JPH02243381A - Ink jet recording sheet - Google Patents

Abstract

PURPOSE:To obtain an ink jet recording sheet having a sufficient ink absorptivity suitable for color recording and little strike through by applying an ink permeation control agent to the surface not adjoining an ink receptive layer of a base layer composed of one layer or two layers or more. CONSTITUTION:An ink receptive layer A and a base layer B are combined together and an ink permeation control agent is applied from the back of said base layer B to provide an ink permeation control layer 3 to form an ink jet recording sheet 1. To combine said ink receptive layer with the base layer, paper material of both layers are spectively prepared and combined by, e.g. a cylinder-type vat-type machine. As said ink permeation control agent, materials and paints having low affinity for water-color ink or hydrophobic property hindering permeation of said water-color ink can be used in addition to so-called surface sizing agent for ordinary paper. As said surface sizing agent, it is possible to cite enforced rosin sizing agent used for acid paper further reactive sizing agent such as alkylketene dimer used for neutral paper making, and self-fixing cationic resin sizing agent, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application J The present invention relates to recording paper for inkjet printers.

[Prior Art] In recent years, the demand for color printers has been increasing. Inkjet recording, which is a type of non-impact recording method, has received high praise in particular because it allows relatively high-speed color recording with a simple device. However, in order to obtain multicolor, high-speed, high-definition images in inkjet recording, there are still many points that must be overcome.

Viewed from the recording sheet side, this means that it has sufficient ink absorption and ink drying properties.

In particular, in order to perform multicolor recording, it is necessary to deal with the overlapping of multiple ink dots or an increase in the number of ink dots per unit area, so the ink absorption capacity of the recording layer is sufficiently large and high speed recording is possible. The ink dries quickly after fixing.

Inkjet recording uses two types of inkjet recording: the brain type, in which ink is absorbed into the cellulose fibers themselves, or the voids formed between the fibers or between filler and fibers, and the fine voids in the coating layer, which covers the paper surface as a support with filler and binder. It is roughly divided into coat types that absorb ink. Although coated type ink dots have a small spread, are circular in shape, and have excellent resolution, they have a small ink absorption capacity and slow ink absorption speed, making them unsuitable for multicolor recording with a large amount of ink, and they are also expensive. There is.

Recently, as printers have become faster, there has been a growing need for plain paper that is economical in terms of consumables and has a paper-like feel and texture.

Plain type paper technology has mainly been shown in three directions. One direction is, for example, Japanese Patent Application Laid-Open No. 53-491.
This is a technique disclosed in Japanese Patent Application Laid-Open No. 58-8685, etc. The former is a sheet filled with urea-formalin resin powder coated with a water-soluble polymer, and the latter is a sheet filled with synthetic silicate and glass fibers coated with a water-soluble polymer and impregnated. This is what I did. These inkjet recording sheets are characterized by improving ink absorption by adding specific fine powder to sizeless base paper and making them compatible with high-speed printing. This type of recording sheet consists of only an ink-receiving layer, so when multicolor recording with a large amount of ink is performed on this sheet, the ink spreads in the lateral direction of the paper and the ink dots smear and become larger, resulting in poor resolution. . In addition, since the ink penetrates deeply into the thickness direction, light is scattered by the upper layer of the recording sheet, resulting in a decrease in recording density, and back-out is a major problem, as it causes the printed area to show through and the ink to bleed through. .

Other directions are Special Publication No. 60-27588 and Special Publication No. 6
As seen in Japanese Patent No. 1-50795, an attempt is made to control the dot diameter by giving the sheet a fine size and suppressing ink absorption to some extent. The former is a sheet containing a wet paper strength enhancer and a small amount of surface coating paint applied so as not to cover the paper surface, and the Steckigt sizing degree is 3 seconds or less, and the latter is a sheet made of saponified petroleum resin. This is an inkjet recording sheet with a sizing agent coated on the surface of the paper. The effect of the sizing agent on these recording sheets suppresses the bleed-through and lateral spread of ink dots, which are the disadvantages of the above-mentioned technology, but the basic principle is that they are not suitable for multi-color recording due to poor ink absorption. There are some shortcomings.

Another plain type technology is JP-A-63
JP-A-118287 proposes a two-layer paper for inkjet recording. The basic idea of this disclosed technology is that the first layer is a support sheet mainly made of valve fibers, and the second layer is
The paper is uncoated, with a layer made of filler and valve fibers to improve recording density, but as mentioned earlier, no treatment is applied to color recording using aqueous ink, which requires a large amount of ink. This method does not solve the problem of ink strike-through, which is an important problem in inkjet recording on uncoated paper.

[Problems to be Solved by the Invention] The present invention provides a paper that maintains the feel and feel of uncoated paper, has uniform image quality, high recording density, and has sufficient ink absorbency suitable for multicolor recording. It is an object of the present invention to provide an inkjet recording paper with less strike-through.

[Means for solving the problem] As a result of repeated studies to solve the above-mentioned problems, we combined the ink-receiving layer (AI) and the base layer (B layer) consisting of one or more layers. An inkjet recording sheet consisting of an inkjet recording sheet in which an ink permeation inhibitor is completely coated on the surface of the B layer that is not adjacent to the A layer, or the B layer further contains a sizing agent and/or a cationic polymer. By doing so, the above problems were solved and the present invention was completed.

Typical structures of the inkjet recording sheet of the present invention are shown in FIGS. 1 to 4. In the figure, A is the ink receiving layer, and B is the ink receiving layer.
2 is a base layer, 2 is a processing agent-containing layer, 3 is an ink penetration prevention layer, 4 is a fine coating layer for the purpose of improving image quality and is a part of the ink receiving layer, 1 is an inkjet of the present invention It is a record sheet.

In FIG. 1, an inkjet recording sheet 1 is prepared by combining an ink receiving layer A and a base layer B, and applying an ink penetration preventive agent from the back side of the base layer B to provide an ink penetration preventive layer 3. Here, there are two cases in which the ink penetration inhibitor penetrates into the base layer B to some extent and the base layer B partially or completely acts as an ink penetration prevention layer, and two cases in which the ink penetration inhibitor hardly penetrates into the base layer and the base layer B acts as an ink penetration prevention layer 3. Ink penetration 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 a sizing agent and/or a cationic polymer to form the treatment agent-containing layer 2 are combined, the base layer B (the treatment agent-containing layer 2 ) and provided with an ink permeation prevention layer 3 to form a recording sheet 1. The purpose of the sizing agent and cationic polymer here is, first, to appropriately control ink penetration from the ink-receiving layer surface during inkjet recording, and second, an ink penetration inhibitor that is applied after forming the multilayer paper. The dye of the ink penetrating through the ink-receiving layer, especially if it contains a cationic polymer, is prevented from penetrating deeper into the ink-receiving layer A through the base layer B, while the applied ink It combines with a penetration inhibitor (anionic paint) to form an ink penetration prevention interface to improve ink penetration.

In the present invention, in order to combine the ink-receiving layer and the base layer, the paper stocks for the ink-receiving layer and the base layer are prepared respectively, and a paper machine such as a circular vat type, a suction former or an ultraformer, or a fourdrinier is used. Type (On-Top-Tw
in-Former) of Arcu-Former (T
ampella AB: manufactured by OY), IJltra-Tw
in-Former (@Kobayashi Seisaku Shinsei), Allad
This is carried out using a paper machine such as in-Former (manufactured by Sanki Tekko ■). The present invention is a recording sheet in which an ink-receiving layer and a base layer are combined using these paper machines to form a multi-layered sheet, and then an ink permeation preventive agent is applied to the back side of the base layer, and further, This shows that by containing a sizing agent and/or a cationic polymer in the base layer, an extremely excellent inkjet recording sheet with no ink strike-through can be obtained.

The first role of the base layer B and the ink permeation prevention layer 3 is to suppress "show-through" in which the ink is visible from the back surface when inkjet recording is performed on the recording sheet. The second role is to prevent the ink from penetrating so that the ink does not penetrate through the paper layer and reach the back side (sweep-through (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 deeper and more rapidly into the base layer. Therefore, opacity and size are important properties that the base layer should have, and JIS P8
Opacity measured by 138 is 75% or more, JISP81
It is preferable that the Steckigt sizing degree of the base layer (basis weight 60 g/rrr) measured in No. 22 is 3 seconds or more.

When the opacity is 75% or more, the ink that has passed through the ink-receiving layer and reached the base layer will have less see-through (show-through) that can be seen from the back side, and therefore less show-through (
Become. If the Steckigt sizing degree is 3 seconds or more, penetration of the ink into the base layer (strike-through) can be suppressed in the base layer, so that strike-through can be improved. The effect is particularly remarkable when a sizing agent is included in the ink penetration preventive agent applied from the back side of the base layer. However, depending on the type of printer, it is preferable not to apply too much size to the base layer, as ink may flow out in printers where the amount of ink is large and the ink receiving layer cannot accommodate the ink. do not have. If the sizing degree is too low, the ink will penetrate into the base layer, causing noticeable bleed-through, and the amount of ink remaining in the ink-receiving layer will decrease.
This is also undesirable because the recording density decreases and the sharpness of the image decreases. Therefore, the size is preferably 3 seconds or more and is so-called micro size, and is usually about 3 to 50 seconds.

In the base layer B of the present invention, since the ink penetration inhibitor is applied from the back side of the base layer B, a so-called general internal sizing agent is not necessarily required. However, in the present invention, as shown in FIG. 2, in order to appropriately control the ink penetration during recording or to prevent the ink penetration inhibitor from migrating to the ink receiving layer A, a small amount of sizing agent and/or
Alternatively, it is preferable to include a cationic polymer in the base layer B, and then apply the ink penetration inhibitor from the back side of the base layer B after the A layer and the B layer are combined. The sizing agents listed here include reinforced rosin sizing agents used for acidic paper making, petroleum resin sizing agents, emulsion type rosin sizing agents, alkenyl succinic acid type synthetic sizing agents, and alkyl ketene dimer and alkenyl sizing agents used for neutral paper making. In addition to common sizing agents such as reactive sizing agents such as phosphoric anhydride and self-fixing cationic resin sizing agents, cationic polymers can also be used. The amount of the sizing agent added is preferably a very small amount, preferably in the range of 0.01 to 2.5 parts per 100 parts of the bulb fibers of the base layer.
It is desirable to add 0.01 part to 5 parts per 00 parts. The thionic polymers include polyethyleneimine, polydimethyldiallylammonium chloride, polyalkylene polyamine dicyandiamide ammonium condensate, polyvinyl pyridium halide, (meth)acrylic acid alkyl quaternary ammonium salt, (meth)acrylamide alkyl quaternary Examples include ammonium salt, ω-chloro-poly(oxyethylene-polymethylene-alkyl quaternary ammonium salt), polyvinylbenzyltrimethylammonium salt, and the like.

Among these, cationic sizing agents and cationic polymers are particularly preferred, and in this case, it is preferable to use an anionic sizing agent or an anionic paint as an ink penetration inhibitor to be applied after forming the multilayer paper of the present invention. These cationic sizing agents and cationic polymers have the function of scavenging agents for ink, and when combined with anionic paints, the cationic polymer and anionic paint react in the base layer and become insolubilized. It becomes a permeation-blocking interface. These characteristics of the recording sheet improve the ink absorbency of printers and the like that use a large amount of ink, and have an excellent effect on ink strike-through.

As the ink penetration preventive agent of the present invention, in addition to so-called surface sizing agents for squeezed paper, materials and paints having hydrophobicity that have a low affinity for water-based inks or that inhibit the penetration of water-based inks are used. can.

Surface sizing agents include reinforced rosin sizing agents used for acidic paper making, petroleum resin sizing agents, emulsion type rosin sizing agents, alkenyl succinic acid type synthetic sizing agents, and alkyl ketene dimer and alkenyl succinic anhydride used for neutral paper making. Examples include reactive sizing agents such as acids, self-fixing cationic resin sizing agents, anionic or cationic acrylamides, and wax emulsions and silicones. It is also possible to add a water-soluble resin to the coating. In the case of this paint, the viscosity of the paint is 5 to 2000 C.P in order to prevent it from penetrating too deeply into the base sheet and inhibiting the ink from penetrating the ink receiving layer during inkjet recording.

S, degree is recommended. For these paints, consideration should be given to the composition of each material and the amount of coating so that the sizing degree of the recording sheet as a whole is 3 seconds or more, and these can be easily determined through experiments.

In addition, as shown in Figure 1, there are other ink penetration inhibitors that are applied to the back of the base layer for the purpose of forming an ink penetration prevention layer, such as SBR latex, ethylene acetate viratex, acrylic latex, etc. This is a method in which a resin emulsion with high film-forming properties is applied to the base layer, and it is also desirable to add a filler to the ink penetration preventive agent in order to further improve the hiding property against ink strike-through. Examples of the filler include fine white pigments such as titanium oxide, calcium carbonate, and kaolin. Of course, the above-mentioned sizing agents for general paper can also be added to these paints. When adding fillers, anionic dispersants such as sodium polyacrylate, ammonium polyacrylate, and sodium pyrophosphate are generally used, and cationic dispersants such as cationized polyvinyl alcohol, polyaminoamide fatty acid compounds, and There are molecular cationized galactomannans, etc., and any of these types are added. In the case of this paint as well, it is desired that the coating viscosity of the paint be increased to some extent for the same purpose as mentioned above. In order to improve ink bleed-through and hiding properties, it is desirable to apply at least 3 to 20 g/rtr, more preferably 5 to 15 g/r&. Further, the composition of the materials of the paint must be taken into consideration so that the size of the recording sheet is 3 seconds or more as a result.

Examples of the method for applying the ink penetration preventive agent of the present invention include size press, roll coater plate spray method, and the like.

The base layer of the present invention is composed of auxiliary agents such as a valve, a filler, an internal sizing agent, and a retention aid, and if necessary, a material having low affinity with the ink can also be added.

The bulbs are mainly vegetable bulbs such as wood bulbs and cotton bulbs, and bulbs recycled from waste paper, and inorganic fibers such as glass fibers and synthetic bulbs may be used in combination as necessary.

Fillers added to the base layer include calcium carbonate, clay, kaolin, acid clay, talc, synthetic silica, alumina, aluminum hydroxide, zinc oxide, calcium silicate,
Synthetic silicates, titanium oxide, diatomaceous earth, barium sulfate, satin white, organic resin pigments, and the like are generally used in the paper manufacturing or paper processing field, and there are many grades of these, and any of them can be used. In order to increase the opacity, it is preferable to use titanium oxide, calcium carbonate, or other materials that have a high refractive index and are easily atomized, and in consideration of availability and economy, finely divided calcium carbonate is most preferable.

The ink-receiving layer has an ink-absorbing capacity and drying property suitable for multicolor recording, that is, sufficient ink-absorbing property, and has good color reproducibility.
It must not be possible to obtain a high recording density (and a homogeneous recorded image).To achieve this, the ink-receiving layer must be made of a porous layer with a certain thickness using a material that has an affinity for ink. , the transparency of the porous layer should be high.

If the ink-receiving layer has no affinity for the ink solvent, the ink will not penetrate into the ink-receiving layer and will dry poorly, causing the recorded image to collapse due to friction when the ink starts to flow. This is because multi-color recording with a large amount of ink is required. Not suitable for Furthermore, 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, resulting in uncolored areas in the recorded dots, making it impossible to obtain a homogeneous image. . Therefore, when using aqueous ink for inkjet recording, if a certain amount or more of a sizing agent is contained in the ink-receiving layer, water penetration and drying (as a result, the object of the present invention cannot be achieved). If a certain amount or more of a material that does not have affinity for water and dyes exists, such as in a synthetic bulb, the object of the present invention cannot be achieved because that part will not be colored and a homogeneous image will not be formed.

Furthermore, since water-based inks develop color mainly on the principle of subtractive color mixing, the more transparent the ink-receiving layer is with less light scattering, the better the color reproducibility of the ink and the clearer the image can be expected. That is, when a recorded ink receiving layer receives a certain amount of light energy on its surface, the more the light energy is absorbed and the less scattered reflection there is, the higher the color density and the better color reproducibility can be obtained.

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

The bulbs that make up the ink-receiving layer are wood pulp, cotton bulbs and recycled bulbs from waste paper. No fibers or bulbs are used that, unlike the base layer, have no affinity for the ink's solvent or dye. Therefore, in the case of water-based inks, the incorporation of significant amounts of glass fibers or synthetic bulbs must be avoided.

The fillers that can be used in the ink-receiving layer can be the same types as those that can be used in the base layer, but when selecting fillers, consideration should be given to having a high ink absorption capacity (low scattering and reflection of light). .

In terms of the transparency of the ink-receiving layer, it is not necessary to use fillers, but it is necessary to use fillers to further improve ink absorption, control the shape and spread of ink dots, and obtain clear images with high density and resolution. It is preferable to use a filler such as ground calcium carbonate that has been crushed to a fine degree. The transparency of the ink-receiving layer in the present invention refers to the degree to which light incident on the ink-receiving layer is scattered by the ink-receiving layer, and the more light is scattered, the lower the transparency is, and the ink-receiving layer looks whitish after recording. Therefore, the transparency of the ink-receiving layer can be determined by the Kubelka-Munk specific scattering coefficient S, which indicates the degree of light scattering. Typical values of non-scattering coefficient are: Wood bulb 200-7000m2/g1 Synthetic bulb 900-1
300cm27g, filler is 600~1000 crn2
/z. This value varies not only depending on the type of material, but also varies depending on the processing method, particle size, etc., and some particles exceed this range.

Since the value of S decreases as the softness of the bulb increases, it is preferable to use a bulb with high softness in order to reduce the scattered reflection of the ink-receiving layer and obtain clear recording. However, if the degree of beating is too high, there will be fewer voids that absorb ink, resulting in poor absorbency, so it is not preferable to increase the degree of beating too high.

A water-soluble resin is mixed with a valve and added to the ink-receiving layer of the present invention for the purpose of imparting various properties such as improving sheet printing quality, improving operability, and improving yield. Water-soluble resins include starch, cationically modified starch, polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose and carboxymethyl cellulose, polyacrylamides, polyamide epichlorohydrin resin,
Polyvinyl pyridine, polyethylene oxide, polyvinyl pyrrolidone, casein, gelatin, sodium alginate, sodium polystyrene sulfonate, sodium polyacrylate, starch-acrylonitrile graft polymer hydrolyzate, sulfonated chitin, carboxylated chitin and chitosan and their derivatives , further polyethyleneimine, polydimethyldiallyl ammonium chloride, polyalkylene polyamine dicyandiamide ammonium condensate, polyvinyl pyridium halide, (meth)acrylic acid alkyl quaternary ammonium salt, (meth)acrylamide alkyl quaternary ammonium salt, ω-chloro- Examples include poly(oxyethylene-polymethylene-alkyl quaternary ammonium salt) and polyvinylbenzyltrimethylammonium salt.

In order to obtain even clearer high-density recorded images,
As shown in the figure, it is a preferable method to further apply or impregnate a very small amount of a very fine filler on the ink-receiving layer to provide a fine coating layer 4. As such fillers, synthetic silica, alumina, aluminum hydroxide, and silicates are preferred, with silica being particularly preferred.

[Operation] 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 that has an affinity for the ink's solvent and dye, the ink quickly penetrates through the ink-receiving layer and is rapidly absorbed. The ink that has permeated through the ink receiving layer reaches the base layer, but since the base layer contains a sizing agent or an ink penetration inhibitor is applied to the back side of the base layer, the ink that has permeated will reach the ink above or below the base layer. Suppressed by penetration inhibitor, recording density is improved and there is no ink bleed through.
It can also suppress absorption wrinkles.

The size of bleed-through is related to both the physical degree of ink penetration and the visual see-through of ink through the paper layer, so it is important to increase the opacity of the base layer or ink penetration prevention layer above a certain level. Transparency is improved by
See-through is further improved.

The degree of spread and penetration of ink onto recording paper is naturally proportional to the amount of ink applied per unit area, but it is also related to the size and depth of the voids in the ink-receiving layer. In addition to combining the contradictory materials of the ink-receiving layer and the base layer of the multilayer paper of the present invention, by providing an ink scavenger or/an ink penetration inhibitor mainly at the interface between the ink-receiving layer and the base layer, or Furthermore, by applying an ink penetration inhibitor to the base layer, it is possible to appropriately control the size of the ink dots and the degree of penetration, and the intended purpose of preventing strike-through can be sufficiently achieved.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples. still,
In the following examples, parts and percentages refer to parts by weight of solid content and weight percent of solid content, unless otherwise specified.

′! iJL! l! ! L1 The recording sheet of this example has the structure shown in FIG.

Freeness (c, s, p
) 350ml 80 parts of LBKP, Freeness (C,S.

F) Mix and use 450ml of 20 parts of NBKP, and add calcite-based light calcium carbonate (spindle-shaped,
50% average particle size4. Lμm, BET specific surface area 5ffr/
g) 20 parts, retention improver M (polyacrylamide cation modified product, 590 C, P at a concentration of 0.5%) 0
．． A base layer slurry to which 0.02 parts was added was prepared.

On the other hand, Freeness 35 is used as a raw material valve for the ink receiving layer A.
0ml of LBKP 100 parts, calcite-based heavy calcium carbonate (amorphous, 50% average particle size 4.6μ) as filler
m, BET specific surface area 3.4 I/g) to part, yield improver M (polyacrylamide cation modified product, concentration 0-
Viscosity 590C,P,S,) at 5% 0. 02 parts were mixed to make an ink receiving layer slurry, and the base layer was 45g/rr so that these two raw materials would not be mixed at all. The ink-receiving layer was adjusted to 30 g/rtr, and both layers were stacked in a wet paper state to give a total weight of 175 g/rrr.
A base sheet for layer papermaking was obtained using a multilayer paper machine with a combination of cylinder and fourdrinier.

An ink penetration prevention layer 3 is formed on the back side of the base layer B of this base sheet.
has been established. The paint for the ink penetration inhibitor is titanium oxide (anatase type, specific gravity 3.9.50%) containing a dispersant.
Average particle size: 0.3 μm) 100 parts of SBR latex 5
0 parts was added, and water was further added to prepare a paint with a concentration of 35%. This paint was applied to the base layer with a solid content of 10 g/m' using a Mayer bar to obtain the recording sheet 1 of Example 1.

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

Freeness (C, S, F) as raw material valve for base layer B
80 parts of 350ml LBKP, 7. (C,S
.

P) Mix and use 450ml of 20 parts of NBKP, and add kaolin (kaolinite, spherical aggregates,
Part % average - order particle size 0. 1μm5 specific gravity 2゜2) 20 parts, wet strength same agent polyamide epichlorohydrin resin 0
．． A slurry for the base layer was prepared by adding 3 parts of sulfuric acid and 1.5 parts of sulfate, and then Freeness 35 was prepared as the ink receiving layer A.
A slurry for an ink-receiving layer was prepared by adding 1.5 parts of aluminum sulfate to 100 parts of 0 ml of LBKP. A base layer of 60 g/d and an ink receiving layer of 30 g/d were adjusted using a multi-layer paper machine with multiple cylinders, resulting in an overall paper weight of 190 g/r.
A two-layer base sheet of rl was obtained.

An ink permeation prevention layer 3 was provided on the back surface of the base layer B of this base sheet. Anionic styrene acrylic copolymer (Hamacoat S-70) is used as a surface sizing agent as an ink penetration preventive agent.
0, manufactured by Misawa Ceramic Chemical ■) and 80 parts of oxidized starch.The concentration was adjusted to 9%, and a solid content of 2.5 g/d was applied only to the base layer side of the base sheet using a test size press. Thus, inkjet recording sheet 1 of Example 2 was obtained. This ink penetration inhibitor penetrates into the base layer B to some extent to prevent ink penetration.

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

Freeness (C, S, F) as raw material valve for base layer B
80 parts of 350ml LBKP, Freeness (C,S.

F) Mix and use 450ml of 20 parts of NBKP, and add calcite-based light calcium carbonate (spindle-shaped,
50% average particle size 4.1μm, BET specific surface area 5n (7g
) 20 parts, internal sizing agent alkyl ketene dimer (cationic, PH3.0, viscosity 30C, P, S,) 0.
05 parts, wet strength improver polyamide epichlorohydrin resin 0. A base layer slurry IJ- was prepared in which 0.02 parts of a retention improver M was added.

On the other hand, Freeness 35 is used as a raw material valve for the ink receiving layer A.
0ml of LBKP 100 parts, calcite-based heavy calcium carbonate as filler (amorphous, 50% average particle size 4.6μm)
, BET specific surface area 3.4 I/g) to part, wet strength improver polyamide epichlorohydrin resin 063 parts, and retention improver Mo2O 3 parts to make an ink receiving layer slurry, making sure that these two raw materials do not mix at all. The base layer B was adjusted to 45 g/d, the in-tank receiving layer A was adjusted to 35 g/m using one circular mesh, and both layers were superimposed in the state of wet paper to give a total basis weight of 80 g/d. g/
A two-layer base sheet of m was obtained using a combination multi-layer paper machine with a fourdrinier screen.

An ink permeation prevention layer 3 was provided on the back surface of the base layer B of this base sheet. As a paint that acts as an ink penetration inhibitor,
Titanium oxide containing a dispersant (anatase type, specific gravity 369)
．． 50% average particle size 0. A paint with a concentration of 35% was prepared by adding 50 parts of SBR latex to 100 parts of SBR latex (3 μm) and further adding water. It was called a recording sheet 1.

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

Freeness (C, S, F) as raw material pulp for base layer B
80 parts of 350ml LBKP, Freeness (C,S.

F) Mix 20 parts of 450 inl of NBKP, and add kaolin (kaolinite, spherical aggregates,
50% average-order particle size 0. 1 μm, specific gravity 2°2) 20 parts, ω-chloro-poly(oxyethylene-polymethylene-
A slurry for the base layer was prepared by adding 1.5 parts of alkyl quaternary ammonium salt and 1.5 parts of sulfuric acid. From this slurry, a square hand paper tester (manufactured by Tozai Seiki ■) was used to test 160 g of tsuboj/ A base layer sheet B of the wet paper of A was obtained and kept in the state before press dehydration.

Next, as the ink receiving layer A, LB with a freeness of 350 m1
A slurry for an ink-receiving layer was obtained by adding 1.5 parts of band sulfate to 100 parts of KP. From this slurry, an ink-receiving layer sheet A of wet paper with a tsubo fi of 30 g/m was obtained using the same hand-paper tester as above. Ta. Furthermore, this sheet was superimposed on the base layer sheet of wet paper coated with the polymer described above to form a two-layer sheet, which was then fabricated using the test handsheet production method (JI).
Press dehydration and drying were performed according to SP8209) to obtain a two-layer base sheet with a basis weight of 90 g/m.

An ink permeation prevention layer 3 was provided on the back surface of the base layer B of this base sheet. As an ink penetration inhibitor, surface sizing agent anionic styrene acrylic copolymer Kuhama Coat S-7
00, manufactured by Misawa Ceramic Chemical ■) and 50 parts of oxidized starch were mixed and water was added to adjust the concentration to 9%. The solid content is approx. 3. Inkjet recording sheet 1 of Example 4 was obtained by applying 5 g/rrr and drying.

Freeness (C, S, F) 400 as a raw material valve
ml of LBKP was used, and 20 parts of calcite-based light calcium carbonate (spindle shape, 50% average particle diameter 4.I μrn, BET specific surface area 5rd/g) as a filler and 0.02 parts of a retention improver M were mixed therein. and obtained slurry. This slurry was dehydrated and dried in a conventional manner using a square hand-made paper tester (manufactured by Tozai Seiki) to give a volume of 190 g/
An inkjet recording sheet of Comparative Example 1 of rd was obtained.

Freeness (C, S, F) as raw material pulp 350
ml of LBKP was used, 20 parts of calcite-based light calcium carbonate (spindle shape, 50% average particle diameter 4.1 μm, BET specific surface area 5 m'/g) was added as a filler, and alkyl ketene dimer (cationic sizing agent) was added as a filler. sex, PH
3.0, viscosity 30 C, P, S,) 0.05 part and a retention improver MO.02 parts were added to prepare a slurry.

This slurry was dehydrated and dried in a conventional manner using a square hand paper tester (manufactured by Tozai Seiki ■) to a basis weight of 90 g/r.
An inkjet recording sheet of Comparative Example 2 of d was obtained.

Comparative Example 3 LBKP10 with freeness 350m1 as raw material valve
0 parts, kaolin (genus kaolinite, spherical aggregates, 50
%Average-order particle size 0. 1μm1 specific gravity 2.2) 20 parts,
Sulfate band 1. 5 parts were added to form a slurry. From this slurry, tsubo J190 g/rr was prepared in the same manner as in Comparative Example 1.
? I got a sheet of A surface sizing agent of anionic styrene acrylic copolymer (Hamacoat S-700, manufactured by Misawa Ceramic Chemical ■) is applied to the back side of this base sheet.
50 parts of oxidized starch were mixed and water was added to adjust the concentration to 9%, and the solid content was approximately 2.5g/
The inkjet recording sheet of Comparative Example 3 was obtained by coating and drying.

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

(1) Recording density: Sharp Color Image Printer 10
Solid recording in 4 colors (black, cyan, magenta, yellow) using -700 (size 1.5cm x 2cm)
The recorded portion is converted into Macbeth density form (Kollrtr).
Manufactured by Orgen Corporation, Mcbeth
Recording density was measured using RD915). The table shows the total of the measured values for the four colors, and a value of 3.3 or higher was considered good.

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

Rating A - There is no ink penetration at all and almost no see-through.

Rating B - There is no ink penetration at all, and some see-through is seen.

Rating: C - There is almost no penetration of the ink, but there is severe see-through. Or, the ink penetrates heavily, but there is almost no see-through.

Rating: D - Penetration of the ink was observed, and the see-through was also severe.

(3) Bleeding: Sharp color image printer l0-
700, continuous solid recording (size 1.5 cm x 2 cm) of red, green, and purple created by overlapping the three primary colors (cyan, magenta, and yellow inks) was performed alternately, and the adjacent The degree to which the inks flowed to each other or to one side was evaluated.

Rating A - There is no ink bleeding or running.

Rating B - There is little ink bleeding or running.

Rating: C - Ink bleeding and running are noticeable.

[Effects of the Invention] As is clear from the above description, in a multilayer paper made of a highly opaque base layer 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 applying a material that has the ability to prevent ink penetration on the surface that is not adjacent to the ink-receiving layer, or by further adding a small amount of sizing agent and/or cationic polymer to the base layer, conventional valve fibers, etc. We were able to overcome the problem of simultaneously solving the problem of sufficient ink absorption and ink bleed through, which could not be achieved with the constituent single-sheet inkjet recording sheet. Furthermore, as a ripple effect, absorption wrinkles on the recording sheet, which are caused by swelling and contraction of fibers due to absorption of a large amount of ink, are reduced.
In addition, recording characteristics such as recording density have been greatly improved,
A paper comparable to commercially available heavy-coat type inkjet recording paper coated with a large amount of highly ink-absorbing filler was obtained.

[Brief explanation of drawings]

1 to 4 are cross-sectional views of the inkjet recording sheet of the present invention. A... Ink-receiving layer, B... Base layer ■... Inkjet recording sheet of the present invention 2... Processing agent-containing layer,
3... Ink penetration prevention layer 4... Fine coating layer

Claims (2)

[Claims] (1) A multilayer paper consisting of a base layer (B layer) made of one or more layers and an ink-receiving layer (A layer), with ink on the side of the B layer that is not adjacent to the A layer. An inkjet recording sheet coated with a penetration inhibitor. (2) The inkjet recording sheet according to claim 1, wherein the B layer according to claim 1 contains a sizing agent and/or a cationic polymer.