it is a preferable method to apply or impregnate a minute amount of a very fine filler on the ink receiving layer to provide the fine coating layer 4. As such filler, synthetic silica, alumina, aluminum hydroxide and silicate are preferable, and silica is particularly preferable.

[Operation] The ink ejected from the printer reaches the surface of the ink receiving layer. Since the ink receiving layer is a porous layer composed of a material having an affinity for the solvent and dye of the ink, the ink rapidly penetrates into the ink receiving layer and is rapidly absorbed. The ink that has penetrated the ink receiving layer reaches the base layer, but since the base layer contains a sizing agent or an ink permeation preventive agent is applied to the back surface of the base layer, the ink that has permeated is the ink above the base layer or below the base layer. It can be suppressed by the permeation preventive agent, the recording density is improved, there is no strike-through of the ink, and absorption wrinkles can be suppressed.

The size of the strike-through is related to both the physical penetration of the ink and the visual penetration of the ink through the paper layer, so the opacity of the base layer or the ink permeation prevention layer should be a certain level or more. By improving the transparency,
The strikethrough is improved.

The extent of the ink spreading and permeating into the recording paper is naturally proportional to the amount of ink ejected per unit area, but is also related to the size and depth of the voids in the ink receiving layer. Not only by combining the conflicting materials of the multi-layer paper of the ink receiving layer and the base layer of the present invention, the presence of an ink scavenger or an ink permeation inhibitor mainly at the interface between the ink receiving layer and the base layer, or Further, by coating the ink permeation preventive agent on the base layer, it becomes possible to appropriately control the size and the degree of permeation of the ink dots, and the desired effect of strike-through prevention can be sufficiently obtained.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples. still,
In the following examples, parts and% indicate parts by weight of solid content and% by weight of solid content, unless otherwise specified.

Example 1 The recording sheet of this example has the structure shown in FIG.

350 ml of freeness (CSF) as a raw material pulp for the base layer B
80 parts of LBKP and 20 parts of NBKP with 450 ml of freeness (CSF) are mixed and used, and as a filler, calcite-based light calcium carbonate (spindle type, 50% average particle size 4.1 μm, BET specific surface area 5 m ² /
g) 20 parts and 0.02 part of the yield improving agent M (polyacrylamide cation modified product, 590 C.P. at 0.5% concentration) were added to prepare a base layer slurry.

On the other hand, as a raw material pulp for the ink receiving layer A, a freeness of 350 m
l LBK 100 parts, calcite-based heavy calcium carbonate as filler (amorphous, 50% average particle size 4.6 μm, BET specific surface area 3.4 m
² / g) 10 parts, and a yield improving agent M (polyacrylamide cation modified product, viscosity 0.5% and viscosity 590 C.PS) 0.02 parts were mixed to form an ink receiving layer slurry, so that these two raw materials were not mixed at all Base layer 45g / m ² , ink receiving layer
After adjusting to 30 g / m ² , both layers were superposed in the form of a wet paper to obtain a two-layer base sheet having a basis weight of 75 g / m ² as a whole by means of a multi-layer paper machine made of a combination of fourdrinier and fourdrinier.

The ink permeation preventive layer 3 is provided on the back surface of the base layer B of the base sheet.
Was set up. As a paint for the ink penetration inhibitor, 50 parts of SBR latex was added to 100 parts of titanium oxide (anatase type, specific gravity 3.9, 50% average particle diameter 0.3 μm) containing a dispersant,
Further, water was added to prepare a paint having a concentration of 35%. Apply 10g / m ^{2 of} solid content to the base layer with a Mayer bar,
A recording sheet 1 of Example 1 was obtained.

Example 2 The recording sheet of this example has the structure shown in FIG.

350 ml of freeness (CSF) as a raw material pulp for the base layer B
80 parts of LBKP and 20 parts of NBKP of 450 ml of freeness (CSF) are mixed and used, and kaolin (kaolinite genus,
Spherical aggregate, 50% average primary particle size 0.1 μm, specific gravity 2.2) 20
Parts, wet strength improver Polyamide epichlorohydrin resin
A slurry for the base layer was prepared by adding 0.3 part and 1.5 parts of a sulfuric acid band. Next, as the ink receiving layer A, L with a freeness of 350 ml
A slurry for an ink receiving layer was prepared by adding 1.5 parts of a sulfuric acid band to 100 parts of BKP. To obtain a base sheet of paper making two layers of the base layer 60 g / m ^2, a basis weight 90 g / m ² as a whole is adjusted to the ink-receiving layer 30 g / m ² by round net multi-cylinder multi-layer paper making paper machine.

The ink permeation preventive layer 3 was provided on the back surface of the base layer B of this base sheet. Surface sizing agent as an ink penetration inhibitor Anionic styrene acrylic copolymer (Hamacoat S-70
0, 20 parts by Misawa Ceramic Chemical Co., Ltd., 80 parts by weight of oxidized starch, adjusted to a concentration of 9%, and apply a solid content of 2.5 g / m ² to the base layer side of the above base sheet with a test size press machine. Thus, an inkjet recording sheet 1 of Example 2 was obtained. The ink permeation preventive agent permeates the base layer B to some extent to prevent ink permeation.

Example 3 The recording sheet of this example has the structure shown in FIG.

350 ml of freeness (CSF) as a raw material pulp for the base layer B
LBKP 80 parts and freeness (CSP) 450 ml NBKP 20 parts are mixed and used, and calcite-based light calcium carbonate (spindle type, 50% average particle size 4.1 μm, BET specific surface area 5 m ² /
g) 20 parts, internally added sizing agent alkyl ketene dimer (cationic, PH3.0, viscosity 30C.PS) 0.05 parts, wet strength improver polyamide epichlorohydrin resin 0.3 parts, retention improver M0.02 parts for base layer added A slurry was prepared.

On the other hand, as a raw material pulp for the ink receiving layer A, a freeness of 350 m
l LBKP 100 parts, calcite-based heavy calcium carbonate as filler (amorphous, 50% average particle size 4.6 μm, BET specific surface area 3.4 m
² / g) 10 parts, a wet strength improver polyamide epichlorohydrin resin 0.3 part, and a yield improver M 0.02 part were mixed to form an ink receiving layer slurry, which was made to prevent these two raw materials from being mixed with each other. Is 45 g / m ² and ink-cunk receptive layer A is adjusted to 35 g / cm ² by using a cylinder cylinder, and both layers are superposed in the form of wet paper, and the total basis weight is 80 g / m ² The base sheet for making paper was obtained by a combo multi-layer paper machine with a fourdrinier.

The ink permeation preventive layer 3 was provided on the back surface of the base layer B of this base sheet. As a paint as an ink penetration inhibitor,
Titanium oxide containing dispersant (anatase type, specific gravity 3.9, 5
50% of SBR latex was added to 100 parts of 0% average particle diameter 0.3 μm), and water was further added to prepare a paint having a concentration of 35%.
This coating material was applied to the base layer with a solid content of 10 g / m ² using a Mayer bar to prepare an inkjet recording sheet 1 of Example 3.

Example 4 The recording sheet of this example has the structure shown in FIG.

350 ml of freeness (CSF) as a raw material pulp for the base layer B
LBKP 80 parts and freeness (CSP) 450 ml NBKP 20 parts are mixed and used, and kaolin (kaolinite genus,
Spherical aggregate, 50% average primary particle size 0.1 μm, specific gravity 2.2) 20
Parts, ω-chloro-poly (oxyethylene-polymethylene-alkyl quaternary ammonium salt) 1.5 parts, sulfuric acid band
A slurry for a base layer added with 1.5 parts was prepared, and a base sheet B of a wet paper having a basis weight of 60 g / m ² was obtained from this slurry by using a square hand-made sheet tester (manufactured by Tozai Seiki Co., Ltd.), It was kept in the state before press dehydration.

Next, as an ink receiving layer A, 1.5 parts of sulfuric acid band was added to 100 parts of LBKP having a freeness of 350 ml to obtain a slurry for an ink receiving layer. From this slurry, a wet paper having a basis weight of 30 g / m ^{2 was} measured by a hand-making tester similar to the above. A paper ink receiving layer sheet A was obtained. Further, this sheet was laminated on the base paper sheet of the wet paper coated with the above-mentioned polymer to form a two-layer sheet, which was press dehydrated in accordance with the method for producing a test handmade sheet (JIS P8209) and dried. A two-layered base sheet having a basis weight of 90 g / m ² was obtained.

The ink permeation preventive layer 3 was provided on the back surface of the base layer B of this base sheet. As an ink penetration inhibitor, a surface sizing agent anionic styrene-acrylic copolymer (Hamacoat S-70
0, Misawa Ceramic Chemical Co., Ltd.) (50 parts) and oxidized starch (50 parts) were mixed, and water was added to adjust the concentration to 9%. An ink jet recording sheet 1 of Example 4 was obtained by applying a solid content of about 3.5 g / m ² with a Mayer bar and drying.

Comparative Example 1 Freeness (CSF) 400 ml LBKP100 as raw pulp
Part is used as a filler and calcite-based light calcium carbonate (spindle type, 50% average particle size 4.1 μm, BET specific surface area 5 m
² / g) 20 parts and the yield improver M 0.02 part were mixed to obtain a slurry. This slurry was dehydrated and dried by a conventional method using a square hand-made paper tester (manufactured by Tozai Seiki Co., Ltd.) to obtain a basis weight of 90 g /
An inkjet recording sheet of Comparative Example 1 having m ² was obtained.

Comparative Example 2 LBKP100 having a freeness (CSF) of 350 ml as a raw material pulp
Parts, and calcite-based soft calcium carbonate (spindle shape, 50% average particle size 4.1 μm, BET specific surface area)
Slurry was prepared by adding 20 parts of 5 m ² / g), 0.05 part of internally added sizing agent alkyl ketene dimer (cationic, PH3.0, viscosity 30 C.PS), and 0.02 part of retention aid M. The square hand from the slurry paper making tester dehydrated by a conventional method using (Tozai Seiki Co., Ltd.), comparison of dried basis weight of 90 g / m ² Example 2
To obtain an inkjet recording sheet.

Comparative Example 3 100 parts of LBKP having a freeness of 350 ml as a raw material pulp, kaolin (genus kaolinite, spherical aggregate, 50% average primary particle size)
20 parts of 0.1 μm, specific gravity 2.2) and 1.5 parts of sulfuric acid band were added to form a slurry. A sheet having a basis weight of 90 g / m ² was obtained from this slurry in the same manner as in Comparative Example 1. On the back surface of this base sheet, a surface sizing agent anionic styrene acrylic copolymer (Hamacoat S-700, Misawa Ceramic Chemical Co., Ltd.)
(Manufactured by Mitsui Chemicals Co., Ltd.), mixed with 50 parts of oxidized starch and 50 parts of water, and adjusted to a concentration of 9% by adding water.
^Two coatings and drying were performed to obtain an inkjet recording sheet of Comparative Example 3.

The characteristics of the inkjet recording sheets of Examples and Comparative Examples thus obtained were tested and evaluated by the following methods. The evaluation results are shown in Table-1.

(1) Recording density: Sharp color image printer IO-
4 color (black, cyan, magenta, yellow) solid recording (size 1.5cm x 2cm) is performed using 700, and the recorded portion is Macbeth density type (M, manufactured by Kollmorgn Corporation, M
The recording density was measured by cbeth RD915). The table shows the total of the measured values of the four colors, and 3.3 or more was considered good.

(2) Strikethrough: The back side of the recording portion of the recording sample used for recording density measurement was visually evaluated.

Evaluation A-There is no penetration of ink, and there is almost no penetration.

Evaluation B-There is no penetration of ink, and see-through is slightly observed.

Evaluation C-Almost no penetration of ink, but see-through was severe. Or, the ink penetrates heavily, but there is almost no see-through.

Evaluation D- Penetration of the ink was observed, and the see-through was intense.

(3) Bleed: Sharp color image printer IO-70
By using 0, red, green, and purple, which are made by superimposing three primary colors (each ink of cyan, magenta, and yellow), are alternately recorded as solid prints (size 1.5cm x 2cm), and they are adjacent to each other. The degree to which the ink started to flow to each other or one side was evaluated.

Evaluation A-No ink bleeding or bleeding started.

Evaluation B-Bleeding and flow of ink are small.

Evaluation C-Bleeding and bleeding of the ink are largely observed.

EFFECTS OF THE INVENTION As is clear from the above description, in a multi-layer paper comprising a base layer having high opacity and an ink receiving layer made of a material having an affinity for ink on one side of the base layer, the base layer By coating a material having an ink permeation-preventing ability on the surface not adjacent to the ink receiving layer, or by further adding a trace amount of a sizing agent and / or a cationic polymer to the base layer, conventional pulp fibers or the like can be obtained. The problem of simultaneously solving the problems of sufficient ink absorption and ink strike-through, which could not be obtained by a single sheet inkjet recording sheet, was able to be overcome. Furthermore, as a ripple effect, absorption wrinkles of the recording sheet caused by swelling and shrinking of the fiber due to the absorption of a large amount of ink are reduced, and the recording characteristics such as recording density are greatly improved, and a large amount of filler having high ink absorption is applied. The obtained product was comparable to the commercially available heavy coat type inkjet recording paper.

[Brief description of drawings]

1 to 4 are sectional views of the ink jet recording sheet of the present invention. A ... Ink receiving layer, B ... Base layer 1 ... Ink jet recording sheet of the present invention 2 ... Treatment agent-containing layer, 3 ... Ink permeation prevention layer 4 ... Fine coating layer

Claims (2)

[Claims] 1. A multi-layered paper comprising a base layer (B layer) obtained by combining 1 or 2 or more layers and an ink receiving layer (A layer), which is not adjacent to the A layer of the B layer. An ink jet recording sheet obtained by applying an ink permeation preventive to a sheet. 2. A sizing agent in the layer B according to claim 1 and / or
The inkjet recording sheet according to claim 1, further comprising a cationic polymer.