JP3172298B2 - Inkjet recording sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording sheet for recording using ink, and more particularly to an ink-jet recording sheet in which swelling of the sheet surface after ink-jet recording, ink bleeding and background contamination are significantly reduced. It is about.

[0002]

2. Description of the Related Art Ink-jet recording is a method in which minute droplets of ink are made to fly and adhere to a recording sheet such as paper according to various operating principles, thereby recording images and characters. It has features such as easy multi-coloring, great flexibility in recording patterns, and no need for development-fixing.
It is rapidly spreading in various uses as a recording device for various figures and color images including kanji. Furthermore, the image formed by the multi-color ink jet method is compared with the multi-color printing by the plate making method and the printing by the color photographic method,
It is possible to obtain comparable records. In applications where the number of copies required is small, it is being widely applied to the field of full-color image recording because it is cheaper than the photographic technique.

As recording sheets used in the ink jet recording system, efforts have been made in terms of apparatuses and ink compositions in order to use high-quality paper or coated paper used for ordinary printing and writing. However, with the improvement of the performance of ink jet recording apparatuses such as high-speed, high-definition and full-color apparatuses, and expansion of applications, more advanced characteristics are also required for recording sheets. That is, as the recording sheet, the density of the print dots is high, the color tone is bright and vivid, the ink does not flow out or bleeds even when the ink dots are quickly absorbed and the print dots overlap. High image reproducibility is required such that the diffusion in the direction is not unnecessarily large and the periphery is smooth and not blurred.

Several proposals have hitherto been made in response to such demands. For example, an ink-receiving layer serving as a void layer containing a silica-based pigment as a main component is provided on the surface of the support to improve the ink absorbency (JP-A-52-9074 and JP-A-58-72495). Gazette). In order to increase the ink absorption by this ink receiving layer and obtain print dots having high print dot density and no ink bleeding, JP-A-55-51583 and JP-A-56-157 disclose non-colloidal silica. There is a proposal to mix powder. In addition, focusing on the fact that the color and sharpness are in the distribution state of the dye in the ink in the ink receiving layer, a proposal has been made to use a specific agent that adsorbs the dye component (JP-A-55-144172). It has been done.

[0005] Another problem after ink jet recording is the occurrence of undulation on the sheet surface after printing. If undulations are present on the recording sheet surface after printing, there is a deterioration in the aesthetic appearance that is organoleptically evaluated even though the image reproducibility is excellent. This undulation is the occurrence of irregularities due to the expansion and contraction of the wood pulp in the support layer due to the penetrated ink. Therefore, preventing ink from penetrating into the support layer is a measure to avoid undulation, but this is equivalent to absorbing a large amount of ink in the ink receiving layer, and increasing the number of ink receiving layers. In addition, peeling (powdering) of the coating layer caused by the binder of the ink receiving layer occurs.

However, suppressing ink penetration without increasing the number of ink receiving layers is equivalent to reducing the amount of voids in the ink receiving layer and the support. As a result, the amount of voids in the ink receiving layer and the support is reduced. This reduces the penetration of the ink into the ink-receiving layer and the support, causing the ink to become undried. While the sheet is being conveyed, the rubbing of the dots is caused by contact with devices around the conveying device, and rubbing of the dots called background dirt occurs. When this rubbing stain occurs over a wide area, not only the non-image area becomes dirty and the appearance is impaired, but also when the area is extremely narrow, adjacent dots come in contact with each other, and the sharpness accompanying the enlargement of the dot and the color due to color mixing are reduced. And the image reproducibility is greatly deteriorated.

In particular, due to the recent increase in visualization orientation, ink jet recording sheets are required not only for sharpness and color, but also for sheet flatness after printing. Further, the flatness of the sheet surface after printing is also related to the transportability in the ink jet recording apparatus, and undulation is generated by printing. If the undulation is large, paper jam may occur in the ink jet recording apparatus. For this reason, it is necessary to have excellent aesthetics characteristics without ink bleeding and little undulation on the sheet surface after printing, but it is difficult to improve these contradictory characteristics.

[0008]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to reduce the undulation of the sheet surface after printing,
An object of the present invention is to provide a coated ink jet recording sheet in which bleeding of ink and background stain related to sharpness and color are significantly reduced.

[0009]

Means for Solving the Problems The present inventors have conducted various studies on the ink jet recording sheet, and as a result,
In a support composed mainly of wood pulp and pigment,
It has been found that the object of the present invention can be achieved by setting the pigment content in the support and the internal bond strength of the support to specific ranges. That is, the present invention relates to an ink jet recording sheet in which at least one or more ink-receiving layers are provided on a support composed mainly of wood pulp and a pigment, wherein the pigment content in the support is 5%. a ~ 35 wt%, and internal bond strength of the recording sheet 150 to 45
Another object of the present invention is to provide an ink jet recording sheet characterized by having a weight of 5 g / cm.

[0010] The internal bonding strength of the ink jet recording sheet according to the present invention is a parameter indicating the strength in the thickness direction of a support structured mainly of wood pulp and pigment in the thickness direction. It has been found that the internal bond strength and the pigment content are entangled and related to swell after printing and ink bleeding.

[0011] The internal bonding strength according to the present invention is determined by Tappi Usef.
It is measured by ul Methods 403, and usually the support is often measured. However, since the solvent in the coating liquid when applied to the support surface penetrates to the center of the support and causes a structural change in the support, the internal bond strength of the support changes, so the actual The measurement is preferably performed on a sheet in a printed state. When the internal bonding strength is low, the support is easily deformed by an externally applied force, and when the internal bonding strength is high, the support is hardly deformed. The undulation on the sheet surface after printing is caused by the expansion and contraction of the wood pulp due to the ink that has penetrated to the support layer, and this undulation can be avoided by suppressing this expansion and contraction, that is, by increasing the internal bond strength. I found something. However, in order to increase the internal bond strength, it is necessary to increase the amount of a polyacrylamide-based or polyacrylamide-based additive called a binder or a paper strength agent. The improvement in sizing property is accompanied by the improvement in the sizing property, but the bleeding of the ink is improved.

The internal bond strength of the support according to the present invention is determined by the structure of the support in which wood pulp and wood pulp, wood pulp and pigment, and pigment and pigment are combined. In addition, the sizing property related to ink penetration is based on the chemical aspect determined by the static state of the penetrating ink and the support and the physical aspect determined by the gap of the support as indicated by capillary penetration. Have. In particular, internal bond strength and sizing exist in a contradictory relationship, for example, an increase in pigment content in the support reduces the development of strength caused by hydrogen bonding between wood pulp and wood pulp. Although the internal bond strength is deteriorated, voids are increased due to the pigment and the structure formed by the pigment, and the above-described physical side promotes penetration.

From the above, it is considered that in order to satisfy the object of the present invention, an ink jet recording sheet may be formed by setting the pigment content in the support and the internal bond strength to be high. However, even if the internal bond strength and the pigment content are increased, the swell of the sheet surface after printing is improved, but the penetration of the ink is delayed after printing, and the background stain is generated.
Only when the internal bond strength is within a specific range of 150 to 455 g / cm and the pigment content is within a specific range of 5 to 35 % by weight, preferably 5 to 30% by weight, there is no swelling of the sheet surface after printing and ink bleeding. It was found that an ink jet recording sheet having a small amount was obtained.

Although the coating amount of the ink receiving layer is not particularly limited, if it is too small, the ink absorbency is as good as the non-coat type ink jet recording sheet, but the image density, color and sharpness are low. Feathering occurs. Also, if the coating amount is too large, the drying load in the drying step after coating or impregnation increases, and not only does the productivity decrease due to a decrease in the coating or impregnation speed, but also when drying under high load, the ink receiving layer The binder in the coating composition constituting (1) moves to the surface of the ink receiving layer together with the solvent that evaporates, and reduces the amount of voids on the surface. The problem which occurs in the ink receiving layer having a large coating amount depends on the concentration of the coating composition and the ability of the drying step, but is preferably 1 to 10 g / m ² . In the present invention, a back coat layer may be provided. The coating amount of the back coat layer is not particularly limited, and is preferably selected according to the coating or impregnating apparatus and the ability of the drying step.

The support used in the present invention is composed mainly of wood pulp and pigment. As wood pulp, chemical pulp such as LBKP and NBKP, GP, PG
Including mechanical pulp such as W, RMP, TMP, CTMP, CMP and CGP, pulp such as waste paper pulp such as DIP, etc., if necessary, conventionally known pigments and binders and sizing agents and fixing agents, retention agents, cationization And various additives such as paper-strengthening agents are mixed by using at least one of them, and the support can be manufactured by various apparatuses such as a fourdrinier paper machine, a circular net paper machine, and a twin wire paper machine. Neutral and alkaline paper can be formed. Further, an ink receiving layer may be provided on the support as it is, or a size press using starch, polyvinyl alcohol, or the like, or an ink receiving layer may be provided after providing an anchor coat layer. Further, a calender such as a machine calender, a TG calender, and a soft calender may be used for the purpose of controlling the flattening of the support.

One or more known white pigments can be used in the support, ink receiving layer and back coat layer used in the present invention. For example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate,
Barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina , Lithopone, zeolite, hydrohaloysite, magnesium carbonate, white inorganic pigments such as magnesium hydroxide, styrene-based plastic pigments, acrylic-based plastic pigments,
Organic pigments such as polyethylene, microcapsules, urea resins, melamine resins and the like can be mentioned. Among the above, as the white pigment contained as the main component in the ink receiving layer, a porous inorganic pigment is preferable, and a porous synthetic amorphous silica, a porous magnesium carbonate, a porous alumina, and the like,
Particularly, a porous synthetic amorphous silica having a large pore volume is preferable.

Examples of the adhesive include polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, casein, gelatin,
Soy protein, silyl-modified polyvinyl alcohol, etc .; conjugated diene-based copolymer latex such as maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; polymer or copolymer of acrylate and methacrylate Acrylic polymer latex such as polymer, acrylic acid and methacrylic acid polymer or copolymer; vinyl polymer latex such as ethylene vinyl acetate copolymer; or functional group such as carboxyl group of these various polymers Functional group-modified polymer latex by contained monomer; water-based adhesive such as thermosetting synthetic resin such as melamine resin and urea resin; polymethyl methacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride
Synthetic resin-based adhesives such as vinyl acetate copolymer, polyvinyl butyral, and alkyd resin are used, and one or more kinds are used.

Further, other additives include a pigment dispersant, a thickener, a flow improver, an antifoaming agent, a foam inhibitor, a release agent,
Blowing agents, penetrants, coloring dyes, coloring pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, anti-binders, water-proofing agents, wet paper strength enhancers, dry paper strength enhancers, etc. It can also be blended.

The method of coating and impregnating the support of the present invention with an ink receiving layer or a back coat layer includes various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, short dwell coaters,
Various devices such as a size press can be used on-machine or off-machine. After coating or impregnation, finishing may be performed using a calendar such as a machine calendar, a TG calendar, a super calendar, or a soft calendar.

The inks according to the present invention include the following colorants:
This is a recording liquid composed of a liquid medium and other additives. Examples of the coloring agent include a direct dye, an acid dye, a basic dye, a reactive dye, and a water-soluble dye such as a food colorant.

As the solvent for the 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,
C1-C4 alkyl alcohols such as tert-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; acetone;
Ketones or ketone alcohols such as diacetone alcohol; ethers such as tetrahydrofuran and dioxane;
Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol;
Alkylene glycols having 2 to 6 alkylene groups such as propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin, ethylene glycol methyl ether, diethylene glycol And lower alkyl ethers of polyhydric alcohols such as methyl (or ethyl) ether and triethylene glycol 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 preferred. Other additives include, for example, P
Examples include an H regulator, a metal sequestering agent, a fungicide, a viscosity modifier, a surface tension regulator, a wetting agent, a surfactant, and a rust inhibitor.

The ink-jet recording sheet in the present invention is not limited to use as an ink-jet recording sheet, but may be used as any recording sheet using a liquid ink at the time of recording. For example, a heat-fusible substance, a heat-fusible ink containing a dye or pigment as a main component, applied on a thin support such as a resin film, high-density paper, or synthetic paper, is heated from the back surface, and the ink is heated. An image-receiving sheet for thermal transfer recording, which is melted and transferred, an ink-jet recording sheet, which heats and melts a hot-melt ink to form fine droplets, and performs flight recording, an ink-jet recording sheet using an ink in which an oil-soluble dye is dissolved in a solvent, photopolymerization And an image receiving sheet corresponding to a photosensitive pressure-sensitive donor sheet using microcapsules containing a type monomer and a colorless or colored dye / pigment. What these recording sheets have in common is
The point is that the ink is in a liquid state during recording. The liquid ink permeates or spreads in the depth direction or the horizontal direction of the ink receiving layer of the recording sheet until it hardens, solidifies or fixes. The above-described various recording sheets require absorptivity according to each system, and the inkjet recording sheet of the present invention may be used as the above-described various recording sheets. Further, the ink jet recording sheet of the present invention may be used as a recording sheet for heating and fixing an electrophotographic recording type toner widely used in copying machines, printers and the like.

[0023]

In the ink jet recording sheet according to the present invention, if the content of the pigment in the support is less than 5% by weight and the internal bond strength of the recording sheet is less than 150 g / cm, the surface of the sheet after printing has undulation. And bleeding of the ink worsens. Further, the internal bonding strength of the recording sheet is 500
If it exceeds g / cm, no swelling occurs on the sheet surface after printing, but since the penetration of the ink in the thickness direction is suppressed, the ink diffuses in the surface direction and the ink bleeding worsens. Further, the influence of the pigment content is reduced, and the penetration and diffusion of the ink are slow, so that the background is smeared in the ink jet recording apparatus and the appearance is impaired. For this reason, the upper limit of the internal bond strength is about 455 g / cm.

The pigment content in the support is from 5 to 35 % by weight.
And the internal bonding strength of the recording sheet is 150 to 4
When it is 55 g / cm, an ink jet recording sheet having no undulation on the sheet surface after printing and little ink bleeding can be obtained.

[0025]

EXAMPLES The present invention will be described below with reference to examples of the present invention, but the present invention is not limited to these examples.
Further, "parts" and "%" shown in Examples are parts by weight and% by weight unless otherwise specified. The measurement and evaluation results were performed under the environment specified in JIS P8111 unless otherwise specified.

1) Pigment content in the support The absolute dry weight W ₀ of the support is weighed, the weighed support is put in a crucible, and is burned at a temperature of 550 ° C., and the weight W of the residue in the crucible is weighed. Thereafter, the pigment content P was calculated by the following equation (1).
The unit is [%].

[0027]

## EQU1 ## P = (W / W ₀ ) × 100 [%]

2) Internal bonding strength of ink jet recording sheet Tappi Useful Methods 403
Internal Bond in accordance with the method specified in
It was measured using a Tester (manufactured by Kumagai Riki Kogyo KK). The unit of measurement is indicated as g / cm, but g · cm /
I agree with cm ² .

3) Multi-color bleed rate The multi-color bleed rate is calculated by measuring the diameter of a single color dot of magenta ink (M).
, And the dot diameter of multiple colors of cyan ink and magenta ink (C
M) was determined by the ratio (CM / M). The CM / M value is 1.0 or more, and a value close to 1.0 indicates that the diameter of the single-color dot and the diameter of the super-color dot are equal, and that the sharpness and the chromaticity are good.

4) Swell The swell was visually determined on the sheet surface after printing according to the following criteria. What does not matter in quality is the evaluation of A and B. A: The swell is not recognized, and the appearance is not spoiled. B: The swell is small and does not spoil the aesthetic appearance. C: The undulation is large, and the appearance is impaired.

5) Background Smear After printing a multicolor dot composed of cyan ink, magenta ink and yellow ink, immediately press white paper against the printing surface, and visually check the state of the ink transferred to the white paper based on the following criteria. . The evaluation of A and B indicates that background contamination does not occur in the ink jet recording apparatus. A: Ink transfer is not confirmed, and the background is not stained. B: Transfer of the ink was slightly confirmed, but practically no background staining was observed. C: The transfer of the ink is on the entire surface of the white paper, and the background is stained.

Example 1 A support was made of light calcium carbonate / heavy calcium carbonate / talc with respect to 100 parts of wood pulp composed of 80 parts of LBKP (freeness of 400 mlcsf) and 20 parts of NBKP (freeness of 450 mlcsf). 7 parts of a pigment having a ratio of 10/10/10, 0.10 parts of a commercially available alkyl ketene dimer and 0.05 parts of a commercially available cationic acrylamide having a molecular weight of 5,000,000
After preparing 5 parts, it is made with Fourdrinier paper machine, and the basis weight is 90 g / m ² ,
A support having a pigment content of 5.2% was obtained and flattened using a calender. After providing the ink receiving layer and the back coat layer on the surface of the support, calendering was performed to obtain the ink jet recording sheet of Example 1 having an internal bond strength of 216 g / cm.

The ink receiving layer was composed of 100 parts of synthetic amorphous silica (Fanseal X37B: manufactured by Tokuyama Soda Co., Ltd.), 50 parts of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.), and a cationic dye fixing agent (Sumireze Resin 1001: Sumitomo). 20 parts of a chemical industry) were prepared, and the solid content concentration was 13%.
Coating was performed on the surface of the support with an air knife coater so that the coating amount was 5 g / m ² . Further, a back coat layer was provided on the opposite surface where the ink receiving layer was provided. The back coat layer is kaolin (Hydra Sparse: manufactured by Huber)
100 parts and polyvinyl alcohol (R polymer 113)
0: manufactured by Kuraray Co., Ltd.) and 15 parts of styrene-butadiene-based latex (0617: manufactured by Nippon Synthetic Rubber Co., Ltd.) were prepared to give a coating amount of 5 g / m ² with an air knife coater at a solid content of 35%. Was applied to the opposite side of the ink receiving layer.

Example 2 After a support was obtained under the same conditions as in Example 1, 3 g / m ^{2 of} starch (MS3800: manufactured by Nippon Food Processing Co., Ltd.) was adhered using an inclined size press, and then calendered. Flattening was performed using an apparatus. Thereafter, the same ink receiving layer and back coat layer as those of Example 1 were applied, and calender treatment was performed to obtain an ink jet recording sheet of Example 2 having an internal bond strength of 455 g / cm.

Example 3 A support was made of light calcium carbonate / heavy calcium carbonate / talc with respect to 100 parts of wood pulp comprising 80 parts of LBKP (freeness of 400 mlcsf) and 20 parts of NBKP (freeness of 450 mlcsf). 15 parts of a pigment having a ratio of 10/10/10, 0.10 parts of a commercially available alkyl ketene dimer, and 0.1 part of a commercially available cationic acrylamide having a molecular weight of 5,000,000.
After preparing 05 parts, 1.0 part of commercially available cationized starch and 0.5 part of a sulfuric acid band, papermaking was performed using a fourdrinier paper machine, and the basis weight was 90 g.
/ m ² , a support having a pigment content of 10.2% was obtained and flattened using a calender. After providing the same ink receiving layer and back coat layer as in Example 1 on the surface of the support, calendering was performed to obtain an ink jet recording sheet of Example 3 having an internal bond strength of 280 g / cm.

Example 4 A support was prepared by mixing light calcium carbonate / heavy calcium carbonate / talc with 100 parts of wood pulp comprising 80 parts of LBKP (freeness 350 mlcsf) and 20 parts of NBKP (freeness 400 mlcsf). 60 parts of a pigment having a ratio of 10/10/10, 0.05 parts of a commercially available alkyl ketene dimer, and 0.7 parts of a commercially available cationic acrylamide having a molecular weight of 7,000,000.
After preparing 05 parts, 1.0 part of a commercially available cationized starch and 0.5 part of a sulfuric acid band, the paper was made with a fourdrinier paper machine, and the basis weight was 90 g / m2.
^2. A support having a pigment content of 35.5% was obtained and flattened using a calender. After providing the ink receiving layer and the back coat layer on the surface of the support, calendering was performed to obtain an ink jet recording sheet of Example 4 having an internal bond strength of 152 g / cm.

Example 5 After a support was obtained under the same conditions as in Example 4, 4 g / m ^{2 of} starch (MS3800: manufactured by Nippon Food Processing Co., Ltd.) was applied using an in-line size press, and then calendered. Flattening was performed using an apparatus. Thereafter, the same ink receiving layer and back coat layer as those of Example 1 were applied, and calendering was performed to obtain an ink jet recording sheet of Example 5 having an internal bond strength of 424 g / cm.

COMPARATIVE EXAMPLE 1 The support was 100 parts of wood pulp composed of 80 parts of LBKP (freeness of 400 mlcsf) and 20 parts of NBKP (freeness of 450 mlcsf). Light calcium carbonate / heavy calcium carbonate / talc was used. Of a 30/35/35 pigment, 0.10 part of a commercially available alkyl ketene dimer and 0.02% of a commercially available cationic acrylamide having a molecular weight of 2,000,000.
After preparing 5 parts, it is made with Fourdrinier paper machine, and the basis weight is 90 g / m ² ,
A support having a pigment content of 3.9% was obtained and flattened using a calender. After providing the ink receiving layer and the back coat layer on the surface of the support, calendering was performed to obtain an inkjet recording sheet of Comparative Example 1 having an internal bond strength of 136 g / cm.

Comparative Example 2 After a support was obtained under the same conditions as in Example 1, 5 g / m ^{2 of} starch (MS3800: manufactured by Nippon Food Processing Co., Ltd.) was adhered using an in-line size press, and then calendered. Flattening was performed using an apparatus. Thereafter, the same ink receiving layer and back coat layer as those of Example 1 were applied, and calendering was performed to obtain an ink jet recording sheet of Comparative Example 2 having an internal bond strength of 560 g / cm.

Comparative Example 3 After a support was obtained under the same conditions as in Example 4, 6 g / m ^{2 of} starch (MS3800: manufactured by Nippon Food Processing Co., Ltd.) was applied using an in-line size press, and then calendered. Flattening was performed using an apparatus. Thereafter, the same ink receiving layer and back coat layer as those in Example 1 were applied, and calendering was performed to obtain an inkjet recording sheet of Comparative Example 3 having an internal bond strength of 512 g / cm.

Table 1 shows the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3.

[0042]

[Table 1]

As shown in Table 1, Examples 1 to 5 in which the pigment content in the support according to the present invention is in the specific range of 5 to 35 % by weight and the internal bond strength of the ink jet recording sheet is in the specific range of 150 to 455 g / cm. It can be seen that the undulation and background smear after printing are good, the bleeding rate is low, and the image is excellent in clarity and color. On the other hand, Comparative Examples 1 to 3 which are not in the above specific range have a high bleeding rate, and Comparative Example 1 having a low internal bond strength has poor undulation after printing and has a high internal bond strength. It can be seen that in the cases of Nos. 2 and 3, background fouling also worsens regardless of the pigment content. In particular, it is considered that the increase in the bleeding rate of the supercolor caused in Comparative Examples 2 and 3 was caused by diffusion in the plane direction because penetration in the thickness direction of the support was inhibited.

[0044]

According to the present invention, the ink jet recording sheet is formed by setting the pigment content of the support in the support and the internal bonding strength of the recording sheet to a specific range to form the recording sheet. Subsequent undulation of the sheet surface, bleeding of the ink and background stain can be significantly reduced.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/00 D21H 17/67

Claims (3)

(57) [Claims] 1. In an ink jet recording sheet having at least one ink receiving layer provided on a support comprising wood pulp and a pigment as main components, the pigment content contained in the support is reduced. 5 to 35 % by weight, and the recording sheet has an internal bond strength of 150 to 455 g / cm. 2. An ink receiving layer applied to a support having a coating amount of 1 to 10 g / m ^2.
The ink jet recording sheet according to the above. 3. The pigment content of the support is 5 to 5.
3. The ink jet recording sheet according to claim 1, wherein the content is 30% by weight.